Individualised positive end-expiratory pressure in abdominal surgery: a systematic review and meta-analysis

Abstract

Background: Individualised positive end-expiratory pressure (PEEP) may optimise pulmonary compliance, thereby potentially mitigating lung injury. This meta-analysis aimed to determine the impact of individualised PEEP vs fixed PEEP during abdominal surgery on postoperative pulmonary outcomes. Methods: Medical databases (PubMed, Embase, Web of Science, ScienceDirect, Google Scholar, and the China National Knowledge Infrastructure) were searched for RCTs comparing fixed vs individualised PEEP. The composite primary outcome of pulmonary complications comprised hypoxaemia, atelectasis, pneumonia, and acute respiratory distress syndrome. Secondary outcomes included oxygenation (PaO2/FiO2) and systemic inflammatory markers (interleukin-6 [IL-6] and club cell protein-16 [CC16]). We calculated risk ratios (RRs) and mean differences (MDs) with 95% confidence interval (CI) using DerSimonian and Laird random effects models. Cochrane risk-of-bias tool was applied. Results: Ten RCTs (n=1117 patients) met the criteria for inclusion, with six reporting the primary endpoint. Individualised PEEP reduced the incidence of overall pulmonary complications (141/412 [34.2%]) compared with 183/415 (44.1%) receiving fixed PEEP (RR 0.69 [95% CI: 0.51–0.93]; P=0.016; I2=43%). Risk-of-bias analysis did not alter these findings. Individualised PEEP reduced postoperative hypoxaemia (74/392 [18.9%]) compared with 110/395 (27.8%) participants receiving fixed PEEP (RR 0.68 [0.52–0.88]; P=0.003; I2=0%) but not postoperative atelectasis (RR 0.93 [0.81–1.07]; P=0.297; I2=0%). Individualised PEEP resulted in higher PaO2/FiO2 (MD 20.8 mm Hg [4.6–36.9]; P=0.012; I2=80%) and reduced systemic inflammation (lower plasma IL-6 [MD –6.8 pg ml−1; –11.9 to –1.7]; P=0.009; I2=6%; and CC16 levels [MD –6.2 ng ml−1; –8.8 to –3.5]; P<0.001; I2=0%) at the end of surgery. Conclusions: Individualised PEEP may reduce pulmonary complications, improve oxygenation, and reduce systemic inflammation after abdominal surgery. Clinical trial registration: CRD42021277973.