Document Detail


The effect of staged decompression while breathing 100% oxygen on altitude decompression sickness.
MedLine Citation:
PMID:  10902932     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
INTRODUCTION: Space Shuttle extravehicular activity (EVA) requires decompression from sea level pressure (14.7 psia) to a 4.3 psia (30,300 ft) pressure suit. The transition currently involves altering the shuttle atmosphere to allow shirt-sleeve denitrogenation to occur during a 12 to 36-h staged decompression (SD) at 10.2 psia (9,800 ft) with an oxygen-enriched breathing gas (26.5% oxygen, 73.5% nitrogen). The denitrogenation provides protection from decompression sickness (DCS) during EVA in a 4.3 psia pressure suit. Our goal was to determine the highest altitude at which SD while breathing 100% oxygen (SD100) could provide effective protection from development of DCS symptoms after further decompression to 29,500 ft (4.5 psia). METHODS: There were 30 male subjects exposed to at least 6 of 11 conditions in random order on successive months to 29,500 ft for 4 h while performing mild exercise and being monitored for venous gas emboli (VGE) with an echo-imaging system. The subjects received 15 min of ground-level (GL) preoxygenation and an additional 60 or 120 min of SD100 at one of four altitudes between 8,000 ft (10.9 psia) and 18,000 ft (7.3 psia). Control exposures followed a 75- or 135-min ground-level preoxygenation. RESULTS: During SD100, one case of DCS occurred at 18,000 ft, but not at lower staging altitudes. Higher levels of VGE were observed during SD100 at 18,000 ft than during SD100 at any lower altitude. CONCLUSION: Staged decompression at 16,000 ft and below results in decompression risk during subsequent decompression to 29,500 ft similar to that following equivalent periods of ground-level preoxygenation.
Authors:
J T Webb; A A Pilmanis; N Kannan; R M Olson
Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  71     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2000 Jul 
Date Detail:
Created Date:  2000-11-16     Completed Date:  2000-11-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  692-8     Citation Subset:  IM; S    
Affiliation:
Air Force Research Laboratory in San Antonio, TX, USA. james.webb@brooks.af.mil
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MeSH Terms
Descriptor/Qualifier:
Altitude Sickness / etiology,  physiopathology,  therapy*
Decompression / methods*
Decompression Sickness / etiology,  physiopathology,  therapy*
Extravehicular Activity / adverse effects
Humans
Male
Oxygen Inhalation Therapy / methods*
Risk Factors
Time Factors

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


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