Anticonvulsant Threshold of CO2 in Oxygen under High Pressure

Abstract

Summary1. A series of 68 mice was exposed to 5 atmospheres of oxygen in a small pressure chamber. Some of these received pure oxygen while others received mixtures of oxygen diluted with varying quantities of CO2. All mice receiving only pure oxygen convulsed. All mice receiving less than 120 mm PCO2 in OHP convulsed. One half of the mice receiving 120 mm PCO2 in OHP convulsed. The other half went on to die without convulsions. Only one out of 17 mice receiving over 120 mm PCO2 convulsed. 2. Mice receiving oxygen diluted with CO2 convulsed sooner than mice receiving pure oxygen. Amount of shortening of convulsion time did not appear to be dependent upon amount of CO2 diluting the oxygen as long as PCO2 lay in the range of 27-120 mm. Both of these findings confirm those of Taylor(l). The tension at which CO2 becomes anticonvulsant appears to be about 120 mm. or about 16% of 1 atmosphere.