A 25-year-old male is involved in a motor vehicle accident with a significant head injury. Which of the following statement(s) is/are true concerning his injury and management?

a. A single episode of systolic blood pressure < 90 mm Hg occurring during the early period after injury significantly increases the chances of mortality and morbidity

Brain injury is the most common cause of death in trauma victims, accounting for about half of deaths at the accident site. The injuries are generally the result of blunt trauma, and motor vehicle accidents are the most frequent cause. Head injuries involve not only the primary injury but secondary injuries which can result from the events occurring after the primary insult, due to either the direct consequences of a process initiated by the primary injury or to deleterious outside influences. The occurrence and magnitude of secondary insults is often the determining factor in outcome from brain injury. Since secondary insults, in contrast to primary injuries, are amenable to medical therapy, they are the focus toward which the medical treatment of brain injury is directed. The primary external secondary injury processes occurring following brain injury are hypotension and hypoxia. Hypotension is the number one treatable determinant of severe head injury. A single episode of systolic blood pressure less than 90 mm Hg occurring during the period from injury through resuscitation doubles the mortality and significantly increases the morbidity of any given brain injury. Intracranial hypertension may be considered as being deleterious via two somewhat separate mechanisms—herniation and ischemia. Herniation occurs when a pressure gradient exists across an incomplete barrier such as the tentorium or the falx cerebri. It is deleterious because of the tissue damage that results when herniation occurs. The second aspect of the intracranial hypertension that is deleterious is elevated resistance to cerebral blood flow, resulting in or exacerbating ischemia. Treatment of systemic hypertension is rarely indicated in the head injured patient. There is no evidence that hypertension promotes continued intracranial hemorrhage, and hypertension related to brain injury generally resolves when the intracranial hypertension is controlled. The treatment of intracranial hypertension involves elevating the head of the bed (reversed Trendelenburg position) but should only be performed after complete resuscitation has been accomplished. The confusion and agitation often attendant to head injury renders sedation desirable, therefore, patients with suspected head injury should generally be sedated. Pharmacologic relaxation, however, has the notable effect of limiting the neurologic examination to the pupils and, upon arrival to the hospital, the computed tomography scan. Therefore, its use in the absence of evidence of herniation should be limited to situations which sedation alone is not sufficient to optimize safe and efficient patient transport and resuscitation. When used, short acting agents are strongly preferred. Prophylactic administration of mannitol is not recommended due to volume depleting diuretic effect. In addition, although it is desirable to approximate the lower end of the normal range of PaCO2 during transport of a patient with suspected brain injury, the risk of exacerbating early ischemia by vigorous hyperventilation outweighs the questionable benefit in the patient without evidence of herniation. Therefore, ventilatory parameters consistent with optimal oxygenation and “normal” ventilation are recommended.