• Jeroen C P Simons, Eric Pierce, Daniel Diaz-Gil, Sanjana A Malviya, Matthew J Meyer, Fanny P Timm, Janne B Stokholm, Carl E Rosow, Robert M Kacmarek, and Matthias Eikermann.
• From the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts (J.C.P.S., E.P., D.D.-.G., S.A.M., M.J.M., F.P.T., J.B.S., C.E.R., R.M.K., M.E.); Department of Orthopaedic and Trauma Surgery, University of Cologne, Cologne, Germany (J.C.P.S.); Department of Anesthesiology, University of Copenhagen, Herlev Hospital, Copenhagen, Denmark (J.B.S.); Department of Respiratory Care, Harvard Medical School, Boston, Massachusetts (R.M.K.); and Department of Anesthesia and Critical Care, University of Essen, Essen, Germany (M.E.).
• Anesthesiology. 2016 Sep 1; 125 (3): 525-34.

BackgroundVolatile anesthetics and propofol impair upper airway stability and possibly respiratory upper airway dilator muscle activity. The magnitudes of these effects have not been compared at equivalent anesthetic doses. We hypothesized that upper airway closing pressure is less negative and genioglossus activity is lower during deep compared with shallow anesthesia.MethodsIn a randomized controlled crossover study of 12 volunteers, anesthesia with propofol or sevoflurane was titrated using a pain stimulus to identify the threshold for suppression of motor response to electrical stimulation. Measurements included bispectral index, genioglossus electromyography, ventilation, hypopharyngeal pressure, upper airway closing pressure, and change in end-expiratory lung volume during mask pressure drops.ResultsA total of 393 attempted breaths during occlusion maneuvers were analyzed. Upper airway closing pressure was significantly less negative at deep versus shallow anesthesia (-10.8 ± 4.5 vs. -11.3 ± 4.4 cm H2O, respectively [mean ± SD]) and correlated with the bispectral index (P < 0.001), indicating a more collapsible airway at deep anesthesia. Respiratory genioglossus activity during airway occlusion was significantly lower at deep compared with light anesthesia (26 ± 21 vs. 35 ± 24% of maximal genioglossus activation, respectively; P < 0.001) and correlated with bispectral index (P < 0.001). Upper airway closing pressure and genioglossus activity during airway occlusion did not differ between sevoflurane and propofol anesthesia.ConclusionsPropofol and sevoflurane anesthesia increased upper airway collapsibility in a dose-dependent fashion with no difference at equivalent anesthetic concentrations. These effects can in part be explained by a dose-dependent inhibiting effect of anesthetics on respiratory genioglossus activity.

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