Category Archives: Abstracts

Abdomen, Abstracts

Best Of AAST #3: Nonoperative Pancreatic Injury Management In Children

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Over the years, the operative vs nonoperative management pendulum has swung to and fro. For solid organ injuries, operative management was routine until about 30 years ago. Since then, it has moved to the opposite end of the spectrum.

Similar swings have occurred in pediatric trauma management as well. Most notably it now involves that most dreaded of organs, the pancreas. In adults, this remains a problem for the operating room. But for the past 6-8 years, pediatric trauma surgeons have been dabbling with “conservative” management of pancreatic injuries.

The group at Baylor designed a prospective, multicenter study of seven pediatric trauma centers over a 2 year period. They specifically reviewed children with pancreatic injury with duct disruption (grade III). The injuries needed to be reasonably “fresh” (48 hours). They managed these children with a “Less is More” practice guideline that included early oral feeding, limited imaging and labs, and discharge based on improved symptoms. They compared their results to a previous multicenter trial performed 3-5 years earlier, before guideline implementation.

Here are the factoids:

  • There were 11 patients enrolled (!!) with a median age of 7 years
  • Clear liquids were started an average of 3.5 days postop, and a low fat diet at 6.7 days. Three patients (27%) failed to advance, requiring TPN.
  • ERCP stent was placed in 3 patients (27%)
  • Mean length of stay was 10 days
  • The authors pointed out that these numbers were all better than their published study prior to the “Less is More” guideline

Here are my comments: Unfortunately, I remember back to the days when any pancreatic injury with a duct injury, adult or child, went to surgery. For the usual, run of the mill tail transections from a handlebar injury, a quick tail resection was in order. The kids did well and were generally out of the hospital quickly (3-5 days) with few complications. I’ve operated on a handful of them, and this has been my (anecdotal) experience as well.

My concern is that, in this study, less (defined as nonop management) leads to more time to full diet, more collections and pseudocysts, and more time in the hospital.

In order to determine this, we need to know exactly how injured these 11 children were, details of their pancreatic injury, and a great deal about the data from the earlier study.  And I would be very surprised if there is sufficient statistical power to show a true difference based on only 11 patients.

Here are my questions for the authors and presenter:

  • Could some of the observed differences be due to varying grades of pancreatic injury? The abstract does not divide the kids by grade, so it is possible that some are grade III, some IV, and some are V. This makes it very difficult to tease reliable conclusions from this very small number of subjects (11).
  • Did they have other injuries as well that may have contributed to their slow recovery?
  • Have you compared your results to older research that analyzed these same variables for pediatric patients who were treated with pancreatic resection + drainage? Be prepared to compare your data to older studies, as well as to explain the details of your own historical study cited in the abstract.
  • It seems that trauma surgeons are becoming more reluctant to operate on kids. But for this injury, is that wise? Yes, the kid ends up with a scar on his abdomen. And may be missing his spleen. But what is the emotional trauma from having a tube stuck in your nose, a drain stuck in your side, or spending two weeks in the hospital? And maybe coming back for more touch-ups? Is this really better then a short one-time stay in the hospital.

There will be a lot of interest in your paper at the meeting. I can’t wait to hear you present it live!

Reference: Outcomes of standardized non-operative management of high-grade pnacreatic trauma in chilren: a study from the Pediatric Trauma Society Pancreatic Trauma Study Group. AAST 2020 Oral Abstract #6.

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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.

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Abstracts, Resuscitation

Best of AAST #1: What Has The MTP Bought Us?

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Let’s kick off my reviews of AAST 2020 abstracts with a paper on the results of recent advances in hemorrhage control. Over the past 10+ years we have seen the following new (and old) tools move into more widespread use:

  • Massive transfusion protocol (MTP) with a goal of 1:1 ratios of red cells to plasma
  • Availability of liquid plasma for more rapid use in the MTP
  • Addition of tranexamic acid (TXA) to resuscitation
  • Resurgence of tourniquet use by prehospital providers
  • Adoption of REBOA and TEG
  • Transfusion with whole blood

The authors analyzed their experience after serially introducing these tools to their resuscitation strategies, and studied their impact on overall mortality.

They retrospectively reviewed the experience over a 12 year period at their large Level I trauma center. Here are the factoids:

  • The reviewed a total of 824 MTP events. To put this into perspective from a volume standpoint, this is a little over one MTP activation per week.
  • Patients were primarily young (median age 31), male (81%), with a penetrating mechanism (68%). Median ISS was 25
  • Prehospital times were significantly longer at the end of the study, but the authors state that there was no correlation with an increase in in-hospital mortality
  • During the entire study, overall mortality ranged from 38% to 57%, and logistic regression did not identify an effect from any of the interventions

The authors concluded that their mortality rates have not improved despite all of the advancements we have added over the past decade. They suggest that future efforts should attempt to move targeted hemorrhage control backwards in time, out of the ED and toward to injury scene.

Here are my comments: This is an interesting and simple-appearing study. Overall, the authors didn’t really show that any of our “modern” resuscitation interventions did much for their patients at all.  There was a suggestion that tourniquet implementation and use of whole blood tended toward improving things.

