Tag Archives: REBOA

REBOA For Pelvic Fractures

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is one of the newer shiny toys that trauma professionals have adopted over the past 8 years or so. It is used to buy time for a patient who is near arrest in order to temporarily stop bleeding and get them to the operating room.

And as with all new toys, everyone wants one! I have always advised caution. Adopt a data-based approach to toy usage. Unfortunately information has been accumulating ever so slowly on this one. To help remedy this, the AAST created a registry in 2013 to consolidate the low REBOA experience numbers accruing across the US.

A group of seven surgeons representing higher-volume REBOA centers collaborated to review the AAST AORTA registry, which prospectively collects data on patients who undergo aortic occlusion. They retrospectively reviewed over six years of data on adult patients receiving REBOA for pelvic injury. They examined demographic, procedural, and outcome data in patients who underwent this procedure, both with and without other interventions like preperitoneal packing, angioembolization, or external fixation. For inclusion in the study, patients needed to have sustained blunt trauma and survived beyond the emergency department.

Here are the factoids:

  • Of the 207 patients with pelvic (Zone 3) REBOA in the registry, only 160 met inclusion criteria
  • Patients who only had REBOA suffered a mortality rate of 40% (5% in OR and 35% in the ICU)
  • Patients who had REBOA plus one of the other interventions had a 31% mortality rate (6% in OR and 25% in ICU)
  • Patients who had REBOA plus two other interventions also had a 31% mortality rate (12% in OR and 30% in the ICU)
  • Adding external fixation with or without another adjunct appeared to decrease mortality by half (from 50% to about 25%)
  • Complications were very common in all subsets, ranging from 35% to 86%
  • Patients receiving more interventions typically were more severely injured
  • No combination of REBOA and adjuncts was superior, but addition of an external fixator did appear to improve survival
  • Patients receiving angiographic embolization had a higher incidence of AKI, sometimes resulting in the need for dialysis
  • There were no significant outcome differences with REBOA use alone or with additional adjuncts

Bottom line: This was a primarily a descriptive study of how REBOA is integrated into pelvic fracture care at select US trauma centers. It was not really designed to compare the efficacy of REBOA vs preperitoneal packing vs angioembolization vs external fixation of the pelvis.

But it does show that survival remains dismal in these patients and the complication rates of REBOA + adjunct use are considerable. The authors correctly conclude that REBOA is being used in the treatment of pelvic fractures, frequently with the addition of other adjuncts. They state that the benefit of more interventions must be balanced against the potential for complications. And finally, they note that there is a need to fill in the evidence base if we are ever to adopt REBOA as a standard of care for select pelvic fractures.

What does this mean to all of you who are thinking of playing with this toy? Proceed with caution! The learning curve is steep. The complication rate is high. The opportunity for mayhem is great. This means that you must proceed deliberately. Get some advanced training with this technique. Use your performance improvement program to impartially critique its use with every deployment. And submit your experience to the national registry so we can all learn from your experience and figure out how to optimize use of this tool.

Reference: Patterns and outcomes of zone 3 REBOA use in the management of severe pelvic fractures: Results from the AAST Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery database. J Trauma 90(4):659-665, 2021.

 

REBOA: A Comparison Of The Hardware From Two Companies

I started off the week describing a study using a new version of the REBOA catheter (Resuscitative Endovascular Balloon Occlusion of the Aorta) that was smaller than the more commonly used one. Today I’ll put both side by side and describe the similarities and differences.

First, let’s start with the current market leader, the ER-REBOA catheter by Prytime Medical in Boerne, TX. Here’s a picture provided by the company:

And here’s a photo of the Frontline Medical Technologies COBRA-OS, based in London, Ontario, Canada. This acronym stands for Control of Bleeding, Resuscitation, Arterial Occlusion System. Now, REBOA is used by surgeons as a general descriptor for this type of technology. I assume that Frontline does not include REBOA in the name of this product since Prytime has incorporated it into theirs.

There are a number of similarities, as well as some key differences. Let’s start at the tip and make our way back to the syringe.

