title: Effects of pentobarbital on upper airway patency during sleep.
abstract: We hypothesised that pentobarbital would improve upper airway mechanics based on an increase in latency to arousal and amplitude of the phasic genioglossus electromyogram (EMG), and a decrease in the active upper airway critical closing pressure (P(crit)). 12 healthy subjects received pentobarbital (100 mg) or placebo in a double-blind, crossover protocol. During wakefulness, we measured the genioglossus reflex response to negative pressure pulses. During sleep, carbon dioxide was insufflated into the inspired air. Airway pressure was then decreased in a stepwise fashion until arousal from sleep. With basal breathing during sleep: flow rate was lower in volunteers given pentobarbital; end-tidal CO(2) concentration and upper airway resistance were greater; and P(crit) was unaffected (pentobarbital mean ± SD -11.7 ± 4.5 versus placebo -10.25 ± 3.6 cmH(2)O; p = 0.11). Pentobarbital increased the time to arousal (297 ± 63s versus 232 ± 67 s; p<0.05), at which time phasic genioglossus EMG was higher (6.2 ± 4.8% maximal versus 3.1 ± 3%; p<0.05) as were CO(2) levels. The increase in genioglossus EMG after CO(2) administration was greater after pentobarbital versus placebo. Pentobarbital did not affect the genioglossus negative-pressure reflex. Pentobarbital increases the time to arousal and stimulates genioglossus muscle activity, but it also increases upper airway resistance during sleep.
authors.affiliation: Dept of Anesthesia and Critical Care, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114-2696, USA. meikermann@partners.org
authors.forename: M
authors.initials: M
authors.lastname: Eikermann
authors.forename: D J
authors.initials: DJ
authors.lastname: Eckert
authors.forename: N L
authors.initials: NL
authors.lastname: Chamberlin
authors.forename: A S
authors.initials: AS
authors.lastname: Jordan
authors.forename: S
authors.initials: S
authors.lastname: Zaremba
authors.forename: S
authors.initials: S
authors.lastname: Smith
authors.forename: C
authors.initials: C
authors.lastname: Rosow
authors.forename: A
authors.initials: A
authors.lastname: Malhotra
mesh_terms: D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008168:Lung / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010424:Pentobarbital / Q000494:pharmacology*; D010919:Placebos; D012119:Respiration; D012893:Sleep Wake Disorders
chemical_list: D006993:Hypnotics and Sedatives; D010919:Placebos; D010424:Pentobarbital