Effect of Prophylactic Hyperventilation on Outcome in Patients with Severe Head Injury

Abstract

Severe head injury remains a major problem despite advances in recent years. The mortality of patients with a coma score of eight or less is still between 45–55% (Miller et al. 1981). In an attempt to improve outcome in a significant number of these patients, we have directed our efforts toward therapeutically influencing the brain and its environment after a severe head injury. Severe mechanical brain injury initiates a series of complex events in the brain which are thought to secondarily influence the ultimate outcome of the patient. One of these proposed secondary events is cerebral acidosis. The presence of cerebral acidosis has been inferred by the presence of lactate in ·the CSF of patients sustaining a severe mechanical brain injury (Cold et al. 1975, Enevoldsen et al. 1977, Sood et al. 1980). In addition, prognostic significance has been attached to high levels of lactate in the CSF after a severe brain injury (Crockard et al. 1972; Seitz and Ocker 1977). Furthermore, it has been shown that acidosis itself, when present as the result of any pathologic process, is harmful to the brain (Pulsinelli and Petito 1983). It was felt therefore that outcome from severe head injury might be improved if cerebral acidosis present after a head injury was treated.