| Genioglossus Activity Available via Non-arousal Mechanisms vs. that Required for Opening the Airway in Obstructive Apnea Patients. | |
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MedLine Citation:
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PMID: 21921245 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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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±42hr(-1)). GG activity was monitored while patients were on optimal Continuous-Positive-Airway-Pressure (CPAP). Zopiclone was administered to delay arousal. Maximum GG activity (GGMAX) 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. |
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Authors:
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Magdy Younes; Andrea H S Loewen; Michele Ostrowski; John Laprairie; Frances Maturino; Patrick J Hanly |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-9-15 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-9-16 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Calgary. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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