Document Detail

The effects of breath-holds and Muller manoeuvres on upper airway carbon dioxide concentration in humans.
MedLine Citation:
PMID:  17259692     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Obstructive sleep apnoea is caused by collapse of the upper airway. The presence of CO(2) in the upper airway lumen evokes a number of reflexes which favour upper airway re-opening, and we have proposed previously that CO(2) would build up in the upper airway following airway collapse and that this would contribute to reflex airway re-opening. However, it is not known if CO(2) can transfer from the alveoli to the anatomical dead space of the upper airway during apnoea. OBJECTIVES: To determine if alveolar CO(2) can enter the upper airway during breath-holds and Muller manoeuvres. MATERIAL AND METHODS: With local ethics committee approval, 6 male volunteers (aged 22-48 years), following a quiet inspiration, carried out breath-holds and Muller manoeuvres until breaking point. CO(2) was measured continuously in samples obtained from the hypopharynx using an infrared analyser with a sample rate of 50 ml/min. Muller manoeuvres (forced inspirations against a closed upper airway) mimic the respiratory efforts which occur during obstructive apnoeas. RESULTS: In all cases, CO(2) increased progressively during apnoeas. There was a much larger increase in Muller manoeuvres (3.78 +/- 0.51%, mean +/- SEM at breaking point) compared to breath-holds. DISCUSSION: These results show that upper airway CO(2) concentration rises substantially during apnoeas and suggest that transfer of CO(2) from the lungs to the upper airway may evoke a number of reflex effects which could affect breathing and upper airway re-opening during obstructive apnoeas.
A Raza; T Farrell; K D O'Halloran; A Bradford
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-01-24
Journal Detail:
Title:  Respiration; international review of thoracic diseases     Volume:  74     ISSN:  0025-7931     ISO Abbreviation:  Respiration     Publication Date:  2007  
Date Detail:
Created Date:  2007-08-02     Completed Date:  2007-10-23     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0137356     Medline TA:  Respiration     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  533-6     Citation Subset:  IM    
Copyright Information:
Copyright 2007 S. Karger AG, Basel.
Department of Anatomy, Royal College of Surgeons in Ireland, University College Dublin, Dublin, Ireland.
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MeSH Terms
Carbon Dioxide / metabolism*
Hypopharynx / physiology
Middle Aged
Pulmonary Ventilation / physiology
Respiratory Dead Space / physiology
Sleep Apnea, Obstructive / metabolism*,  physiopathology
Reg. No./Substance:
124-38-9/Carbon Dioxide

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