All posts by TheTraumaPro

Validation Of The Air Medical Prehospital Triage Score (AMPT)

Unneeded use of helicopter emergency medical services (HEMS) air transport is a problem around the world. This scarce and valuable resource tends to be over-utilized, resulting in unnecessary costs to patients and the health care system in general. Unfortunately, good and objective criteria for HEMS transport have been hard to come by.

A group at the University of Pittsburgh published a study earlier this year, developing an objective scoring system based on a huge dataset from the National Trauma Databank. They used a portion of the data to develop a model, and the remainder to test it. They developed the AMPT, which identified patients that showed a survival benefit with helicopter transport:

AAST2016-Oral23

For this AAST abstract,  they sought to validate the scoring system using an entirely different database, the Pennsylvania Trauma Systems Foundation registry. They used 14 years of data, and reviewed nearly a quarter million records. Once again, the authors were looking at in-hospital survival.

Here are the factoids:

  • 20% of patients were transported by air
  • But only 11% were predicted to benefit by using AMPT
  • For patients with an AMPT score < 2, transport by air did not increase survival
  • For patients who had an AMPT score >and were actually transported by air, survival was improved by 31% (!)

Bottom line: It looks like the AMPT score is a good predictor of improved survival for patients transported by air. But wait, it’s not that cut and dried. These statistics are based on populations; they cannot predict exactly which individual patient will benefit. What about those patients who actually died? Perhaps if they had gotten to the hospital a little faster, they would have done better? This is certainly a nice new tool to use in the decision-making process, but it can’t be the only one. 

References:

  • The air medical prehospital triage score: external validation supports ability to identify injured patients that would benefit from helicopter transport. AAST 2016, Paper #23.
  • Development and validation of the air medical prehospital triage score for helicopter transport of trauma patients. Ann Surg 264(2):378-385, 2016.

Which ICU For Neurotrauma Patients: Neuro-, Trauma-, or Med/Surg?

Different hospitals have different arrangements for taking care of critically injured patients. All Level I or II trauma centers have at least a mixed med/surg ICU, with most level I centers having a dedicated surgical unit. A few have specific trauma or neuro-critical care ICUs.

In general, severely injured trauma patients do better when taken care of by trauma teams who have sufficient experience (volume). What about patients with severe traumatic brain injury (TBI)? Does the experience and volume of patients receiving care in the ICU make a difference?

A group of 12 trauma centers with varying ICU arrangements pooled their outcome data to see if the type of ICU makes a difference. All patients admitted with GCS<14 with CT evidence of TBI were evaluated if they were admitted to an ICU.

Here are the factoids:

  • 2951 patients from the 12 centers met inclusion criteria
  • Type of ICU, age, and ISS were independent predictors of death
  • Patients admitted to a trauma ICU had the best probability of survival, and stayed high across all ISS scores
  • Those admitted to med/surg ICUs had higher probabilities of death, especially with higher ISS (> 38 or so)
  • Survival for isolated TBI patients in a neuro ICU was similar to a trauma ICU in patients with lower ISS (< 32)

AAST2016-Oral21

Bottom line: This is a fascinating study, but it is giving us just a glimpse of the complete picture. What’s the difference between a med/surg ICU vs a trauma ICU. How much head trauma does a neuro ICU have to see? What kind of nurses work in them? What types of critical care physicians? 

These questions are not answered in the abstract. And they may not be answered during the presentation at the meeting. But they are extremely important, and must be resolved in the next iteration of this study. Hopefully, there will be one!

Reference: Neuro-, trauma-, or med/surg-ICU: does it matter where polytrauma patients with TBI are admitted? Secondary analysis of the AAST-MITC decompressive craniectomy study. AAST 2016, paper #21.

The Cardiac Box: Meaningful For Gunshot Wounds?

A common dogma in trauma training is: “Watch out for the box!” This area on the anterior chest is purported to indicate high risk of cardiac injury in patients with penetrating trauma.

Where is it, exactly? Technically, it’s the zone extending from nipple to nipple, and from sternal notch to xiphoid.

The cardiac box

But is the dogma true? A number of (old) papers mapped out the location and incidence of cardiac injury in stabs to the chest and upper abdomen. And there is a pretty good correlation. For stab wounds. But what about gunshots?

A team at Emory University ran a retrospective review of their trauma registry data over a three year period.

