Effect of hydration on nitrogen washout in human subjects

Five subjects were tested to assess the influence of drinking hypotonic water (distilled water) on whole body tissue nitrogen washout. During the test, the subjects breathed aviators' oxygen for three hours. Each subject performed two baseline nitrogen washouts in a two-week period. The third washout, in the third week, was done under a transient hydrated condition. This was accomplished by having the subjects drink 1.5 liters of hypotonic water 30 minutes before the washout. Five-minute plots of tissue nitrogen removal from the three separate washouts were analyzed to ascertain if the hydration technique had any effect. Our results clearly indicate that the hydration technique did not alter the tissue nitrogen washout characteristics to any degree over three hours. An increase in tissue nitrogen washout under a transient hydrated condition using hypotonic fluid was not demonstrated to be the mechanism responsible for the reported benefit of this technique in preventing Type I altitude decompression pain in man.