Types of Wounds and Definitions

Abrasions result from tangential (shearing) forces. Although abrasions are most commonly superficial, they can be extensive and involve deep tissues. Superficial abrasions pose no threat to the patient but may require use of analgesics. Deep abrasions that have completely obliterated skin and denuded underlying fascia are at increased risk for infection and must be kept clean. By virtue of the mechanism of injury, abrasions involve more surface area than they do depth. As a consequence, they are not amenable to suture closure. Abrasions are treated by extensive irrigation to remove all debris (often dirt or gravel) and application of nonadherent dressings. Topical antiseptic solutions are not necessary but are useful adjuncts in preventing gauze dressings from adhering to raw tissue. Such dressings should be changed once daily or more frequently as needed for soiling or adherence (“drying out”). Abrasions do not form abscesses because they have no deep spaces to contain infection. They may become superinfected and develop cellulitis; although this is generally rare, the possibility is more real in the exposed wilderness environment. Diagnosis and management of cellulitis are discussed later in this chapter.

Burns (see Chapter 13) may result from thermal or chemical insults. These injuries span a spectrum from trivial sunburn to deep tissue necrosis. The first principle of management is to limit further injury by extinguishing the source, seeking shade, washing out chemicals, and so on. For chemical exposures, voluminous irrigation is the key to limiting further injury. This should be done with clean (not necessarily sterile) water, and the run-off irrigant should be prevented from injuring more skin.^7,^15,³⁴ Chemical quenchers (i.e., alkaline solution for an acid burn) should never be used because the resulting exothermic reaction will cause secondary injury. Once the burning process is arrested, burn care must focus on antisepsis because infection poses the single most important immediate threat.

Burn wounds should be fastidiously cleaned to remove all foreign material and devitalized skin. Depth was formerly described as first, second, or third degree, but modern description relies on the descriptors partial thickness and full thickness (Figure 22-1). Blisters should be left intact unless they interfere with function. There is some debate about the management of blisters, but in a wilderness environment, the “biologic bandage” provided by an intact blister supersedes any academic debate about the presence of inflammatory mediators in the blister fluid. Blisters over the palms or joints are exceptions to this rule, because their presence will significantly limit motion and potentially engender contraction or decrement in function. One school of thought is that these blisters should be unroofed and gently scrubbed away with a moistened gauze or trimmed with scissors. Once cleaned, burns should be dressed and kept clean. Topical antiseptic agents should be applied to burns with invasion deep enough to result in blistering or erosion through the skin to white tissue or burned muscle underneath. Silver sulfadiazine is an excellent agent, and can be reapplied once or twice daily to prevent the wound from desiccating. In the absence of silver sulfadiazine (and for burns <1% of body surface area), antibiotic or antiseptic ointment (e.g., bacitracin), can be employed.

FIGURE 22-1 Campfire burns, mostly partial thickness with both intact and ruptured blisters. The distal forearm is pale white without capillary refill, representing full-thickness injury.

(Courtesy Ramin Jamshidi, MD.)

Lacerations can be deep or superficial, simple or irregular (Figure 22-2). Generally, lacerations are amenable to primary repair (i.e., closure at the time of injury). Closure simplifies wound care and optimizes cosmetic outcome. Much of the following discussion is dedicated to management of lacerations.

FIGURE 22-2 A deep and irregular laceration that is suitable for irrigation and multi-layer closure with interrupted mattress sutures (see text).

(Courtesy Ramin Jamshidi, MD.)

Punctures are lacerations with very small entry site injury, but extended depth. Generally these injuries should not be closed because they cannot be adequately cleansed. There is little cosmetic benefit to closure, whereas there is significant risk for trapping infectious agents deep within them because of the inherent difficulty of properly irrigating the tract.

Clinical Presentation

Immediate evaluation of traumatic wounds should include determination of the type of injury. Focused assessment includes determination of surface area and apparent depth. Distal sensation and passive and active range of motion must be assessed to elucidate any associated nerve injury, tendon disruption, or fracture. Nerve and tendon injuries will not affect acute management but are important as a baseline examination. Fractures require immobilization, which is discussed in Chapter 27. Distal perfusion must be assessed to determine likelihood of vascular injury. If there is suspicion of vascular injury based on examination, depth of the wound, or blood at the scene, the wound should not be probed (nor blood clots dislodged) until one is prepared to place direct pressure to control hemorrhage and potentially ligate or suture the injured vessel.

