VENTILATORY DYNAMICS UNDER HYPERBARIC STATES
NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL
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Eleven U. S. Navy divers performed comparative dynamic pulmonary function tests under conditions of increasing density of the respiratory media. Variations in density and viscosity were produced by having the subjects breath air and heliumoxygen mixes in alternate studies while being subjected successively to 1 through 15 atmospheres absolute pressure. Substitution of 95 helium-5 oxygen at 15 atm. abs. produced significantly less variation from normal in all parameters measured. Mean figures were 76.8 of predicted MBC, 70. 9 first second TVC, and an MEF of 281 LPM. The increased work of breathing accompanying increased density of the respiratory media probably accounts for the relative decrease in RMV previously observed in underwater swimmers. Helium- oxygen mixtures provide a more ideal respiratory media than nitrogen-oxygen mixtures for marked hyperbaric conditions, especially under circumstances requiring high flow rates and large respiratory minute volumes.
- Anatomy and Physiology
- Life Support Systems