Hana kai ii: a 17-day dry saturation dive at 18.6 ATA. II. Energy balance

Since previous saturation dives have caused loss of body weight despite apparently adequate-to-high food intake, a complete study of energy balance was undertaken during the saturation dive Hana Kai II. Over a 30-day period in the hyperbaric chamber (3 days of predive control, 1 day of compression, 16 days at 18.6 ATA, 7 days of decompression, and 3 days of postdive control), all food, urine, and feces for five men were analyzed by bomb calorimetry; 24-h energy expenditure (M) was measured from continuous VO2, VCO2, and urine N. Body weight was taken daily; body composition was assessed from density, total body water, and skinfold thickness. Food intake was high throughout the 30 days (about 3500 kcal/day) while fecal and urinary losses were a normal 6-8% of intake. Energy expenditure was increased a little by the hyperbaric condition, but averaged only 2431 kcal/day for the 30 days and yet there was an average loss of adipose tissue of 0.8 kg for each man for the entire period. Nitrogen balance was positive. There was no evidence of heat gain or loss. The energy balance, total fuel compared with energy expenditure, required an additional 919 kcal/man-day for 30 days, an unidentified term which is not measured by conventional techniques.