New Guidelines for Anaphylaxis

The ALS guidelines for managing anaphylaxis have just been updated. It's a good time to both describe the changes, as well as explain why they were changed.

What Changed?
First, what was changed?

The ALS treatment for anaphylaxis has been changed from subcutaneous epinephrine to intramuscular, as well specifying injection in the thigh.

Let me show you the exact changes:

In addition, the guideline for allergic reaction was also changed:

Of course, the pediatric guidelines were changed as well, simplifying the dosing, and changing the route:

Okay, but why were the guidelines changed?
Fair question.

The use of SQ epi for anaphylaxis has been around for a while, and had previously been seen as the standard of care. EMT-Basics could use the Epi-Pen, and it may have been assumed that this was solely because they had to use a simpler, "fool-proof" system, while the ALS providers were trained to administer the standard treatment.

Ironically, though, the EMT-Basics have been the ones who have been providing the "state-of-the-art" therapy, while ALS providers have been held back!

Epi needs to go IM, in the thigh.
The best evidence shows that epinephrine is best given IM, in the thigh.

For example, in this study the researchers compared the levels of epinephrine in the blood after giving it either subcutaneously or intramuscularly, and either in the thigh or deltoid area.

This graph explains it all. The orange and yellow lines represent epinephrine given IM, in the thigh. The serum concentrations are clearly more elevated than the other methods. By contrast, SQ epi in the arm (green line) doesn't bump epinephrine levels much higher than the placebo injections!

What about Benadryl & Solu-Medrol?
There are no changes in the guidelines regarding these medications.

In fact, it's worth re-emphasizing that these medications are just adjunct treatments for anaphylaxis, and some experts do not consider them essential. I reviewed in a recent post ("Anaphylaxis Knowledge Among Paramedics") the misunderstandings that some paramedics have about this, and also about the contraindications for epinephrine in anaphylaxis.

(Spoiler: There are no contraindication to epinephrine in anaphylaxis.)

The Bottom Line
Paramedics, starting now, need to treat anaphylaxis with intramuscular epinephrine, in the thigh.

For the full Paramedic Treatment Guidelines, go to the website to download the updated  protocols (pdf).  EMT-Basics, on the other hand, can just keep using their "old" protocols.

Importance of the Prehospital ECG

I've talked about the evidence for liberal and frequent ECGs in the field. This, however, is not a literature review, but a "real-world" example.

A patient was brought into the ED recently, treated by Milford Fire. Fortunately for the patient, paramedic Eric Mohr was on duty, and did some nice ALS work.

EMS Course
 An elderly female had developed chest pain, abruptly, while asleep. It wasn't a mystery - she described "squeezing" pain that radiated to the jaw. The first ECG, from onscene, was not exactly a stumper either:

*** THE LP-12 IS VERY EAGER TO TELL YOU SOMETHING ***

Like I said, not subtle.

Transport was intiated, aspirin was given. They were just about to patch in and call for a cath-lab activation, but decoded to grab one more ECG as evidence. (Note the change in time - they switched to an LP-12 that hadn't been adjusted for daylight savings.)

Huh, no more STEMI. Or anything, really.

Furthermore, the patients pain was starting to resolve as well. Aside from brief period of sinus bradycardia that resolved with atropine, the patient's symptoms continued to improve.

In the ED
By the time they reached the ED, she was almost symptom-free. Our ECG was consistent with that of EMS - very, very normal.

More normal than mine. Seriously.

Tell me if you see anything there - I didn't.

Since the patient was now utterly symptom-free, with a normal ECG, I put her in a bed near the desk, and checked in every 10 or so minutes to see if she was feeling anything changes.

About an hour later, she reported the same feeling in her chest and jaw, and I grabbed another series of ECGs:

 

Hmmm. I wasn't sure if the one little change I was seeing was real, so we grabbed V4R (PDF download there). I don't have the actual ECG of that lead (by then there was practically a sheaf of tracings, and it got lost in the pile), but it stuck in my memory. Let me draw it for you:

V4R - According to the courtroom artist

As I described it to the cardiologist, "It's only about 0.25 mm, but that ST segment just wants to come up!"

This ridiculous interpretation of mine made sense to cardiology, and the cath lab was activated, despite the absence of classic STEMI criteria, and a patient whose symptoms had again resolved.

"Classic" STEMI criteria, from Rokos 2010.