Catheter tip: Prytime has a trademarked “P-tip” which has a little extra curl compared to the Frontline’s flexible j-tip. The Prytime version is designed to “help reduce catheter migration and aid in positioning. Although a guidewire can be inserted into either to assist in repositioning, it does not enter the P-tip. And note, neither device requires a wire for insertion.

Arterial line port: This is only found on the Prytime device. This is located just distal to the balloon so arterial pressures can be measured above the catheter after inflation. This port extends through the catheter, terminating in a hub that can be connected to standard pressure transducer equipment. The Frontline device is too small to incorporate this feature.

Balloon: The Prytime balloon is a more standard ovoid shape. The company provides guidelines of 8cc inflation for Zone I and 2cc for Zone III. This can be adjusted based on confirmation of occlusion provided by the arterial pressure wave form. The Frontline device has an “ice cream cone shaped” balloon with the taper proximally and a “safety shoulder” to protect the balloon. The company claims that this design helps reduce the likelihood of rupture. The balloon will accept 13cc at maximum inflation. Since there is no arterial line, alternate means (palpation, ultrasound, or a transducer in the insertion port) must be used to determine degree of occlusion.

Markers: The Prytime device has radio-opaque markers at either end of the balloon, as well as length markers on the proximal portion of the catheter. The Frontline catheter has the same markers around the balloon, but only two large visible marks on the proximal catheter. These are marked for placement in Zone I (48cm) and Zone III (28cm) in average size patients.

Sheath: The Prytime product has a peel-away sheath that is used to cover the P-tip to straighten it. This unit is then inserted into the previously placed access port. Once inserted the sheath is peeled away after the balloon has passed the end of the port. The Frontline device does not have a sheath, but includes a reusable j-tip straightener on the catheter. This straightens the tip as it passes through the port.

Access port: These are included with both products and are inserted using typical Seldinger technique. Both have a side port for fluid infusion. The side port of the Frontline product can be used as an arterial pressure monitor. The port is 7Fr in the Prytime product and 4Fr for Frontline. This smaller size may decrease the incidence of vascular thrombosis or vessel injury requiring repair after removal.

Bottom line: I’ve described two different products that allow trauma professionals to use the REBOA concept. This evolution demonstrates the usual cycle of new product and feature refinement that we have come to expect in medical devices.

Is one “better” than the other? That’s probably not the right question. More likely, it will boil down to which one is right for a particular patient or situation. Only time, and lots of additional research, will tell.

References: 

  • Prytime Medical – www.prytimemedical.com
  • Frontline Medical Technologies, Inc. – www.frontlinemedtech.com

I have no financial interest in either of these companies

The Shrinking REBOA Catheter

REBOA (resuscitative endovascular balloon occlusion of the aorta) is one of the relatively new toys in our trauma toy chest. Although it’s been used for decades by vascular surgeons, believe it or not it only made the jump into the trauma world less than 10 years ago.

The original catheters used during the early days, and primarily in swine models, required a 15 French sheath for insertion. As might be expected, insertion of these huge sheaths into the common femoral artery can cause significant vascular injury. Equipment manufacturers have been steadily reducing the size of the REBOA catheter, first to 12 Fr and then to the 7 Fr size commonly used today.

The surgery group at the London Health Sciences Center in London, Ontario, Canada performed a pilot study of a new and much smaller sheath and REBOA catheter. It is made by Front Line Medical Technologies, also located in London. This was a proof of concept for the device and was performed in seven neurological death organ donors prior to their donation.

The kit consists of a 4 Fr sheath introducer with a 21 gauge needle and a guidewire, plus the REBOA catheter itself. Here is an image of the catheter:

This catheter includes several innovations not found in current catheters used in the US. I will do a side by side review of these later this week.

