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Effects of oxygen on exertional dyspnoea and exercise performance in patients with chronic obstructive pulmonary disease.
MedLine Citation:
PMID:  22008208     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
SUMMARY AT A GLANCE: Exercise responses under hyperoxic conditions in patients with COPD were investigated in a single-blind, randomized trial. Regardless of whether they were breathing compressed air or 24% O(2) , these patients did not develop ventilatory compensation in response to exertional acidosis and stopped exercising when a similar pH was reached. ABSTRACT: Background and objective:  The results of studies on the oxygen response in patients with COPD should provide important clues to the pathophysiology of exertional dyspnoea. We investigated the exercise responses to hyperoxia in relation to dyspnoea profile, as well as cardio-pulmonary, acidotic and sympathetic parameters in 35 patients with stable COPD (mean FEV(1) 46% predicted). Methods:  This was a single-blind trial, in which patients breathed 24% O(2) or compressed air (CA) in random order during two incremental cycle exercise tests. Results:  PaO(2) and PaCO(2) were higher (P < 0.0001 and P < 0.05, respectively) at each exercise point while patients were breathing 24% O(2) compared with CA. At a standardized time point near peak exercise, use of O(2) resulted in reduced plasma lactate and plasma noradrenaline concentrations (P < 0.01). Peak minute ventilation/indirect maximum voluntary ventilation was similar while breathing 24% O(2) and CA. At peak exercise, the dyspnoea score, pH and plasma noradrenaline concentrations were similar while breathing 24% O(2) and CA. The dyspnoea - ratio (%) of Δoxygen uptake (peak minus resting oxygen uptake) curve reached a break point that occurred at a similar exercise point while breathing 24% O(2) or CA. Conclusions:  Regardless of whether they breathed CA or 24% O(2) , patients with COPD did not develop ventilatory compensation for exertional acidosis, and the pH values measured were similar. Hyperoxia during a standardized exercise protocol did not alter the pattern of exertional dyspnoea in these patients, compared with breathing CA, although hyperoxia resulted in miscellaneous effects.
Authors:
Keisuke Miki; Ryoji Maekura; Toru Hiraga; Seigo Kitada; Mari Miki; Kenji Yoshimura; Yoshitaka Tateishi
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-18
Journal Detail:
Title:  Respirology (Carlton, Vic.)     Volume:  -     ISSN:  1440-1843     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-10-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9616368     Medline TA:  Respirology     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2011 The Authors. Respirology © 2011 Asian Pacific Society of Respirology.
Affiliation:
Department of Internal medicine, National Hospital Organization Toneyama National Hospital, Toyonaka, Osaka, Japan.
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