Chapter 30. Wound Care

The “ABC's” of resuscitation must be addressed before wounds are evaluated. Open wounds are dramatic and often draw the attention of the emergency physician or resuscitation team away from more life-threatening injuries. It is rare that bleeding from even large tissue defects will immediately impact the patient's survival. Secure the airway, ensure adequate ventilation, and stabilize blood pressure prior to assessing wounds.

Hemostasis

Direct Pressure

The simplest and most common method used to achieve hemostasis is direct pressure. A bulky dressing wrapped firmly with an elastic bandage will usually stop venous, capillary, and arteriolar hemorrhage. Most smaller arterial bleeding can be temporarily stopped with this method and larger bleeding vessels may be controlled with digital pressure. Large arteries may ultimately require vascular repair or suture ligation.

Suture Ligation

The decision to ligate an artery should be made cautiously; any uncertainty as to the impact on distal tissue perfusion should prompt consultation of the appropriate surgical specialist. Proximal extremity arterial injuries require emergency vascular surgery consultation.

Simple tying or suture ligation is indicated for most vessels more than 2 mm (1/16 in)in external diameter. To avoid excessive tissue trauma, one must precisely identify and clamp the vessel end prior to ligation. Severed arteries usually require only simple tying. Veins, however, do not hold ligatures well, and suture ligation is preferable. Suture ligation may be performed by passing the suture needle through a portion of the vessel wall and then circumferentially tying the vessel. This method prevents slippage of the ligature. Caution: Do not ligate arteries and veins en masse, because this may predispose to arteriovenous fistula formation. Absorbable sutures are preferred for tying and suture ligation in the acute wound. Synthetic absorbable sutures (polyglycolic acid [Dexon] and polyglactin [Vicryl]) are advantageous because of their low reactivity and high friction coefficients. Chromic catgut is also satisfactory.

Tourniquets

Inflatable cuff tourniquets can be used for temporary hemostasis during wound exploration and repair but are not recommended for periods over 20–40 minutes. Inflate the pressure cuff on the extremity proximal to the wound until hemostasis is achieved. Take particular care to remove tourniquets after 15–20 minutes and before the procedure is completed to check for residual bleeding. A tourniquet inadvertently left in place may cause permanent ischemic damage to the limb.

Epinephrine-Containing Anesthetics

Epinephrine-containing local anesthetic agents such as lidocaine or bupivacaine are commonly used to control bleeding prior to wound repair. This can particularly be useful in highly vascular areas such as the scalp where bleeding can be difficult to control.

Electrocautery

Surgical mono- and bipolar electrocautery units cause hemostasis through thermal coagulation of blood and tissue. The resulting tissue damage lessens the appeal of this technique. Disposable hand-operated electrocautery units are also available.

Bleeding Scalp Wounds

Rarely, bleeding from a scalp wound cannot be stopped using direct pressure or by infiltration of epinephrine-containing anesthetic agents. This is particularly true when tissue maceration has occurred due to blunt trauma. In this instance, it may be necessary to place deeper 2-0 or 3-0 absorbable sutures after wound cleansing to close the tissue defect and place an external pressure dressing. If a significant hematoma forms, it may be necessary to reexplore the wound and place an external drain.

When time allows, a closure with a running, locking 2-0 or 3-0 nonabsorbable suture may provide the best hemostasis and wound closure simultaneously.

Chemical Cautery

Silver nitrate and other caustics achieve hemostasis through tissue coagulation but are not recommended for wound hemostasis because of the amount of tissue necrosis they produce. American military forces are testing newer forms of powdered and gel adhesive procoagulants. Some of these generate high temperatures due to an exothermic chemical reaction, and reports of thermal tissue damage may limit utility in the civilian sector.

1This chapter is a revision of the revision by David A. Fritz, MD, FACEP, from the 6th edition.

History

A detailed, thorough history is essential for assessing the extent of injury and for organizing appropriate wound management. Three basic questions are used to reconstruct the history of the injury.

When Did the Injury Occur?

The time of injury is important for determining the interval between injury and treatment. Most civilian injuries contain fewer than 105 bacteria per gram of tissue in the first 6 hours and are therefore relatively safe to close. Wound repair after 6 hours is dependent on many factors, including vascularity of the area, degree of contamination, and health status of the patient. The longer the wound has been present, the more likely an infection will occur after primary closure. As a rule, tissue resistance to infection is directly proportionate to blood supply. Facial lacerations may often be closed safely within 24 hours of injury, owing to the abundant blood supply in that area.

Where Did the Injury Occur?

What were the possible contaminants associated with the injury? Contact with feces, pus, saliva, or soil greatly increases the risk of infection and should be considered when deciding on timing of closure.

How Did the Injury Occur?

The potential damage to deeper structures can be estimated by review of the mechanism of injury. Any high-velocity-missile injury has the potential to damage deeper structures, and the wound tract should be assessed carefully. Blunt injuries may crush tissue and fracture underlying bone, leaving an open fracture, compartment syndrome, or arterial disruption.

Types of Injuries

Lacerations

Lacerations cause minimal tissue injury and are relatively resistant to infection.

Puncture Wounds

Puncture wounds may become infected, especially if they are contaminated or if a foreign body is present.

Stretch Injuries

Stretch injuries can produce damage to blood vessels, nerves, ligaments, or tendons, which is not visible superficially.

Compression or Crush Injuries

Compression or crush injuries result in the greatest amount of tissue necrosis. Hemorrhage into the soft tissues is common, resulting in ecchymosis and hematoma formation. The crushed tissue has a markedly impaired ability to heal and resist infection. Depending on location, these injuries are at high risk to develop compartment syndrome.

Bites

Bites are heavily contaminated and may require delayed closure.

Examination

Complications arising from wound care are a common basis for malpractice claims against emergency physicians. Inspection should be conducted in an emergency care or surgical facility where adequate lighting and equipment are available. Wound hemostasis must be achieved for proper evaluation of involved structures and to rule out foreign bodies. The extra time spent in preparing the proper environment for wound examination often decreases total procedure time by facilitating the repair. Sterile technique and gentle handling of tissues are mandatory to avoid additional tissue injury or contamination.

If deep injuries cannot be assessed adequately through the existing surface defect, consider extending the laceration by undermining the skin beyond the wound edges with a scalpel. Obtaining sufficient exposure of the wound may reveal tendon injuries, joint capsule penetration, or foreign bodies.

Assess Type and Extent of Injury

In assessing the type and extent of injury, consider the following questions:

• Is there loss of function in the injured part?
• Are important underlying structures involved such as nerves, major blood vessels, ducts, ligaments, bones, or joints?
• What is the level of contamination in the wound?
• Are any foreign bodies present?
• What is the viability of the injured parts? Are any parts missing?

Tissue Avulsion

The viability of an avulsion flap depends not only on the vascularity of the flap but also on the length versus base ratio, maceration of the tissue involved, and vascularity of the surrounding tissue. A long flap of badly macerated tissue with a narrow base will probably not survive and should be excised while a clean, short flap on the face will almost certainly heal uneventfully.

Consider Location of Wound

Scalp

The blood supply to the scalp is excellent and wound infections rarely occur. The physician should examine scalp wounds carefully to ensure that the galea is not involved. Galeal lacerations should be cleaned and sutured with absorbable suture to prevent subgaleal hematoma formation and subsequent infection.

