PULMONARY AND CIRCULATORY ADJUSTMENT DETERMINING THE LIMITS OF DEPTHS IN BREATHHOLD DIVING
Abstract
Data on pulmonary gas exchange were collected in breathhold dives to 90 feet at the Escape Training Tank, Naval Submarine Base, Groton, Conn. and in open sea breathhold dives, off Ft. Lauderdale, to a depth of 217.5 feet on diver R. Croft. Thoracic blood volume displacements were measured at depths of 25, 50, 90, and 130 feet, using the impedance plethysmograph. The open sea dives were carried out with an average speed of descent of 3.95 feet per second using a 65-pound cable break and an average rate of ascent of 3.50 feet per second pulling up the line. End dive alveolar oxygen tensions did not fall below 40 mm Hg, while alveolar CO2 tension did not rise above 40 mm Hg except in one case. These findings indicate that neither hypoxia nor hypercapnia determined the depth limits under those conditions. At depths of 90 and 130 feet blood was forced into the thorax, amounting to 1047 and 850 ml respectively. This is the first direct evidence of intrathoracic blood pooling in breathhold diving at greater depths. It explains the extension of Croft's 197-foot depth threshold calculated from his total lung volume/residual volume ratio to depths of 217.5 feet actually reached in his world record dive.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 05, 1968
- Accession Number
- AD0675815
Entities
People
- Charles R. Carey
- James H. Dougherty Jr.
- Karl E. Schaefer
- Robert D. Allison
- Roger C. Walker
Organizations
- Naval Submarine Medical Research Laboratory