But don’t be fooled by simplicity. There are many, many factors that enter into whether an individual patient lives or dies. When you fail to see a significant result in a study, first look at the methods and tools used for measurement. Are they powerful enough to discern changes? Do they cover enough of the factors that promote survival, not just our resuscitative advances? Or is the tool looking at the wrong things?

One big difference at this center is the sheer volume of penetrating trauma. This could have a major impact on survival, and may be very different from the experience of most centers that have predominantly blunt injury mechanisms.

And some questions for the authors:

  • What exactly is your definition of mortality? Made it out of the ED? Lived twenty four hours? Thirty days? This makes a big difference in how you look at the results.
  • Since you have only about one MTP event per week, do you think your numbers are large enough to actually detect a mortality difference? 
  • Did you consider looking at your unexpected survivors to see if there were any common threads in their care that might have made the difference? Maybe some of our resuscitative advances do make a difference, but only in specific subsets of patients.
  • Can you speculate about the reasons for longer prehospital times, and the impact on mortality?
  • How would you recommend pushing hemorrhage control back toward the scene? New tools for prehospital providers? More advanced providers in the rigs? This is an intriguing concept and it would be interesting to hear your thoughts.

This is a thought provoking paper that questions our assumptions about our time-honored resuscitation tools. I look forward to hearing it live next month!

Reference: After 800 MTP events, mortality due to hemorrhagic shock remains higha nd unchanged despite several hemorrhage control advancements; is it time to move the pendulum? AAST 2020 Oral Abstract #1.

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Abstracts

The Best Of The AAST 2020

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The 79th Annual Meeting of the American Association for the Surgery of Trauma starts in just three weeks! As usual, I will select a number interesting abstracts from the bunch to review. I’ll go over the findings of the research, critique it, and then provide a series of questions for the presenter to consider. These questions are ones that members of the audience may very well ask (hint, hint).

And FYI, I always send a heads-up to the presenters with a link to the post so they can study up beforehand!

I’ll begin posting my commentary on the best abstracts on a daily basis, starting tomorrow. And if you see things in them that you think I have missed the mark on, please feel free to comment!

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Abstracts

Best Of EAST #10: MTP With Whole Blood

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Here’s one last abstract to consider before the EAST meeting kicks off this afternoon. Every trauma center must have a massive transfusion protocol (MTP). But not every one has access to whole blood. And whole blood is all the rage now for transfusion in the trauma world.

Believe it or not, we must still ask the question “is using whole blood safe?” More than 50 years ago, all we had was whole blood. But we didn’t use it in trauma the way we do today. And we didn’t have the tools then to determine whether there were any adverse effects from its use. Now we do, and we are slowly rediscovering the nuances of using it. Some work has shown that small volumes of whole blood appear to be safe. But there is little information on the safety of using large volumes in MTP.

The group at Oregon Health Sciences University in Portland attempted to do this with a quick shot paper to be presented tomorrow morning. They reviewed their experience over a two year period. For the first 18 months, they used standard component therapy (PRBC + plasma + platelets) in their MTP. For the final six months, they used cold-stored uncrossmatched, low-titer group O blood. Any patient who had MTP activated and received even a single unit of blood was included in the study. 

Here are the factoids:

  • 83 patients received component therapy and 42 received whole blood; demographics were the same
  • The component therapy patients received an average of 6 PRBC, 5 plasma, and 0 platelets; the whole blood group received 6.5 units (4 PRBC, 4 plasma, and 1 platelets based on the usual composition of a unit)
  • Plasma:RBC ratio was 0.8:1 for the component group and 0.94:1 in the whole blood group (statistically significant, but not clinically significant, see below)
  • The authors described a component-equivalent unit of product which is not defined. It was 12 for component therapy and 27 for whole blood.
  • There were no differences in 24-hour or 30-day mortality, and no transfusion reactions

The authors concluded that MTP using whole blood is feasible, and that it appeared to be safe and effective. They also commented that it may lead to more balanced resuscitation.

My comment: Alright, this is the last time I’ll mention study power (for a while). If a study does not have the statistical power to show a difference between groups, then seeing no difference means nothing. The absence of a difference does not mean that the two groups are equivalent. And this study of 125 patients is small potatoes for showing any difference in a crude outcome like mortality.

Besides having a small number of subjects, the average number of units given was low for an MTP. For most trauma centers, this was just over one cooler of products. Although ISS was 29, the patients don’t sound like they had huge blood replacement requirements, so it’s no wonder that mortality was the same between the two groups.

And finally, the statement about more balanced resuscitation is open to debate. The difference between 0.8 units of plasma and 0.94 units is 35cc per unit of red cells given, a little over 1 tablespoon. It’s hard to believe that this would ever make a difference clinically.

To those who read only the title or the conclusion of an abstract (or paper for that matter), beware. The devil is in the details. This study is a good start toward addressing the question posed, but needs several hundred more subjects (and a lot more blood products given) to close in on an answer.

Reference: Massive transfusion with whole blood is safe compared to component therapy. EAST Annual Assembly Quick Shot #8, 2020.

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