Orthostatic intolerance and motion sickness after parabolic flight

Todd T. Schlegel, Troy E. Brown, Scott J. Wood, Edgar W. Benavides, Roberta L. Bondar, Flo Stein, Peyman Moradshahi, Deborah L. Harm, Janice M. Fritsch-Yelle, Phillip A. Low
2001 Journal of applied physiology  
Orthostatic intolerance and motion sickness after parabolic flight. J Appl Physiol 90: [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] 2001.-Because it is not clear that the induction of orthostatic intolerance in returning astronauts always requires prolonged exposure to microgravity, we investigated orthostatic tolerance and autonomic cardiovascular function in 16 healthy subjects before and after the brief micro-and hypergravity of parabolic flight. Concomitantly, we
more » ... itantly, we investigated the effect of parabolic flight-induced vomiting on orthostatic tolerance, R-wave-R-wave interval and arterial pressure power spectra, and carotid-cardiac baroreflex and Valsalva responses. After parabolic flight 1) 8 of 16 subjects could not tolerate 30 min of upright tilt (compared to 2 of 16 before flight); 2) 6 of 16 subjects vomited; 3) new intolerance to upright tilt was associated with exaggerated falls in total peripheral resistance, whereas vomiting was associated with increased R-wave-R-wave interval variability and carotidcardiac baroreflex responsiveness; and 4) the proximate mode of new orthostatic failure differed in subjects who did and did not vomit, with vomiters experiencing comparatively isolated upright hypocapnia and cerebral vasoconstriction and nonvomiters experiencing signs and symptoms reminiscent of the clinical postural tachycardia syndrome. Results suggest, first, that syndromes of orthostatic intolerance resembling those developing after space flight can develop after a brief (i.e., 2-h) parabolic flight and, second, that recent vomiting can influence the results of tests of autonomic cardiovascular function commonly utilized in returning astronauts. postural tachycardia syndrome; vomiting; microgravity; hypergravity; autonomic; space flight ORTHOSTATIC INTOLERANCE is common in returning astronauts (6, 13). However, it is not clear that prolonged exposure to microgravity is always required to induce this problem. For example, some astronauts with nor-
doi:10.1152/jappl.2001.90.1.67 pmid:11133895 fatcat:itbgnq4fl5b4fpsxifo3buliuq