Newly Published
Critical Care Medicine  |   May 2018
Respiratory Muscle Effort during Expiration in Successful and Failed Weaning from Mechanical Ventilation
Author Notes
  • From the Departments of Critical Care Medicine (J.D., L.H.R., J.G.v.d.H., L.M.A.H.), Anesthesiology (D.J.), and Pulmonary Diseases (H.W.H.v.H.) and the Donders Institute for Brain, Cognition and Behaviour, Department of Neurology (J.D.), Radboud University Medical Center, Nijmegen, The Netherlands; and the Department of Intensive Care Medicine, VU University Medical Center, Amsterdam, The Netherlands (L.M.A.H.).
  • 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 March 22, 2017. Accepted for publication April 11, 2018.
    Submitted for publication March 22, 2017. Accepted for publication April 11, 2018.×
  • Acknowledgments: The authors thank Wiebe Pestman, Ph.D. (Department of Biostatistics, Radboud University Medical Center, Nijmegen, The Netherlands), for his statistical advice and review of the manuscript.
    Acknowledgments: The authors thank Wiebe Pestman, Ph.D. (Department of Biostatistics, Radboud University Medical Center, Nijmegen, The Netherlands), for his statistical advice and review of the manuscript.×
  • Research Support: This study was investigator-initiated and financed by institutional resources (Department of Critical Care Medicine, Radboud University Medical Center, Nijmegen, The Netherlands).
    Research Support: This study was investigator-initiated and financed by institutional resources (Department of Critical Care Medicine, Radboud University Medical Center, Nijmegen, The Netherlands).×
  • Competing Interests: The authors declare no competing interests.
    Competing Interests: The authors declare no competing interests.×
  • Correspondence: Address correspondence to Dr. Heunks: VU University Medical Center Amsterdam, Department of Intensive Care Medicine, Postbox 7057, 1007 MB Amsterdam, The Netherlands. L.Heunks@VUmc.nl. 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
Critical Care Medicine / Critical Care / Respiratory System
Critical Care Medicine   |   May 2018
Respiratory Muscle Effort during Expiration in Successful and Failed Weaning from Mechanical Ventilation
Anesthesiology Newly Published on May 15, 2018. doi:10.1097/ALN.0000000000002256
Anesthesiology Newly Published on May 15, 2018. doi:10.1097/ALN.0000000000002256
Abstract

Background: Respiratory muscle weakness in critically ill patients is associated with difficulty in weaning from mechanical ventilation. Previous studies have mainly focused on inspiratory muscle activity during weaning; expiratory muscle activity is less well understood. The current study describes expiratory muscle activity during weaning, including tonic diaphragm activity. The authors hypothesized that expiratory muscle effort is greater in patients who fail to wean compared to those who wean successfully.

Methods: Twenty adult patients receiving mechanical ventilation (more than 72 h) performed a spontaneous breathing trial. Tidal volume, transdiaphragmatic pressure, diaphragm electrical activity, and diaphragm neuromechanical efficiency were calculated on a breath-by-breath basis. Inspiratory (and expiratory) muscle efforts were calculated as the inspiratory esophageal (and expiratory gastric) pressure–time products, respectively.

Results: Nine patients failed weaning. The contribution of the expiratory muscles to total respiratory muscle effort increased in the “failure” group from 13 ± 9% at onset to 24 ± 10% at the end of the breathing trial (P = 0.047); there was no increase in the “success” group. Diaphragm electrical activity (expressed as the percentage of inspiratory peak) was low at end expiration (failure, 3 ± 2%; success, 4 ± 6%) and equal between groups during the entire expiratory phase (P = 0.407). Diaphragm neuromechanical efficiency was lower in the failure versus success groups (0.38 ± 0.16 vs. 0.71 ± 0.36 cm H2O/μV; P = 0.054).

Conclusions: Weaning failure (vs. success) is associated with increased effort of the expiratory muscles and impaired neuromechanical efficiency of the diaphragm but no difference in tonic activity of the diaphragm.