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

Abstract

Aim: To compare clinical outcomes associated with different ventilation approaches during cardiac arrest.

Methods: 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.

Results: 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).

Conclusion: Successful resuscitation may vary according to ventilation mode - the use of a mechanical ventilation and different modes such as CCSV requires further study.

Keywords: Blood Gas Analysis; Cardiac arrest; Emergency Medical Services; Mechanical ventilation.