Comparison of ventilation modes in non-traumatic out-of-hospital cardiac arrest: SYMEVECA phase 2.

Abstract

To compare clinical outcomes associated with different ventilation approaches during cardiac arrest. Pragmatic prospective quasi-experimental study in non-traumatic out-of-hospital cardiac arrest in adults attended by an emergency medical service between April-2021 and September-2024. Patients were classified in three groups according to the ventilation method during CPR: Chest Compression Synchronized Ventilation-CCSV (inspiratory time 205 ms), intermittent positive pressure ventilation-IPPV (tidal volume 7 ml/kg, rate 10-12 bpm) or manual resuscitator bag. Main outcome was survival at hospital discharge or 28 days with good neurological recovery (CPC 1-2). We also measured blood gas values 15 min after tracheal intubation or when spontaneous circulation was achieved. Of the 773 cardiac arrests recorded, 252 were excluded due to very early recovery (193), airway difficulty (54) or protocol violations (5). Patients were analyzed by groups: CCSV (100), IPPV (145) or resuscitator bag (276). In patients with a venous control sample, pH was 7.01 ± 0.15 in CCSV group, 7.00 ± 0.14 in IPPV and 6.96 ± 0.15 in the bag group (p = 0.02). The pCO₂ was 76.9 ± 31.8, 78.3 ± 25.4 and 84.7 ± 30.1 mmHg, respectively (p = 0.13). A spontaneous circulation was achieved in 61% with CCSV, 57.2% with IPPV and 49.3% with bag (p = 0.08). Survival with good neurological outcome was 16% in CCSV group, 12.4% in IPPV and 9.4% with bag (p = 0.19; p = 0.07 between CCSV and bag groups). Successful resuscitation may vary according to ventilation mode - the use of a mechanical ventilation and different modes such as CCSV requires further study.