Mild hypothermia prevents cerebral edema and CSF lactate accumulation in acute liver failure

Evidence from both clinical and experimental studies demonstrates that mild hypothermia prevents encephalopathy and brain edema in acute liver failure (ALF). As part of a series of studies to elucidate the mechanism(s) involv ed in this protective effect, groups of rats with ALF resulting from hepati c devascularization were maintained at either 37 degreesC (normothermic) or 35 degreesC (hypothermic), and neurological status was monitored in relati on to cerebrospinal fluid (CSF) concentrations of ammonia and lactate. CSF was removed via implanted cisterna magna catheters. Mild hypothermia result ed in a delay in onset of encephalopathy and prevention of brain edema; CSF concentrations of ammonia and lactate were concomitantly decreased. Blood ammonia concentrations, on the other hand, were not affected by hypothermia in ALF rats. These findings suggest that brain edema and encephalopathy in ALF are the consequence of ammonia-induced impairment of brain energy meta bolism and open the way for magnetic resonance spectroscopic monitoring of cerebral function in ALF. Mild hypothermia could be beneficial in the preve ntion of severe encephalopathy and brain edema in patients with ALF awaitin g liver transplantation.