Thermal Equilibrium Studies on Men Breathing Helium-Oxygen Mixtures.

Abstract : Studies which were conducted on divers before and after their Sea Lab exposures indicated that as a consequence of this exposure, a reduction in their maximal work capacity occurred and that the cost of submaximal work was greater. The men showed some evidences of acclimatization to cold. Additional studies were made to determine the relative contributions of core and surface receptors to the maintenance of thermal balance. It was shown that the thermal regulatory system was directly responsive to the thermal input from skin and that this has direct application to the problems faced by divers working in cold water. Studies of subjects working in helium-oxygen atmospheres (1 AA) at different ambient temperatures indicated a marked subjective impression of greater cooling which was not borne out by objective data. Progress was made towards developing a system to measure body temperatures in working divers. Considerable difficulty was experienced with tape deck systems, attempting to obtain eight hours continuous data on a single small spool, because battery life and power were markedly influenced by low temperatures. A new approach of considerable promise is under development which would eliminate most of the problems present in the initial systems. (Author)