5 must-read EMS research studies from 2015

A look at some of the research from the last year, why it’s important and what it means for paramedic chiefs and EMS field providers


Every year, dozens of research studies relevant to the EMS profession are published. Some lead to new treatments, while others prove accepted therapies may not be effective. Others simply open our eyes to new ideas and challenges, even if the results are ambiguous.

Here are five research studies from 2015 that every EMS leader and paramedic chief needs to read. These articles might change the way you think about what we do and how we do it.

1. Is continuous chest compression CPR effective?
Nichol, Graham, et al. "Trial of continuous or interrupted chest compressions during CPR." New England Journal of Medicine 373.23 (2015): 2203-2214.

This study made my list for what it reported and its scale. Performing research in EMS is not easy. With an uncontrolled environment, and so many factors to take into account, randomized control trials (where a treatment is compared to a control or placebo) are often difficult to conduct and prohibitively expensive.

The research team trained EMS providers across 147 agencies in eight different sites on two different protocols. One protocol was standard CPR, 30 compressions to 2 ventilations, with just a five second or less pause for breaths. The other protocol involved continuous compressions, with asynchronous positive-pressure breaths every ten seconds. Each agency switched protocols periodically throughout the 4 years of the study.

At the conclusion of the study, more than 20,000 patients were included in the analysis: 12,653 in the continuous compression group, and 11,058 in the 30 to 2 group. The researchers looked at different outcomes, including both survival-to-discharge and neurological status.

What they found was that the two groups had very similar survival rates — 9 percent in the continuous compression group, and 9.7 percent in the control group — a difference that was not statistically significant.

This finding may come as a surprise after previous studies indicated that continuous compressions resulted in higher survival rates. However, the authors point out several reasons for these differences. For one, many of those earlier studies compared survival rates before and after initiation of new protocols. In those cases, the improved survival rates may have been due to other treatment changes that were happening at the same time, or simply due to a renewed focus on chest compressions. It’s often the case in EMS that we change several aspects of a protocol, and then attribute improvements in outcome to one of those changes without knowing for sure if it was the one that made the difference.

This study is a reminder that we should sometimes be cautious before jumping on the bandwagon of new treatments or trends in EMS. One local agency near me recently spent a lot of effort training hundreds of EMS providers on continuous compressions with ventilations, while perhaps just emphasizing the importance of minimizing pauses with the previous 30 compression to 2 ventilation protocol would have been just as effective.

At the same time, we can’t write off continuous compressions. This study only tested continuous compressions with positive pressure ventilation. It did not look at other potential solutions, such as compressions with passive ventilation, such as a non-rebreather mask, or with no supplemental oxygen.

2. Do the patient’s race and sex impact care?
Govindarajan, Prasanthi, et al. "Race and Sex Disparities in Prehospital Recognition of Acute Stroke." Academic Emergency Medicine 22.3 (2015): 264-272.

Researchers in California tried to determine if a patient’s race or sex was associated with an EMS provider’s ability to recognize a stroke.

This study had several limitations — it was retrospective, meaning the authors looked at EMS and hospital records after the fact. To determine whether or not EMS correctly recognized the stroke, for example, researchers used the primary impression field from the patient care report. The amount of training paramedics received on completing this field in the PCR was not described.

For example, a patient with altered mental status, a headache and one-sided weakness could have a primary impression of any of those three complaints. Listing altered mental status for a patient with acute stroke signs would not have been considered incorrect nor would it necessarily mean that the stroke wasn’t recognized or the hospital wasn’t alerted in advance. This is why documenting stroke scales and hospital notifications are so critical to quality improvement and research.

That being said, the results of this study should not be ignored. The authors found that EMS providers were less likely to recognize strokes in females than in males, and in Asians and Hispanics compared to whites.

To be clear the results of this study do not mean that EMS providers are sexist or racist. It could mean that there is bias among providers, but it could also mean that stroke symptoms present differently, or that communication barriers exist. What’s important is that we further study the disparities and acknowledge that gender and cultural differences impact the care we provide every day.

3. Can stroke scales be more sophisticated?

Katz, Brian S., et al. "Design and Validation of a Prehospital Scale to Predict Stroke Severity Cincinnati Prehospital Stroke Severity Scale." Stroke 46.6 (2015): 1508-1512.

I picked a second stroke study because it points to the promise of prehospital research and the potential to improve care. I also think stroke is a condition that is often overlooked for the more dramatic patients, such as trauma, cardiac arrest and heart attack victims.

New stroke treatments have led experts to question whether there might be ways for EMS providers to distinguish large-vessel occlusions (LVO), which are strokes that impact the major vessels in the brain, from other ischemic strokes. LVO patients seem to have better outcomes if they receive timely endovascular therapy (mechanical retrieval of the clot), not just medical treatment (such as administration of tpa to dissolve the clot). If prehospital providers could identify patients with LVO, they might be able to triage them to the most appropriate care, potentially a facility that provided mechanical interventions for stroke.

