Authors: Anthony D. Dake, MD, Chief Resident,Department of Emergency Medicine, Vanderbilt University Medical Center, Nashville, TN.
Larry Stack, MD, FACEP, Director of Emergency Department Operations, Assistant Professor of Emergency Medicine, Vanderbilt University Medical Center, Nashville, TN.
Peer Reviewers: David Kramer, MD, FACEP, Associate Professor, Program Director, Division of Emergency Medicine, Emory University School of Medicine, Atlanta, GA.
Jeffrey Jones, MD, FACEP, Assistant Professor and Research Director, Department of Emergency Medicine, Butterworth Hospital, Michigan State University College of Medicine, Grand Rapids, MI.
It is predicted that by the year 2003 firearm-related injuries will be the leading cause of death in persons between 1-44 years of age.1 This disturbing projection is based upon documentation of a trend beginning in 1968 and continuing through 1991, during which firearm-related deaths increased by 60% and accounted for an alarming 38,317 deaths by 1991.1 The morbidity and mortality associated with penetrating trauma are more extensive than these statistics might suggest. For every fatal firearm injury, there are two additional, nonfatal injuries requiring hospitalization, as well as 5.4 nonfatal injuries of insufficient severity to require hospitalization.2 The majority of nonfatal injuries caused by firearms involve the extremities. Because nearly all patients with penetrating injuries to the extremities will present to an ED for acute care, emergency physicians must be able to characterize the precise nature and extent of these injuries and implement appropriate treatment when indicated. In addition to assessing and managing firearm injuries, which include gunshot wounds (GSWs) and shotgun wounds (SGWs), practitioners must be equally proficient at the evaluation and treatment of stab wounds (SWs). With these clinical entities in mind, this article presents a systematic approach to the management of penetrating extremity trauma (PET) associated with firearm injuries and stab wounds.
The Editor
Precise and clinically effective evaluation of PET requires the clinician to understand the anatomical boundaries of the upper and lower extremities as defined by the trauma literature. Wounds that lie outside these boundaries are more likely to reflect life-threatening injuries involving vital organs and, therefore, should not be evaluated in the manner outlined in this review.
Upper Extremity. The upper extremity (UE) begins at the deltopectoral groove and extends distally. Major vessels of the UE include the axillary, brachial, radial, and ulnar arteries. (See Figure 1.) The axillary artery begins at the lateral border of the first rib and continues until it becomes the brachial artery at the inferior border of the teres major muscle. A few centimeters below the antecubital fossa, the brachial artery gives rise to the radial and ulnar arteries, which both continue into the hand, where they divide into smaller branches.
Lower Extremity. The lower extremity (LE) begins at the inguinal ligament anteriorly and at the inferior gluteal fold posteriorly. Major vessels include the femoral, popliteal, posterior tibial, anterior tibial, and peroneal arteries. (See Figure 2.) The femoral artery enters the LE inferior to the inguinal ligament midway between the anterior superior iliac spine and the pubic symphysis. It courses medially and posteriorly as it descends, passing through the adductor canal. The popliteal artery represents the continuation of the femoral artery as it passes through the lower border of the adductor canal. It descends through the popliteal space between the femoral condyles and terminates at the lower border of the popliteus muscle by dividing into the anterior tibial and posterior tibial arteries. The peroneal artery arises from the posterior tibial artery about 2-3 cm distally.
This region gives rise to major arteries of the lower leg commonly referred to as the trifurcation. The posterior tibial artery descends in the deep posterior compartment before passing behind the medial malleolus and entering the foot. The peroneal artery descends near the fibula ending at the ankle, where it produces collaterals to the anterior and posterior tibial arteries. The anterior tibial artery passes forward into the anterior compartment and descends on the interosseous membrane before terminating at the ankle by becoming the dorsalis pedis artery.
Wound Ballistics: Predicting Tissue Injury
A clinically relevant understanding of wound ballisticsthe study of a missile’s effect on living tissueis mandatory in order to perform a targeted physical assessment and to institute appropriate treatment options.3 Generally speaking, factors that determine a missile’s ability to injure tissue include the missile’s mass and velocity, the missile’s physical specifications, and characteristics of the tissue that has been penetrated.
