MODERATE HYPOTHERMIA IN PATIENTS WITH SEVERE HEAD-INJURY - CEREBRAL AND EXTRACEREBRAL EFFECTS

Cerebral and extracerebral effects of moderate hypothermia (core tempe rature 32.5 degrees C-33.0 degrees C) were prospectively studied in 10 patients with severe closed head injury (Glasgow Coma Scale score < 7 ) in the intensive care unit of a university hospital. Hypothermia was induced by cooling the patient's body surface with water-circulating blankets. Before cooling, a conventional intracranial pressure (ICP) r eduction therapy was applied, which remained unchanged throughout the study. Cerebral blood flow (CBF), cerebral metabolic rates for oxygen (CMRO(2)) and lactate (CMRL), and ICP were simultaneously measured pri or to inducing hypothermia, after obtaining hypothermia. after 24 hour s of hypothermia, and after rewarming. With respect to extracerebral e ffects, supplemental investigations were conducted 24 and 72 hours aft er rewarming. The median delay between injury and induction of hypothe rmia was 16 hours. Hypothermia reduced CMRO(2) by 45% (p < 0.01), wher eas CBF did not change significantly. Before cooling, six patients had elevated CMRL indicating cerebral ischemia. Cooling normalized CMRL i n all patients (p < 0.01). The intracranial hypertension present prior to cooling declined markedly during hypothermia (p < 0.01) without si gnificant rebound effects after rewarming. Cardiac index decreased by 18% after hypothermia was reached (p < 0.05), recovered at 24 hours of hypothermia, and surpassed baseline values after rewarming. Platelet counts dropped continuously up to 24 hours after rewarming (p < 0.01). Plasma coagulation tests did not show significant worsening. Creatini ne clearance decreased during cooling (p < 0.01) and recovered by 24 h ours after rewarming. Twenty-four hours after cooling had begun, eight patients had elevated serum lipase activity (p < 0.01) and four of th em acquired pancreatitis. Rewarming normalized both pancreatic alterat ions. Seven patients made a good recovery; one survived severely disab led; and two patients died. Moderate hypothermia is effective in preve nting secondary brain damage while reducing cerebral ischemia. However , there are potentially hazardous side effects that require additional monitoring.