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Should Head-Injured Patients Be Taken to the Nearest Hospital or to a Hospital with Neurosurgical Capability That Is Farther Away?
BRIEF ANSWER
All patients with severe traumatic brain injury (TBI) [Glasgow Coma Scale (GCS) score ≤8] should be treated according to standard Advanced Trauma Life Support (ATLS) guidelines. Specific attention should be paid to avoiding and treating hypoxia and hypotension. Although no class I evidence exists, ample class II and III evidence supports a level II recommendation to transport patients with severe TBI to definitive care at a hospital with neurosurgical and neurocritical care capabilities.
Background
TBI continues to be the most significant cause of morbidity and mortality in the United States among persons 1 to 44 years of age. Data from 1991 reveal that ~1.5 million people in the United States suffer TBI annually, with over 1.1 million of these patients receiving outpatient care or no care at all and 393,000 being admitted to a hospital (class III data).1 A population-based study from San Diego County revealed that over 40% of all trauma deaths resulted from acute head injury (class III data).2 The loss in potential years of life, productivity, and potential income is enormous. In the U.S. alone, the cost to society was estimated to exceed $40 billion annually in 19663; this figure has increased significantly in the intervening years. Worldwide, TBI is the leading cause of loss of productive years of life from either death or disability.
To reduce the morbidity and mortality associated with TBI, efforts have been made both to improve treatment and, more importantly, to reduce its incidence. In some parts of the United States, legislation to require helmets for motorcycle riders and programs to encourage helmet use among pediatric and adult bicycle riders has been associated with significant decreases in both the proportion of severe head injuries among victims of motorcycle and bicycle crashes and in the mortality associated with these types of accidents (class III data).4
Once TBI has occurred, treatment must focus on the prevention of secondary brain injury (SBI). Although long recognized, the concept of SBI has only recently been formally characterized. As a result of the initial traumatic event, an intracranial hematoma may rapidly enlarge and cause mass effect and midline shift. Hypoxia and hypotension may contribute to ischemia and subsequent edema. Increased intracranial pressure (ICP) from a mass lesion or brain swelling may compromise cerebral blood flow by decreasing cerebral perfusion pressure, placing a patient at risk for cerebral ischemia, subsequent cerebral edema, frank herniation, and death.
Literature Review
What can we learn from the past? Walter B. Cannon was a physiologist who studied the pathophysiology of traumatic shock in soldiers during World War I. Despite austere conditions on the front lines, he was able to make some remarkable observations that remain valid today. The first of these was that the body requires a minimal blood pressure to preserve delivery of oxygen and removal of metabolic waste products. He determined this threshold to be a systolic blood pressure of 80 mmHg. In conjunction with two pathologists, Gomez and Pike, he also analyzed the tolerance for hypoxia of various tissues of the body. He found the nervous system to be the tissue most sensitive to hypoxia and anemia, with as little as 8 minutes of anemia resulting in death of pyramidal cells in the cerebral cortex. Other areas of the nervous system tolerated progressively longer periods of anemia, with the spinal cord tolerating up to 45 to 60 minutes. He concluded, “Injured nerve cells require a better blood supply for their restoration than uninjured cells do for mere maintenance.”5
To accomplish the goals of preserving perfusion pressure and preventing hypoxia, Cannon strongly advocated the use of blood as a resuscitation fluid. Crystalloids could help restore blood pressure only temporarily, and they obviously could not carry oxygen to the tissues. Moreover, salt solutions contributed significantly to third-space fluid losses from increased capillary permeability if treatment had been delayed. Colloids were found to have beneficial effects if used early in those soldiers with mild to moderate injures. For those with serious wounds or for whom treatment was delayed, early surgical intervention to prevent further blood loss prior to resuscitation correlated with a better outcome. Low blood pressure prevented further blood loss for a period of time, but its occurrence placed the patient at increased risk for end-organ damage from hypoperfusion. Therefore, he concluded that blood and salt solutions should be used as temporizing measures to maintain a minimal blood pressure of 80 mmHg to preserve viability of sensitive tissues until definitive surgical care became available.
Pearl
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