Here are the factoids:

  • Seven organ donors were studied after appropriate consent from the hospital IRB, organ procurement agency, organ donor procurement team, and family
  • A single general/vascular surgeon performed all insertions
  • A left sided arterial line using the 4 Fr sheath was inserted for monitoring before the procurement began
  • A right sided 4 Fr sheath was inserted for catheter insertion after the procurement incision was made
  • Average sheath insertion time was 48 seconds, and deployment time for the catheter was an average of 70 seconds (max time was 105 seconds)
  • Occlusion was confirmed by the left femoral arterial pressure monitor and by palpating the aorta below the baloon

Bottom line: This was a very simple study of the feasibility of using a smaller REBOA catheter. It measured both ease of insertion and presence of full occlusion. This is an exciting study, because there is the potential for easier insertion and fewer vascular complications at the insertion site. Obviously, these factors are not yet known, and only further work will make this clear. 

Nonetheless, easier and safer insertion has the potential to increase the use of REBOA. This will allow us to get quicker answers to the nagging questions about whether it is actually a valuable resuscitation tool and help us figure out how and in whom it is best used.

Reference: Size matters: first-in-human study of a novel 4 French REBOA device. Trauma Surgery & Acute Care Open 2021;6:e000617. doi: 10.1136/tsaco-2020-000617

Best Of AAST #2: REBOA And Unstable Pelvic Fractures

REBOA is the new kid on the block. Human papers first started appearing in the trauma resuscitation literature about six years ago. Since then, we’ve been refining the details: how to use it, who to use it in, as well as a lot of the technical tidbits.

The group at Denver Health Medical Center compared their experience with pelvic packing vs REBOA for patients with unstable pelvic fractures. They reviewed four years of experience to see if they could further clarify some of the benefits of this technique.

Here are the factoids:

  • A total of 652 patients presented with pelvic fractures, and 78 underwent pelvic packing for control of hemorrhage
  • Of these 78 patients, 31 also had a REBOA catheter placed and 47 did not
  • The ISS in the REBOA+ group was significantly higher at 49 vs 40
  • Although systolic blood pressure and heart rate were statistically more abnormal in the REBOA+ group, these values were not clinically different (SBP 65 vs 72, HR 129 vs 117)
  • The amount of transfused red cells and plasma was twice as high in the REBOA+ patients (RBC 16 vs 7, FFP 9 vs 4)
  • There was no difference in survival rate (REBOA 84% vs packing 87%)

The authors concluded that this study suggests REBOA plus pelvic packing provides life-saving hemorrhage control in otherwise devastating injuries.

Here are my comments:  So the authors inserted REBOA catheters in addition to pelvic packing in half of their patients that were more severely injured, gave them twice as much blood product, and had the same number of survivors. But the primary outcome was the same. It’s very difficult to tease out which factors are responsible when there are such significant differences between the groups with respect to factors that have a definite impact on survival.

Did the use of REBOA equalize survival in the more severely injured patients, or was it the additional blood products, both, or neither? It’s really not possible to say. REBOA may be a valuable adjunct to trauma resuscitation, but we still need more information so we can be sure we are using it in the right patients.

And some questions for the authors:

  • How did you select patients for REBOA? This could make a big difference and inject significant selection bias. Could your surgeons have been primed to use this in patients who looked sicker?
  • Have you considered matching subsets of your patient groups with similar ISS and transfusion volumes, and then comparing mortality? This could be revealing, but I suspect the numbers will be too small to have the statistical power to show any differences.

This will be a very interesting paper to listen to! I look forward to more details.

Reference: Inflate and pack! Pelvic packing combined with REBOA deployment prevents hemorrhage related deaths in unstable pelvic fractures. AAST 2020 Oral Abstract #4.

AAST 2019 #1: Survival Benefit Of Pelvic REBOA

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is one of the new, shiny toys in the trauma professional’s toy chest. Research papers on the topic are increasing exponentially, but human data was not even published until 2014! This is still a new device and we are trying to learn more about it.

The AAST set up an Aortic Occlusion for Resuscitation in Trauma and Acute Care (acronym is AORTA, ugh!) to help accumulate data for this not-often used technique. Hopefully, compiling comprehensive use and outcome data will speed our appreciation of the usefulness of this device.

