90 - Arterial and Venous Trauma and Great Vessel Injuries

of great vessel trauma, and any thoracic vascular structure is at risk. Patients who survive to arrive at the emergency department, particularly if they are not in hemorrhagic shock, have a survival rate that approaches 50%. In contrast, blunt traumatic injuries to the great vessels most often affect the aorta, although the innominate artery, pulmonary hilar vessels, and vena cava are also susceptible. Blunt aortic rupture carries an immediate mortality rate of greater than 80% and is responsible for 10% to 15% of motor vehicle accident fatalities. Because of the high association of blunt ascending aortic injury with fatal cardiac injury, the vast majority of those who survive to hospital evaluation have descending injuries. Of patients who survive until medical evaluation, 30% die within 6 hours and 40% within 24 hours. Because most of these injuries occur in young healthy males, the overall survival rate is much better than expected given the severity of injury. Though incompletely understood, it is proposed that blunt aortic injury can result from any combination of shearing forces, rotational forces, increased intraluminal aortic pressure, or a pinching mechanism between the sternum and vertebral column. Given these forces, it is not a surprise that motor vehicle collisions cause the majority of blunt aortic injuries. This association increases with the speed of the accident. Shearing forces were originally thought to be the highest in frontal-impact accidents, where deceleration forces are the greatest. More recent studies, however, have shown that side-impact accidents are associated with a higher risk for blunt aortic injury. A review of 119 cases of known blunt aortic injury as a result of car accidents in the United Kingdom found that lateral impact direction to the same side was highly associated with aortic injury. A review of accident data from the United Kingdom and United States in 2004 mirrored these results and found that side impact involving the patient’s side of the vehicle carried a significantly higher risk for aortic injury than did frontal impact. Although motor vehicle accidents account for the majority of blunt GVI, falls from a height and crushing forces have also been known to cause the disease process. In part because of difficulty isolating the hilum, injuries to the pulmonary arteries, veins, and thoracic vena cava are associated with mortality rates greater than 60%, regardless of whether they are caused by blunt or penetrating force, although the latter is much more common. Concomitant injuries clearly play a role in the epidemiology, morbidity, and mortality of GVI. One study on blunt thoracic trauma showed that patient with traumatic aortic injury carried a mean injury severity score (ISS) of 40 • Thirty percent of patients with great vessel injury (GVI) die within 6 hours of hospital arrival. • Thirty percent to 50% of patients with blunt aortic injury have no signs of trauma. • A normal chest radiograph does not exclude GVI. • Computed tomographic angiography is the diagnostic test of choice to rule out traumatic aortic injury in hemodynamically stable patients. • For patients too large for a computed tomography scanner, transesophageal echocardiographic evaluation of the aorta should be considered. • Medical management of GVI is typically used as a bridge to more definitive operative care. • β-Adrenergic blockade is instituted before nitroprusside in the medical management of GVI to avoid possible reflex tachycardia. KEY POINTS