Peripheral Vascular Injury

Peripheral Vascular Injury


Michael J. Sise and Steven R. Shackford


INTRODUCTION


Vascular trauma in the extremities is challenging to manage. The risk to life and limb is high and the margin for error is very thin. The presentation varies from obvious life-threatening external hemorrhage to limb ischemia in the unconscious patient with multisystem injury. An organized approach with well-planned and implemented practice guidelines converts an error-prone process into one of opportunity for effective treatment (Table 41-1). Planning and preparation are essential to the success of this approach in view of the numerous causes of delayed recognition and lack of timely treatment. The need for an organized approach is made even more compelling by the advent of trauma systems and improved prehospital care with the resulting increase in the number of patients with what were previously fatal vascular injuries arriving at trauma centers still alive, but in immediate danger of death.1,2


TABLE 41-1 Potential Errors in the Recognition, Preoperative Preparation, and Operative Management of Extremity Vascular Trauma


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This chapter reviews the pathophysiology, clinical presentation, diagnostic workup, management, and outcome of extremity vascular injuries. The educational objectives of this review include the following:


1. To identify the mechanisms of extremity vessel injury and the resulting clinical manifestations;


2. To describe an organized approach to rapidly assess injured patients for the presence of extremity vascular injuries;


3. To present management guidelines and examples of checklists to assist in the decision of which treatment options best apply and how to effectively implement them;


4. To articulate management guidelines that result in improved clinical outcomes following extremity vascular injuries; and


5. To present illustrative cases that demonstrate the principles of evaluation and management of peripheral injuries.


THE LESSONS OF WAR


The history of the surgical management of extremity vascular injury is laced with the lessons of war. In the beginning of the 20th century, the evolving science and practice of surgery included initial attempts at repairing injured blood vessels. Armed conflicts in the first two decades including the war in the Balkans and the Great War saw large numbers of limbs lost to the ligation of injured vessels with the resulting ischemic tissue loss.3,4 There were reports of successful lateral suture repair and anastomosis of injured vessels, but these techniques were not widely adopted.3 During World War II ligation continued to predominate the management of injured vessels.4,5 It was not until the Korean War that vessel repair by combat surgeons was employed on a widespread basis.6 The timing of arrival of casualties to combat hospital was, in part, a determinant of this successful change in management. Korea was the first conflict in which aeromedical evacuation was widely used. Casualty arrival times decreased significantly and injuries that were previously fatal were managed successfully by surgeons in mobile hospital units.6 In the Vietnam War, the practice of vascular repair coupled with an even more efficient evacuation system led to the development of many of the current techniques and management guidelines in the care of extremity vascular injuries. The Vietnam Vascular Registry maintained by Rich et al. proved a valuable clinical research tool in this process.7


The civilian experience in the subsequent three decades following the Vietnam War further improved the care of extremity vascular injury. The epidemic of urban violence in the 1990s provided urban trauma centers with extensive experience in the management of these injuries.8 The management guidelines and recommendations that resulted steadily advanced the practice of trauma vascular surgery. Surgeons trained in civilian trauma centers went to war in Operations Enduring Freedom and Iraqi Freedom prepared to manage extremity vascular injuries. These combat surgeons took the clinical management one step further with the widespread use of vascular damage control techniques including intraluminal shunt placement and delayed primary repair.9 The experience gained was brought home to civilian centers with valuable applications in the management of patients with extremity vascular injuries. The lessons of war coupled with the organized approach to trauma management in civilian trauma centers resulted in the guidelines and recommendations included in this chapter.


EPIDEMIOLOGY


Vascular injuries of the extremities are infrequent but not uncommon in both civilian and military trauma patients.1,9 They are predominantly a problem in young men in their third and fourth decades.1,2 Whether blunt or penetrating mechanisms, they occur in association with high-risk behavior.1,10 Substance abuse, violence, and late night hours are commonly associated factors in civilian extremity vascular injuries. The trauma center’s rates of blunt versus penetrating injury will largely determine the most common local causes of these injuries. Civilian centers have a distinctly different pattern of extremity vascular injuries compared with combat medical facilities. Blunt trauma with extremity fractures, small-caliber handguns, and knives cause the vast majority of civilian extremity vascular injuries. In military series, high-caliber rounds and explosive ordinance with shrapnel are the predominant wounding agents. The force, trajectory, and tissue damage associated with military injuries are much more devastating than those seen in civilian series.1,7,9


Survivable vascular injuries are most common in the extremities because of the lethality of torso vascular wounds. Both combat wounds and interpersonal civilian violence yield a significant rate of extremity vascular injuries. Vascular trauma occurs in less than 2% of combatants in military series and in less than 4% of patients in civilian series.1,8,10,11 Overall, vascular injuries occur most commonly in the extremities. This is due partly to selection bias because great vessel injuries of the torso, head, and neck are highly lethal and the patients succumb before arrival at the trauma center.


