Management of Extremity Vascular Trauma

Management of Extremity Vascular Trauma

Sean R. Dariushnia and Curtis A. Lewis

Vascular injury has two main consequences—hemorrhage and ischemia. Or, in the words of an anonymous Czech surgeon, “Bloody vascular trauma—it’s either bleeding too much or it’s not bleeding enough.”¹ Unrecognized and uncontrolled hemorrhage can rapidly lead to a trauma patient’s demise. Unrecognized and untreated ischemia can lead to limb loss, stroke, bowel necrosis, and multiple organ failure. The aim of this chapter is to highlight the fundamentals of peripheral vascular trauma and provide an approach to the diagnosis and management of vascular injury.

Arterial and venous structures are most commonly injured by penetrating trauma, with a much higher incidence in gunshot wounds than for stab injury. Blunt trauma also carries a significant vascular injury rate, and iatrogenic vascular injuries are increasing as radiologic and minimal-access procedures become more commonplace.

Hemorrhage is the prime consequence of vascular injury. Bleeding may be obvious, with visible arterial hemorrhage, or it may be concealed. Classically, concealed arterial hemorrhage may be in the chest, abdomen, and pelvis. Hemorrhage may also be concealed in the soft tissues of the buttock and thigh, and blood from facial fractures may be swallowed and go unnoticed.

Ischemia results from acute interruption of blood flow to a limb or organ. When oxygen supply is inadequate to meet demand, anaerobic metabolism takes over, producing lactic acidosis and activating cellular and humoral inflammatory pathways. If the arterial supply is not reestablished in time, cell death occurs. Skeletal muscle can be rendered ischemic for 3 to 6 hours and still recover function. Peripheral nerves are more sensitive to ischemia, and prolonged neurologic deficit may result from relatively short periods of tissue ischemia.

If arterial supply is restored to ischemic tissue, the sudden release of inflammatory mediators, lactic acid, potassium, and other intracellular material into the circulation can cause profound myocardial depression and generalized vasodilatation and may initiate a systemic inflammatory response.

Vascular trauma can result in serious and potentially fatal consequences. Percutaneous intervention can provide immediate control of hemorrhage and in many cases can be lifesaving.

In addition, definitive long-lasting treatments can be obtained using the percutaneous approach when patients are appropriately selected. In view of the rising number of cases of vascular trauma seen at trauma centers, endovascular therapy has an increasing role in the treatment of traumatic vascular injury.

Indications

Patterns of Vascular Injury

Laceration with either complete or incomplete vessel transection is the most common form of vascular injury. Hemorrhage tends to be more severe in partially transected vessels because complete transection results in retraction and vasoconstriction of the vessel, limiting or even preventing arterial hemorrhage.

Blunt trauma injures vessels by crushing, distraction, or shearing. This results in contusion to the vessel, which may extend for some distance along its length. An intimal flap may be formed that will lead to thrombosis or dissection and subsequent rupture. Thrombosis may propagate for some distance down the vessel, or there may be embolization to produce effects more distally.

Arterial hemorrhage may continue within a contained hematoma, leading to a pulsatile mass, a pseudoaneurysm. Commonly, distal flow is preserved with false aneurysm formation, and diagnosis may be difficult. Aneurysms are at risk of rupture if undiagnosed, and often present late after the initial injury is forgotten.

If there is injury to an adjacent vein as well as to the artery, an arteriovenous fistula (AVF) can form, which may subsequently lead to rupture or cardiovascular compromise. AVFs may present some time after the initial injury.

Spasm as a unique entity is never the result of trauma and should not be assumed to be the cause of limb ischemia.

