Publications by authors named "Asbjørn Aakvaag"

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Time and temperature effects on body fluid loss during dives with the open hot-water suit.

Aviat Space Environ Med 2005 Jul;76(7):655-60

Norwegian Underwater Intervention a.s, Bergen, Norway.

Background: Bodyweight (BW) losses up to 5 kg have been observed during diving with the open hot-water suit (HWS). The objective of these dives was to study the hormonal, hematological, and renal effects of dehydration during shallow HWS diving.

Methods: In series 1, four divers dove for 3.5 h each day for 7 d. In series 2, 12 divers dove to 6-8 msw for 1, 2, and 4 h. Blood and urine samples, BW measurements, oral temperature, and thermal stress indices were collected.

Results: Average deltaBW (+/- SD) for the 28 dives in series 1 was 1.5 +/- 0.8 kg, and the largest BW reductions were 3.2 and 3.0 kg, corresponding to 3.7 and 4.7% of BW. Changes in thermal stress, hemoglobin, hematocrit, aldosterone, and electrolyte excretion correlated with BW reduction. In series 2, average BW reductions were 0.46 +/- 0.27, 0.96 +/- 0.38, and 1.55 +/- 0.59 kg during 1-, 2-, and 4-h dives. BW reduction correlated significantly with thermal stress (p < 0.01). Aldosterone increased after 1 and 2 h and plasma renin activity was unchanged. Atrial natriuretic peptide increased in all dives (p < 0.01) and arginine vasopressin increased in the 4-h dives (p < 0.05). The 7.2% decrease in plasma volume, the increases in hemoglobin, hematocrit and serum proteins, and an unchanged plasma osmolality indicate an isotonic dehydration after the 4-h dives.

Conclusions: BW loss during HWS diving is mainly caused by sweating. Dives of 4 h produce an isotonic dehydration and a break for fluid intake is, therefore, recommended.
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July 2005