Preoxygenation Time versus Decompression Sickness Incidence

摘要

The cabin altitude experienced by U-2 pilots during high altitude reconnaissance missions is approximately 30,000 feet. Increasing the duration of preoxygenation (i.e., breathing 100% oxygen prior to decompression to reduce the incidence of decompression sickness (DCS)), increases denitrogenation, but is impractical due to mission time constraints and crew duty limitations. Use of exercise-enhanced preoxygenation instead of increasing the duration of preoxygenation to provide better protection from DCS has been successfully demonstrated in the laboratory. This report describes the first operational use of this new procedure. A U-2 pilot, who had previously reported serious DCS symptoms resulting in mission aborts during two of his first twenty-five high- altitude flights, volunteered to operationally try the exercise-enhanced preoxygenation procedure. His next 28 U-2 high-altitude flights incorporated moderate aerobic upper and lower body exercise at a controlled rate during the first 10 minutes of a 90-minute preoxygenation. The total preoxygenation time was of the same duration as accomplished prior to his last aborted mission. The pilot reported no DCS symptoms during the subsequent 28 high-altitude flights. An operational trial of exercise-enhanced preoxygenation has been shown to be feasible under operational constraints and, to date, has been successful.