Velocity, Cavitation, and Secondary Missiles. In the past, disproportionate emphasis was placed on the missile’s velocity. "High-velocity" missiles, which were usually defined as those with a muzzle velocity greater than 2500 ft/s, were believed to have the greatest wounding potential because of a phenomenon called "temporary cavitation." 3,4 Two types of cavities are formed when a missile strikes tissue. (See Figure 3.) The permanent cavity is the direct track taken by the missile. This cavity is formed as the missile crushes tissue in its path and impels surrounding tissue centrifugally.5 The temporary cavity, which surrounds the permanent cavity, is formed as tissue is displaced by a pressure wave that accelerates radially from the missile, similar to a splash.4 Because of temporary cavitation, bullets are able to produce tissue injuries that are distant from the permanent cavity. The extent of damage is variable. For example, blood vessels within the temporary cavity are occasionally disrupted or severed, and broken bones are rare.5 While it is true that high-velocity missiles cause large temporary cavities, lower velocity missiles that flatten or deform also can cause large temporary cavities. The older ballistics literature overstates the importance of velocity on temporary cavitation and fails to consider the importance of missile and tissue characteristics.
In this regard, bullets that change their orientation in tissue ("tumble" or "yaw") or change shape ("deform") cause more tissue destruction than those that do not.4 For example, a hollow or soft-point bullet that deforms upon striking tissue will cause more damage than one with a full metal jacket that does not deform. Bullet fragmentation is even more devastating to tissue. With fragmentation, a missile breaks apart within the tissue, creating many smaller projectiles. (See Figure 4.) As a rule, bullet fragmentation causes more tissue disruption than yawing or temporary cavitation alone.6
The amount of damage produced by a penetrating projectile also depends upon the specific characteristics of the tissue that has been violated by the missile. For example, temporary cavitation produces more severe injuries in poorly elastic tissue, such as liver, than in more pliable tissues, such as muscle.4 It should be emphasized that bone fragments produced by a missile strike may also behave as "secondary" projectiles, which have the capacity to cause significant tissue disruption.6 Articles of clothing struck by bullets prior to tissue penetration can cause bullet fragmentation and lead to increased tissue damage.
Wound Ballistics and Gun Range. There are many variables that determine SGW ballistics. Characteristics of the weapon, including gauge, barrel length, and choke play a role, as do ammunition characteristics, such as shot size, powder load, and wadding type. Unfortunately, a discussion of each of these variables is beyond the scope of this monograph. Instead, this review will focus on the single most important variable in SGW ballistics: the distance between the weapon and the victim.
Because of their highly variable wound ballistics, shotgun injuries represent not only some of the most devastating and deadly wounds encountered in the ED, but also some of the most benign. At close range, shotgun injuries are characterized by massive tissue destruction, but at greater distances, they may consist of little more than a single subcutaneous pellet.9 Although the pellets are traveling at low velocity, their large mass imparts an extraordinary quantity of energy to the tissue, which produces massive tissue destruction.3,9,10 With greater distances, the pellets lose velocity and spread apart, with each pellet acting as a single missile. At a distance of less than seven yards, the pellets still retain enough velocity to cause marked tissue penetration. Characteristically, large wounds are produced first, because the pellets are spread over a large area, and second, because the individual pellets behave erratically in the body, following tissue planes rather than their original trajectory.3 At distances greater than seven yards, the individual pellets lack the velocity needed to penetrate beyond subcutaneous tissue and underlying fascia. Furthermore, the pellets continue to spread apart so that only a few may actually strike the target. The result is a superficial wound with fewer pellets.
Classification Scheme. A classification scheme has been developed in order to effectively communicate the distance-dependent features of SGW ballistics.8 Type I injuries are the result of "long-range" shots, (i.e., those initiated at a distance ³ 7 yards). As a rule, these missiles penetrate subcutaneous tissue and deep fascia only. Type II injuries are the result of shots fired at close range (3-7 yards), and these missiles usually perforate structures beneath the deep fascia, such as blood vessels and nerves. Type III injuries occur at point-blank range (< 3 yards) and are characterized by massive tissue destruction.
