• Shinji Kurata, Takurou Sanuki, Ichiro Okayasu, Mari Kawai, Shunji Moromugi, and Takao Ayuse.
• Department of Dental Anesthesiology, Nagasaki University Hospital, Nagasaki, Japan.
• J Clin Anesth. 2016 Mar 1; 29: 75-82.

Study ObjectiveTo test the hypothesis that the jaw closure using a pneumatic actuator device affect airway collapsibility and resistance during propofol anesthesia.DesignProspective, randomized study.SettingUniversity-affiliated hospital.PatientsSix male subjects were included in the present study.InterventionWe used pressure-flow relationships to evaluate critical closing pressure (PCRIT) and upper airway resistance in different conditions of body and head position. Anesthesia was induced and maintained with a propofol infusion, targeting a constant blood concentration of 1.5 to 2.0μg/mL to establish an adequate depth of anesthesia, with patients breathing spontaneously through a nasal mask. An air-inflatable pneumatic actuator was used to achieve jaw closure. Nasal mask pressure was intermittently reduced to evaluate upper airway collapsibility (passive PCRIT) and upstream resistance under 4 different conditions: (1) neutral occlusion at 0-cm head elevation (baseline), (2) jaw closure at 0-cm head elevation, (3) neutral occlusion at 6-cm head elevation, and (4) jaw closure at 6-cm head elevation. PCRIT and upstream resistance under each condition were compared using 1-way analysis of variance. P<.05 was considered significant.MeasurementsThe pressure and inspiratory flow at the subjects' nose mask were recorded. Polysomonographic parameters (electroencephalograms, electrooculograms, submental electromyograms, and plethysmogram) were also recorded.Main ResultsThe combination of 6-cm head elevation with jaw closure using the pneumatic actuator decreased upper airway collapsibility (PCRIT≈-3.0 cm H2O) compared to the baseline position (PCRIT≈-1.2 cm H2O; P=.0003).ConclusionWe demonstrated that jaw closure using an air-inflatable pneumatic actuator device can produce substantial decreases in upper airway collapsibility and maintain upper airway patency during propofol anesthesia.Copyright © 2016 Elsevier Inc. All rights reserved.

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