Tag Archives: pelvic fracture

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.

What’s The Best Pelvic Binder? Part 2

Yesterday, I detailed some pelvic binders commonly available in the US. Today, I’ll go through the (little) science there is regarding which are better than others.

There are a number of factors to consider when choosing one of these products. They are:

  • Does it work?
  • Does it hurt or cause skin damage?
  • Is it easy to use?
  • How much does it cost?

It’s difficult to determine how well binders work in the live, clinical setting. But biomechanical studies can serve as a surrogate to try to answer this question. One such cadaver study was carried out in the Netherlands a few years ago. They created one of three different fracture types in pelvis specimens. Special locator wires were placed initially so they could measure bone movement before and after binder placement. All three of the previously discussed commercial binders were used.

Here are the factoids:

  • In fracture patterns that were partially stable or unstable, all binders successfully closed the pelvic ring.
  • None of the binders caused adverse displacements of fracture fragments.
  • Pulling force to achieve complete reduction was lowest with the T-POD (40 Newtons) and highest with the SAM pelvic sling (120 Newtons). The SAM sling limits compression to 150 Newtons, which was more than adequate to close the pelvis.

So what about harm? A healthy volunteer study was used to test each binder for tissue pressure levels. The 80 volunteers were outfitted with a pressure sensing mat around their pelvis, and readings were taken with each binder in place.

Here are the additional factoids:

  • The tissue damage threshold was assumed to be 9.3 kPa sustained for more than 2-3 hours based on the 1994 paper cited below.
  • All binders exceeded the tissue damage threshold at the greater trochanters and sacrum while lying on a backboard. It was highest with the Pelvic Binder and lowest with the SAM sling.
  • Pressures over the trochanters decreased significantly after transfer to a hospital bed, but the Pelvic Binder pressures remained at the tissue damage level.
  • Pressures over the sacrum far exceeded the tissue damage pressure with all binders on a backboard and it remained at or above this level even after transfer to a bed. Once again, the Pelvic Binder pressures were higher. The other splints had similar pressures.

And finally, the price! Although your results may vary due to your buying power, the SAM sling is about $50-$70, the Pelvic Binder $140, and the T-POD $125.

Bottom line: The binder that performed the best (equivalent biomechanical testing, better tissue pressure profile) was the SAM sling. It also happens to be the least expensive, although it takes a little more elbow grease to apply. In my mind, that’s a winning combo. Plus, it’s narrow, which allows easy access to the abdomen and groins for procedures. But remember, whichever one you choose, get them off as soon as possible to avoid skin complications.

References:

  • Comparison of three different pelvic circumferential compression devices: a biomechanical cadaver study. JBJS 93:230-240, 2011.
  • Randomised clinical trial comparing pressure characteristics of pelvic circumferential compression devices in healthy volunteers. Injury 42:1020-1026, 2011.
  • Pressure sores. BMJ 309(6959):853-857, 1994.

What’s The Best Pelvic Binder? Part 1

Several products for compressing the fractured pelvis are available. They range from free and simple (a sheet), to a bit more complicated and expensive. How to decide which product to use? Today, I’ll discuss the four commonly used products. Tomorrow, I’ll look at the science.

First, let’s dispense with the sheet. Yes, it’s very cheap. But it’s not easy to use correctly, and more difficult to secure. Click here to see my post on its use.

There are three commercial products that are commonly used. First is the Pelvic Binder from the company of the same name (www.pelvicbinder.com). It consists of a relatively wide belt with a tensioning mechanism that attaches to the belt using velcro. One size fits all, so you may have to cut down the belt for smaller patients. Proper tension is gauged by being able to insert two fingers under the binder.

Next is the SAM Pelvic Sling from SAM Medical Products (http://www.sammedical.com). This device is a bit fancier, is slimmer, and the inside is more padded. It uses a belt mechanism to tighten and secure the sling. This mechanism automatically limits the amount of force applied to avoid problems with excessive compression. It comes in three sizes, and the standard size fits 98% of the population, they say.

