Traumatic brain injury, hemorrhagic shock, and fluid resuscitation: effects on intracranial pressure and brain compliance.

Intracranial hypertension following traumatic brain injury is associated with considerable morbidity and mortality. Hemorrhagic hypovolemia commonly coexists with head injury in this population of patients. Therapy directed at correcting hypovolemic shock includes vigorous volume expansion with crystalloid solutions. It is hypothesized that, following traumatic brain injury, cerebrovascular dysfunction results in rapid loss of brain compliance, resulting in increased sensitivity to cerebrovascular venous pressure. Increased central venous pressure (CVP) occurring with vigorous crystalloid resuscitation may therefore contribute to the loss of brain compliance and the development of intracranial hypertension. The authors tested this hypothesis in miniature swine subjected to traumatic brain injury, hemorrhage, and resuscitation. Elevated CVP following resuscitation from hemorrhage to a high CVP significantly worsened intracranial hypertension in animals with concurrent traumatic brain injury, as compared to animals subjected to traumatic brain injury alone (mean +/- standard error of the mean: 33.0 +/- 2.0 vs. 20.0 +/- 2.0 mm Hg, p < 0.05) or to animals subjected to the combination of traumatic brain injury, hemorrhage, and resuscitation to a low CVP (33.0 +/- 2.0 vs. 24.0 +/- 2.0 mm Hg, p < 0.05). These data support the hypothesis that reduction in brain compliance can occur secondary to elevation of CVP following resuscitation from hemorrhagic shock. This may worsen intracranial hypertension in patients with traumatic brain injury and hemorrhagic shock.