2019 Basic Science Presentations

Dominic M Forte, Woo S Do, MD, Jessica B Weiss, MD, Rowan R Sheldon, MD, Matthew J Eckert, MD, Matthew J Martin; Madigan Army Medical Center

Objectives: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is effective as a temporizing measure in non-compressible truncal hemorrhage (NCTH). However, use for longer than 60min causes lethal reperfusion injury. Partial REBOA (pREBOA) has been offered as a possible solution. We aim to demonstrate increased survivability with pREBOA when compared to full REBOA in porcine hemorrhagic shock model.

Methods: 10 Yorkshire swine (sus scrofa) underwent 20% blood volume hemorrhage followed by placement of the ER REBOA catheter (Prytime Medical, Boerne, TX) in zone 1 (intrathoracic). Swine were then randomized to liver injury or vascular injury (combined iliac vessel injury). The ER REBOA was inflated for 60min, then deflated. The experiment concluded at 2hrs or if MAPS were sustained < 20mmHg. A second group of 10 swine underwent similar hemorrhage. A novel pREBOA catheter (Prytime Medical, Boerne, TX) was placed and the swine were randomized to injury type. The pREBOA was inflated fully for 10min, then partially inflated to allow a flow of .5L/min for two hours. This flow goal was arrived at from prior experiments to balance the risk of hemorrhage and the risk of reperfusion injury. Hemodynamics were continuously monitored and lab values were assessed every 30 minutes.

Results: 2/10 swine survived to 2hr in the full REBOA control group (Vascular 1/5, Liver injury 1/5). Average lactate at 2hr was 16.9mg/dL (SD 3.9). 7/10 swine survived to 2hr in the pREBOA (Vascular 4/5, Liver Injury 3/5). All deaths in the pREBOA group were secondary to fatal arrhythmia. In surviving pREBOA animals, mean lactate at 2hr was 12.7 mg/dL (SD 2.5 mg/dL). Lactate significantly differed from the full REBOA controls at 60 and 90min timepoints. In comparing the pREBOA animals that lived to those that died, there was no difference between the distal mean arterial pressure (MAP), proximal MAP, heart rate, lactate, urea, creatinine, pH, and potassium when pooled by injury type or survival. However, there was a difference in Calcium in these animals at 30min post-injury (8.6 mg/dL and 7.2 mg/dL, p= .02). There was a correlation between death, low calcium, and high potassium.

Conclusion: Prolonged partial REBOA at a moderate distal flow of .5L/min is a potentially viable temporizing measure in NCTH when surgical treatment must be delayed which gives improved survival when compared to use of full REBOA. Calcium administration may be a means of addressing the identified complication of fatal arrhythmia.