Plastic Surgery

Surgical Site Infections

2009-04-09T04:30:00.003-07:00

Definitions
Overall, surgical site infections (SSIs) are the leading cause of nosocomial infections, accounting for 38% of these complications. By definition, to be an SSI, an infection must occur within 30 days of the operation. SSIs can be broken down into three general categories. Superficial incisional SSIs involve only the skin or subcutaneous tissue of the incision. Signs and symptoms of this type of infection may include pain, swelling, redness, warmth and tenderness. Deep incisional SSIs demonstrate either purulent drainage from deeper tissue, a deep incisional dehiscence, or an abscess in the depth of the incision. Lastly, organ or deep space SSIs involve infections in manipulated regions other than the skin and subcutaneous tissue that was opened during the procedure. By definition, these infections must contain purulent drainage, positive cultures with fluid aspiration or documentation of the presence of an abscess. If a foreign body such as mesh or titanium was left in the wound an SSI can occur up to one year postoperatively.

Risk Factors
Generally speaking, the overall well being and the severity of any comorbid conditions determine how susceptible a patient is to wound infections. The American Society of Anesthesiology rates patients’ operative risk according to their level of illness and comorbidities, termed the ASA class. There is a close correlation between the severity of the preoperative risk and the risk of wound infection. Furthermore, greater operative time is also associated with an increased risk of developing an SSI. When planning an operation, the surgeon must consider the level of expected contamination. Clean surgical procedures are those that involve only skin and the musculoskeletal soft tissue and carry approximately a 2% chance of developing an SSI (although it must be noted that wound infection rates are probably underreported). Clean-contaminated procedures are those that involve the planned opening of a hollow viscus (e.g., the respiratory, biliary or gastrointestinal tracts) and have a 7-15% risk of becoming infected. Contaminated procedures are those that introduce nonsterile, bacteria-rich contents into the wound for a short period of time (e.g., penetrating abdominal trauma, unplanned enterotomies) and lead to SSIs in 20% of cases. Dirty procedures take place in an infected setting (e.g., bowel resection for an abscess related to Crohn’s disease, removal of infected prosthesis). Approximately 20-40% of these wounds will become infected if closed primarily.

Bacteria and Prophylaxis
Whereas most SSI are caused by skin derived Gram-positive cocci, including Staphylococcus aureus, coagulase-negative staphylococci such as Staphylococcus epidermidis and Enterococcus species, site-specific pathogens, may infect wounds. Consideration for Gram-negative bacilli should be given to any wound that is located near the site of bowel injury or repair, and when either bowel or tracheopharyngeal structures are violated, both enteric aerobic bacteria such as Escherichia coli and anaerobic bacteria such as Bacteroides fragilis may be of concern. Prophylaxis for clean surgery is controversial. It is generally accepted that when bone is violated (e.g., during cranial vault reconstruction) or when a prosthesis is inserted, preoperative antibiotics are indicated. Less convincing data exists for straightforward soft tissue surgery (e.g., scar revisions).

Patient factors
Anemia (postoperative)
Ascites
Chronic inflammation
Corticosteroid therapy (controversial)
Obesity
Diabetes
Extremes of age
History of irradiation
Hypocholesterolemia
Hypoxemia
Malnutrition
Peripheral vascular disease
Recent operation
Remote infection
Skin carriage of staphylococci
Skin disease in the area of infection (e.g., psoriasis)

Environmental factors
Contaminated medications
Inadequate disinfection/sterilization
Inadequate skin antisepsis
Inadequate tissue oxygenation

Treatment factor
Drains
Emergency procedure
Hypothermia
Inadequate antibiotic prophylaxis
Prolonged preoperative hospitalization
Prolonged operative time When choosing an antibiotic agent, the following factors should be considered:

It should have minimal side-effects and be safe for the patient.
It should have a narrow spectrum of coverage for the expected organisms.
It should not be overused (making it less likely that bacteria have developed resistance).
It should cover typical infections that are specific for the institution.
It can be used for a brief period of time (less than 24 hours).

Long prophylactic courses have been associated with an increased risk of nosocomial infections and multi-drug resistance. For clean and most clean-contaminated cases, a first-generation cephalosporin should be used. If a patient has a documented penicillin allergy, clindamycin is an alternative. Only in the setting of a hospitalized patient in an institution that carries a high rate of methicillin-resistant S. aureus (MRSA), should vancomycin be considered for prophylaxis. It is important to recall that the timing of the antibiotic dose determines its effectiveness. Preoperative prophylaxis should be closed within two hours of incision time. Given too early, the antibiotic can be cleared before the case is started. Some benefit can be gained from intraoperative dosing if antibiotics are not given before the case begins, but no benefit has been shown when the first dose is given after the case ends. This loss of benefit after skin closure is related to the fact that sutured wounds exist in a low blood flow state owing to vasoconstriction, the use of electrocauterization for hemostasis, and the constrictive effects of the suture closure. Therefore, antibiotics will not reach the surgical site. In extremely lengthy cases, redosing intraoperatively is recommended.

Prevention and Treatment
In the weeks to months before a planned operation, much can be done to maximize the immune state and wound healing capabilities of the patient. Smokers should be encouraged to stop at least one month prior to their surgery. Smoking is a known vasoconstrictor that can reduce oxygen delivery to wounded tissue, and its effects have been found to last weeks beyond the point of smoking cessation. The nutritional status of the patient should be taken into consideration as well. Obese patients should be encouraged to lose as much weight as possible while maintaining a healthy, protein-rich diet, and in the malnourished hospitalized patient, even a short 5-7 day course of parenteral or enteral nutrition has been shown to significantly reduce the risk of SSIs. Studies show that having a patient take a preoperative shower with an antiseptic soap (e.g., hexachlorophene) can reduce skin bacterial load. However, shaving the planned surgical site with a razor either the night before surgery or immediately preoperatively should be discouraged due to the transient bacterial infestation that it promotes. Studies report greater than a 3-fold increase in infection rates with shaving versus hair clipping (5.6 vs. 1.7%). Finally, known S. aureus carriers should have their nasal orifices treated with topical 2% mupirocin. Intraoperatively, care should be taken to keep the patient warm and well hydrated. This will improve blood flow to the wound and maximize oxygen delivery. Even 30 minutes of preoperative warming can reduce patient risk for SSI by two-thirds in some cases. Adequate oxygenation is important for cellular function and bacterial destruction via superoxide and peroxide formation. Case length should be kept to a minimum, given the fact that infection rates almost double for each hour an operation lasts. Tissues should be handled gently and electrocautery for hemostasis should be kept to a minimum. During the case, wounds should be kept moist and retractors should be released periodically to restore blood flow. The smallest possible suture diameter should be used to minimize foreign material in the wound (studies show that on average, surgeons use sutures one size larger than needed), and the prudent use of drains should be encouraged. By acting as a conduit for bacterial invasion and preventing epithelial closure of wounds, drains probably cause more SSIs than they prevent and they should be removed as soon as possible. Antibiotic prophylaxis of an indwelling drain is never indicated. High pressure pulse irrigation and topical antiseptic washes have been proven to be of some benefit in the contaminated or dirty wound. Both during the case and postoperatively, blood glucose concentration should be kept under tight control (80-110 mg/dl). And finally, postoperative nutrition should be optimized. Controversy exists on whether it is appropriate to close contaminated wounds primarily. Studies in adults show that this practice can lead to a higher rate of wound failure and a greater cost of care. It is recommended that a delayed primary closure of the incision be used. This involves either placing untied sutures during the case that can later be cinched down, or using adhesive strips for closure when the wound is ready. Until the time when the wound appears to have minimal debris and no apparent progressing erythema, wet-to-dry, twice daily packing should be used (usually for 4-5 days).

Pearls and Pitfalls
Antibiotic prophylaxis of clean surgical procedures (e.g., elective operations on skin and soft tissue) is controversial based on a single randomized trial that showed benefit in breast and groin hernia surgery. The controversy persists because the incidence of superficial surgical site infection was so high (4%, versus an expected incidence of about 1%) in the placebo group. Evidence that antibiotic prophylaxis is indicated for soft tissue procedures of other types is lacking entirely, and prophylaxis cannot be recommended. If administered, antibiotic prophylaxis should be given before the skin incision is made, and only as a single dose. Additional doses are not beneficial because surgical hemostasis renders wound edges ischemic by definition until neovascularization occurs, and antibiotics cannot reach the edges of the incision for at least the first 24 hours. Not only is there lack of benefit, prolonged antibiotic prophylaxis actually increases the risk of postoperative infection. Increasingly in the practice of plastic surgery, there is a tendency to leave closed-suction drains in place for prolonged periods in the erroneous belief that the incidence of wound complications is reduced by prolonged drainage. Nothing could be further from the truth. Data indicate that the presence of a drain for more than 24 hours increases the risk of postoperative surgical site infection with MRSA. Closed suction drains must be removed as soon as possible, ideally within 24 hours. Prolonged antibiotic prophylaxis is often administered to “cover” a drain left in place for a prolonged period. This is a prime example of error compounding error, and is a practice that must be abandoned.

Chronic Wounds

2009-03-06T06:11:00.002-08:00

Normal Skin Flora
The skin is covered with microorganisms. These can be either resident organisms, those that can typically be found on the subject’s skin, or transients that are often seen on the skin surface but are quickly shed during normal body hygiene or by skin sloughing. While these organisms are usually bacteria, the yeast Pityrosporum and skin mite Demodex are also commonly found. These colonizing microbes take residence in the crypts and crevices that favor bacterial growth, and prevent pathologic species from gaining access to these areas. Human beings are protected from bacterial overgrowth and invasion at the surface by a number of defense mechanisms. A layer of dead, keratinous epithelial cells known as the stratum corneum is the outermost layer of skin. As the keratin sloughs, it removes attached organisms with it. Sebaceous glands secrete an oily, lipid-rich, acidic substance, (pH range of 4.2 to 5.6) that acts to retard bacterial growth. Bacteria become more active on the skin surface as the pH rises above 6.5, as is seen with the use of many cleansing and moisturizing agents. Should foreign organisms get past these defenses, the antigen-presenting Langerhans cells found in the epidermis and the phagocytosing macrophages and immune-stimulating mast cells present in the dermis rapidly mobilize the body’s cellular and humoral immune responses.

Contamination vs. Infection
Cutaneous wounds, by definition, have lost their protective barrier and are subject to invasion by not only foreign bacteria introduced through the environment,

Bacteria
Staphylococcus Micrococcus Peptococcus Corynebacterium Brevibacterium Propionibacterium Streptococcus Neisseria Acinetobacter but also the local bacterial flora that is present on intact skin.

These wounds occur in the setting of various pathologies and are usually chronic in nature before being brought to the attention of a plastic surgeon. Unlike most surgical incisions, these wounds heal by secondary intention and are always colonized by bacteria. They require extensive granulation tissue formation and keratinocyte migration for closure, involving endothelial cells and fibroblasts for the purposes of neovascularization and matrix production, respectively. For this to occur, macrophages and a varying milieu of growth factors must be present. Along with neutrophils, macrophages also act to disinfect the wound, killing foreign organisms by the generation of peroxide and superoxide radicals. The clinical spectrum of bacterial invasion exists on a continuum from least to most severe: contamination, colonization, local infection or critical contamination, invasive infection and sepsis.

Contaminated wounds have nonreplicating organisms within their borders. These wounds will go on to heal normally.
Colonized wounds have replicating bacteria, but these bacteria are nondestructive and contained within the wound. A hallmark of colonization is that it does not delay the wound healing process.
Local infection or critical contamination is an intermediate level of bacterial invasion characterized by granulation tissue that has an unhealthy appearance, and wound healing that may be delayed. In this type of wound, however, tissue invasion is not present. This stage is notable for the absence of other signs of infection such as cellulitis or pus formation.
Invasive infection occurs once bacteria have invaded through the wound bed, tissue destruction has begun, and an aggressive immune response is present. Signs and symptoms of invasive infection include pain, edema, erythema and fever. The finding of a chronic, nonhealing wound, often with pus formation and tissue necrosis is often evident.
Sepsis occurs when the infection spread systemically, and cardiovascular instability and organ-system dysfunction develop.

The Molecular Biology of Bacterial
Infection Low levels of bacteria in wounds actually help to promote wound healing by stimulating brisk monocyte and macrophage activity. However, as their number or virulence increases, the tissue response to their presence disrupts and prolongs the inflammatory phase of wound healing, depletes the components of the complement cascade, interferes with normal clotting mechanisms, and alters leukocyte function. The level of pro-inflammatory cytokines, including interleukin-1 and tumor necrosis factor-alpha, rises and stays elevated. Elevated levels of matrix metalloproteinases and a lack of their inhibitors lead to tissue breakdown and growth factor inhibition. Bacteria also compete with local cells for oxygen, reducing its availability to these cells and stimulating an angiogenic response, leading to friable granulation tissue that is prone to bleeding.

Bacteria in Wounds
Classic teaching is that wounds with greater than 105 organisms/gram should be considered infected whereas those with a lower bacterial count should not. Although studies do show that wounds with bacterial counts higher than this heal more slowly and have a higher rate of infection, a more practical approach to diagnosing the infected wound is encouraged. As wounds mature, not only do the species of organisms present in the wound change, the wounds begin to carry a higher level of bioburden, meaning a higher baseline number of colonies without being infected. Conversely, the more virulent bacteria, such as beta-hemolytic streptococcus and some rare Clostridium species, can easily cause infection at lower quantitative levels than the more commonly occurring species. Finally, the status of the patient’s immune response has a role in the patient’s likelihood of developing an infected wound. Therefore, the surgeon is encouraged to study the appearance of the wound and the overall clinical picture when deciding whether a wound is infected. Although it is important to note the classic signs and symptoms of infection including erythema, edema, fever and an elevated white blood cell count, recent studies attempting to establish evidence-based criteria for the determination of a chronic wound infection have shown that increasing pain, friable granulation tissue, foul odor and wound breakdown are the most sensitive indicators. Bacteria in chronic wounds often establish a biofilm. This is an extracellular, polysaccharide-rich matrix in which the organisms are embedded. Within this glycocalyx is a system of channels, like a primordial circulatory system, that allows the bacteria to remain viable with less direct dependence on the host tissue. Cells in this environment become more sessile and less metabolically active. As a result, they are resistant to host immune responses and antibiotic therapy. Biofilms often coat foreign and implanted material, making infections in this setting more difficult to treat, and certain bacteria such as Pseudomonas aeruginosa have a predilection to biofilm production.

Bacteria Occurrence (%)
Staphylococcus aureus 20 Coagulase-negative staphylococci 14 Enterococci 12 Escherichia coli 8 Pseudomonas auruginosa 8 Enterobacter species 7 Proteus mirabilis 3 Klebsiella pneumonia 3 Other streptococci 3 Candida albicans 3 Group D streptococci 2

Clinical Evaluation
A thorough history includes information related to the chronicity of the wound, any changes to the wound appearance, and details that should make the clinician suspicious of a more invasive bacterial involvement (e.g., pain, fever). Mitigating factors such as comorbid conditions that could lead to immunosuppression, the use of any immunosuppressive medications, previous radiation in the wound area and the overall functional status of the patient are important to explore. In addition to a white blood cell count and blood cultures, laboratory tests can include the erythrocyte sedimentation rate and C-reactive protein. Although not specific, in a patient with no recent history of surgery or acute illness, their value is in helping to determine the level of systemic response to a wound and in helping to determine the presence of a deep wound infection. When examining a wound, its depth and width should be measured and a careful inspection and probing should be done. Attention to findings such as erythema at least 5 mm beyond the wound edges, expressed pus, necrotic debris or granulation tissue that is dark, friable or heaped above the wound edges can help to determine the extent of infection. Foreign bodies such as old strands of gauze should be removed and the presence of underlying foreign material such as sutures or mesh should be ruled out. Care must be taken to ensure that wounds overlying osseous structures do not have any exposed bone at their base that would suggest the presence of osteomyelitis. As stated earlier, bacterial cultures can help to make a diagnosis and guide appropriate therapy. In a wound that has been appropriately cleaned and prepared, a swab of the deeper tissue can give a qualitative notion of which bacteria are present. It does not, however, allow the clinician to quantitate the amount of bacteria within the wound. For this, the gold standard is a biopsy culture. A punch biopsy is taken and ground into a liquid state from which serial dilutions are cultured. A measure of colonies per milligram can then be reported.

Treatment
Antibiotics are ineffective in penetrating chronic, nonhealing wounds. Debridement is the best option for clearing bacterial loads and removing nonviable tissue. If not performed, necrotic material can release endotoxins that inhibit keratinocyte migration and matrix production, and can prolong the inflammatory response, promoting matrix-destroying proteases. Methods of debridement include sharp, mechanical, chemical and biodebridement. Sharp, or surgical debridement affords the luxury of speed, since it can be performed at the bedside with nothing more than scissors and a pair of forceps. More extensive debridement may require anesthesia, and should be performed in the operating room. Mechanical debridement is the eradication of dead tissue by the sequential changes of dressings that are inserted moist into the wound and removed after they are allowed to dry. Exudative and necrotic tissues adhere to the drying gauze and are pulled out of the wound with the gauze. This technique has only a limited ability to remove structurally intact or strongly adherent devitalized tissue. The classic “wet-to-dry” dressing is a mechanically debriding dressing. Chemical debriding agents are enzymatic compounds that break down tissue. They are most effective in moderately sized areas of necrosis or in those patients that will not tolerate an operation. In order to gain maximum benefit, larger eschars should be cross-hatched or excised to allow for better penetration of the agent. The papain-containing cream, Accuzyme®, is commonly used for this purpose. Biodebridement involves the application of sterile maggots into a wound for periods of 48-72 hours. The maggots feed on, and thus remove dead tissue before being irrigated out. This process can be repeated as necessary. Needless to say, it is not a commonly used technique. Antibiotics do have a role in the treatment of chronic, infected wounds once debridement has achieved healthy wound borders. Empiric antibiotics should be selected based on the bacteria that are likely to be involved. For example, empiric antibiotics for wounds near the oropharynx and diabetic foot wounds should include coverage for anaerobic species. The Gram stain can give a general idea of whether Gram-positive, Gram-negative or a combination of bacteria is present. Once culture results return over the subsequent 2-3 days, antibiotic coverage should be tailored to the involved organisms. Topical antibiotic preparations can help to reduce bacterial load and can be used with some success in an adjuvant setting in the select wound population. Prudence should be taken with their use, however, because many of these preparations also impair the function of the superficial cells necessary for wound healing. They should never be used in wounds related to venous disease, as these wounds are more prone to sensitivity reactions. Examples include: iodine or iodophor paint, sodium hypochlorite solution, hydrogen peroxide, acetic acid, antibiotic creams or the newer cadhexomer iodine and nanocrystalline silver. For wounds that arise in the setting of underlying pathology, treating the disease process can increase the speed and likelihood of wound healing. For venous stasis ulcers, reducing edema fluid with Unna boot compression, elevation and diuresis can improve oxygen delivery and thus cellular function. Patients with diabetic foot ulcers should have their blood sugar strictly controlled given the deleterious effects of hyperglycemia on neutrophil and monocyte function. If ischemia is believed to be contributing to the etiology or chronicity of a wound, smoking cessation and elimination of dehydration and anemia should all be considered in the treatment plan. Ultimately arterial revascularization with or without surgical reconstruction using local or microvascular flaps may be necessary.

