Poorzand, Pouria

Background: The efficacy of different conventional ventilation during automated head-up (AHUP) CPR using active decompression and impedance threshold device with head and torso elevation is unknown. We sought to determine the central and peripheral hemodynamics while using the 10:1 versus the 30:2 positive pressure ventilation (PPV). Research Question: Does the PPV delivery method affect the hemodynamics during AHUP-CPR? Methods: Ventricular fibrillation was induced in anesthetized pigs (n=5), followed by AHUP-CPR initiation with positive pressure ventilations applied using an automated bag compressor to deliver 10ml/kg of tidal volume over 1 sec at a rate of 10 breaths/min. After 15 minutes of CPR using a 10:1 ratio, ventilation was changed to a 30:2 ratio for 2 minutes with 2 PPV delivered consecutively. Thereafter 10:1 ratio was resumed followed by another 2-minute round of 30:2 PPV mode. Intraventricular pressures and volumes using conductance catheters placed in the right ventricle (RV), along with other hemodynamic parameters were recorded continuously, during the 2-minute intervals between PPV delivery. A mixed-effects model was used to evaluate the effects of PPV mode on pressure-volume (PV) loop parameters while using a Spearman correlation to explore the relationship between PV loop indices. Results: There was no statistically significant difference between RV stroke volume (SV) with 10:1 versus 30:2 PPV mode (Table 1). Throughout 2 minutes, 30:2 ventilation mode resulted in a significantly higher end-tidal CO2 (ETCO2), and higher pressures with a higher pulmonary elastance (Ea) imposed on RV (p<0.05). Higher Ea was strongly correlated with lower SV and ETCO2 (Spearman's rho correlation confidence of -0.97 and -0.83, respectively). No significant differences were observed between the two ventilation modes in any other hemodynamic parameters, including intrathoracic, aortic and right atrial pressures, as well as coronary and cerebral perfusion pressures. Conclusion: No significant difference was found for right ventricular stroke volume when comparing one breath after 10 chest compressions to two breaths after 30 compressions during automated head-up CPR. Delivering two consecutive breaths after 30 continuous compressions led to an overall higher ETCO2, but it also imposed greater ventricular pressure and afterload, which were significantly correlated with reduced SV and ETCO2.

Background: Pre-clinical animal studies have demonstrated improved cerebral blood flow and neurological survival with Automated Head Up Position (AHUP) cardiopulmonary resuscitation (CPR) as compared to flat conventional (C) CPR. AHUP CPR consists of 1) automated head and thorax elevation 2) active compression decompression CPR and 3) an impedance threshold device. Subsequently, observational propensity-matched studies of out-of-hospital cardiac arrest (OHCA) patients demonstrated a time-dependent association between survival with intact neurological function (SNF) and application of AHUP CPR. However, comparison of AHUP CPR outcomes with contemporaneous C-CPR controls is lacking. Hypothesis: Use of AHUP CPR for OHCA by first responder agencies will demonstrate a higher incidence of SNF compared to C-CPR outcomes from a national registry Methods: Data from the previous 5 years (2020-2024) from an AHUP-CPR Registry comprised of OHCA patients routinely treated by first responders with AHUP CPR were compared with data from the Cardiac Arrest Registry to Enhance Survival (CARES). Patient demographics, arrest characteristics, ROSC, SHD, and SNF were recorded. SNF was defined as a Cerebral Performance Category 1 or 2 at hospital discharge. A two-sample test of proportions was used for outcome comparisons. Results: Nine AHUP registry sites (MN, FL, TN, IL, OK, VA, AL, IA, MI) were included. Summary 5-year demographics (Table 1) and clinical outcomes (Table 2) are presented. For 2020-2024 AHUP sites, the average time (mm:ss, SD) from 9-1-1 call to start of CPR was 9:09 (4:37) and time to start of AHUP CPR was 12:46 (5:57). The AHUP registry had a higher 5-yr incidence of SNF versus the CARES registry (difference 2.8%, 95% CI 1.8-3.8, p < 0.00001). This difference was consistent year over year (Figure 1). Secondary outcomes of sustained return of spontaneous circulation and survival to hospital discharge in the AHUP registry were also significantly higher than CARES registry data (Table 2). Conclusions: Over a 5-year period, an unadjusted analysis of aggregate data from two OHCA patient registries demonstrated that the incidence of survival with intact neurological function was higher in patients treated with AHUP CPR as part of first responder care versus patients treated with more conventional CPR methods.