Background: The reduction in functional residual capacity (FRC) is a significant pathological factor in the development of postoperative pulmonary complications. Appropriate positive end-expiratory pressure (PEEP) is critical to preserve FRC during mechanical ventilation. Our previous study suggests that using driving pressure-guided PEEP can reduce postoperative pulmonary complications. In this study, we hypothesize that individualized PEEP can increase immediate postoperative FRC and improve lung ventilation.
Methods: This single-centered, randomized controlled trial included a total of 91 patients scheduled for laparoscopic surgery for colorectal carcinoma. Patients were randomly assigned to receive individualized PEEP guided by minimum driving pressure or a fixed PEEP of six cmH<inf>2</inf>O. The primary outcome was postoperative FRC. Secondary outcomes included the incidence of postoperative pulmonary complications, postoperative Oxygenation Index, alveolar-arterial oxygen tension difference (P<inf>A-a</inf>O<inf>2</inf>), intrapulmonary shunt (Q<inf>S</inf>/Q<inf>T</inf>), and Respiratory Index, as well as lung ventilation measured by electrical impedance tomography.
Results: The median value of PEEP in the individualized group was 14 cmH<inf>2</inf>O, with an interquartile range of 12-14 cmH<inf>2</inf>O. The postoperative FRC was significantly higher in the individualized PEEP group than that in the PEEP six cmH<inf>2</inf>O group (32.8 [12.8] vs. 25.0 [12.6] mL/kg, P=0.004). Patients receiving driving pressure-guided PEEP also had significantly higher Oxygenation Index, better ventilation distribution, and lower PA-aO<inf>2</inf>, Q<inf>S</inf>/Q<inf>T</inf>, and Respiratory Index.
Conclusions: Driving pressure-guided PEEP can preserve postoperative FRC and provide better ventilation and oxygenation for patients undergoing laparoscopic colorectal surgery.