The effect of ventilation rate on outcome in adults receiving cardiopulmonary resuscitation.

Abstract

To investigate whether a ventilation rate ≤10 breaths min^-1 in adult cardiac arrest patients treated with tracheal intubation and chest compressions in a prehospital setting is associated with improved Return of Spontaneous Circulation (ROSC), survival to hospital discharge and one-year survival with favourable neurological outcome, compared to a ventilation rate >10 breaths min^-1. In this retrospective study, prospectively acquired data were analysed. Ventilation rates were measured with end-tidal CO₂ and ventilation pressures. Analyses were corrected for age, sex, compression rate, compression depth, initial heart rhythm and cause of cardiac arrest. 337 of 652 patients met the inclusion criteria. Hyperventilation was common, with 85% of the patients ventilated >10 breaths min^-1. The mean ventilation rate was 15.3 breaths min^-1. The corrected odds ratio (OR) of ventilating >10 breaths min^-1 for achieving ROSC was 0.91 (95% CI: 0.49 - 1.71, p = 0.78), the uncorrected OR of ventilating >10 breaths min^-1 for survival to hospital discharge was 0.91 (95% CI: 0.30 - 2.77, p = 0.78), and the uncorrected OR of ventilating >10 breaths min¹ for one-year survival with a favourable neurological outcome was 0.59 (95% CI: 0.19 - 1.87, p = 0.32). A logistic regression with continuous ventilation rate showed no significant relation with ROSC, and a ROC curve for ROSC showed a poor predictive performance (AUC: 0.52, 95% CI: 0.46 - 0.58), suggesting no other adequate cut-off value for ventilation rate. A ventilation rate ≤10 breaths min^-1 was not associated with significantly improved outcomes compared to a ventilation rate >10 breaths min^-1. No other adequate cut-off value could be proposed.