The protective action of certain anaesthetics and tranquilizers against the effects of hyperbaric oxygen.

The protective effects of pentobarbitone, hydroxydione and diazepam against acute and chronic toxicity of high-pressure oxygen (HPO) were studied in rats. During exposure to hyperbaric oxygen body temperature was measured and ECG as well as EMG tracings from the diaphragm were obtained. Long term observations of animals after the exposure to HPO were conducted. Pentobarbitone and hydroxydione reduced the manifestations of acute toxicity but increased those of chronic toxicity. Diazepam reduced the manifestations of acute toxicity and seemed to counteract those of chronic toxicity. Lowering of body temperature of the animals which occurred during exposure to HPO was probably connected with manifestations of chronic toxicity. Observation of the cardiorespiratory functions suggested a possible connection between their disturbances and an onset of seizures and development of oxygen-induced paralysis.