SIMULATED MULTIDAY UNDERWATER HABITATION IN HYPERBARIC HELIUM-OXYGEN ENVIRONMENT

During the last decade underwater habitations have been planned and carried out in several countries. In Japan, an underwater habitation of 60 meters by 4 men for 7 days (named "Seatopia" project) was carried out by the Japan Marine Science and Technology Center (JAMSTF.C) in 1973. Before the actual project, safety check of the equipment and selection of candidates were required from the viewpoint of medical sciences. After that, 7 subjects, candidates for "aquanauts" lived in a hyperbaric chamber of 7 atmosphere absolute pressure air and helium simulating an underwater habitat of 60 m depth, for 7 clays (in total 15 days including 3 clays of control before compression, 3 clays of decompression, 2 clays after decompression). Physiological functions of all the subjects were examined for more than 2 weeks. Effects of high pre3sure and thermal conductivity on cardiorespiratory system, renal function and metabolism were evaluated with the findings of 1) decreased heart rate and forced expiratory volume; 2) increased urine volume; 3) decreased rectal and skin temperature with increased heat production and 4) the more trained the diver, the lower the skin temperature and the lower the heat production