Hidradenitis Suppurativa
This condition is due to infection of the apocrine sweat glands, most commonly in the axillary, perineal and groin regions. It results in recurrent, draining abscesses and sinus tracts that can lead to severe pain and debilitation. Lesions in the axilla that heal may scar and secondarily cause contracture limiting arm motion. Active infection should be treated with a 1-2 week course of oral antibiotics and is usually due to Gam positive cocci. Cultures should always be taken since other bacterial infections can occur, and the antibiotic should be appropriately selected. Surgical treatment consists of full-thickness excision of the infected dermis and any involved subcutaneous fat. Primary closure can be obtained in small- to moderate-sized wounds without active infection. Larger defects, or those that are grossly infected, should not be closed primarily. They should be allowed to granulate with dressing changes, followed by split-thickness skin grafting or healing by secondary intention. Incomplete excision of the involved tissue is common due to retained sinus tracts or deep infected glands. When this occurs, there is a high likelihood of recurrence and skin graft failure.

Tissue Expansion

2009-03-05T01:02:00.002-08:00

Introduction

Tissue expansion relies on the ability of skin and soft tissues to generate in response to tension. In plastic surgery, tension is generated by implanting a subcutaneous balloon (expander) that is inflated over a period of weeks; new tissue is generated in response to the constant stretch caused by the progressive inflation of this expander. This tissue can be used to reconstruct extirpative or traumatic defects such as those encountered after mastectomy, burn excision, or removal of giant nevi.

Biological Basis of Tissue Expansion

A number of studies support the concept that the increase in skin surface area after expansion is due to the generation of new tissue rather than the stretching of existing skin. In culture, mechanical stress induces fibroblast and epidermal hyperplasia. These cells preserve their phenotype without malignant degeneration. This observation is supported by the fact that there has never been a reported case of skin malignancy secondary to tissue expansion.

From a histological standpoint, adult and pediatric skin responds to expansion in the same manner. Within 1 week of expansion, the epidermis begins to thicken and the dermis thins. The skin appendages do not change. The subcutaneous fat and muscle atrophy. Cellular proliferation reduces the resting tension of the skin over time, enabling another round of expansion to take place. Once the process is complete, the expanded skin eventually returns to its baseline thickness. The vessels of the skin and subcutaneous tissue also resume their pre-expanded size and number; however anecdotally, some flaps demonstrate increased vascularity.

Indications

In general terms, expansion of tissue is used to improve rotation, transposition or advancement of local or regional flaps, or to increase the harvest of full-thickness skin grafts. Recently, tissue expansion has been successfully applied to myocutaneous and free flaps. In adults, aside from their use in breast reconstruction, tissue expanders are used primarily for secondary burn and trauma reconstruction in the head and neck region. In the pediatric population, expanders have been used in a multitude of reconstructive procedures. The most common indication in children is to reconstruct defects left by excision of giant congenital nevi. Tissue expansion is contraindicated in infected skin. Although expansion is possible in radiated or scarred tissue, it is associated with a much higher complication rate and should be avoided whenever possible.

Technique

Expanders come in a variety of shapes and sizes, and there is no absolute ideal expander for a given site or condition. Expanders can have either internal or external filling ports. Most experienced surgeons recommend using remote ports. These should be placed away from the expander. Internal ports have both a higher failure rate and a greater incidence of accidental expander rupture. In children, the use of internal ports is associated with a higher rate of exposure of the expander due to the pressure exerted on the skin by the port. Whenever possible, the incision should be placed within tissue destined to be excised, as in the case of congenital nevi. Straight incisions along the border of the defect should be avoided because this will enlarge the defect and may interfere with flap coverage. An alternative is to use a U- or V-shaped incision that is hidden and remote from the defect. Such incisions should be perpendicular to the direction of expansion in order to maximize skin blood supply. When doing serial expansion, longitudinal blood supply must be preserved. This holds true especially in the trunk and extremities.

The expander should be placed on top of the deep fascia (or subgaleal in the scalp), unless the plan is to incorporate muscle into the expanded flap. The pocket should always be larger than the base diameter of the expander. Blunt dissection in a single fascial plane is safest for preserving blood supply. Most surgeons overinflate tissue expanders beyond the manufacturer’s recommended maximum capacity. Studies have demonstrated that significant overinflation is possible before weakening or rupturing. The rate of inflation is variable and largely based on surgeon preference. Patient comfort and signs of tissue perfusion, such as tension, color, and capillary refill, guide the filling rate. Filling is usually initiated one week after surgery.

Tissue expansion should continue until the expanded area is larger than the defect, because of the length that is lost upon advancement and inset of the flap. The use of rotation and transposition flaps enables the transfer of tension from the tip of the flap more proximally to its base. A single or double back-cut can be performed prior to inset in order to gain extra length. Lastly, the donor site should be closed in layers after the implant capsule is excised. Pre-expansion of distant pedicle- or free-flaps facilitates closure of otherwise tight donor sites.

Intraoperative Expansion

Most surgeons fill the expanders intraoperatively with sufficient saline to eliminate dead space and tamponade raw surfaces to help prevent postoperative bleeding. There is, however, an alternative to traditional prolonged expansion. Immediate intraoperative expansion combined with broad undermining of the defect can help reduce the tension that occurs on the distal parts of a local flap. In rapid expansion, the skin initially expands due to its elasticity and the displacement of interstitial fluid. Within minutes, the alignment of the collagen fibers changes due to the stretch. This process yields up to 20% more tissue for flap coverage. Intraoperative expansion is indicated for relatively small defects, such as in coverage of defects of the ear.

Scalp

Although tissue expansion does not increase the number of hair follicles, the size of the hair-bearing region can be doubled without a noticeable decrease in hair density. As such, tissue expansion may be used a means of treating male pattern baldness in addition to reconstructing the scalp. Expanders are most commonly placed in the occipital or posterior parietal regions. They should be placed under the galea, superficial to the periosteum. It usually requires 6-8 weeks to complete the expansion in adults, and up to 12 weeks in children. Radial scoring of the galea at the time of surgery can speed the process. Once the expansion is complete, flaps are advanced or transposed, ideally based on named arteries of the scalp. It is important to orient flaps so that the correct direction of hair growth is maintained. Although galeal scoring or capuslotomy incisions can be useful, wide undermining is a safer method of recruiting tissue.

Forehead

The brow position is the most important structure to preserve during forehead expansion. When possible, two or more expanders are used with incisions hidden within the hairline. For mid-forehead lesions, bilateral, temporal expanders are used, and the skin is advanced medially based on the superficial temporal arteries. Expanders should be placed deep to the frontalis muscle. Expansion can usually begin 7-10 days postoperatively. When a large forehead flap is required for nasal reconstruction, the forehead skin can be pre-expanded prior to flap transfer.

Face and Neck

The skin of the neck and face is relatively thin. Therefore, multiple expanders with smaller volumes are preferable to a single large expander. In general, however, a single larger expander is preferable to several smaller expanders. Careful planning is essential in determining where to place the expanders, and where incisions should be located. Considerations such as preserving aesthetic units, matching skin color, avoiding distortion of the eyelids and oral commissure, and facial symmetry are all essential. The expander is usually placed above the platysma muscle in order to avoid risk of facial nerve injury and to keep the flap from being excessively bulky. The expanded flaps can be advanced, rotated, or transposed. Incisions should be placed in skin creases such as the nasolabial fold. Expanding the hairless skin adjacent to the mastoid region can increase the available tissue for reconstructive procedures of the ear. The skin above the clavicle can be expanded to provide full-thickness skin grafts to the face.

Trunk

Unlike the head and neck, there are very few critical landmarks on the trunk that must be preserved. Aside from the breast and nipple-areola complex, distortion of the skin and soft tissues of the trunk is well-tolerated. For defects requiring excision, multiple expanders surrounding the defect are often employed. Many myocutaneous flaps of the trunk, such as the latissimus dorsi, TRAM and pectoralis flaps, can be pre-expanded in order to increase their size and facilitate donor site closure. Expanders can also be used to expand the skin of the abdomen for use as a donor site of full-thickness skin grafts.

Extremities

Tissue expansion in the extremities has been reported to have a higher complication rate in comparison to other regions and therefore should not be a first choice among the reconstructive options. The blood supply and drainage of the extremities is inferior to that of the trunk and head. This predisposes limbs, especially below the knee, to an increased rate of infection and wound complications. Multiple expanders are usually required in the extremites.

Complications

Proper placement and filling of tissue expanders has a steep learning curve. With experience, the complication rate drops dramatically. Among all patients, the major complication rate is about 10% and includes implant exposure, deflation, and wound dehiscence. Minor complications also occur in about 10% of patients. These include filling port problems, seroma, hematoma, infection and delayed healing.

Patients under the age of 7 have the highest risk of complications. One explanation for this is that young children are more prone to expander rupture due to external pressure on the expanded skin. Expansion in the extremities caries twice the risk of complication compared to other regions. The use of tissue expansion in burn reconstruction and soft tissue loss has a 15-20% major complication rate, whereas for congenital nevi it is 5-7%. Finally, tissue that has undergone serial expansion (two or more prior expansions) is at a higher risk for a major complication.

Pearls and Pitfalls

Tissue expansion should be avoided in infected fields, in close proximity to a malignancy, in skin-grafted regions, and in skin that has been previously radiated.

Every effort should be made to place the incision as far as possible from the region to be expanded, unless the incision can be incorporated into the tissue that is destined to be excised. If the incision is subject to the tension of expansion, it becomes at risk for dehiscence and hypertrophic scarring.

A key point in tissue expansion is the development of an adequately sized pocket. If the pocket is too small, expansion will likely fail. If the pocket is overly large, the expander can shift positions, resulting in expansion of the wrong tissue. Textured expanders are less likely to shift after placement.

The rate of expansion is variable and depends both on the body site as well as patient factors. Some skin is more amenable to expansion, and some patients can tolerate the discomfort better than others. It is possible to be overly aggressive with the rate of expansion, resulting in overlying skin ischemia, necrosis and ultimately implant extrusion.

As a general rule, the diameter of the expanded flap should be 2-3 times the diameter of the skin that is to be excised

Alloplastic Materials

2009-02-21T23:42:00.004-08:00

Introduction

Advances in medical technology have allowed plastic surgeons to utilize synthetic materials as an alternative to autologous tissues when performing many of today’s aesthetic and reconstructive surgeries. Although autologous materials are generally preferred, synthetic materials provide several advantages over tissues obtained from the patient:

Not resorbed over time (unless they are designed to do so)
Do not require a second surgical donor site
Provide more material than can often be obtained from the patient
Can be custom-tailored to the individual patient
Reduce operating time since graft harvesting is not performed

Because of the many benefits to using alloplastic materials, there is currently a strong interest in developing the ideal implant material which would possess the following characteristics: it should (1) be chemically inert; (2) be incapable of producing hypersensitivity or a foreign body reaction; (3) be easily contoured; (4) retain stable shape over time (except when desired); (5) be noncarcinogenic; (6) become ingrown or replaced by living tissue; (7) be easy to remove and sterilize; and (8) not interfere with radiographic imaging. Despite much effort and ingenuity, creation of the ideal implant material has yet to be accomplished. However, various alloplastic materials are being used today in plastic and reconstructive procedures, and many of them have proven quite promising.

Pre- and Intraoperative Considerations
The vascularity of the recipient site and the ability to provide sufficient soft tissue coverage of the implant must be assessed preoperatively. Decreased vascularity secondary to scar tissue (from previous surgeries) or radiation impairs the establishment of normal fibrovascular tissue encapsulation and may interfere with the normal inflammatory response if the implant were to become infected.

In order to prevent implant exposure or extrusion, soft tissue coverage over an implant should be as thick as possible. The size of the implant should be comparable to that of the tissue pocket or wound cavity in order to avoid tension of the overlying soft tissue, and the implant should be fixated to a stable adjacent structure to prevent migration of the implant. All patients should receive perioperative intravenous antibiotics followed by a postoperative oral course, although the optimal antibiotic choice and duration have yet to be determined for most implants. What is clear is that intraoperative handling of the implant should be minimized in order to prevent bacterial transmission, and strict adherence to sterile technique is essential.

Classification of synthetic materials used in plastic and reconstructive surgery

Silicone-based materials:

BioPlastique

Injectable silicone

Silastic sheets

Silicone

Silicone gel

Polytetrafluoroethylene:

Gore-Tex

Proplast I and II

Teflon

High density polyethylene:

Medpor

Polymer mesh:

Dacron (Mersilene)

Dexon

Prolene

Supramid Vicryl

Biological glasses:

Bioactive glasses (Bioglass)

Glass ionomer

Tissue adhesives:

Cyanoacrylate

Acrylics:

HTR Polymer

Methylmethacrylate

Choice of Alloplastic Material
The type of procedure as well as the size and character of the defect being augmented often dictate the type of implant material. In the preantibiotic era, inert materials such as gold, silver, platinum and paraffin were used with little success and were quickly abandoned. Currently, there are numerous implantable materials being used today (Table 14.1). These materials are used in a wide range of procedures, such as aesthetic procedures, craniofacial surgery, maxillofacial trauma, breast reconstruction and hand surgery. Table 14.2 lists the common uses for the various allopastic implants.

Silicone
Silicone-based prosthetics have been used as medical implants since the 1950s due to their chemically inert nature, resistance to degradation, and lack of significant allergic reactions. Silicone is useful for a variety of aesthetic surgeries, complex contouring and reconstructive procedures. Silicone comes in the form of silicone gels, silicone rubber or solid silicone implants. Silicone gels can provide a more natural feel, as seen with breast implants, but the risk of rupture requiring capsulectomy is a distinct disadvantage. The use of silicone gel has been surrounded by controversy related to concerns about migration, toxicity and an unproven association with systemic disease, leading to restriction of the use of silicone gel implants by the FDA in 1992. This ban was recently lifted after an extensive unbiased review by the Institutes of Medicine. Silicone rubber is used for tissue expanders, the outer shell of both saline-filled and silicone gel-filled breast implants, and as an onlay material for the augmentation of the bony skeleton and soft tissues. However, silicone rubbers are relatively weak and tend to tear, leading to implant failure. Solid silicone implants are commonly used for chin and malar augmentation, and have been used in nasal, chest and calf augmentation, as well as in joint replacement and tendon reconstruction.

A list of the procedures that commonly employ allopastic materials

Procedures

Materials Used

Cranioplasty and forehead augmentation

Glass ionomer and bioactive glass Hard-Tissue-Replacement (HTR) polymer

Methylmethacrylate

Medpor

Poly(L-lactide) and polyglycolic acid plates and screws Silicone

Anterior mandibular augmentation

Medpor Polyamide

mesh

Silicone

Mandibular body and angle augmentation

Glass ionomer and bioactive glass

Medpor

Methylmethacrylate

Poly(L-lactide) and polyglycolic acid plates and screws

Malar and maxillary reconstruction

Glass ionomers

Gore-Tex

Medpor

Methylmethacrylate

Polyamide mesh

Silicone

Teflon

Zygomatic reconstruction

Glass ionomers

Medpor

Gore-Tex

Poly(L-lactide) and polyglycolic acid plates and screws

Silicone

Orbital reconstruction

Gore-Tex

HTR Polymer

Medpor

Poly(L-lactide) Silicone

Teflon

Ear reconstruction

Medpor

Silicone

Tendon repair

Gore-Tex

Cyanoacrylate

Soft tissue augmentation

BioPlastique

Gore-Tex

Breast augmentation and tissue expansion

Silicone (saline or silicone gel filled)

Wound repair and scar revision

Cyanoacrylate

Silastic sheets

Chest and abdominal wall reconstructions

Dacron mesh

Gore-Tex

Prolene mesh

Vicryl mesh

Nasal augmentation

Gore-Tex

Polyamide mesh

Silicone

Because silicone is not porous, tissue ingrowth does not occur. A fibrous capsule forms around the implant that is relatively avascular and can contract which may lead to implant migration. This avascular capsule is a potential space for infection and in the setting of infection may require removal of the implant.

BioPlastique
BioPlastique® is a nonbiodegradable, relatively inert injectable liquid used for soft tissue augmentation. The textured surface of the particles allows for tissue ingrowth, and the particle size is large enough to prevent engulfment by macrophages but small enough to become encapsulated within 3 to 6 weeks. Studies on the use of BioPlastique demonstrate good-to-excellent results in augmenting small defects on the dorsal nose, malar area, cheeks and chin with no adverse immunologic reactions. Although the clinical results with Bioplastique have been encouraging, it is not FDA approved at this time.

Polymethylmethacrylate
Polymethylmethacrylate (PMMA) is an acrylic polymer used as a bone substitute in plastic surgery and neurosurgery. PMMA is radiolucent, extremely durable and completely biocompatible, making it a widely used material for cranial bone reconstruction-alone or in combination with wire or mesh reinforcement. When powdered granules of methylmethacrylate polymer are mixed with methylmethacrylate liquid monomer, a moldable dough forms as the monomer polymerizes and hardens in about ten minutes. Near the end of the polymerization process, an exothermic reaction occurs that can potentially damage the local tissues, the major complication associated with the use of PMMA. This can be avoided by continually irrigating the implant bed with cool saline during the polymerization. A rare, but serious complication is the inadvertent entry of the PMMA into the venous or arterial systems. If this occurs it can cause complete heart block, cardiac arrest and other arrhythmias. This complication is most often seen during orthopedic procedures where PMMA is used for joint replacements or fracture repair. Hard-tissue-replacement (HTR) polymer is a porous form of PMMA that allows for fibrous ingrowth, leading to an implant that is nonresorbable and very stable. Applications for HTR include chin and malar augmentation, with potential for additional uses in craniofacial reconstruction.

Polyester (Dacron®, Mersilene®)
Polyethylene terephthalate (Dacron) is a biocompatible, flexible, nonabsorbable polymer that is used as a suture material, as a prosthetic material for arterial replacement, and as a mesh (Mersilene) in abdominal and chest wall reconstruction. Its use has also been described for chin and nasal augmentation. Biodegradable Polyester (Polyglycolic Acid, Poly-L-lactic Acid) Polyglycolic acid (PGA) and Poly(L-lactide) (PLLA) are polymers that are degraded in the body at physiologic pH over the course of weeks to months. These resorbable polymers are available as mesh sheets for body wall reconstruction and as rods for the internal fixation of fractures and osteotomies. They have also been fashioned into resorbable miniplates and screws for the fixation of bones of the craniofacial skeleton. Although they do not appear to have any cytotoxic effects, they do provoke an inflammatory or foreign body response after implantation.

Polyamide Mesh (Supramid®, Nylamid®)
Polyamide mesh is a woven, polymer mesh implant that is biocompatible, can be easily shaped and sutured, allows for fibrous tissue ingrowth, and has been used for the repair of orbital floor defects. It seems to be well tolerated and has a low rate of extrusion, even in areas of thin skin such as the nasal dorsum. However, polyamides do undergo resorption and induce an inflammatory response, making their use in facial augmentation and reconstruction somewhat limited.

Porous Polyethylene (Medpor®)
Medpor is a high-density, porous polyethylene implant used frequently in facial surgery because it is nonantigenic, nonallergenic, nonresorbable, highly stable and easy to fixate. In addition, Medpor is available in a wide variety of preformed shapes for its use as a malar, chin, nasal, orbital rim, orbital floor and cranial implant, as well as an auricular framework in postburn ear reconstruction. Overall, complications of Medpor, such as exposure or infection, are rare.

