Document Detail


Nocturnal periodic breathing during acclimatization at very high altitude at Mount Muztagh Ata (7,546 m).
MedLine Citation:
PMID:  20442435     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
RATIONALE: Quantitative data on ventilation during acclimatization at very high altitude are scant. Therefore, we monitored nocturnal ventilation and oxygen saturation in mountaineers ascending Mt. Muztagh Ata (7,546 m). OBJECTIVES: To investigate whether periodic breathing persists during prolonged stay at very high altitude. METHODS: A total of 34 mountaineers (median age, 46 yr; 7 women) climbed from 3,750 m within 19-20 days to the summit at 7,546 m. During ascent, repeated nocturnal recordings of calibrated respiratory inductive plethysmography, pulse oximetry, and scores of acute mountain sickness were obtained. MEASUREMENTS AND MAIN RESULTS: Nocturnal oxygen saturation decreased, whereas minute ventilation and the number of periodic breathing cycles increased with increasing altitude. At the highest camp (6,850 m), median nocturnal oxygen saturation, minute ventilation, and the number of periodic breathing cycles were 64%, 11.3 L/min, and 132.3 cycles/h. Repeated recordings within 5-8 days at 4,497 m and 5,533 m, respectively, revealed increased oxygen saturation, but no decrease in periodic breathing. The number of periodic breathing cycles was positively correlated with days of acclimatization, even when controlled for altitude, oxygen saturation, and other potential confounders, whereas symptoms of acute mountain sickness had no independent effect on periodic breathing. CONCLUSIONS: Our field study provides novel data on nocturnal oxygen saturation, breathing patterns, and ventilation at very high altitude. It demonstrates that periodic breathing increases during acclimatization over 2 weeks at altitudes greater than 3,730 m, despite improved oxygen saturation consistent with a progressive increase in loop gain of the respiratory control system. Clinical trial registered with www.clinicaltrials.gov (NCT00514826).
Authors:
Konrad E Bloch; Tsogyal D Latshang; Alexander J Turk; Thomas Hess; Urs Hefti; Tobias M Merz; Martina M Bosch; Daniel Barthelmes; Jacqueline Pichler Hefti; Marco Maggiorini; Otto D Schoch
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-04
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  182     ISSN:  1535-4970     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-17     Completed Date:  2010-09-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  562-8     Citation Subset:  AIM; IM    
Affiliation:
Department of Internal Medicine, University Hospital of Zurich, Zurich Centre for Integrative Human Physiology, University of Zurich, Switzerland. konrad.bloch@usz.ch
Data Bank Information
Bank Name/Acc. No.:
ClinicalTrials.gov/NCT00514826
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / physiology*
Adult
Aged
Altitude Sickness / complications,  diagnosis,  physiopathology
Anoxia / complications,  diagnosis,  physiopathology
China
Female
Humans
Male
Middle Aged
Mountaineering / physiology*
Oximetry / methods
Oxygen Consumption / physiology
Plethysmography / methods,  statistics & numerical data
Polysomnography / methods,  statistics & numerical data
Respiration*
Sleep Apnea, Central / complications,  diagnosis,  physiopathology

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