All posts by TheTraumaPro

(Mis)Use of Helicopter Transport For Pediatric Trauma

Helicopter transport is an integral and important part of modern day trauma care. Since the inception helicopter emergency medical services (HEMS) for civilian use in the 1970’s, its use has been steadily increasing. And it’s expensive, at least five times more costly than ground transport. Plus, there are risks to both crew and patient, in that there have been 200 deaths of both patients and flight crews. Indeed, flight crews have one of the riskiest jobs, with 5 times more on-the-job deaths than police officers.

So it becomes very important to make sure that this mode of transport is justified. As I wrote previously, the adult HEMS literature is extensive, but not terribly convincing. There is far less data available regarding pediatric patients. And the data that does exist suggests that there may be significant overtriage and overuse.

A study using the National Trauma Data Bank (NTDB) was performed by researchers at Duke University. They reviewed the data for a 5 year period (2007-2011), which is fairly old in my opinion. And they included “children” up through age 18, which are also a bit old, in my opinion. Since there are no real quantitative criteria for overtriage in place, the authors picked three: low injury severity (ISS<10), normal physiology (RTS=12), and low predicted mortality using TRISS (<5%). A total of 127,489 patient records were analyzed.

Here are the factoids:

  • 14% arrived via helicopter EMS,  56% by ground EMS, and 29% by private vehicle or walk-in
  • HEMS patients were more likely to have head, thoracic, or abdominal injuries, and overall severe injuries (good!)
  • Adjusted mortality for patients transported by air was significantly less than for ground (really good)
  • 38% of HEMS patients had ISS < 9, and 66% had completely normal physiology (bad)
  • Overall, 32% to 82% of children did not meet criteria for appropriate transport

Bottom line: There are a number of flaws in this study that could be improved upon. However, it does provide some interesting data. Helicopter transport does save lives in the younger population, and was estimated at 2 per 100 flights. This is very promising. However, offsetting this was the fact that nearly half of transports failed one or more arbitrary appropriateness criteria. The recommendations I published yesterday need to be adopted, and both state trauma systems and local EMS agencies need to develop and enforce guidelines to optimally use this valuable and expensive resource.

Reference: Current use and outcomes of helicopter transport in pediatric trauma: a review of 18,291 transports. J Ped Surg in press 27 Oct 2016.

Helicopter EMS: The Recommendations

So after two days of pros and cons about helicopter EMS (HEMS), we lead up to this. The American College of Surgeons Committee on Trauma, Emergency Medical System subcommittee, has released a set of guidelines on appropriate use of HEMS. It’s been endorsed by the National Association of EMS Physicians and looks like a lot of thought has gone into it.

Here are the factoids about the HEMS guidelines:

  • Must be integrated with your trauma system
  • Must utilize standardized field triage guidelines that should be applied consistently throughout your trauma system
  • Is blind to the insurance status of the patient
  • Uses a regional dispatch system. Self-launch should never happen.
  • Referring physician to receiving physician conversations must occur when considering transportation mode (air vs ground) for interfacility transfers
  • There must be good online medical direction from a physician
  • Offline medical direction must be based on protocols and policies developed by the trauma system
  • There must be regular PI review of all HEMS transports to ensure compliance
  • HEMS crews must have regular training opportunities
  • A culture of safety must be maintained

Bottom line: We absolutely must take a critical look at our patient transport practices and procedures. To ensure even-handed application of best practices, our state trauma systems are going to have to step up and address this issue so the right patient will get to the right hospital at the right time, safely and cost effectively.

Reference: Appropriate use of Helicopter Emergency Medical Services for transport of trauma patients: Guidelines from the Emergency Medical System Subcommittee, Committee on Trauma, American College of Surgeons. J Trauma 75(4):734-741, 2013.

Helicopter EMS: The Risks

Yesterday, I wrote about the (unclear) benefits of helicopter EMS transports. Today, I’ll cover the risks. The number of medical helicopters in the US has grown dramatically since 2002.

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As can be expected, the number of mishaps should go up as well.