The great majority of vascular injuries are due to penetrating trauma. In the recent military experience in the Middle East, 89% of vascular injuries were due to a penetrating mechanism, either fragment wounds from explosive devices (64%) or gunshot wounds (25%).8 Penetrating trauma also predominates in the civilian setting, particularly in some urban environments where the incidence can be as high as 90%, most of which are due to gunshot wounds.1 Rural settings have a higher proportion of blunt injuries, but they still make up less than 45% of the total.10 Vascular injuries do not occur in isolation. Because the vascular structures often lie in close proximity to nerves and bones, associated skeletal and nerve injury occurs in approximately 25% of patients.1,6,7,9


Mattox et al. documented a 400% increase in civilian cardiovascular injuries in Houston between 1958 and 1988, with 50% of all vascular injuries over this 30-year period occurring in the last 10 years of this study.1 The recent decline observed in urban violence has mitigated this trend somewhat, but random shootings with multiple casualties still occur.


Iatrogenic arterial injuries continue to increase. This increase parallels the rapid rise in endoluminal procedures, which increased 40% between 1996 and 2003.12 The postprocedure iatrogenic arterial injury rate is now 0.6% and appears to be specialty related.13 Cardiologists have a significantly higher rate (1.3%) than either the interventional radiologists (0.9%) or the vascular surgeons (0.5%).13


PATHOPHYSIOLOGY


Arteries and veins are composed of three tissue layers including the outer adventitia of connective tissue, the central media of smooth muscle and elastic fibers, and the inner intima or endothelial cell layer. Trauma to a blood vessel (artery or vein) can produce hemorrhage, thrombosis, or spasm, either alone or in combination, depending on the magnitude of the force applied to the vessel. Hemorrhage occurs when there is a transmural defect—all of the layers (intima, media, and adventitia) are disrupted or lacerated. If the bleeding is controlled by the surrounding tissue (i.e., muscle or fascia), a hematoma is produced, which may or may not be pulsatile. If bleeding is not controlled or tamponaded, exsanguination can occur. Thrombus or thrombosis is produced if there is damage to the intima and the subendothelial tissues are exposed to the bloodstream. Local thrombus may embolize or propagate and eventually occlude the lumen. The injured intima may form a flap that can prolapse into the lumen (as a result of blood flow dissecting under it) producing partial or complete obstruction. Trauma to surrounding bony structures may cause external compression of the vessel, interrupting flow and producing thrombosis. Spasm or segmental narrowing is the result of mechanical trauma, such as occurs if the vessel is stretched or contused (Fig. 41-1). Severe spasm can also be produced by bleeding adjacent to a vessel due to the vasoconstrictive effects of hemoglobin. Spasm, by reducing the cross-sectional area of the vessel, reduces flow.


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FIGURE 41-1 Severe spasm of tibial vessels following blunt force tibia and fibula fracture and internal fixation. After catheter-based nitroglycerin drip for 24 hours, normal ankle pulses and normal CT angiogram with normal caliber and no occlusion of all three calf vessels. Patient made a full recovery.


Penetrating injury has a much different pathophysiology than blunt injury. These injuries tend to be more discrete or focal, while blunt injury is more diffuse with injury not only to the vascular structures but also to the adjacent bone, muscle, and nerves. The diffuse nature of the blunt injury not only affects the major arteries and veins but also disrupts smaller vessels that would normally provide collateral flow around an occluded or narrowed vessel. As a result, ischemia is worsened or exaggerated. Penetrating injury is generally classified as low velocity (<2,500 ft/s). This includes stab wounds, fragment injuries, and low-velocity gunshot wounds. High-velocity (>2,500 ft/s) wounds, such as those caused by a military assault rifle wound, produce significantly more tissue damage than low-velocity weapons due to the energy imparted. The kinetic energy of a wounding missile equals the mass of the projectile multiplied by the velocity squared. The missile creates a rapidly expanding and rapidly contracting cavity that can reach a size equal to 30 times the diameter of the projectile. This occurs at right angles to the missile tract and stretches and tears the adjacent tissue. Fragments of the deteriorating projectile become missiles themselves and cause additional injuries.14


In addition to the acute pathophysiology produced by hemorrhage and thrombosis, trauma can produce subacute or chronic injuries, which may not become apparent for years. The most common of these chronic injuries are arteriovenous fistula and pseudoaneurysm. An arteriovenous fistula typically occurs after penetrating trauma that causes injury to both an artery and a vein in close proximity. The high-pressure flow from the artery will follow the path of least vascular resistance into the vein producing local, regional, and systemic signs and symptoms (Fig. 41-2). These include local tenderness and edema, regional ischemia from “steal,” and congestive heart failure if the fistula enlarges.15 A pseudoaneurysm is a result of a puncture or laceration of an artery that bleeds into and is controlled by the surrounding tissue (see Section “Case 6,” Fig. 41-21). The artery remains patent; blood flows into and out of the pseudoaneurysm—much like the ebb and flow of ocean water into and out of a tide pool. They can enlarge and produce local compressive symptoms, erode adjacent structures, or, rarely, be a source of distal emboli.15 Initially, they can be clinically occult, but with time become symptomatic.


