Pulmonary atelectasis in subjects breathing oxygen at sea level or at simulated altitude.

Abstract

Seven subjects were exposed to atmospheres of 100% O2 at 5 psi, 72 hr; 7.5 psi, 72 hr; or 14.7 psi (sea level), 24 hr. Four of these developed a decrease of vital capacity, and of these 4, 2 had plate-like atelectasis by X-ray. One of these was re-exposed to mixtures of O2 with 30%, 5%, or 2.5% N2 at 5 psi. The first 2 mixtures prevented the X-ray and vital capacity changes from occurring, whereas the 3rd did not. In this subject there appeared to be air trapping as indicated by lateral displacement of the airway conductance-lung volume curve. It is concluded that absorptional atelectasis which occurred while breathing O2 could be prevented in this subject by adding 5-30% N2 to the O2.