Mar 20, 2016
Are you ready for REBOA? Zaf Qasim (@emeddoc) gives the ins and outs of Resusciataitve Endovascular Balloon Occlusion of the Aorta
Mel Herbert and I talk about our favorite podcasts as well as Mel's new show Shabam!
What are the steps of REBOA?
To understand REBOA you have to know a little bit of anatomy. We talk about 3 aortic zones when we talk about REBOA. Zone 1 is from the left subclavian artery to the celiac trunk, Zone 3 is from the lowest renal artery to the aortic bifurcation, and Zone 2 is the area in between. We don’t like to talk about zone 2 – that’s essentially a no go zone because if you inflate the balloon here, you may not occlude the vessel that’s causing the bleeding.
So once you’ve decided to place REBOA, and we’ll talk about indications and contraindications a bit more in a second, the key step is accessing the common femoral artery and putting in a standard 18G arterial line. Next, you’re going to be passing a long guidewire through that arterial line up to the level of the left subclavian. We use a stiff, 260cm wire to do this, and measure it using external landmarks. If you have the time, you’ll get a chest xray to confirm the position. Next, you’ll replace the arterial line with an introducer sheath – the one we use is actually pretty huge, 12 French, and that allows passage of the actual balloon catheter. You’ll need to measure the length of insertion against your external landmarks, and that’s the xiphisternum for Zone 1, and the umbilicus for Zone 3, pass the catheter over the wire through the sheath, and inflate the balloon with saline in the appropriate zone until you feel a change in resistance as the balloon abuts the aortic wall. You should at this time see a pretty dramatic rise in your blood pressure.
Who gets this? Pelvic fractures, get that, but I’m hearing about it in any sort of hemorrhagic shock, sort of a poor man’s cross clamping of the thoracic aorta without having to crack the chest
So yeah, you hit the nail on the head – this is the alternative to cracking open the chest and putting a big clamp on the aorta just for the purposes of stopping bleeding below the diaphragm and improving cardio-cerebral perfusion.
Let’s talk first about who’s not going to get it. If you think your patient has some sort of horrible chest injury, like a cardiac tamponade or a traumatic proximal aortic dissection, you do NOT want to put a balloon up there. That’s just going to make that patient’s day a whole lot worse. You can easily rule those things out with what you do already in the trauma bay, the FAST and the chest xray. If you see a tamponade, you’re going to be opening the chest.
But if you think this patient has what’s termed non-compressible torso hemorrhage, that is, devastating bleeding from areas below the diaphragm in the abdomen, pelvis, or retroperitoneum, places you can’t put a tourniquet or direct pressure to, these are the folks who will benefit from REBOA. This can be from blunt or penetrating trauma, and even non-traumatic hemorrhage as I’ll talk about in a second. If you’re suspecting abdominal bleeding, they’ll get a Zone 1 balloon, for pelvic bleeding it’s Zone 3.
The beauty of this procedure is that you don’t have to wait for the patient to die before you proceed like you do with the thoracotomy. You can proactively place this in the transient or non-responder. Since you’re being proactive about this and stemming bleeding before the patient undergoes that horrendous insult called death, I think you have the potential to have a higher percentage of what you really want at the end of this - neurologically intact survivors, and this is what we’re already seeing.
At Shock Trauma we’ve also placed REBOA in witnessed traumatic cardiac arrest, but I think you really need to have witnessed that arrest for this to be a useful procedure.
People wonder how long this procedure takes to do what with all the wire and device changes that are occurring. The answer, and we have this data from the interim analysis of an ongoing national study called AORTA, is that it is not statistically different to the time it takes to do a thoracotomy and get an aortic cross-clamp on right. This really annoys the naysayers!
Remember, before you do this you’ll already have gotten your IV access, started your damage control resuscitation, placed the pelvic binder, done all that. If they’re STILL circling the drain, so the transient or non-responder, and you think they’re highly likely to code, REBOA is the next step to buy them those precious minutes to get to the OR or in some cases to IR. But don’t forget the basics!
What would it take for me to go from where I am today, a true neophyte, to REBOA operator?
I think as with any new procedure it’s critical that people get the right training to do this, as it is certainly not without risk. Having said that, REBOA builds on skills that emergency physicians already have – the use of ultrasound to localize the common femoral artery and the use of a Seldinger technique to insert the various pieces of equipment.
Essentially the first critical step, placing the femoral arterial line, is something we have been trained to do. The caveat is you have to be sure you’re in the common femoral artery. It’s always a little higher than you think it will be, but with dynamic ultrasound, you can be trained to do that safely and efficiently. My advice is place that arterial line in your sick patient early, while you still have a decent caliber vessel to access. If they get better, hey you’ve got a central arterial line. If not, though, you’ve already done the rate-limiting step of the procedure.
