Time used for ventilation in two-rescuer CPR with a bag-valve-mask device during out-of-hospital cardiac arrest.

INTRODUCTION: Professional rescuers only deliver chest compressions 39% of the available time before intubation during out-of-hospital cardiac arrest. In manikin-studies lay rescuers need approximately 15s to deliver two ventilations. It is not known how much time professional rescuers use for two ventilations and we hypothesised that the time used for two ventilations with a bag-valve-mask device before tracheal intubation is longer than recommended and that the extended time contributes to the high no flow time.

METHODS: Quality of CPR was available for analysis in 628 cases of out-of-hospital cardiac arrest in the ambulance service in Oslo, Akershus, London, and Stockholm from 2002 to 2005. The 2000 Guidelines were used as the reference. Ventilations were registered from changes in transthoracic impedance as measured through the standard defibrillation pads. We included episodes only with CPR with a 15:2 pattern for at least 1 min and identified all pauses between chest compressions before intubation.

RESULTS: In the remaining 172 episodes we identified 3097 chest compression pauses. In 1587 (51%) of the pauses we identified two ventilations and a mean pause length for each episode was calculated. The median of these means was 5.5s (IQR; 4.5, 7). These pauses comprised a median 9% (IQR; 4%, 15%) of the time before intubation in these episodes. In 892 (29%) of the pauses we identified a different number of ventilations, or other interventions in addition to ventilation. In the remaining 618 pauses (20%) no ventilations were registered.

CONCLUSIONS: Professional rescuers delivered two bag-valve-mask ventilations within the 5-6s as indicated in the 2000 Guidelines, slightly longer than the 3-4s recommended in the 2005 Guidelines. However, only half the pauses were used for two ventilations, and the total time for two ventilations accounted for only 27% of the time without chest compressions. Excessive time for ventilation cannot explain the high no-flow time during CPR by professional rescuers before intubation.