Hard Signs of Vascular Injury

• Pulsatile bleeding

• Expanding hematoma

• Absent distal pulses

• Cold, pale limb

• Palpable thrill

• Audible bruit

Soft Signs of Vascular Injury

• Peripheral nerve deficit

• History of moderate hemorrhage at the scene

• Reduced but palpable pulse or an injury in proximity to a major artery

• Unexplained hypotension

• Mechanism and location of injury

Equipment

For the diagnosis of arterial injury, no special equipment is required other than what is usually found in the radiology department, such as angiography, ultrasound, computed tomography (CT), and the simple sphygmomanometer.

In the operating room, the surgeon is usually able to provide direct access to the artery, but it is easier and safer to use the Seldinger technique to insert a catheter than via an arteriotomy.

Technique

The diagnosis of significant vascular injury rests almost entirely on the physical examination. An absence of hard signs of vascular injury does not exclude the presence of vascular trauma. In contrast, the presence of hard signs mandates immediate action.

Diagnostic Tests

Pulse Oximetry

A reduction in oximeter readings from one limb as compared with another is suggestive of, but neither confirms nor excludes, a significant vascular injury. It is therefore essentially unhelpful.

Doppler Ultrasonography

The diagnosis of a significant (i.e., requiring intervention) vascular injury relates to the presence or absence of a palpable pulse. Presence of a Doppler signal in a pulseless limb only gives a false sense of security and does not imply a less severe or less urgent injury pattern. A diminished but palpable pulse is a soft sign of vascular injury.

Similarly, a reduction in the ankle-brachial pressure index in the presence of a palpable pulse does indicate the presence of a vascular injury requiring intervention. A differential in peak systolic cuff pressures between the traumatized and normal extremity predicts a significant (requiring repair) vascular injury at angiography. This was clearly demonstrated in 1993 by Schwartz and Weaver, who entered over 500 consecutive patients with isolated upper or lower extremity penetrating injury into a prospective study designed to refine the indications for diagnostic arteriography. Fourteen major injuries and 10 nonocclusive injuries were identified. Only pulse deficit (P < .01) and an ankle-brachial or wrist-brachial index less than 1.00 in the injured extremity (P < .03) were found to be significant predictors of an arterial injury.² Doppler sonography alone, therefore, adds little to careful clinical examination.

Duplex Ultrasonography

Duplex imaging is a noninvasive examination combining B-mode and Doppler ultrasonography. It requires an experienced operator and is very operator dependent. Duplex ultrasonography can detect intimal tears, thrombosis, false aneurysms, and AVFs. Its place in the assessment of vascular injury not yet completely defined, but it has a high sensitivity and may be appropriate for use as a screening tool. However, equipment and, more specifically, a skilled operator may not always available after hours and on weekends.

Computed Tomographic Angiography

CT scanners are present in nearly every hospital. In trauma centers, 16- and 64-MDCT technology is commonplace and allows for fast image acquisition of the entire body (seconds). Routinely, if the patient presents with polytrauma and is hemodynamically stable, a head, chest, and abdomen/pelvis CT (PAN-SCAN) can be obtained. With multidetector scanners, an extremity computed tomographic angiography (CTA) examination can easily be added to the PAN-SCAN with the same contrast injection, without significantly adding to image acquisition time.³ Axial images can be viewed immediately after image acquisition and most injuries identified. Postprocessing three-dimensional (3D) reconstructions can provide an easily understandable format obtainable within minutes of the scan and can be of benefit to both the radiologist and nonradiologist clinician, especially the vascular or trauma surgeon (Fig. 39-1).

FIGURE 39-1 Traumatic pseudoaneurysm. Patient with history of gunshot wound to right upper extremity. Computed tomographic angiogram was initially obtained. Axial (A), sagittal (B), and coronal (C) thin-slice images demonstrate luminal irregularity and extraluminal contrast involving right axillary artery, consistent with pseudoaneurysm. D, Coronal maximum intensity projection (MIP) shows pseudoaneurysm to better advantage.

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Tags: Image-Guided Interventions Expert Radiology Series

Dec 23, 2015 | Posted by admin in INTERVENTIONAL RADIOLOGY | Comments Off

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