Time since injury is very important when considering wound closure. Within several hours of injury, traumatic wounds become colonized with bacteria. Even without frank infection, heavy colonization impedes proper wound healing.^17,^23,⁴⁵ A bacteria-laden wound that has its edges approximated will generally not heal and has increased risk for developing an abscess. Various investigators have tried to establish a firm time limit beyond which traumatic wounds should not be closed, but results are inconsistent.^3,^28,⁴⁹

With copious irrigation and removal of foreign bodies, most wounds that are otherwise suitable for closure (see earlier discussion) can be closed if this is accomplished within 6 hours of injury.²¹ This deadline may be extended in the hospital setting, where thorough sharp debridement can be undertaken and the environment controlled. In some circumstances, wounds may even be closed days or even weeks after initially generated, but this involves sophisticated surgical care.²⁹ This situation should not be confused with an acute wound in the wilderness, which in all circumstances should be thoroughly irrigated, foreign bodies removed, and dressings applied. Acute wounds in the wilderness should be closed only if they are clean, suitable materials and instruments are at hand, and less than 6 hours have passed since the injury.

Treatment

Personal protective equipment should be donned before interrogating, preparing, possibly closing, and dressing a wound. Eye shields and gloves are considered mandatory equipment. Eye shields are particularly important in preventing exposure of mucous membranes to bodily fluids. Gloves are essential and should be made of a nonlatex material and contain no talcum or other lubricant. Talcum, calcium carbonate, and cornstarch are common glove lubricants, and all have been shown to cause wound granulomas, foreign body reactions, adhesions, and chronic sinuses. Sterile gloves are less cumbersome to work with but are not required because they do not reduce the incidence of infection in an austere setting.³⁷ Use of a mask has also not been demonstrated to reduce rates of acute wound infection but certainly provides a protective barrier for the care provider. Hair coverings are not necessary, because studies have failed to demonstrate reduction in wound infection rates.

Cleansing Techniques

Cleansing involves removing devitalized tissue, clearing debris, and copiously irrigating the area.²¹ This may involve vigorous manipulation of painful and sensitive tissues, so if oral analgesics are available, they should be used. Constricting jewelry and equipment should be removed from the affected area (e.g., rings, piercings). Ideally, hair around the wound is trimmed because the roots harbor bacteria. Hair should be trimmed to a few millimeters in height because shaving at the surface increases wound infection rates by causing superficial skin trauma.² Eyebrow hair is an important exception, because trimming or shaving can result in permanent abnormal hair growth. If hair trimming is not possible, an antiseptic ointment can be used to paste the hair down away from the wound.

Water should be used to clean the wound. There is no demonstrated benefit to use of saline solutions, and there is no absolute need for the irrigant to be sterile.^7,^15,³⁴ Although some persons mention use of dilute (1%) povidone-iodine as an irrigant, this is not proved to be more efficacious. Whatever method is available to generate potable water (e.g., iodine tablets, mechanical filter, irradiation, boiling) is sufficient to generate irrigation fluid for wound care. Hydrogen peroxide is injurious to deep tissues and should not be used as an irrigant.

The greatest impact on wound cleanliness is gained from volume of irrigant and simple mechanical debridement. Debridement is achieved by removal of obvious foreign material (as with forceps) and also by pulsing irrigant at the wound (the fluid agitation is an effective debrider) (Figure 22-3).³⁰ The available volume should be used in successive bursts rather than a single “gush,” because dilution of wound contaminants is far superior with small serial volumes. Although the matter has not been systematically researched, a guideline that is often used is a minimum of 100 mL per centimeter of wound length. Optimal stream pressure has been determined to be 5 to 10 psi, but in a remote setting, use of pressure gauges or regulators is unnecessarily cumbersome; it is sufficient to realize that excessive pressures are not required.^43,⁴⁹ A large (20 to 60 mL) syringe attached to a 19- or 20-gauge needle or catheter is an effective instrument for this purpose. Alternatively, holes can be punched into the cap of a squeezable water bottle to generate the same effect. A splash shield at the tip of the instrument decreases personal exposure risk. If not available as a specific commercial product for this purpose, one can easily be fashioned from a paper or plastic plate, or base of a disposable water bottle or drinking cup.

FIGURE 22-3 A, Irrigation of a deep inguinal wound to remove debris. B, Placement of an interrupted vertical mattress suture to approximate the deep tissue defect with eversion of the edge and relief of tension. C, Completed interrupted closure.

