Resuscitative endovascular balloon occlusion of the aorta management guided by a novel handheld pressure transducer

Compact Arterial Monitoring Device Use in Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA): A Simple Validation Study in Swine

Introduction Hemorrhage is the leading cause of preventable death in trauma in both the military and civilian settings worldwide. Medical studies from Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) informed change in military prehospital medicine by influencing widespread tourniquet distribution and training on their use to stop life-threatening extremity hemorrhage. In the military setting, there has been a significant reduction in preventable death due to extremity exsanguination since the widespread implementation of tourniquets within the Department of Defense. However, noncompressible hemorrhage remains a significant cause of mortality, especially in the prehospital setting. In select patients, resuscitative endovascular balloon occlusion of the aorta (REBOA) is an adjunct that can be utilized to slow or stop non-compressible hemorrhage until the patient reaches definitive care. However, frontline medical providers face the challenge of reliable, accurate blood pressure measurement in REBOA patients. REBOA, used in conjunction with a small disposable pressure monitor, can bridge the gap in capabilities, creating a more balanced resuscitation and reducing blood product requirements with the added benefit of invasive blood pressure monitoring capability. The authors of this study propose the sustained use and further validation of a small, disposable pressure monitor in REBOA to monitor beat-to-beat variation in both hemodynamically stable and unstable patients and seek to offer a pathway for use in austere environments. Materials and methods Yorkshire swine (n = 4) were selected for partial REBOA (pREBOA) placement and compass transducer measurement in conjunction with a vascular experimental protocol. Appropriate vascular and arterial line access was obtained, hemorrhagic shock was initiated, and REBOA with an in-line Compass™ device (CD) pressure transducer (Centurion Medical Products, Williamston, MI) was used to occlude the aorta. Mean arterial pressures were measured via the CD, recorded, and compared to the control arterial line at hypotensive, normotensive, and hypertensive pressures. Results At hypotensive pressures, 30% of the CD readings fell within 1 mmHg of control arterial line readings, and 52.3% were within 2 mmHg. At normotensive pressures, 46% of the CD readings fell within 1 mmHg of control arterial line readings, and 64.2% were within 2 mmHg. At hypertensive pressures, 60% of the CD readings fell within 1 mmHg of control arterial line readings, and 82% were within 2 mmHg. All CD data points at all pressures were within 8 mmHg of the control arterial line readings. Conclusions In conclusion, the CD is a compact, inexpensive, portable pressure-sensing device that may potentially augment the safety and functionality of the REBOA in trauma patients both at the point of injury and in the hospital. This novel study conducted on four swine subjects demonstrated a remarkable correlation to the traditional equipment intensive arterial line setups, and issues of stasis and non-pulsatility were easily troubleshot. Future studies should investigate CD use in REBOA catheters under different physiological conditions, specifically arrhythmias, and in different environments (prehospital, air medical transport, and austere locations).

Validation of a miniaturized handheld arterial pressure monitor for guiding full and partial REBOA use during resuscitation

PURPOSE

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a well-validated method for the control of noncompressible truncal hemorrhage. In lower resource or battlefield settings, the need for arterial line setup and monitoring is problematic and potentially prohibitive. We sought to evaluate the accuracy and precision of a miniaturized portable device (Centurion COMPASS^®) versus standard arterial pressure monitoring using standard ER-REBOA and partial REBOA (pREBOA) as a high-fidelity and space-/time-conserving alternative.

METHODS

A total of 40 swine underwent a four-phase validation/precision study (each phase using five ER-REBOAs and five pREBOAs). Phases I/II evaluated accuracy with full and pREBOA in uninjured animals. Phases III/IV duplicated the previous phases but in a severe hemorrhagic shock model. Carotid and femoral pressures were monitored with both intra-arterial pressure systems and the COMPASS^® device. The vascular flow was measured by aortic flow probes. Correlation and Bland-Altman analysis were performed.

RESULTS

There was a strong correlation in accuracy testing of proximal and distal COMPASS^® devices compared to standard intra-arterial pressure monitoring (r = 0.94, 0.8; p < 0.005) as well as during precision testing (r = 0.98, 0.89 p < 0.005) in the uninjured phases. Similar accuracy and reliability were demonstrated in hemorrhagic shock, with a strong correlation for the proximal and distal COMPASS^® devices (r = 0.98, 0.97; p < 0.005), as well as during precision testing (r = 0.99, 0.95; p < 0.005) in both full and pREBOA scenarios. Bland-Altman analysis showed extremely low bias between the COMPASS^® and arterial line for both proximal (bias = 1.9) and distal (bias = 0.8) pressure measurements.

CONCLUSION

The COMPASS^® provides accurate and precise pressure measurements during standard and partial REBOA in both uninjured and shock conditions. This device may help extend and enhance capability in any low-resource/battlefield settings, or even eliminate the need for standard intra-arterial invasive pressure monitoring and external setup.

THE PHYSIOLOGY OF AORTIC FLOW AND PRESSURES DURING PARTIAL RESUSCITATIVE ENDOVASCULAR BALLOON OCCLUSION OF THE AORTA (pREBOA) IN A SWINE MODEL OF HEMORRHAGIC SHOCK

BACKGROUND

Partial resuscitative endovascular balloon occlusion of the aorta (REBOA) has shown promise as a method to extend REBOA, but there lacks a standard definition of the technique. The purpose of this study was to investigate the relationships between distal and proximal mean arterial blood pressure (MAP) and distal aortic flow past a REBOA catheter. We hypothesize that a relationship between distal aortic flow and distal MAP in Zone 1 partial REBOA (pREBOA) is conserved and that there is no apparent relationship between aortic flow and proximal MAP.

METHODS

A retrospective data analysis of swine, cohort one underwent 20% controlled hemorrhage and then randomized to aortic flow of 400 ml/min or complete occlusion for 20 minutes (n = 11). Cohort two underwent 30% controlled hemorrhage followed by complete aortic occlusion for 30 minutes (n = 29). Then they all underwent REBOA wean in a similar stepwise fashion. Blood pressure was collected from above (proximal) and below (distal) the REBOA balloon. Aortic flow was measured using a surgically implanted supraceliac aortic perivascular flow probe. The time period of balloon wean was taken as the time point of interest.

RESULTS

A linear relationship between distal MAP and aortic flow was observed (R 2 value: 0.80), while no apparent relationship appeared between proximal MAP and aortic flow (R 2 value: 0.29). The repeated measures correlation coefficient for distal MAP (0.94, 95% Confidence Interval: 0.94 - 0.94) was greater than proximal MAP (-0.73, 95% Confidence Interval: -0.74 - -0.72).

CONCLUSION

The relationship between MAP and flow will be a component of next generation pREBOA control inputs. This study provides evidence that pREBOA techniques should rely on distal rather than proximal MAP for control of distal aortic flow. These data could inform future inquiry into optimal flow rates and parameters based on distal MAP in both translational and clinical contexts.

LEVEL OF EVIDENCE

Level V.