Trimix at Depths Below 1000 FSW.
Medical research progress rept. no. 6,
NAVAL MEDICAL RESEARCH INST BETHESDA MD
Pagination or Media Count:
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.
- Stress Physiology