Upsizing to the 12 French sheath can be daunting – think of your usual Cordis (or introducer) but on steroids! You have to be very careful to ensure you’re inserting this without feeling any major resistance, and that your dilator doesn’t inadvertently get pushed out as you’re putting the sheath in. But again this step builds on principles we as EPs already have.
In the US, this technique was trialed and brought out primarily by trauma surgeons, and the reason behind that was not only the way trauma care is delivered in the US but also the high potential for injury when you stick a huge sheath into the femoral artery. Additionally, you can’t just pull that thing out at the end of the day, get the medical student to hold pressure, and go get some coffee. No. It needs a formal assessment and closure of the hole made in the artery as well as ensuring good limb perfusion at the end of the procedure, and that’s a skillset we as emergency physicians don’t have. You may also need to perform a cutdown on the groin to access the artery, especially in the setting of cardiac arrest, and that’s a skill we don’t have from our training but one that CAN be learnt.
So on the back of that, the initial training courses that came out here were really also directed at the surgeons, and there were initially two in the country. I teach one of them, the Basic Endovascular Skills for Trauma course down in Baltimore, and our candidates are primarily surgeons. We do both simulator and cadaver work with them. Currently the only EPs that have been trained on our course are those with dual training in critical care and affiliated with Shock Trauma.
But this will evolve and change for two reasons I think. First, emergency physicians have already demonstrated that, with appropriate training, they can safely and effectively perform procedures with big catheters like ECMO – just look at the Reanimate course and the work out of Sharp Memorial in San Diego. Second, and this is the most exciting news, back in October, the FDA approved a new, purpose built device called the ER-REBOA catheter (and I have no financial interest in this device by the way). This can be placed through a much smaller 7-French sheath – that’s the size of the Cordis we all know and love. Additionally, there’s no lengthy wire that needs to be put in before hand, you can just do your measurements using this catheter device and place it in the appropriate zone.
So to summarize, yes, emergency physicians can build on their existing skillset to learn this procedure, and with appropriate training and within a system of robust quality assurance, will be able to safely deliver this.
Is this ready for the community ED?
That’s a great question. It’s certainly a very attention-grabbing procedure that’s in the headlines and I think ultimately this will have a key role in the community ED. You’re essentially aiming to extend your golden hour by placing this. Imagine you’re at a single coverage community ED and you get an unexpected drop-off who is a bad motorcycle victim who’s bleeding out from his abdomen or pelvis, you place this device, get control, and are able to ship them off to the regional level 1. Not only that but think of the patient with a non-traumatic bleed, a ruptured ectopic for example – the same principle applies and you can use REBOA to buy them time for either your own surgeon to come into the hospital or to get them out to your local ivory tower. That is the ultimate goal.
Are we there yet? I think not quite. Currently as you say REBOA is being performed at big academic centers, like the intergalactic shock trauma center. These places are able to get the patient to the OR fairly quickly and have the complement of specialties in house or very rapidly accessible to deal with any issues or complications that may arise as a result of placing REBOA. There are some issues that still need to be worked out before we’re ready to say that community docs within a trauma network will be able to utilize this technology. These are primarily centered on training and system logistics. But I think one of the major limitations is time.
What’s the treatment arc of REBOA? How long can it stay in? What should be your mindset once you place it?
The mindset once you put in REBOA is “I need to get this person to definitive care as soon as humanly possible.” These aren’t people who will tolerate you scratching your head or rubbing your chin. They’re staring you down and saying “I’m sick as hell, fix me” Once the balloon is up you need to already have a plan in place of how you’re going to fix the problem. You may have some time depending on how your shop is set up to get some focused imaging, but the default destination is most likely going to be the OR. That highlights a couple of things.
First of all, you need to limit balloon inflation time. Think about it, if you’re putting a balloon in Zone 1 and occluding flow to everything below the diaphragm, you’re taking out a lot of real estate – the kidneys, the gut, even the spinal cord. Your patient is not going to like that. The animal studies and the limited human studies show elevations in lactate proportional to the duration of balloon inflation. The animal studies show that up until about the 40-60-minute mark, appropriate resuscitation will clear that lactate, but beyond that it can precipitate a devastating cycle of physiologic injury that you may not recover from. On top of that, when you let the balloon down after prolonged inflation, you run the risk of reperfusion injury – akin to those people you treat with crush syndrome. Zone 3 balloons are a bit better tolerated but still have the same principle to them.