Polytetrafluoroethylene (Teflon®, Gore-Tex®, Proplast®)
Polytetrafluoroethylene (PTFE) is an inert and highly biocompatible polymer that is extremely useful in soft tissue augmentation but has limited use in bony repair due to its low tensile and compressive strength. Teflon, the first PTFE graft to be used in plastic surgery, is a chemically inert polymer used for soft tissue augmentation in the past, but the main application for Teflon has been orbital floor reconstruction. Gore-Tex is a pliable, durable, inert, biocompatible material that has some tissue ingrowth, little inflammatory reaction and almost no encapsulation. In addition to being used in abdominal fascial reconstruction, chest wall reconstruction and soft tissue reconstruction, Gore-Tex has also been utilized for lip, nasal, chin and malar augmentation. It has also been utilized for the treatment of nasolabial and glabellar creases. Proplast I is a highly porous, black graphite/PTFE composite with a spongy consistency. Because Proplast I led to discoloration of the surrounding soft tissues when implanted, Proplast II-a more rigid, white PTFE/alumina compound-was developed as an alternative. Proplast, with a wide variety of applications including the reconstruction of the chin, zygoma, orbital rim, maxilla, mandible, skull and rib cage, was originally regarded favorably. However, reports of biomechanical failure, intense inflammation, infection and extrusion related to the Proplast temporomandibular joint implant, led to the removal of all Proplast implants from American markets by the FDA in 1990.

Calcium Phosphate Ceramics
Calcium phosphate implants have been available as bone replacement/augmentation materials for 20 years. The primary calcium phosphates in clinical use are hydroxyapatite and tricalcium phosphate. These materials are osteoconductive (providing a scaffold for bone ingrowth) thus allowing for integration into the recipient site after placement. As a result, calcium phosphates are very well tolerated with essentially no inflammatory response, minimal fibrous encapsulation, and no adverse effects on local bone mineralization.

Metals
Metals have been used for the past 35 years for skull reconstruction and repair, in addition to reconstruction of craniofacial and upper extremity skeletal injuries. Stainless steel, cobalt-chromium (vitallium), pure titanium and titanium alloys are the principal metals currently available. Characteristics of a desirable metal implant include biocompatibility, strength, resistance to corrosion and imaging transparency.

Postoperative Considerations
Although numerous potential complications may occur with any implant-related procedure (e.g., migration, extrusion, palpability), the one common denominator shared by all alloplastic implants is their inherent risk of infection. The majority of postoperative infections appear within weeks to months after the initial surgery. Low-grade infections manifested only by fevers and signs of mild cellulitis are managed by intravenous antibiotics. More serious infections involving wound breakdown, implant exposure, gross purulence or systemic spread of the infection require prompt removal of the implant as antibiotics and drainage alone are usually insufficient. Reimplantation should not be performed for at least 3 to 6 months to allow for complete treatment and resolution of both the infection and the inflammation in the surrounding tissues. Several studies suggest that smooth, nonporous, nonresorbable implants have lower rates of infection, but it remains to be seen whether any true infectious risk differences exist among the various alloplastic implant materials available today.

Pearls and Pitfalls

Incisions should be placed as far as possible from the final position of the implant. This will decrease the risk of implant exposure or extrusion in the setting of a minor wound infection.
The implant should be covered with as much soft tissue as possible. The pocket should be of adequate size; too large and the implant will shift position, too small and the implant will be at risk for extrusion due to tension on the closure.
Whenever possible, always try and close a second layer of tissue between the skin and implant. This is critical if the implant lies directly beneath the incision.
Implants with sharp corners should be smoothed down, since sharp edges can erode through the skin with time.
The implant should be touched as little as possible. Clean, powder-free gloves should be worn and instruments should be used to handle the implant whenever feasible. The risk of infection and abnormal capsule formation is increased by the presence of any bacteria or foreign material on the implant.
Do not use an implant composed of a rigid material to replace soft, pliable tissue.
Keep an organized registry of all alloplastic implants in the event that the device fails or has to be removed. Give the patient a copy of the device name, model, manufacturer and serial number, in case failure occurs in the care of another physician.

Microvascular Surgical Technique and Methods of Flap Monitoring

2009-02-07T07:15:00.001-08:00

Introduction

The hand is capable of coordinated activity finer than the eye can direct. With the aid of magnification, the true capability of the hand can be exploited. As a tool for the plastic surgeon, microsurgery has allowed reconstructions that were simply not possible before. However, microvascular free tissue transfer is not a technique for the occasional microsurgeon. The catastrophic complication of flap failure looms over every microsurgical case; therefore, expertise in the execution of a free flap as well as its postoperative surveillance is key to a successful outcome.

Experience has shown that flap loss is a preventable complication and that elective microsurgery should have a failure rate of less than 2%. Most cases of flap loss are technical in nature. The fault may lie in the choice of flap, the harvest of the flap, preparation of donor vessels, insetting of pedicle or microsurgical technique. In general, it is best to think of all possible errors as additive in the process of thrombosis. Failure will occur if the procoagulatory factors outweigh the intrinsic ability of the vessels, in particular intact and uninjured intima, to prevent clot formation.

Flap Choice

The first step for success in microsurgery is flap choice. The specifics of different flaps are discussed in subsequent chapters. The most important determining factors for flap choice should be the surgeon’s experience and the goals of reconstruction.

In general, each surgeon should identify at least four flaps they feel comfortable with. These flaps should include a bulky muscle flap, a bulky fasciocutaneous flap, a thin fasciocutaneous flap, and a bone flap. With this armamentarium, the reconstructive surgeon will have tools that can be applied to most situations. By limiting himself to a small number of flaps, more experience can be obtained with each one. This increased experience translates to increased success. It is not advantageous to explore every novel flap that is reported, as this dilutes the experience and increases the chance of failure. With increasing experience with each flap comes increasing success and a lower failure rate.

This does not imply that specific flaps may not be beneficial over others in certain situations. There is no doubt that the donor properties of a latissimus dorsi flap differ from those of the gracilis flap and that each may be a better choice for a specific patient. However, the patient is best served with successful reconstruction. If there is significant benefit in a flap where the surgeon has no experience, the surgeon should consider referral or should seek additional training in order to add that flap to his or her armamentarium. This may include time in a cadaver lab or observing a surgeon with a particular skill.

Having mastered the tools of reconstruction, the surgeon should judiciously consider the requirements for reconstruction. Bulky muscle flaps are best for contaminated defects and bony injuries with high risk for infection. Thick fasciocutaneous flaps are useful for contour and shape reconstruction. Thin fasciocutaneous flaps provide stable, noncontracting coverage. Bone flaps provide structural integrity.

Specific aspects of each flap harvest are discussed elsewhere in this book. Certain principles, however, hold true despite the flap chosen. While harvesting a flap, the pedicle should be carefully dissected with as much length as possible. It is important not to limit the pedicle length to the anticipated need, but to harvest the maximum that can safely be obtained. It is much more advantageous to discard unneeded length than to find oneself requiring more pedicle length. Vein grafts should be avoided unless absolutely necessary.

While harvesting the flap and dissecting the pedicle, the most common mistake is damaging the vessels. Forceps should only touch the adventia and never purchase the vessel as the intimal layer is extremely fragile and easily fractured or crushed by manipulation. Any grasping of the vessels will cause damage to the intima which increases the likelihood of clot formation. This intimal injury leads to platelet deposition and thrombosis as the injured endothelial cell layer loses its natural thrombolytic properties.

Division of the pedicle should be reserved until the last possible moment. Prior to division, the donor vessels should be dissected, isolated, prepared and positioned for the anastomosis. It is helpful to mark the vessels in their natural state to assure that they are not twisted when transferred to the recipient site. Prior to division, the artery should be occluded first, followed by the vein. This will avoid excess blood pooling in the flap. Immediately after the flap is removed, one can consider cooling the flap with chilled saline as this decreases the metabolic activity of the tissue and allows the luxury of a longer ischemic time.

There is seldom a need to separate the artery and vein within the pedicle for anything more than a minimal distance. The only exception is the case where the recipient vessels are not paired. The vessels should not be skeletonized until they are brought to the recipient site and carefully prepared under the microscope. Any branches within 2 mm of the anastomosis are best sutured closed with microtechnique to avoid blood pooling near the anastomosis.

Preparation of Recipient Site

Preparing the recipient site mirrors the harvest of the flap. Vessels should be chosen that are simple to use and of the largest caliber available. They should be expendable when possible and have sufficient length. Again, care should be taken in the preparation of the vessels. They should not be extensively manipulated or injured. They should only be skeletonized for 2-3 mm around the anastomotic site, and this should be done under the microscope.

Microsurgical Technique

The anastomosis can be done in several fashions. These include end-to-end or end-to-side. They can be performed by multiple suture techniques or with coupling devices. The general philosophy is to gain experience with two or three techniques and apply those techniques to different situations. With careful planning, preparation, and mobilization of both the pedicle and recipient vessels, this is generally possible.

General principles of proper microsurgical technique are:

Pass sutures perpendicularly through the adventitia into the intima.
Avoid grasping or manipulating the intima.
Avoid multiple suture passes.
Avoid torquing the needle in the vessel; grasp and regrasp the needle in order to pass it through the vessel following the curve of the needle perfectly.
Dilate and visualize the inside of the vessels with heparinized saline irrigation on an ocular anterior chamber needle.
Use polished vessel dilating forceps to gently open spasmodic vessels or for vessel expansion.
Leave long tails on the sutures for manipulation and visualization.
Perform both anastomoses prior to reperfusion.
Release clamps on the vein first.
Inspect the anastomosis using the long suture tails as handles.
Place additional sutures in gaps with pulsatile or pressurized bleeding.
Avoid the temptation to place excess sutures in cases of mild oozing of blood from the anastomosis.
Apply warm saline to the flap and papaverine to the anastomosis after reperfusion to dilate the vessels and relax spasm.

Anastomotic Techniques

End-to-End

The end-to-end anastomosis is the simplest and the most reliable method. There are several techniques of suture placement including the 180˚-180˚ and triangulation methods. The easiest is probably the 180˚-180˚ technique. This can be applied to any situation and is probably the best technique for size-mismatched vessels.

Important points to remember are:

The vessels must not be twisted prior to placement in the double clamp holder. This can be ensured by inking one surface of the pedicle and recipient vessels prior to their division or dissection.
The first two sutures are placed at opposite poles of the vessels.
The third suture is placed midway between the poles.
In most cases, the next sutures bisect the gap though on occasion, two sutures will be needed in the gap.
Once the anterior wall is complete, twist the entire double clamp to show the backwall.
Visually inspect every suture of the anterior wall from the posterior view to assure that they are evenly spaced and have not purchased the back wall of the vessel.
Place another bisecting suture midway between the poles on the back wall.
All remaining sutures can be placed and left long (not tied).
Dilate the vessel with saline when tying the back wall to assure that there is no purchase of the anterior wall.

End-to-Side

The end-to-side technique is occasionally necessary. For example, it is used in the leg when there is only one vessel available or for an anastomosis in the head and neck (for example, to the internal jugular vein). Principles are:

The pedicle vessels should enter the recipient vessel at a gentle angle.
Perform a limited arterioectomy, removing a small window of vessel.
Place heel and toe sutures first.
Initially close the heel.
Follow with closure of the toe.

Coupling Devices

Coupling devices are useful for veins or thin-walled arteries. They save some time in the anastomosis. They, however, are not a panacea. The major time consumption in a microsurgical case is not the anastomosis, but the set up and preparation. If coupling devices are used, the set up and preparation time remain the same. Principles of gentle handling of vessels are still required as is avoidance of damage to the intima. Overall, the devices appear to have a place in the venous anastomosis, where they can also act as a stent, or in cases with significant size mismatch. Points to consider are:

Use the largest size coupler that will comfortably fit (range 2-3.5 mm).
Draping of the vessel over the spikes is performed by one surgeon while the other maintains the engagement of the spike as the vessel is seated.
Seat the vessel 180˚ apart to assure even spacing on the coupler.
Avoid grasping the intima of the vessel as it is draped over the spikes.
Assure that the coupling device is closed and guide it off of the coupling applier.

Draping of the Pedicle

After the anastomosis is complete and the flap is successfully revascularized, it is not uncommon for significant problems to arise. Kinking or unnatural curvature of the pedicle will certainly cause thrombosis. In fact, any turbulent, nonlaminar flow increases the likelihood of thrombosis and flap loss. The pedicle should be carefully draped. Gelfoam sponge or Alloderm can be used to help maintain the proper position of the pedicle.

Closure

A sound closure technique is again crucial for success. Both the flap and pedicle can be compressed by a tight closure. Anticipation of this is critical, as well planned incisions will allow closure after the edema of these long cases has set in. If there is any question, the liberal use of skin grafts to allow tensionless closure is recommended. The anastomosis should never be situated immediately under a suture line.

Monitoring

There is no “perfect” monitoring technique. Despite numerous ingenious techniques and improvements in technology, the ideal monitoring technique should be the one that surgeons and ancillary staff at a particular hospital are most familiar with and meet the restraints (budgetary or manpower) of the institution. What is ideal at one institution may not be practical at another. What is clear over many years of clinical experience, although this remains to be formally proven, is that the presence of dedicated staff in a dedicated unit stands the best chance of picking up problems earlier. The impetus to closely monitor a flap comes from the enormous investment undertaken on the part of the patient as well as the surgeon regarding microvascular free tissue transfer. The utility of postoperative flap surveillance has been proven, with an increase in the salvage rate of the failing flap from 33% to about 70% in some series.

The clinical exam is useful when performed by the experienced clinician. The transition of a healthy, plump flap or vibrant replanted digit to cold, flat, lifeless tissue can proceed via either arterial occlusion or venous congestion. These characteristics are useful in deciding whether to explore a flap or perhaps treat with leech therapy. Although it is the least technologically-based, much information can be gleaned from a thorough physical exam. Turgor can indicate the state of arterial inflow or venous outflow. Like a balloon, the flap or digit will inevitably declare itself if it has arterial insufficiency or venous congestion. Bleeding can be useful, as the qualitative and quantitative flow in response to pinpricks or rubbing of wound edges can declare the state of circulatory flow to the flap. In particular, a congested flap may bleed briskly, but the blood will appear dark and unoxygenated. The blood flow of a flap with compromised arterial inflow will be weak or absent. A caution regarding the pinprick test is that it is useful for evaluating a flap, but will occasionally cause trauma leading to vasospasm or hematoma in the confined space of a finger.

It is possible to monitor free flaps with a temperature probe. This method consists of placing surface temperature probes on the skin of the free flap and comparing them to probes placed on neighboring native skin. The probes are attached to a temperature monitor that will give off an alarm if there is a difference in temperature between the two sites greater than the specified amount (typically, 2-3˚C). Although appealing, there are limitations to the use of temperature probes, as the readings may be affected by regional changes in blood flow that are not secondary to flap flow disturbances.

Doppler ultrasonography is perhaps the most widely used monitoring tool. Two permutations exist. The first is the external Doppler. A recent innovation is the implantable internal Doppler. This tool permits monitoring of the segment of artery and vein a short distance downstream of the anastomosis. Its use has obviated the need for an external sentinel skin segment, and is ideally suited for buried anastomosis (e.g., jejunal free flaps in the head and neck, or vascularized bone transfers). These techniques are extremely useful; however, complications such as probe dislodgement and the occasional monitoring of an adjacent vessel that is not the pedicle can result.

In replants, the pulse oximeter is extremely useful. Some centers have reported success with fluorescein infusion and fluorescent lamp observation. This technique is not as useful in pigmented skin. Other techniques that at this time must be considered experimental include pH monitoring, duplex ultrasound, photoplethysmography, reflection photometry and radioisotope studies. None of these are currently widely used.

Pearls and Pitfalls

Although the microsurgical trainee may be eager to execute a large variety of occasionally exotic flaps, it is much more important to master a limited number of flaps and apply these flaps to different defects throughout the body. The principles outlined in this chapter serve as the basis to successfully execute any type of microsurgical transfer the plastic surgeon will encounter, even unusual flaps. In summary, it is essential to:

Sharpen microsurgical skills in the lab.
Handle the vessels gently.
Place significant attention on closure and pedicle position.
Familiarize oneself with one or two monitoring techniques. This will maximize salvage of the inevitable free flap failure.

The most important indicator of a problem with the free-flap is a change in the

clinical exam. This necessitates that the flap be seen as soon as possible by a surgeon who has been actively managing the patient.

Principles of Surgical Flaps

2009-02-07T06:56:00.003-08:00

Introduction

The underlying principle of all surgical flaps is the ability to maintain a viable blood supply upon transfer of flap tissue from a donor site to a recipient site. Given this fundamental capacity to retain vascular circulation, surgical flaps may be classified in many ways. One approach is by composition, as a flap may be made up of many different kinds of tissue. Another is by vascularity, and several different schemata have been developed to categorize flaps by the type of vascular supply. A third manner of categorizing flaps is by method of movement, and it is important to understand the basic techniques of flap transfer. Unlike a graft, which is wholly dependent upon the recipient bed to provide blood supply, a flap by definition is able to preserve its own vascular supply for survival. Thus, whether classifying a flap by composition, vascularity or method of movement, the core principle essential to all flaps is how to maintain blood supply so that the flap tissue will remain robust after transfer to its new site.

Composition

The most basic way to think about a flap is to consider what tissues are contained within it. A flap may contain skin, fascia, muscle, bone or various combinations of these tissues. As the underlying principle of any flap is its ability to retain its own blood supply, the amount of tissue that may be carried within it is dictated by the minimum or maximum amount of tissue that can be transferred with intact vascularity. When more than one type of tissue is contained within a flap, it is called a “composite flap.”

The simplest type of flap is the skin flap. The blood supply of the skin is contained largely in the dermal and subdermal plexus and derives from two main sources: a musculocutaneous vascular system and a direct cutaneous vascular system. When the blood supply to the skin is via a named artery, the skin flap is called an “axial flap.” When the blood supply to the skin lacks a significant pattern in its vascular design, the skin flap is called a “random flap.” Either way, the survival of a cutaneous flap depends on the number and type of blood vessels at the base of the flap. For an axial flap, the survival pattern of the flap is based on the length of the underlying feeding artery. For a random pattern flap, the length and width should be designed in a 2:1 ratio, as a wider base width increases the chance that a large vessel will be incorporated to provide an adequate blood supply to the enclosed dermal-subdermal plexus. Even in an axial flap, the distal borders of the flap are also random pattern with distal perfusion from the dermal-subdermal plexus .

Skin flaps may also be transferred based on the vascular plexus of the deep fascia, in which case they are termed “fasciocutaneous flaps.” The blood supply of the deep fascia is derived from perforating vessels of regional arteries that pass along the fibrous septa of muscle bellies or muscle compartments. Including the deep fascia along with the skin avoids tedious dissection and may also preserve adjacent subfascial arteries. Among the advantages of fasciocutaneous flaps in reconstructive surgery are ease of elevation and transfer, decreased bulk, good reliability, and decreased functional morbidity at the donor site. Depending on the size of the skin paddle, however, the secondary defect at the donor site may require coverage with a split-thickness skin graft.

Progressing one layer deeper still, another common flap in reconstructive surgery is the “myocutaneous” or “musculocutaneous” flap, which combines muscle, skin, and the intervening fascia and subcutaneous tissue. Supplied by one or more dominant vascular pedicle within the muscle instead of a direct cutaneous arterial source, the essential feature of a myocutaneous flap is that the underlying muscle “carries” the blood supply for the overlying skin. Myocutaneous flaps have two key advantages. First, the increased bulk better allows it to fill dead space. Secondly, myocutaneous flaps are also more resistant to bacterial infection than fasciocutaneous flaps by a factor of 100. This makes them very reliable and useful, particularly when increased bulk is needed with a robust arterial supply to fill a defect that has been subjected to chronic infection. If a skin paddle is not needed, muscle can also be transferred alone, without the overlying fascial and cutaneous tissue.

