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Hypoxic ventilatory sensitivity in men is not reduced by prolonged hyperoxia (Predictive Studies V and VI)Potential adverse effects on the O2-sensing function of the carotid body when its cells are exposed to toxic O2 pressures were assessed during investigations of human organ tolerance to prolonged continuous and intermittent hyperoxia (Predictive Studies V and VI). Isocapnic hypoxic ventilatory responses (HVR) were determined at 1.0 ATA before and after severe hyperoxic exposures: 1) continuous O2 breathing at 1.5, 2.0, and 2.5 ATA for 17.7, 9.0, and 5.7 h and 2) intermittent O2 breathing at 2.0 ATA (30 min O2-30 min normoxia) for 14.3 O2 h within 30-h total time. Postexposure curvature of HVR hyperbolas was not reduced compared with preexposure controls. The hyperbolas were temporarily elevated to higher ventilations than controls due to increments in respiratory frequency that were proportional to O2 exposure time, not O2 pressure. In humans, prolonged hyperoxia does not attenuate the hypoxia-sensing function of the peripheral chemoreceptors, even after exposures that approach limits of human pulmonary and central nervous system O2 tolerance. Current applications of hyperoxia in hyperbaric O2 therapy and in subsea- and aerospace-related operations are guided by and are well within these exposure limits.
Document ID
20040172801
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Gelfand, R.
(Institute for Environmental Medicine, University of Pennsylvania Medical Center Philadelphia 19104-6068, United States)
Lambertsen, C. J.
Clark, J. M.
Hopkin, E.
Date Acquired
August 22, 2013
Publication Date
January 1, 1998
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 84
Issue: 1
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
Clinical Trial
NASA Discipline Cardiopulmonary
Non-NASA Center

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