As might be expected, wound ballistics do not apply to stab wounds (SWs) because they are not caused by missiles. Nevertheless, their mechanism of injury deserves special mention. SWs are the result of direct tissue cutting. Tissue damage is predictable based on the inflicting instrument. Indirect tissue damage, such as that produced by temporary cavitation, is not seen with SWs.11,12
In summary, wound ballistics are complex and involve the interplay of missile velocity, bullet type, and tissue characteristics. Although the physician may not always know the type of weapon and ammunition involved, when this information is available, it will help the ED physician gain a better understanding of the potential injuries and complications. When information about the missile is not available, clues from physical and radiographic examination may be clinically helpful. For example, when fragmentation is seen on x-ray, a large amount of tissue disruption should be suspected. These findings can then be used to guide clinical decisions involving wound debridement and antibiotic administration.
The initial management of patients with PET should proceed according to Advanced Trauma Life Support (ATLS) guidelines. The primary and secondary survey should focus on identifying and treating life-threatening injuries. For patients who have sustained PET, this usually means identifying sites of major hemorrhage and managing these injuries with the direct application of pressure. For patients who are unstable as a result of hemorrhagic sequelae, immediate surgical exploration is indicated. In stable patients, the clinician should perform a detailed physical examination and use selected radiographic procedures in order to identify any associated neurovascular or skeletal injuries. As the evaluation is proceeding, appropriate pain control and tetanus prophylaxis are mandatory. The physical exam should focus on characteristics of the wound, neurovascular status, and skeletal integrity. Initial radiographic exam includes anterior-posterior and lateral films extending to a joint above and below the injury. The radiographs should be evaluated for the presence of bony injury and foreign bodies. If vascular, skeletal, and/or neurologic injury are present or suspected, the emergency physician should proceed with strategies, assessment techniques, and management protocols outlined in the following sections. If no associated injuries are detected, wound management guidelines are indicated.
Peripheral Vascular Injury: Evaluation and Management Strategies
Confirming or excluding vascular injury is one of the principal goals in the evaluation of patients with PET. In particular, arterial injuries require prompt recognition and treatment in order to prevent loss of life or limb. The following discussion of arterial disruption is applicable only to injuries of the proximal UE and LE, which include major arteries of the UE and LE extending to the level of the mid-forearm and mid-lower leg, respectively. Because tissue structures distal to these arteries have abundant collateral blood flow, operative exploration and repair are rarely required for injuries in this area. Most venous injuries do not require operative repair. However, thromboembolitic complications have been seen with femoral popliteal vein injuries.
Types of Arterial Injury and Complications. Precise evaluation of an extremity with a penetrating wound requires a thorough understanding of the various types of arterial injuries that can result, their clinical manifestations, and possible complications. (See Figure 5.) Lacerations of the vessel wall are probably the most significant type of arterial injury, ranging from small defects to complete transections with loss of vessel continuity,. Life-threatening hemorrhage or exsanguination may result from severe lacerations. On occasion, however, the severed ends of the vessel will retract and thrombose. An arteriovenous fistula may form when an artery and vein have contiguous injuries. In some cases, this complication can cause high-output cardiac failure as well as chronic arterial or venous insufficiency. Missiles can also cause aneurysmal dilatation of an artery, which results from stretching and thinning of all layers in the vessel wall. A pseudoaneurysm is formed when the intima, or inner portion of an artery, balloons out through a defect in the adventitia, or outer portion of the vessel wall. Aneurysms and pseudoaneurysms may compress adjacent structures. In addition, they often contain thrombus, which can embolize to distal structures. Occasionally, the only injury to the vessel may be an intimal defect. These injuries are a nidus for thrombus formation that can occlude the lumen or embolize distally. In some cases, the arterial wall will only sustain a contusion, which may be asymptomatic, produce transient spasm, or, occasionally, lead to thrombosis. Finally, external compression from bone shards or the offending missile can impede blood flow.
Clinical Manifestations. Generally speaking, clinical manifestations of arterial injury can be divided into two categories. The so-called "hard" signs strongly indicate or confirm arterial injury, and their presence necessitates urgent surgical exploration. (See Table 1.) In contrast, the "soft" signs only suggest arterial injury, and their presence should prompt surgical consultation and further diagnostic evaluation. (See Table 2.)
