Arteries, veins, nerves, bones, and soft tissues are at risk with missile injuries to the extremities. ( CD Fig.,u.re...10 and CD Fi9.yie...ll) If the physical examination identifies pulsatile bleeding, expanding hematoma, thrills, bruits, or distal ischemia, exploration is required. These 'hard' physical signs are 99 per cent accurate for arterial injury. Physical examination is less accurate when pulses are palpable, as up to one-third of patients with arterial injury have a normal vascular examination. Diminished pulses or proximity to a major vessel mandates determination of arterial pressure indices using Doppler flow ultrasonography. A standard sphygmomanometer cuff is placed just above the ankle or wrist on the injured extremity and inflated until flow is occluded. The cuff is slowly deflated until a hand-held Doppler instrument detects flow in the vessels distal to the cuff, and this initial pressure is recorded. Measurements should be obtained from the posterior tibial and dorsal pedal arteries of a patient with an injured lower extremity and from the radial and ulnar arteries if the upper extremity has been wounded. A ratio is then calculated between the pressures in the suspect extremity and a similarly obtained pressure in an uninvolved brachial artery. An index of below 0.9 suggests arterial injury, and an arteriogram or exploration should be considered. Duplex scanning is accurate in assessing injury, but its availability limits its usefulness in emergency situations. The arteriogram remains the standard for diagnosing arterial injury but is rarely needed in penetrating extremity trauma. An arteriogram's main utility is to determine the level of injury in patients with multiple potential lesions (shotgun wounds) or a long tract. Arteriography may reveal minor injuries including small pseudoaneurysms, intimal defects, minor branch occlusions, and spasm which may be treated by interventional techniques, obviating the need for surgery. Because of the possibility of bullet emboli, the entire extremity must be assessed. Chest radiographs are obtained in cases of suspicious vascular injury to evaluate for embolization to the lungs, or in rare cases to the heart or arterial system via a patent foramen ovale. An algorithm for the assessment of extremity arterial injury is shown in Fig.Z
CD Figure 10. This young male presented with gunshot wounds to the thigh and popliteal area. The entrance (a) and exit (b) wounds of the lower injury are shown. The patient's foot showed evidence of vascular insufficiency, but it was unclear whether the the superficial femoral vessel or the popliteal vessel or both were injured. An arteriogram (c) revealed popliteal occlusion. Venous injury is often associated. Immediate operative repair is neded to salvage the extremity.
CD Figure 11. This young male suffered a gunshot wound to the proximal upper extremity. No evidence of ischemia was noted on clinical examination. Arterial pressure indices were obtained and measured to be 0.70 when referenced to the uninjured side. A subsequent arteriogram revealed a pseudoaneurysm of the brachial artery which was operatively repaired.
Fig. 2 An algorithm for extremity arterial injury emphasizes early operative exploration for obvious injuries. Arterial pressure indices determine which patients with equivocal examinations or proximity injuries require angiography. Arteriogram or operation remains the standard for defining the injury.
Traumatized extremities are at risk of compartment syndrome. The first signs are a tense calf and pain on passive stretch. The initial symptoms are usually paresthesias. Diagnosis should be made before the 'six Ps' of paresthesia, pain, pallor, paralysis, poikilothermia, and pulselessness are evident. Measurement of extremity compartment pressures using a modified arterial line or self-contained instrument suggests the diagnosis if values are in excess of 30 mmHg. Early fasciotomy prevents further injury secondary to pressure-induced ischemia. When a missile injury results in compartment syndrome without associated fracture, arterial injury is assumed and exploration performed.
Massive tissue destruction by shotgun injuries, blast injuries, or high-velocity weapons requires operative debridement and removal of the wadding of the shotgun shell. Fractures are immobilized and evaluated with appropriate radiographs. Open fractures are contaminated and must be treated with irrigation, debridement, and antibiotics. Nerve injuries can be diagnosed by physical examination in conscious patients. Acute nerve injury secondary to ballistic injury is not addressed immediately. Six weeks is given to allow the neuropraxia to resolve before repair is attempted. Massive extremity injury with arterial, venous, neural, and bony injuries are deemed non-viable, and primary amputation should be performed as the mangled extremity predisposes to the systemic inflammatory response.
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