Category Archives: Prehospital

EAST 2019 #13: Geomapping Helicopter transports

Helicopter EMS (HEMS) transports are a valuable yet very expensive resource. Unfortunately, many state trauma systems or local EMS agencies do not provide specific guidance for best use. A group at the University of Alabama in Birmingham performed a geospatial analysis of helicopter transports in their area to determine the efficiency of HEMS operations.

This group created a sort of “heat map” that showed the number of transports overlaid on a geographical map of their catchment area. It included HEMS transports over a 6-year period directly from the scene. Drive and flight times were calculated, and the latter also included flight time to reach the scene.


Here’s the heat map showing the entire state of Alabama. The approximate location of Birmingham is indicated in yellow.

Here are the factoids:

  • Nearly 3000 patients were identified, and 1911 had scene locations recorded so analysis could be performed
  • 35% of patients had minor injuries with ISS 1-8 (!!)
  • Median flight time was 58 minutes, and median drive time was only 65 minutes
  • In 28% of cases, drive time would have been shorter than flight time when considering time for the helicopter to reach the scene
  • Conclusion: over one fourth of patients might have arrived at the hospital more quickly by ground ambulance

Here are some questions for the authors and presenter to consider in advance to help them prepare for audience questions:

  • Why include time for the helicopter to reach the scene but not a ground ambulance? Doesn’t this stack the deck in favor of ground transport?
  • Was there any correlation between scene proximity and high ISS? This might have been a reason for calling the helicopter.
  • Did you see any patterns in the low ISS group? This could provide insight into the EMS thought processes. These patients are potentially the low hanging fruit to direct educational activities to reduce HEMS use.

This is thought-provoking work and I look forward to hearing all the details!

Reference: Use of helicopters for retrieval of trauma patients: a geospatial analysis. EAST 2019, Quick Shot Paper #26.

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Best of AAST #4: Better Triage For Scene Helicopter Transport

There has been tremendous debate around the value and use of prehospital helicopter emergency medical services (HEMS). It’s fast, but also expensive, and there is always a small amount of added risk to patients during transport. Over the years, there has been a significant increase in the number of helicopter services, and in some cases it seems like several services are dashing to accident scenes in the hope that they can pick up the patient.

Overuse of HEMS has also been recognized, with some patients transported who could have just as easily and safely been moved by ground ambulance. This is a particularly vexing problem with pediatric patients.

The holy grail of trauma HEMS has been to find some easy to identify scene variables that reliably predict which patients should be transported by air. A group in North Carolina tapped the state trauma registry to attempt to develop such a system. They analyzed data in the registry over a three year period, mathematically analyzing for easily identified predictors of ED death or need for operating room, interventional radiology, or ICU admission.

Here are the factoids:

  • The percentage of flights from the scene increased from 7% to 9% compared to data from fifteen years prior to this study
  • Vital signs (SBP, pulse, GCS motor) had the best correlation with mortality, and these were used to develop a regression model for triage
  • Patients with normal SBP, pulse, and GCS motor of 6 were found to safely transported by ground EMS, with similarly low mortality for ground or air
  • During the study period, triaging patients that met these criteria would have saved the state system about $19 million

Bottom line: Every state should take a look at their guidelines for helicopter vs ground transport for scene runs. This is an expensive tool, and should be treated with respect. Just because a helicopter is available does not mean it should be used. The commander on the scene must make the proper decision based on variables like these, but also apply their knowledge of traffic patterns, time and distance from the most appropriate receiving trauma center.

Reference: Trauma system resource preservation: a simple scene triage tool can reduce helicopter emergency medical services (HEMS) over-utilization in a state trauma system. Session IV Paper 13, AAST 2018.

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Uber / Lyft For Medical Transport???

In this day and age of ride sharing apps like Uber and Lyft, it is possible to get a cheap ride virtually anywhere there is car service and a smart phone. And of course, some people have used these services for transportation to the hospital in lieu of an ambulance ride. What might the impact be of ride services on patient transport, for both patient and EMS?

A paper in preparation suggests that ambulance service calls decreased by 7% after the introduction of UberX rides. Now, there are a lot of questions here, because the full paper has not yet been peer reviewed, and the results write-up is pretty sketchy. But it does beg the question.

Ambulance rides are expensive. Depending on region, they may range from $500-$5000. And although insurance may reduce the out of pocket cost, it can still be expensive. So what are the pros vs the cons of using Uber or Lyft for medical transport?

Pros:

  • Ride shares are inexpensive compared to an ambulance ride
  • They may arrive more quickly because they tend to circulate around an area, as opposed to using a fixed base
  • Riders may select their preferred hospital without being overridden by EMS (although it may be an incorrect choice)
  • May reduce EMS usage for low acuity patients

Cons:

  • No professional medical care available during the ride
  • May end up being slower due to lack of lights and siren
  • Damage fees of $250+ for messing up the car

Bottom line: Uber and Lyft are just another version of the “arrival by private vehicle” paradigm. Use of these services relies on the customer/patient having very good judgment and insight into their medical conditions and care needs. And from personal experience, this is not always the case. I would not encourage the general public to use these services for medical transport, and neither do the companies themselves!

Reference: Did UberX Reduce Ambulance Volume? Unpublished paper, October 24, 2017.

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Can Prehospital Providers Accurately Estimate Blood Loss? Part 2

I’ve previously written about the difficulties estimating how much blood is on the ground at the trauma scene. In general, EMS providers underestimated blood loss 87% of the time. The experience level of the medic was of no help, and the accuracy actually got worse with larger amounts of blood lost!

A group in Hong Kong developed a color coded chart (nomogram) to assist with estimation of blood loss at the scene. It translated the area of blood on a non-absorbent surface to the volume lost. A convenience study was designed to judge the accuracy that  could be achieved using the nomogram. Sixty one providers were selected, and estimated the size of four pools of blood, both before and after a 2 minute training session on the nomogram.

Here’s what it looks like:

Note the areas across the bottom. In addition to colored square areas, the orange block is a quick estimate of the size of a piece of paper (A4 size since they’re in Hong Kong!)

Here are the factoids:

  • The 61 subjects had an average of 3 years of experience
  • Four scenarios were presented to each: 180ml, 470ml, 940ml, and 1550ml. These did not correspond exactly to any of the color blocks.
  • Before nomogram use, underestimation of blood loss increased as the pool of blood was larger, similar to the previous study
  • There was a significant increase in accuracy for all 4 scenarios using the nomogram, and underestimation was significantly better for all but the 940ml group
  • Median percentage of error was 43% before nomogram training, vs only 23% after. This was highly significant.

Bottom line: This is a really cool idea, and can make estimation of field blood loss more accurate. All the medic needs to do is know the length of their shoe and the width of their hand in cm. They can then estimate the length and width of the pool of blood and refer to the chart . Extrapolation between colors is very simple, just look at the line. The only drawback I can see occurs when the blood is on an irregular or more absorbent surface (grass, inside of a car). 

Related posts:

Reference:  Improvement of blood loss volume estimation by paramedics using a pictorial nomogram: a developmental study. Injury article in press Oct 2017.

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