Ventilatory improvement with mechanical ventilator versus bag in non-traumatic out-of-hospital cardiac arrest: SYMEVECA study, phase 1.

Abstract

To analyze differences in ventilatory parameters and outcome with different ventilatory methods during CPR. Pragmatic prospective quasi-experimental study in out-of-hospital urban environment. Patients over 18 years of age in non-traumatic cardiac arrest, attended by an emergency medical service between April 2021 and September 2022, were included. Two groups were compared according to the ventilatory method: mechanical ventilator (IPPV, tidal volume 7 ml/kg, frequency 10-12 bpm) or manual resuscitator bag. The main variables of interest are those of gasometry performed 15 minutes after intubation or when spontaneous circulation is recovered and final outcome. Patients were followed up to hospital discharge. Of the 359 patients attended, 150 were included (71 in IPPV and 79 with a bag). In patients with arterial blood gases, pCO₂ was 67.8 ± 21.1 in the IPPV group vs 95.9 ± 39.0 mmHg in the bag group (p = 0.006) and pH was 7.00 ± 0.18 vs 6.92 ± 0.18 (p = 0.18). With a venous sample, the pCO₂ was 68.1 ± 18.9 vs 89.5 ± 26.5 mmHg (p < 0.001) and the pH was 7.03 ± 0.15 vs 6.94 ± 0.17 (p = 0.005), respectively. Survival with CPC 1-2 to hospital discharge was 15.6% with IPPV and 11.3% with bag (p = 0.44). The use of a mechanical ventilator in IPPV was associated with a better ventilatory status during CPR compared to the use of the bag, without conclusive data regarding its clinical repercussion with the sample collected.