Here are the factoids:

  • They saw nearly 90 patients per year with penetrating chest wounds. Of these, 80% were gunshots (!) Many had more than one penetration.
  •  Of the 233 gunshots inside “the box”, 34% injured the heart
  • The remaining 44 gunshots outside “the box” hit the heart 32% of the time
  • The authors suggest shifting the definition of “the box” toward the left, so that it extends from anterior midline, wraps around the left chest, and ends in the posterior midline (see below)

new-cardiac-box

Bottom line: Here’s the problem. Knives are attached to a handle which tends to stay outside your patient. Thus, it can only go so deep. But a bullet will keep going until something stops it, or it runs out of gas. So it makes sense that the traditional boundaries of “the box” don’t apply. But extending it to include the left lateral chest and exclude everything on the right side? It may make statistical sense in this study, but common sense dictates that the trauma professional needs to think about the heart any time a gunshot goes anywhere near the chest or upper abdomen. Do not limit yourself to any “box!”

Reference: Redefining the cardiac box: evaluation of the relationship between thoracic gunshot wounds and cardiac injury. AAST 2016 Paper #12.

Battle of the Heparins: Unfractionated vs Low Molecular Weight

Most trauma programs tend toward using low molecular weight heparin (LMWH) products for VTE prophylaxis over plain, old-fashioned unfractionated heparin (UH). How did this happen? LMWH is more expensive than UH, and there is precious little high quality research supporting it.

But, LMWH is very convenient, as it only needs to be given only once or twice daily via subq injection, whereas UH is given as a continuous infusion or subq three times a day. And a fair amount of lower quality data suggests that it is effective in decreasing deep venous thrombosis (DVT) and pulmonary embolism (PE).

This abstract comes from Sunnybrook in Toronto. The authors used sophisticated statistical models to compare centers that predominantly use LMWH to prevent VTE vs those that use UH.

Here are the factoids:

  • This was a huge data analysis from the ACS Trauma Quality Improvement Program database (~ 110,000 records from 214 trauma centers)
  • LMWH was most commonly used, 74% of the time
  • Patients who were more likely to need rapid reversal were more often given UH (older patients, severe TBI, early intracranial interventions)
  • Pulmonary embolism was significantly lower with LMWH (1.8% vs 2.4%)
  • This significant effect was present across all subgroups, including patients with shock, blunt multisystem injury, penetrating trunk injury, isolated orthopedic injury, and severe TBI
  • Trauma centers that predominantly used LMWH had significantly lower PE rates compared to UH (1.2% vs 1.8%)

Bottom line: Even given the vagaries of using huge, retrospective database reviews, this is pretty good data. The use of LMWH appears to be superior to UH in reducing the incidence of pulmonary embolism. It does not prevent it completely. But it’s a good start.

What the authors do not say, and I am curious about, is the impact on DVT. That is a much more common problem than PE. Was there any difference? Did they run out of room to comment on it in the abstract? I kind of doubt it. The devil will be in the details. Listen in on the presentation at the meeting!

Reference: Efficacy of low molecular weight heparin vs unfractionated heparin to prevent pulmonary embolism following major trauma: results from the American College of Surgeons Trauma Quality Improvement Program. AAST 2016 Paper #5.

AAST 2016 Is Coming Soon!

The 75th annual meeting of the American Association for the Surgery of Trauma (AAST) is just around the corner. It’s being held on the big island of Hawaii, which pretty much guarantees a large turnout. Hard to resist a little vacation time tacked on to the meeting!

Starting tomorrow, there are 17 weekdays left until the end of the meeting. This year, there are a lot of interesting abstracts, and I’ll be posting info and my commentary about the best of the best (and maybe some worst of the worst?).

Here are some of the topics I’ll be covering:

  • Which is better for pulmonary embolism prevention: Unfractionated vs low molecular weight heparin?
  • The cardiac “box”
  • Which ICU is better for neurotrauma patients: neuro-ICU, trauma-ICU, or med/surg-ICU?
  • A scoring system for identifying appropriate patients for air transport
  • The Cribari Matrix and over/undertriage
  • Preperitoneal pelvic packing
  • Are graduating surgery residents qualified to take trauma call?
  • VTE prophylaxis in children
  • and about 9 more!!

Stay tuned starting tomorrow!