A final type of tissue commonly incorporated into a flap is bone. When taken with the overlying skin, this is called an “osseocutaneous flap.” A dominant vascular pedicle with perforating branches supplies the skin and periosteum. Usually taken as a free flap, the bone is harvested with a cuff of muscle and/or skin to reconstruct a skeletal framework with soft tissue. The long bones of the extremities, such as the fibula, are often used as they provide more length for shaping according to the required need.

Type of Blood Supply

Once the composition has been determined, flaps can be further categorized according to their blood supply. As mentioned earlier, random flaps are based primarily on the cutaneous blood supply from the dermal-subdermal plexus. Pedicled or axial flaps are based on anatomically mapped or named blood vessels.

Fasciocutaneous flaps have been classified into three categories based on their vascular patterns.

Type A: Direct cutaneous pedicle

Type B: Septocutaneous pedicle

Type C: Musculocutaneous pedicle Muscle flaps may be classified in two different ways. First, Mathes and Nahai developed a system of muscle classification based on circulatory patterns.

Type I: Single pedicle (e.g., tensor fascia lata)

Type II: Dominant pedicle(s) with minor pedicle(s) (e.g., gracilis)

Type III: Dual dominant pedicles (e.g., gluteus maximus)

Type IV: Segmental pedicle(s) (e.g., sartorius)

Type V: Dominant pedicle, with secondary segmental pedicle(s) (e.g., latissi

mus dorsi) Second, Taylor developed a system of muscle classification based on mode of innervation.

Type I: Single, unbranched nerve enters muscle (e.g., latissimus dorsi)

Type II: Single nerve, branches prior to entering muscle (e.g., vastus lateralis)

Type III: Multiple branches from the same nerve trunk (e.g., sartorius)

Type IV: Multiple branches from different nerve trunks (e.g., rectus abdominis)

Finally, the body can be further segregated anatomically into three-dimensional vascular territories called “angiosomes.” The angiosome is a composite unit of skin and underlying deep tissue that is supplied by a source artery. Each angiosome defines an anatomic unit of tissue from skin to bone that may be safely transferred as a composite flap. The angiosomes are interconnected by either true anastomotic arteries, in which there is no change in caliber between the vessels of adjacent angiosomes, or reduced-caliber, choke anastomotic vessels. The junctional zone between adjacent angiosomes usually occurs within the muscles of the deep tissues rather than between them, so that most muscles span across two or more angiosomes. Thus, when designing musculocutaneous flaps it is possible to capture the skin island from one angiosome by using muscle supplied from the adjacent angiosome.

Flap delay is defined as the surgical interruption of a portion of the blood supply in a preliminary stage prior to tissue transfer. The purpose of delay is to augment the surviving portion of the flap. There are two schools of thought regarding the pathophysiology of the delay phenomenon. The first holds that delay conditions tissue to ischemic conditions so that it is able to survive with less vascular inflow. The second believes that delay actually increases vascularity by dilating reduced-caliber choke anastomotic vessels and stimulating additional vascular ingrowth.

Another way to increase survival of a myocutaneous flap is by supercharging the blood supply. This method involves augmenting arterial inflow by using microsurgical techniques to bring in an additional vascular pedicle. Classically described for use in a pedicled TRAM flap, the supercharging technique may be performed in one of two ways. First, in the pedicled TRAM flap, the contralateral deep inferior epigastric vessels may be retained in a cuff of inferior rectus muscle in a planned vascular augmentation to a single-pedicle flap. Alternatively, the inferior epigastric vessels on the pedicled side may be used to save a flap during the immediate postoperative period in an emergency “supercharged” TRAM flap.

Techniques of Flap Transfer

The final way to categorize flaps is by the technique of flap transfer. Broadly speaking, flaps can either be pedicled flaps or free flaps. Pedicled flaps remain attached to the underlying blood supply, while the tissue connected to it is transferred to another site. Free flaps are temporarily disconnected from their blood supply, and then the feeding vessels are surgically anastomosed to the blood supply at the recipient site. Flaps can be further categorized by the distance between the donor site and recipient site. Local flapsare used to close defects adjacent to the donor site. Distant flaps imply that the donor site and the recipient site are not in close proximity so that closure cannot be facilitated by a local method.

There are several different types of local flaps. An advancement flap moves along an axis in the same direction as the base to close the defect simply by stretching the skin. Examples of an advancement flap are the V-Y flap, Y-V flap, and the bipedicled flap (. A rotation flap has a curvilinear design and rotates about a pivot point to close a wound defect. The donor site is closed primarily by reapproximating the skin edges or with a skin graft. A back cut in the direction of the pivot point can be made to facilitate closure, but this can also compromise the blood supply to the flap by decreasing the base width. A Burow’s triangle can also be made external to the incision to decrease tension and facilitate primary closure of the donor site . Finally, atransposition flap is a rectangular flap that is rotated laterally about a pivot point into an adjacent defect to be closed. The farther the flap rotates, the shorter the effective length of the flap, so that the flap must be designed longer than the defect in order to close the donor site. Otherwise, the donor site may be closed primarily with a skin graft or with an additional transposition flap, as in a bilobed flap .

There are several important types of transposition flaps. The first is the Z-plasty, in which adjacent triangular flaps are interchanged to exchange the width and length between them. The three limbs of the Z must be equal in length, and the amount of length obtained depends upon the intervening angles, with 60˚ being the classic angle to obtain optimal increase in length while preserving blood supply to the triangular flaps . The rhomboid or Limberg flap is another type of transposition flap that can be used to close a skin defect. Four different flaps can be designed at angles of 60˚, with the longitudinal axis paralleling the line of minimal skin tension . The Dufourmentel flap is like the rhomboid flap, except the angles are at 90˚. Finally, the double opposing semicircular flap can be used to close circular skin defects .

Interpolation flaps also rotate about a pivot point, but they are either tunneled under or passed over intervening tissue to close a defect that is not immediately adjacent to the donor site. Examples include the Littler neurovascular island flap and the pedicled TRAM flap.

Distant flaps involve tissue transfer from one part of the body to another in which the donor site and the recipient site are not in close proximity to each other. There are three types of distant flaps: direct flaps, tubed flaps and free flaps. The direct flap involves the direct transfer of tissue from a donor site to a distant recipient site. Examples of direct flaps include the thenar flap, cross-leg flap and groin flap. Tubed flaps are used when tissue cannot be directly approximated, so that tissue from the donor site is tubed to recipient site. Once the vascular supply has been established, the tube is divided and tissue from the tube is returned to donor site. Examples of this are the forehead flap and the clavicular tubed flap. Finally, free flaps involve complete disconnection of the underlying blood supply, so that the blood vessels from transferred tissue must be surgically reanastomosed to reestablish vascular circulation.

Summary

In sum, the underlying principle of all surgical flaps is the meticulous preservation of blood supply. Unlike grafts, a flap carries its own vascular circulation with it.

The amount and type of tissue that a flap can contain is wholly dependent on the maintenance of adequate blood supply. Knowledge of vascular anatomy is crucial to flap design. Techniques of flap transfer must take care to safeguard the vascular circulation of the flap. With the careful protection of blood supply, it is possible to successfully plan and implement any surgical flap.

Pearls and Pitfalls

The success or failure of a flap is dependent upon blood supply. The ingrowth of new blood vessels from the surrounding tissue occurs over several weeks. As a general rule, the tissue that is most distant from the arterial inflow is at the highest risk of necrosis. Efforts to reduce this risk include the following: (1) preferentially discarding excess tissue from the distant tip; (2) for skin flaps, designing a flap with as broad a base as possible, away from any previous incisions sites; (3) minimizing tension; (4) maximizing inflow.

When designing a flap for covering or filling a defect, it is prudent to follow the carpenter’s rule of “measure twice, cut once.” Defects must be examined and measured three-dimensionally, since the width, depth and length will not always conform to a two-dimensional plane. The final desired contour should also be considered (e.g., if a convex contour is desired, the length of the flap should be greater than the direct length of the defect). Furthermore, it should be determined whether or not moving adjacent structures (such as the arms or legs) will change the dimensions of the defect. For instance, a supraclavicular skin defect will significantly increase in size when the patient’s head is turned away from the defect.

Principles of Reconstructive Surgery

2008-08-16T02:51:00.000-07:00

Introduction

Plastic and reconstructive surgery is a field that relies upon basic principles to restore form and function to the human body. Whether it is a gunshot wound to the face, a congenital hand deformity, or a malformed breast, plastic surgeons must be adept at adapting a fundamental knowledge of human anatomy and physiology to create ingenious solutions to ever-changing challenges. Unlike techniques which must be modified with each new advance in medical technology, the use of principles makes it possible for the plastic surgeon to address problems as varied as the infinite diversity of the human species. Rote memorization of operative steps and mathematical formulas are insufficient. The reconstruction of the human body depends upon the ability to devise creative solutions based on core principles. Over the years, numerous efforts have been made to categorize these principles. Despite changes in technique, the fundamental principles of plastic and reconstructive surgery have withstood the test of time.

Ambrose Paré

The earliest principles of reconstructive surgery may be attributed to the French surgeon, Ambrose Paré, who in 1564 published five basic principles of plastic surgery. The first principle was “to take away what is superfluous.” Whether applied to the excision of redundant tissue or the complete amputation of a surplus structure such as a digit or a supernumerary nipple, this first principle emphasized the need to eliminate that which served no purpose. The second principle was “to restore to their places things which are displaced.” Whether applied to a congenital deformity, such as a cleft lip, or an acquired deformity, as in trauma, this principle required recognition of normal parts and diagnosis of the abnormal position. Likewise, the third and fourth principles, “to separate tissues which are joined together,” and “to join those tissues which are separate,” also required the ability to conceptualize a hypothetical norm. Indeed, a given defect could often be determined accurately only after distorted tissue was returned to its normal shape. This was true whether applied to a congenital defect, such as syndactyly, or an acquired defect, such as a burn contracture. Finally, the fifth principle, “to supply the defects of nature,” also required the ability to visualize restoration to a normal state.

Modern Plastic Surgery: Gillies and Millard

Building upon these early ideas, Sir Harold Gillies and D. Ralph Millard took the principles of Paré to the next level. Recognizing that the remodeling of human tissue was different from clay, Gillies and Millard took as their founding principle

Table 10.1. Gillies’ ten commandments of plastic surgery

Thou shalt make a plan.
Thou shalt have a style.
Honor that which is normal and return it to normal position.
Thou shalt not throw away a living thing.
Thou shalt not bear false witness against thy defect.
Thou shalt treat thy primary defect before worrying about the secondary one.
Thou shalt provide thyself with a lifeboat.
Thou shalt not do today what thou canst put off until tomorrow.
Thou shalt not have a routine.
Thou shalt not covet thy neighbor’s plastic unit, handmaidens, forehead flaps, Thiersch grafts, cartilage nor anything that is thy neighbor’s.

that “plastic surgery is a constant battle between blood supply and beauty.” That is to say, the reshaping of human structures demanded that its vitality as living tissue be respected. Drawing upon the wisdom of his mentor, Sir Harold Gillies, Millard produced one of the most widely recognized efforts to outline the principles of reconstructive surgery. In 1950, Millard codified rules learned from Gillies and published them as the “ten commandments” of plastic surgery (Table 10.1). Shortly thereafter, the pair expanded these ideas to 16 principles that would apply not only to plastic surgery problems but also to a philosophy of life in general. Millard went on to develop the concept of principles still further in his classic tome, Principalization of Plastic Surgery. Divided into four broad sections, this work offered 33 commonsense rules to help plastic surgeons fashion answers to a variety of surgical problems.

Preparational Principles

Millard’s first 12 principles fell under the framework of “Preparational Principles”-that is, principles to keep in mind before making the opening incision. The first principle was to “correct the order of priorities.” Applied broadly, this could mean emphasizing integrity and ethics; it could mean prioritizing function over form; and it could also mean performing a blepharoplasty before a facelift since the latter could affect the former but not vice versa. The bottom line was that whether in life or in a specific procedure, each part needed to be considered in the context of the whole.

The second principle was that “aptitude should determine specialization,” meaning that the plastic surgeon should play to strengths when deciding whether to focus on reconstructive surgery, cosmetic surgery, microvascular surgery, craniofacial surgery, head and neck oncology, hand surgery, burn physiology or laboratory research. Millard emphasized that a person who initially appeared inept in one area could later progress to excel above all others in the same area. Using himself as an example, Millard revealed that he took an aptitude test early in his career that determined that he would be well-suited to writing and possibly medicine, but completely unsuited for surgery due to a perceived inability to visualize objects in three dimensions. Despite this, he went on to become one of the most accomplished plastic surgeons in history, known especially for the three-dimensional rotation-advancement flap that is the standard of care for cleft lip repair today.

The third principle was to “mobilize auxiliary capabilities.” That is to say, the plastic surgeon should incorporate individual talents to develop a “personal style with individual flair.” Advised to develop one primary capability and several secondary talents such as sculpture, music, writing or painting, the ideal plastic surgeon would be multi-talented for maximal depth and versatility in the operating room. The fourth principle was to “acknowledge your limitations so as to do no harm,” a self-evident principle that spoke to the temptation to persevere on a case with endless complications. Instead, the successful surgeon should know when to stop. The flip side of this was the fifth principle, which was to “extend your abilities to do the most good.” This spoke to the moral obligation to use plastic surgical training to alleviate human suffering, that is, to reconstruct mutilated or severely deformed patients instead of limiting one’s practice to purely aesthetic procedures. The sixth principle was to “seek insight into the patient’s true desires.” Delving into the psyche, this principle directed the plastic surgeon to decipher a patient’s actual problems instead of merely taking the stated problem at face value to preempt patient disappointment, improve public relations and prevent postoperative legal complications.

The seventh principle was to “have a goal and a dream.” In plastic surgery, this principle shifted depending on whether a procedure was primarily cosmetic, in which the goal would be to surpass normal, or primarily reconstructive, in which the goal would be to attain normal. Either way, the plastic surgeon should have a target in mind before beginning an operation. The eighth principle was to “know the ideal beautiful normal.” While this ideal beautiful normal could vary among different ethnic backgrounds, it was important for the plastic surgeon to be able to define it in order to attain pleasing aesthetic proportions and visual harmony.

The ninth principle was to “be familiar with the literature.” Knowing what had already been described assisted a surgeon in discriminating between procedures that would and would not be successful; it also gave the surgeon access to a collective bank of experience that allowed extension beyond what one person could accrue in a lifetime. The tenth principle, to “keep an accurate record,” was like the sixth principle in that its underlying purpose was both to further patient care and provide legal protection for the surgeon. In addition, since memory was inherently unreliable, accurate written and photographic records provided baseline references that allowed the plastic surgeon to coordinate multi-staged procedures to achieve a successful final result.

The eleventh principle was to “attend to physical condition and comfort of position.” Often overlooked by single-minded surgeons, the basis of this principle was the belief that the optimal surgical performance depended upon good physical condition and a comfortable working position for the surgeon. Finally, the twelfth principle, “do not underestimate the enemy,” acknowledged that peril lay behind every procedure. Thus, whether the enemy was hypertrophic scar formation or inadequate vascular supply, it was never possible to be overly vigilant in preventing surgical complications.

Executional Principles

The second category of principles addressed the wielding of the blade. The thirteenth principle, “diagnose before treating,” emphasized that observation was the basis of surgical diagnosis. The plastic surgeon must use all senses—particularly visual and tactile cues—to accurately determine a problem before proceeding with an operation. The fourteenth principle was reminiscent of Paré, in that it advised the plastic surgeon to “return what is normal to normal position and retain it there.” As previously mentioned, displacement of structures could be due to failure in normal embryonic development or as a direct result of trauma, ablation, scar contraction, or even the aging process, but correction required the ability to recognize the norm in order to restore displaced parts to their correct place.

The fifteenth principle stated that “tissue losses should be replaced in kind.” More specifically, when attempting reconstruction of lost body parts, bone should be replaced with bone, muscle with muscle and glabrous skin with glabrous skin. If exact replacement was impossible, then a similar substitute should be made, such as a beard with scalp, thin skin for an eyelid, thick skin for the sole of a foot, and a prosthesis for an eye. The idea was that replacing like with like would give the most natural outcome. The sixteenth principle advised the plastic surgeon to “reconstruct by units.” By basing reconstruction on unit borders demarcated by creases, margins, angles and hairlines, surgical scars could often be concealed by the meeting of light and shadow.

The seventeenth principle was to “make a plan, a pattern and a second plan (lifeboat).” By visualizing an entire operation from beginning to end, the plastic surgeon could anticipate possible difficulties and then proceed to devise a secondary plan for use should the primary plan fail. The eighteenth principle was to “invoke a Scot’s economy.” This involved thrift in surgery, in which no tissue was ever discarded until it was certain that it was no longer needed. A corollary of this was to discard the useless, as once a piece of tissue was determined to have no further value it should be removed—but refrigerated storage was advised even then in case the tissue could be used later.

The nineteenth principle was to “use Robin Hood’s tissue apportionment.” That is, Robin Hood would steal from the rich to give to the poor. Likewise, this principle advised using excess tissue to make up for areas with tissue deficits by rotating, transposing, or transplanting expendable tissue flaps to areas in need. The corollary to this was the twentieth principle, to “consider the secondary donor site.” That is, while reconstructing deficient areas with tissue taken from areas that were more ample, the resulting secondary defect must also be considered to make sure that its sacrifice was not too deforming. The twenty-first principle was to “learn to control tension.” In opening, tension usually facilitated a clean cut with the scalpel; in closure, tension could lead to tissue necrosis or excess scarring; in flap design, skin tension lines could be identified and used to camouflage scars. The twenty-second principle was to “perfect your craftsmanship.” For the plastic surgeon, “good” suggested mediocrity, and nothing short of perfection was acceptable. The twenty-third and final executional principle was “when in doubt, don’t!” Doubt should function as a deterrent, and if a solution to a problem left seeds of doubt, it was better to develop a better idea.

Innovational Principles

The third category of principles governed the generation of new concepts in plastic surgery. The twenty-fourth principle was to “follow up with a critical eye.” That is, it was important to follow patients postoperatively over time to critically evaluate results, as regular review of one’s handiwork was the best way to spur advancement and improvement of surgical procedures. Likewise, the twenty-fifth principle, to “avoid the rut of routine,” exhorted surgeons to shun mindless and tenacious clinging to unthinking rituals. Again, by thinking outside the box, the plastic surgeon could make the advance to the next level of innovation and development. The twenty-sixth principle, “imagination sparks innovation,” was the “breakthrough” or problem-solving principle that encouraged free-spirited thinking and creativity.

The twenty-seventh principle, “think while down and turn a setback into a victory,” was labeled the “prince of principles” by Millard. It admonished the surgeon not to panic or despair, or compound error when faced with possible defeat. Instead, the surgeon should keep cool while determining the cause of loss, expend no energy in worrying about a compromised position, and make certain not to repeat the same mistake while thinking one’s way to recovery. Finally, the twenty-eighth principle was to “research basic truths by laboratory experimentation.” By testing even minor theories in the laboratory, the surgeon could discover answers to plastic surgical questions in a controlled setting.

Contributional Principles

The fourth set of principles governed ways to contribute to the field of plastic surgery. The twenty-ninth principle was to “gain access to other specialties’ problems.” By consulting with physicians or surgeons from other specialties, it could be possible to learn management of common complications that would both benefit patients as well as broaden the base of plastic surgery. The thirtieth principle was that “teaching our specialty is its best legacy.” The implication was that the best way to extend plastic surgery was to transmit knowledge via lectures, books, symposiums and personal experiences to ensuing generations. The thirty-first principle was to “participate in reconstructive missions.” Moreover, the ideal method to conduct such missions was to lend specialists not just to operate, but to teach people in underdeveloped countries how to perform the operations and manage all the postoperative care themselves.

Inspirational Principles

The final set of principles attempted to prod the plastic surgeon to strive for perfection. Toward this end, the thirty-second principle was to “go for broke!” That is, the plastic surgeon should use every means possible to overcome obstacles, strive for the very best, and seek perfection. The thirty-third and last principle was to “think principles until they become instinctively automatic in your modus operandi.” By incorporating principles constantly and consistently into plastic surgical practice, it would become second nature to avoid rote memorization of techniques and instead stimulate the imagination to engage in innovative problem solving.

The Reconstructive Ladder

The traditional approach to the reconstruction of a variety of defects is based on the concept of the reconstructive ladder (Fig. 10.1). The basic notion is that one should use the simplest approach to solving a reconstructive problem, before advancing up the ladder to a more complex technique. Consequently, if the procedure fails, one can climb to the next level of complexity. For example, a lower extremity venous stasis ulcer should be treated by dressing changes alone or by a split-thickness skin graft if these are applicable. A more complex reconstruction with a free flap should be reserved as a last resort if all simpler options have been ruled out or have failed. More recently, however, experienced reconstructive surgeons are beginning to realize that certain problems are not amenable to simple solutions. In select cases, bypassing the lower rungs of the reconstructive ladder and proceeding directly to microvascular free tissue transfer is the optimal approach. A good example of this is post-mastectomy breast reconstruction. For many surgeons, the free TRAM or DIEP flaps have become the standard of care.

Pearls and Pitfalls

Plastic surgery takes passion, determination and sacrifice. As plastic surgeons, we would like to create perfection. Yet techniques and procedures are always evolving, so the operative process must be based upon principles. Without a commitment to perfection, a concept of what beauty is, and what the end result will be ahead of time, the surgeon is lost. Poets can be our role models, because poets are creative and can help show us how to get going with the creative process. Ultimately, however, plastic surgery involves sacrifice, focus, determination and, above all, will power. When these qualities are combined, the plastic surgeon is able to elevate the work that is performed. A person who is able to go to work and create something close to perfection, striving for perfection, will lead a very satisfying life. By its very nature, then, plastic surgery gives us the opportunity to enjoy that ideal life.

Surgery under Conscious Sedation

2008-08-16T02:47:00.000-07:00

Introduction

Conscious sedation is a technique that combines the use of local anesthesia and intravenous sedation. It is defined as a depressed level of consciousness to the point that the patient is in a state of relaxation, but maintains respiratory drive and the ability to protect the airway. The patient is also capable of purposefully responding to physical and verbal stimulation. This is in contrast to deep sedation, in which the patient is unable to respond to verbal stimuli, will only respond to painful stimulation with withdrawal and has potential compromise of airway protection and respiratory drive. As opposed to monitored anesthesia care (MAC), in which an anesthesiologist or nurse anesthetist are required, conscious sedation can be performed by a nurse under the supervision of the operating surgeon.

Conscious sedation is rapidly gaining acceptance and popularity among plastic surgeons. It has been utilized for many years by other specialties, and now with the growth in office-based procedures and surgicenters, there has been a corresponding increase in the role of conscious sedation. Currently, almost all aesthetic procedures can be performed using a local anesthetic combined with some form of intravenous sedation. These include breast augmentation, breast reduction, mastopexy, abdominoplasty, rhytidectomy, rhinoplasty, blepharoplasty and liposuction.

Benefits and Disadvantages of Conscious Sedation

There are a number of benefits to the use of conscious sedation instead of general anesthesia or deep sedation. First, the complications associated directly with the administration of a general anesthetic are avoided. These are not negligible, and include adverse cardiopulmonary effects, airway injury and positional nerve injuries. Such complications occur in roughly 1-2% of aesthetic procedures performed under general anesthesia. The incidence of postoperative nausea and vomiting, which account for most unintended admissions after outpatient surgery, is much less than that associated with general anesthesia. Secondly, the risk of developing deep vein thrombosis (DVT) as a result of blood pooling in the lower extremities during general anesthesia is greatly reduced due to the continued contraction of leg muscles and the spontaneous shifting of the patient during the procedure. Third, as a result of the relatively large dose of an amnestic medication that is used, most patients have no memory of the procedure, no recollection of experiencing pain, and many choose to undergo conscious sedation at subsequent procedures. Finally, because it can be performed safely without the presence of an anesthesiologist, there is a considerable saving in cost to the patient.

Conscious sedation is not suited to all patients. Furthermore, the use of conscious sedation requires a surgeon who can “multi-task,” focusing on the operation

as well as on the vital signs and level of arousal of the patient. The fact that the patient is conscious and can shift position or move freely, necessitates that the surgeon be prepared to stop working at any moment. Nevertheless, many patients are well-suited for conscious sedation.

Preoperative Considerations

Prior to using conscious sedation for the first time, the surgeon must familiarize herself with the medications she will be using, as well as their side effects and reversal agents. She must also be familiar with ACLS protocol, airway management and have readily available resuscitation equipment. Immediate access to an anesthesiologist in case of emergency is strongly recommended.

Proper patient selection is an important preoperative decision. Those with moderate to significant cardiopulmonary disease are poor candidates. Patients should meet the criteria of the American Society of Anesthesiologists status I or II. This means that candidates for conscious sedation should be healthy or have only a mild systemic disease that results in no functional limitation (e.g., obesity, diabetes, hypertension and extremes of age). All other patients should receive monitored anesthesia care by an anesthesiologist or general anesthesia. Furthermore, individuals with anxiety disorders and extreme fear of the operating room may not be suited for conscious sedation.

Prior to the procedure, patients may benefit from premedication with intravenous diazepam (Valium), administered in increments of 5-10 mg. The dose administered usually ranges from 10 to 50 mg, with the goal being adequate preoperative subjective relaxation of the patient with the desired endpoint being of slurred speech. Oral diazepam is also an option; however, it has to be given almost an hour prior to the procedure in order to be effective. A second medication that should be administered preoperatively is an antiemetic. Ondansetron (Zofran), given as a single 4 mg intravenous injection is used routinely at our institution. Recently, we have found that clonidine (0.1-0.3 mg PO) given 30 minutes prior to the procedure is not only effective in lowering blood pressure during surgery, it also contributes significantly to patient relaxation during the procedure. It does, however, cause post-procedure orthostatic hypotension.

Intraoperative Considerations

Tumescent Anesthesia

As stated previously, conscious sedation—as it pertains to plastic surgery, involves the administration of local anesthesia in addition to the intravenous sedation. In fact, it is the methodical use of tumescent anesthesia that ensures a smooth, relatively pain free procedure. Tumescence, or wetting solution as it is more appropriately termed, should be infiltrated into the surgical field. Two goals should be kept in mind: anesthesia of the sensory nerves and vasoconstriction of the blood vessels in the region. Achieving these goals requires at least 10 minutes for the wetting solution to exert its effects. Two solutions are commonly used at our institution:

Liposuction solution 1 liter bag of Lactated Ringer’s solution

50 ml of 1% plain lidocaine

1 ml of epinephrine (1:100,000)

Face/breast solution 250 ml bag of normal saline

100 ml of 1% lidocaine + epinephrine (1:100,000)

10 ml of sodium bicarbonate

Table 9.1. Simple medication regimen that can be used for conscious sedation

Medication Dosage Range Purpose Reversal Agent Preoperative

Diazepam 5-10 mg Preoperative Flumazenil (0.2 mg/min; (up to 50 mg) sedation up to 5 doses; reversal in 1-2 min)

Ondansetron 2-4 mg Prevention of None postop nausea and vomiting

Intraoperative

Midazolam 0.5-2 mg Anxiolytic, Flumazenil (0.2 mg/min; sedative up to 5 doses; reversal in 1-2 min)

Fentanyl 12.5-50 mcg Analgesia Naloxone (0.1-0.2 mg/ 2 minutes) reversal in 2-3 minutes

Intravenous Sedation Regimens

Although there are a number of intravenous sedation regimens available, an excellent choice is the combined use of midazolam (Versed) and fentanyl (see Table 9.1). The advantage of using this combination is that midazolam has both anxiolytic and amnestic effects, whereas fentanyl is a potent, short-acting analgesic. The combination of fentanyl and midazolam is superior to midazolam alone in decreasing patients’ subjective report of pain and anxiety. The main drawback of fentanyl is respiratory depression; however unlike other commonly used intravenous opiates such as morphine, it does have a very short half life. Midazolam, in contrast, has minimal effects on the respiratory system except in the elderly, in which lower doses should be utilized. Both of these medications have antagonists. Flumazenil (Mazicon) and naloxone (Narcan), the antagonists of midazolam and fentanyl respectively, should be readily available in the operating room.

Another method of intravenous sedation involves the use of propofol in combination with an opiate and benzodiazepine. The fact that a deeper level of sedation can be maintained makes this technique preferable for selected patients who are very anxious. Nevertheless, the disadvantage of this combination is the higher risk of respiratory depression, and the lack of a reversal agent for propofol. This technique necessitates a higher degree of experience and training in anesthetic technique including the ability to intubate the patient if needed. The use of propofol is not discussed in this chapter.

In the operating room, one nurse should be responsible for continuously monitoring patient status using pulse oximetry, blood pressure and cardiac monitoring. This should be performed by a nurse with appropriate experience and background in continuous patient monitoring; however specialized anesthesia training is usually not needed. It is important to emphasize that this nurse should have no other duties to perform during the procedure. The patient’s oxygen saturation, blood pressure, heart rate, level of arousal and respiratory status should be monitored every 5 minutes. Changes in vital signs, level of arousal and the oxygen saturation are communicated to the surgeon. In addition, the surgeon should make his own assessment of arousal based on response to verbal stimulation, as well as the patient’s degree of discomfort.

Based on the patient’s condition, 0.5 to 2 mg of midazolam should be administered at the 5 minute intervals. In addition, fentanyl should be given in increments of 12.5 to 50 mcg. After local anesthetic is infiltrated, fentanyl administration is infrequently required, except in preparation for subsequent local anesthetic administration to a new surgical site. The total dose of fentanyl should rarely exceeded 200 mcg over the course of the procedure. Toward the end of the case, the amount of sedation should be decreased to allow the patient to slowly return to a normal state of arousal and awareness.

During conscious sedation, supplemental oxygen is usually not necessary. The ability of the patient to maintain an oxygen saturation over 95% without supplemental oxygen is a useful guideline to avoid oversedation (crossing from conscious to deep sedation). Occasional periods of deep sedation may occur, usually lasting for a few minutes at most. Brief stimulation and rarely jaw thrust may be required to maintain adequate ventilation. The use of small incremental doses of midazolam, limited use of narcotics and effective local anesthesia help to limit episodes of deep sedation. Nevertheless, as a safety measure, the capability to convert to general anesthesia or immediate assistance from an anesthesiologist should always be available. Foley catheters and sequential compression devices are generally not required due to the relatively short length of procedures utilizing conscious sedation, and the fact that venous stasis is minimal due to spontaneous patient movement and leg muscle contractions. For cases involving large volume liposuction or those that are longer than a few hours, a Foley catheter should be used to monitor fluid status and to allow greater flexibility in intraoperative fluid resuscitation.

Postoperative Considerations

Following the procedure, many hospitals will allow patients to bypass the recovery room and proceed directly to the outpatient day surgery area. This saves the patient the extra costs of recovery room care. Patients are monitored postoperatively in a standard manner. Those who choose to go home the day of surgery must meet criteria for discharge (ability to ambulate to a chair and the bathroom, bladder control, tolerate oral intake without emesis). Patients who received preoperative clonidine must be monitored for orthostatic hypotension.

Inpatient stay in an observation unit is appropriate for longer cases that involve multiple procedures, as well as for older patients who live alone. Postoperative nausea and vomiting is the major factor contributing to unintentional hospital admission after outpatient surgery. It begins shortly after arrival in the recovery room and usually lasts no longer than 12-24 hours postoperatively. A number of studies support the administration of a preoperative antiemetic (see preoperative considerations).

Pearls and Pitfalls

One of the risks of conscious sedation is crossing over into deep sedation. The responsible surgeon and monitoring nurse should be able to identify and handle patients who briefly slip into deep sedation. In very rare instances, a patient may require jaw thrust, mask ventilation or narcotic reversal. It is critical that the surgeon be comfortable performing these steps if necessary. A common pitfall leading to over sedation is to administer excessive amounts of fentanyl, instead of maximizing the use of the local anesthetic. Towards the end of the procedure, there is nothing wrong with cutting back on the amount of sedation, and allowing the patient to become more awake. In addition, excessive administration of versed can result in the opposite effect: an overly anxious, and occasionally claustrophobic patient. When this occurs, it is best to withhold sedation, reassure the patient and allow her to reorient herself.

Basic Anesthetic Blocks

2008-08-16T02:45:00.000-07:00

Introduction

Regional anesthetic blocks can be a valuable supplement or even replacement to the more common field block used in plastic surgery. The principle behind a regional nerve block is to anesthetize a sensory nerve that supplies innervation to the area of injury at a single more proximal site. The advantages of this technique over a field block are that it is usually much faster, it requires a smaller volume of local anesthetic, and it avoids distortion of the surgical site, as well the bleeding that often ensues after multiple needle sticks. It does, however, require a thorough knowledge of the anatomy of the nerve, and it does not always provide complete anesthesia to the desired site secondary to collateral innervation.

This chapter will focus on regional nerve blocks in two key anatomic regions: the face and hands.

Choice of Anesthetic Agent

The previous chapter discussed the various anesthetic agents in detail. Briefly, most blocks can be achieved using 1% lidocaine with epinephrine (1:100,000). The addition of epinephrine prolongs the duration of action of the anesthetic, as well as providing vasoconstriction of the site. Epinephrine can be used anywhere in the face; however it should not be used in the fingers or penis. The addition of bupivicaine to the lidocaine solution can prolong the duration of anesthesia for several hours, providing additional post-procedure pain relief. Furthermore, sodium bicarbonate can be added to the lidocaine solution to cut back on the burning sensation from the injection.

Choice of Syringe and Needle

A 5 ml syringe is usually sufficient for most blocks since rarely is more than this amount required. The smaller syringe is also easier to maneuver. The needle should be a 25 or 27 gauge. The length of the needle must be sufficient to reach the target. For example, the infraorbital foramen is usually reached through the oral cavity, requiring at least a 1 inch needle.

Regional Block of the Scalp

Indication

Anesthesia of the scalp down to the periosteum.

Technique

The scalp is innervated by branches of the trigeminal and cervical nerves. These nerves can be anesthetized as they penetrate the scalp. They become subfascial along

a line that encircles the head (like a skull-cap). This line passes just above the tragus and through the glabella and occiput. A wheal should be raised in the subdermal plane along this line. About 10 ml of lidocaine is required every few centimeters.

Supraorbital Nerve Block

Indication

Anesthesia of the upper eyelid and medial forehead.

Technique

Palpate the supraorbital notch/foramen at the junction of the medial and middle thirds of the orbital ridge (about 2.5 cm off the midline of the face). Raise a wheal using a 25 gauge 1 inch needle. Advance the needle until the tip meets the foramen, and inject 1-2 ml while withdrawing.

Infraorbital Nerve Block

Indication

Anesthesia of the lower eyelid, medial cheek region or upper lip.

Extraoral Technique

Place the index finger in the canine fossa pointing caudal towards the infraorbital foramen. Raise a wheal using a 25 gauge 1 inch needle about 1 cm lateral to the ala of the nose. Advance the needle towards the tip of the finger until the tip meets the foramen on the maxilla. Inject 1-2 ml into the foramen and while withdrawing. The infraorbital canal runs in a superolateral direction.

Intraoral Technique

Retract the cheek with the thumb and introduce the needle into the upper gingival sulcus above the second bicuspid. Rest the syringe on the lower lip of the patient. Aim slightly laterally away from the midline along the maxilla until the infraorbital foramen is encountered. Inject 1-2 ml into the foramen and inject while withdrawing. The infraorbital canal runs in a superolateral direction.

Mental Nerve Block

Indications

Anesthesia of the lower lip, anterior portion of the lower jaw (including the anterior lower teeth).

Extraoral Technique

The mental foramen is located directly below the root of the second lower bicuspid at the midpoint between the lower and upper margins of the mandible. The needle is inserted into the skin and a wheal is raised. It is aimed inferolaterally towards the mental foramen, and anesthetic is injected while the needle advances until bone is met. After instilling 1 ml of anesthetic, the needle is used to palpate the mental foramen after which an additional 1 ml is injected into the foramen.

Intraoral Technique

With the mouth closed, the cheek is retracted and needle inserted into the gingivobuccal sulcus below the bicuspids. A wheal is raised, and the needle is aimed towards the root of the second bicuspid and advanced at 45˚ until bone is reached. After instilling 1 ml of anesthetic, the needle is used to palpate the mental foramen after which an additional 1 ml is injected into the foramen.

Regional Block of the External Nose

Indications

Anesthesia of the skin of the nose.

Technique

The two sides of the nose should be anesthetized separately. The needle is introduced into the skin about 1 cm lateral to the alar base. A wheal is raised, and the needle is advanced towards the radix; 2-3 ml is injected along this line. The needle is withdrawn almost completely and then directed downward towards the oral commissure. An additional 1-2 ml is injected along this course. The entire procedure is repeated for the other side of the nose.

Regional Block of the External Ear

Indication

Anesthesia of the ear.

Technique

The anterior ear is supplied by the auriculotemporal nerve and the posterior ear by the greater auricular nerve and occipital nerve (including its mastoid branch). These nerves all reach the ear from the superior, posterior and inferior directions only. A needle is inserted 2 cm above the helix and advanced anteroinferiorily and posteroinferiorily. The needle is removed and inserted 3 cm posterior to the ear and advanced anterosuperiorily and anteroinferiorily. The needle is removed and inserted 1 cm below the ear, advancing it posterosuperiorily and anterosuperiorly. When these three injections are completed, a continuous infiltration around the entire ear (excluding the anterior portion) has been achieved.

Radial Nerve Block

Indication

Anesthesia of the radial dorsum of the hand and proximal thumb, index and middle finger. The ring finger should also be blocked with an ulnar nerve block.

Technique

Identify extensor pollicus longus (dorsal tendon of the anatomical snuffbox).
Insert the needle over the tendon at the base of the first metacarpal.
Inject superficial to the tendon (about 2 ml) and over the snuffbox (1 ml).

Median Nerve Block

Indication

Anesthesia of the palmar side of the thumb index finger and middle finger, and radial side of the ring finger. Also, the nailbeds of the above fingers can be blocked with this technique. The thenar region (palmar cutaneous branch of the median nerve) can also be blocked.

