Cooling Effect of Fluid Replacement During

Transcription

1 Cooling Effect of Fluid Replacement During Heavy Sweating Seiji YAMADA*, Chikanobu MATSUBARA*, Hiroshi NOSE*, Kenju MIKI*, Toshiyuki ITOH*, Yoshiteru SEO*, Kazufumi HIRAKAWA* and Taketoshi MORIMOTO* * Department of Physiology, Kyoto Prefectural University of Medicine (Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602 JAPAN) Nine male subjects were exposed to combined stress of heat (36 Ž, 60% R. H.) and exercise by ergometer (70% o2 max) for 2 hours. Rectal temperature, mean skin temperature and heat balance were measured, and hematocrit value, concentration of plasma protein, ph, Pco2, plasma osmolality and concentration of ions in plasma were determined together with sweat and urine volume and their ionic compositions. These observations were repeated four times on each subject: without any fluid replacement (dehydration exp.), with ingestion of cold distilled water (250 ml) every 30 min (cold water exp.), with ingestion of a cold glucose-electolyte solution (250 ml) every 30 min (cold G-E exp.) and with a hot glucose-electrolyte solution (250 ml) every 30 min (hot G-E exp.). The results obtained are as follows: 1) A significant difference was found on rectal temperature between the dehydration exp. and the cold fluid replacement exp. The difference was due to the effect of central cooling of ingested fluid.2) Plasma sodium and chloride concentrations were increased in the dehydration exp., while they were decreased in the other exps. Loss of NaCI from plasma was equal among 4 exps., but loss of water from plasma was about 3 times more in dehydration exp, than that in the other exps.3) Determination of Pco2 and ph of venous blood showed a tendency of tachypnea in the dehydration exp, and the hot G-E exp., while the degree was less in the cold fluid replacements. k Jpn. J. Biometeor. 19(1): 45-51, 1982 l

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3 FIG. 1 Changes in rectal temperature, mean skin temperature and mean body temperature during 2 hours of combined stress of heat and exercise by ergometer. Values are shown as the difference from the control values. Mean values of dehydration experiment ( œ), experiments with cold distilled water (cold water exp., ), with a cold glucose-electrolyte solution (cold G-E exp., ) and with a hot glucose-electrolyte solution (hot G-E exp., ) are shown. Hatched bars represent exercise by ergometer. FIG. 2 Heat balance during 2 hours of combined stress of heat and exercise. Values are shown as the difference from dehydration experiment. Columns from left to right represent dehydration experiment, cold G-E experiment, hot G-E experiment and cold water experiment. **or***represents significant difference from dehydration experiment at the level of p ƒ0.01 or p ƒ

4 the control values. Means and SD's under the 4 experimental conditions are shown. FiG. 3 Changes in hematocrit, plasma protein concentration, carbon dioxide pressure and ph of venous blood during 2 hours of combined stress of heat and exercise. Values are shown as the difference from Keys for columns are same as in FIG. 2. FIG. 4 Changes in serum concentration of sodium, potassium and chloride, and serum osmolality during 2 hours of combined stress of heat and exercise. Values are shown as the difference from the control values. Columns used are same as FIG. 2. *represents significant differencnce between two experiments at the level of p ƒ0.05.

5 FIG. 5 Balance of ions of sodium, potassium and chloride, osmolality and water during 2 hours of combined stress of heat and exercise. Means and SD's under the 4 experimental conditions are shown. Columns used are same as FIG. 2. In each column, bottom column represents the amount of loss from sweat and top column represents that from urine. Hatched columns represent the amount of replacement of each component.

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7 2) Cade, R., Spooner, G., Schlein, E., Pickering, M., and Dean, R.: Effect of fluid, electrolyte, and glucose replacement during exercise on performance, body temperature, rate of sweat loss, and compositional changes of extracellular fluid. J. Sports Med., 12, , ) Hardy, J. D. and DuBois, E. F.: The Technic of Measuring Radiation and Convection. J. Nutr., 15, , ) Londeree, B. R., Updyke, W. F. and Burt, J. J.: Water Replacement Schedules in Heat Stress. Res. Quart., 40, , ) Snellen, J. W. and Mitchell, D.: Calorimetric analysis of the effect of drinking saline solution on whole-body sweating. II. response to different volumes. Pflugr. Arch 331, , ) Myhre, L. G. and Robinson, S.: Fluid shift during thermal stress with and without fluid replacement. J. Appl. Physiol., 42, , 1977.