Altitude Decompression Sickness at 7,620 m Following Prebreathe Enhanced With Exercise Periods
Journal article, Jan 2001-Aug 2003
WYLE LABS LIFE SCIENCES AND SERVICES INC SAN ANTONIO TX
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Over 80 altitude decompression sickness DCS was reported during a 4-h exposure with mild exercise to 7620 m 25,000 ft without prebreathe. Prebreathe for more than 1 h would be necessary to reduce the DOS risk below 40. Use of a single period of exercise to enhance prebreathe effectiveness has been successfully tested and used during some U-2 operations. The current tests used multiple exercise sessions to enhance prebreathe MEEP as a means of improving denitrogenation efficiency. Methods. Two MEEP profiles, 30 or 60 min, preceded 4-h exposures to 7620 m with mild, upper-body exercise while breathing 100 oxygen. Resting prebreathe controls were from published studies at the same laboratory. Both MEEP profiles involved 10 min of strenuous dual-cycle ergometry 75 of maximal oxygen uptake at the beginning of prebreathe. After a I 5-min rest period during the 60-min prebreathe an additional 5 min of strenuous ergometry was performed. Mild exercise was performed during 15 of the last 20 min of both prebreathe profiles. Results. The 60-min MEEP resulted in 25 DOS and the 30-min MEEP 40 DOS N.S.. The 25 incidence of DOS following the 60-min MEEP profile was significantly less than the 63 DOS following an equal-time, resting prebreathe control. Following the 30-min MEEP, DOS incidence was not greater than the incidence following a 60-min, resting prebreathe control. There was a lower incidence of venous gas emboli during the MEEP exposures than during resting control exposures. Conclusion. Denitrogenation with multiple periods of exercise provides a shorter alternative to resting prebreathe for reducing DOS risk during exposure to 7620 m.
- Medicine and Medical Research
- Stress Physiology