Dyspnea in Divers at 49.5 ATA: Mechanical not Chemical in Origin.

摘要

Technical advances in the past four decades have made it possible to study man's performance at pressures more than 60 times normal (equivalent to 2000 ft seawater (fsw) using helium-oxygen breathing mixtures. Such studies are generally done in hyperbaric chambers ashore, but open-sea dives deeper than 1100 fsw have recently been made. This sort of diving has commercial, scientific, and military uses, but the safe depth limits for human exposure are not yet known, nor are the factors which may set such limits. One limiting factor may be the ability of the respiratory system to support metabolic processes at great depths. Even with helium-oxygen breathing mixtures, gas density exceeds a value seven times normal (air, 1 ATA) at 1600 fsw. We have considered the question of respiratory function at great depths, and this study reports the results of measurements made in a hyperbaric chamber complex at a maximum pressure near 50 ATA. This pressure was selected because we wished to study man's ability to work underwater, and therefore needed to avoid the more serious neurological disturbances which occur at greater pressures. (Author)