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FIGURE 41-2 Acute axillary artery pseuodoaneurysm and arteriovenous fistula following stab wound in right axilla. Vessels repaired by simple closure.


Not all arterial injuries require an intervention. During the past two decades, it has been convincingly demonstrated that many asymptomatic traumatic vascular injuries have a benign natural history and either completely resolve or remain stable.8,16 At the present time it is impossible to predict which lesions will heal, which will progress and remain asymptomatic, and which will eventually develop either acute or chronic symptoms.


Acute interruption of blood flow to an extremity results in a number of systemic pathophysiologic disturbances that may threaten life as well as the affected limb. Ischemia results from a failure of oxygen delivery to meet tissue metabolic needs. The vulnerability of a tissue to ischemia depends on its basal energy requirement, substrate stores, and duration and severity of the ischemic insult. Peripheral nerves are most vulnerable to ischemia because they have a high basal energy requirement and virtually no glycogen stores. Therefore, motor and sensory deficits are often the first manifestations of arterial occlusion. Skeletal muscle is more tolerant of decreased blood flow; histologic changes are not evident unless ischemia has been present for ≥4 hours. Reversible changes occur in 4–6 hours following onset of ischemia if reperfusion is established by the end of that interval. The more complete the interruption of arterial inflow, such as occurs with occlusion of a major arterial conduit and disruption of collateral vessels, and the longer the duration of interrupted flow, the greater the potential for irreversible ischemic damage. After prolonged complete ischemia, damage may be extended rather than reversed by reperfusion.


Reperfusion injury is initiated with the reintroduction of oxygen and the conversion of hypoxanthine, a metabolite of ATP in ischemic tissue, to xanthine with the generation of the highly reactive superoxide and hydroxyl radicals. Leukocytes are thought to be the major source of free radicals in reperfused muscle. Such radicals and reactive oxygen species attack cell membrane lipids, proteins, and glycosaminoglycans, disrupting the integrity of the capillary, resulting in microvascular occlusion and elevated interstitial fluid pressure. This leads to a “no-reflow” phenomenon, and, ultimately, to irreversible ischemia and necrosis of both nerve and muscle.17 With muscle necrosis or rhabdomyolysis, myoglobin and potassium are released into the circulation, which may lead to fatal arrhythmias and renal failure. Thus, in addition to potential local and regional effects on limb dysfunction and limb loss, acute interruption of extremity blood flow can have systemic consequences of organ failure and death if not recognized promptly and treated aggressively.18,19


Image Compartment Syndrome

One of the most devastating early complications of extremity vascular injury is compartment syndrome. All muscle compartments in the extremities are vulnerable to intracompartmental hypertension that can lead to muscle necrosis. This may occur primarily from decreased perfusion and ischemia, secondary to intracompartmental hemorrhage from direct trauma, or after successful revascularization with reperfusion edema. Compartment syndrome results from swelling of muscle in a confined space (i.e., bound by inflexible structures such as fascia and bone) due to either reperfusion or crush injury. This swelling increases the tissue pressure within the confined space or “compartment” compressing both venous and lymphatic outflow as well as arteriolar inflow, further increasing tissue pressure and reducing perfusion, ultimately resulting in ischemic neurolysis and myonecrosis if unrecognized and not treated promptly. Compartment syndrome occurs most commonly in the muscle compartments of the lower leg. It may be life threatening because of the systemic effect of rhabdomyolysis, myoglobin-induced renal failure, and hyperkalemia.8,19


Proximal extremity venous obstruction accentuates the rise in compartmental pressure and is often a major contributing factor to compartment syndrome The anterior compartment of the calf is the least compliant area of muscle surrounded by fascia in the extremities and is the most vulnerable to compartment syndrome. Acute complete traumatic occlusion or ligation of the popliteal vein may cause enough increase in compartment pressure to cause compartment syndrome, particularly in the anterior compartment. The upper extremity has more extensive venous drainage and is less prone to develop compartment syndrome than the lower extremity following venous occlusion or ligation. Compartment syndrome follows less than 10% of brachial artery injuries and is not a complication of upper extremity venous ligation unless there is extensive soft tissue injury.20,21 Although the anterior compartment and forearm are the most susceptible areas, compartment syndrome may occur in any area of extremity muscle including the foot, hand, thigh, upper arm, and buttocks.


