Hyperbaric oxygen and pulmonary surface tension.

Abstract

Previous work has shown that short-term exposure of cats to oxygen at high pressure (OHP), to the extent of overt convulsive seizures, has little or no effect on the lung appearance or lung weight but does alter the alveolar surfactants. More prolonged exposure results in hemorrhagic edema of the cat lung similar to that observed in rats after only short-term exposure. Previous work showed that sympathetic stimulation via the stellate ganglion and mechanical CNS injury results in altered surfactants attributed to increased intra-alveolar cholesterol. In the present study, cats exposed to OHP until the animals convulsed intermittently for 3 min (approximately 1 hour, 6 ATA) similarly showed altered surfactants with a high minimum surface tension and a 150% increase in intra-alveolar cholesterol. These changes also occurred in the absence of any gross lung injury. The results from the present study suggest that an important causal mechanism involved in the development of gross lung injury associated with prolonged OHP exposure is an initial increase in minimum surface tension due to increased intra-alveolar cholesterol.