Technique

Identify flexor carpi radialis and palmaris longus by having the patient make a clenched fist and slight wrist flexion.
Insert the needle 2 cm proximal to the proximal wrist crease.
As the needle passes through the flexor retinaculum, 3 ml of anesthetic is injected.
Injection of an additional 1 ml above the retinaculum will anesthetize the palmar cutaneous branch supplying the thenar eminence.

Ulnar Nerve Block

Indications

Anesthesia of the little finger and ulnar side of the ring finger.

Technique

Identify flexor carpi ulnaris by having the patient forcefully ulnar deviate the wrist slightly with the fingers fully extended.
The ulnar nerve lies radial to the flexor carpi ulnaris tendon.
Insert the needle 2 cm proximal to the wrist on the radial side of the tendon directed towards the midline.
After parasthesias are felt, inject 4 ml of anesthetic in a fanwise fashion along the course of the nerve.

Digital Nerve (Ring) Block

Indications

Anesthesia of the digit.

Technique

With the dorsum of the hand facing upward, insert the needle into the dorsal skin at the midpoint between the digits (the apex of the “V” of the web space) and raise a wheal.
Advance the needle towards the palm perpendicular to the skin and infiltrate along this course about 2 ml of anesthetic.
Withdraw the needle almost completely and then begin advancing the needle towards the middle of the digit, infiltrating the skin on the dorsum of the finger base.
The digital nerves on either side of the finger should be anesthetized in this manner.

Pearls and Pitfalls

The supraorbital, infraorbital and mental foramena all lay along a vertical line that also includes the pupil in the midgaze position. Therefore, if any two of the foramena have been located, the third can be easily found.
Epinephrine requires about 10 minutes until full effect, and the same is true for lidocaine used in a regional block. Therefore, one should administer the block in advance.
Several studies reviewing thousands of cases of digital anesthesia have found that using epinephrine in the digits is entirely safe, with almost no cases of digital ischemia secondary to the epinephrine. However, until a prospective trial demonstrates the absolute safety of this practice, epinephrine should not be used in the digits.
An adequate block is not always 100% successful at eliminating pain from the site of injury. Often a supplemental field block is required after the initial regional block has taken effect.

Local Anesthetics

2008-08-16T02:43:00.000-07:00

Introduction

As the number of plastic surgical procedures performed under local anesthesia continues to grow, a thorough understanding of local anesthetic techniques has become essential. Furthermore, emergency care of lacerations, avulsions and other acute injuries also necessitates an adequate grasp of local anesthesia. It is important to obtain informed consent prior to using local anesthesia. Discussion of the risks and benefits of the surgery alone is not sufficient. Anesthetic-related issues such as adverse reactions, systemic toxicity, nerve damage, hematoma and pain both during and after the injection should be addressed.

Mechanism of Action

Local anesthetics exert their effect by temporarily blocking nerve conduction. This is achieved by interference with influx of sodium ions through the sodium channel. This leads to a slowing of the rate of membrane depolarization, a lowering of the threshold potential, and the inhibition of propagation of the action potential down the length of the axon. The smallest unmyelinated sensory nerves (C fibers) are affected first. The motor nerves are usually larger and myelinated, and are unaffected or only mildly affected by the actions of local anesthetics at the doses commonly used.

Pharmacodynamics

Local anesthetics can be classified based on their molecular structure as either amides or esters (Table 7.1). The amides, such as lidocaine, are metabolized in the liver by microsomal enzymes and excreted in the urine. The esters, such as cocaine, are quickly metabolized by plasma pseudocholinesterase into PABA and excreted in the urine.

Table 7.1. Commonly used local anesthetic agents and their duration of action

Anesthetic Agent Class Duration of Action

Lidocaine (Xylocaine) Amide 1.5-2 hours

-Lidocaine with epinephrine up to 3 hours Bupivicaine (Marcaine) Amide 3-6 hours

-Bupivicaine with epinephrine up to 10 hours Mepivicaine (Carbocaine) Amide 2.5-3 hours Cocaine (Cocaine) Ester 0.5-3 hours Tetracaine (Pontocaine) Ester 1-3 hours

Local anesthetics are acidic, in the pH range of 5-7 . Their pH further decreases with the addition of epinephrine to the anesthetic solution. Once they enter the tissue, the body’s bicarbonate buffer system converts the acidic solution to a more basic form. This is the active, uncharged form of the drug that can diffuse through the plasma membrane of the neurons. Bupivicaine, with its higher pKa, has a slower onset of action than lidocaine, which has a lower pKa. Acidic tissue, such as a hypoxic or infected wound, increases the fraction of ionized drug, thus delaying the onset and decreasing the efficacy of local anesthetics.

The Addition of Epinephrine

A vasoconstricting agent such as epinephrine, is often added to local anesthetic solutions. This provides the following benefits:

Decreases the rate of systemic absorption
Reduces the risk of systemic side effects
Prolongs the duration of action of the anesthetic
Improved hemostasis due to its vasoconstrictive effects

Premixed solutions containing epinephrine are acidified even further than plain local anesthetics. This increased acidity delays the onset of action and is more painful on injection. There is no utility in using greater than 1:100,000 epinephrine solutions. No additional vasoconstrictive benefit is offered, whereas the risk of toxicity increases in a dose-dependent manner. Adequate hemostasis relies greatly on allowing adequate time for the vasoconstrictive effects to occur. This usually takes 7-10 minutes.

Contraindications to the use of epinephrine-containing solutions include patients with unstable angina, cardiac dysrhythmias, severe uncontrolled hypertension, or pregnant patients with placental insufficiency. Relative contraindications include hyperthyroidism and concurrent use of MAOI or tricyclic antidepressants. When contraindicated, phenylephrine (1:20,000) can be substituted, however it is not as effective as epinephrine.

The Addition of Bicarbonate

Sodium bicarbonate can be added to local anesthetics in order to alkalinize the solution. This neutralization of the low pH creates a solution that is less irritating to the tissues and less painful on administration. The limiting factor in the addition of bicarbonate is the tendency for the lipid soluble agents, such as bupivicaine, to precipitate at the more neutral pH values. Therefore, bicarbonate can be added to lidocaine but should generally not be used with bupivicaine.

Lidocaine

Lidocaine is the most widely used local anesthetic. It is prepared as a 1% (10 mg/ ml) or 2% (20 mg/ml) solution with or without epinephrine. Its duration of action is about 1.5 hours without epinephrine, and this is doubled to 3 hours with the addition of epinephrine to the solution (1:100,000). Lidocaine can also be used as a dilute solution (0.2%–0.5%) for certain procedures such as a rhytidectomy. This solution is adequately anesthetizing and vasoconstrictive. A commonly used dilute solution, the modified Klein solution, can be prepared as follows: 20 ml of 2% lidocaine, 5 ml of sodium bicarbonate, and 1 ml of 1:1,000 epinephrine all mixed in 500 ml of lactated Ringer’s solution. The maximum safe dose for plain lidocaine is reported as 3-4 mg/kg. With the addition of epinephrine, this increases to 7 mg/kg.

Recent literature, however, refutes this figure, providing evidence for a much higher maximal safe dose-up to 35 mg/kg when combined with epinephrine.

Bupivicaine

Bupivicaine is widely used in plastic surgery because of its long duration of action. It is effective for 3-6 hours, significantly longer than lidocaine. The addition of epinephrine can increase this duration to 10 hours. It comes as a 0.25% or 0.5% solution, with or without epinephrine. It is somewhat more painful than lidocaine on administration. It should not be used for large volume infiltration because of its high toxicity profile. It can, however, be combined with lidocaine for lengthy facial procedures such as a rhytidectomy. This combination has a rapid onset of action due to the lidocaine, and a long duration of action due to the bupivicaine. The maximum safe dose of bupivicaine is 2.5 mg/kg, and this increases to 3 mg/kg with the addition of epinephrine.

Mepivicaine

Mepivicaine is similar to lidocaine except for its slightly longer duration of action. Its anesthetic effects can last up to 3 hours. It is prepared as a 0.5% or 1% mixture. It is much less commonly used than lidocaine due to its higher cost and lesser availability. It also has a slightly increased risk of toxicity compared to that of lidocaine.

Eutectic Mixture of Local Anesthetics (EMLA)

EMLA is typically a cream composed of 2.5% lidocaine and 2.5% prilocaine. It provides dense topical anesthesia 45-60 min after application. It must be covered with an occlusive dressing for this period in order for the cream to be effective. Within 2 hours, the maximal depth of penetration is reached. EMLA cream is not widely used because of the long latency until onset of action and the need for the occlusive dressing. It is effective in children who will not tolerate a needle stick, as long as it is applied sufficiently in advance.

Cocaine

Cocaine is used primarily as a topical agent for septo-rhinoplasty procedures. It comes in 4% or 10% solutions. As opposed to other local anesthetics, cocaine produces significant local vasoconstriction without the addition of epinephrine. Its onset is extremely rapid (1-2 minutes), but it takes an additional 5 minutes for its vasoconstrictive effects to begin. Its duration of action is up to 3 hours. Cocaine can be highly toxic by sensitizing the heart to circulating catecholamines. This can lead to tachycardia, hypertension, coronary vasospasm and dysrhythmias. Its CNS effects are stimulatory before leading to confusion, dysphoria and seizures. The maximum safe dose is about 3 mg/kg.

Tetracaine

Tetracaine, similar to cocaine, is used as a topical agent in nasal surgery. It can also be combined with EMLA as a topical agent for anesthesia for closed nasal reduction. It comes as a 0.05% to 4% solution. It has a rapid onset and is effective for 1-3 hours. Tetracaine is several times more potent than cocaine. It is extremely toxic due to its slow rate of metabolism, and the maximum safe dose is 1 mg/kg.

Toxicity

The risk for adverse reactions with local anesthetics is low, but it is important to be familiar with the signs and symptoms of toxicity. Some sites on the body are at greater risk for toxicity due to their robust blood supply. The face and scalp are rich in vascularity, and the systemic absorption of the drug from these sites is higher. In addition, patients with pseudocholinesterase deficiency, myasthenia gravis and those taking cholinesterase inhibitors are at a higher risk for overdose. Certain local anesthetics pose a higher risk of toxicity due to their lipid solubility. For example, bupivicaine is more lipid soluble than lidocaine and has a higher risk of toxicity.

The cardiovascular and CNS are the two systems most commonly affected by local anesthetic toxicity. CNS manifestations occur before cardiac signs, and the early signs and symptoms include restlessness, headache, disorientation, dizziness, blurred vision, tinnitus, slurred speech, nystagmus and twitching. Late signs of toxicity include generalized seizures, apnea and death. Treatment of seizures is by administration of a benzodiazepine such as diazepam or midazolam. Cardiovascular manifestations appear after those in the CNS and include myocardial depression, hypotension or shock, and dysrhythmias such as prolonged P-R interval and widening of the QRS complex. Of the commonly used local anesthetics, bupivicaine is the most cardiotoxic due to its strong affinity for the cardiac calcium channels.

Allergic Reactions

Allergies to local anesthetics are extremely rare, and account for less than one percent of adverse drug reactions during anesthesia. Reactions can range from a subtle rash to a full-blown anaphylactic response. The amides, such as lidocaine, rarely cause allergic reactions. The esters, however, such as cocaine, are metabolized by plasma pseudocholinesterase into PABA, and allergic reactions to these anesthetics are more common. If an allergic reaction does occur following administration of a local anesthetic, the culprit is usually one of the preservatives or additives in the solution rather than the anesthetic agent itself.

Pearls and Pitfalls

It has become increasingly clear that the maximum safe dose of lidocaine is much higher than previously thought. The traditional value of 7 mg/kg as the maximal dose of lidocaine with epinephrine is probably much too low. Recent literature supports a value closer to 35 mg/kg. Furthermore, the common use of dilute solutions of lidocaine with epinephrine has demonstrated that concentrations above 1% are not required. In the vast majority of cases, dilute solutions of lidocaine will provide adequate anesthesia, and the addition of epinephrine will greatly increase the maximal dose that can be safely used, while decreasing blood loss. One should wait at least 7-10 minutes for the vasoconstrictive effects of the epinephrine to take effect.

Leeches

2008-08-16T02:40:00.000-07:00

Leeches have been used for medicinal purposes for 2,500 years. Their contemporary use in plastic surgery, first described in 1836, is for the relief of soft tissue venous congestion, most commonly in compromised flaps and in avulsed or replanted appendages such as the ear and finger. Leeches have proven especially useful in microsurgery, in which venous anastamoses may prove difficult. The success rate of salvaging tissue with medicinal leech therapy has been reported to be up to 70-80%. In 2004, the U.S. Food and Drug Administration approved the commercial marketing of leeches for medicinal purposes.

Medicinal leeches, typically Hirudo medicinalis, are unique in their ability to effect prolonged venous bleeding, because they inject salivary substances that have anticoagulant, antiplatelet and vasodilatory effects. These components cause bleeding for up to 24 hours, long after the leech has been removed. Leeches also release a local anesthetic, rendering bites painless.

The indication for the use of leeches is venous congestion. This diagnosis can be made by observing the following signs: cyanosis, edema and brisk capillary refill. Pricking the affected area with a needle results in dark bleeding. Intraoperative issues, such as difficulty with a venous anastomosis or undue pedicle tension, also suggest the diagnosis. When flaps are congested, other mechanical means to improve venous outflow should be considered first, including removing tight sutures, decompressing tunneled pedicles, and evacuating hematomas.

While the initial leech bite causes about 5-15 ml of blood loss, each wound can ooze an additional 50-150 ml of blood over a period of up to 24 hours. As such, the number and timing of leeches to be applied should be tailored to the area involved. Venous ingrowth can be anticipated in 3-5 days. Treatment should be continued until signs of venous congestion subside. This may take up to 10 days.

Leeches are commercially available from several sources. After receipt, leeches can be stored in the pharmacy or on the patient floor. They must be refrigerated and kept in a feeding medium (either dissolved in distilled water or a gel) that arrives with them.

A general approach is as follows:

Clean the skin thoroughly with soap and water. It is especially important to remove old antiseptic or other noisome substances, as they may affect the leech’s appetite.
Cut a 1 cm hole in the middle of a saline-moistened gauze sponge. Place this sponge so that the hole overlies the area to which the leech is to be applied.
Place the leech on the gauze pad such that its head (the end that tends to move the most) is against the skin. It may be helpful to place the leech in the barrel of a 5 ml syringe (after removing the plunger) and inverting the syringe against the skin so that the leech can be specifically applied.

Leeches will usually attach immediately. If not, prick the skin with a needle before reapplying the leech.
Leeches will typically remain in the same place until they are completely distended, at which point they will fall off. This usually takes 30-45 minutes. Instruct the patient’s nurse to check on the patient often so that leeches are not lost after detachment.
Wounds can be encouraged to bleed after detachment by occasionally scraping the eschar off.
Used leeches can be discarded by anesthetizing and then euthanizing them in 8% and 70% alcohol, respectively. They should be considered biohazardous and disposed of as such. If several leeches are used concurrently, it may be necessary to check the patient’s

hemoglobin/hematocrit at regular intervals. All patients should be started on an oral antibiotic while on leech therapy. Suggested antibiotics include a fluoroquinolone or amoxicillin/clavulanic acid. Patients with HIV or taking immunosuppressive medications should not undergo leech therapy because of the risk of bacterial sepsis.

Pearls and Pitfalls

Leeches should be used as a treatment of last resort when all other means of venous outflow establishment are exhausted. It is imperative to relieve a mechanical or iatrogenic cause of venous compromise.

It is critical to rule out arterial insufficiency as the cause of flap necrosis or pallor, since leeches will not work in this situation.

Flaps demonstrate significantly decreased survival after 3 hours if venous congestion is not relieved. As opposed to arterial ischemia, venous stasis tends to cause irreversible damage. Since leeches must be flown in, it is wise to anticipate their need as early as possible. We have ordered them intraoperatively in some cases.

Although leeches can be reused on the same patient, they tend not to work as well. Used leeches should not be stored with unused ones to prevent cross-contamination. Used leeches should never be applied to another patient.

The importance of an appropriate bedside manner in ensuring acceptance of and compliance with this regimen cannot be understated. Most patients are willing to accept treatment when it is explained in a thorough and confident manner. It is also critical to include nursing and ancillary staff in the discussion of leeches, as many will not have seen them used before. We have found that by observing the first application of a leech, most nurses are willing to apply subsequent leeches without supervision.

Leech Suppliers

Carolina Biological Supply Co.—(800) 262-2922

Leeches U.S.A.—(800) 645-3569, after hours: (800) 488-4400 Ext. #2475

Negative Pressure Wound Therapy

2008-08-16T02:31:00.000-07:00

Introduction

Management of difficult acute and chronic wounds poses a significant challenge to the patient and the caregiver. The application of negative pressure wound therapy (NPWT) has proven to ease some of this burden by promoting a favorable wound-healing environment, decreasing the need for frequent dressing changes, improving patient comfort, and reducing associated costs. In NPWT, a pliable foam dressing is cut to shape, placed into a wound, and covered with an occlusive dressing. Controlled sub-atmospheric pressure is then applied to the wound by evacuating air and liquids from the foam dressing. The most commonly used device for applying NPWT is the wound VAC®.

Mechanism

Initial research on pigs demonstrated the superiority of NPWT when compared with moist saline dressings. Although few randomized controlled trials exist in humans, one review suggests that NPWT improves granulation, augments wound contraction, and reduces the need for systemic antibiotics. Several mechanisms may be responsible for these observations. NPWT has been shown to improve local tissue perfusion and reduce the bacterial load on wounds. NPWT may also improve granulation tissue formation by reducing proteolytic enzymes found in wound exudates, by promoting a moist wound, and by applying shear forces that induce cellular hyperplasia.

Indications

Since NPWT has become commercially available, the list of indications has continued to grow (Table 5.1). NPWT is indicated for almost any open wound where surgical closure is not feasible or desirable. While it may be used as a sole treatment toward achieving wound closure, NPWT is often used as a bridge toward definitive surgical management. Much of its utility is in creating favorable conditions for subsequent wound reconstruction.

With the success seen in treating a variety of wounds, many authors have tried to extend the application to improve graft take and flap survival. When flaps are used to cover wounds, some studies suggest that additional use of the NPWT may promote improved flap survival and overall wound healing. In several case series, skin graft take was shown to be 90% or greater when the VAC was employed in lieu of a traditional bolster dressing. Recipient sites with irregular contours, susceptibility to shear forces, and excess drainage were thought to be particularly amenable to VAC dressings. Nevertheless, these results have yet to be confirmed in randomized control trials.

Table 5.1. Indications and contraindications for use of NPWT
	Indication							Notes
	Chronic open wounds
	Diabetic ulcer
	Pressure sore							Debridement must be performed prior to application
								of NPWT
	Traumatic wounds
	Extirpative defects							Brachytherapy and external-beam irradiation can be
								performed through the dressing
	Spinal and orthopedic							Dressing can be placed directly over hardware
	wounds							after debridement has been performed
	Sternotomy defects
	Open abdomen							Excellent for the temporary management of bowel
								edema and gross peritoneal contamination
	Burns							May be applied over allograft of skin substitute
	Skin graft bolster							NPWT improves graft take by limiting shear forces
								and evacuating fluid collections

Contraindications
Malignancy in the wound

Untreated underlying osteomyelitis Nonenteric or unexplored fistulas Undebrided necrotic tissue Untreated active soft tissue infection Exposed internal organs Exposed blood vessels or vascular prosthetic grafts Coagulopathic patients (relative)
Technique

Application of NPWT can be performed by anyone with the appropriate training, provided that the wound is hospitable. Prior to application, the wound should be debrided of any necrotic or fibrinous debris and adequate hemostasis achieved. The surrounding skin is then cleansed and dried. The sponge is cut to be slightly smaller than the volume of the wound. The adhesive dressing is then applied over the sponge such that there is at least a 6 cm overlap on adjacent skin; it is imperative that a hermetic seal be achieved. Once the adhesive dressing has been applied, it is pierced and the adhesive suction tube is applied over this opening. The device is then turned on and continuous suction is applied. When placed properly, the dressing will create a closed suction environment. Depending on the nature of the wound, the NPWT dressing can be changed every 48 to 72 hours. The dressing should be taken down sooner should the patient show signs of infection or if the seal on the dressing becomes compromised.