Pulsatile or exsanguinating hemorrhage is the most obvious hard sign confirming arterial injury. Definitive treatment is surgical exploration and repair. Temporizing measures include compression and clamping of visualized vessels using noncrushing vascular clamps. It should be stressed that blind clamping in open wounds should be avoided because this technique is associated with a significant risk of damaging other structures in the neurovascular bundle. A pulsatile or expanding hematoma may form when arterial bleeding is contained by surrounding tissue structures. This entity is designated a "false aneurysm," and its presence indicates a full-thickness arterial wall injury. Audible bruits and palpable thrills result from the disruption of normal laminar blood flow and may occur with nearly any type of vessel injury.
Another reliable hard sign of arterial injury is evidence of regional ischemia. Signs of ischemia can be remembered as the "six Ps": pulselessness, pallor, poikilothermia, paresthesia, paralysis, and pain. Paresthesias, paralysis, and pain are the result of altered conduction in ischemic nerve tissue. Pulselessness, pallor, and poikilothermia are the direct result of diminished blood flow to distal tissue. A palpable but diminished pulse is sometimes considered a soft sign, but will be a considered a hard sign for the purposes of this discussion. It should be noted that elderly patients may have preexisting diminished pulses secondary to peripheral vascular disease. Therefore, comparison should be made with the unaffected extremity. Conversely, a normal pulse does not exclude arterial injury, since almost 25% of patients with confirmed arterial injury will not have a pulse deficit.11,13
A moderate amount of hemorrhage at the scene is a soft sign that suggests arterial injury. Unfortunately, "moderate hemorrhage" is not defined in the literature, which makes this sign very subjective. The presence of so-called "moderate" hemorrhage may produce a confusing the clinical picture. In some cases, it may suggest a severe arterial injury that has become clinically less apparent due to tamponade or spasm by the time the patient is evaluated in the ED. Emergency medical systems (EMS) personnel can often provide important clues to help decipher the etiology of this physical finding. Small, nonpulsatile hematomas, as opposed to those that are pulsatile, do not require surgical exploration, but rather, should be treated in a fashion similar to other soft signs. Be aware that when one portion of the neurovascular bundle is disrupted, other portions may be injured as well. Consequently, an anatomically contiguous nerve deficit is strongly suggestive of arterial injury.
Unfortunately, much of the trauma literature on this subject is directed toward the treatment of wounds that are in "proximity" to major arteries but lack any of the previously mentioned signs.13-17 These wounds are said to manifest the soft sign of "proximity." As you might expect, proximity is a very subjective and somewhat vague term, even as it is described in the literature. In one study, for example, proximity was defined as any wound or missile track located within 1 cm of a major vessel.14 Other studies use different criteria, or fail to define proximity altogether. The fact that asymptomatic proximity wounds may have clinically occult arterial injury is well-known, regardless of whether the injury has been caused by a GSW, SGW, or SW.11,13-30 Currently, the most effective means of excluding arterial injury in proximity wounds is the subject of much debate.
Surgical Exploration and Evaluation. Techniques and guidelines for evaluation and treatment of vascular trauma have changed considerably over time. Most early experience with these injuries was encountered in the setting of military conflicts. For example, during World Wars I and II, extremity wounds that were in close proximity to major vessels were explored. Vascular injuries were ligated with subsequent amputation of the extremity. During the Korean and Vietnam Wars, surgical exploration of proximity wounds continued, but repair of injured arteries became more common as more advanced surgical techniques developed and antibiotics became available.25,31 Surgical exploration of all proximity wounds carried over into civilian practice until the early 1980s, when angiography was shown to be a reliable method for excluding arterial injury. Eventually, studies confirmed that exclusion arteriography was safer, more cost-effective, and just as reliable in characterizing the severity of vascular injury as surgical exploration.13
Exclusion Angiography. Currently, short of operative exploration, exclusion angiography (EA) is the "gold standard" for determining the presence of arterial injury. In this regard, it is the modality of choice for evaluation of large soft-tissue injuries such as SGWs.13,14,26 In addition, this technique may be used in patients with known arterial injury in order to plan for surgery.26,31 However, EA is no longer the initial diagnostic procedure choice in patients with soft signs. In these patients, arterial injury documented by EA is present in 9-23% of cases.19,26,32 By definition, injuries presenting with soft signs are nonocclusive and usually consist of small intimal defects, pseudoaneurysms, and focal narrowing caused by spasm. When these injuries are followed over time, they will require repair in less than 2% of cases.19,26,32 The benefits of detecting this small number of clinically significant injuries may be outweighed by the complication rate associated with EA. Minor complications, including hematoma, occur in 5% of patients under EA; whereas major complications, such as contrast reaction and thrombosis, can be expected in about 0.8% of cases.26 In addition, EA will produce false-positive results in up to 3.8% of cases, which can lead to unnecessary surgery.14 A false-positive EA is usually caused by arterial spasm, which is difficult to differentiate from thrombus. One further advantage to arteriography is the control of hemorrahage in extremities using embolization. The radiologist’s ability to approach an injury via the artery rather than through an area of hemorrhage would be especially appreciated by any surgeon who has ever tried to locate and control a bleeding vessel deep in the upper thigh. The unfavorable risk-benefit ratio in injuries associated with soft signs has induced many physicians to rely more heavily on the physical examination and on less invasive modalities to determine the need for surgical exploration.
