Document Detail

A quick and easy method of measuring the hypercapnic ventilatory response in patients with COPD.
MedLine Citation:
PMID:  18842399     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Hypercapnic ventilatory response (HCVR) techniques have not previously been adequately validated in patients with chronic obstructive pulmonary disease (COPD). We have tested the hypothesis that end-tidal PCO(2) may be used to test the HCVR in COPD during non-steady-state rebreathing, despite the fact that large (arterial-end-tidal) PCO(2) differences (P(a-et)CO(2)) exist during air breathing. METHODS: Eight patients and 11 healthy volunteers underwent steady-state HCVR testing and non-steady-state rebreathing HCVR testing, using Pa and PetCO(2). RESULTS: In COPD patients, PetCO(2) was lower than PaCO(2) by a constant amount throughout steady-state HCVR, but equalised with PaCO(2) during non-steady-state HCVR. Consequently there were no differences in HCVR slope using either method (steady-state p=0.91; rebreathing p=0.73), or HCVR intercept in rebreathing (p=0.68) whether PaCO(2) or PetCO(2) was used. The steady-state HCVR intercept using PetCO(2) was greater than that using PaCO(2) (p=0.02). In healthy volunteers PetCO(2) equalised with PaCO(2) during steady-state HCVR, but was progressively greater than PaCO(2) during non-steady-state. Consequently, there was no difference in HCVR slope (p=0.21) or intercept (p=0.46) whether PaCO(2) or PetCO(2) was used. During non-steady-state there was a P(a-et)CO(2) difference in slope (p=0.03) and intercept (p=0.04). CONCLUSIONS: In COPD patients non-steady-state HCVR using PetCO(2) is well tolerated, which is as accurate as PaCO(2). HCVR slope may be derived using PetCO(2) during steady-state testing, though there may be errors in intercept compared to use of PaCO(2). In healthy volunteers PetCO(2) may be used to estimate PaCO(2) during steady-state but not rebreathing HCVR.
Annabel H Nickol; Helen Dunroy; Michael I Polkey; Anita Simonds; Jeremy Cordingley; Douglas R Corfield; Mary J Morrell
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-10-07
Journal Detail:
Title:  Respiratory medicine     Volume:  103     ISSN:  1532-3064     ISO Abbreviation:  Respir Med     Publication Date:  2009 Feb 
Date Detail:
Created Date:  2009-01-23     Completed Date:  2009-03-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8908438     Medline TA:  Respir Med     Country:  England    
Other Details:
Languages:  eng     Pagination:  258-67     Citation Subset:  IM    
Clinical and Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Royal Brompton Hospital, Fulham Road, London SW3 6NP, UK.
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MeSH Terms
Breath Tests / methods
Carbon Dioxide / physiology*
Hypercapnia / physiopathology*
Middle Aged
Pulmonary Disease, Chronic Obstructive / physiopathology*
Tidal Volume / physiology
Ventilation-Perfusion Ratio / physiology*
Grant Support
//Wellcome Trust
Reg. No./Substance:
124-38-9/Carbon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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