Image Missile Emboli

Intravascular migration of bullets, shotgun pellets, and other foreign bodies is uncommon and occurs in less than 1% of extremity vascular injuries.22,23 The most common occurrence is the migration of small-caliber shotgun pellets from the proximal extremity veins through the right side of the heart and into the pulmonary circulation. Larger bullets may enter arteries and embolize to distal vessels causing ischemia. Bullets that enter the great veins may embolize proximally to the heart or, by the force of gravity, travel in a retrograde fashion into the lower extremity veins.


Diagnosis requires a high index of suspicion and a thorough peripheral vascular examination. Entrance wounds without associated bullets on radiographs should raise the alert that bullet embolism may have occurred. Extremity radiographs or fluoroscopy should be performed to rule out bullet embolism when they are unaccounted for in proximity to entrance wounds or along suspected trajectories within the patient.


Acute limb ischemia requires prompt operation for bullet retrieval. In the absence of limb threat, angiography and snare deployment under fluoroscopy can be successful in bullet retrieval. A cutdown under local anesthesia at the snare introduction site is usually required to remove the retrieved bullet. Asymptomatic small-caliber shotgun pellets in the extremities are best left alone.


PROGNOSTIC FACTORS


There are a number of factors that are significant in determining the outcome of extremity vascular injury. These include the location of the injury and mechanism, amount of hemorrhage, severity of associated musculoskeletal injury, time interval between injury and control of hemorrhage and restoration of flow, and the preexisting health status of the patient. All of these factors influence outcome and need to be considered in the management of extremity vascular injury. However, the most critical factor remains the time between injury and control of hemorrhage and restoration of flow. This generates a time urgency in the diagnostic workup and treatment of these injuries that must always be part of the management strategy.


Both recent military and civilian series demonstrate the importance of timely treatment in successful limb salvage following vascular injury in the extremities.1,7,9,24 Delays beyond 6–12 hours were associated with a rise in limb loss from 22% to 93% in a recent combat series. The association with musculoskeletal and soft tissue trauma also impacts this salvage rate because of the loss of collateral circulation. These recent reports reaffirm the tradition concept of a “golden period” of 6–8 hours following extremity vascular injury in which adequate flow must be established to avoid limb loss.


Not only do blunt mechanisms of injury cause greater damage to extremity vessels and surrounding structures than penetrating trauma, but their effects are also more widely distributed up along the course of the extremity and often involve associated significant torso injuries. These injuries are more likely to be difficult to diagnose than more clinically obvious and often localized penetrating injuries. Major torso injuries divert attention away from the extremities and the overall trend is for a delay in the recognition of blunt vascular injuries. This delay compounds the already worsened outcome because of the commonly associated soft tissue and musculoskeletal blunt force injuries.


In penetrating injuries, the wound force of gunshot wounds varies according to the type of projectile and, more importantly, its velocity. High-velocity, assault weapon–style injuries are extremely destructive in the extremities and have a high associated limb loss rate. Civilian handgun wounds with their low velocity have a much better prognosis. Knife wounds remain the least destructive mechanism of vascular injury and are often the easiest to manage. However, in the upper extremity, the association of median nerve injury with brachial artery lacerations negatively impacts overall functional outcome.


The muscle mass and collateral flow is significantly different in the upper versus lower extremities. The arm tolerates arterial occlusion much better than the lower extremity with its large muscle groups, greater length, and relatively poor collateral flow. Amputation rates in the lower extremity are approximately double those in the lower extremity following traumatic arterial occlusion in both military and civilian series.1,7,9 Both brachial artery and popliteal artery occlusions, however, have a very high risk of eventual limb loss and require the same expeditious workup and treatment. The disparity in size and collateral blood flow between the extremities also makes complications including compartment syndrome and the venous insufficiency more likely and more morbid in the lower extremity. However, because of the importance of hand function, the long-term effects of nerve damage are much more consequential in the upper extremity.


CLINICAL PRESENTATION


The presentation of extremity vascular injury varies from obvious life-threatening external hemorrhage from penetrating injury to occult extremity ischemia from blunt force arterial disruption and occlusion. A history of active bleeding, hematoma, or the findings of arterial occlusion and ischemia are present in most extremity vascular injuries.1,7,9,2527 Less commonly, extremity vascular occlusion is masked by the presence of multisystem torso and extremity injuries. Failure to systematically evaluate the extremities with a clinical vascular exam augmented by Doppler studies is one of the most common causes of preventable limb loss. Blunt force injury resulting in extremity fracture must always be assumed to place the regional vascular structures at risk for injury. Fracture and dislocation patterns are also key indicators of the risk of extremity vascular injury. In the upper extremity, supracondylar humerus fracture is associated with a risk of brachial artery laceration. In the lower extremity, posterior knee dislocation carries a high risk of popliteal artery injury.