A multi-institutional trauma group massaged the AORTA registry to examine the potential benefits of using the technique in patients with pelvic fractures leading to severe blood loss. They specifically looked for patients with the balloon inflated in Zone 3 to decrease bleeding from below the aortic bifurcation. Here’s a diagram of the zones:

The authors identified a total of 109 patients pelvic fractures with bleeding from below the bifurcation.

Here are the factoids:

  • The presenting patients arriving without CPR all had similar base deficit, lactate, and systolic BP. This shows us that the two groups are the same, but only for these three parameters. GCS was lower in the open aortic occlusion group. This could certainly contribute to a higher overall mortality in this group.
  • Overall mortality was significantly lower in the REBOA group that included those arriving with CPR in progress (35% vs 80% for open occlusion)
  • And when CPR patients were excluded, the mortality was significantly lower (33% vs 69%)
  • One in ten patients undergoing REBOA suffered vascular access complications (vascular repair required, limb ischemia, distal embolization, or amputation)
  • Complications among survivors were not different between the groups, nor were hospital or ICU lengths of stay or blood usage

The authors state that their data shows a “clear survival advantage” in those patients who undergo REBOA. Furthermore, this was accomplished without increasing systemic complications. They finally conclude that REBOA should be “strongly considered” for patients in shock due to pelvic trauma.

Not quite so fast here. There are several more factors in play than meet the eye.

First, a study that massages a REBOA database was generally constructed to see if REBOA is beneficial, especially in this time of rapid investigation. And it was performed by institutions who are using it regularly. This could introduce a significant degree of confirmation bias, since we all try to see what we already believe to be true (“REBOA is good”).

The authors are basing this “clear survival advantage” on overall mortality where only a few confounding factors have been controlled for. The GCS wild-card here is a perfect example. It could have considerably contributed to mortality in the open group, making it look bad. Who determined whether REBOA or open technique would be used, and why? This can have a major impact. What other factors might be present that are not even recorded in the database?

It is also stated that this increased survival was accomplished without increasing systemic complications. Perhaps, but that may be true of only the ones examined, or those recorded in the registry. Many may be missing. And what about the 10% incidence of limb issues in the REBOA group? This is a major problem and should not be glossed over. Although the patients that required a vascular repair were reported to do well, the others with ischemia or limb loss obviously did not.

Bottom line: Reading abstracts is like reading scientific papers, only more difficult because information is missing due to length limitations. Look at the title. Look at the conclusions. But don’t believe anything until you can understand every one of the results listed. And be sure to think about all the things that have to be left unsaid because of the size of the abstract! 

Having said all that, I still have to be careful that this doesn’t trigger my own confirmation bias. My take is that REBOA is still an investigational device. We need further comprehensive data to make sure that survival and safety are properly balanced.

Here are some questions for the presenter and authors:

  • The abstract describes the number of cases identified as 109; 84 REBOA and 25 open occlusions of the aorta. This seems to include patients undergoing CPR upon arrival, and these are excluded from some of the statistics. However, I can’t get the mortality percentages to match for the group that supposedly includes CPR patients. For example, the overall REBOA (includes CPR) mortality percentage is 35.17%. Multiplying this by 84 gives 29.5 patients. But multiplying the 33.33% mortality (CPR-excluded group) by 84 yields 28 patients. So are the 109 patients listed in the abstract the CPR-excluded group or not?
  • The open aortic occlusion group had a lower GCS. Did you look at how this might have contributed to the higher observed mortality? Although numbers are already low, is there any way to match for this to clarify the picture?
  • Do you have any information yet on longer term outcomes in the two groups? This will become very important as we come to balance raw survival with quality of life and complications.

Great abstract! I’m looking forward to the presentation, and hopefully more answers!

Reference: SURVIVAL BENEFIT FOR PELVIC TRAUMA PATIENTS UNDERGOING RESUSCITATIVE ENDOVASCULAR BALLOON OCCLUSION OF THE AORTA: RESULTS OF AAST, AORTIC OCCLUSION FOR RESUSCITATION IN TRAUMA AND ACUTE CARE SURGERY (AORTA) REGISTRY. AAST 2019 Oral Abstract #3.