Will endovascular aortic resuscitation balloon occlusion move the needle on out-of-hospital cardiac arrest mortality?
Out-of-hospital cardiac arrest (OHCA) continues to be extremely fatal despite cardiopulmonary resuscitation (CPR) and many other advances in prehospital care. It takes the lives of nearly 350,000 Americans every year and has a dismal 10% survival rate to hospital discharge.[1] The greatest challenge for OHCA is to achieve sustained return of spontaneous circulation (ROSC) in refractory cardiac arrest and therefore represents a great opportunity for advancement.[2,3]
Extracorporeal cardiopulmonary resuscitation (CPR-E) for OHCA is increasingly being used in various pockets around the world and has been shown to improve organ survival and recovery in refractory cardiac arrest. However, the treatment is extremely resource intensive and not feasible for the vast majority of patients.
An emerging alternative treatment for achieving ROSC in refractory cardiac arrest is resuscitation balloon endovascular occlusion of the aorta (REBOA).
REBOA has been used primarily for non-compressible traumatic torso bleeding as a gateway to definitive hemostasis control in the operating room. This involves placing a balloon catheter from the femoral artery to the aorta of bleeding patients. When the aortic occlusion balloon is inflated, there is improved coronary and cerebral blood flow above the balloon with controlled permissive hypotension below the balloon. Apart from trauma, it has been used for other bleeding applications like postpartum hemorrhage and gastrointestinal bleeding. It has even been deployed in the pre-hospital setting and was first performed roadside for a trauma patient by London Air Ambulance in 2014.
By combining better coronary and cerebral perfusion with its relatively simpler approach and wider availability than E-CPR, REBOA may ultimately prove to be the best pre-hospital treatment for OHCA to achieve ROSC or may even act as a pre-hospital bridge for in-hospital E-CPR.
REBOA to help return spontaneous circulation in the event of cardiac arrest
Various animal studies have investigated REBOA for non-traumatic cardiac arrest and show increased central aortic pressure when the balloon is deployed in the descending thoracic aorta, as well as improved coronary perfusion, cerebral perfusion, dioxide end-tidal carbon (ETCO2), and mortality.
One of the difficulties with traditional advanced cardiac life support (ACLS) measures is that they rely heavily on epinephrine to achieve ROSC.
Epinephrine helps improve central aortic pressure, but often at the expense of brain tissue. Unfortunately, only 8% of American patients with OHCA survive with a good neurological outcome.[4] Interesting way, a recent animal study by Alice Hutin and her group at the University of Paris showed that REBOA was as effective as epinephrine in facilitating ROSC in pigs, but unlike epinephrine, REBOA increased cerebral blood flow and could therefore avoid adverse cerebral effects during CPR.[5]
The animal studies were so compelling that they paved the way for two small pre-hospital human feasibility trials, namely Lawrence Gamberini’s Italian series, which showed sustained ROSC in four out of eleven patients.[6] As well, Dr Jostein Bredeit is norwegian study showed sustained ROSC in six of 11 patients.[7]
Brede has taken this further and is currently conducting a 200 patient randomized controlled trial (REBOArrest.com) which has already enrolled its first patients.[8] There are also institutions, such as Yale New Haven Hospital in Connecticut, run by James Daly, MD, and University Hospital in Salt Lake City, Utah, run by Austin Johnson, MD, who use REBOA as part of research protocols for OHCA in their emergency departments.
How REBOA technology works
Early aortic occlusion devices were borrowed from endovascular aortic aneurysm repair tools for which they are used to mold aortic stents. These larger profile 12 French aortic occlusion balloons often require surgical cuts of the femoral artery and would not be suitable for pre-hospital use. Recently, low profile devices have been developed which reduce the time and skill required for deployment.
The COBRA-OS (Front Line Medical Technologies) is the lowest profile aortic occlusion device with 4 French FDA clearance. In a first-in-man feasibility trial, the device was deployed in an average of 70 seconds from skin to aortic occlusion. The device is guidewireless, does not require an over-the-wire technique, and has a soft J-shaped leading edge to prevent cannulation of the aortic branch. It also has markers on the device to indicate the positioning of the thoracic aorta 48 cm from the femoral sheath. A simple, unobtrusive device like this may be the ideal pre-hospital aortic occlusion device and may even be deployed by advanced non-physician paramedics in the future.
The latest advances in REBOA technology demonstrate the potential feasibility of deployment in pre-hospital settings and offer several advantages over more expensive and complicated treatments like E-CPR. Animal studies consistently show that REBOA causes major physiological improvements that should help tip the balance towards ROSC during CPR. In addition, the first human feasibility trials are promising.
It will be an exciting time over the next few years as data grows on the usefulness of REBOA for in-hospital and out-of-hospital cardiac arrests and ultimately its place in relation to E-CPR. . It will be important to continue to advance ideas and technology responsibly to help save our sickest patients. Implementing cost-effective treatments earlier in our patients’ care journeys will be key to removing some of the biggest barriers to treatment.
About the Author
Adam Power, MD, is an associate professor at Division of Vascular Surgery at Western University in London, Ontario, Canada. Power completed a residency in general surgery at McMaster University and a fellowship in vascular surgery at the Mayo Clinic. Power’s research interests include innovation and medical device development and he is the Chief Medical Officer of Front Line Medical Technologies Inc.
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