Automated variable aortic control versus complete aortic occlusion in a swine model of hemorrhage

Abstract

Background Future endovascular hemorrhage control devices will require features that mitigate the adverse effects of vessel occlusion. Permissive regional hypoperfusion (PRH) with variable aortic control (VAC) is a novel strategy to minimize hemorrhage and reduce the ischemic burden of complete aortic occlusion (AO). The objective of this study was to compare PRH with VAC to AO in a lethal model of hemorrhage. Methods Twenty-five swine underwent cannulation of the supraceliac aorta, with diversion of aortic flow through an automated extracorporeal circuit. After creation of uncontrolled liver hemorrhage, animals were randomized to 90 minutes of treatment: Control (full, unregulated flow; n=5) AO (no flow; n=10), and PRH with VAC (dynamic distal flow initiated after 20 minutes of AO; n=10). In the PRH group, distal flow rates were regulated between 100–300mL/min based on a desired, preset range of proximal mean arterial pressure (MAP). At 90 minutes, damage control surgery, resuscitation, and restoration of full flow ensued. Critical care continued for 4.5 hours or until death. Hemodynamic parameters and markers of ischemia were recorded. Results Study survival was 0%, 50%, and 90% for control, AO, and VAC respectively (p<0.01) (Figure). During intervention, VAC resulted in more physiologic proximal MAP (84mmHg±18 vs. 105±9mmHg, p<0.01) and higher renal blood flow than AO animals (p=0.02). During critical care, VAC resulted in higher proximal MAP (73 mmHg±8 vs. 50 mmHg±6, p<0.01), carotid and renal blood flow (p<0.01), lactate clearance (p<0.01), and urine output (p<0.01) than AO despite requiring half the volume of crystalloids to maintain proximal MAP ≥50 mmHg (p<0.01). Conclusion Permissive regional hypoperfusion with variable aortic control minimizes the adverse effects of distal ischemia, optimizes proximal pressure to the brain and heart, and prevents exsanguination in this model of lethal hemorrhage. These findings provide foundational knowledge for the continued development of this novel paradigm and inform next generation endovascular designs.

Resuscitative endovascular balloon occlusion of the aorta performed by emergency physicians for traumatic hemorrhagic shock: a case series from Japanese emergency rooms

“…In the present case series, none of our patients had apparent reperfusion injury. A previous animal study described that calcium administration and insulin and glucose therapy were required for hyperkalemia secondary to reperfusion injury after prolonged REBOA use [ 28 ]. Therefore, we need to be cautious about reperfusion injury and blood tests, especially the serum potassium level, and arterial blood gas analysis should be performed frequently to find early evidence of reperfusion injury.…”

A Novel Automated Endovascular Variable Aortic Control Device to Expand Function of Standard REBOA Catheters

“…With the increase in REBOA use for hemorrhage control, innovations to address certain key limitations have swiftly ensued. REBOA, while effective at controlling hemorrhage at bleeding points below the level of occlusion, is limited by the adverse effects of proximal aortic hypertension and progressive ischemic burden to distal tissue beds [1,2,5,7,13]. Therefore the technique of partially inflating a balloon catheter was proposed to slow bleeding and improve blood flow to the heart, lungs, and brain, while mitigating the ischemic insult below the balloon.…”

“…Our group's prior studies with robotic control systems have demonstrated that the precise regulation of ultra-low downstream aortic flow rates can balance the competing management priorities of hemostasis, blood pressure augmentation, and distal organ perfusion in the face of uncontrolled hemorrhagic shock [13][14][15]. This novel therapeutic concept, termed regionalized perfusion optimization (REPO), is predicated on a method that can precisely and dynamically control the flow of blood to the abdominal aorta, responding in real time to changing patient physiology.…”

“…As an initial step toward the development of an endovascular variable aortic control (EVAC) device that can autonomously vary the degree of aortic occlusion, we developed a novel extracorporeal flow circuit to achieve precision regulation of aortic blood flow [14]. This and other experimental aortic flow regulation devices have achieved REPO successfully in multiple large animal models of controlled and uncontrolled hemorrhage, improving outcomes compared to REBOA for multiple physiologic endpoints including mortality, hemodynamics, and end-organ function [13,16]. Yet, these initial studies did not employ endovascular devices that could readily translate into a clinically viable technology.…”

Endocrine Effects of Simulated Complete and Partial Aortic Occlusion in a Swine Model of Hemorrhagic Shock

“…3 During EVAC, the balloon volume is precisely regulated to allow a small amount of blood flow to distal vascular beds to minimize ischemia and limit hemorrhage while still sustaining proximal arterial blood pressure. 4,5 Although prior studies 6 have demonstrated cardiovascular benefits along with reduced isotonic crystalloids requirements following simulated EVAC when compared to simulated complete REBOA, the mechanisms for these effects have not been elucidated. Here we propose to investigate endocrine responses as a possible contributor to simulated EVAC responses by analyzing frozen serum samples from a previous experiment.…”