101. An optimized index of human cardiovascular adaptation to simulated weightlessness
- Author
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Wang, Mao, Hassebrook, Laurence, Evans, Joyce, Varghese, Tomy, and Knapp, Charles
- Subjects
Weightlessness -- Physiological aspects ,Cardiovascular system -- Physiological aspects ,Adaptation (Physiology) -- Measurement ,Discriminant analysis -- Usage ,Biological sciences ,Business ,Computers ,Health care industry - Abstract
Prolonged exposure to weightlessness is known to produce a variety of cardiovascular changes, some of which may influence the astronaut's performance during a mission. In order to find a reliable indicator of cardiovascular adaptation to weightlessness, we analyzed data from nine male subjects after a 24-hour period of normal activity and after a period of simulated weightlessness produced by two hours in a launch position followed by 20 hours of 6 [degrees] head-down tilt plus pharmacologically induced diuresis (furosemide). Heart rate, arterial pressure, thoracic fluid index, and radial flow were analyzed. Autoregressive spectral estimation and decomposition were used to obtain the spectral components of each variable from the subjects in the supine position during pre- and post-simulated weightlessness. We found a significant decrease in heart rate power and an increase in thoracic fluid index power in the high frequency region (0.2-0.45 Hz) and significant increases in radial flow and arterial pressure powers in the low frequency region (
- Published
- 1996