Abstract Body: Background: Head Up Position (HUP) Cardiopulmonary Resuscitation (CPR) and Resuscitation Balloon Occlusion of the Aorta (REBOA) are emerging interventions for non-traumatic cardiac arrest. HUP-CPR includes automated head and thorax elevation, active compression decompression CPR, and an impedance threshold device. Pilot animal studies have shown a possible hemodynamic synergy with HUP-CPR +REBOA .

Hypothesis: HUP-CPR+REBOA will result in superior hemodynamics compared to Conventional (C) CPR+REBOA in the supine flat position, in a porcine model of prolonged cardiac arrest.

Methods: Farm pigs (n=10) were sedated, intubated, and anesthetized. Femoral central venous, arterial, and intracranial access was obtained and pressures were measured throughout the study. End tidal CO2 andcerebral oximetry were also monitored. Ventricular Fibrillation was induced and left untreated for 10 minutes and animals were randomized to either HUP-CPR+REBOA or C-CPR+REBOA. After 18 minutes of CPR, the REBOA was inflated in the Zone 1 region in both groups. After 26 minutes, epinephrine and amiodarone were given and defibrillation performed a minute later. An unpaired t-test was used for comparison between HUP-CPR and C-CPR groups. A paired t-test was used for comparison within groups, before and after REBOA.

Results: Hemodynamics are presented for each group in Table 1. Before REBOA inflation at 18 minutes, nearly all measurements were significantly higher in the HUP-CPR group than the C-CPR group. After REBOA inflation after 23 minutes of CPR, all hemodynamics were again significantly higher with HUP-CPR+REBOA versus C-CPR+REBOA. Mean arterial pressure (MAP) (mmHg, 42.6 ± 7 vs 51.6 ± 5, p < 0.01) and cerebralperfusion pressure (CerPP) (mmHg, 33.5 ± 9 vs 42.2 ± 7, p<0.01) were significantly higher after REBOA inflation within the HUP-CPR group (Figures 1,2). No significant changes were noted in the C-CPR groupbefore versus after REBOA inflation.

Conclusions: In this ongoing study, HUP-CPR resulted in superior hemodynamics versus C-CPR beforeREBOA inflation. After 18 minutes of CPR, MAP and CerPP were significantly higher after REBOA inflation in the HUP-CPR group. By contrast, no significant hemodynamic changes were observed in the C-CPR group after REBOA inflation. Further study is needed regarding the optimal timing of REBOA treatment to maximize hemodynamics during HUP-CPR. Overall, the HUP-CPR +REBOA combination is promising and should beconsidered for clinical study.