Face

Facial wounds can have dramatic effects on a patient's appearance; every effort should be made to minimize scarring and to prevent tissue loss. Debridement of facial tissue is rarely necessary and may cause distortion of features as the scar matures. Take special care with ear, eyelid, and nasal lacerations. Experienced emergency physicians maintain a low threshold for consulting their plastic surgery colleagues on complicated facial wounds.

Neck

Deep injuries to the neck frequently involve important underlying structures (Chapter 23). These complex anatomic areas cannot be extensively debrided without major functional or cosmetic loss. Wound evaluation and repair are often best done in the operating room by a maxillofacial, otolaryngology, or general surgeon.

Chest and Abdomen

Wounds of the chest and abdomen must be evaluated for possible communication with a body cavity as well as internal organ injury (Chapters 24 and 25).

Extremities

Hand injuries represent a significant proportion of emergency department patients and require special attention. Loss of function of even one digit can permanently impair a patient's ability to perform their vocation or avocation. Apparently minor puncture wounds may injure nerves, tendons, or arteries and cause significant impairment if not diagnosed during the initial presentation. Perform a complete neurovascular examination of every significant hand injury including function of the median, ulnar, and radial nerves (motor, light touch, and two-point discrimination); intrinsic hand muscles; extensor and both deep and superficial flexor tendons; radial and ulnar artery pulses; capillary refill; and wrist flexors and extensors.

Wounds on the plantar surface of the foot are particularly prone to infection. After thorough wound cleaning many emergency physicians will allow these wounds to heal without primary repair.

Prepare for Definitive Care

After initial assessment, cover the wound with a sterile dressing until definitive management, or further evaluation can be performed. Obtain any necessary X-rays only after the wound has been protected from the possibility of additional contamination. If considerable delay in definitive evaluation and management is anticipated, the wound should be cleaned, conservatively debrided, and temporarily closed or covered. Extensive wounds—or minor ones involving major structures—are best evaluated and managed in the operating room.

Anesthesia

Preliminary Examination

Perform a careful sensory and motor neurologic examination before administering anesthetic.

Choice of Agent

Local anesthetics have varying attributes with regard to safety, potency, duration of action, and effects on the local wound milieu (Table 30–1). Lidocaine is perhaps the safest local anesthetic, because allergic reactions are rare. The major problem with all local anesthetics is systemic absorption resulting in cardiovascular and central nervous system toxicity. For an adult, the maximum safe dose of 1% lidocaine without epinephrine is 5 mg/kg (do not exceed 300 mg) and for 1% lidocaine with epinephrine, 7 mg/kg (do not exceed 500 mg). For children, the safety and efficacy of lidocaine and mepivacaine are known; child safety and efficacy of the other drugs in Table 30–1 are not known.

Topical Anesthesia

Topical anesthesia is especially useful in the management of small wounds in children who do not tolerate local infiltration. A commonly used combination solution is LET (lidocaine, epinephrine, and tetracaine). TAC (tetracaine, adrenaline, and cocaine) has been largely abandoned due to risks of systemic toxicity and potential abuse. To apply the solution, soak a gauze pad in it and place the pad directly over the wound for 20 minutes. Do not use over mucous membranes or areas with end-arterial circulation (fingers, toes, nose, and penis). Anesthesia can often be judged by the appearance of blanching at the wound site. Use the minimal amount of anesthetic necessary.

Inhalation Anesthesia

Inhalation anesthesia with nitrous oxide administered by experienced personnel can be a useful adjunct, especially for children.

Local Infiltration

Infiltration of a local anesthetic agent is performed gently near the edge of the wound or directly into the wound with a small (No. 25–30) needle (Figure 30–1). Pain associated with local infiltration is partly due to the stretching of sensitive nerve endings in the dermis and may also be due in part to the difference in acidity of some anesthetics (the pH of commercial preparations of lidocaine is 5–7). Associated pain can be reduced by using smaller amounts of more concentrated anesthetic solutions and slower infiltration rates or, in the case of lidocaine, by preparing it as a buffered solution (9 mL of 1% lidocaine, to which 1 mL of sodium bicarbonate solution, 44 mEq/50 mL, is added). Restrict the dose of anesthetic to the least amount that will provide adequate anesthesia. This is particularly true for facial lacerations, where infiltration distorts important landmarks and makes precise matching of wound edges difficult. Infiltration of anesthetic directly into the wound is less painful but may spread infection in heavily contaminated wounds.

Injecting a small skin wheal and then advancing slowly, pausing to let each increment of tissue become anesthetized, is a more time-consuming method but less painful to the patient.

Regional Anesthesia

Regional anesthesia (sensory nerve blockage at a site proximal to the wound) is more technically challenging than local anesthesia, but it provides a larger anesthetic area and allows more extensive exploration and manipulation of the tissues. Because local wound anatomy is not distorted by regional block, more precise alignment of wound edges is possible. Onset of anesthesia is a function of the type of agent used and how close to the nerves the agent is injected. The duration of anesthesia can be prolonged with epinephrine; however, epinephrine should not be used for digital nerve blocks. Regional anesthesia is particularly suitable for extremity injuries complicated by heavy contamination or in extensive injury requiring long operating times for repair. It is also used in patients who are not good candidates for general anesthesia.

Pitfalls of Regional Anesthesia

Pitfalls of regional anesthesia include difficulty in placing the anesthetic close to the supplying sensory nerve; loss of valuable time in waiting for it to take effect; and risk of permanent injury to the nerve from direct infiltration of anesthetic into the nerve.

Common Regional Blocks for Hand Surgery

Several techniques for regional blocks in hand surgery are described below. Whatever the method used, a thorough understanding of anatomy is crucial. Avoid probing injections because of the risk of paresthesias. Attempt to infiltrate the anesthetic without penetrating the nerve sheath, because this may injure the nerve.

Use a 25- or 27-gauge needle; larger needles may cause significant nerve injury. Wait about 10 minutes for the full anesthetic effect in digital blocks and 20 minutes for wrist blocks.

Digital Block

The technique requires two separate needle sticks with four injections of 1 mL of 1% lidocaine next to the nerve bundle of all four digital nerves. The needle is first inserted dorsally to block the dorsal digital nerve and is then redirected without removal toward the volar nerve and the anesthetic is injected. The procedure is repeated on the opposite side of the digit.

Radial Nerve Block

The radial sensory nerve emerges beneath the brachioradialis tendon (Figure 30–2) about 6 cm (2 ⅜ in) above the Lister tubercle. Inject about 4 mL of lidocaine in a 2-cm (¾ in) wide band 4 cm (1 in) above the Lister tubercle.

Median Nerve Block

The median nerve at the wrist lies just radial and deep to the palmaris longus tendon and the transverse carpal ligament (Figure 30–3). The palmaris longus, when present, is easily identified by having the patient make a fist and flex the wrist. Insert the needle dorsally and distally between the palmaris longus and flexor carpi radialis, and inject 4 mL. The lidocaine can be milked into the carpal tunnel to achieve the maximum blocking effect.

Ulnar Nerve Block

The ulnar nerve and artery course just dorsal to the flexor carpi ulnaris at the wrist (Figure 30–4). Avoid inadvertent injection of anesthetic into the artery by aspirating as the needle is advanced. Inject 2 mL on the ulnar side of the flexor carpi ulnaris. An additional 2 mL should be injected on the radial side to achieve a total block.

