Affordable Access

deepdyve-link
Publisher Website

Genioglossus activity available via non-arousal mechanisms vs. that required for opening the airway in obstructive apnea patients.

Authors
  • Younes, Magdy
  • Loewen, Andrea H S
  • Ostrowski, Michele
  • Laprairie, John
  • Maturino, Frances
  • Hanly, Patrick J
Type
Published Article
Journal
Journal of Applied Physiology
Publisher
American Physiological Society
Publication Date
Jan 01, 2012
Volume
112
Issue
2
Pages
249–258
Identifiers
DOI: 10.1152/japplphysiol.00312.2011
PMID: 21921245
Source
Medline
License
Unknown

Abstract

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.

Report this publication

Statistics

Seen <100 times