The effect of halothane and isoflurane on neurologic outcome following incomplete cerebral ischemia in the rat.

The relation between sympathetic activity and neurologic outcome was evaluated during fentanyl/nitrous oxide (N2O) (25 micrograms.kg-1.min-1 plus 70% N2O in oxygen), halothane (1.1% inspired), and isoflurane (1.4% anesthesia in a rat model of incomplete cerebral ischemia. Ischemia was produced by right carotid ligation combined with hemorrhagic hypotension to 30 mm Hg for 30 min. Plasma catecholamines were measured during ischemia. Neurologic outcome was measured for 3 days following incomplete ischemia. Both halothane and isoflurane decreased plasma catecholamines 50-80% and improved ischemic outcome compared to fentanyl/N2O anesthesia (P < 0.05). These results indicate a relation between the ability of inhaled anesthetics to decrease sympathetic activity and to improve outcome from incomplete cerebral ischemia.