Common Regional Blocks for Facial Surgery

Infraorbital Nerve Block

The infraorbital foramen can be easily palpated along the anterior maxilla and lies along a line drawn between the pupil and the maxillary canine. Inject about 1–2 mL as the needle is advanced from a lateral to a medial direction (Figure 30–5). Avoid penetrating the nerve by being careful not to enter the foramen. An intraoral approach may also be used. Wait for symptoms of numbness of the upper lip. Infraorbital nerve block provides anesthesia of the cheek, upper lip, and parts of the nose.

Supraorbital Nerve Block

The exit of the supraorbital nerve from the orbit is readily identified by palpating the supraorbital notch. Inject a total of 1–2 mL of anesthetic about 0.5 cm (3/16 in) above the orbital rim (Figure 30–6). Advance the needle from a lateral to a medial direction, and avoid penetrating the nerve. If both supraorbital and infratrochlear blocks are needed, the wheal should be extended medially toward the midline. Supraorbital block is useful in anesthetizing the forehead.

Cleaning and Debridement

Hair Removal

Wounds in hairy areas are difficult to debride and suture, and hair in a wound acts as a foreign body, delaying healing, and promoting infection. Shaving hair around wound edges facilitates management but invites wound infection if the infundibulum of the hair follicle is injured. Contamination can be minimized by clipping the hair 1–2 mm (1/16 in) above the level of the skin. Depilatory agents and special razors equipped with recessed blades also allow safe removal of hair without infundibular injury.

A method of scalp laceration repair using the native hair to tie wound edges together has been described and seems to have no increased risk of infection when compared to standard suture repair. Reports of the hair spontaneously untying have led some physicians to place a drop of skin adhesive to the hair after tying.

Caution: Eyebrow and eyelash hair should never be removed, since removal destroys critical landmarks and makes accurate alignment of wound edges difficult. Misalignments may cause notch or step-off deformities in the brow line. Eyebrow hair also regrows slowly, creating a cosmetic problem.

Mechanical Cleansing

As an adjunct to surgical debridement, mechanical cleansing of the wound by irrigation or scrubbing is quite effective. Soaps and detergents should not be used in the open wound in conjunction with mechanical cleaning.

Irrigation

The most reliable and well-tested method of emergency wound cleaning is high-pressure irrigation with normal saline. Pressures of 7–11 lb/in2 must be achieved to mechanically remove bacteria and particulate debris.

Numerous commercial devices are available for high-pressure irrigation, but the simplest and least expensive is syringe irrigation. A 35- or 50-mL syringe and a 19-gauge or blunt needle connected to a reservoir of irrigating fluid by a three-way stopcock are suitable. Commercial splash guards are also available, which attach to a syringe and allow for the requiredpressure while providing protection from bodily fluids.

Bulb syringe irrigation has been shown to be no more effective in preventing wound infection than no irrigation at all. Soaking wounds in saline does not remove bacteria and may allow for further contamination of the wound. The commonly used method of puncturing holes in the cap of a plastic liter bottle of saline and squeezing the contents into the wound does not achieve the necessary pressure to remove significant amounts of bacteria and should no longer be used.

Normal saline (or similar balanced crystalloid solution) is forcefully injected close to the wound surface and perpendicular to the surface of the skin. The amount of irrigant used depends on the size of the wound and the suspected extent of contamination.

Since large volume irrigation is preferred, when the wound can be placed under a faucet supplied by chlorinated city water, the wound may be irrigated in this fashion since studies have not shown an increased risk of infection as compared with sterile saline.

Mechanical Scrubbing

1. Sponge—Mechanical scrubbing of the wound surface is usually best performed with a highly porous sponge. Sponges routinely used for hand washing work well. Brushes and low-porosity sponges decrease the wound's resistance to infection.

2. Brush—“Abrasion tattooing,” in which debris is embedded in the skin, requires vigorous scrubbing or dermabrasion to remove embedded debris. Soaps and detergents should not be used.

Skin and Wound Cleansers

Cleanse the wound and surrounding skin to remove transient microflora, gross debris, coagulated blood, and the like.

Normal Saline

In most instances, simply washing the open wound with saline under pressure (see above) removes most of the surface bacteria.

Nonionic Surfactant

The nonionic surfactant Pluronic polyol F-68 has been shown to be effective as a wound cleansing agent without demonstrably impairing resistance to infection or wound healing.

Hydrogen Peroxide

The foaming action of hydrogen peroxide is frequently used to remove particulate debris and recently clotted blood from wounds. A dilute solution of hydrogen peroxide is very useful for removing dried blood and debris from around wound edges. Undiluted hydrogen peroxide should not be used directly in a wound due to risk of cytotoxicity.

Ionic Soaps and Detergents

Ionic soaps and detergents (eg, pHisoHex) should not be used for wound cleansing, because they are extremely irritating to tissues and increase the potential for infection if used directly on the wound. They may be used for cleansing of intact skin surrounding the wound, although they have not been shown to be superior to ordinary soap or other agents for this purpose. After application, they should be removed by thorough rinsing with water.

Skin Disinfectants and Antimicrobials

The use of 1% povidone-iodine to irrigate wounds is widely debated. It is effective as a skin disinfectant prior to surgery, but concentrated iodine is cytotoxic. There is probably no significant advantage or disadvantage to dilute povidone-iodine solution compared to normal saline. Irrigation of wounds with antibiotic solutions has been associated with a slightly decreased rate of wound infection but at a much greater cost.

Debridement

Remove retained debris and devitalized tissue by surgical excision and mechanical cleansing. Surgical debridement consists of excising devitalized or severely contaminated tissues and irregular areas that interfere with wound closure. Use a stainless steel scalpel blade for debridement. Facial tissue should only be debrided by the appropriate surgical specialist.

Total Excision of the Wound

The simplest method of debridement is total excision of the wound, creating a surgically clean area. Caution: Total excision is appropriate only for wounds that do not involve specialized structures (eg, injuries of the abdominal wall and thighs). More selective debridement is indicated for wounds on the hand or face.

Selective Debridement

In most situations, it is best to mechanically cleanse the wound and then perform selective debridement of all grossly nonviable tissue. Signs of tissue necrosis include gray or black color and lack of bleeding when the tissue is incised. Remove all nonviable portions. Mangled, irregular wound edges imply severe local tissue injury and should be sharply debrided. If it appears that adequate debridement would prevent tension-free simple closure, consult an experienced surgeon for wound management.

Excision procedures on the face, particularly those on specialized structures, such as the ear or nose, require a conservative approach. The facial area has an abundant blood supply that enables tissues to survive on surprisingly small pedicles. In these cases, observation and expectant treatment are warranted. Obtain surgical consultation before performing any debridement of a specialized part.

Wound Closure

After the wound has been examined, anesthetized, cleaned and debrided, and reexamined, the physician must decide whether to close it. Primary wound closure is preferable because of faster healing, less scarring, improved hemostasis, and better aesthetic and functional results. All foreign bodies must be removed to minimize the chance of infection.

Contraindications to Wound Closure

Several factors affect the risk of infection with wound closure and determine whether closure is justified.

Heavy Bacterial Colonization

A prolonged interval (more than 6 hours) between injury and attempted closure may be a contraindication to wound closure. In a generously vascularized area such as the face, wound closure may be attempted up to 24 hours after injury. Heavily contaminated wounds (eg, bites) should be left open. Active wound infection at the time of the emergency department visit contraindicates closure of the wound.

Major Tissue Defects

Closure is contraindicated if the wound cannot be closed without excessive tension.

Other Factors

Closure is contraindicated if there are retained foreign bodies, devitalized tissue, or tissue with borderline per-fusion.

