title: Influence of pharyngeal muscle activity on inspiratory negative effort dependence in the human upper airway.
abstract: The upper airway is often modeled as a Starling resistor, which predicts that flow is independent of inspiratory effort during flow limitation. However, while some obstructive sleep apnea (OSA) patients exhibit flat, Starling resistor-like flow limitation, others demonstrate considerable negative effort dependence (NED), defined as the percent reduction in flow from peak to mid-inspiration. We hypothesized that the variability in NED could be due to differences in phasic pharyngeal muscle activation between individuals. Therefore, we induced topical pharyngeal anesthesia to reduce phasic pharyngeal muscle activation to see if it increased NED. Twelve subjects aged 50±10 years with a BMI of 35±6 kg/m(2) and severe OSA (apnea-hypopnea index=52±28 events/h) were studied. NED and phasic genioglossus muscle activity (EMG(GG)) of flow limited breaths were determined before and after pharyngeal anesthesia with lidocaine. Pharyngeal anesthesia led to a 33% reduction in EMG(GG) activity (p<0.001), but NED worsened only by 3.6±5.8% (p=0.056). In conclusion, phasic EMG(GG) had little effect on NED. This finding suggests that individual differences in phasic EMG(GG) activation do not likely explain the variability in NED found among OSA patients.
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA. Electronic address: prgenta@gmail.com.
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Genta
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Owens
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Edwards
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sands
authors.affiliation: Neuroscience Research Australia (NeuRA) and the School of Medical Sciences, University of New South Wales, NSW 2052, Sydney, Australia.
authors.forename: Danny J
authors.initials: DJ
authors.lastname: Eckert
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: James P
authors.initials: JP
authors.lastname: Butler
authors.affiliation: Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Loring
authors.affiliation: Pulmonary and Critical Care Medicine, University of California San Diego, 9300 Campus Point Drive, La Jolla, CA 92037, USA.
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.affiliation: Department of Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jackson
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: White
authors.affiliation: Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wellman
mesh_terms: D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D000779:Anesthetics, Local / Q000494:pharmacology; D045422:Continuous Positive Airway Pressure; D004576:Electromyography; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D010609:Pharyngeal Muscles / Q000187:drug effects / Q000503:physiopathology*; D010614:Pharynx / Q000294:innervation; D020181:Sleep Apnea, Obstructive / Q000473:pathology* / Q000628:therapy; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine
keywords: Eletromyography; Flow limitation; Genioglossus; Negative effort dependence; Obstructive sleep apnea; Starling resistor