The effect of intraoperative lung protective ventilation vs conventional ventilation, on postoperative pulmonary complications after cardiopulmonary bypass

Introduction: This study aimed to evaluate the effects of high positive-end expiratory pressure (PEEP) and low tidal volume (TV) and recruitment maneuver, on postoperative pulmonary complications (PPCs) after coronary artery bypass grafting (CABG) surgery.

Methods: This study is a randomized double blind clinical trial on 64 patients who were undergoing CABG surgery, and were randomly divided into two groups of conventional ventilation (C-Vent) with TV of 9 mL/kg and PEEP=0 cm H2O, and lung protective ventilation (P-Vent), with 6 mL/kg TV and PEEP=10 cm H2O with recruitment maneuver every 30 minutes. Measures of PPCs and modified clinical pulmonary infection score (mCPIS), were assessed for the first 24 hours of postoperative time in order to evaluate the pulmonary complications.

Results: P-Vent with 31 patients and C-Vent with 30 patients, participated in the stage of data analysis. Demographic, and preoperative laboratory results showed no significant difference between two groups. During surgery, cardiovascular complications were higher in P-Vent group (P = 0.61) but pulmonary complications were higher in C-Vent group (P = 0.26). Extubation time was not significantly different between two groups, and also components of arterial blood gases (ABG) of 24 hours after surgery showed no significant difference between the two groups. Pathologic changes in the chest X-ray (CXR) of 24 hours after surgery, were lower in P-Vent group, but the difference was not significant (P = 0.22). The PPC criteria was less positive in P-Vent (2 patients) vs 9 patients in C-Vent group (P = 0.02) and mCPIS score was significantly lower in P-Vent group (1.2 ± 1.4) than C-Vent group (2 ± 1.6) (P = 0.048).

Conclusion: Lung protective strategy during and after cardiac surgery, reduces the postoperative mCPIS in patients undergoing open heart surgery for CABG.