Primary Closure

The objectives of primary wound closure are (1) precise alignment of injured parts to facilitate rapid healing, return of function, and a good cosmetic result and (2) avoidance of tissue injury (eg, excessive electrocautery, strangulating sutures), hematoma formation, and wound tension.

Delayed Primary Closure

Contaminated wounds, if properly debrided, will gain resistance to infection if left open. After 48–96 hours, these wounds can then be closed with essentially no loss in wound healing time. Consider delayed primary closure in the case of wounds contaminated by feces, pus, foreign body, or saliva in the case of bite wounds. Crush and blast injuries and avulsion injuries are markedly susceptible to infection and necrosis and should also be considered for delayed closure.

After initial debridement, gently pack the wound with saline moistened fine-mesh gauze. This should be changed 1–3 times a day until closure of the wound. This method requires a dependable patient, and interim wound checks may be indicated. The wound should be examined for signs of infection at follow-up. If no infection is suspected, the wound can be closed in the same manner as in primary closure.

Suture Selection

All sutures represent foreign bodies in the wound. For this reason, use the smallest size and the least amount of suture that will achieve adequate tissue apposition.

The size and location of the wound and the desired precision of closure generally dictate the choice of needle and suture size. Generally, fine sutures are used in wounds (or their parts) requiring precise alignment; 5-0 and 6-0 sutures are preferred for closure of facial lacerations. Layered closure (fascia, dermis) of any wound allows placement of fine epidermal sutures anywhere on the body. The epidermis itself has little tensile strength, and sutures are placed in this layer only to achieve accurate alignment of wound edges.

Percutaneous closure of the epidermis and dermis in regions other than the face is best managed by the use of 3-0 or 4-0 suture material. Suture marks are the result of tension in the tied suture and the length of time the suture is left in place.

Absorbable Sutures

Absorbable sutures are biodegraded and lose their tensile strength in 2–6 weeks.

Gut Sutures

Sutures derived from sheep submucosa or beef serosa are digested by proteolytic enzymes in the wound. They are more rapidly degraded in the presence of infection. The knot-holding ability of plain gut is rather inconsistent; chromic gut seems to be better in this regard.

1. Plain gut—Plain gut incites an intense inflammatory reaction in the wound and loses its tensile strength within 2 weeks.

2. Chromic gut—Treatment of gut with chromium salts decreases its tissue reactivity and prolongs its survival to about double that of plain gut. In some studies, however, it has been shown to potentiate infection more than the plain gut.

Synthetic Sutures

Polyglycolic acid (Dexon), polyglactin (Vicryl), and polydioxanone (PDS) produce minimal tissue reaction in the wound and are most commonly used for dermal and subcutaneous closures and vascular ligation.

1. Degradation—Polyglycolic acid and polyglactin are degraded by hydrolysis and lose 50% of their tensile strength in 14–20 days and about 90% by the fourth week (comparable to chromic catgut). Polydioxanone, a third-generation synthetic absorbable suture, loses 50% of its tensile strength in 5 weeks and 90% at 2 months.

2. Tying qualities—Although similar to silk in their handling characteristics, polyglycolic acid and polyglactin sutures do not hold knots quite as well. Polydioxanone looks, feels, and handles like monofilament nylon or polypropylene.

3. Use in acute wounds—Absorbable synthetic sutures are probably superior to gut sutures in acute wounds because of their low tissue reactivity and resistance to degradation in the presence of infection. The monofilament characteristics of polydioxanone make it almost the ideal synthetic absorbable suture.

Nonabsorbable Sutures

Nonabsorbable sutures are degraded very slowly or not at all in the tissues.

Silk

Silk sutures represent the most common type of natural fiber suture. Silk gradually loses its tensile strength and is classified as a slowly absorbable suture material. The tissue reactivity of silk is the greatest of all nonabsorbable sutures, and its use in acute wounds has generally been abandoned.

Synthetic Sutures

1. Dacron—Dacron is a polyester that elicits less tissue reaction than silk. Because of its high friction coefficient, it is as difficult to handle as a suture. The friction injury imposed on the tissues by Dacron can be overcome by coating it with Teflon.

2. Nylon—Nylon causes less tissue reactivity than Dacron, and its use in contaminated wounds results in lower wound infection rates. Monofilament nylon sutures lose approximately 20% of their tensile strength within a year after placement in a wound. The monofilament form of nylon is quite stiff and does not hold knots well. Multifilament nylon sutures completely lose their tensile strength in the wound after 6 months, but they are easier to tie than monofilament sutures.

3. Polypropylene and polyester—Polypropylene and polyester materials cause the least reactivity of all suture materials. They maintain their tensile strength indefinitely and are the suture material of choice for closure of contaminated wounds. These materials are used most commonly for fascia and skin closure. They are also advantageous in the repair of vascular, nerve, and tendon injuries. Because of their softer consistency, these materials generally hold knots better than does nylon.

Wound Tapes

Sutureless closure of the acute wound provides maximum resistance to infection. Various tape materials have been used and have resulted in significantly diminished wound infection rates compared to those in suture closure. Tape closure is most advantageous in the contaminated wound but is also useful in superficial clean and tidy wounds, wounds in children, and wounds in obese patients.

Tape closure is inferior to suture closure in maintaining precise wound edge alignment and eversion, requisites for cosmetically acceptable closure. However, tape closure is often used after early removal of sutures in order to minimize suture marks and to provide additional splinting of the wound until tensile strength is sufficient to resist local forces tending to pull the edges of the wound apart.

Attributes of Wound Tapes

To be effective, skin tapes must be strong enough to support the wound edges in close apposition until sufficient healing has occurred. The tapes must have excellent skin adherence and should not macerate the underlying skin surface. Removing all moisture and using a defatting agent (eg, acetone) enhances adhesiveness to the skin, and tapes so applied will adhere for up to 2 weeks. Although tincture of benzoin is occasionally used to increase adhesiveness and may initially enhance tape adhesion, it is solubilized by skin oils and rapidly loses its effectiveness.

Wound Tapes over Deep Sutures

Suture closure in irregular lacerations and crush injuries allows for better approximation of skin edges than does tape closure. Moreover, tape only approximates the superficial portion of the wound, leaving the deeper wound layers more vulnerable to local biomechanical stresses and resulting in a weak, unsightly scar. In clean wounds, it is sometimes preferable to close the deeper layers with sutures and then approximate the superficial layers with tape.

Metallic Staples

Many types of disposable skin staple devices are available. The staple configurations vary but are primarily designed to approximate wound edges with minimal tissue trauma. Some staples project above the skin surface to avoid staple marks. As with wound tapes, precise epidermal alignment is difficult to achieve with a skin staple, and these devices should not be used for cosmetic skin closures. Because a stapled wound usually does not contain dermal sutures, its tensile strength depends on the presence of the staple, and this must be kept in mind when considering staple closure of wounds subjected to increased tension (eg, joint surfaces, mobile parts). If early removal of the staple is contemplated, the wound should be supported by skin tapes until the wound gains sufficient tensile strength to withstand local biomechanical forces. The time required varies from 1 to 2 weeks depending on the wound's location.

Tissue Adhesives

Cyanoacrylate tissue adhesives (Dermabond) are widely available. These adhesives polymerize rapidly when applied to tissues and form an adhesive layer on top of intact epithelium to hold the wound edges together. These adhesives cause an intense inflammatory reaction and should be used only on minor superficial lacerations. They should not be used near the eye, on mucous membranes or mucosal surfaces, on moist areas, or on areas with dense hair. Tissue adhesives should not be used for infected wounds.

