Abstract Body: Background: Addition of resuscitative endovascular balloon occlusion of the aorta (REBOA) to automated head-up position (AHUP) cardiopulmonary resuscitation (CPR), the combination of active compression decompression CPR, an impedance threshold device, and controlled gradual elevation of the head and thorax, increases cerebral perfusion pressure. Optimal management of REBOA deflation after prolonged AHUP-CPR and ROSC is unknown.

Hypothesis: We hypothesized that partial deflation of REBOA, rather than full deflation after ROSC, would result in better hemodynamic parameters.

Aims: To compare hemodynamic parameters 1 minute before and 1 minute after complete (100%) versus partial (50%) REBOA deflation after prolonged AHUP-CPR and ROSC.

Methods: Yorkshire pigs weighing ∼40 kg were anesthetized and ventilated. After 10 minutes of untreated ventricular fibrillation, AHUP-CPR was started and continued for a median time of 44 minutes. After ROSC, REBOA deflation was initiated in two ways: complete (100%) or partial (50%) deflation over 5 seconds. The following hemodynamic parameters were measured 1 minute before and 1 minute after deflation: mean aortic pressure (MAP), cerebral perfusion pressure (CerPP), and coronary perfusion pressure (CorPP). Data, in mmHg, are presented as mean ± SD, and compared using a paired t-test.

Results: 13 pigs were included, with 8 pigs in the 100% deflation group and 5 in the 50% deflation group. After ROSC in the 100% deflation group, MAP was 81.5±36.0 before deflation vs. 43.0±14.4 after (p=0.01), whereas in the 50% deflation group, MAP was 90.5±33.0 vs. 83.4±33.3 (p=0.02). CerPP was 72.3±34.4 before deflation vs. 35.9±14.6 (p=0.01) in the 100% deflation group, and 84.6±31.2 vs. 77.6±31.8 (p=0.02) with 50% deflation. Similarly, CorPP was 74.1±37.3 before deflation vs. 36.1±15.8 (p=0.01) after in the 100% deflation group, and 83.0±32.7 vs. 76.1±33.0 (p=0.02) in the 50% deflation group. The differences from before to after deflation were markedly less in the 50% deflation group versus the 100% deflation group: MAP (7.0±4.3 vs. 38.5±25.7, p=0.02), CerPP (7.1±4.4 vs. 36.3±24.4, p=0.02), and CorPP (6.0±4.2 vs. 39.8±25.2, p=0.02), respectively.

Conclusion: In this porcine model of prolonged cardiac arrest, partial deflation of the REBOA balloon post ROSC resulted in strikingly higher hemodynamics compared with complete deflation. These findings highlight the need to develop a post-ROSC REBOA deflation strategy when used during AHUP-CPR.