Doppler Ultrasound. Not without its limitations, Doppler ultrasound (DU) offers many advantages over EA for evaluation of patients with soft signs of arterial injury. This technique permits the ED physician to delineate the architecture of vessel in multiple planes and to evaluate the direction as well as velocity of blood flow in real time. It is noninvasive, portable, and less expensive than EA. Doppler ultrasound also may be helpful for visualizing adjacent structures and may detect foreign bodies and venous injuries. Finally, serial exams can be performed in order to evaluate the progression of a lesion over time, without increased risk to the patient.
Unfortunately, there are some important disadvantages associated with DU. For one, it is often unavailable at night, when PET is most likely to occur. In addition, DU is operator dependent and requires that the technician and interpreter be experienced in its use. It is technically more difficult to perform DU evaluation of large soft-tissue defects, especially in cases characterized by a large quantity of soft-tissue air or hematoma.16,18 Finally, DU may miss injuries to aberrant arteries that track through a wound, such as branch vessels that originate more proximally than expected. To a great degree, this pitfall can be prevented by imaging arteries to a level that is at least one bifurcation above and below the injury site.16
Well-designed prospective studies comparing DU to the current gold standard of EA are sparse. However, the available data suggest that DU is effective in ruling out clinically significant arterial injury when used in the proper setting and patient population.15,16,18,20,21,23 In this regard, studies indicate that DU has a specificity of 99-100%, although sensitivity is more difficult to determine.15,16,18 When DU is followed by EA, its sensitivity ranges from 50-58%. However, injuries missed by DU and subsequently detected by EA, often did not require operative repair.16,23 Other studies using DU alone, without comparison to EA, have found it to have a sensitivity ranging from 83-100%.15,16,21 The higher sensitivity found in these studies probably reflects the fact that missed injuries (false negatives) never become clinically apparent and, therefore, were never entered into the calculation of test sensitivity. Despite concerns over research methodology, most authors agree that DU is an effective study in the hands of experienced ultrasonographers.15,16,18,20,21,23
Some authors suggest that physical exam alone may be sufficient to exclude significant arterial injury. As stated earlier, physical exam will miss 0-2% of all arterial injuries that eventually require repair.13,19,26,32 Patients in these studies were admitted and observed for at least 24 hours. If a noninvasive study is not available as part of the ED evaluation, admission and observation represent a reasonable alternative. The length of observation time required to exclude significant arterial injury has not been determined. In the future, observation units may be a cost-effective means of excluding significant arterial injury.
In summary, patients with hard signs should undergo immediate surgical exploration. (See Figure 6.) For patients with soft signs, there are several options worthy of consideration. When large soft-tissue defects are present, as in the case of SGWs, EA remains the modality of choice. In patients with uncomplicated wounds, DU can effectively exclude serious injury. If DU is unavailable, admission and serial physical exams, or a study at a later date, represent the most prudent course.
