Document Detail


The effect of simulated weightlessness on hypobaric decompression sickness.
MedLine Citation:
PMID:  12182217     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: A discrepancy exists between the incidence of ground-based decompression sickness (DCS) during simulated extravehicular activity (EVA) at hypobaric space suit pressure (20-40%) and crewmember reports during actual EVA (zero reports). This could be due to the effect of gravity during ground-based DCS studies. HYPOTHESIS: At EVA suit pressures of 29.6 kPa (4.3 psia), there is no difference in the incidence of hypobaric DCS between a control group and group exposed to simulated weightlessness (supine body position). METHODS: Male subjects were exposed to a hypobaric pressure of 29.6 kPa (4.3 psi) for up to 4 h. The control group (n = 26) pre-oxygenated for 60 min (first 10 min exercising) before hypobaric exposure and walking around in the altitude chamber. The test group (n = 39) remained supine for a 3 h prior to and during the 60-min pre-oxygenation (also including exercise) and at hypobaric pressure. DCS symptoms and venous gas emboli (VGE) at hypobaric pressure were registered. RESULTS: DCS occurred in 42% in the control and in 44% in simulated weightlessness group (n.s.). The mean time for DCS to develop was 112 min (SD +/- 61) and 123 min (+/- 67), respectively. VGE occurred in 81% of the control group subjects and in 51% of the simulated weightlessness subjects (p = 0.02), while severe VGE occurred in 58% and 33%, respectively (p = 0.08). VGE started after 113 min (+/- 43) in the control and after 76 min (+/- 64) in the simulated weightlessness group. CONCLUSIONS: No difference in incidence of DCS was shown between control and simulated weightlessness conditions. VGE occurred more frequently during the control condition with bubble-releasing arm and leg movements.
Authors:
Ulf I Balldin; Andrew A Pilmanis; James T Webb
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  73     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2002 Aug 
Date Detail:
Created Date:  2002-08-16     Completed Date:  2003-01-10     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:  773-8     Citation Subset:  IM; S    
Affiliation:
Air Force Research Laboratory, Biodynamics and Protection Division, Brooks Air Force Base, TX 78235-5104, USA. ulf.balldin@brooks.af.mil
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Aerospace Medicine
Arm / physiology
Decompression Sickness / etiology*
Exercise Test
Extravehicular Activity / adverse effects
Humans
Incidence
Leg / physiology
Male
Middle Aged
Movement / physiology
Oxygen Inhalation Therapy
Prospective Studies
Supine Position
Time Factors
Weight-Bearing
Weightlessness Simulation / adverse effects*,  methods
Investigator
Investigator/Affiliation:
A A Pilmanis / Armstrong Lab, Brooks AFB, TX

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


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