Document Detail

Genioglossus activity available via non-arousal mechanisms vs. that required for opening the airway in obstructive apnea patients.
MedLine Citation:
PMID:  21921245     Owner:  NLM     Status:  MEDLINE    
It is generally believed that reflex recruitment of pharyngeal dilator muscles is insufficient to open the airway of obstructive apnea (OSA) patients once it is closed and, therefore, that arousal is required. Yet arousal promotes recurrence of obstruction. There is no information about how much dilator [genioglossus (GG)] activation is required to open the airway (GG Opening Threshold) or about the capacity of reflex mechanisms to increase dilator activity before/without arousal (Non-Arousal Activation). The relationship between these two variables is important for ventilatory stability. We measured both variables in 32 OSA patients (apnea-hypopnea index 74 ± 42 events/h). GG activity was monitored while patients were on optimal continuous positive airway pressure (CPAP). Zopiclone was administered to delay arousal. Maximum GG activity (GG(MAX)) and airway closing pressure (P(CRIT)) were measured. During stable sleep CPAP was decreased to 1 cmH(2)O to induce obstructive events and the dial-downs were maintained until the airway opened with or without arousal. GG activity at the instant of opening (GG Opening Threshold) was measured. GG Opening Threshold averaged only 10.4 ± 9.5% GG(Max) and did not correlate with P(CRIT) (r = 0.04). Twenty-six patients had >3 openings without arousal, indicating that Non-Arousal Activation can exceed GG Opening Threshold in the majority of patients. GG activity reached before arousal in Arousal-Associated Openings was only 5.4 ± 4.6% GG(MAX) below GG Opening Threshold. We conclude that in most patients GG activity required to open the airway is modest and can be reached by non-arousal mechanisms. Arousals occur in most cases just before non-arousal mechanisms manage to increase activity above GG Opening Threshold. Measures to reduce GG Opening Threshold even slightly may help stabilize breathing in many patients.
Magdy Younes; Andrea H S Loewen; Michele Ostrowski; John Laprairie; Frances Maturino; Patrick J Hanly
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-09-15
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  112     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-18     Completed Date:  2013-07-08     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:  249-58     Citation Subset:  IM    
Sleep Center, Foothills Medical Centre, University of Calgary, Calgary, Alberta, Canada.
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MeSH Terms
Airway Obstruction / drug therapy*,  physiopathology
Arousal / drug effects*
Azabicyclo Compounds / therapeutic use*
Hypnotics and Sedatives / therapeutic use*
Middle Aged
Pharyngeal Muscles / drug effects*,  physiopathology
Piperazines / therapeutic use*
Sleep Apnea, Obstructive / complications,  drug therapy*,  physiopathology
Stimulation, Chemical
Grant Support
//Canadian Institutes of Health Research
Reg. No./Substance:
0/Azabicyclo Compounds; 0/Hypnotics and Sedatives; 0/Piperazines; 43200-80-2/zopiclone
Comment In:
J Appl Physiol (1985). 2012 Jan;112(2):247-8   [PMID:  22033535 ]

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

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