Careful physical examination and radiographic evaluation are required to confirm injuries to the bone and/or joint space. The frequency of these injuries should not be underestimated. Gunshot and shotgun wounds produce fractures in at least 23% of cases and may also result in joint space penetration.33 Because fractures caused by stab wounds are rare, they will not be addressed in this article. As a rule, detection of bony injury is usually not difficult, especially if bone fragments are protruding through soft-tissue defects or if gross instability of the affected extremity is present. Assessment of possible fractures is more problematic in the case of small cortical defects of the bone, in which case stability of the extremity usually is not affected. Similarly, joint space violation is easy to document if the articular surface is visible in a wound or if a large effusion is present. In many situations, however, violation of the joint space must be suspected based on missile trajectory alone. When a fracture or joint space violation is detected, early orthopedic consultation is recommended.34 In addition to patient stabilization, therapeutic interventions include antibiotic administration and immobilization of the affected extremity.
The type of antibiotic and its route of administration should be determined in conjunction with the consultant. A pre-established policy for guiding antimicrobial therapy is recommended. If guidelines are not available and a consultant is not immediately available, a broad-spectrum cephalosporin given intravenously is generally recommended. Whether intravenous antibiotics are required for all fractures is a subject of significant debate. In the past, all gunshot-induced fractures were treated with surgical debridement and intravenous antibiotics. This protocol was based on the military’s experience with wounds characterized by marked tissue devitalization and contamination. Today, however, most civilian GSWs are from low-velocity handguns, which do not produce significant amounts of devitalized tissue. Accordingly, a more conservative approach has been advocated.35,36 Debridement is less extensive and often done at the bedside. Intravenous antibiotics are still recommended, but may be given orally to selected patients.35-37 In contrast, fractures associated with shotgun blasts usually result in extensive soft-tissue damage and are often contaminated with wadding. Consequently, more extensive debridement and intravenous antibiotics are recommended.10,38
Extremities with suspected fractures should be immobilized in order to reduce pain and prevent any further soft-tissue or neurovascular damage. Immobilization may also restore blood flow to ischemic tissue by relieving pressure on arteries caused by bony fragments. These interventions often can be performed in the field by EMS personnel. There are many commercially available devices from which to choose. In addition, splints can be constructed from everyday materials. Although a discussion of splinting is beyond the scope of this article, a few concepts should be emphasized. Splints should be well-padded in order to avoid local skin necrosis, and they should allow for some expansion. Splints should be applied in a manner that immobilizes the joints immediately above and below the fracture. Finally, splints do not need to be removed upon arrival to the ED, unless they interfere with adequate physical examination or radiographic studies. In summary, initial treatment of PET associated with fractures or joint space violation includes immobilization, pain control, antibiotic administration, tetanus prophylaxis, and orthopedic consultation.
Although most peripheral nerve injuries (PNIs) are the result of blunt trauma, they may also be seen in the setting of PET. Because certain PNIs may benefit from early repair, their detection is mandatory to improve outcomes.39 PNIs, which may range from contusion to complete transection, are most likely to occur when there is an associated fracture. Missiles may injure the nerve directly, resulting in a partial or complete transection. Indirect missile injury from temporary cavitation may stretch or contuse the nerve. Stab wounds may result in partial or complete transection of peripheral nerves and may benefit the most from primary repair. In the case of missile wounds, the degree of nerve injury may be extremely difficult to assess on initial examination. For example, a contused nerve may initially demonstrate complete loss of function, but subsequently recover completely without intervention. For this reason, PNIs caused by missile injuries usually are not repaired primarily. PNIs resulting from bony injury will spontaneously resolve in 80% of patients.40 Regardless of the mechanism or degree of dysfunction, surgical consultation is recommended when PNI is present.34
Once neurovascular and skeletal injury have been excluded, the emergency physician can focus on specific issues related to wound management. A critical priority is deciding whether the wound can be treated in the ED or whether operative management indicated. This triage determination will depend upon the size of the wound, the degree of contamination, and the extent of devitalized tissue. Unfortunately, specific guidelines incorporating each of these factors into an equation for clinical management are not available. In general, however, if the ED physician is concerned that any one or more of these factors cannot be adequately addressed in the ED, then surgical consultation should be obtained. In this regard, attempting to manage complicated wounds without adequate lighting, anesthesia, and equipment may lead to inadequate debridement, retained foreign body, or wound hematoma.41 Additional strategies regarding wound irrigation, debridement, tissue repair, and antibiotic administration are discussed below. Without exception, however, all patients treated in the ED should have appropriate analgesia, tetanus prophylaxis, and detailed instructions for follow-up wound care.
