The effects of increased oxygen concentrations and acceleration forces on the mechanical properties of the lungs

Abstract

The effects of breathing increased concentrations of oxygen (FI0₂ of 0.6 to 1.0) on the pulmonary compliance and pulmonary resistance were examined in normal, seated males. Exposures were for one hour and volume history of the lungs was established a t 10 minute intervals. There were no significant changes in any of the parameters examined. In addition, the effects of breathing increased oxygen concentrations (FI0₂'s of 0.6 to 0.8) and exposure to increased acceleration forces (+5Gz for 120 seconds and +7Gz for 45 seconds) on pulmonary compliance and resistance were examined in normal, seated males. Pulmonary compliance decreased significantly in subjects breathing the increased FI0₂'s after exposure to acceleration forces when compared to room air controls. The decrease in compliance appeared to be a function of the FI0₂, with those subjects breathing the greater FI0₂ showing a greater decrease in compliance than those subjects breathing the lesser FI0₂. There was no significant difference in the degree of compliance decrease between the two acceleration levels for a particular FI0₂. The pulmonary compliance showed a gradual return towards the pre-acceleration exposure level during the 15 minute interval between acceleration force exposures.