Tissue adhesives are useful for minor wounds, those less than 5 cm in length and with separated wound edges less than 0.5 cm; they are most beneficial for wounds that would close spontaneously. Wounds greater than 5 cm in length and 0.5 cm in separation have increased tensile forces that may lead to poor wound edge approximation and a poor cosmetic outcome. Subcutaneous sutures may be useful in decreasing wound edge tension and may lead to a far better cosmetic result.

Preparation of wounds for closure with tissue adhesives is the same as that for sutures. Thoroughly cleanse the wound and control bleeding before applying tissue adhesive. Hold the wound edges together and slightly everted with tissue forceps. Apply the adhesive by lightly wiping the applicator tip in the direction of the long axis. Apply a few layers quickly and then hold the wound edges together for about 60 seconds to ensure adequate bonding. Once applied, tissue adhesives should not be covered with ointment, skin tapes, or dressing. If any adhesive is applied to unwanted areas, it can be removed with petroleum jelly or acetone (nail polish remover). Many tissue adhesives are commercially available, with many different applicator sizes and applicator tips. Also available are accessories to assist with the entire procedure, from wound cleansing devices to tissue forceps of various sizes and shapes for any size or shape wound.

Among the benefits of tissue adhesives is better cosmetic appearance, if used appropriately. The manufacturer of Dermabond states that the incidence of wound infection with this product is 3.6% and the incidence of dehiscence requiring retreatment is 2.2%; neither finding was statistically different on comparison with wounds closed with sutures.

Choice of Closure Technique

The choice of an appropriate material for wound closure is based on biologic and mechanical properties of the material and the characteristics of the wound. Decisions about layers to be closed are based on several factors, the most important of which are stress, dead space, and skin approximation.

Fascia

In soft tissue wounds that do not involve the face, the strength of closure depends on the fascia. Because fascia heals slowly, the suture material should be capable of maintaining its strength for a long time. Synthetic nonabsorbable sutures are best for this purpose.

Muscle and Fat

Muscle and fat do not hold sutures well, and closure is performed primarily to obliterate dead space. Dead space results from traumatic tissue loss, debridement, or gaping of subcutaneous layers. Suturing of dead space invariably produces additional tissue trauma and necrosis and is contraindicated in the closure of contaminated wounds. When such suturing is performed, it should be accomplished with the fewest possible loosely placed sutures. Chromic gut or one of the synthetic absorbable sutures should be used for this purpose.

Skin

Skin closure may be accomplished by layers, full-thickness percutaneous sutures, skin tapes, or a combination of these methods. The type of skin closure method chosen depends on the forces tending to open the wound and how good a cosmetic result is desired. The width of the scar that will result from healing will be influenced by the local stresses of the surrounding tissues. The direction of maximum force of skin tension is usually parallel to the skin wrinkles. Wounds oriented in the same direction as local stresses are subjected to less tension during healing and consequently produce a less visible scar. Examples include transverse lacerations of the forehead and vertical lacerations of the upper lip. Wounds that cross lines of maximal skin stress will be subjected to increased tension during healing. These wounds frequently widen with time and have a tendency to form hypertrophic scars. Examples are transverse lacerations of the cheek and axial lacerations over the elbows.

The propensity of a scar to hypertrophy is also influenced by factors unrelated to its location or technique of closure. The tendency of children and adolescents to form hypertrophic scars is notorious and is probably influenced by elevated levels of growth hormone or other growth factors. Pregnant women have an increased incidence of hypertrophic scar formation that decreases with the resumption of normal menses after delivery; this tendency is often associated with a parallel increase in pigmentation coinciding with pregnancy. Some investigators have postulated that hypertrophic scars and pigmentation are under similar hormonal influences. An increased incidence of hypertrophic scar and keloid formation is also found in blacks and other dark-skinned races. These specific groups of patients will demonstrate an exaggerated scar formation response that can be controlled only by manipulation of the wound in ways beyond the technical aspects of closure. Not all patients in these groups will form hypertrophic scars, however, and it is impossible to predict which patients might, except perhaps in the case of patients who have a history of hypertrophic scar formation. In these patients, precise wound closure using fine suture materials and atraumatic technique may lessen the degree of hypertrophic scarring that might otherwise result. In the acute wound, however, primary consideration is given to the location and orientation of the wound and its method of closure.

Drainage of the Wound

Drains constitute foreign bodies, produce tissue necrosis, serve as conduits for bacterial contamination of the wound, and are not very effective in preventing hematoma formation. If sound principles of management have been carefully followed, drains are usually unnecessary in the acute wound. If oozing cannot be controlled, it is preferable to delay wound closure. Drains, however, may be effective in evacuating pus and necrotic exudates that might be found in heavily contaminated or already infected wounds.

Postoperative Wound Care and Dressings

Postoperative wound care should provide an ideal environment for wound healing. This is accomplished primarily through the use of dressings. A dressing serves one or more of seven different functions: protection, immobilization, control of edema (compression), absorption, debridement, delivery of topical medications (antibiotics), and cosmetic appearance.

Wounds closed by percutaneous sutures are susceptible to surface bacterial invasion for the first 48 hours after closure. During this time, the wound should be protected with sterile dressings or frequent suture line care.

Dressing a Wound

If dressings are used, nonadherent materials (eg, Telfa, petrolatum-impregnated gauze) are favored because removal is easy and does not disturb sutures or coated wound edges.

Petrolatum-impregnated dressings have been shown to decrease the rate of epithelialization in partial-thickness wounds. For this reason, ointment-impregnated dressings (eg, bacitracin, polymyxin B sulfate, or nonadherent occlusive dressings) are preferred for this particular type of wound. Neomycin has a risk or allergy that rivals the rate of wound infection, and since a local allergic reaction and a wound infection have similar characteristics, neomycin use should be cautioned.

Occlusive or semiocclusive polyurethane, methacry-late, silicone polymer, or gel dressings provide excellent protection, and most do not alter the rate of normal epithelialization. If the wound contains residual necrotic debris or significant levels of bacterial contamination, however, the risk of wound infection is increased with these dressings.

Undressed Wounds

Suture line care without a dressing is commonly used for facial wounds and involves frequent meticulous cleansing with saline or dilute hydrogen peroxide solution. Cleansing removes the adherent coagulum from the suture–skin juncture, decreasing the likelihood of stitch abscess formation. After cleansing, the wound is dressed with an antibiotic cream or ointment (eg, bacitracin and polymyxin B sulfate).

Tape Dressings

Taped wounds are quite resistant to surface bacterial contamination. They usually require no protection other than that provided by the tape itself. These wounds should be checked frequently for wound drainage beneath the tape. Excessive drainage can cause maceration of the wound edge and thereby provide an excellent medium for bacterial proliferation.

Immobilization

Immobilization of the wound enhances resistance to infection, reduces sheer forces, and may accelerate healing.

Materials

Immobilization is accomplished with splints, bulky dressings, skin tapes, or combinations of these methods.

Duration of Immobilization

Ideally, immobilization of the wound should be continued until it is no longer vulnerable to infection and has gained sufficient strength to withstand the stresses of motion and skin tension. Wounds become resistant to infection within a week, but development of maximal strength requires about 6 weeks. Protracted immobilization will defeat its possible advantages, for example, possibly producing permanent joint contractures in elderly persons or promoting formation of deep venous thrombi. The advantages of wound immobilization must be weighed against the undesirable consequences.

