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Post-spaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Waters, Wendy W. Ziegler, Michael G. Meck, Janice V. |
| Copyright Year | 2001 |
| Description | About 20% of astronauts suffer post-spaceflight presyncope, but the underlying etiology remains elusive. We studied responses to standing in 36 astronauts before and after spaceflight (5- 16 days). Individuals were separated into presyncopal women, presyncopal men, and non-presyncopal men based on their ability to stand for 10 min postflight. Preflight, presyncopal women and presyncopal men had low vascular resistance, with the women having the lowest. Postflight, women experienced significantly higher rates of presyncope (P<0.01) and significantly greater losses of plasma volume than the men (P<0.05). Both presyncopal women and men had lower standing arterial pressure (P<=0.001) and vascular resistance (P<0.05), smaller increases in norepinephrine (P<=0.058) and greater increases in epinephrine (P<=0.058) than nonpresyncopal men. Both presyncopal groups had a strong dependence (P<=0.05) on plasma volume to maintain standing stroke volume. These findings suggest that postflight presyncope is ascribed to a combination of inherently low resistance responses, a strong dependence on volume status, and spaceflight-induced hypoadrenergic responses. In contrast, high vascular resistance and spaceflight-induced hyperadrenergic responses prevent presyncope. |
| File Size | 12469794 |
| Page Count | 36 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20100033503 |
| Archival Resource Key | ark:/13960/t7wm67f5d |
| Language | English |
| Publisher Date | 2001-01-01 |
| Access Restriction | Open |
| Subject Keyword | Aerospace Medicine Cardiovascular System Epinephrine Physiological Effects Gravitational Physiology Hypotension Stroke Volume Dizziness Etiology Norepinephrine Astronauts Females Orthostatic Tolerance Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
