Bag Size for Manual Ventilation During Cardiopulmonary Resuscitation in Adult Cardiac Arrest: A Systematic Review

Background Smaller-capacity self-inflating bags have been proposed to limit delivered tidal volume during adult cardiopulmonary resuscitation (CPR). This review evaluates whether using smaller-capacity self-inflating bags, compared with standard-size adult bags, for manual ventilation during CPR affects patient and ventilation outcomes. Methods We conducted a systematic review using the ILCOR Continuous Evidence Evaluation approach, searching MEDLINE, Embase, Web of Science, and CENTRAL from inception to May 7, 2026 (PROSPERO CRD420251266387). Eligible studies included randomised and non-randomised designs in humans and simulation. Critical outcomes were survival to discharge or 30 days with and without favourable neurological outcome. Important outcomes included survived event, return of spontaneous circulation (ROSC), tidal volume, ventilation rate, and adverse events. Certainty of evidence was assessed using GRADE. Results No randomised trials were identified. Evidence comprised one before-and-after observational study (n=1,994 out-of-hospital cardiac arrest patients with advanced airways) and two cross-over simulation studies. The observational study compared periods using smaller ventilation bags (450–700 mL) with standard adult bags (1000–1685 mL). Compared with the standard-bag period, the smaller-bag period was associated with lower survival with favourable neurological outcome (AOR 0.65, 95% CI 0.43–0.99) and lower event survival (adjusted odds ratio [AOR] 0.73, 95% CI 0.60–0.90). Survival to discharge and ROSC did not differ significantly. Simulation studies demonstrated inconsistent effects of bag size on guideline-consistent tidal volume delivery. The certainty of evidence was very low for all outcomes. Conclusions Although evidence is very limited and of very-low certainty, smaller bags may influence delivered tidal volume and worsen patient outcomes. Routine substitution of standard adult bags with small bags during CPR is not supported.