(Courtesy Ramin Jamshidi, MD.)

Preparing for the actual wound closure, the skin edges may be prepared with an iodine, povidone-iodine, chlorhexidine, hydrogen peroxide, or isopropyl alcohol solution, but these antiseptic agents should not be used within the wound itself because of potential toxicity. If concentrated ethyl alcohol (i.e., liquor) is available, it may be effective in reducing wound contamination, but this has not been systematically evaluated. These agents should be used to cleanse the skin surrounding the wound, using a gauze soaked with the liquid to paint an overlapping spiral from the wound outward to a distance of approximately 5 cm. The cleansed skin must be allowed to dry to achieve full effect; this takes 3 to 5 minutes at 20° C (68° F). Honey instilled into a wound has demonstrated certain antimicrobial properties, but conflicting research exists on this topic. Although it is recommended by some as an improvisational technique, it cannot be recommended as a routine adjunct at this time.

Vascular Injuries

Evaluation of hemorrhage is a major component of acute wound management; even if bleeding has stopped, there may be a risk for delayed rebleeding. The wound should be irrigated vigorously so that if bleeding is to occur, it happens while the wound is being interrogated and one is poised to address it. Inadequate hemostasis during initial treatment engenders avoidable delayed blood loss.

Bleeding from wounds can almost always be controlled with direct pressure. The most common reason for failure of direct pressure to control bleeding is too short a compression time. Initial pressure should be applied for 5 minutes (checked with a timepiece to ensure accurate timing). If bleeding persists, either pressure should be reapplied for 10 minutes, or pressure should be applied at both the wound and a proximal inflow point (e.g., popliteal, femoral, or brachial artery).²⁴ The second most common reason for failure of direct pressure is that pressure is not applied in a focused manner over the site of bleeding. A broadly applied towel over a large wound will not be as effective at controlling bleeding as will finger-point pressure applied over the actual site of greatest bleeding.

In the face of profuse diffuse bleeding (as from a large raw wound), topical adjuncts are available to promote thrombosis.⁴ QuikClot is a granular coagulant that was originally designed to be poured onto wounds to stop diffuse bleeding. The mechanism of action of the original product is adsorption of water onto zeolites, which activates factor XII and catalyzes platelet aggregation. However, the granule form of this material is difficult to use for two reasons: the poured material is unwieldy and difficult to control in windy situations; and the reaction is exothermic, causing pain and risking burn injury. QuikClot has now been modified and integrated into a gauze dressing (also marketed as Combat Gauze). The active element is now kaolin, an alumina silicate that activates and accelerates the enzymatic clotting cascade. The solid consistency of Combat Gauze is more manageable and generates no heat on application. Celox gauze is based on chitosan, a natural product derived from shellfish. Initial versions of this product were granules to be poured into a wound, but it is now embedded into an actual gauze dressing and also has no exothermic properties. HemCon bandages are also chitosan based and not exothermic. These agents are all designed to be applied directly to bleeding wounds and compressed with direct pressure. Before wound closure, these dressings must be removed and bulky gelatinous deposits in the wound irrigated out (although mild residual coatings are reportedly safe to leave in place). All of these agents are supported by anecdotal reports of success and are clearly superior to simple gauze dressings, reducing bleeding by nearly an order of magnitude. However, head-to-head studies published to date have been underpowered and are difficult to interpret. Ongoing development of these products and comparative evaluation are the most active areas of acute wound care research and development.

In contrast to the above products, which are designed to control gross hemorrhage, there are adjuncts intended to assist with lower volume bleeding within the wound. Surgicel products are procoagulant materials composed of a scaffold of cellulose polymer. They have been in clinical use for more than 60 years and are manufactured in fibrillar consistency as well as woven sheets. The major benefit of these agents is that they are totally absorbable, so they can be left on or within the wound, even suturing the wound closed over them. Gelitacel is a procoagulant dressing that is similar to Surgicel. It is a knitted sheet of resorbable cellulose that boasts complete dissolution in as short as 96 hours (more rapidly than Surgicel, thus theoretically less likely to result in an encapsulated collection within the wound).

