Trimix at Depths Below 1000 FSW.
Abstract
The dives reported here were planned to investigate the same partial pressure of nitrogen (3.5 ATA) at 396 m (1300 fsw) and 488 m (1600 fsw), but at 464 m (1521 fsw), fatigue, dizziness, and nausea were such that compression was terminated. It had been hoped that a lower nitrogen percentage plus a slower compression rate would reduce any possible respiratory problems as well as the HPNS. At 6 percent nitrogen, however, with a compression rate to 400 m (1312 fsw) of 2 h, HPNS occurred along with fatigue, confusion, dizziness, and slight nausea. Performance tests indicated a -55 percent mean decrement for mathematics, improving to -42 percent over 2 h and the ball bearing test showed improvement from -25 to -10 percent. The EEG showed increased theta activity; intentional tremor increased by 80 percent from atmospheric controls. At 5 percent nitrogen, compression was made toward 1600 fsw at a slower rate, with 150 min to 1312 fsw and a 20-min stage there. At 1312 fsw the divers felt good with much less HPNS. The mathematics test indicated a decrement of -31 percent; the ball bearing test indicated -42 percent. On compression to 1521 fsw the divers became fatigued, sleepy, and nauseated; theta activity increased; and intentional tremor rose 160 percent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1976
- Accession Number
- ADA046846
Entities
People
- A. J. Bachrach
- D. Burgess
- M. J. Ackerman
- P. B. Bennett
Organizations
- Naval Medical Research Center