title: The compensatory responses to upper airway obstruction in normal subjects under propofol anesthesia.
abstract: Upper airway obstruction during sleep can trigger compensatory neuromuscular responses and/or prolong inspiration in order to maintain adequate minute ventilation. The aim of this study was to investigate the strength of these compensatory responses during upper airway obstruction during propofol anesthesia. We assessed respiratory timing and upper airway responses to decreases in nasal pressure in nine propofol anesthetized normal subjects under condition of decreased (passive) and increased (active) neuromuscular activity. Critical closing pressure (PCRIT) and upstream resistance (RUS) were derived from pressure-flow relationships generated from each condition. The inspiratory duty cycle (IDC), maximum inspiratory flow (V1max) and respiratory rate (f) were determined at two levels of mean inspiratory airflow (VI; mild airflow limitation with VI > or = 150 ml s-1; severe airflow limitation with VI < 150 ml s-1). Compared to the passive condition, PCRIT decreased significantly (5.3 +/- 3.8 cm H2O, p < 0.05) and RUS increased (7.4 cm H2O ml-1 s, p < 0.05) in the active condition. The IDC increased progressively and comparably as decreased in both the passive and active conditions (p < 0.05). These findings imply that distinct compensatory mechanisms govern the modulation of respiratory pattern and pharyngeal patency during periods of airway obstruction under propofol anesthesia.
authors.affiliation: Nagasaki University of Graduate School of Biomedical Sciences, Course of Medical and Dental Sciences, Department of Translational Medical Sciences, Division of Clinical Physiology, Nagasaki, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Takao
authors.initials: T
authors.lastname: Ayuse
authors.forename: Shinji
authors.initials: S
authors.lastname: Kurata
authors.forename: Terumi
authors.initials: T
authors.lastname: Ayuse
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schneider
authors.forename: Jason P
authors.initials: JP
authors.lastname: Kirkness
authors.forename: Susheel P
authors.initials: SP
authors.lastname: Patil
authors.forename: Alan R
authors.initials: AR
authors.lastname: Schwartz
authors.forename: Kumiko
authors.initials: K
authors.lastname: Oi
mesh_terms: D000293:Adolescent; D000328:Adult; D000402:Airway Obstruction / Q000503:physiopathology*; D000403:Airway Resistance / Q000187:drug effects*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D010614:Pharynx / Q000502:physiology; D011175:Positive-Pressure Respiration; D015742:Propofol / Q000494:pharmacology*; D015656:Respiratory Mechanics / Q000187:drug effects*; D012132:Respiratory Muscles / Q000294:innervation; D013997:Time Factors; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol