Intraoperative Mechanical Ventilation and Postoperative Pulmonary Complications after Cardiac Surgery

Abstract

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New 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 reduced 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.

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“…1,2 PPCs not only increase the postoperative mortality of patients but also prolong the length of hospital stay and medical costs for patients. 3 For decades, the development of cardiopulmonary bypass and surgical technologies for open-heart surgery has continued to benefit patients with cardiovascular disease, but surgical procedures, extracorporeal circulation, protamine application during surgery, mechanical ventilation, lungs undergoing ischemia-reperfusion, and systemic inflammatory reactions lead to varying degrees of pulmonary complications in patients after cardiac surgery. Faced with pulmonary complications after cardiac surgery, the current prevention and treatment methods have limited effects.…”

Driving pressure guided ventilation

“…V T , Pplat and PEEP were not related to patient outcomes, or only related when they influenced the driving pressure. Several retrospective and prospective studies confirmed the importance of driving pressure in ARDS patients [18,19] and surgical patients [12,[20][21][22].…”

“…In a cohort study of cardiac surgery patients published in 2019 (n = 4,694), a lung-protective ventilation bundle was applied to 1,913 patients (40.8%) [20]. Postoperative pulmonary complications were reduced by its application (13.9% vs. 6.6%, OR 0.56, 95% CI 0.42 to 0.75).…”

“…This protective ventilation bundle was comprised of V T < 8 ml/kg ideal body weight, modified driving pressure [peak inspiratory pressure -PEEP] < 16 cmH 2 O, and PEEP ≥ 5 cmH 2 O. Of these components, modified driving pressure < 16 cmH 2 O was independently associated with decreased pulmonary complications (OR 0.51, 95% CI, 0.39 to 0.66), but V T < 8 ml/kg and PEEP ≥ 5 cmH 2 O were not [20].…”

“…These retrospective studies clearly show that high driving pressure is the best indicator of poor prognosis, but do not confirm that active control of driving pressure reduces complications or improves outcomes. The previous cohort study conducted in cardiac surgery patients did not give a detailed account of the technique to reduce driving pressure in their protective ventilation bundle [20].…”