The Effect of Open Lung Ventilation on Respiratory Mechanics, Postoperative Organ Function, and Inflammatory Mediators in Coronary Artery Bypass Surgery

Abstract

Background & Objective: The present study aimed to assess the supportive role of open lung ventilation on respiratory mechanics, the rate of oxygenation, inflammatory biomarkers, and probable liver or renal injuries following coronary artery bypass grafting surgery. Materials & Methods: This randomized double-blinded clinical trial study was conducted on 64 candidates for coronary artery bypass surgery using a cardiopulmonary pump. The patients were randomly categorized into the Positive end-expiratory pressure (PEEP) group (n = 32) or Zero End Expiratory Pressure (ZEEP) group (n = 32). Results: Interleukin-6 levels were similar between the PEEP and ZEEP groups before surgery (p = 0.18) and were significantly higher in the ZEEP group after pump insertion (p = 0.005). On the contrary, the levels of Interleukin-6 were significantly higher in the PEEP group after extubation (p = 0.001). The Between-group analysis also showed a significant difference between the levels of interleukin-6 in the ZEEP and PEEP groups, representing a greater increase in the PEEP group (p < 0.001). There was no difference in certain hemodynamic parameters, including heart rate, mean blood pressure, mean CO2 pressure (PCO2), mean concentration of HCO3, and base excess. The mean arterial O2 saturation was higher overall in the PEEP group compared to the ZEEP group. The mean PaO2/FiO2 was significantly higher in the PEEP than in the ZEEP group (p < 0.001). Conclusion: Supportive ventilation technique leads to better oxygenation and better lung expansion, as well as lowering inflammatory biomarkers, after coronary artery bypass surgery.