Document Detail

Changes in respiratory control during and after 48 h of isocapnic and poikilocapnic hypoxia in humans.
MedLine Citation:
PMID:  9843535     Owner:  NLM     Status:  MEDLINE    
Ventilatory acclimatization to hypoxia is associated with an increase in ventilation under conditions of acute hyperoxia (VEhyperoxia) and an increase in acute hypoxic ventilatory response (AHVR). This study compares 48-h exposures to isocapnic hypoxia (protocol I) with 48-h exposures to poikilocapnic hypoxia (protocol P) in 10 subjects to assess the importance of hypocapnic alkalosis in generating the changes observed in ventilatory acclimatization to hypoxia. During both hypoxic exposures, end-tidal PO2 was maintained at 60 Torr, with end-tidal PCO2 held at the subject's prehypoxic level (protocol I) or uncontrolled (protocol P). VEhyperoxia and AHVR were assessed regularly throughout the exposures. VEhyperoxia (P < 0.001, ANOVA) and AHVR (P < 0.001) increased during the hypoxic exposures, with no significant differences between protocols I and P. The increase in VEhyperoxia was associated with an increase in slope of the ventilation-end-tidal PCO2 response (P < 0.001) with no significant change in intercept. These results suggest that changes in respiratory control early in ventilatory acclimatization to hypoxia result from the effects of hypoxia per se and not the alkalosis normally accompanying hypoxia.
J G Tansley; M Fatemian; L S Howard; M J Poulin; P A Robbins
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  85     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1998 Dec 
Date Detail:
Created Date:  1999-02-01     Completed Date:  1999-02-01     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2125-34     Citation Subset:  IM    
University Laboratory of Physiology, University of Oxford, Oxford OX1 3PT, United Kingdom.
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MeSH Terms
Acclimatization / physiology
Acid-Base Equilibrium
Alkalosis / blood,  physiopathology
Anoxia / blood,  physiopathology*
Carbon Dioxide / blood*
Hydrogen-Ion Concentration
Hyperventilation / physiopathology
Respiratory Mechanics / physiology*
Time Factors
Grant Support
//Wellcome Trust
Reg. No./Substance:
124-38-9/Carbon Dioxide

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