The presence of unexplained hemorrhagic shock in patients without evidence of head, neck, or torso injury should redirect attention to apparently trivial extremity lacerations. This is particularly important in wounds in the antecubital fossa, groin, and popliteal fossa. Initial external hemorrhage from laceration of the regional vessels may have led to hypotension with subsequent thrombosis and cessation of bleeding. There is the potential for large extremity dressings to mask recurrent hemorrhage after restoration of circulating blood volume and these should be promptly removed to assess the underlying wounds.


Delayed presentation of major complications of extremity vascular injury, although uncommon, should be considered in all blunt and penetrating extremity wounds. The tertiary survey later on the day of admission or the next morning should include a reassessment of extremity blood flow. This includes palpation of the distal pulses, assessment of the extremity for hematoma or muscle tenderness, and, if appropriate, Doppler interrogation of flow. No cast or dressing placed by an orthopedic surgery colleague should be left in place if there is any question about the adequacy of blood flow or the possibility of a missed vascular injury.


Compartment syndrome may develop insidiously. Irreversible tissue damage can occur in the absence of clinical signs and symptoms. When present, pain on passive stretch or pain out of proportion to findings should alert the examining physician to the possibility of compartment syndrome. Palpable distal pulses remain intact long after muscle blood flow has ceased in the compartment with tissue pressures above 25 mm Hg. Muscle and nerve necrosis can occur well before major arterial inflow is occluded. Therefore, the pulse examination is not sufficient to detect the development of a compartment syndrome. Measurement of compartment pressure is the only reliable means of detecting the presence of compartment syndrome.


DIAGNOSTIC EVALUATION


Image Physical Examination

A thorough physical examination with careful palpation of extremity pulses remains the basis for accurate and timely diagnosis of extremity vascular injury. This includes a vascular and neurologic examination of each extremity with careful palpation of peripheral pulses, assessment of color, warmth, and capillary refill. There is an unfortunate tendency to “overcall” the presence of pedal pulses. Once any examiner calls a pulse present when it is, in fact, absent, a cascade of errors may be initiated that result in limb-threatening ischemia. When in doubt, declare the pulse absent and add adjunctive assessment measures to make certain adequate perfusion is present.


There are very distinct physical findings that clearly indicate the presence of extremity vascular injury. In addition to these “hard signs,” there are less obvious but equally important “soft signs” that should bring attention to the possibility of extremity vascular injury (Table 41-2). The hard signs indicate a high probability of major vascular injury requiring immediate surgical repair.2527 Lack of recognition of these hard signs of vascular trauma on the initial evaluation of injured extremities is the most common reason for the development of limb-threatening complications.1,19,24 The presence of soft signs of vascular injury mandates further workup with vascular imaging techniques and, less frequently, surgical exploration.25,26


TABLE 41-2 “Hard” and “Soft” Signs of Vascular Injury


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Doppler assessment of pulsatile flow in the extremity is the primary adjunctive measure to physical examination. The experienced examiner can assess flow based on the character of the audible Doppler signals. However, the best way to use the Doppler device is in conjunction with a systolic blood pressure determination. The manual blood pressure cuff is placed at the wrist or ankle in the injured extremity and the probe placed over the distal vessel. The cuff is slowly inflated and the cessation of signal indicates the systolic blood pressure at the level of the cuff. The uninjured contralateral extremity and an uninjured arm pressure are determined. The normal ankle–brachial index is 1.1. Unless the patient has preexisting peripheral vascular occlusive disease, the ankle–brachial index should be at least 0.9 and there should be less than a 20 mm Hg difference between extremities.28 An absolute pressure below 50–60 mm Hg at the wrist or ankle indicates immediate limb-threatening ischemia in the patient with a normal systemic blood pressure.


Beware the patient with advanced peripheral vascular disease, particularly if it is related to diabetes. Calcified extremity vessels are noncompressible and cannot be occluded by inflation of the blood pressure cuff (even with inflation pressures of 200–300 mm Hg), resulting in a falsely elevated systolic pressure. Physical examination may be unreliable in the detection of compartment syndrome. This is particularly true in patients with altered mental status from injury, intoxication, or medication and who have a lower extremity neurologic deficit. When present, pain on passive stretch or pain out of proportion to findings should alert the clinician to the possibility of compartment syndrome. In such cases it is best to directly measure the compartment pressures.