Tourniquets may be considered as a last resort to stop life-threatening hemorrhage. Great debate exists over the use of tourniquets and who should be allowed to apply them (laypersons, emergency first responders, midlevel health care providers, physicians, or even specialty-specific physicians). The more proximal a tourniquet is applied, the greater the risk for devastating tissue/limb loss. The best potential use of a tourniquet may be for a traumatic amputation in which there is copious diffuse bleeding at the open end. In this case, a tourniquet can be firmly applied just proximal to the open wound so that little distal ischemic tissue is created (Figure 22-4). Commercial tourniquets such as the Combat Action Tourniquet are available, but a blood pressure cuff is often an effective instrument. Whatever device is employed, it should be applied and intensified until pressure exceeds arterial pressure and then increased at least another 20 mm Hg or until bleeding stops. If transport to advanced surgical care is expected to be prolonged (more than 1 hour), the tourniquet should be slowly released every 45 to 60 minutes and allowed to gently bleed (i.e., so long as bleeding is not torrential) for 3 to 5 minutes. This allows intermittent perfusion of tissue and can gradually induce ischemic conditioning of the affected tissue to lessen the effects of ischemia and reperfusion. However, this is controversial, and some authorities do not advocate intermittent loosening to avoid dangerous hemorrhage. When a tourniquet is released, it should be done slowly over a minute or two, because recirculation of stagnant, acidic, and hyperkalemic blood from the nonperfused distal limb can lead to hemodynamic instability. If dysrhythmia is noted, the tourniquet should not be released further until the patient stabilizes. Hypotension and even cardiac arrest may result when a tourniquet is released; these dangers are frequently overlooked and can cause tragic outcomes.

FIGURE 22-4 Severe complex crush injuries of both legs. These wounds mandate immediate evacuation, but profound hemorrhage may require tourniquet placement to prevent exsanguination until advanced surgical care is available.

(Courtesy Ramin Jamshidi, MD.)

Although profuse external hemorrhage is easy to localize, ischemic complications of vascular injuries are more subtle and sometimes overlooked. Examination findings are classically divided into “soft” and “hard” signs of vascular trauma, indicating the relative likelihood of a significant vascular injury (Table 22-1).²⁴ Presence of a hard sign is more than 90% predictive of need for vascular intervention. Only about one-third of patients with a single soft sign have an abnormality on arteriography, and few of these require emergent intervention. Any patient with a hard sign of vascular injury requires immediate evaluation by a surgeon.

TABLE 22-1 Relative Indicators of Vascular Injury

“Hard Signs”	“Soft Signs”
Active or pulsatile hemorrhage Pulsatile or expanding hematoma New thrill or bruit Limb ischemia/compartment syndrome Diminished/absent distal pulse	Hypotension/shock Neurologic deficit immediately following injury Stable, small, nonpulsatile hematoma Proximity of wound to major vessels

Anesthesia

Manipulation of traumatic wounds can be painful and anxiety provoking. Studies have demonstrated that music can reduce procedural anxiety.^32,⁴² For most patients, explaining the steps involved can improve tolerance by guiding expectations.⁵⁴ If vigorous debridement or suture closure is to be attempted, infiltration of local anesthetic can provide tremendous comfort for the patient and thus facilitate technically superior closure. Anesthetic solutions can be applied locally within tissue, as topical agents, or as regional nerve blocks.

Direct intradermal or subcutaneous injection is the most common technique of local anesthetic use. These agents are synthesized in two related chemical classes: aminoamides (lidocaine, bupivacaine, dibucaine, etidocaine, mepivacaine, prilocaine, and ropivacaine) and aminoesters (chloroprocaine, procaine, tetracaine, and cocaine ). Characteristics of the most commonly used local agents are listed in Table 22-2. Inclusion of epinephrine in the solution effects local vasoconstriction by α₁-adrenoceptor agonism and nearly doubles the duration of the local effect of the medication. By slowing systemic absorption of the anesthetic, it also increases the maximum allowable total dose. Inclusion of epinephrine in the anesthetic solution is believed by some to improve local hemostasis, but this is a minor contribution relative to the effect of increased tissue turgor from infiltration of the solution. Conventional teaching is that epinephrine-containing local anesthetic solutions should not be used in end-vascular beds such as the nose, fingers, toes, and penis because of concern for ischemia. However, there is literature to support safe use of these solutions for digital blocks.^46,⁵¹ Using anesthetics without epinephrine allows maximum flexibility in terms of allowable location of use. Pain of injection for any local anesthetic can be attenuated by mixing 1 mEq of sodium bicarbonate with each 9 mL of anesthetic to buffer the solution. It should be noted that this delays the onset of action by approximately 5 minutes.

TABLE 22-2 Properties of Select Local Anesthetics