Cerebral Oxygen Tension and Microcirculation in Barbiturate Treatment. An Experimental Investigation

The results of barbiturate treatment after acute brain injury are encouraging. To elucidate the mechanism of barbiturate action, direct measurement of oxygen pressure in tissue (tpO2) offers new possibilities. Neither the venous pO2 nor the arterio-venous pO2 difference are reliable values for the determination of brain oxygenation (6, 7). Only the measurement of tpO2 in situ and the calculation of pO2-histo-grams provides a good estimate of tissue oxygen supply. Therefore we used an eight channel surface-microelectrode (produced by Eschweiler, Kiel) (6). Looking at the rates of O2 disappearance, after an externally induced total arrest of cerebral blood flow, allows direct conclusions to be drawn regarding the O2 metabolism (9). Moreover, with the help of a H2 clearance technique a simultaneous determination of local cerebral blood flow becomes possible (2, 10).