Abstract Body: Background: Elevation of the head and thorax (HUP) in combination with active compression decompression (ACD) cardiopulmonary resuscitation (CPR) and an impedance threshold device (ITD) is starting to be used clinically by first responders. Extracorporeal membrane oxygenation in cardiac arrest (ECPR) for refractory cardiac arrest is also increasingly used and evolving. The potential benefit of ACD+ITD HUP CPR with ECPR is unclear.
Aim: Demonstrate superior incidence of survival with ACD+ITD HUP CPR versus ACD+ITD CPR flat in an animal model that includes salvage with ECPR.
Methods: Female and male Yorkshire-hybrid swine (~40 kg) were sedated and anesthetized. After intubation, bilateral percutaneous venous and arterial access were obtained. High fidelity micromanometer pressure transducers were used to measure arterial and venous pressures. Regional cerebral tissue oxygenation (rSO2) was also continuously monitored. Ventricular fibrillation was induced and left untreated for 15 minutes. During this time, animals were randomized to 1) HUP CPR or 2) flat CPR, and ACD+ITD CPR in both groups was then performed for 45 minutes. At 44 minutes, epinephrine and amiodarone were given and defibrillation attempted up to 3 times. If return of spontaneous circulation (ROSC) was not obtained, ECPR was then performed and continued for up to 6 hours. Neurological assessment was performed at 24 hours post arrest by a veterinarian blinded to the intervention. A Fisher’s exact test was used to compare outcomes between groups and an unpaired t-test for continuous data.
Results: In this ongoing study (n=17), 8 animals were randomized to HUP and 9 to flat. After 44 minutes of CPR, mean ± SD rSO2 (%) was 63 ± 7.7 for the HUP group and 54.7 ± 6.6 for the flat group (p = 0.04). ROSC was achieved in 4/8 (50%) in the HUP group and 4/9 (44%) in the flat group (p = 1.0). ECPR was performed in 3/8 (37.5%) in the HUP group and 5/9 (56%) in the flat group (p = 0.64). Most animals (7/8, 88%) had ECPR performed successfully. ROSC was not obtained and ECPR deemed futile in one HUP animal. At 24 hours, 3/8 (37.5%) of the HUP animals and 0/9 (0%) of the flat animals survived (p= 0.08). One HUP animal (12.5%) survived without any neurologic deficit. None of the animals that required ECPR survived to 24 hours.
Conclusions: In this severe model of cardiac arrest, a small number of animals survived, all of them receiving ACD+ITD HUP CPR and did not require ECPR.