Delayed evaluation of combat-related penetrating neck trauma.

OBJECTIVE: The approach to penetrating trauma of the head and neck has undergone significant evolution and offers unique challenges during wartime. Military munitions produce complex injury patterns that challenge conventional diagnosis and management. Mass casualties may not allow for routine exploration of all stable cervical blast injuries. The objective of this study was to review the delayed evaluation of combat-related penetrating neck trauma in patients after evacuation to the United States. METHOD: From February 2003 through April 2005, a series of patients with military-associated penetrating cervical trauma were evacuated to a single institution, prospectively entered into a database, and retrospectively reviewed. RESULTS: Suspected vascular injury from penetrating neck trauma occurred in 63 patients. Injuries were to zone II in 33%, zone III in 33%, and zone I in 11%. The remaining injuries involved multiple zones, including the lower face or posterior neck. Explosive devices wounded 50 patients (79%), 13 (21%) had high-velocity gunshot wounds, and 19 (30%) had associated intracranial or cervical spine injury. Of the 39 patients (62%) who underwent emergent neck exploration in Iraq or Afghanistan, 21 had 24 injuries requiring ligation (18), vein interposition or primary repair (4), polytetrafluoroethylene (PTFE) graft interposition (1), or patch angioplasty (1). Injuries occurred to the carotid, vertebral, or innominate arteries, or the jugular vein. After evacuation to the United States, all patients underwent radiologic evaluation of the head and neck vasculature. Computed tomography angiography was performed in 45 patients (71%), including six zone II injuries without prior exploration. Forty (63%) underwent diagnostic arteriography that detected pseudoaneurysms (5) or occlusions (8) of the carotid and vertebral arteries. No occult venous injuries were noted. Delayed evaluation resulted in the detection of 12 additional occult injuries and one graft thrombosis in 11 patients. Management included observation (5), vein or PTFE graft repair (3), coil embolization (2), or ligation (1). CONCLUSIONS: Penetrating multiple fragment injury to the head and neck is common during wartime. Computed tomography angiography is useful in the delayed evaluation of stable patients, but retained fragments produce suboptimal imaging in the zone of injury. Arteriography remains the imaging study of choice to evaluate for cervical vascular trauma, and its use should be liberalized for combat injuries. Stable injuries may not require immediate neck exploration; however, the high prevalence of occult injuries discovered in this review underscores the need for a complete re-evaluation upon return to the United States.

Learning and memory is preserved after induced asanguineous hyperkalemic hypothermic arrest in a swine model of traumatic exsanguination.

BACKGROUND: Induced asanguineous hypothermic metabolic arrest (suspended animation) could provide valuable time to repair major vascular injuries if safely induced in patients with trauma. We report a novel method of doing this in a swine model of uncontrolled lethal hemorrhage (ULH) that resulted in preservation of learning ability and memory. METHODS: Yorkshire swine (100 to 125 lb) underwent ULH before rapid intra-aortic infusion of a hypothermic (4 degrees C), hyperkalemic (70 mEq/L) organ preservation solution by a left thoracotomy. Cooling continued until core temperature reached 10 degrees C, and this was maintained for 60 minutes using low-flow cardiopulmonary bypass. Vascular injuries were repaired during this state of suspended animation, which was then reversed, and the animals were observed for 6 weeks. Cognitive functions were tested by training animals to retrieve food from color-coded boxes. Postoperatively, the ability to remember this task and a 75-point objective neurologic scale were used to test neurologic function. In experiment I, ULH was caused by lacerating thoracic aorta (n = 9). Five preoperatively untrained animals were trained to perform the task and compared with control animals (n = 15), and 4 preoperatively trained animals were tested for memory retention postoperatively. In experiment II, ULH was induced by creating an iliac artery and vein injury (n = 15). Animals were kept in shock for 15, 30, and 60 minutes before the induction of hypothermia. RESULTS: In experiment I, surviving animals (7/9) were neurologically intact, and their capacity to learn new skills was no different than for control animals. All pretrained animals demonstrated complete memory retention. In experiment II, survival with 15, 30, and 60 minutes of shock were 80%, 60%, and 80%, respectively. All animals (except 1) in the 60-minute group were neurologically intact and displayed normal learning capacity. CONCLUSIONS: Induction of hypothermic metabolic arrest (by thoracotomy) for repair of complex traumatic injuries is feasible with preservation of normal neurologic function, even after extended periods of shock from an intra-abdominal source of uncontrolled hemorrhage.