Tag Archives: HEMS

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.

Are We Wasting Valuable Helicopter EMS Resources?

The use of helicopters for transporting injured patients dates back to World War II. Thirty years later, this concept was translated into civilian practice. Today, there are hundreds of helicopter EMS (HEMS) services across the US, and thousands world-wide. Unfortunately, the indications for using this service are not strictly defined, and it is very expensive compared to ground EMS transport. In the US alone, there are over 400,000 HEMS transports per year. This creates the opportunity for use in patients who are not seriously injured, as well as the potential for wasted resources.

The University of Arizona at Tucson examined 6 years of transport data to their center, by both ground and air. They were interested to see if they could identify a group of HEMS-transported patients that could have safely and more reasonably been transported by ground ambulance. They defined this group of “minimally injured” as having an injury severity score (ISS) of 5 or less.

Here are the factoids:

  • A total of 5,202 patients were transported, 19% by air and 77% by ground
  • Overall, the hospital length of stay was significantly longer for HEMS patients (3 vs 2 days), as was ICU length of stay (2 vs 1 days) [Hmm..]
  • ISS was significantly higher in the HEMS group as well (9 vs 5) [Hmmmmm…]
  • There was [of course] no difference in mortality between the two groups
  • By their definition, 28% of HEMS patients were minimally injured, compared to 39% of ground transfers
  • The average charge for a HEMS transport was $18,000

Bottom line: This is another paper that just doesn’t deliver on what it’s title suggests. But this one is an underestimation of the result, not an overestimation, for once. From personal experience, I see lots of examples of patients who don’t need air transport but get it anyway. But if you dive more deeply into the data in this paper, you can see why it’s just not good enough. Sure, they’ve got a lot of patients. But if you look at the clinical reality of the numbers, none of the patients were really that sick. The maximum ISS in the HEMS group was 17! The GCS for every patient in the study was 14 or 15. The maximum hospital LOS was 7 days. And the clinical significance of a 3 day vs a 2 day hospital stay is negligible.

These were just not very sick patients. It looks to me like none of their patients needed HEMS transport, other than for extreme distance issues. The authors needed to set a better definition of minimally injured patients, and if they had, they would have found that most of their HEMS transfers could have been shifted to ground ambulance.

This paper really points out (more than the authors anticipated) the potential resources being wasted. There are already some suggested rules for optimal use of HEMS. But unfortunately, we tend to ignore them! It’s time to start a concerted effort to more wisely use this valuable and expensive resource.

Related posts:

Reference: Overuse of helicopter transport in the minimally injured: a health care system problem that should be corrected. J Trauma 78(3): 510-515, 2015.