Control of Edema

Edema slows tissue healing and increases pain. Edema increases in the first 48 hours postinjury and subsides over the next 5 days. The main methods of edema control are elevation of the wound and compression dressings.

Elevation

Elevation of the wound above the level of the heart is the simplest way to limit the amount of excess tissue fluid in the wound. Slings are generally not useful in this regard. Advise the patient to elevate the wound above the level of the shoulders while at rest. One simple way to achieve this is place a pillow on the chest while in the semirecumbent position and placing the arm and hand on top.

Compression Dressing

In certain situations, it is advantageous to “apply pressure over the wound along with elevation by using bulky pressure dressings.”

Caution: Compression dressings should not be used in crush injuries or in injuries that tend to develop into compartment syndromes (eg, severe injuries of the forearm or leg). Continued pain or diminished sensitivity necessitates removal of the dressing and careful examination of the wound. Although these dressings are often used to absorb bloody oozing at the operative site, they should not be used as a substitute for diligent hemostasis.

Avoid constriction of proximal parts with these dressings, because venous and lymphatic congestion will occur as result of the tourniquet effect.

Bony prominences must be carefully padded, with generous use of bulk. To ensure uniform compression throughout and to avoid constriction and pressure-point injury, smooth, even wrapping that avoids lumps is necessary when compression dressing is applied.

In managing hand wounds, it is important to place 1 or 2 layers of gauze between the fingers to prevent maceration. The toes and fingertips should be exposed so that the physician can assess sensibility and capillary refill. Rolled gauze or bias-cut stockinet is preferred over elastic bandages, which are often too constricting. The finished dressing should be firm but not strangulating.

In extremity injuries, compression dressing should extend proximally from the most distal point. For example, a wound of the forearm requiring a compression dressing is managed by applying the dressing starting from the fingers to above the wound.

Absorption

The absorptive capabilities of a dressing are used to remove bloody and serous ooze from the wound or drainage site.

Closed Wounds

In closed wounds, dry dressings are preferable, because moist ones will cause maceration of the skin and invite bacterial invasion.

Open Wounds

In open wounds, it is preferable to apply moist dressings to the open wound surface and back them with dry dressings to achieve a capillary effect. The exception to this principle is deep, tunnel-shaped wounds, where surface evaporation is limited, thus diminishing the capillary effect. These wounds are best managed by packing with dry gauze to achieve maximum absorption.

Materials

In all instances, absorptive dressings should be composed of fine-mesh gauze or spun fabric.

Caution: Absorbant dressing must be changed frequently to avoid the proliferation of toxin-producing bacteria. Absorbant dressing have been associated with toxic shock syndrome.

Debridement

Dressings are frequently used for mechanical debridement of the open wound. The traditional wet-to-dry method utilizes avulsion of adherent tissues to remove devitalized remnants from the wound surface. Unfortunately, this method does not discriminate between viable and nonviable elements and reinjures the wound with each dressing change. Although painful and detrimental to wound healing, this method is effective in removing fine tenacious material from the wound surface. It should be discontinued as soon as the desired effect has been achieved.

The technique is as follows: Several layers of moist gauze are applied to the wound surface and allowed to dry. After about 4 hours, the adherent dressing is removed. Moistening the dry dressing before removal to loosen the dressing and lessen the pain of removal (as may be done by a sympathetic hospital attendant) defeats the purpose.

Delivery of Topical Antibiotics

The most common medicaments used in a dressing are antibacterials. Topical antibacterials are used to control bacteria that cannot be reached by systemic agents. They are not a substitute for adequate debridement.

Topical Antibacterial Agents

Mafenide (Sulfamylon) and silver sulfadiazine (Silvadene) are most effective in this regard. These agents are also useful in partial-thickness injuries or marginally viable tissues (eg, abrasions, burns, crush injuries). By decreasing the potential for bacterial invasion, they diminish the likelihood of infection and the resulting tissue necrosis.

Adverse Reactions

Use of these agents must be monitored closely, because excessive amounts may cause acid–base imbalances (mafenide) or leukopenia (silver sulfadiazine). Both agents retard wound epithelialization and should be discontinued when the necrotic debris has been removed and wound bacterial counts are fewer than 105 organisms per gram of tissue.

Cosmetic Appearance

To the patient or casual observer, the sight of a wound is abhorrent and may be an occasion for adverse response. A dressing hides the wound and allows the patient to proceed with the process of rehabilitation without that distraction. In addition, a carefully applied, neat-appearing dressing reassures the patient that good wound care has been provided.

Potential Infections and Antimicrobials

Antimicrobials may be effective in preventing wound infection, particularly when the wound has fewer than 106 organisms per gram of tissue before treatment is started. Wounds with more than 106 organisms per gram of tissue often become infected despite antibiotic prophylaxis and should be left open. Systemic antibiotics, to be effective, must be started as soon as possible following injury, preferably within 4 hours. Topical antibiotics are commonly used to suppress bacterial growth, although their efficacy at preventing subsequent infection is probably low. The likelihood of wound infection must be judged by the mechanism of injury, the level of contamination, the adequacy of debridement, and the patient's general health status.

If adequate wound management must be delayed for any reason, then consider systemic antimicrobial prophylaxis.

Sharp, clean lacerations are markedly resistant to infection and in most instances will not require chemoprophylaxis. Open wounds, by virtue of their inflammatory response and resistance to bacterial dissemination, rarely become infected unless the initial level of contamination is great and cannot be reduced by cleansing and debridement. Furthermore, the fibrinous coagulum in these wounds limits the possible effectiveness of systemic antimicrobials on bacterial contaminants, thus making their use impractical.

Deep wounds or those that involve poorly vascularized structures such as bone, tendon, ligament, or fascia should be treated with systemic antibiotics prophylactically. Oral mucosal lacerations rarely require systemic antibiotic prophylaxis, because the infection rate is low and randomized trials have not demonstrated a benefit from such treatment. Grossly contaminated wounds such as those that come in contact with feces, pus, or saliva should not be closed. Systemic antimicrobial therapy is mandatory. The choice of drug is based on the suspected predominant pathogen (Table 30–2).

Tetanus Immunization Status

Tetanus has become rare in civilized countries due to emphasis on immunization. Tetanus is more likely to occur in IV drug abusers, immigrants, and older adults, particularly women. Table 30–3 shows the recommended tetanus immunization guidelines based on immunization history and wound type. Tetanus toxoid should be administered to anyone who has not received a booster within 10 years or who has not completed the primary series of three doses. Td (tetanus toxoid combined with adult-dose diphtheria toxoid) is preferable to tetanus toxoid alone. If passive immunization is required, human tetanus immune globulin is indicated. The recommended dose is 250 units intramuscularly. If both Td and tetanus immune globulin or antitoxin are given, they should be administered in separate sites using separate syringes.

Rabies Prophylaxis

Assess Risk of Rabies Exposure

See Figure 30–7.

Species of Biting Animal

Carnivorous animals (especially skunks, foxes, badgers, bobcats, coyotes, raccoons, dogs, and cats) and bats are more likely to be infected and are vectors for rabies. Lagomorphs (rabbits and hares), Picas (chinchillas), and Rodents (squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, and mice) rarely transmit rabies in the United States.

Determine If Animal Is Rabid (If Possible)

(Note: Behavior is not a reliable sign of the rabid state.) If examination of the animal's brain for rabies is negative, it can be assumed that the animal's saliva did not contain rabies virus.

Healthy domestic dogs and cats should be observed for 10 days by a veterinarian. If signs of rabies develop, the animal should be killed and its brain examined for rabies virus at the local public health laboratory.