Stab Wounds. Simple, superficial knife lacerations-which are longer than they are deepcan usually be repaired in the ED. These wounds should be irrigated with large volumes of an electrolyte solution, and all nonviable tissue or foreign material should be removed. Irrigation with antiseptic solution is discouraged because it is ineffective in killing bacteria in this setting and may damage the host defense mechanism.42 Once irrigation is completed, these wounds can be sutured. An exception to this approach applies to stab wounds that are more than six hours old at time of presentation. These wounds are at increased risk of infection, and the optimal approach to treatment is controversial. Generally, simple wounds without much contamination can probably be safely treated with primary closure, whereas more extensive wounds with a delayed presentation and that also appear to be contaminated should be left open to heal by secondary intention.41
It should be stressed that SWs are often deep and narrow and exhibit little more than small, external openings similar to puncture wounds. Irrigation is not recommended in these cases, because effectiveness is questionable and may cause damage to underlying structures.42 It should be noted, however, that there is not definitive consensus in this area, some experts do not recommend irrigation. Suturing should be avoided as it prevents the wound from adequately draining. A single dose of a parenteral antibiotic, with or without a course of oral antibiotics, is often administered, but the effectiveness of this practice has never been convincingly demonstrated.42 If an antibiotic is given, it should be administered by the parenteral route in order to achieve adequate tissue levels within four hours. In addition, it should have adequate gram-positive coverage. A first-generation cephalosporin or extended-spectrum penicillin is recommended.
In summary, therapy for soft-tissue stab wounds is conservative. Except in selected cases, suturing and irrigation are not recommended; antibiotic administration is controversial and is left to the discretion of the ED physician.
Gunshot Wounds. GSWs typically consist of a small entrance wound and a permanent cavity, with or without an exit wound. The missile may be lodged deep within the wound, and attempts to remove it should be avoided because of the risk of further injury or contamination. In the past, wide surgical excision of the wound tract was recommended. This practice was based on the military’s experience with high-velocity GSWs, which, it was thought, could produce marked tissue devitalization as a result of temporary cavitation.4,43
Recent clinical experience supports the notion that high-velocity missiles do not cause the degree of temporary cavitation once speculated, and what’s more, most civilian GSWs are caused by low-velocity missiles. As a result, experts now believe that wound excision is unnecessary.43 Even the common practices of irrigating and "coring" the skin edges of entry and exit wound sites have not been proven to reduce infection.42,44 Although antibiotics are usually administered, there are no controlled studies proving benefits in reducing risk of infection.42,45 Based on these findings, management of soft-tissue injuries associated with GSWs should adhere to the protocol outlined above for stab wounds.
In patients who have sustained Type II or Type III SGWs, surgical consultation is recommended. In addition, it is suggested for all but the most superficial Type I wounds. There are several factors supporting this approach. First, SGWs typically produce a large area of soft-tissue devitalization that will require surgical debridement in order to prevent infection.7,10 In addition, aggressive wound exploration is required to remove retained wadding that frequently leads to infection.10,37,38 Finally, fasciotomy is often necessary to address the marked soft-tissue edema typical of SGWs.10,38 When patients with superficial Type I wounds are discharged from the ED, adequate analgesia and follow-up for wound check must be assured.
