title: Genioglossal activation in patients with obstructive sleep apnea versus control subjects. Mechanisms of muscle control.
abstract: Pharyngeal dilator muscle activation (GGEMG) during wakefulness is greater in patients with obstructive sleep apnea (OSA) than in healthy control subjects, representing a neuromuscular compensatory mechanism for a more collapsible airway. As previous work from our laboratory has demonstrated a close relationship between GGEMG and epiglottic pressure, we examined the relationship between genioglossal activity and epiglottic pressure in patients with apnea and in control subjects across a wide range of epiglottic pressures during basal breathing, negative-pressure (iron-lung) ventilation, heliox breathing, and inspiratory resistive loading. GGEMG was greater in the patients with apnea under all conditions (p < 0.05 for all comparisons), including tonic, phasic, and peak phasic GGEMG. In addition, patients with apnea generated a greater peak epiglottic pressure on a breath-by-breath basis. Although the relationship between GGEMG and epiglottic negative pressure was tight across all conditions in both groups (all R values > = 0.69), there were no significant differences in the slope of this relationship between the two groups (all p values > 0.30) under any condition. Thus, the increased GGEMG seen in the patient with apnea during wakefulness appears to be a product of an increased tonic activation of the muscle, combined with increased negative-pressure generation during inspiration.
authors.affiliation: Divisions of Sleep Medicine and Pulmonary and Critical Care, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. rfogel@partners.org
authors.forename: R B
authors.initials: RB
authors.lastname: Fogel
authors.forename: A
authors.initials: A
authors.lastname: Malhotra
authors.forename: G
authors.initials: G
authors.lastname: Pillar
authors.forename: J K
authors.initials: JK
authors.lastname: Edwards
authors.forename: J
authors.initials: J
authors.lastname: Beauregard
authors.forename: S A
authors.initials: SA
authors.lastname: Shea
authors.forename: D P
authors.initials: DP
authors.lastname: White
mesh_terms: D000403:Airway Resistance / Q000502:physiology; D000704:Analysis of Variance; D016022:Case-Control Studies; D004576:Electromyography; D004825:Epiglottis / Q000502:physiology / Q000503:physiopathology; D006371:Helium / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000494:pharmacology; D010366:Peak Expiratory Flow Rate; D010609:Pharyngeal Muscles / Q000502:physiology* / Q000503:physiopathology*; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*; D014059:Tongue / Q000502:physiology* / Q000503:physiopathology*; D015919:Ventilators, Negative-Pressure
chemical_list: D006371:Helium; C038949:heliox; D010100:Oxygen