Diagnosis

Regardless of the mechanism of injury, the affected extremity should be examined for active hemorrhage, hematoma, or a palpable thrill. Perfusion is evaluated by inspection of skin color, palpation of distal pulses, assessment of venous refilling and capillary refill, and determination of neurologic function. Areas of paresthesia, hypesthesia, or paralysis usually correlate with arterial injuries. Table 98.1 lists “hard” (more definitive) and “soft” (more equivocal) signs of vascular injury.

The ankle-brachial index (ABI) is calculated by dividing the systolic pressure in the traumatized extremity by the systolic pressure at the brachial artery. An ABI of less than 0.9 indicates major vascular injury but should be considered a “soft” sign because it does not mandate surgical exploration by itself.

Patients who present with “hard” signs require no additional diagnostic testing prior to intervention. In patients with “soft” signs, particularly in those with an ABI of less than 0.9, the next diagnostic modality of choice is arteriography. With the exception of knee dislocation, in the absence of “hard” findings, proximity of the injury to a major vessel is not an absolute indication for arteriography. Arteriography is always recommended after knee dislocation to rule out blunt injury to the popliteal artery, as well as after shotgun wounds because of the multiple small projectiles. The use of computed tomography angiography (CTA) is becoming more frequent and is considered an excellent diagnostic tool for the assessment of vascular injury in an otherwise stable patient. The availability of CTA allows for rapid diagnosis and, if vascular injury is seen, can prompt either endovascular or surgical intervention. Although many non-invasive diagnostic modalities are not widely available and can be difficult to perform or interpret, the use of duplex ultrasonography is appropriate in patients with “soft” signs and an ABI greater than 0.9.

Operative Interventions

Patients with “hard” signs should be immediately transported to the operating room (OR) or interventional radiology (IR) suite for surgical exploration or repair. An intraoperative arteriogram may be performed if ongoing diagnostic information is necessary. Major arterial injuries are initially controlled with vascular clamps, resection of the injured segment of artery, and placement of an interposition graft to restore flow. Restoration of flow with smaller arterial injuries can sometimes be achieved with a primary anastomosis or use of a vein patch. An intraluminal shunt may be used to perfuse the extremity temporarily while other injuries are addressed (e.g., unstable fracture). Arterial reconstructions should always be evaluated at the end of the operation with an intraoperative arteriogram.

Large venous injuries are usually repairable; however, with the exception of the popliteal vein, they can usually be ligated if necessary. The decision to ligate is based on the hemodynamic stability of the patient and the complexity of the injury.

The surrounding fascia should be opened to release surrounding pressure on the vasculature (i.e., fasciotomy) when there has been a significant delay in restoration of perfusion, preoperative hypotension, significant swelling or crush injury to the extremity, combined arterial and venous repairs, or ligation of a major vein.

Postoperative Care

The goals of postoperative care are resuscitation of intravascular volume, rewarming, and correction of acidosis. Acidosis, hyperkalemia, and edema often result from reperfusion of the ischemic extremity. The degree in which they occur is directly proportional to the time and total area of tissue that sustained malperfusion. Frequent assessment of the integrity of the affected vascular bed is essential in the postoperative period. If any compromise in circulation is suspected, the surgeon must be notified immediately. Because pulses are not always palpable postoperatively, as a result of vasoconstriction and hypothermia, capillary refill can be used to assess the adequacy of perfusion. Elevation and elastic wrapping of the extremity can help to minimize edema formation, particularly after venous ligation or repair. In these cases, and particularly if a fasciotomy was not performed, the extremity must be evaluated frequently for signs and symptoms of compartment syndrome (discussed later).

Thrombosis of an arterial reconstruction should be suspected when a discrepancy exists between pulses or when the ABI falls to less than 0.9 in the normothermic patient. Although edema is a universal complication, especially after venous ligation, edema may also indicate thrombosis at the site of a venous repair. When present, the surgeon must be identified immediately as these patients may require an immediate return to the operating room to restore perfusion.

Bleeding in the postoperative period may be due to coagulopathy, incomplete ligation of small vessels, or dehiscence of an arterial suture line. Coagulopathy should be reversed with appropriate blood component therapy as guided by coagulation parameters (see Chapter 19). Careful inspection of the wound and estimation of the degree of hemorrhage can often help to differentiate simple wound bleeding from suture line dehiscence.

Graft infection rarely complicates the early postoperative period. Wound infection, however, must be considered in the febrile patient because groin incisions are frequently used for lower-extremity vascular trauma. Proximity of injury to the perineum and interruption of the lymphatics both predispose to infection.

Categories of Nerve Injuries

Injuries to peripheral nerves often accompany vascular trauma and are classified by histologic changes and associated neurologic insults.

Neurapraxia occurs most frequently after blunt trauma and is characterized by local physiologic loss of axonal conduction. Patients typically present with isolated motor paralysis and sparing of sensory and autonomic function. Because the distal axon remains intact and there is preservation of electrical conductivity, full recovery can usually be achieved with conservative management.

Axonotmesis refers to axonal injury with preservation of the endoneurium (connective tissue elements) and occurs most commonly after blunt trauma or traction. Wallerian degeneration produces motor, sensory, and autonomic dysfunction with subsequent distal muscle atrophy. Nerve regeneration occurs at a rate of 1 mm/day. Functional recovery is influenced by age, associated injuries, and the peripheral level of injury (proximal versus distal). Surgery may be indicated for patients who fail to recover function.

Complete or partial transection of the nerve is defined as neurotmesis and is characterized by a complete loss of motor, sensory, and autonomic function and leads to distal muscle atrophy. Lack of connective tissue support can result in misrouting of regenerating nerves and formation of painful neuromas. Surgical intervention is indicated in these patients if they are otherwise expected to have a meaningful overall functional recovery from their other traumatic injuries.