Extending resuscitative endovascular balloon occlusion of the aorta: Endovascular variable aortic control in a lethal model of hemorrhagic shock

Abstract

Background: The duration of use and efficacy of resuscitative endovascular balloon occlusion of the aorta (REBOA) is limited by distal ischemia. We developed a hybrid endovascular-extracorporeal circuit variable aortic control (VAC) device to extend REBOA duration in a lethal model of hemorrhagic shock to serve as an experimental surrogate to further the development of endovascular VAC (EVAC) technologies.

Methods: Nine Yorkshire-cross swine were anesthetized, instrumented, splenectomized, and subjected to 30% liver amputation. Following a short period of uncontrolled hemorrhage, REBOA was instituted for 20 minutes. Automated variable occlusion in response to changes in proximal mean arterial pressure was applied for the remaining 70 minutes of the intervention phase using the automated extracorporeal circuit. Damage-control surgery and whole blood resuscitation then occurred, and the animals were monitored for a total of 6 hours.

Results: Seven animals survived the initial surgical preparation. After 20 minutes of complete REBOA, regulated flow was initiated through the extracorporeal circuit to simulate VAC and provide perfusion to distal tissue beds during the 90-minute intervention phase. Two animals required circuit occlusion for salvage, while five animals tolerated sustained, escalating restoration of distal blood flow before surgical hemorrhage control. Animals tolerating distal flow had preserved renal function, maintained proximal blood pressure, and rapidly weaned from complete REBOA.

Conclusion: We combined a novel automated, extracorporeal circuit with complete REBOA to achieve EVAC in a swine model of uncontrolled hemorrhage. Our approach regulated proximal aortic pressure, alleviated supranormal values above the balloon, and provided controlled distal aortic perfusion that reduced ischemia without inducing intolerable bleeding. This experimental model serves as a temporary surrogate to guide future EVAC catheter designs that may provide transformational approaches to hemorrhagic shock.

Figure 1. Study Flow

Figure 2

Schematic of Experimental Setup: A) Aortic cannulas placed in the carotid and femoral arteries are connected to the clamped circuit. B) Occlusion of the aorta with a CODA balloon and unclamping of the circuit diverted blood flow through the circuit. Data from the proximal pressure and inline flow monitors is relayed in real time back to the data acquisition system and on to the control box, which regulates flow in the circuit based on a prescribed algorithm.

Figure 3

Components of the Variable Aortic Control Device: Transonic® TS410 Flowmeter receives input from an inline flow probe Custom control system utilizing an Arduino® microcontroller Flow circuit consists of a linear actuator, pneumatic, and electric pinch valves Close-up view of the linear actuator demonstrates the roller bearing/tubing interface

Figure 4

Hemodynamic Data: A) Proximal MAP throughout the experiment. Note animals requiring crossover sustained precipitous drop upon EVAC, however rebounded upon re-occlusion. Following damage control, animals that tolerating sustained EVAC maintained a MAP near baseline for the remainder of the study. B) Circuit flow during EVAC phase. Averaged continuous MAP for five animals that tolerated EVAC showed sustained initial flow at 150 mL/min, with flow rate of 300 mL/min beyond T40 and immediately weaned from REBOA.

Figure 4

Hemodynamic Data: A) Proximal MAP throughout the experiment. Note animals requiring crossover sustained precipitous drop upon EVAC, however rebounded upon re-occlusion. Following damage control, animals that tolerating sustained EVAC maintained a MAP near baseline for the remainder of the study. B) Circuit flow during EVAC phase. Averaged continuous MAP for five animals that tolerated EVAC showed sustained initial flow at 150 mL/min, with flow rate of 300 mL/min beyond T40 and immediately weaned from REBOA.