Stray or unwanted dogs and cats that cause bites should be euthanized immediately and the brain examined for rabies. Wild animals that cause bites should be sacrificed immediately and the brain examined for rabies.

Circumstances of Biting Incident

Unprovoked attacks are more likely to mean that the animal is rabid; unfortunately, it may be difficult to distinguish between normal defensive or territorial behavior. Bites from apparently healthy animals that are fighting or feeding or that have been picked up or petted should be considered provoked and so have a low likelihood of causing rabies.

Types of Exposure

Any penetration of skin by teeth is regarded as a bite. Nonbite exposure consists of contamination of scratches, abrasions, mucous membranes, or previous wounds with infected animal saliva. Finding a bat within a bedroom, regardless of presence or absence of bite marks or the proximity of the animal to humans, should be considered an exposure.

Rabies Immunization Status of Animal

Vaccines are effective for cats and dogs but are not effective in preventing rabies in other animals, especially wild animals that have been domesticated (eg, pet skunks and foxes).

Prevalence of Rabies in Region

Certain areas are devoid of rabies (eg, San Francisco, Alaska, and Great Britain). Some rural areas are considered at high risk for rabies (eg, Texas–Mexico border).

Management of Patients at High Risk

Provide tetanus prophylaxis (see above), and give antibiotics if indicated (see above). Quickly administer appropriate postexposure rabies prophylaxis (see Figure 30–7 and Tables 30–4 and 30–5).

Act quickly! The sooner antirabies measures are instituted, the more effective they are.

Wound Care

This is the most important step. Wash the wound copiously with 20% green soap tincture and water. Quaternary ammonium compounds and alcohol are no longer recommended.

Passive Immunization

1. 1. Rabies immune globulin USP—This neutralizing antibody should be given to all patients except those previously immunized who have documented antibody titers or those who have received preexposure human diploid cell rabies vaccine prophylaxis or a full course of human diploid cell rabies vaccine. Give 20 IU/kg at the onset of rabies therapy; rabies immune globulin can be given as late as the eighth day if necessary. The full dose of rabies immune globulin should be thoroughly infiltrated in and around the wound; any remaining rabies immune globulin should be injected intramuscularly at a site distant from vaccine administration. Because rabies immune globulin may partially suppress the antibody response to vaccine, no more than the recommended dose should be given.

Active Immunization

Human diploid cell rabies vaccine is an inactivated virus vaccine prepared from rabies virus grown on human diploid fibroblasts. Give four 1-mL doses intramuscularly on specified days. The first dose is given as soon as possible after the bite; subsequent doses are given on days 3, 7, and 14. An alternative immunization is the chick embryo cell vaccine (PCECV) given at the same dose and schedule.

If preexposure human diploid cell rabies vaccine prophylaxis and adequate booster doses have been given (because of occupation as a veterinarian, for example), only two 1-mL intramuscular doses of human diploid cell rabies vaccine are needed, one as soon as possible after the bite and the other 3 days later.

Routine serologic testing after treatment with human diploid cell rabies vaccine is not necessary unless the patient is immunocompromised or is taking corticosteroids. Individuals taking steroids should discontinue the medication while receiving antirabies treatment.

Follow-Up Care of the Wound

Patients must be given verbal and written instructions specifically describing wound care, how to recognize infection, and when to return for wound checks or suture removal.

Suture Removal

The timing of suture removal depends on many factors such as location; type of wound closure; presence of infection; and the patient's age, health, and compliance. Table 30–6 is a general guideline for suture removal in healthy adults with uncomplicated wounds. Modifications of these recommendations should be tailored to individual patients.

Facial Lacerations

See Chapter 23.

Intraoral Lacerations

Lacerations of the oral mucosa and tongue may not require closure if they are small. The rich blood supply promotes rapid healing, and cosmetic considerations are minimal. However, large or gaping wounds, through-and-through lacerations, and lacerations involving important deep structures, such as muscle or bone, require repair. In such wounds, after irrigation with saline, disrupted muscle should first be approximated with absorbable suture (eg, 5-0 Vicryl) and the mucosa closed with absorbable suture (eg, 5-0 chromic gut or Vicryl). It is best to use the minimum number of sutures that will allow approximation of the wound edges.

Through-and-through lacerations of the lip merit special attention:

1. Irrigate the wound thoroughly, inside and out. A dry gauze roll between the lip and teeth will help prevent recontamination of the irrigated wound.

2. Close the mucosal laceration with absorbable suture (eg, 5-0 chromic gut or Vicryl).

3. Irrigate the wound again from the outside. The sutured mucosa will prevent reentry of saliva.

4. If the orbicularis oris muscle is disrupted, approximate it with absorbable suture (eg, 5-0 Vicryl).

5. Close the external skin with interrupted sutures of 6-0 monofilament nylon. Take extreme care to line up the opposing vermilion borders of the lip.

6. Examine the adjacent teeth that produced the wound; they may be fractured or avulsed.

Blast Injuries

Clinical Findings in Blast Injuries

Wounds resulting from high-velocity missiles and shotgun blasts are among the most severe wounds encountered in civilian practice. Extensive tissue destruction is incurred locally, with loss or disruption of the wound parts to form a cavity. Sites distant from the point of impact may be injured as a result of shock waves transmitted through tissues. The extent of injury of these complex wounds is difficult to assess.

Treatment of Blast Injuries

Initial care is directed at hemostasis, cleansing, and minimal debridement. It is wise not to close the wound primarily.

Repeated staged exploration at first presentation and then again 24 hours and 48 hours apart is used to remove necrotic or devitalized tissues. Antibiotic prophylaxis is recommended. Cefazolin, 1 g intravenously every 8 hours, is satisfactory. The wound is then closed secondarily, with priority given to reestablishment of bony relationships, followed by soft tissue coverage.

Disposition

Hospitalize these patients for management.

High-Pressure Injection Injuries

General Considerations

High-pressure injection equipment is used in industry to force liquids such as paint, paint thinner, oil, or grease through a small nozzle under high pressure, sometimes at pressure exceeding several thousand psi. If the nozzle is held against or close to the skin, it is possible for the liquid stream to be injected through the skin and into the subcutaneous tissues.

Clinical Findings

These injuries have the potential for severe sequelae usually resulting from direct trauma and intense inflammation incited by the injected liquid. The edema that develops from the resulting inflammation can lead to increased tissue compartment pressures and may lead to compartment syndrome. The type of injected material and amount and pressure velocity will determine the degree of inflammation and severity of injury.

Patients with these types of injuries usually have small puncture wounds that are usually isolated to the extremities. Patients often present with pain out of proportion to the appearance of the wound and, if early, often with only minimal swelling. Because the material is injected at great force, the distance it can be injected into the tissues from injection site can be significant.

Treatment and Disposition

Carefully assess neurovascular function at the time of presentation and attempt appropriate pain control via parenteral analgesics. Avoid digital blocks because of the resulting increase in pressure. Parenteral antibiotics should also be initiated at first presentation, directed at normal skin flora (Staphylococcus and Streptococcus). Appropriate radiographs should be obtained because some materials are radiopaque and may demonstrate the extent of subcutaneous spread and may also show the presence of subcutaneous emphysema. Early consultation with a hand specialist or other surgical specialist for early surgical debridement and follow-up is recommended.

Degloving Injuries

Clinical Findings

Separation of the skin and subcutaneous tissues from the underlying musculofascial planes constitutes a degloving injury. For flaps attached by a pedicle, the determinant of survival is their circulation.

