The Modulation of Oxygen Toxicity by Intermittent Exposure

Abstract

Intermittent delivery of hyperbaric O2 protects animals from pulmonary and central nervous system toxicity: more total O2 time can be tolerated if interrupted by shore periods of low O2. Hyperbaric O2 is used therapeutically for a variety of clinical disorders, as well as in standard decompression procedures designed to hasten elimination of inert gases. In addition to the pulmonary effects normally associated with normobaric O2 toxicity (tracheobronchial irritation, decrements in vital capacity, pulmonary edema), a variety of central nervous system (CNS) symptons (anxiety and nausea, altered vision and hearing, muscular twitching and paresthesias, unconsciousness, and seizures) will develop with hyperbaric O2 exposure. Because of evidence suggesting that some protection from O2 toxicity may be obtained by intermittency, hyperbaric O2 is often delivered with regular interruptions by a gas of lower PO2. The goal of the present study was to gain increased understanding about the benefits of intermittent hyperbaric O2 exposure by conducting experiments and applying models the results.Pub. in Toxicology and Applied Pharmacology, v93 n2 p298-311 Apr 1988.