CARBON DIOXIDE EFFECTS UNDER CONDITIONS OF RAISED ENVIRONMENTAL PRESSURE by

Exposure to increased pressure, such as that encountered under water, affects the mechanics of respiration and in particular, the behavior of the respiratory gases. Carbon dioxide plays a major role in the physiology of the high-pressure environment, since the increased breathing resistance easily leads to carbon dioxide retention. The latter has been observed frequently in scuba and helmet diving. Pulmonary gas exchange in breathhold diving is influenced by the compression and decompression events resulting in a reversed carbon dioxide gradient during descent. The alveolar carbon dioxide level can be controlled during the ascent from depth by controlling the speed of ascent, a fact which is of significance to both breathhold diving and the buoyant ascents of submarine escape. Investigations of pulmonary gas exchange in rest and exercise during exposure to high pressure while breathing helium-oxygen gas mixtures have demonstrated the existence of respiratory limitations and associated COg retention when divers are performing heavy, exhaustive work. In shallow habitat air diving using combinations of air and normoxic nitrogen-oxygen breathing mixtures, evidence for the development of slight respiratory acidosis and CO2 retention has been obtained. Clip and Mail Form for Change of Address To: Commanding Officer, Naval Submarine Medical Research Laboratory, Attn: Code 03B Subj: Change of Address 1, i/We wish to continue to receive NavSubMedRschLab Reports, however, the following change of address should be noted: