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Cardiovascular Responses to Repetitive Exposure to Hyper‐ and Hypogravity States Produced by Parabolic Flight
Author(s) -
Mukai Chiaki N.,
Lathers Claire M.,
Charles John B.,
Bennett Barbara S.
Publication year - 1994
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1994.tb04989.x
Subject(s) - parabola , hypergravity , supine position , cardiac index , cardiac output , weightlessness , medicine , stroke volume , cardiology , impedance cardiography , preload , sitting , hemodynamics , heart rate , mathematics , anesthesia , physics , blood pressure , geometry , pathology , astronomy
Physiologic changes to repetitive hyper‐ and hypogravity stresses occurring during eight to ten parabolas on NASA's KC‐135 aircraft were studied. Hemodynamic responses in 11 subjects in 4 different postures (supine, standing, sitting, and semisupine Space Shuttle launch position) were determined using noninvasive impedance cardiography. Five seconds of heart rate, cardiac index, thoracic fluid index, stroke index, ejection velocity index, and ventricular ejection time data were averaged during four different gravity (g) states: 1.3g (before parabola onset); 1.9g (parabola entry); 0g (parabola peak); and 1.7g (parabola exit) for each subject. The standing position was associated with the largest changes in the cardiovascular response to hypo‐ and hypergravity. The thoracic fluid index did not indicate a headward redistribution during transition from a simulated launch position to weightlessness. Analysis of the eight to ten parabolas revealed that, in general values obtained at 1.8g differed from 1.6g, 0g differed from 1.6 and 1.3g, and 1.6g differed from 1.3g. The factors of gravity, thoracic fluid index, and cardiac index exhibited significant differences that were most likely to occur between parabola 1 versus parabolas 6, 7, and 8, and parabola 2 versus parabolas 4 through 8. Only the parameter of thoracic fluid index exhibited significance for parabolas 3 versus parabolas 6 and 7.