ESICM LIVES 2019 : Berlin, Germany. 28 September - 2 October 2019

INTRODUCTION. Capnographic CO2 oscillations have been described during Cardiopulmonary Resuscitation (CPR). The Airway Opening Index (AOI) has been recently proposed to quantify the CO2 oscillations at capnography during chest compressions (CCs).(1) It has been proposed that a low oscillating EtCO2 during CCs is a result of airway collapse, which obstructs the expiratory airflow. The aim of this study is to assess the change of AOI over time during 18 minutes of CPR in a porcine model of cardiac arrest (CA). We will assess the relationship between manual and mechanical CCs, the compliance of the respiratory system (Cpl,rs) and the duration of CPR with the AOI. METHODS. Adult male swine were randomized to 18 min of CPR with mechanical (LUCAS® 3.0) or manual CCs after 2 minutes of CA. Mechanical ventilation was provided with tidal volume 500 ml, 10 bpm, FiO2 1.0, ZEEP). Hemodynamic parameters, EKG, SpO2, EtCO2were continuously recorded. Cpl,rs was assessed after return of spontaneous circulation (ROSC). The AOI was computed as ΔCO2/CO2max and the values were averaged on the number of CCs (n=6) during each minute of CPR. RESULTS. The mean AOI was significantly higher in the manual CCs group compared to the mechanical group(58±5% vs 24±3%, p< 0.0001 Fig 1a). The AOI was higher in the manual CCs group compared to the mechanical group throughout the time of CPR. No decrease of AOI has been identified over time within each group (Fig 1b). The mean value of AOI measured at the end of CPR (minute 18) showed a good correlation with Cpl,rs (r=0.749, p=0.0006, Fig 1c). CONCLUSION. In a randomized porcine model of CA, AOI was significantly higher in the manual compared to the mechanical CCs group during the all 18 minutes of CPR. Cpl,rs was strongly associated with the AOI at the end of CPR.