Title : Protective ventilation during cardiopulmonary bypass reduces postoperative pulmonary complications: A systematic review and meta analysis
Abstract:
Aim: To evaluate whether mechanical ventilation during cardiopulmonary bypass (CPB) reduces postoperative pulmonary complications (PPCs) in adult cardiac surgery patients.
Methods: We searched PubMed, Cochrane and Google Scholar for randomized controlled trials (RCTs) comparing ventilation during CPB versus no ventilation in adults. Paediatric studies and post-hoc analyses were excluded. Two reviewers independently screened studies and extracted data, a third reviewer resolved conflicts. The primary outcome was composite PPCs. Secondary outcomes included reintubation, mortality, inflammatory markers, and oxygenation. Risk of bias was assessed using Cochrane RoB 2.0 tool. Meta-analysis was conducted using Review Manager (RevMan) 5.4 with random-effects modelling and I² statistics for heterogeneity assessment.
Results: Six RCTs (3,373 patients) were included. Mean age ranged from 52-69 years, BMI 22.6-29.7 kg/m², CPB time 69-128 minutes, and cross-clamp time 35-83 minutes. Positive trials used tidal volumes of 3-4 mL/kg with PEEP 5-8 cmH?O; RCTs without PEEP showed no benefit. Two RCTs had low risk of bias, but four were analysed as moderate due to unclear outcome assessor blinding. Meta-analysis of PPCs (2,053 patients) showed significant benefit with ventilation (OR 0.74, 95% CI 0.60-0.92, P=0.006; I²=0%). Secondary outcomes analysed showed reduced reintubation (2.2% vs 5.1%), improved oxygenation (+60 mmHg), and lower incidence of pneumonia (3.6% vs 6.5%). Major limitations included unavailable full text for one trial, and heterogeneous outcome definitions with different primary endpoints.
Conclusion: Ventilation during CPB significantly reduces PPCs by 26%. Evidence supports protective ventilation (tidal volume 3-4 mL/kg with PEEP 5-8 cmH?O ); PEEP appears essential for achieving this benefit.
