Intraoperative Mechanical Ventilation and Postoperative Pulmonary Complications after Cardiac Surgery
Michael R. Mathis, M.D.; Neal M. Duggal, M.D.; Donald S. Likosky, Ph.D.; Jonathan W. Haft, M.D.; Nicholas J. Douville, M.D., Ph.D.; et al Michelle T. Vaughn, M.P.H.; Michael D. Maile, M.D., M.S.; Randal S. Blank, M.D., Ph.D.; Douglas A. Colquhoun, M.B., Ch.B., M.Sc., M.P.H.; Raymond J. Strobel, M.D., M.S.; Allison M. Janda, M.D.; Min Zhang, Ph.D.; Sachin Kheterpal, M.D., M.B.A.; Milo C. Engoren, M.D.
 Author Notes
From the Departments of Anesthesiology (M.R.M., N.M.D., N.J.D., M.T.V., M.D.M., D.A.C., A.M.J., S.K., M.C.E.) and Cardiac Surgery (D.S.L., J.W.H., R.J.S.), University of Michigan Medical School, and Department of Biostatistics, University of Michigan (M.Z.), Ann Arbor, Michigan; Department of Anesthesiology, University of Virginia School of Medicine, Charlottesville, Virginia (R.S.B.).
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 October 8, 2018. Accepted for publication July 2, 2019.
Correspondence: Address correspondence to Dr. Mathis: Department of Anesthesiology, University of Michigan, 1H247 UH, SPC 5048, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109-5048. mathism@med.umich.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.
Anesthesiology Newly Published on August 8, 2019. doi:10.1097/ALN.0000000000002909
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Abstract
Editor’s Perspective:

What We Already Know about This Topic:

Modern ventilation approaches use a bundle of lower tidal volumes, lower driving pressures, and positive end-expiratory pressure

The contributions of each component to reducing postoperative pulmonary complications in an adult cardiac surgical population is not known

What This Article Tells Us That Is New:

In this retrospective analysis, the intraoperative ventilation bundle was associated with a lower rate of postoperative pulmonary complications

Lower modified driving pressure was independently associated with fewer pulmonary complications

Background: Compared with historic ventilation strategies, modern lung-protective ventilation includes lower tidal volumes (VT), lower driving pressures, and application of positive end-expiratory pressure (PEEP). The contributions of each component to an overall intraoperative protective ventilation strategy aimed at reducing postoperative pulmonary complications have neither been adequately resolved, nor comprehensively evaluated within an adult cardiac surgical population. The authors hypothesized that a bundled intraoperative protective ventilation strategy was independently associated with decreased odds of pulmonary complications after cardiac surgery.

Methods: In this observational cohort study, the authors reviewed nonemergent cardiac surgical procedures using cardiopulmonary bypass at a tertiary care academic medical center from 2006 to 2017. The authors tested associations between bundled or component intraoperative protective ventilation strategies (VT below 8 ml/kg ideal body weight, modified driving pressure [peak inspiratory pressure − PEEP] below 16 cm H2O, and PEEP greater than or equal to 5 cm H2O) and postoperative outcomes, adjusting for previously identified risk factors. The primary outcome was a composite pulmonary complication; secondary outcomes included individual pulmonary complications, postoperative mortality, as well as durations of mechanical ventilation, intensive care unit stay, and hospital stay.

Results: Among 4,694 cases reviewed, 513 (10.9%) experienced pulmonary complications. After adjustment, an intraoperative lung-protective ventilation bundle was associated with decreased pulmonary complications (adjusted odds ratio, 0.56; 95% CI, 0.42–0.75). Via a sensitivity analysis, modified driving pressure below 16 cm H2O was independently associated with decreased pulmonary complications (adjusted odds ratio, 0.51; 95% CI, 0.39–0.66), but VT below 8 ml/kg and PEEP greater than or equal to 5 cm H2O were not.

Conclusions: The authors identified an intraoperative lung-protective ventilation bundle as independently associated with pulmonary complications after cardiac surgery. The findings offer insight into components of protective ventilation associated with adverse outcomes and may serve as targets for future prospective interventional studies investigating the impact of specific protective ventilation strategies on postoperative outcomes after cardiac surgery.