Document Detail

Autonomic response to hypobaric hypoxia assessed by time-dependent frequency decomposition of heart rate.
MedLine Citation:
PMID:  11718519     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Acute hypoxia tolerance varies substantially among healthy individuals. We hypothesized that this variability results from a difference in autonomic (ANS) response to hypoxic stress. METHODS: Peripheral oxygen saturation, respiration and ECG were recorded from 21 healthy subjects (age, 29 +/- 7 yr) in an altitude chamber during normoxia, severe hypoxia (282 mm Hg), and mild hypoxia (360 mm Hg). Cardiovascular control was assessed by time-frequency decomposition of the heart rate signal applying the Selective Discrete Transform Algorithm (SDA). This procedure uses a variable time window, thus providing reliable physiological data even during transient states. Autonomic activity was quantified by power spectral density integrals over a 3-dimensional time-dependent spectral distribution of heart rate fluctuations. RESULTS: Subjects who had slower peripheral oxygen desaturation during severe hypoxia onset (mean 92.9 vs. 58.4 s) were those who displayed higher ANS activity in all ambient states, namely normoxia and hypoxia. These same subjects withstood hypoxia for significantly longer time periods (mean 313 vs. 244 s). CONCLUSION: Improved hypoxia tolerance is linked to enhanced autonomic activity, involving a better management of peripheral blood flow.
Y Barak; D David; L Keselbrener; S Akselrod
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  72     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2001 Nov 
Date Detail:
Created Date:  2001-11-22     Completed Date:  2002-03-01     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  992-1000     Citation Subset:  IM; S    
Abramson Center for Medical Physics, School of Physics, Tel-Aviv University, Israel.
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MeSH Terms
Anoxia / blood,  physiopathology*
Autonomic Nervous System / physiopathology*
Heart Rate*
Oxygen / blood
Stress, Physiological / physiopathology
Reg. No./Substance:

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