Image Arteriography

The traditional debate over the role of preoperative arteriography for patients with extremity vascular injury was based on two key facts. First, there are many injuries easily and accurately diagnosed by physical examination and, second, time can be lost in obtaining formal catheter angiography leading to prolonged ischemia and poor outcome. There remain a significant number of extremity vascular injuries that are best managed by immediate operation and in which arteriography may be a needless waste of time and resources. There is an arteriogram time equation that should be considered in the workup of these injuries. Is the information obtained worth the time delay in restoring flow in the ischemic limb? Even if there is an angiogram suite on standby, ready to go, it requires a minimum of 90 minutes to obtain formal arteriography. The second part of this calculation answers the question: will the arteriogram direct the choice of operative versus nonoperative therapy or focus the operative approach to improve outcome? Multilevel blunt extremity injuries associated with ischemia and multiple penetrating injuries to an extremity (such as occurs with wide pattern shotgun blast injury) fall into this category and, thus, necessitate contrast imaging.


The advent of widely available high-resolution multidetector CT angiography has radically changed the approach to contrast imaging for extremity vascular trauma and made the old debate largely irrelevant. Catheter arteriography for the evaluation of injured extremities has become relatively uncommon at most trauma centers. High-resolution CT scanning with the appropriate imaging protocols produces rapidly available visualization of extremity vessels that rivals that of catheter arteriography (see Section “Case 6”). This results in images available in minutes rather than hours. The reluctance to perform catheter angiography in the past because of this delay has been replaced with a liberal use of CT angiography. The indications remain the same for both methods of vascular imaging (Table 41-3). However, in diffuse extremity injury from shotgun wounds, catheter-based angiogram may be more accurate than CT angiography because of the scatter effect of the numerous metal projectiles that obscure the arterial lumen. Also, catheter angiography remains essential in those patients who may require an endoluminal therapy, such as infusion of a vasodilator or placement of a covered stent, at the time of the diagnostic angiogram. Patients with spasm without significant arterial wall injury may benefit from this added capability.


TABLE 41-3 Indications for Arteriography in Patients with Extremity Injuries


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Single-injection arteriogram in the trauma room or operating room is a quick and accurate method of definitive imaging in unstable patients with associated torso injuries or multilevel extremity injuries who require immediate operation. This simple and direct technique is quickly performed and effective in the unstable patient with multiple injuries who needs prioritization of management by evaluating extremity blood flow (see Section “Case 7,” Figure 41-27). The technique of trauma resuscitation room arteriogram is described in Table 41-4.


TABLE 41-4 Technique for “Single-Shot” Extremity Arteriography


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Image Noninvasive Evaluation

The widespread availability of duplex scanning led to its application in the workup of vascular imaging.28 However, it has not proven useful in the diagnosis of acute arterial injury because it requires the presence of a skilled vascular technologist to perform the test and an experienced provider to interpret the study—neither of which is usually available on an expedient basis. Duplex color flow imaging has great usefulness in the diagnosis of chronic injuries, such as pseudoaneurysms and arteriovenous fistulae, and in the postoperative follow-up of vascular repairs.


Image Practice Recommendation for Extremity Vascular Diagnostic Evaluation

An outline of the recommended approach to the prompt diagnosis of extremity vascular injury is detailed in Fig. 41-3. Physical examination remains the most important element of this process. Common sense dictates that those with obvious injury go directly to the operating room to delineate and repair the injury. Imaging with either high-resolution CT angiogram or catheter arteriography must make sense in terms of the expense of time and the value of the results in deciding and directing the operative approach.


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FIGURE 41-3 Diagnostic evaluation of extremity vascular injury.


MANAGEMENT


Image Minimal Vascular Injury and Nonoperative Management

The widespread application of arteriography in the evaluation of injured extremities results in the detection of clinically insignificant lesions. There is now an extensive body of experience with lesions that are not clinically significant. These minimal vascular injuries include intimal irregularity, focal spasm with minimal narrowing, and small pseudoaneurysms. They are often asymptomatic and usually do not progress.


A small, nonocclusive intimal flap is the most common clinically insignificant minimal vascular injury. The likelihood that it will progress to cause either occlusion or distal embolization is approximately 10–15%.16,29 This progression, if it occurs, will be early in the postinjury course. Spasm is another common minimal vascular injury. This finding should resolve promptly after initial discovery. Failure of the return of normal extremity perfusion pressure indicates that a more serious vascular injury is present and intervention is needed. Small pseudoaneurysms are more likely to progress to the point of needing repair and must be actively followed with duplex color flow imaging. Arteriovenous fistulae always enlarge over time and should be promptly repaired. Considerable evidence suggests that nonoperative therapy of many asymptomatic lesions is safe and effective. However, successful nonoperative therapy requires continuous surveillance for subsequent progression, occlusion, or hemorrhage. Operative therapy is required for thrombosis, symptoms of chronic ischemia, and failure of small pseudoaneurysms to resolve.


