Body thermal drain under hyperbaric dry heliox environment with undersea excursion dive.

A series of undersea experiments were undertaken at the Japan Marine Science and Technology Center since 1972 in order to investigate thermal drain due to higher heat conductivity of helium which is essential as a breathing medium in deep-sea diving substituting for nitrogen in the air. While the less narcotic effect and the low density of the gas is adequate for maintaining better respiratory functions of divers, distortion of the diver's voice due to low density and thermal drain should be overcome. Measuring body heat loss in a hyperbaric dry environment, wet pot thermistors and heat flux transducers were applied at four to seven points on the body surface before, during, and after hyperbaric exposure to 11 ATA. As a result it was acknowledged that heat loss from the body surface, in hyperbaric heliox environment, was greater than that at the 1 ATA condition. Further, additional heat loss during immersion proved significant. The other modifying factors revealed were ambient water temperature, kinds of diving suits or underwear, and others.