The VAC® device comes with two types of foam available for use. The original foam is black, and it is made of polyurethane. It is hydrophobic which enhances exudate removal. It has reticulated pores and is considered to be the most effective at stimulating granulation tissue while aiding in wound contraction. The second, newer available foam is white. It is a denser foam with a higher tensile strength. It is hydrophilic and possesses overall nonadherent properties. The white foam does not require the use of a nonadherent layer. It is generally recommended for situations in which slower growth of granulation tissue into the foam is desired or when the patient cannot tolerate the black foam due to pain. Due to the fact that it has a higher density than the black foam, higher pressures must be utilized in order to provide adequate negative pressure distribution throughout the wound. Newer foams are constantly emerging, such as silver-impregnated foams.

Pearls and Pitfalls

Though the NPWT dressing is applied less frequently than the comparable saline dressings, some patients find it painful and require appropriate premedication with analgesics.
The skin surrounding the wound should be completely dry prior to placement of the adhesive. Shaving of hair and application of Benzoin^TM may facilitate adhesion.
The foam should be cut down to the proper size so that it fits within the borders of the wound, otherwise it will compress the surrounding healthy skin.
After placing the dressing and applying the vacuum, ensure an adequate seal by clamping the tubing leading to the dressing and then disconnecting the tubing from the machine. If the seal is adequate, the sponge should slowly return to its original shape.
If poor hemostasis is presumed or if the wound is particularly “weepy”, close monitoring of the patient’s hemodynamic and fluid status is warranted.
The foam should not encroach on normal surrounding skin. However, two separate wounds can be hooked up to a single suction tubing by bridging the two sponges with a thin piece of foam that traverses the normal interfering skin.
A useful trick for dressing change analgesia is to clamp the tubing and inject 1% lidocaine with epinephrine (10-30 ml) into the tubing distal to the clamp. The vacuum will suck the local anesthetic into the wound.

Pharmacologic Wound Care

2008-08-16T02:29:00.000-07:00

Patient Assessment

As the wound healing process has been better elucidated, the practice of wound care has evolved. However, the basic principles of good wound care have not changed significantly over time. The process begins with an assessment of the entire patient. Any underlying medical conditions that impair wound healing must be treated. These include systemic infection, hyperglycemia, inadequate nutritional status, poor circulation, a deficient immune system, and the absence of someone dedicated to caring for the wound. Once patient factors have been adequately addressed, attention should be turned to the wound itself.

The majority of chronic wounds encountered in hospitalized patients can be categorized into four types of ulcers: pressure, diabetic, venous and ischemic. In addition, chronically infected wounds can occur in the setting of underlying osteomyelitis or a foreign body (such as orthopedic hardware). With respect to local wound care, the principles are always the same: eradicate infection, debride necrotic tissue, remove any nonessential foreign material, maximize arterial inflow and venous outflow, and keep the wound moist and clean.

Topical pharmacologic wound care can help achieve these goals to a certain extent. In broad terms, agents commonly used in local wound care can be grouped into three categories: antimicrobial agents, enzymatic agents and growth factors.

Antimicrobial Agents

Topical antimicrobials are moderately effective in treating infected wounds. They provide the benefit of delivering a high therapeutic dose of the drug to a local area with minimal systemic side effects, particularly in wounds with relatively underperfused tissues. They are not, however, a substitute for systemic antimicrobial therapy when indicated (e.g., surrounding cellulites of the wound). The goal of topical antimicrobial therapy is to diminish the burden of bacteria to a level that is manageable by the host immune cells. In fact, sub-infection levels of bacteria have been shown to accelerate wound healing and granulation by promoting the infiltration of neutrophils, monocytes and increased collagen deposition.

There are a variety of commercially available topical antimicrobials (Table 4.1). Silver sulfadiazine (Silvadene®) is used in superficial soft tissue infections. Its effectiveness against Pseudomonas makes it a favored choice in burn treatment. Two other commonly used antibiotic agents are Bacitracin® and Neosporin®. These petroleum-based ointments are useful more for superficial infections. In addition, they can be used on surgical incisions, particularly of the face, to minimize bacterial load and provide a moist wound environment to promote epithelialization.

The role of povidone-iodine (Betadine®) in topical wound care is somewhat controversial. Several animal studies demonstrate no adverse affect on wound tensile strength or reepithelialization rates. On the other hand, several human in vitro and in vivo studies have shown that Betadine inhibits fibroblast proliferation, kerotinocyte growth and migration, and hampers the phagocytic effect of monocytes and granulocytes. In addition, any admixture of blood, pus or fat has been proven to diminish the antimicrobial effect of Betadine. Given this data, many plastic surgeons do not use Betadine as a topical antimicrobial, although it is still commonly used in the operating room as a prepping agent. Other specialties that treat wounds still use Betadine due to the lack of convincing clinical trials and a long history of its use.

Enzymatic Agents

In addition to appropriate antimicrobial therapy, the wound must be properly debrided of any devitalized tissue. Necrotic tissue can serve as a culture medium for further bacterial proliferation, and its presence will impede the healing process. Sharp debridement is the simplest, most effective means of eliminating nonviable tissue. Enzymatic debriding agents are an adjunct to surgical debridement. As with antimicrobial agents, there is a spectrum of enzymatic agents that is commercially available (Table 4.2).

Growth Factors

Perhaps the realm with the greatest therapeutic potential in the pharmacologic treatment of wounds is the use of growth factors. A variety of growth factors and chemotactic agents have been discovered since the 1970s, and many have been probed for possible clinical applications. Platelet-derived growth factor (PDGF) is present in acute surgical wounds, however not in chronic, nonhealing wounds. In several randomized controlled trials, topical application of PDGF increased wound tensile strength and accelerated the healing process overall. Recombinant PDGF is currently the only cytokine approved for use in chronic wounds, specifically in neuropathic diabetic foot ulcers. It is available commercially as beclapermin (Regranex®); however the extremely high cost makes its use prohibitive in many centers.

Pearls and Pitfalls

Choosing a topical wound care agent must be done in conjunction with choosing the appropriate dressing.
If the wound is complicated by underlying osteomyelitis, topical antibiotics will not suffice in eradicating the infection.
Close observation is warranted when instituting a new therapy for the wound since many of these agents have side effects and can even induce an allergic reaction.
Enzymatic agents cannot penetrate thick eschar. Necrotic tissue should be sharply debrided before applying a topical enzymatic substance.
Some topical wound care agents, such as papain-containing enzymatic agents, are painful when they come in contact with surrounding healthy skin.

Dressings

2008-08-16T02:25:00.000-07:00

Introduction

A surgeon’s goal to achieve successful wound healing rests on two basic principles: (1) optimizing conditions for the body’s natural wound healing mechanisms to occur, and (2) minimizing the manifold detriments which interfere with this process. A few, if any methods currently exist to actually enhance wound healing, the classic tenets of “keep the wound moist, clean, free of edema and free of bacteria” are based on these two fundamentals, which in turn are rooted in basic principles of wound healing biology. Although wound healing products available today are increasingly varied and sophisticated, their primary function remains to support the intrinsic wound healing process.

Wound Healing

Wound healing occurs as an orchestrated series of four overlapping phases: coagulation (immediate), inflammation (0-7 days), proliferation (4-21 days) and remodeling (14 days-2 years). Actual physical closure of the wound occurs during the proliferative phase by granulation (fibroblasts, endothelial cells), contraction (myofibroblasts) and epithelialization (keratinocytes). An uncompromised wound will progress normally through these phases, however a compromised wound can arrest in the inflammatory or proliferative phases; resulting in delayed wound healing. If a wound is able to overcome its compromising factors and reach the remodeling phase within one month, it is termed an acute wound. If a wound is overwhelmed by its compromising factors and fails to heal within three months it is called a chronic wound.

Table 3.1 lists the factors that impair wound healing. They can be classified as intrinsic (underlying conditions that inhibit normal wound healing), extrinsic (external factors imposed on the body that inhibit wound healing) and local (factors which influence the condition of the wound bed). These impediments must be eliminated or limited in order to optimize wound healing.

Goals of Wound Dressings

The purpose of wound dressings is to control the local factors and create an environment that will optimize the wound bed for healing. The ideal dressing would achieve this goal by having the following properties:

Maintain a moist wound healing environment
Absorb exudate
Provide a barrier against bacteria
Debride—both macroscopic and microscopic material

Table 3.1. Factors that impair wound healing
Intrinsic	Extrinsic		Local
Wound:	-Smoking		-Desiccation
-Hypoperfusion	-Radiation		-Inflammation
-Hypoxia	-Chemotherapy		Infection
-Drugs (e.g. steroids)			Bacterial burden
Systemic:		-Temperature (cold)	Hematoma
-Age		-Mechanical	Foreign Body
-Obesity		-Pressure	Ischemia
-Malnutrition		-Sheer	-Necrotic burden
-Hormones		-Trauma	Dead cells, exudate
-Disease (e.g., diabetes,			-Cellular burden
cancer, uremia, EtOH)			Senescent and
-Venous insufficiency			nonviable cells
-Extremity edema (e.g., CHF)			-Edema
-Arterial insufficiency/PVD

Reduce edema
Eliminate dead space
Protect against further injury from trauma, pressure and sheer
Keep the wound warm
Promote skin integrity of the surrounding tissue and to do no harm to the wound

Types of Dressings

There are hundreds of commercially available wound dressings. It is beyond the scope of this chapter to cover all of them. A practical approach is to classify dressings by the material of which they are composed. The commonly used dressings are summarized in Table 3.2.

Gauze

Gauze is composed of natural or synthetic materials and may be woven (lower absorptive capacity, higher tendency to adhere to the wound bed, and high amount of lint) or nonwoven (superior absorbency, less adherence, low lint). This dressing is commonly used to cover fresh postoperative incisions. Other popular uses of gauze have remained the wet-to-dry (WTD) dressing and wet-to-moist (WTM) dressings. WTD dressings should be avoided as a method for mechanical microdebridement, since this debridement is nonselective and will harm viable tissue during dressing removal. As WTD dressings dry out, they also lead to wound desiccation, violating one of the central wound healing principles. WTM dressings—used to maintain a moist environment—are also less than ideal because they are labor intensive requiring many dressing changes, and in the process tend to dry out anyway, achieving the opposite of their intended purpose.

Other uses of gauze exist. It is indicated for wounds with exudate so heavy that other more sophisticated dressing types would not be cost-effective. Examples include drainage from a seroma or a fistula requiring many daily dressing changes. Gauze is also indicated as a primary dressing over ointments and as a secondary dressing over wound fillers and hydrogels.

Transparent Films

Films are composed of a thin, clear polyurethane with an adhesive side which sticks only to dry, intact skin and not moist wound bed. They are designed to regulate the correct amount of moisture beneath the dressing and are water vapor and gas permeable, yet impermeable to bacteria and liquids. These dressings are indicated for partial-thickness or superficial wounds with minimal exudates (e.g., split-thickness skin graft donor site). They are also ideal for primarily-closed, nondraining surgical wounds. Films may also be used as secondary dressings over absorptive fillers on full-thickness wounds. Because they are impermeable to liquids, they are contraindicated for infected wounds and heavily exudative wounds. Bacteria will be retained rather than debrided, and collection of fluid can lead to maceration of the wound and the surrounding healthy skin.

The moisture regulation of transparent films provides an ideal environment for softening eschar through autolytic debridement. Hydrogels can even be added under the film to speed up this process. Use of films reduces pain and provides protection from friction and sheer forces. Transparency of the films also facilitates easy observation and postoperative monitoring of the wound. When applying films, at least 1 inch of surrounding skin should be utilized for good adherence, which can be aided by use of Benzoin^TM tincture or Mastasol^TM. Films can be left in place for several days, but must be changed earlier if exudate leaks onto intact skin.

Examples of transparent films are Tegaderm^TM and Op-site^TM.

Nonadherent Dressings

These dressings can be nonimpregnated (nylon or polyurethane) or impregnated (gauze with petrolatum or an antibacterial compound). Their purpose is to provide an interface which will not stick to the wound bed and maintain some degree of moisture in the wound bed. Indications for nonadherent dressings are skin grafts and donor sites with minimal to moderate exudate, and abrasions or lacerations. Contraindications are heavily exudative wounds.

Examples include Xeroform^TM, Adaptec^TM and Vaseline-impregnated gauze.

Hydrogels

Hydrogels are composed of 80-99% water suspended in a cross-linked polymer, and are available in amorphous (dispensed from a tube) and sheet forms. Hydrogels preserve wound hydration and actually donate water to the wound, but are not at all absorptive of exudate. They are thus indicated for dry to minimally exudative wounds, such as shallow pressure ulcers, abrasions and other partial-thickness wounds, skin graft donor sites and superficial partial-thickness burns. Sheet gels should be used on superficial wounds <5>

The moisture provided by gels promotes autolytic debridement, however overuse of hydrogels will cause wound maceration. Sheet hydrogels can be changed every 4-7 days and amorphous gels added as needed to titrate wound hydration. Either gauze or a transparent film is used as secondary dressing depending on the tendency of the wound to dry out.

Examples of hydrogels are Curasol^TM, Aquaphor^TM and Elastogel^TM.

Hydrocolloids

Hydrocolloids are composed of hydrophilic colloidal particles (such as gelatin or cellulose) within an adhesive mass (polysobutylene). They come as adhesive wafer dressings designed to interact with the wound bed by forming a gel over it as exudate is absorbed by the dressing, thus forming a protective layer over the wound and creating a moist wound healing environment. The absorptive layer of the dressing is covered by a completely impermeable film.

Hydrocolloids are indicated for wounds with low to moderate exudate, partial- or full-thickness wounds, and granulating or necrotic wounds. A frequent use of these dressings is for venous stasis ulcers. Hydrocolloids may be also used over absorptive wound fillers. They should not be used on infected wounds, heavily exudative wounds or on wounds with fragile surrounding skin. In addition to offering protection from sheer force, these dressings protect against exogenous bacterial contamination, and are relatively painless. They are ideal at providing an environment for autolytic debridement of fibrinous slough. When applied, at least one inch of surrounding skin should be covered to ensure adherence. These dressings should be changed when exudate is within an inch of the dressing edge, which may be daily until exudate slows down, at which time hydrocolloids can be left on for up to seven days.

Examples of hydrocolloids are DuoDERM^TM and Cutinova Hydro^TM.

Foams

Foams are composed most commonly of polyurethane polymers whose primary function is to absorb wound exudate. They come in thin and thick foams, adhesive and nonadhesive foams, foams used to pack wounds and sheet foams. Foams are indicated for wounds with moderate to high exudate, partial- or full-thickness wounds, and granulating or necrotic wounds. They can be used on infected wounds if changed daily, and they can be used over creams or ointments. Foams are not recommended for dry wounds. Foams protect wounds well (although do not reduce force on pressure ulcers), facilitate autolytic debridement, and minimize granulation tissue. As with other dressings, at least one inch of surrounding skin should be covered, and foams can be left on the wound surface for up to seven days.

Examples of foams are Lyofoam^TM and Allevyn^TM.

Alginates

Alginates are composed of naturally occurring mannuronic or glucuronic acid polymers from brown seaweed. They come available as pastes, granules, powders, pads or ropes which soften, gel and conform to the wound, thereby functioning to absorb, exudate and fill dead space. These dressings are indicated for wounds with moderate to high exudate, and may be used on partial- or full-thickness, and granulating or necrotic wounds. They may also be used on infected wounds if changed daily. Foams are well-suited to be used under other dressings such as hydrocolloids to increase dressing wear time. Sheets are generally used on shallow wounds, and ropes, pastes and strands are used to fill deep wounds. Alginates should not be used on minimally exudative wounds because they will adhere to the wound and cause damage when removed. They should not be packed into very deep or tunneling wounds as they may easily be left behind and become a nidus for infection (iodoform gauze^TM is the only appropriate packing for this type of wound).

When applied, alginates should only fill one-third to one-half of the wound since they will expand with time. They require a secondary dressing based on the tendency of the wound to dry out, for example gauze coverage for a highly exudative wound. Alginates should be changed when exudate reaches the secondary dressing.

Examples of alginates are Sorbsan^TM and Carrasorb^TM.

Pearls and Pitfalls

Prior to selection and application of wound dressings, there are several key components to wound management that must be addressed:

One must establish the etiology of the wound and address its causative factors (see Table 3.1).
A clean, viable and well-vascularized wound is the goal. If a wound contains any more than a minimal amount of devitalized (shades of white, brown or black) or infected tissue, dressing changes alone will not be enough to achieve adequate debridement. Surgical debridement and revascularization may be required. A form of debriding dressing can then be used. The choice of dressing material in clinical practice is often arbitrary and based

on the clinician’s personal experience. Many different dressings can achieve the same goal. The key to optimizing wound healing to adhere to these basic principles:

Perform dressing changes with sufficient frequency so that the dressing provides a moist wound environment, but not an overly saturated one.
If the wound is pink, healthy and free of infection, it requires only constant moisture.
Wounds must heal from the inside without the overlying skin sealing over unhealed deeper tissue. Therefore, all dead space must be eliminated by packing the wound. If packing a wound requires more than a single 4x4 gauze dressing, a Kerlix^TM role should be used instead to eliminate the risk of a 4x4 gauze being retained.
Given that the pre-dressing conditions above are met, almost all wounds can be treated using only saline gauze or hydrogel and gauze.
Most importantly, frequent wound monitoring by the clinician is paramount— an ignored wound will not just “go away.” Evaluation of a therapy’s effectiveness is required. Failure of a wound to progress indicates that the patient’s medical condition, the wound environment or the choice of wound dressing must be revisited.

Basic Concepts in Wound Repair

2008-08-16T02:10:00.002-07:00

Definitions

Primary closure is defined as the surgical closure of a wound in one or more layers, within hours of its occurrence. Most surgical incisions and traumatic lacerations are closed primarily.
Delayed primary closure is the surgical closure of a wound, days to weeks later. The granulation tissue is excised, the edges of the wound are freshened and the wound is closed. An example of this technique is the closure of a fasciotomy incision.
Skin grafting is indicated when a defect is too large to close primarily, and creation of flaps is not desirable or feasible. It can be performed immediately following the injury or in a delayed manner. The indications and principles of skin grafting are discussed elsewhere in this book.
Surgical flaps allow the recruitment of local or distant tissue for wound coverage. They are discussed in detail in an upcoming chapter.
Healing by secondary intention is the choice a surgeon is left with when a wound cannot be surgically repaired. This doesn’t mean that the surgeon can leave the wound to heal on its own; daily care and a long-term commitment by the patient and the care-givers are required. The wound must be kept clean and bacterial colonization should be minimized by daily washing, debridement of necrotic tissue and antibiotics when indicated. Healing by secondary intention involves the wound’s progression through granulation tissue formation, epithelialization and contraction.