The Japanese papers really highlighted this. They have been doing REBOA much longer than we have, and their papers were showing complications not clearly evident in our limited US data. Their system is somewhat different: they don’t see a lot of trauma and so their surgeons aren’t in house. Their EPs are trained to put in REBOA and call the surgeon in. Because of this their time to get to the OR may average well over an hour, and that was one reason I think those patients were having less than optimum outcomes. The other being they sometimes resorted to using the balloon as a last-ditch, throwing the kitchen sink at the problem effort. So it goes to further emphasize the timing issue – if you’re going to use it, use it early, and then get them to definitive care quickly.
The second thing this highlights is if you’re thinking of bringing this into your service, you need to train your team to hustle efficiently once the procedure is performed. There can’t be delays because of rubbernecking or high-fives that you’ve done this sexy new procedure – do that after you’ve fixed the problem for sure, but not at the time. Remember if you’re the one doing the procedure, you put on blinders and become task-focused. You develop tunnel vision and lose that situational awareness. This patient is still extremely sick, and so needs ongoing resuscitation. You need to designate someone to take over and lead the resuscitation so that the blood products still go in, the right services are involved, and the team is coordinated to move this patient to the OR once the balloon has gone up.
The way I wrote the protocol at our shop for example is that in our trauma codes, the trauma surgeon will move from supporting the senior trauma resident as the team leader to becoming the proceduralist. The emergency physician moves from supporting the airway resident at the top of the bed to becoming the designated team leader and the direct support for the trauma resident. Our nurses help by clearly documenting times of balloon inflation. In the OR, the anesthesiologist with help from the circulating nurse becomes tasked with reminding the surgeon using closed-loop communication about the duration of balloon inflation so that everyone is geared to limit that time the balloon is up. That requires team training beyond just learning the procedural steps.
This has all been pixie dust and fairy parties so far, but what are the downsides of this procedure?
What’s wrong with fairy parties?! Definitely nothing comes for free though. We already spoke about the big issue of the physiologic consequences of balloon inflation, so keep an eye on those times. There’s the risk of losing situational awareness which we also touched on.
Additionally, you always run the risk of vascular injury – you can put the sheath into one of the smaller branch vessels and risk shearing that off, or creating dissection flaps. You might access the vein by mistake, guaranteed not to get you any style points. The balloon may inadvertently migrate, or potentially fail.
But a really huge issue is the risk of critical limb ischemia and limb loss. There are reports from abroad of this having happened, and to date, the US has not had any reported cases of limb loss. The limb is at risk for a variety of reasons – the size of the sheath can completely occlude the main vessel to the leg, especially in smaller patients. Also, and you wouldn’t have thought this would happen in people who are so sick, is that our surgeons are often seeing clot around the sheath at the time of removal and vessel repair, which sets it right up for ischemic and embolic problems. I think one of the inadvertent benefits of needing to use a huge sheath currently in this country is that it dictates open repair and removal. So the surgeons have the opportunity to check limb perfusion right there in the OR at the end of the case and make sure the flow is appropriate, and I think that’s why we don’t have any reported US cases of limb loss from the use of REBOA. Be extra vigilant about limb perfusion – ANY difference between the two limbs, even a slightly different color, mandates vascular to come and assess that leg again.
A final point which isn’t exactly a complication but should be mentioned is the notion that REBOA is either not something worth doing or might be done for the wrong reasons and so more often than indicated. There are certainly naysayers, and yes it’s new and still being tested but it is already showing positive results and importantly has the benefit of producing neurologically intact survivors. It can certainly be incorporated as another tool in the box in managing these difficult patients in an attempt to get them to definitive care. On the other hand, new toys might get used when they shouldn’t be or in lieu of good basic tenets of trauma care. So to ameliorate that effect, bring it in within a strict protocol that undergoes a strict QA process – do it right and remember your basics.
Say I have a patient with a crushed pelvis, I put in a REBOA, is that patient OK for transfer to a bigger trauma center? Is bad pelvic fx in any way a contraindication?
Bleeding pelvic fractures are the ideal candidates to get a Zone 3 REBOA and be moved to the trauma center. Remember you should also put on the pelvic binder and continue your usual resuscitation but these are the guys who have a high mortality in the civilian literature. They will bleed out quickly- talk and die. The zone 3 position may also tolerate slightly longer balloon inflation times than zone 1.
What are your take home points?
REBOA is a promising procedure for managing devastating torso hemorrhage
The skills for it build on those that we as emergency physicians already have, but need to be refined through specific training and need to be delivered within a multidisciplinary system having a robust QA process
Balloon inflation times and the potential for limb ischemia are very real threats to its use
Both the technology and the data continue to evolve, so collaborate, share your experience, and watch this space
Qasim, Zaffer, et al. "Resuscitative endovascular balloon occlusion of the aorta." Resuscitation 96 (2015): 275-279.