Category Archives: Prehospital

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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Can Prehospital Providers Accurately Estimate Blood Loss?

EMS providers are the trauma professional’s eyes and ears when providing transportation from the scene of an accident. We rely on their assessment of the mechanism of injury and the amount of blood lost. We tend to believe in the accuracy of those assessments.

A study was carried out that tested EMS personnel on their ability to accurately estimate specific amounts of blood that were left at a simulated accident scene. The blood volumes tested were 500cc, 1000cc, 1500cc and 2100cc. A total of 92 professionals participated, and there was an even split into basic EMTs (34%), intermediate/critical care EMTs (33%) and paramedics (31%). Experience levels were as follows: 0-5 years 43%, 6-10 years 30%, >10 years 31%.

The results were as follows:

  • 87% underestimated the quantity of blood
  • 9% overestimated
  • 4% guessed the exact amount
  • Experience or credentialing level did not matter

Only 8% of the subjects were within 20% of the actual volume, and an additional 19% were within 50%. In general, most medics underestimated the amount of blood lost, and their guesses were worse with higher volumes. The median guess for the 2100cc loss group was only 700cc!

EMS Blood Loss Estimates

Bottom line: Visual estimates of blood loss are extremely inaccurate, and are most likely  underestimates. Physicians in the ED should rely on exam and physiology to help determine the amount of blood loss. For safe measure, multiply the reported blood loss of the EMT or paramedic by 2 or 3 to get a realistic number.

Reference: Patton et al. Accuracy of Estimation of External Blood Loss by EMS Personnel. J Trauma 50(5), 914, 2001.

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Uber / Lyft For Medical Transport???

Yesterday I discussed nonstandard first responders (police). Today I’ll share some info on nonstandard ambulances.

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.

(This paper remains unpublished! Hmm… but the link will take you to a copy of the manuscript)

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Trauma Patient Transport By Police, Not EMS

When I was at Penn 30+ years ago, I was fascinated to see that police officers were allowed to transport penetrating trauma patients to the hospital. They had no medical training and no specific equipment. They basically tossed the patient into the back seat, drove as fast as possible to a trauma center, and dropped them off. Then they (hopefully) hosed down the inside of the squad car.

Granted, it was fast. But did it benefit the patient? The trauma group at Penn decided to look at this to see if there was some benefit (survival) to this practice. They retrospectively looked at 5 years of data in the mid-2000’s, thus comparing the results of police transport with reasonably state of the art EMS transport.

They found over 2100 penetrating injury transports during this time frame (!), and roughly a quarter of those (27%) were transported by police. About 71% were gunshots vs 29% stabs.

Here are the factoids:

  • The police transported more badly injured patients (ISS=14) than EMS (ISS=10)
  • About 21% of police transports died, compared to 15% for EMS
  • But when mortality was corrected for the higher ISS transported by police, it was equivalent for the two modes of transport

Although they did not show a survival benefit to this practice, there was certainly no harm done. And in busy urban environments, such a policy could offload some of the workload from busy EMS services.

Bottom line: Certainly this is not a perfect paper. But it does add more fuel to the “stay and play” vs “scoop and run” debate. It seems to lend credence to the concept that, in the field, less is better in penetrating trauma. What really saves these patients is definitive control of bleeding, which neither police nor paramedics can provide. Therefore, whoever gets the patient to the trauma center in the least time wins. And so does the patient.

Related posts:

Reference: Injury-adjusted mortality of patients transported by police following penetrating trauma. Acad Emerg Med 18(1):32-37, 2011.

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Trauma Activation vs Stroke Code

Let’s look at an uncommon scenario that crops up from time to time. Most seasoned trauma professionals have seen this one a time or two:

An elderly male is driving on a sunny afternoon, and crashes his car into a highway divider at  25 miles per hour. EMS responds and notes that he has a few facial lacerations, is awake but confused. They note some possible facial asymmetry  and perhaps a bit of upper extremity weakness. No medical history is available. Witnesses state that he was driving erratically before he crashed. Medics call the receiving trauma center in advance to advise them that they have a stroke code.

Is this a reasonable request? Stroke centers pride themselves on the speed of their stroke teams in assessing, scanning, and when appropriate, administering thrombolytics to resolve the problem. But if there are suspicions of stroke in a trauma patient, which diagnosis wins? Trauma team or stroke team?

Lets analyze this a bit further, starting with diagnosis. Remember the first law of trauma:

Any anomaly in your trauma patient is due to trauma, no matter how unlikely it may seem.

Could the symptoms that the paramedics are observing be due to the car crash? Absolutely! The patient could have a subdural or epidural hematoma that is compressing a cranial nerve. There might be a central cord injury causing the arm weakness. His TBI might be the source of his confusion. The facial asymmetry could be due to a pre-existing Bell’s palsy, or he could have had a stroke years ago from which he has only partially recovered.

If the stroke team is called for the patient, they will focus on the neuro exam and the brain. They will not think about trauma. They will follow the patient to CT scan looking for the thing that they do best with. If they don’t see it, the patient will return to the ED for (hopefully) a full trauma workup. If there are occult injuries in the abdomen, then the patient may have been bleeding for an hour by then. This elderly patient will then be way behind the eight ball.

And let me pose the worst case scenario. The patient is taken to CT by the stroke team, and lo and behold he has a thrombotic stroke!  This patient had a stroke, which caused him to lose control of his car and explains most of his findings. Again, the stroke team will do what they are trained to do and give a thrombolytic. They are still not thinking about trauma. Within minutes the patient becomes hypotensive and his abdomen appears a bit more distended. He is rushed back to the ED (remember, no CT in hypotensive patients even if you are in the scanner) and a FAST exam is very positive for free fluid throughout the abdomen. Imagine the look you will get from the surgeon as they run to the OR to perform a splenectomy on this fully anticoagulated patient!

Bottom line: If you have a patient who is trauma vs stroke, trauma always wins! Remember the first law and try to find traumatic reasons for all signs and symptoms. Perform your standard trauma workup and incorporate the appropriate head scans into your evaluation. Then and only then should the stroke team be called.

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