Image Endovascular Management

The use of endovascular therapy for the treatment of atherosclerotic arterial disease has become widespread. What began as a simple balloon dilation in the common iliac arteries over 30 years ago has grown to include a wide variety of techniques. Whether it is endoluminal stent deployment for occlusive lesions or aortic aneurysms, there is a strong tendency to generalize from the elective use in nontrauma patients to the treatment of acute vascular injuries. Almost every major trauma center has its share of cases successfully treated with the use of elective techniques for acute vascular lesions. However, the evidence to support these approaches is not well developed and there have been problems. A review of available evidence combined with common sense should help define the current role of endovascular management of traumatic injuries.8,30,31


Extremity vascular injury resulting in hemorrhage is best treated by promptly performed open surgical techniques. The use of stent grafts in the extremity vascular injuries is becoming more common.30,31 However, the results are not yet well documented. Caution may well be the best approach. Covered stents are easily placed in partially occluded vessels and although they have initially favorable early patency rates, they are prone to occlusion. In comparison, autologous vein interposition grafts have excellent long-term patency rates and remain the gold standard for vascular repairs in the extremities.


Catheter-directed therapies for hemorrhage from branch vessels in the extremities can be effective in successfully managing these injuries. These measures, in addition to ultrasound-guided thrombin injection, are effective in iatrogenic acute pseudoaneurysms following invasive procedures; this approach is not effective in most extremity vascular injuries. The small hole in the artery following removal of an arterial sheath is very different than the larger defects seen with vascular trauma. The risk of complete arterial thrombosis or distal emboli is high with this approach.8,19


Who Should Perform Endovascular Repairs

Have the right person do the right thing in the right place at the right time. This simple rule needs to apply at all times. Endovascular surgery, like all operations, should be performed by readily available trained clinicians. In most centers this includes the interventional radiologist. Other centers have catheter-trained vascular surgeons and a few others have trauma surgeons who are capable of performing catheter-based vascular interventions.


It does not require a fully capable endovascular operating room suite to perform endovascular techniques. A modern digital C-arm with digital subtraction angiography capability for fluoroscopy, lead aprons for the OR team, and the appropriate guidewires and catheters turns any OR into an endovascular capable room. However, this cannot be improvised the first time it is needed. Planning and preparation are essential for success. A team approach is essential to be ready for the opportunity to perform endovascular techniques when indicated. This approach is most successful in centers with an active elective endovascular program.


Operative Management

The successful operative management of extremity vascular injuries requires both prompt control of hemorrhage and timely restoration of adequate perfusion. These priorities must be orchestrated with the overall care of the patient. Both adequate resuscitation and the role of damage control are important factors in the management of extremity vascular injuries. Secondary considerations include adequate tissue coverage of repair sites, orthopedic surgical procedures, the prevention of compartment syndrome, early recognition of thrombosis of repaired vessels, and wound management. Minimal vascular injuries may be successfully managed nonoperatively with careful observation. There is also a limited, but emerging, role for endovascular therapy.


Who Should Perform Vascular Trauma Surgery

In an era of fewer open vascular procedures and falling numbers of major vascular cases performed during surgical training, the repair of extremity vascular injury may not be within the reasonable practice capabilities of many trauma surgeons. Operative procedures to manage vascular injuries should be limited to those surgeons who are capable, experienced, and qualified. This is not a trivial matter. Board certification in vascular surgery is not enough to qualify a surgeon as capable to handle these injuries just as the lack of certification does not necessarily disqualify a surgeon. Many surgeons who perform elective vascular surgery are not sufficiently experienced in the management of vascular trauma. Conversely, there are many trauma surgeons who are very skilled in vascular technique by virtue of their interest and experience. Surgeons with experience in vascular techniques and management of vascular injuries need to be available at all trauma centers to deal with these challenging injuries. This may be provided by members of the primary trauma on-call panel or vascular surgery specialists available on a backup call panel.


Image Preoperative Preparation

Successful operative management of extremity vascular injuries requires a systematic approach with careful preparation. This process is very amenable to a checklist to assure thorough preparation and to avoid errors (Fig. 41-4). There is considerable risk involved if the care of the extremity vascular injury is not properly orchestrated with the overall care of the patient. This begins with airway control, adequate intravenous access, and availability of blood products. The administration of these blood products, however, should not begin before obtaining control of hemorrhage unless the patient is profoundly hypotensive.3234


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FIGURE 41-4 Preparation checklist for extremity vascular repair.