Finally, there is the T-POD from Pyng Medical (http://www.pyng.com/products/t-podresponder). This one looks similar to the Pelvic Binder in terms of width and tensioning. It is also a cut to fit, one size fits all device. It has a pull tab that uses a pulley system to apply tension. Again, two fingers must be inserted to gauge proper tension.

So those are the choices. Tomorrow, I’ll go over some of the data and pricing so you can make intelligent choices about selecting the right device for you.

Complications Of Iliac Artery Embolization

The main cause of mortality in patients with severe pelvic fractures is major hemorrhage. Over the years, trauma professionals have developed and tested a number of maneuvers to reduce mortality in these patients. These include wrapping or fixing the pelvis, embolization, and more recently, pre-peritoneal packing and REBOA.

Pelvic wrap/fixation and embolization have been around for a long, long time. For both, it’s been long enough so that we should have a fairly decent appreciation of the complications. For pelvic binders, they principally involve the skin. But aside for the potential access site complications (bleeding, pseudoaneurysm), angiography has been thought to be relatively benign.

But as with any medical procedure, especially invasive ones, there are risks. A paper published five years ago retrospectively reviewed the 13 year experience with pelvic angiography at UC Davis. Study patients were matched with controls who underwent angiography for pelvic fracture but not embolization. Short-term (within 30 days) and long-term complications were assessed while in hospital and by telephone survey. Mean followup time was 18 months.

Here are the factoids:

  • There were no differences in complications attributable to embolization within 30 days of the procedure
  • There were 5 cases of short-term skin sloughing or necrosis in 55 patients, and 4 of 5 occurred in patients with nonselective embolization. However, this was not a statistically significant complication.
  • Long-term complications such as buttock claudication or skin ulceration, pain, and impotence were not significantly different in embolized vs non-embolized patients
  • There was a significantly increased incidence of buttock, perineal, or thigh paresthesias in the long-term

Bottom line: Angiography with embolization is a very valuable tool in the management of complication pelvic fractures. Remember that a number of complications have been described:

  • Skin sloughing or necrosis
  • Buttock claudication, pain, paresthesias
  • Skin ulceration
  • Impotence

Other than an increase in paresthesias in the long-term, there did not appear that there was any difference in patients undergoing angiography with and without embolization. Although the numbers were small (100 patients total), this is the best study we have to date. Just keep in mind that complications are possible, and question your patients about them when they present for their followup visits.

Reference: Evaluation of Short-term and Long-term Complications after Emergent Internal Iliac Artery Embolization in Patients with Pelvic Trauma. J Vascular Interventional Rad 19(6):840-847, 2008.

Early Operative Fixation of Pelvic Fractures And Functional Outcome

Disruption of the pelvic bones takes a huge amount of energy, and results in significant bleeding and morbidity from other causes. Repair typically consists of surgical fixation, frequently with temporary external fixation in the interim. These patients require intensive therapy postoperatively, with inpatient rehab prior to discharge home.

How well do patients with severe pelvic fractures do in the longer term? The group at the University of Tennessee in Memphis did a lengthy followup study spanning 18 years of severe pelvic fractures treated at their hospital. These patients had sustained fractures with significant bleeding, an open book component, or SI joint disruption with vertical shear.

open book pelvis pre

The authors used phone interviews and a standardized measurement instrument (Activity Measure for Post-Acute Care, AM-PAC) to gauge daily activity of affected patients. They then looked for factors predictive of functional outcome.

Here are the factoids:

  • 401 patients were identified over the 18 year study period
  • Of these only 71% survived (285), and the study documented followup in 145 (51%)
  • Average ISS was 27 (fairly high) and patients tended to be older (mean 53 years)
  • Even after 8 to 20 years, mobility and activity were significantly impaired as measured by AM-PAC
  • Time to fixation was the only identifiable factor that had an impact on decreased mobility or activity

Bottom line: Early definitive fixation of the pelvis was the only variable found that had an impact on future mobility and activity. Frequently, external fixation is applied soon after admission. But remember, your trauma patient is at their healthiest as they roll through the doors of your ED. The sooner they get all of their problems fixed, the better (and safer).

Impact of early operative pelvic fixation on long-term functional outcome following sever pelvic fracture. AAST 2016, Paper 60.