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Effect of hypovolemia, infusion, and oral rehydration on gradual onset +Gz acceleration toleranceThe purpose of this study was to determine the effect of blood withdrawal, blood infusion, and oral fluid intake on +Gz tolerance at an acceleration rate of 0.5 G/min. Six healthy men aged 21-27 yr were centrifuged after the withdrawal of 400 ml of blood (hypovolemia) from each man; they were centrifuged again following blood infusion (Phase I). Three weeks later the men were accelerated after similar hypovolemia and again after consuming 800 ml of an isotonic NaCl drink (Phase II). Phase I hypovolemia resulted in a reduction in tolerance in all subjects from a mean control level of 6.42 + or - 0.35 min to 5.45 + or - 0.17 min (-15.1%, p less than 0.05). Both infusion and drinking returned tolerances to control levels. During acceleration there were significant (p less than 0.05) increases in plasma vasopressin levels to 35 pg/ml; these were not influenced appreciably by infusion or drinking. In all acceleration runs there was an obligatory shift (loss) of plasma volume and electrolytes, especially potassium, regardless of the experimental treatments. Oral rehydration is shown to be as effective as blood replacement in restoring +Gz acceleration tolerance decrements due to hypovolemia.
Document ID
19770028036
Document Type
Conference Paper
Authors
Greenleaf, J. E. (NASA Ames Research Center Moffett Field, CA, United States)
Brock, P. J. (NASA Ames Research Center Moffett Field, CA, United States)
Haines, R. F. (NASA Ames Research Center Moffett Field, CA, United States)
Rositano, S. A. (NASA Ames Research Center Moffett Field, CA, United States)
Montgomery, L. D. (NASA Ames Research Center Moffett Field, CA, United States)
Keil, L. C. (NASA Ames Research Center Moffett Field, Calif., United States)
Date Acquired
August 8, 2013
Publication Date
October 1, 1976
Subject Category
AEROSPACE MEDICINE
Report/Patent Number
IAF PAPER 76-039
Meeting Information
International Astronautical Congress(Anaheim, CA)
Funding Number(s)
CONTRACT_GRANT: NCA2-OR180-506
Distribution Limits
Public
Copyright
Other