Abstract
Background: Most anesthetics affect cerebral blood flow and metabolism. We compared microregional O-2 balance in cerebral ischemia-reperfusion during pentobarbital and isoflurane anesthesia. Methods: After 1 hour of middle cerebral artery occlusion and a 2-hour reperfusion under isoflurane (1.4%, n = 14) or pentobarbital (50 mg/kg, n = 14) anesthesia in rats, regional cerebral blood flow using C-14-iodoantipyrine autoradiography, microregional arterial and venous O-2 saturation (20-60 mu m in diameter) using cryomicrospectrophotometry, and the size of cortical infarct were determined. Results: Ischemia-reperfusion decreased the average cortical venous O-2 saturation in both pentobarbital and isoflurane groups (P < .0001), which was higher (P < .05) with pentobarbital despite a similar average regional cerebral blood flow and O-2 consumption. The heterogeneity of venous O-2 saturation reported as a coefficient of variation (100 x standard deviation/ mean) was smaller (P < .005) with pentobarbital than that with isoflurane (7.5 versus 16.1). The number of veins with low venous O-2 saturation (<50%) was smaller (P < .005) with pentobarbital (5 of 80 versus 24 of 80). The percentage of cortical infarct in total cortex was smaller with pentobarbital (5.2 +/- 2.5% versus 12.3 +/- 2.6%, P < .001). Conclusions: In the cerebral ischemic-reperfused cortex, the average venous O-2 saturation was higher, and its heterogeneity and the number of veins with low O-2 saturation were smaller under pentobarbital than isoflurane anesthesia. This improvement in microregional O-2 balance with pentobarbital was accompanied by the reduced cortical infarct. Our data suggest that the neurologic outcome could vary during cerebral ischemia-reperfusion depending on the anesthetics used.