Accession Number:

ADA426912

Title:

An Abrupt Zero-Preoxygenation Altitude Threshold for Decompression Sickness Symptoms

Descriptive Note:

Journal article, Nov 1990-Jan 1996

Corporate Author:

WYLE LABS LIFE SCIENCES AND SERVICES INC SAN ANTONIO TX

Report Date:

1998-04-01

Pagination or Media Count:

7.0

Abstract:

The altitude threshold for decompression sickness DCS symptoms has been variously described as being 18,000 ft 5,487 m to above 25,000 ft 7,620 m. Safety and efficiency of aerospace operations require more precise determination of the DCS threshold. One hundred fifteen male human-subjects were exposed to simulated altitude 11 at 11,500 ft 10 at 15,000 ft 8 at 16,500 ft 10 at 18,100 ft 10 at 19,800 ft 20 at 21,200 ft 20 at 22,500 ft 10 at 23,800 ft, and 16 at 25,000 ft for up to 4 h. All breathed 100 oxygen beginning with ascent. Subjects were monitored for precordial venous gas emboli VGE and DOS symptoms. Probit curves representing altitude versus incidence of DCS symptoms and VGE allowed estimation of respective risk. VGE were first observed at 15,000 ft with increasing incidence at higher altitudes over 50 at 21,200 ft and at least 70 at 22,500 ft and above. DCS symptoms were first reported at 21,200 ft with an incidence of 5. At 22,500 ft, the DOS incidence climbed to 60. The 5 threshold for zero-preoxygenation altitude DCS symptoms is at 21,000 ft and an abrupt increase in DCS symptom incidence with increased altitude.

Subject Categories:

  • Stress Physiology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE