The Responses of an Awake Brain to HPO Under Increased CO₂ Concentrations

Abstract

The interrelations between convulsive activity, and CO₂ concentration under hyperbaric oxygen conditions were investigated by few investigators. It was shown in mice (Marshall and Lambertsen, 1961) and in cats (Taylor, 1949) that small elevation of CO₂ under HPO, potentiated the toxicity phenomenon while higher levels of CO₂ inhibited convulsions. Other investigators (Levy and Richards, 1962) came to the conclusion that addition of CO₂ to the HPO chamber provided the animal with protection against toxicity. In our previous communication (Mayevsky et al., 1974) we found that 1.5% CO₂ in oxygen potentiates the toxicity under pressure of 6 ATA. In order to understand the effects of CO₂ on the response of the brain to HPO we measured the effects of various concentrations of CO₂ on the electrical activity as well as the metabolic activity of the awake brain.