Tag Archives: REBOA

Abdomen, Abstracts

Best Of AAST #2: REBOA And Unstable Pelvic Fractures

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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.

Abstracts, Resuscitation

AAST 2019 #1: Survival Benefit Of Pelvic REBOA

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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.

Technology

Best of AAST #7: What’s New With Reboa

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Despite all you read about it these days, REBOA is still very new. The first papers describing use in humans are barely 5 years old! A few select centers have been early adopters and are publishing a regular flow of research on their experience.

But we need more numbers! Many trauma centers have considered, or actually adopted the use of REBOA already. However, we are still working out a lot of the nuts and bolts of this very invasive procedure. The group at University of Arizona – Tucson reviewed the national experience over a two year period by massaging the data in the Trauma Quality Improvement Program (TQIP) database. All Level I-III trauma centers in the US are required to report their experience to this large, detailed collection of trauma data.

They performed a retrospective review of REBOA vs non-REBOA patients matched for demographics, prehospital and emergency department vital signs, mechanism of injury, degree of pelvic disruption in pelvic fracture patients, solid organ injuries, and lower extremity fractures and vascular injuries. The studied outcomes were complications and mortality.

Here are the factoids:

  • Nearly 600,000 records were scanned for the two year period, and only 140 REBOA patients were identified (!)
  • These 140 REBOA patients were matched with 280 similar non-REBOA patients
  • Average age was 44 and average ISS was 29, 74% were males and 92% were blunt trauma
  • Overall complication rate was 7.4% and mortality was 25%
  • There was no difference in 4-hour or 24-hour numbers of blood, plasma, or platelets transfused
  • ICU and hospital length of stay were identical
  • 24-hour mortality in the REBOA group was significantly higher (36% vs 19%)
  • REBOA patients were significantly more likely to require amputation (5% vs 1%)

Bottom line: These are not great numbers for REBOA! What gives? There are a number of possibilities:

  • It’s a database study, so some key information might be missing
  • The numbers remain small, only 140 patients out of half a million records in two years!
  • There is no way to know how the patients were selected for REBOA
  • The experience and skill level at the hospital performing the procedure is not known
  • The interplay of other injuries and comorbidities is unclear
  • And many more…

BUT, the numbers are concerning. The early adopter centers have better outcomes, and this has prompted many centers with fewer eligible patients to jump on the bandwagon. We all need to remember that this is a brand new procedure and we are still learning the nuances. It is extremely important that every center performing REBOA contribute their results to a national registry. We still need to figure out which patients will benefit from it, how it should be used, and how we can minimize complications and maximize survival in our patients.

Reference: Nationwide analysis of resuscitative endovascular balloon occlusion of the aorta (REBOA) in civilian trauma. Session I Paper 5, AAST 2018.

Procedures

REBOA At An Academic Trauma Center

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Resuscitative endovascular balloon occlusion of the aorta (REBOA) is the big thing these days. I’ve written about this topic in the past, and a number of centers continue to refine our understanding of this new(er) tool.  A recent paper from the University of Florida – Gainesville outlines their experience in implementing this procedure at an academic Level I trauma center.

This trauma program is staffed by a group of surgeons who have considerable experience in guidewire-based skills, fellowship or military exposure, and/or completion of a vascular fellowship. One surgeon attended a trauma endovascular skills course (6 hrs).  An internal education program with a 1.5 hour slide presentation and some hands-on simulation training was developed. All surgeons and residents completed this program.

A retrospective review of their experience from June 2015 to March 2017 was carried out on unstable trauma patients due to hemorrhage. All cases were performed in a hybrid OR with imaging capabilities. A 12Fr REBOA catheter was initially used, but was changed to 7Fr once that catheter became commercially available.

Here are the factoids:

  • 16 patients underwent REBOA in this 22 month period; mean SBP was 97 torr and mean ISS was 39
  • Hemodynamic status improved in 10 of 16 patients to a mean SBP 132
  • 14 survived the initial operative procedure, but only 6 survived to hospital day 30. It appears that all of these patients were neurologically normal (GCS 15+0).
  • 1 survivor developed a common femoral artery pseudoaneurysm
  • The authors made the interesting comment that they also performed 8 ED thoracotomies (EDT) during this period and that there were no survivors
  • The authors concluded that the procedure was beneficial, that extensive training was not needed, and that it should be available trauma centers

Bottom line: But not so fast! This was a very select academic Level I center. The surgeons had extensive wire skills and vascular experience. All procedures were performed in a hybrid room, which is a very controlled OR setting. And they only performed REBOA every 6 weeks or so. 

REBOA is still an advanced procedure, and the average trauma surgeon would probably benefit from some more intensive training to ensure adequate initial skills. But if the surgeon can’t then maintain their skills via somewhat regular practice, errors may creep in. In a group of 6-8 surgeons, each may only get to perform the procedure once a year! Add in some interested emergency physicians, and no one can keep in practice.

The bit about ED thoracotomy is a bit of a red herring. Typically, this procedure is performed once the patient has lost their vital signs. Comparing mortality from REBOA with EDT here is not valid, because it appears that most of the REBOA patients in this study still had vital signs when it was inserted. It would be interesting if the authors shared the outcomes in the REBOA patients who had the device inserted after arrest to level the playing field with EDT.

So what to do? Be cautious and thorough if you are planning to try out REBOA at your center. Do the math. On how many patients per year can I expect to perform this? How many physicians want credentialing to do it? How many procedures can the typical physician expect per year? What is the baseline level of physician training and what additional training is needed? Will I report my experience to a national registry or write it up for sharing?

These are important questions! Everyone wants to play with the newest shiny toy in the toybox. But make sure that when you do play with it, you are able to provide the maximum benefit to your patients with the least amount of harm!

General

ACS Trauma Abstracts #1: REBOA! (And CT???)

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This paper is from the group at ShockTrauma in Baltimore, who are really pushing the envelope of REBOA. We always worry about distal ischemia after balloon inflation, because the ischemia produced can be detrimental to the gut and lower extremities. This group was curious about what the flow patterns looked like with  inflation of the balloon. So in select cases, they obtained CT scans with contrast in patients while the balloon was fully inflated (!!).

They reviewed their experience over a four year period, looking at patients receiving a CT scan with the REBOA balloon partially or fully inflated.

Here are the factoids:

  • Nine patients were included. This makes sense because unstable patients should not go to CT scan, so this should be a very limited group.
  • Mean injury severity score (ISS) was 48, which makes sense. These patients are hurt bad!
  • Four patients had supraceliac REBOA (aortic zone I) and five had infrarenal (zone III)
  • Contrast was seen below the REBOA balloon in all patients, and was seen distal to the insertion site in half
  • Collateral flow around the balloon was identified in all patients

Bottom line: The authors found that REBOA decreased blood flow to the distal aorta, but certainly did not stop it. Collateral flow is underestimated, and probably provides a protective effect for the viscera and other structures while inflated. This is good news for REBOA proponents, because it suggests that placement may not cause as much risk from ischemia as originally thought.

But why oh why did they have to go to  CT in the first place?

Reference: Assessment of blood flow patterns distal to aortic occlusion (AO) using computed tomography in patients with resuscitative endovascular balloon occlusion of the aorta. JACS 225(4S1):S50, 2017.