Body fluid shifts during space flight require special attention because they are associated with pathophysiologic changes that may interfere with human performance. Several previous studies have shown that body fluid shifts occurring during space flight can be adequately simulated on the ground by means of head-down tilt (HDT) experiments. The use of invasive procedures for data gathering poses, however, important limitations to research in this area. Exploring the use of non-invasive methods is, therefore, warranted. One of these methods has its basis on electrical impedance measurements. The purpose of this paper is to report the authors' experience with this method. The experimental studies were conducted on ten healthy men. Measurements were taken standing and immediately after assuming a 6 deg HDT for a period of 6 hours. Measurements at two electric frequencies (Z 1.5 kHz and Z 150 kHz) were taken every 15 min and plotted, together with the ratio Z 1.5 Z 150, versus time. The curves thus obtained showed changes in these three variables which exhibited a fixed pattern. This pattern is consistent with the interpretation that HDT produces a cephalad shift of body fluids and a relative decrease in extracellular fluid volume. Should impedance measurements be validated by independent experiments or more direct measurement techniques they would prove to be particularly suitable for non-invasive dynamic studies of body fluid shifts.
Electric impedance measurements of body fluid shifts in simulated microgravity
Elektrische Impedanzmessungen von Körperflüssigkeitsverschiebungen während simulierter Mikrogravitation
Automedica ; 12 , 3 ; 211-219
1990
9 Seiten, 2 Bilder, 3 Tabellen, 16 Quellen
Article (Journal)
English
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