Impact of 'synchronous' and 'asynchronous' CPR modality on quality bundles and outcome in out-of-hospital cardiac arrest patients

During cardiopulmonary resuscitation (CPR), the need to interrupt chest compressions to provide synchronous ventilations prevents blood flow continuity, reducing the possibility to ensure high-quality CPR bundles of care and, thus, having a potentially negative impact on perfusion and patient outcome. Contemporaneous asynchronous chest compressions and ventilations may avoid these potentially negative effects. Only a few studies measured the CPR quality metrics during synchronous and asynchronous CPR modality and its relation to patient outcome. A prospective observational study was conducted on 285 consecutive adult patients with out-of-hospital cardiac arrest treated by EMS teams over a 30-month period. Ventilation rate, chest compression fraction (i.e. cardiac arrest time spent delivering uninterrupted chest compressions compared to total cardiac arrest time) and chest compression rate per minute were collected in real time by defibrillators and analysed through a dedicated software (electrical cardiac activity through the ECG, chest compression and ventilations through the transthoracic impedance) during synchronous and asynchronous CPR modalities. During asynchronous CPR modality, higher ventilation rate and chest compression fraction (p  < 0.001), and lower chest compression rate per minute (p < 0.001) were ensured, being all cited metrics more adherent to the high-quality CPR bundles. Ventilation rate provided during the whole CPR was an independent predictor for a good neurological outcome (OR 3.795, p = 0.005). Asynchronous chest compression and ventilation ensured the most adequate chest compression fraction, uninterrupted chest compression rate and ventilation rate.