Vascular Trauma: Extremity

Injury Characteristics

Although vascular injuries are present in a small percentage of injured patients, they are responsible for an outsized share of morbidity, mortality, and resource utilization. ^, The major vessels of the extremities account for 20% to 50% of all vascular injuries ( Table 183. 1 ). Extremity arterial injuries result from blunt and penetrating mechanisms with nearly equal frequency although blunt mechanisms are more frequently accompanied by nonvascular extremity injuries as well as concomitant non-extremity injuries. Arterial injuries occur with nearly equal frequency in the upper and lower extremities. ^{, , ,} In the upper extremity, regardless of mechanism, the most frequently injured arterial level is that of the forearm vessels. In the lower extremity, however, mechanism influences the arterial injury pattern, with the popliteal artery most frequently injured in blunt trauma and the superficial femoral artery (SFA) most frequently injured in penetrating trauma ( Fig. 183.1 ). A blunt mechanism is seen more frequently in lower extremity than in upper extremity arterial injuries, and lower extremity injuries have accordingly higher incidences of associated tissue injuries, complications, and mortality. ^,

Concomitant Extremity Injuries

In severe limb trauma, arterial injuries can coexist with fractures, peripheral nerve injuries, and significant muscle/soft tissue disruption; all of which can complicate management. ^{, ,} Fractures are seen with especially high frequency in blunt trauma, with rates as high as 80% to 100% in some series, while in penetrating mechanisms, fractures are reported in only 15% to 40% of limbs with an arterial injury. Regardless of mechanism, fractures (especially comminuted and open fractures) represent a significant risk factor for amputation when combined with extremity vascular injury. Peripheral nerve injuries are difficult to detect in the acute setting and thus they may be underreported given the generally short follow-up and lack of limb functional outcomes in the current literature. In the lower extremity, most studies report rates of around 10% with upper extremity vascular trauma associated with a rates of 40% to 50%. In general, the presence of a nerve injury does not seem to predispose to limb loss, though neurologic dysfunction may contribute to late amputation decision making if function does not improve over time. Significant soft tissue disruption often accompanies extremity vascular injuries, especially following blunt trauma. As with nerve injuries, the incidence appears to be higher in the upper extremity, reported as 40% to 70%, than in the lower extremity, for which rates are typically reported to be around 30%. The presence of a significant soft tissue deficit does appear to correlate with early amputation in lower extremity arterial trauma and can add significant complexity to initial surgical efforts.

Concomitant and Isolated Vein Injuries

The incidence of named venous injury in the setting of extremity arterial disruption ranges between 15% and 35%, though many (especially upper extremity and infrapopliteal) injuries likely go unreported. Combined major artery and vein injury implies a more severe limb injury complex but is a generally unreliable indicator of poor limb salvage prognosis, regardless of whether the vein is reconstructed or ligated. ^{, , ,} Major extremity venous injury in the absence of arterial injury is sparsely reported and is not associated with high rates of limb loss.

There is no consensus as to whether limb outcomes are improved by repair (versus ligation) of extremity venous injuries, though the redundant venous anatomy of the upper extremity distal to the axillary vein and in the calf suggests that vein ligation in these areas is safe in all but the most severely injured (i.e., mangled) extremities where all major venous outflow is disrupted. In the lower extremity, ligation carries the theoretical risk of precipitating venous hypertension potentially leading to compartment syndrome acutely and symptomatic venous insufficiency chronically. These risks remain theoretical, however, having not been consistently demonstrated. ^, Fasciotomies are performed in a high percentage of lower extremities with major venous injuries regardless of the management of the vein, and such a practice seems prudent. ^, Especially in the setting of an arterial injury, presence of a major venous injury is an argument in favor of prophylactic compartment decompression. Extremity venous injury is associated with a 30% to 50% risk of venous thromboembolism (VTE), but VTE risk does not seem to be related to whether the vein underwent repair or ligation, and recent studies have observed higher VTE rates in patients with repaired than ligated extremity venous injuries. ^, The development of limb edema is expected following ligation of a major lower extremity venous injury and is more common with ligation at the popliteal than at the femoral level, with transient swelling seen in up to 90% of ligated popliteal and 50% of ligated femoral injuries. Repair reduces the transient edema by about half, to 50% and 29%, respectively. Nearly all patients, regardless of the status of the injured vein, experience significant resolution of edema by the time of or shortly after discharge from the hospital. Significant edema is far less common after ligation of major upper extremity veins due to robust venous collaterals.