Suturing Techniques

The commonly used suturing techniques are illustrated in Figure 2.1 and described below. Some important points are applicable to all the techniques. The tissue should be entered as close to 90° as possible. The path of the needle should follow its curve. The suture should be pulled forward through the tissue as gently as possible. These steps will help minimize trauma to the tissues.

Simple interrupted sutures are used to achieve optimal wound edge alignment. This technique is quick and easy to master. It is ideal for most traumatic lacerations. Nylon sutures are commonly used. Knots should never be tied tightly since the tissue can swell and undergo pressure necrosis under the suture.

Continuous running (over and over) closure is the most rapid suturing technique; however it is difficult to achieve precise edge alignment when tension is present. In tension-free regions it can be used with a good cosmetic result. It is useful for achieving hemostasis (e.g., in scalp lacerations). If additional hemostasis is required, the stitch can be locked.
Vertical and horizontal mattress sutures provide good wound edge eversion. They are an excellent choice for use in the hands and feet, or in areas of high skin tension.
Half-buried mattress sutures are useful for closing V-shaped wounds. The mattress portion is horizontal, and the buried portion is placed in the dermis of the tip in order to prevent necrosis of the tip of the V.

Subcuticular sutures are running, intradermal sutures that can provide an excellent cosmetic result by eliminating any surface sutures and the potential epithelial tracking that can result in a permanent suture mark. PDS or other absorbable sutures with low reactivity can be used if suture removal is problematic, such as in young children. If suture removal is an option, Prolene is a good choice since it has minimal tissue reactivity and should be left in place for 2-4 weeks.

Buried, deep dermal sutures are used to decrease skin-edge tension and to allow the superficial closure to be done as tension-free as possible. Generally, absorbable sutures such as Vicryl are used in an interrupted manner to close the deep dermis.

Staples are useful for closing wounds in a variety of situations, such as lacerations or incisions of the scalp. The main advantage that staples offer is that they provide the quickest method of incision closure, and they produce minimal tissue reactivity if removed within a week. However, if left in place too long, staples will produce a characteristic “railroad-track appearance” due to migration of epithelial cells down the tract created by the staples. In addition, precise wound edge alignment is difficult to achieve with staples. Therefore, staples should not be used on visible sites such as the face and neck. They are appropriate for use in reconstructive cases in which precise wound closure is of lesser importance. They can be removed as early as 7 days in straightforward, tension-free closures, or they can be left in place for several weeks if suboptimal wound healing is expected.

Choice of Suture Material

A number of factors should be taken into consideration when choosing suture material:

Absorbable or nonabsorbable. An absorbable suture will lose at least half its tensile strength by 60 days. This half-life can range from 7 days for catgut to 4 weeks for PDS. The absorption of plain and chromic catgut is very unpredictable. Synthetic, absorbable sutures have a more predictable absorption length, ranging from 80 days for Vicryl to 180 days for PDS. With few exceptions, sutures should not be left in the skin permanently unless they are absorbable. Table 2.1 summarizes some of the commonly used sutures and their characteristics.

Tensile strength. The strength of a suture is determined by the material of which it is comprised and by its diameter. Among the nonabsorbable sutures, polyester sutures are the strongest, followed by nylon, polypropylene and silk. For absorbable sutures, the order is polyglycolic acid, polyglactin and catgut. Suture diameter is indicated by the USP rating which gives a number followed by a “zero,” with the higher number indicating a thinner suture. Although a larger diameter suture is stronger, it will also cause greater tissue reactivity and leave a more noticeable scar. Therefore, the thinnest suture that is of adequate strength should be used.

Mono- or multifilament. Monofilament sutures, such as Prolene, are smooth and pass easily through tissue. They cause the least tissue reactivity and trauma and are more difficult for bacterial adhesion. The drawback is that they are difficult to handle compared to multifilament sutures such as silk. In addition, knot security, which is proportional to the coefficient of friction of the suture, is usually greater in multifilament sutures, especially those that are braided. The lower the knot security, the more throws are required to create a secure knot.

Needle types. There is no uniform nomenclature that describes the characteristics of the needles. A simplified approach is to classify needles as tapered, cutting or reverse-cutting. Tapered needles minimize trauma to the tissue. They are used to suture tissue that is fragile and can tear easily. Examples include cartilage and bowel wall. Cutting and reverse-cutting needles are typically used in closing dermis, with the latter being more commonly used due to the creation of a tract that is less likely to tear through the skin.
Suture removal. The optimal timing for removal of sutures varies widely from surgeon to surgeon. Sutures that are left in place too long can lead to epithelial tracking down through the skin along the length of the suture. This may result in punctate scars left from the sutures themselves. In cases in which impaired wound healing is expected and cosmesis is of secondary importance, sutures can be left in place for weeks or even months. The following is a guideline for the timing of suture removal:

Eyelids → 3-5 days Face → 5-7 days Breast → 7-10 days Trunk → 7-10 days Hands → 10-14 days Feet → 10-14 days

Considerations in Wound Healing and Scar Formation

Important factors that contribute to a worsened scar outcome include:

Tension on the closure
Infection
Delayed epithelialization
Imprecise alignment of the wound edges
Impaired blood flow to the healing scar
Genetic factors beyond control

By minimizing these factors, an incision will heal more rapidly and the resulting scar will be more cosmetically acceptable.

Tension on the closure should always be minimized. Closure of the deeper dermis with absorbable sutures will help reduce tension. Whenever possible, incisions should be placed in lines of election. These are the natural creases of minimal skin tension corresponding to wrinkle lines. They are also known as relaxed skin tension lines (RSTL). In the face they usually lie perpendicular to the direction of pull of the muscles of facial expression. If the edges of a wound cannot be brought together without undue tension, undermining or creation of a flap is required. Undermining of the wound edges should be performed with extreme care in order to avoid compromising blood supply. Techniques for creating surgical flaps are discussed in detail elsewhere in this book.

Infection is of greatest concern in areas of poor vascularity such as the extremities. The face and scalp, in contrast, rarely become infected due to their robust blood supply. In general, wounds older than 12 hours should not be closed. This rule can often be violated when dealing with uncontaminated facial lacerations. Grossly contaminated wounds, such as human bites, are at high risk of developing an infection and are not usually closed primarily. Devitalized tissue should always be debrided from all wounds since it will become a nidus for infection. Pulse lavage of wounds is probably the single most effective method for decreasing bacterial count. Either normal saline or an antibiotic solution can be used. Systemic antibiotics should be used with care. A single dose of preoperative antibiotics is usually indicated. In routine clean cases, there is little evidence to support the use of antibiotics beyond the first 24 hours postoperatively. A patient who presents to the emergency department with a wound requiring surgical repair should probably receive a dose of intravenous antibiotics and his tetanus status should be determined.

Delayed epithelialization has been shown in many studies to delay overall wound healing and to worsen scar outcome. The presence of a foreign body will interfere with epithelialization; therefore all wounds should be explored carefully prior to closure. Infection will also delay epithelial migration. Finally, there is mounting evidence that moist wounds epithelialize faster and heal better. A moist healing environment is achieved by occlusion of the incision with a semi-permeable, occlusive dressing such as a Steri-strip®. Such a dressing should be used for the first week postoperatively. Under optimal circumstances, an incision will epithelialize within the first 24 hours.

Improper wound edge alignment occurs during primary closure. It can be minimized by ensuring that the suture traverses the dermis on each side of the incision at the same depth. Once the wound is completely closed, the edges should appear tightly apposed and maximally everted. In irregular wounds, such as stellate-shaped lacerations, one must take care to properly match the two sides. Initial closure of the apex of the laceration can help the pieces properly fall into place.

• Impaired blood flow will prevent the wound from receiving adequate oxygen, nutrients, growth factors and the essential cells involved in the wound healing and scarring process. Little can be done to improve blood flow during primary closure; however a number of factors will worsen it. Smoking has been shown to worsen ischemia in healing wounds by vasoconstriction. External pressure on the wound greater than capillary perfusion pressure (>35 mm Hg) must be avoided. Care should be taken whenever placing circumferential bandages, compression dressings or casts. In addition, sutures that are placed too close to one another can also create areas of ischemia. Other factors that have an unclear effect on scarring, but will impair wound

healing, include elevated blood glucose levels, poor nutritional status, venous and lymphatic insufficiency, chronic corticosteroid use, and a variety of comorbid conditions. Finally, genetics play a definite role in scarring as illustrated by the fact that certain ethnic groups and families have a predisposition to hypertrophic scarring and keloid formation.

The “Dog-Ear”

In certain instances, misaligned closure of a wound can result in a bunching or outpouching of skin termed a “dog-ear.” This will commonly occur when closing oval or circular defects. The “dog-ear” can be excised at its base; however this will result in a scar that is longer than the length of the original defect (Fig. 2.2). In some cases a “dog-ear” will settle with time or can be treated at a later time if it becomes bothersome to the patient.

Z-Plasty

The Z-plasty is a technique that can be used to help prevent scar contracture, or more commonly, as a method of treating scar contracture. Essentially, two interdigitating triangular flaps are transposed resulting in: (1) a change in the orientation of the common limb of the Z; and (2) a lengthening of the common limb of the Z (Fig. 2.3). The change in orientation can be used for managing wounds, in which direct closure may result in undue tension and distortion of nearby structures, such as in the face. The gain in length can be used for treating contracted scars.

Both the length of the transverse limbs and their angle with the common limb can be varied. First, the greater the angle, the greater the amount of lengthening that will occur. A 45° angle will lengthen the common limb up to 50%, and a 60° angle up to 75%. The angles should generally not exceed 60° since excessive transverse shortening and tension will occur. Second, the limb length is determined by how much tissue is available on either side: the more tissue is available, the longer the limbs can be.

Planning the Z-Plasty

When releasing scar contracture, the Z-plasty is created as follows:

The common limb of the Z is drawn along the length of the scar. The parallel, transverse limbs are drawn at 60° to the common limb.
The skin is incised along the Z shape, and any contracted scar is also incised.
Vascularity to the tips of the triangles must be maintained, since they are at the highest risk of necrosis. This is achieved by maintaining a broad base to the triangles, keeping the flaps as thick as possible, avoiding undue transverse tension and handling the tissue with care.
The triangles are transposed, resulting in a reorientation of the transverse limbs

and a lengthening of the common limb. When reorienting the direction of a facial scar, the Z-plasty is created as follows:

The common limb of the Z is drawn along the length of the scar. The new direction of the common limb is planned so that it will lie in a natural skin crease such as the nasolabial fold.
The parallel, transverse limbs should extend from the ends of the common limb up to the skin crease in which the new common limb will lie.
The skin is incised along the lines of the Z and the triangles are transposed. If the blood supply to the tips of the flaps is robust, such as in the face, tip necrosis will not occur and angles more acute than 60° can be used.

Patient Selection

The ideal candidate is one with a pronounced wrinkle pattern. In such individuals, the scar can be reoriented to lie in a pronounced line of election. Children, with their lack of wrinkles are not good candidates for Z-plasties on the face. If the original scar is markedly hypertrophic, the use of a Z-plasty is questionable. Scars that cross a hollow (bridle scars), such as the angle of the jaw, are also amenable to Z-plasty.

Multiple Z-Plasties

A single Z-plasty is limited by the transverse shortening resulting from reorientation of the transverse limbs of the Z. This creates lateral tension that is concentrated most heavily at the apices of each triangle. The use of multiple Z-plasties can provide the same degree of scar lengthening while significantly limiting the amount of transverse shortening. In addition, when a scar is very long and would require enormous transverse limbs, multiple Z-plasties with shorter limbs may be more appropriate. In practice, multiple Z-plasties are usually performed with their common limbs as one continuous unit.

Pearls and Pitfalls

The choice of wound closure technique and suture material vary widely. The goal remains the same: achieving a tension-free closure with clean skin edges that are well approximated. The following questions are useful to address before attempting to repair most types of lacerations, especially in the acute-care setting:

Are there other potential life-threatening injuries that must be dealt with first?
When did the wound occur and what was the mechanism? Is there gross contamination, or is the risk of infection too great to allow primary closure?
Has the patient received prophylactic antibiotics and a tetanus shot (when indicated)?
Has all devitalized tissue been excised and have all foreign bodies been removed?
Can the wound be closed primarily without excess tension? Is there a role for undermining or creation of a flap?
What suture material should be used and which suturing technique should be chosen?
Which points match up in order to recreate the pre-injury anatomy?
Have the wound edges been adequately approximated?
Will the dressing provide adequate occlusion? Is it too tight or will it be too tight if postoperative swelling occurs?
Has the patient received proper postoperative counseling (how to keep the wound clean, when to get it wet, which activities to avoid, when to follow up, and what the signs of a wound infection are)?
When should the sutures be removed?
Long-term: Is the final outcome acceptable? Is scar revision necessary?

Wound Healing and Principles of Wound Care

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Introduction

Wound healing involves a broad range of overlapping cellular and metabolic processes that are orchestrated as a fundamental homeostatic response to injury. An understanding of these concepts is essential to care for wounds in all disciplines of surgery. Plastic surgeons are often consulted by other practitioners to deal with difficult, nonhealing, compromised wounds. Therefore, an understanding of the basic science of wound healing allows one to identify the variables involved in a given wound, and ultimately modulate the process to restore the structure and function of the injured tissue.

Classically, wound healing is divided into three distinct phases: inflammatory, proliferative and remodeling (Table 1.1). Even though each phase is described as a separate event, there is a large degree of temporal overlap and variability in these phases. Factors that influence the timing and length of these events include ischemia, age of the host, nutrition, radiation, smoking, systemic diseases such as diabetes, contamination or infection, desiccation, and the amount of devitalized or necrotic tissue in the wound. This chapter outlines the cellular, vascular and physiologic events underlying wound healing, focusing on the clinically relevant aspects.

Inflammatory Phase

Immediately after injury, bleeding occurs as a result of disruption of the blood vessels. Hemostasis is obtained by initial transient vasoconstriction and subsequent platelet plug and clot formation. Platelet degranulation of alpha and dense granules releases various substances, including platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β), which ignite the chemotaxis and proliferation of inflammatory cells that characterize this phase of wound healing. Following the period of vasoconstriction, the migration of cells to the site of injury is aided by vasodilation and increased endothelial permeability (mediated by histamine, prostacyclin and other substances).

The first cells to arrive are the polymorphonuclear leukocytes (PMNs), which increase in numbers over the first 24 hours. These cells aid in the process of clearing the wound of debris and bacteria. Over the next 2-3 days, macrophages replace the PMNs as the predominant cell type. Macrophages have several critical roles in healing wound, including phagocytosis, release of multiple growth factors and cytokines, and recruitment of additional inflammatory cells. The importance of macrophages is exemplified by studies that have shown that wound healing is significantly impaired without their participation. In contrast, blocking or destroying PMNs during the inflammatory phase still results in a normally healing wound in the absence of bacteria. Finally, lymphocytes populate the wound, although their direct role in wound healing requires further investigation.

Table 1.1. The phases of wound healing

Cellular Vascular Time Phase Response Response Course

Inflammatory PMNs, macrophages, Vasconstriction, followed Injury to lymphocytes by vasodilation 7 days Proliferative Fibroblasts, Angiogenesis, 5 days to endothelium collagen deposition 3 weeks Remodeling Fibroblasts Collagen crosslinking and 3 weeks to increasing tensile strength 1 year

Note: these are overlapping processes and the time course varies depending on local and systemic factors.

Proliferative Phase

The clot formed during the inflammatory phase provides the provisional matrix and scaffolding for the proliferation of the dominant cell type during this phase— the fibroblast. In addition, growth factors stimulate angiogenesis and capillary ingrowth by endothelial cells. The capillaries and fibroblasts form a substrate recognized clinically and histologically as granulation tissue. Fibroblasts produce collagen, which is the principal structural molecule in the final scar. Initially, type III collagen is produced in relative abundance in the healing wound; the normal adult 4:1 ratio of type I to type III collagen is gradually restored during the remodeling phase. The formation of collagen is a multi-step, dynamic process with both intracellular and extracellular components. Procollagen is synthesized and arranges as a triple-helix. After the secretion of procollagen from the intracellular space, peptidases trim residues from the terminal ends, allowing the collagen molecule to associate with other secreted fibrils. Ultimately, hydroxylation and cross-linking of collagen is required for the strength and stability of this protein.

Remodeling Phase

Approximately 2-3 weeks after the initial injury, collagen accumulation reaches a steady-state, where there is no change in total collagen content. During this time, there is replacement of the random collagen fibrils with organized, cross-linked fibrils. This process of remodeling persists for up to a year. Scars continue to gain strength over this phase; however, the tensile strength of scars never reaches that found in unwounded skin, approaching approximately 70% of normal strength.

Epithelialization

The skin is composed of the epidermis and dermis. Among the many important functions of the epidermis is to provide a barrier against bacteria and other pathogens and to maintain an aqueous body environment. When the skin is wounded, epithelialization begins to reconstitute the surface of the wound soon after the initial injury. In partial-thickness wounds, the epithelium derives from dermal appendages, hair follicles and sweat glands. In contrast, in full-thickness wounds, the epithelium migrates from the edges of the wound at a rate of 1 to 2 millimeters per day. A delay of epithelialization leads to a prolonged inflammatory phase, compromising the body’s ability to restore the structure and function of the skin.

Wound Contraction

Myofibroblasts are fibroblasts that contain actin microfilaments, and allow wound contraction to occur. Under certain circumstances, wound contraction is advantageous, because it creates a smaller wound area. However, wound contraction that occurs across a joint, such as the elbow, knee or neck, may create functional limitations.

Pearls and Pitfalls

Understanding the basic science of wound healing has important clinical implications. Hemostasis, adequate debridement of dirty or contaminated wounds, and gentle handling of tissues reduces the inflammatory phase of wound healing. Allowing patients to cleanse their wounds with nonirritating solutions such as water further decreases inflammation. In addition, minimizing tension and dead space during wound closure increases the chance for creating an acceptable scar. Moist wound healing is superior to the healing in a desiccated wound; therefore, dressings should be tailored to create a moist local environment. Finally, an often overlooked facet of wound healing is to optimize nutrition. Patients with chronic or poorly healing wounds often require supplementation to provide the substrates necessary for collagen formation and epithelialization.

Plastic Surgery

Surgical Site Infections

Chronic Wounds

Tissue Expansion

Alloplastic Materials

Microvascular Surgical Technique and Methods of Flap Monitoring

Principles of Surgical Flaps

Principles of Reconstructive Surgery

Surgery under Conscious Sedation

Tumescent Anesthesia

Intravenous Sedation Regimens

Suggested Reading

Basic Anesthetic Blocks

Technique

Indication

Technique

Indication

Extraoral Technique

Intraoral Technique

Indications

Extraoral Technique

Intraoral Technique

Indications

Technique

Indication

Technique

Indication

Technique

Indication

Technique

Indications

Technique

Indications

Technique

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Local Anesthetics

Anesthetic Agent Class Duration of Action

Suggested Reading

Leeches

Suggested Reading

Negative Pressure Wound Therapy

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Pharmacologic Wound Care

Suggested Reading

Dressings

Gauze

Transparent Films

Nonadherent Dressings

Hydrogels

Hydrocolloids

Foams

Alginates

Suggested Reading

Basic Concepts in Wound Repair

The “Dog-Ear”

Z-Plasty

Planning the Z-Plasty

Patient Selection

Multiple Z-Plasties

Suggested Reading

Wound Healing and Principles of Wound Care

Suggested Reading