Human Performance and Acute Hypoxia. Chapter 12
Abstract
The effects of a reduction in ambient oxygen pressure occurring within four hours are dependent to a large extent on one principal factor: the degree of hypoxia and the resultant arterial hypoxemia. As the degree of hypoxia increases, a series of compensatory responses occur in various organ systems which are directly proportional to the severity. Above approximately 1500 m, demonstrable changes become evident in ventilation, cardiac output, circulation, blood endocrine levels, and sensory and mental function. With a level of hypoxia equivalent to approximately 4000 m, the changes can become considerable and can be discerned for almost any physiological and psychological function. The problems are further accentuated when exercise is superimposed on the hypoxia. With physical performance, reductions of both maximal and endurance exercise capacity are observed almost immediately due to the reduction in oxygen content of arterial blood despite potentially beneficial changes in alveolar ventilation, distribution of ventilation/perfusion ratios, cardiac output distribution, shifts in the oxygen-dissociation curve, increases in sympathetic nervous system activity, and changes in fluid control hormones. Keywords: Altitude; Hypoxia; Ventilation; Oxygen transport; Vision; Catecholamines.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1987
- Accession Number
- ADA192604
Entities
People
- Allen Cymerman
- Charles S. Fulco
Organizations
- United States Army Research Institute of Environmental Medicine