Document Detail

Modeling the effects of exercise during 100% oxygen prebreathe on the risk of hypobaric decompression sickness.
MedLine Citation:
PMID:  9056027     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Several previous studies indicated that exercise during prebreathe with 100% O2 decreased the incidence of hypobaric decompression sickness (DCS). We report a meta-analysis of these investigations combined with a new study in our laboratory to develop a statistical model as a predictive tool for DCS. HYPOTHESIS: Exercise during prebreathe increases N2 elimination in a theoretical 360-min half-time compartment decreasing the incidence of DCS. METHODS: A dose-response probability tissue ratio (TR) model with 95% confidence limits was created for two groups, prebreathe with exercise (n = 113) and resting prebreathe (n = 113), using nonlinear regression analysis with maximum likelihood optimization. RESULTS: The model predicted that prebreathe exercise would reduce the residual N2 in a 360-min half-time compartment to a level analogous to that in a 180-min compartment. This finding supported the hypothesis. The incidence of DCS for the exercise prebreathe group was significantly decreased (Chi-Square = 17.1, p < 0.0001) from the resting prebreathe group. CONCLUSIONS: The results suggested that exercise during prebreathe increases tissue perfusion and N2 elimination approximately 2-fold and markedly lowers the risk of DCS. Based on the model, the prebreathe duration may be reduced from 240 min to a predicted 91 min for the protocol in our study, but this remains to be verified. The model provides a useful planning tool to develop and test appropriate prebreathe exercise protocols and to predict DCS risks for astronauts.
K C Loftin; J Conkin; M R Powell
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Publication Detail:
Type:  Journal Article; Meta-Analysis; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  68     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  1997 Mar 
Date Detail:
Created Date:  1997-05-15     Completed Date:  1997-05-15     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:  199-204     Citation Subset:  IM; S    
KRUG Life Sciences Inc., Houston, TX 77058, USA.
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MeSH Terms
Clinical Protocols
Decompression Sickness / etiology,  prevention & control*
Dose-Response Relationship, Drug
Exercise Therapy / methods*
Likelihood Functions
Oxygen Inhalation Therapy / methods*
Predictive Value of Tests
Regression Analysis
Reproducibility of Results
Time Factors
Tissue Distribution
M R Powell / JSC

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

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