Objective:

To evaluate the effects of higher vs. lower fixed PEEP strategies on intraoperative hypotension and postoperative pulmonary complications specifically in thoracic surgery patients.

Key Findings:

• Higher PEEP significantly increased the risk of intraoperative hypotension (RR: 2.16, 95% CI: 1.29–3.63, p = 0.003).
• Higher PEEP did not significantly reduce the risk of postoperative pulmonary complications (RR: 0.95, 95% CI: 0.88–1.02, p = 0.179).
• New-onset arrhythmia was more frequent with higher PEEP (RR: 2.56, 95% CI: 1.76–3.71).
• Rescue hypoxaemia interventions were less frequent with higher PEEP (RR: 0.37, 95% CI: 0.25–0.56).
• Intraoperative PaO2 was directionally higher with higher PEEP but statistically inconclusive due to heterogeneity.

Interpretation:

Higher fixed PEEP during OLV increases the risk of intraoperative hypotension without providing measurable benefits in reducing postoperative pulmonary complications.

Limitations:

• Moderate certainty of evidence due to heterogeneity in studies.
• Limited number of studies included in the analysis, which may affect the robustness of the findings.

Conclusion:

Routine application of higher fixed PEEP during OLV should be approached with caution; future research should actively explore individualized PEEP titration strategies.