Perioperative Medicine  |   July 2018
Supplemental Carbon Dioxide Stabilizes the Upper Airway in Volunteers Anesthetized with Propofol
Author Notes
  • From the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (K.J.R., H.D., T.H.); Department of Anesthesiology, Herlev and Gentofte Hospital, Herlev, Denmark (J.B.S.); Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Hospital, Boston, Massachusetts (J.Patlak, M.E.); Helios Klinikum Krefeld, Klinik für Orthopädie, Unfall- und Handchirurgie, Krefeld, Germany (J.C.R.S.); and Klinik für Anäesthesiologie und Intensivmedizin, Universität Duisburg Essen and Universitätsklinikum Essen, Essen, Germany (J.Peters, M.E.).
  • Part of the work presented in this article has been presented as an abstract at the Anesthesiology Annual Meeting Best of Abstracts: Clinical Science, October 22 to 26, 2016, Chicago, Illinois. K.J.R. and J.B.S. contributed equally to this article.
    Part of the work presented in this article has been presented as an abstract at the Anesthesiology Annual Meeting Best of Abstracts: Clinical Science, October 22 to 26, 2016, Chicago, Illinois. K.J.R. and J.B.S. contributed equally to this article.×
  • Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).
    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • Submitted for publication November 13, 2017. Accepted for publication March 19, 2018.
    Submitted for publication November 13, 2017. Accepted for publication March 19, 2018.×
  • Address correspondence to Dr. Eikermann: Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, Massachusetts 02215. meikerma@bidmc.harvard.edu. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Perioperative Medicine / Clinical Science / Airway Management / Gastrointestinal and Hepatic Systems / Pharmacology / Respiratory System
Perioperative Medicine   |   July 2018
Supplemental Carbon Dioxide Stabilizes the Upper Airway in Volunteers Anesthetized with Propofol
Anesthesiology 7 2018, Vol.129, 37-46. doi:10.1097/ALN.0000000000002239
Anesthesiology 7 2018, Vol.129, 37-46. doi:10.1097/ALN.0000000000002239
Abstract

Background: Propofol impairs upper airway dilator muscle tone and increases upper airway collapsibility. Preclinical studies show that carbon dioxide decreases propofol-mediated respiratory depression. We studied whether elevation of end-tidal carbon dioxide (Petco2) via carbon dioxide insufflation reverses the airway collapsibility (primary hypothesis) and impaired genioglossus muscle electromyogram that accompany propofol anesthesia.

Methods: We present a prespecified, secondary analysis of previously published experiments in 12 volunteers breathing via a high-flow respiratory circuit used to control upper airway pressure under propofol anesthesia at two levels, with the deep level titrated to suppression of motor response. Ventilation, mask pressure, negative pharyngeal pressure, upper airway closing pressure, genioglossus electromyogram, bispectral index, and change in end-expiratory lung volume were measured as a function of elevation of Petco2 above baseline and depth of propofol anesthesia.

Results: Petco2 augmentation dose-dependently lowered upper airway closing pressure with a decrease of 3.1 cm H2O (95% CI, 2.2 to 3.9; P < 0.001) under deep anesthesia, indicating improved upper airway stability. In parallel, the phasic genioglossus electromyogram increased by 28% (23 to 34; P < 0.001). We found that genioglossus electromyogram activity was a significant modifier of the effect of Petco2 elevation on closing pressure (P = 0.005 for interaction term).

Conclusions: Upper airway collapsibility induced by propofol anesthesia can be reversed in a dose-dependent manner by insufflation of supplemental carbon dioxide. This effect is at least partly mediated by increased genioglossus muscle activity.