Orthostatic intolerance after spaceflight

Jay C. Buckey, Lynda D. Lane, Benjamin D. Levine, Donald E. Watenpaugh, Sheryl J. Wright, Willie E. Moore, F. Andrew Gaffney, C. Gunnar Blomqvist

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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).

Original languageEnglish (US)
Pages (from-to)7-18
Number of pages12
JournalJournal of Applied Physiology
Volume81
Issue number1
Publication statusPublished - Jul 1996

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Keywords

  • orthostatic hypotension
  • syncope

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Buckey, J. C., Lane, L. D., Levine, B. D., Watenpaugh, D. E., Wright, S. J., Moore, W. E., ... Blomqvist, C. G. (1996). Orthostatic intolerance after spaceflight. Journal of Applied Physiology, 81(1), 7-18.