Incremental balloon deflation following complete reboa results in steep inflection of flow and rapid reperfusion in a large animal model of hemorrhagic shock.

Introduction: To avoid potential cardiovascular collapse after Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA), current guidelines recommend methodically deflating the balloon over 5 minutes to gradually reperfuse distal tissue beds. However, anecdotal evidence suggests that this approach may still result in unpredictable aortic flow rates and hemodynamic instability. We sought to characterize aortic flow dynamics following REBOA as the balloon is deflated in accordance with current practice guidelines. Methods: Eight Yorkshire-cross swine were splenectomized, instrumented, and subjected to rapid 25% total blood volume hemorrhage. After 30 minutes of shock, animals received 60 minutes of zone 1 REBOA with a low-profile REBOA catheter. During subsequent resuscitation with shed blood, the aortic occlusion balloon was gradually deflated in stepwise fashion at the rate of 0.5 mL every 30 seconds until completely deflated. Aortic flow rate and proximal mean arterial pressure (MAP) were measured continuously over the period of balloon deflation. Results: Graded balloon deflation resulted in variable initial return of aortic flow (median 78 seconds, IQR 68-105sec). A rapid increase in aortic flow during a single balloon deflation step was observed in all animals (Median 819 mL/min IQR 664-1241mL/min) and corresponded with an immediate decrease in proximal MAP (Median 30 mmHg IQR 14.5-37mmHg). Total balloon volume and time to return of flow demonstrated no correlation (r2=0.016). Conclusion: This study is the first to characterize aortic flow during balloon deflation following REBOA. A steep inflection point occurs during balloon deflation that results in an abrupt increase in aortic flow and a concomitant decrease in MAP. Furthermore, the onset of distal aortic flow was inconsistent across study animals and did not correlate with initial balloon volume or relative deflation volume. Future studies to define the factors that impact aortic flow during balloon deflation are needed to facilitate controlled reperfusion following REBOA. Level of Evidence: Level V (C) 2017 Lippincott Williams & Wilkins, Inc.

from Emergency Medicine via xlomafota13 on Inoreader http://ift.tt/2onC0YQ