Extremity venous reconstruction following severe limb trauma can be technically demanding and should only be considered in patients who can physiologically tolerate the procedure. Reconstruction in the setting of severely compromised limb outflow resulting in early arterial reconstruction thrombosis (or early thrombosis of an arterial shunt) may help to preserve perfusion. This is most likely to be necessary in mangled extremities with venous disruption at the axillary, femoral confluence, and popliteal levels. Vein reconstructions should be preceded by distal thrombectomy performed with an Esmarch tourniquet and may consist of simple suture repair, lateral venorrhaphy, patch, or interposition graft. The short-term (days to weeks) patency of lower extremity femoral and popliteal venous reconstructions is reported to be around 70%, but large samples of longer-term follow-up of venous repairs are not available. ^{, ,} Infrapopliteal venous repairs have almost universally poor outcomes and are not recommended. In general, more complex repairs (spiral, panel, and interposition grafts) have poorer short-term patency rates than simpler repairs; the use of polytetrafluoroethylene (PTFE) grafts in larger vessels has not demonstrated inferior short-term patency compared to autologous vein. ^{, ,}

Outcomes

Extremity vascular injuries present potential threats to life, limb, and function. Severe injuries carry the acute risks of exsanguination and early limb loss, followed later in the patient’s course by the threats of late amputation or functional extremity impairment. ^{, ,} Successful management of extremity vascular trauma requires hemorrhage control to prevent mortality followed by reperfusion to avoid limb loss and, hopefully, restore limb function. When considering the outcomes of vascular limb salvage, it is important to bear in mind the short follow-up periods reported in most studies of civilian trauma patients. The majority of studies report outcomes from the period of initial hospitalization or have follow-up periods of less than one year and data on long-term graft patency and limb and patient functional outcomes are infrequent. ^{, ,}

Hemorrhagic and Ischemic Signs

Limbs with suspected arterial injury generally present in one of two ways; either with significant or ongoing bleeding or with clinical evidence of impaired distal perfusion. The clinical signs that predominate in either of these two presentations can be categorized as “hemorrhagic” or “ischemic” ( Table 183.2 ). This categorization not only helps to identify, but also characterizes the likely nature of the injury and therefore informs not only the diagnosis, but also the early management of a limb with a suspected vascular injury.

Penetrating trauma causing vascular disruption is most likely to result in a predominance of hemorrhagic signs, primarily found on initial physical exam. The presence of hemorrhagic signs indicates potentially life-threatening major arterial disruption requiring urgent measures to obtain hemostasis, especially if the patient exhibits shock. Urgent bedside hemostasis measures represent the first stage of vascular damage control (further discussed later). Temporary hemostasis should be followed by a rapid evaluation of the likely level of arterial injury and the preferred locations for inflow and outflow control. Some initial vascular damage control interventions may alter or preclude useful imaging, but if a patient with hemorrhagic signs quickly responds to initial resuscitation, a rapidly performed CTA may greatly assist operative planning. If these conditions cannot be met, urgent operative vascular control is mandatory.

Arterial occlusion resulting in ischemic signs of vascular injury is more likely to follow blunt trauma. In traumatized limbs with suspected ischemia, the distal arterial Doppler exam and measurement of the injured extremity index (ratio of the injured extremity distal systolic blood pressure to that of an uninjured extremity) if anatomically possible can provide important clinical information. Ischemic signs are frequently accompanied by concomitant fractures and other limb tissue injuries, gross identification of which may assist in general localization of the vascular injury. Though timely revascularization in the face of an ischemic limb is important, procedural planning in a limb with ischemic signs benefits from preoperative CTA imaging because reconstruction in these cases can be a complex undertaking requiring understanding of the entire limb injury picture. It is important in cases in which ischemic signs predominate to ascertain the length of time that the limb has been ischemic to best assess the need for temporary reperfusion vascular damage control strategies such as shunting and the benefit of fasciotomy.

Computed Tomographic Angiography

In recent years, CTA has emerged as the diagnostic modality of choice to identify and localize upper and lower extremity arterial injuries resulting from both blunt and penetrating trauma ( Figs. 183.2 and 183.3 ). The modality is readily and rapidly available in virtually all trauma centers and most seriously injured patients undergo contrasted CT scans as part of their evaluation within minutes of arrival. Though not universally required for identifying arterial injuries, CTA offers additional value in imaging the bone and soft tissues of the injured extremity simultaneously with arterial interrogation and can provide otherwise unavailable information regarding the status of inflow and outflow vessel candidates. ^, In addition, CTA can assist in the diagnosis of major venous injuries if a delayed phase scan is performed. Both the sensitivity and specificity of CTA in detecting even clinically occult arterial injuries approach 100%. Even difficult-to-identify below-knee and distal upper extremity arterial injuries can successfully be identified and characterized using high-resolution CT imaging. ^,

CTA has some limitations in the evaluation of limb trauma with some studies reporting inconsistent contrast opacification of the arterial system if the timing of the intravenous bolus is not optimal. In addition, imaging artifact from metal fragments can limit diagnostic utility. In patients with a large number of fragments, such as those with shotgun injuries, conventional angiography may offer better diagnostic capability than CTA, but modern artifact-reduction imaging protocols may mitigate this limitation.

Vascular Damage Control

Vascular damage control describes a complement of early temporizing maneuvers short of definitive reconstruction performed with the intent of maximizing life and limb salvage in patients with anatomically complex and physiologically significant injuries. These maneuvers present considerations unique to the treatment of patients with vascular trauma. Considerations for operative planning are presented in Table 183.3 .