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Although it looks like the fatal and injury accidents peaked and then declined, it does not look as good when compared to the rest of the aviation industry. Consequently, being on a helicopter EMS (HEMS) crew has become one of the more dangerous professions.

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And unfortunately, the numbers have not improved much during the past five years. So what to do? Make it a big PI project. Approach it systematically, analyze the issues, and create some guidelines and protocols for all to follow.

Tomorrow, I’ll review  guidelines for HEMS released by the American College of Surgeons Committee on Trauma.

Reference: Medical helicopter accidents in the United States: a 10 year review. J Trauma 56:1325-1329, 2004.

Helicopter EMS (HEMS): The Benefits?

I’m going to kick off 4 days of information on helicopter emergency medical services (HEMS).

The use of medical helicopters has grown at an astonishing rate in the 10+ years since Medicare got involved with payment for this service. All high level trauma centers have helicopter landing facilities, and many either own or are a part owner in at least one helicopter EMS service (HEMS).

Here’s a state by state breakdown of the number of medical helicopters:

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It’s gotten to the point where the indication for summoning a HEMS service seems to be the presence of a patient to ride on it! 

A lot of papers have been published in the past 20 years trying to justify the benefits of using these services. As is the usually case when a lot of papers are published on one subject, most of them are not very good. Many studies have been performed to try to justify their use, and most were not successful. The following items have been scrutinized:

  • Interfacility transfers
  • Trauma
  • Pediatric transfers
  • Pediatric trauma
  • Burns
  • OB
  • Neonatal
  • Rural trauma

Most of these papers found little, if any, benefit. The ones that did tended to be published by institutions that owned these services, raising the significant question of bias. The one thing that was always significantly different was the cost. HEMS costs at least 5-10 times more than ground EMS transport.

So the benefits are not very clear. What about the risks? I’ll talk about those in my next post.

Click here to view the interactive state map of medical helicopters. See where your state is with respect to number of ships and services, and how busy they are.

Closing Velocity And Injury Severity

Trauma professionals, both prehospital and in trauma centers, make a big deal about “closing velocity” when describing motor vehicle crashes.  How important is this?

So let me give you a little quiz to illustrate the concept:

Two cars, of the same make and model, are both traveling on a two lane highway at 60 mph in opposite directions. Car A crosses the midline and strikes Car B head-on. This is the same as:

  1. Car A striking a wall at 120 mph
  2. Car B striking a wall at 60 mph
  3. Car A striking a wall at 30 mph

2010-saab-9-5-head-on-crash-test_100313384_m1

The closing velocity is calculated by adding the head-on components of both vehicles. Since the cars struck each other exactly head-on, this would be 60+60 = 120 mph. If the impact is angled there is a little trigonometry involved, which I will avoid in this example. And if there is a large difference in mass between the vehicles, there are some other calculation nuances as well.

So a closing velocity of 120 mph means that the injuries are worse than what you would expect from a car traveling at 60 mph, right?

Wrong!

In this example, since the masses are the same, each vehicle would come to a stop on impact because the masses are equal. This is equivalent to each vehicle striking a solid wall and decelerating from 60 mph to zero immediately. Hence, answer #2 is correct. If you remember your physics, momentum must be conserved, so both of these cars can’t have struck each other at the equivalent of 120 mph. The injuries sustained by any passengers will be those expected in a 60 mph crash.

If you change the scenario a little so that a car and a freight train are traveling toward each other at 60 mph each, the closing velocity is still 120 mph. However, due the the fact that the car’s mass is negligible compared to the train, it will strike the train, decelerate to 0, then accelerate to -60 mph in mere moments. The train will not slow down a bit. For occupants of the car, this would be equivalent to striking an immovable wall at 120 mph. The injuries will probably be immediately fatal for all.

Bottom line: Closing velocity has little relationship to the injuries sustained for most passenger vehicle crashes. Those injuries will be consistent with the speed of the vehicle the occupants were riding, and not the sum of the velocities of the vehicles.