Document Detail


Decompression sickness latency as a function of altitude to 25,000 feet.
MedLine Citation:
PMID:  12433227     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
INTRODUCTION: Current Air Force Instructions (AFIs) allow flight of unrestricted duration in unpressurized aircraft up to 25,000 ft. Supplemental oxygen is required to prevent hypoxia, but decompression sickness (DCS) is not adequately considered in current oxygen use guidelines. Recent information from the Air Force Research Laboratory (AFRL) DCS database, combined with a projected increase in exposure to these altitudes under proposed USAF missions, suggests that DCS may be operationally significant in certain circumstances. METHODS: The AFRL Altitude Decompression Sickness Risk Assessment Computer (ADRAC) model was used to develop a family of curves representing DCS latency (time to symptom onset) as a function of altitude for the case of zero preoxygenation and mild exercise. The DCS database was then searched for serious DCS cases among subjects under the same conditions (n = 175). An upper limit for DCS incidence that avoided serious DCS symptoms was selected and exposure time limits were determined. Preoxygenation requirements necessary to remain below the selected DCS incidence limit were also evaluated using ADRAC and provide an alternative to time limits. RESULTS AND DISCUSSION: The 20% DCS curve met the above criteria. Based on this, continued unlimited exposure time is recommended for 21,000 ft and below. The 20% DCS risk curve for zero-prebreathe exposures to 25,000 ft, 24,000 ft, 23,000 ft, and 22,000 ft are reached at 45 min, 70 min, 120 min, and 200 min, respectively. Consistent with existing AFIs, flying unpressurized above 25,000 ft is not recommended. These times should be reduced for crewmembers engaged in heavy physical activity at altitude. CONCLUSIONS: This article proposes time limits for unpressurized flight above 21,000 ft to reduce DCS risk.
Authors:
Terry L Haske; Andrew A Pilmanis
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  73     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2002 Nov 
Date Detail:
Created Date:  2002-11-15     Completed Date:  2003-02-21     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1059-62     Citation Subset:  IM; S    
Affiliation:
Graduate Education Division, US Air Force School of Aerospace Medicine, Brooks AFB, TX 78235-5104, USA.
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MeSH Terms
Descriptor/Qualifier:
Aerospace Medicine / standards
Aircraft / standards
Altitude*
Atmospheric Pressure*
Databases, Factual
Decompression Sickness / epidemiology,  prevention & control*
Exercise / physiology
Humans
Incidence
Military Personnel
Oxygen Inhalation Therapy
Practice Guidelines as Topic
Risk Assessment
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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