Document Detail

Dependency on the rate of change in PaO2 of the ventilatory response to progressive hypoxia.
MedLine Citation:
PMID:  7767525     Owner:  NLM     Status:  MEDLINE    
The biphasic nature of the ventilatory response to sustained hypoxia (< 1 h) is thought to occur as a result of combined effects of stimulation and depression with hypoxia. If the depressant effect of hypoxia on ventilation occurs later than the stimulatory effect, the magnitude of the ventilatory response to progressive hypoxia may be different according to the time required for a given fall in PaO2 during the test. In this study, we measured, in 10 healthy adult volunteers, ventilatory responses to isocapnic progressive hypoxia (HVR) using three different protocols (4 min, 6 min, and 15 min for SaO2 to decrease from the baseline to 80%) with or without pretreatment using theophylline (300 mg twice a day), an adenosine receptor antagonist, in a 2-d, single-blind crossover design. The slope values of HVR with the placebo were 0.31 +/- 0.04 (SE) (L/min/% fall of SaO2) in the 4-min protocol, 0.26 +/- 0.04 in the 6-min protocol, and 0.18 +/- 0.04 in the 15-min protocol. The HVR for the 15-min protocol was significantly lower than that for the 4-min or 6-min protocol. The HVR with theophylline was 0.46 +/- 0.08 for the 4-min protocol, 0.54 +/- 0.09 for the 6-min protocol, and 0.66 +/- 0.11 for the 15-min protocol, among which there were no significant differences. The dependency of HVR on the rate of change in PaO2, that was seen with a placebo run, disappeared after pretreatment with theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)
T Igarashi; M Nishimura; S Kobayashi; K Miyamoto; Y Kawakami
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  151     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-06-30     Completed Date:  1995-06-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1815-20     Citation Subset:  AIM; IM    
First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
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MeSH Terms
Adenosine / physiology*
Anoxia / physiopathology*
Chemoreceptor Cells / drug effects
Cross-Over Studies
Oxygen / blood*
Partial Pressure
Pulmonary Gas Exchange / physiology
Receptors, Purinergic P1 / antagonists & inhibitors
Single-Blind Method
Theophylline / pharmacology*
Time Factors
Reg. No./Substance:
0/Receptors, Purinergic P1; 58-55-9/Theophylline; 58-61-7/Adenosine; 7782-44-7/Oxygen

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