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Orthostatic intolerance after spaceflight
- Source :
- Journal of applied physiology (Bethesda, Md. : 1985). 81(1)
- Publication Year :
- 1996
-
Abstract
- Orthostatic intolerance occurs commonly after spaceflight, and important aspects of the underlying mechanisms remain unclear. We studied 14 individuals supine and standing before and after three space shuttle missions of 9-14 days. After spaceflight, 9 of the 14 (64%) crew members could not complete a 10-min stand test that all completed preflight. Pre- and postflight supine hemodynamics were similar in both groups except for slightly higher systolic and mean arterial pressures preflight in the finishers [15 +/- 3.7 and 8 +/- 1.2 (SE) mmHg, respectively; P < 0.05]. Postflight, finishers and nonfinishers had equally large postural reductions in stroke volume (-47 +/- 3.7 and -48 +/- 3.3 ml, respectively) and increases in heart rate (35 +/- 6.6 and 51 +/- 5.2 beats/min, respectively). Cardiac output during standing was also similar (3.6 +/- 0.4 and 4.1 +/- 0.3 l/min, respectively). However, the finishers had a greater postflight vasoconstrictor response with higher total peripheral resistance during standing (22.3 +/- 1.2 units preflight and 29.4 +/- 2.3 units postflight) than did the nonfinishers (20.1 +/- 1.1 units preflight and 19.9 +/- 1.4 units postflight). We conclude that 1) the primary systemic hemodynamic event, i.e., the postural decrease in stroke volume, was similar in finishers and nonfinishers and 2) the heart rate response and cardiac output during standing were not significantly different, but 3) the postural vasoconstrictor response was significantly greater among the finishers (P < 0.01).
- Subjects :
- Adult
Male
Supine position
Physiology
Posture
Crew
Orthostatic intolerance
Spaceflight
law.invention
Hypotension, Orthostatic
Oxygen Consumption
law
Heart Rate
Physiology (medical)
medicine
Humans
Cardiovascular Deconditioning
Leg
biology
Weightlessness
business.industry
Syncope (genus)
Space medicine
Stroke Volume
Baroreflex
Middle Aged
Space Flight
medicine.disease
biology.organism_classification
Regional Blood Flow
Vasoconstriction
Anesthesia
Female
Vascular Resistance
business
Subjects
Details
- ISSN :
- 87507587
- Volume :
- 81
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Accession number :
- edsair.doi.dedup.....6a38311c654e21497f9c6f110208129d