Pulmonary function in men after oxygen breathing at 3.0 ATA for 3.5 h.
As a pulmonary component of Predictive Studies V, designed to determine O2 tolerance of multiple organs and systems in humans at 3.0-1.5 ATA, pulmonary function was evaluated at 1.0 ATA in 13 healthy men before and after O2 exposure at 3.0 ATA for 3.5 h. Measurements included flow-volume loops, spirometry, and airway resistance (Raw) (n = 12); CO diffusing capacity (n = 11); closing volumes (n = 6); and air vs. HeO2 forced vital capacity maneuvers (n = 5). Chest discomfort, cough, and dyspnea were experienced during exposure in mild degree by most subjects. Mean forced expiratory volume in 1 s (FEV1) and forced expiratory flow at 25-75% of vital capacity (FEF25-75) were significantly reduced postexposure by 5.9 and 11.8%, respectively, whereas forced vital capacity was not significantly changed. The average difference in maximum midexpiratory flow rates at 50% vital capacity on air and HeO2 was significantly reduced postexposure by 18%. Raw and CO diffusing capacity were not changed postexposure. The relatively large change in FEF25-75 compared with FEV1, the reduction in density dependence of flow, and the normal Raw postexposure are all consistent with flow limitation in peripheral airways as a major cause of the observed reduction in expiratory flow. Postexposure pulmonary function changes in one subject who convulsed at 3.0 h of exposure are compared with corresponding average changes in 12 subjects who did not convulse.
Clark
J M
JM
Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia 19104-6068.
Jackson
R M
RM
Lambertsen
C J
CJ
Gelfand
R
R
Hiller
W D
WD
Unger
M
M
D000328:Adult; D006801:Humans; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D008168:Lung / Q000502:physiology*; D008176:Lung Volume Measurements; D008297:Male; D010100:Oxygen / Q000633:toxicity*; D012129:Respiratory Function Tests; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology; D013147:Spirometry; D013997:Time Factors
D010100:Oxygen