Investigating the Association of Positive End-Expiratory Pressure (PEEP) with Postoperative Bleeding in Emergency Off-Pump Coronary ArteryBypass Grafting (CABG): A Randomized Controlled Trial

Introduction: Coronary artery disease (CAD) is a leading cause of cardiovascular mortality, with off-pump coronary artery bypass grafting (CABG) being a common surgical intervention. This study investigates the impact of increasing positive end-expiratory pressure (PEEP) to 10 cm HⁿO on postoperative bleeding in emergency off-pump CABG. Methods: This single-blinded randomized controlled trial was conducted at Imam Reza Hospital in 2023. A total of 122 patients were enrolled, with 59 in the intervention group and 63 in the control group. Patients in the intervention group received mechanical ventilation with PEEP set at 10 cm HⁿO in the ICU postoperatively, while the control group maintained a standard PEEP of 5 cm HⁿO. Data on blood loss, hemoglobin levels, and transfusion requirements were meticulously collected. Results: Baseline characteristics were similar between groups. No significant differences were observed in blood loss or transfusion requirements at 12, 24, or 48 hours postoperatively. Coagulation tests (PT, PTT, INR, and platelet count) were also comparable between groups during the 72-hour follow-up. Hemoglobin was significantly higher in the intervention group at 72 hours (P = 0.02). Reoperation rates and ventilation duration were lower in the intervention group, though differences were not statistically significant. Conclusions: Increasing PEEP to 10 cm HⁿO did not significantly reduce postoperative bleeding but was associated with higher hemoglobin levels at 72 hours. Further research is warranted to confirm these findings and explore the potential long-term benefits of increased PEEP in offpump CABG recovery. Iranian Registry of Clinical Trials (IRCT20231021059798N1).