Infection. One of the leading causes of morbidity from PET is infection. Microorganisms may be introduced into the wound from a number of sources. Contrary to popular dogma, bullets are not sterilized by firing.46-48 Moreover, bullets may acquire additional contaminants as they pass through clothing, skin, or a hollow viscus.46,47 Temporary cavitation creates a vacuum that can draw skin, clothing, or other contaminants into the wound from both entrance and exit wounds.46 Finally, shotgun wadding is an important contaminant known for producing a high rate of infection.7,38
If wounds become infected, they should be opened. Dressing changes should be applied until clean. Abscesses should be adequately drained. Antibiotic therapy is directed against gram-positive organisms, especially Staphylococcus species. First-generation cephalosporins and anti-staphylococcal penicillins are recommended.42
Lead Poisoning. A rare, but well-documented complication of retained missile fragments is lead intoxication.49,50 This delayed complication may present as anemia, abdominal colic, nephropathy, encephalopathy, or motor neuropathy. The clinical symptoms are slow to develop, with an average of 17 years for single bullet wounds and nine years for multiple fragments.50 Most patients will never develop lead poisoning, because the bullet is walled off by scar tissue and the lead is never made soluble. In patients who do develop lead toxicity, the majority have lead fragments in contact with synovial, bursal, or pseudocyst fluid. It is hypothesized that this fluid contains a factor that is able to dissolve the lead.49 Treatment of patients who have developed toxicity consists of chelation therapy followed by removal of the lead fragments. In asymptomatic patients who have lead fragments in contact with synovial or bursal tissue, surgery to remove the fragments may be indicated.49
Pediatric Considerations. In children, the risk of delayed diagnosis of a vascular injury is compounded by the prospect of a permanently short limb. Children readily develop collaterals around a segmental occlusion of a main artery; however, the collateral circulation never equals blood flow in the native artery, and continued reliance on it will inevitably slow the rate of growth of the extremity.
Compartment Syndrome. Compartment syndrome (CS) represents a state of increased pressure within a closed, nondistensible, osseofascial compartment resulting in compromised blood flow through nutrient capillaries to myoneural tissue. PET may lead to a compartment syndrome as the result of reperfusion injury that occurs postoperatively following restoration of arterial blood flow to ischemic tissue.25 Less frequently, PET may cause CS as a result of soft-tissue injury alone.51
The first symptom of a CS is often pain greater than expected for a given clinical situation. Other manifestations of CS include hypesthesia, weakness, pain with passive stretching of the muscle groups involved, and tenseness of the compartment. The presence of a distal pulse does not exclude the diagnosis. This is because the critical closing pressure of an artery is higher than the capillary perfusion pressure.52 The clinical presentation of CS can be summarized by the "six Ps": pain, pressure, pain with passive stretch, paresis, paresthesia, and present pulses.51 Note that these are different than the "six Ps" of arterial injury.
A CS in the setting of PET is a surgical emergency. Relief of compartmental pressure with fasciotomy is the definitive treatment.51,53
Discharge from the ED is possible in patients without evidence of neurovascular or skeletal injury who do not have large soft-tissue defects. This predominantly refers to patients with non-proximity injuries to the lateral thigh and lateral or posterior arm. Tetanus immunization, if not current, should be provided, as well as antibiotics if indicated. Patients should be instructed to return to the ED for symptoms of compartment syndrome or infection. They should have a follow-up appointment within two days to check for infection and neurovascular compromise.
The EP must be adept at evaluating patients with PET. A basic understanding of anatomy, wound ballistics, types of injury and potential complications is required. The initial approach should be that outlined by ATLS. Subsequently, the EP should evaluate the extremity for the presence of neurovascular or skeletal injury, obtain the appropriate consultations, and begin initial therapy. In the absence of associated injury or complicated wound, the EP should render the appropriate wound care and discharge the patient. Appropriate tetanus prophylaxis, analgesia, and follow-up care should be assured prior to discharge.
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Physician CME Questions
49. Lead missiles may lead to lead intoxication when in contact with which of the following tissue types?
A. bursa
B. muscle
C. bone
D. fascia
E. liver
50. Which of the following typically causes the most tissue destruction?
A. Yaw
B. Deformation
C. Fragmentation
51. Which of the following is a complication of a pseudoaneurysm?
A. High-output cardiac failure
B. Arterial insufficiency
C. Exsanguination
52. What is the term given to a pulsatile hematoma formed when arterial bleeding is contained by surrounding tissue?
A. True aneurysm
B. Pseudoaneurysm
C. False aneurysm
53. All of the following are hard signs of arterial injury except:
A. palpable thrill.
B. audible bruit.
C. regional ischemia.
54. Which of the following is a soft sign of arterial injury?
A. Exsanguinating hemorrhage
B. History of moderate hemorrhage
C. Paresthesia
55. A false-positive exclusion angiography exam is usually caused by:
A. arterial spasm
B. thrombus
C. aneurysm
56. Which of the following is considered a major artery within the boundaries of the lower extremity?
A. Iliac
B. Deep femoral
C. Peroneal
D. Perineal
E. Lateral tibial
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