Damage control resuscitation with permissive hypotension, avoiding unnecessary fluid infusion, prompt hemorrhage control, and restoration of blood volume with blood products is the best approach in patients with hemorrhagic shock. If the blood pressure remains below 80–90 mm Hg, the goal should be to provide adequate volume restoration with type O-negative packed cells and type AB fresh frozen plasma infusion to support prompt transport to the operating room for definitive hemorrhage control. Volume infusion that raises the blood pressure above a systolic of 90–100 mm Hg may increase bleeding and negatively impact outcome particularly if the infusion delays transport to the operating room.33,34 Crystalloid infusion risks causing both recurrent hemorrhage and dilutional coagulopathy and should be avoided. There is evidence that, once hemorrhage is controlled, restoring blood volume by transfusion with equal ratios of units of packed cell, fresh frozen plasma, and platelets improves outcomes.35


Extremity hemorrhage from vascular injuries requires prompt control. There are a variety of commercially available disposable tourniquets that are very effective in providing temporary control. The favorable results from the widespread use of tourniquets in Operations Enduring Freedom and Iraqi Freedom are compelling.9 There should be no hesitation to use them when indicated in the care of civilian injuries. However, proper use requires appropriate placement on the extremity proximal to the area of injury with sufficient pressure to occlude flow without crushing tissue. The time of placement should also be carefully recorded to keep track of occlusion time and avoid permanent damage from ischemia and delayed restoration of adequate flow. There is no role and no need for blind clamp placement in the injured extremity with active hemorrhage. Properly placed tourniquets or a gloved hand compressing the bleeding site during transfer to the operating room is the only appropriate measure. There is also no role and clear danger involved in local wound exploration in the trauma resuscitation bay for vascular control. The operating room with all its capabilities is the proper place for exposure and control.


Preoperative preparation should include the administration of broad-spectrum preoperative antibiotics and, if there is a penetrating wound or open fracture, tetanus toxoid. If there is an isolated extremity injury without significant hemorrhage, a bolus of 5,000 U of heparin should also be given intravenously. However, avoid systemic heparinization in patients with head, torso, or multiple extremity injuries. The most commonly omitted step in preparation to repair extremity vascular injury is a failure to document preoperative extremity neurologic examination findings. The presence of a neurologic deficit after operative vascular repair without knowing the preoperative status presents a very difficult management challenge. This may prompt unnecessary reexploration. A new neurologic deficit after vascular repair merits investigation and, possibly, reoperation. Therefore, a thorough preoperative neurologic examination and careful documentation are needed to compare with postoperative status and effectively manage potential complications.


Early involvement of orthopedic surgery and plastic and reconstructive surgery colleagues is essential in the presence of fractures or extensive soft tissue injuries associated with extremity vascular injuries. Consultation should be undertaken immediately on recognition of these injuries to involve these specialists in preoperative planning and intraoperative decision making. The sequencing and conduct of the operation should also be discussed with these colleagues.36 For example, the initial use of temporary vascular shunts to reperfuse an injured extremity followed by orthopedic stabilization can remove the sense of urgency to definitively restore blood flow. Extensive soft tissue injuries may compromise the proper coverage of vascular repairs and fracture fixation. The choice of definitive internal fixation versus external fixation of fractures requires consideration of both the vascular repair and the extent of soft tissue injury and plans for coverage and reconstruction. The discussion and subsequent decision making is a preoperative step that cannot be deferred without risking the ultimate successful outcome.


Once operative priorities have been established in patients with extremity vascular injuries, it is important to communicate with the operating room. Proper preparation includes the availability of the appropriate instrument sets, appropriate positioning of the patient, availability of sutures and graft material, and other ancillary equipment, such as loupe magnification and coaxial lighting. Communication with the anesthesiologist involved in the planned operation should also occur and include an assessment of the patient’s resuscitation needs, estimated duration of operative intervention, plans for multispecialty approach, need for blood products and a cell saver device, and estimated duration of operation. Vascular repairs in the extremities require general anesthesia, an arterial line for blood pressure monitoring, and adequate venous access. Warming devices are also essential to prevent hypothermia. Even the most experienced vascular surgeon plans on a considerably long operative time to complete these repairs.


Specific equipment, suture, and graft material requests should be communicated as soon as possible to the operating room team. Most operating rooms have major vascular instrument sets for the extremities. Ask to have them opened and ready. Prepare heparinized saline (5,000 U of heparin per 500 mL of saline for injection for a 10 U/mL solution) for locally flushing vessels. Low-molecular-weight Dextran (40,000) and papaverine hydrochloride (30 mg/mL) for treatment of vascular spasm should also be available in the operating room. Also request the appropriate vascular sutures. For suture repair, 5-0 Prolene on a C-1 needle is very useful. A variety of sutures should be available for vascular anastomosis. Request 5-0 Prolene on a BV-1 and C-1 needle or 6-0 Prolene on a BV-1 needle. For tibial and forearm vessels, either a 6-0 Prolene on a BV-1 needle or a 7-0 Prolene on a BV-175 needle should be available. All sutures should be of appropriate length and be on double-armed needles. PTFE graft material of various sizes (6 and 8 mm diameter) with external rings should also be readily available if saphenous vein is not of sufficient size or an extra-anatomic bypass is needed in injuries associated with extensive soft tissue loss.

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Oct 26, 2017 | Posted by in CARDIOLOGY | Comments Off on Peripheral Vascular Injury
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