title: Prolonged whole-body cold water immersion: fluid and ion shifts.
abstract: To characterize fluid and ion shifts during prolonged whole-body immersion, 16 divers wearing dry suits completed four whole-body immersions in 5 degrees C water during each of two 5-day air saturation dives at 6.1 msw. One immersion was conducted at 1000 (AM) and one at 2200 (PM) so that diurnal variations could be evaluated. Fifty-four hours separated the immersions, which lasted up to 6 h; 9 days separated each air saturation dive. Blood was collected before and after immersion; urine was collected for 12 h before, during, and after immersion for a total of 24 h. Plasma volume decreased significantly and to the same extent (approximately 17%) during both AM and PM immersions. Urine flow increased by 236.1 +/- 38.7 and 296.3 +/- 52.0%, urinary excretion of Na increased by 290.4 +/- 89.0 and 329.5 +/- 77.0%, K by 245.0 +/- 73.4 and 215.5 +/- 44.6%, Ca by 211.0 +/- 31.4 and 241.1 +/- 50.4%, Mg by 201.4 +/- 45.9 and 165.3 +/- 287%, and Zn by 427.8 +/- 93.7 and 301.9 +/- 75.4% during AM and PM immersions, respectively, compared with preimmersion. Urine flow and K excretion were significantly higher during the AM than PM. In summary, when subjects are immersed in cold water for prolonged periods, combined with a slow rate of body cooling afforded by thermal protection and enforced intermittent exercise, there is diuresis, decreased plasma volume, and increased excretions of Na, K, Ca, Mg, and Zn.
authors.affiliation: Department of Military Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
authors.forename: P A
authors.initials: PA
authors.lastname: Deuster
authors.forename: D J
authors.initials: DJ
authors.lastname: Smith
authors.forename: B L
authors.initials: BL
authors.lastname: Smoak
authors.forename: L C
authors.initials: LC
authors.lastname: Montgomery
authors.forename: A
authors.initials: A
authors.lastname: Singh
authors.forename: T J
authors.initials: TJ
authors.lastname: Doubt
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis; D001810:Blood Volume; D001826:Body Fluids / Q000378:metabolism*; D002940:Circadian Rhythm; D003080:Cold Temperature; D006801:Humans; D007101:Immersion; D007477:Ions; D008297:Male; D013997:Time Factors; D014556:Urine / Q000032:analysis
chemical_list: D007477:Ions