It makes sense that researchers from Cincinnati tackled this topic, as the Cincinnati Prehospital Stroke Scale is well known and the most commonly used stroke scale in EMS. They are not the first ones to address this issue. In 2014 a group of researchers in Spain published the RACE (Rapid Arterial Occlusion Evaluation) scale.

The validation of the Cincinnati Prehospital Stroke Severity Scale (CPSSS) was performed retrospectively, meaning the researchers looked at a previously existing data set to see if their scale could have identified the patients who were given a score of 15 or more on the National Institutes of Health Stroke Scale (NIHSS), which has a high correlation with severe strokes and LVO.

The CPSSS consists of just a few items:

  • Conjugate gaze deviation (2 points).
  • Incorrectly answers questions about age or month and does not follow commands (1 point).
  • Cannot hold arm (either one or both) up for 10 seconds (1 point).

If the patient scored 2 or greater, there was a high correlation with scoring 15 or more on the much more complex and detailed NIH scale. For identifying LVO, the CPSSS was 83 percent sensitive and 40 percent specific, meaning it correctly identified 83 percent of LVOs but had a much lower rate of correctly identifying people without LVO. When triaging people for such conditions, a high sensitivity and lower specificity is often considered acceptable, as it is considered better to over-triage in order to avoid ever missing an actual case.

While there is still much work to be done to evaluate and validate stroke scales’ ability to identify severe strokes and LVO in the prehospital setting, this paper and others like it are promising. With conditions such as stroke, the most important thing EMS can do is recognize the symptoms and get patients to the most appropriate hospital. As treatments continue to be refined, the ability to identify more severe strokes may present an opportunity for prehospital providers to play a major role in improving outcomes for stroke victims.

4. Can EMS providers effectively enroll subjects into a randomized control placebo trial?
Saver, Jeffrey L., et al. "Prehospital use of magnesium sulfate as neuroprotection in acute stroke." New England Journal of Medicine 372.6 (2015): 528-536.

This is another study related to stroke, but it’s not in here because of that. In the Field Administration of Stroke Therapy — Magnesium Trial (FAST-MAG), a large, multi-agency randomized control trial was conducted to test the efficacy of prehospital administration of magnesium sulfate to stroke patients as a neuroprotective agent.

The authors concluded that the "trial did not show a treatment benefit of magnesium sulfate administered in the prehospital setting among patients in whom hyperacute stroke was suspected."

What’s fascinating about FAST-MAG is not the results, but the methods — a section of research articles often overlooked. In ambulances across Los Angeles and Orange County, the researchers managed to conduct a large, blinded placebo trial. That means that during the study, paramedics administered a drip to stroke patients without knowing each time if it was magnesium or a placebo (a drip without the medication, such as normal saline). This helps ensure that the administration is random, and patients aren’t chosen to receive the medication because they are in better or worse condition.

Blinded, randomized control trials are the gold standard in medical research. They are difficult enough in hospitals, let alone the prehospital setting. More studies like this need to be performed, not simply to test new treatment possibilities, but also to affirm some current practices that have never been validated with clinical research.

5. Does ALS make a difference in patient outcomes?
Sanghavi, Prachi, et al. "Outcomes after out-of-hospital cardiac arrest treated by basic vs advanced life support." JAMA internal medicine 175.2 (2015): 196-204.

This article received a lot of attention when it was published, so you may already be familiar with it. The study argued that cardiac arrest patients who received BLS care fared better than those who received ALS care. In some EMS circles, the research was dismissed outright, with people arguing that it was meaningless. I disagree.

Yes, the study is limited because it used Medicare data, so the vast majority of patients were elderly. The results might look different if middle-aged cardiac arrest victims were included. And while it is true that researchers can’t control for everything, statistical analyses in medicine often control for factors such as patient severity or initial rhythm. In my opinion, the biggest flaw is how they determined BLS versus ALS care. By using billing codes instead of actual treatments provided, it is unclear exactly what interventions the patients received.

But before we dismiss the research completely, we should ask ourselves: If the same study had shown that ALS made a difference, would we be pointing out the limitations in the research? As health care providers, we need to be willing to admit when something we do is not effective and adapt when treatment paradigms change. The constantly changing nature of EMS — the fact that what I learned as gospel in EMT class might not be true anymore — is precisely what makes it so much fun.

Perhaps instead of criticizing ALS, what this study is really doing is showing how effective EMS has been at getting the right treatments to the right patients and giving them a chance to survive. We know that the most important treatments for cardiac arrest are compressions and defibrillation, so we’ve made those BLS (and layperson) skills. Is it any surprise that the providers who focus on those evidence-based interventions might have better outcomes than those of us who are also performing more advanced procedures that may or may not provide any benefit?

Regardless of whether the study is perfect (certainly not) or a complete waste of time (also not the case), what is clear is that more and more research like this is on the horizon. As health care costs continue to account for big chunks of government and corporate spending, prehospital providers (like everyone else) need to be prepared to defend their actions with evidence. If we charge a patient twice as much for an ALS ambulance, we should only assume that at some point, the people who are paying will want to see what they’re getting in return. It’s time we start embracing these studies and realizing that each one contributes in a small way to building a base of knowledge and ensuring that we are always striving to improve the quality and efficiency of patient care.

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