Treatment and Disposition

All but trivial degloving injuries require hospitalization and plastic surgical consultation is advisable.

Amputations

Amputations of extremities and digits require careful prehospital care. The viability of the amputated part will depend on the degree of tissue damage, amount of ischemic time, and the ambient temperature. Reimplantation is usually possible with less than 6 hours of warm ischemic time. Cooler temperatures will prolong this window and cooling the amputated part correctly can extend this time to 24 hours in some instances. First responders should be trained to locate amputated parts, clean the parts with normal saline, and to wrap the part in saline-moistened (not wet) gauze. The part should then be placed in a waterproof plastic bag and the bag placed on ice for transport to the hospital. Amputated parts should never be placed directly into water or saline baths or in direct contact with ice. “Dry” ice should never be used to cool amputated parts as freezing of the tissue will occur.

The level of the amputation will affect the surgeon's decision to attempt reimplantation; physician-to-physician discussions are mandatory prior to transfer to a reimplantation center.

Bites

Most nonprimate mammalian bite wounds are minor, and only about 10% require suturing. The rare patient with major injuries sustained in an animal attack should be evaluated and receive treatment as any other patient with severe trauma.

Meticulous wound care is the cornerstone of therapy for bite wounds and is the most important factor in preventing infection. The wound should be cleansed, debrided, and copiously irrigated. Treat all bite wounds on the extremities aggressively, with antibiotics and elevation and immobilization of the affected part.

Routine cultures in the absence of infection need not be obtained, because there is no useful correlation between positive cultures and wounds that later develop clinical signs of infection. Antimicrobial prophylaxis (see Table 30–2) is recommended for all human and most cat bites but only for high-risk dog bites (below). The need for tetanus and rabies prophylaxis (Tables 30–3 and 30–4) should also be evaluated.

Dog Bites

Dog bites cause open wounds, often with tissue necrosis secondary to crush injury. Treat by prompt excisional debridement within 6 hours. If the extent of the wound or the length of time since injury precludes primary closure, the wounds should be irrigated, debrided, and left open or loosely sutured. Infection is unusual, and antimicrobial prophylaxis is not indicated in routine cases.

Dog bites associated with a high risk of infection are those of the hand, puncture wounds, and injuries more than 6–12 hours old. These wounds should be treated with vigorous local care and left unsutured. Antibiotic prophylaxis is recommended (Table 30–2). Low-risk bites do not require prophylactic antibiotics and may be sutured after appropriate wound care. Hospitalization is rarely indicated unless injuries are multiple or extensive or infection is present.

Infected bites should be cleansed and debrided and the affected limb immobilized and elevated. A parenteral dose of a first-generation cephalosporin should be administered in the emergency department and the patient discharged with oral antibiotics (same as those for prophylaxis, above) for 7–10 days. Patients should receive follow-up care within 1–2 days and be instructed to return earlier if their condition worsens. Hospitalize patients who have symptoms of sepsis.

Alcoholic patients and immunocompromised patients are at risk from rapidly overwhelming sepsis due to Capnocytophaga canimorsus after even minor dog bites.

Cat Bites

Cat bites cause deep puncture wounds with little crush injury and are associated with a high risk of infection, mainly with Pasteurella multocida. Wounds caused by cat claws are considered equivalent to bites. Treatment includes local cleansing, debridement, and prophylactic antibiotics for all significant bites. (Table 30–2).

Cat bite infections occurring within 24 hours are due to P. multocida and should be treated as mentioned above. Wounds becoming infected after 24 hours should be treated with a first-generation cephalosporin or amoxicillin/clavulante (see Dog Bites, above) for 7–10 days.

Hospitalization is rarely indicated unless infection is severe or involves the hand. Primary closure should not be performed except in low risk, cosmetically disfiguring facial bites.

Human Bites

General Considerations

Adult human bites are more serious than dog or cat bites. They are characterized by crush and tear injuries and are commonly located over the knuckles or the dorsum of the hand, frequently involving the tendons or joints. Inoculation of large numbers of bacteria from dental plaque also occurs. (Bites by children appear to carry a low risk of infection because of fewer mouth bacteria and less biting force.) Despite their rather innocuous initial appearance, these wounds are extremely dangerous, because they are prone to severe necrotizing infection.

Treatment and Disposition

Hospitalize patients with suspected tendon, joint, or cartilage involvement (eg, bites of the hand or ear) for vigorous irrigation, debridement, and parenteral antimicrobials (high-dose penicillin or clindamycin). Wounds of this type are never closed. Bites of other structures may be treated with vigorous irrigation and debridement in the emergency department, followed by antimicrobial prophylaxis (see Table 30–2). The injured part should be elevated, immobilized, and checked frequently to assess the possible spread of infection. The patient should be reexamined within 6–18 hours and subsequently at 1–2-day intervals for a week.

Signs of necrotizing infection are progressive erythema, blistering, and frank necrosis. If these signs are already present at the time of initial evaluation, hospitalization is indicated for wide debridement of the involved parts and parenteral antimicrobial therapy.

Puncture Wounds

General Considerations

Puncture wounds are at risk of becoming infected, especially if dirty, contaminated, or containing foreign materials. Wounds associated with penetration through the soles of shoes (especially sneakers) often contain particulate debris and are particularly susceptible to infection. If joint capsule or bone is penetrated, septic arthritis and osteomyelitis can occur. Pseudomonas species are common pathogens.

All puncture wounds should be probed gently with forceps or a long (6.5 cm or 2.5 in), 22-gauge needle for the presence of foreign bodies; control pain as needed with 1% lidocaine anesthetic. Obtain soft-tissue X-rays of all wounds for which the history or mechanism of injury suggests retention of a foreign body (eg, broken glass and flying piece of metal), even if results of the wound probe are negative.

Treatment and Disposition

Wound Cleansing and Exploration

Irrigate the wound with normal saline under pressure and cleanse it with 1% povidone-iodine solution. Probe gently and remove foreign materials. Local infiltration with 1% lidocaine and slight enlargement of the wound may be necessary for adequate exploration. Extensive dissection in the emergency department to search for small or deeply embedded objects is not recommended.

Tetanus and Antibiotics Prophylaxis

Ensure that tetanus prophylaxis is up to date (see Table 30–3). Treat dirty or deep wounds, especially those with possible joint or bone involvement, with prophylactic antibiotics (Table 30–2). If penetration occurred through the sole of a sneaker (unless very superficial), consider prophylaxis against the high risk of Pseudomonas infection with antipseudomonal cephalosporin as a single parenteral dose (eg, ceftazidime, 1 g intramuscularly) or ciprofloxacin 500 mg BID for 3–5 days.

Elevation and Follow-Up

Instruct patients to elevate any involved extremity and, in foot injuries, to bear no weight for 3–5 days. Except in the case of superficial punctures, patients should be reexamined in 5–7 days or earlier if increased pain, redness, red streaking, or pus is noted.

Osteomyelitis

Patients with pain persisting longer than 5–7 days or with an abnormal erythrocyte sedimentation rate may have osteomyelitis. In either case, obtain X-rays of the affected area and, if normal, consider referral for limited bone scan of the area. Refer patients with osteomyelitis to the specialist appropriate to the area of involvement.

Retained Foreign Bodies

Retained foreign bodies in critical areas (eg, eye) require urgent specialty consultation. Refer patients with possible retained foreign bodies in noncritical areas for outpatient surgical removal in 2–3 weeks.