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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.

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!

Procedures

ED Thoracotomy: Kids ARE Just Small Adults

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You’ve undoubtedly read this trite phrase somewhere in your training: “Kids aren’t just small adults!” There are many examples where this is absolutely true. Think about arterial extravasation in solid organ injury. Or severe traumatic brain injury. There are major differences in treatment aggressiveness for both of these.

But what about the code situation? I’ve noted a peculiar phenomenon over the years with regard to pediatric codes of all kinds. Adults tend to persist far longer at resuscitative efforts over children than they normally would on other adults. And what about that most extreme code situation, the emergency thoracotomy?

I’ve also seen the use of this procedure in children who don’t meet the usual adult criteria. But they are kids, right? They can bounce back from more severe insults, right? I hope that I’ve convinced you over the years that one can’t just assume and generalize anything. Things that seem like so much common sense often turn out to be wrong. Think back to the days of the stress / spicy food theory of peptic ulcer disease. This seems so silly now that we recognize the role of H. Pylorii.

Scripps Mercy adult and Rady Children’s Hospital pediatric trauma centers in San Diego performed an extensive review of the National Trauma Data Bank over a three year period. They focused on patients 16 years of age or less who underwent ED thoracotomy within 30 minutes of arrival at the trauma center. They focused on procedure indications and the eventual outcomes.

Here are the factoids:

  • A total of 114 patients were recorded in the NTDB, with a mean age of 10 years and median Injury Severity Score of 26 (this is the three year experience in the entire US in three years!)
  • Males were disproportionately involved at 69%, although this is less than in adults
  • Thoracotomy was performed promptly, with a median time after arrival of 5 minutes
  • Mechanism of injury was almost evenly split between penetrating (56%) and blunt (44%)
  • Blunt mechanism mortality was 94% vs 88% for penetrating
  • Penetrating injury outside of the thorax was uniformly fatal
  • Patients without signs of life on arrival, regardless of mechanism, also had a 100% mortality rate
  • Treatment at an adult trauma center, freestanding pediatric center, or combined center had no impact on these dismal outcomes

Bottom line: This is an interesting paper, and shows that the outcomes after ED thoracotomy in kids is even more dismal than in adults. This is particularly true for children arriving without vital signs and for penetrating abdominal trauma.

However, the authors go on to suggest a practice guideline for pediatric emergency thoracotomy similar to the EAST adult guidelines based on their study findings. However, I think this is ill advised. Have a look at the absolute numbers:

The largest subgroup has only 29 patients in it. These numbers are way too small to consider a guidelines change.

This paper shows that kids are just small adults when it comes to ED thoracotomy. And they seem to do even more poorly with no vital signs or penetrating injuries outside of the chest. So think carefully the next time you must consider this procedure in a child.

Reference: Nationwide Analysis of Resuscitative Thoracotomy in Pediatric Trauma Time to Differentiate from Adult Guidelines? J Trauma published ahead of print, July 6, 2020.

 

What the heck?

Nail In The Neck: A Novel Removal Option

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Here’s a post from my archive describing a different way to remove the foreign body. This is the technique I used, instead of the standard neck incision. The final incision was just a slight extension of the puncture wound, measuring only 1cm. I was able to grasp the head and pull it out without difficulty. The surprising thing to me was the amount of force I needed to apply to actually pull it out! No bleeding, no problems. The patient was observed for 24 hours and discharged home. He had no complications.

A Cool Way To Remove Embedded Foreign Bodies

Many of us have had the experience of digging into bloody tissue for long periods of time trying to locate the object, even with fluoroscopy. Well, there’s a better way of doing this.

A group in China described a technique using a fancy form of needle localization. They employed a set of instruments normally used for lumbar diskectomy (see photo). This set includes a long 18 Ga needle with a removable hub, several dilators and an outer cannula with a 5.8mm diameter. A pair of 3.8mm grasping forceps is also used.

The foreign body is located using a C-arm fluoroscopy unit and the best approach is planned. The 18 Ga needle is then inserted using fluoro until it touches the object. The hub is removed and dilators are inserted over the needle, one after the other. The outer cannula is then placed over them, and the needle and dilators are then removed. The cannula is manipulated until the foreign body (or a part of it) is located within the cannula. It is then grasped and removed, along with the cannula if needed. If the object is too large to enter the cannula, the cannula is pulled back slightly and the grasper introduced past the end of it to grip and remove the foreign body.

The writers shared the details of 76 patients who had a total of 251 foreign bodies removed over a 6 year period. The depth varied from 2.5 to 8.5cm. Procedure time ranged from 8 to 15 minutes, and fluoro exposure varied from 1 to 4 minutes. Success rate was 100% (all foreign bodies were removed) and there were no complications.

Bottom line: This is a very slick technique that promises to dramatically increase the success rate and decrease complications from removing foreign bodies. The amount of time spent is much less than the brute force technique, as is the amount of soft tissue trauma. Large objects that cannot be grasped with these forceps cannot be removed with this method. Although I am a little concerned that the authors’ results were so perfect, it’s certainly worth a try!

Reference: Percutaneous extraction of deeply-embedded radiopaque foreign bodies using a less-invasive technique under image guidance. J Trauma 72(1):302-305, 2012.

What the heck?

Nail In The Neck: The Operation

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We’ve made sure that our victim of the nail gun to the neck did not need an emergent operation. Vitals are stable, there’s no uncontrolled hemorrhage, and the patient is neurologically intact. We’ve imaged him using CT angiography, and the nail does not appear to have injured any vital structures.

How do we get it out of there? There are two things that need to be considered: where and how.

Rule of thumb: If a foreign body is located anywhere near vital structures, take it out in the OR, no matter how good you think the imaging is. It may be tempting to just pull it out in the ED, but resist! CT scans look so good, and they are so detailed, but they are not perfect. The ED does not have the equipment, personnel, or lighting necessary if something goes awry.

Rule of thumb: Use all information available to plan the removal procedure. In this case, the head of the nail is to the patient’s right. Therefore, it must be removed from the right side. The CT shows that the nail passes very close to the posterior pharynx, so it will need to be evaluated during the procedure.

This patient was taken to the operating room. During the intubation, direct laryngoscopy was carried out to carefully inspect the entire pharynx and larynx. No evidence of penetration was seen. The entire neck, face, and upper chest were prepped and draped (I like to go overboard in trauma cases; you never know what is going to happen). Fluoroscopy was available.

The classic operation would have been to make an incision along the sternocleidomastoid on the right side. The nail head would be approached directly. Since long, thin objects can be notoriously difficult to locate, fluoro can be very helpful. The exact position with respect to the carotid and jugular can be ascertained. Then the nail head is grasped with a clamp, and the nail gently pulled out along its axis. A nice, long wait for any evidence of bleeding should occur. The area can then be irrigated and the incision closed. Skin antibiotics can be given postop, but only one dose at most.

Having said that, I opted for a different approach based on an old blog post here. Tune in on Wednesday to see what I really did.