Good thing too. She ended up having a 99% occlusion of the RCA.

From this episode, I think there are 2 lessons to take away.

EMS needs to grab ECGs early and often.
If Eric hadn't obtained that initial ECG, this would have been a far more difficult case. It was pretty clear from the onset that she had troubles with her inferior wall. This would have been very difficult to demonstrate solely on the subsequent ECGs, however.

Look at aVL
For this, I give all the credit to Stephan Smith. One of his frequent teaching points is that ST depressions or T-wave inversion in aVL is often the herald, the very first ECG indication of an impending inferior wall STEMI.

He has made this point recently, as well as on numerous prior occasions. Go read those, and look at the tracings, and see how the cases unfolded with EMS and in the ED. Pay special attention to how the emergency physician and cardiology approached the situation. These aren't straightforward cases, and goes beyond "STEMI 101."


The Bottom Line
Yes, it's true that you expect to see reciprocal changes in aVL and perhaps lead I, with an inferior wall MI.

But in a patient with ischemic-type symptoms, and no ECG changes expect for this pattern in aVL, keep your eyes open for ECG evolutions. Run a couple more strips. Grab some right-sided leads. Tell med control to meet you at the door to discuss the situation.

See you at 4 AM!

"Anaphylaxis Knowledge Among Paramedics"

As with any area in EMS, anaphylaxis generates a good amount of discussion. For example, people like to discuss the best way to give epinephrine intravenously. Other people can get really engaged in how glucagon might work in anaphylaxis (if it works). These conversations can get pretty involved in complicated biochemistry, or in personal experience, or even both.

Such discussions are interesting, but I get concerned that the central message about anaphylaxis treatment gets muddled and confused. Unfortunately, a recent study confirms my suspicions. 

The Bottom Line: How to treat anaphylaxis
Before reviewing the new study, it's worth emphasizing the current standard of care for the treatment of anaphylaxis:

• Epinephrine, 0.01 mg/kg (max 0.5 mg),
• delivered intramuscularly,
• in the lateral thigh. 

Not subcutaneous, not in the deltoid, and 0.3 mg is not the upper limit.

The Study
Okay, with  that established, I want to review a recent study that suggests that paramedics might often be confused about this issue. Why they're confused will be discussed below, but it comes down to, at least in part, education and medical control, I believe.

The study, "Anaphylaxis Knowledge among Paramedics", was performed in Missouri, and has a MD/paramedic as lead author! 

I don't usually get excited about studies that use a survey, and even less so when it's an online survey. A survey design can often just be a lazy way to get published.

" I'm in print! Things are going to start happening to me now." Me, in 2006.

 The authors really did their homework on the design though, and they ended up getting responses from about 5% of all nationally registry paramedics. Odds-wise, you work with someone who answered the survey.

They gave a few scenarios, and then asked both closed- and open-ended questions about anaphylaxis diagnosis and treatment. For example:

They also posed an atypical anaphylaxis scenario that was, at least for me, really hard to diagnose.

The results
Briefly, they found that most paramedics:

• Didn't pick epinephrine as the initial therapy (only 46% did so)
• Picked the wrong route for epi (just 39% chose IM)
• Picked the wrong location (a mere 12% described the thigh as the best site)
• Believe there are contraindications for epi in anaphylaxis (not according to the experts)

An uncharitable way to interpret the results is that many paramedics don't know how to treat anaphylaxis, and that they don't understand the lack of contraindication.

First, though, what is the best way to treat anaphylaxis?

Drug, Dose, Route
First off, repetition is the soul of learning:

• Epinephrine, 0.01 mg/kg (max 0.5 mg),
• delivered intramuscularly,
• in the lateral thigh. 

 Here's a cartoon that explains for the visual learners out there:

Recent World Health Organization (WHO) guidelines - download PDF!

The experts are all in agreement here, from EMS organizations (The use of epinephrine for out-of-hospital treatment of anaphylaxis: resource document for the National Association of EMS Physicians position statement.), to the allergists (Second symposium on the definition and management of anaphylaxis), to the World Health Organization (WHO), as shown above. 

What about diphenhydramine, steroids, glucagon, and all the other drugs? Well, they're fine to give, but they are not useful in acute management of anaphylaxis. In fact, one study, where they were trying to desensitize people with bee-sting allergies, only used epinephrine for the anaphylactic reactions they occasionally caused.

No Benadryl here.

Okay, so we're clear on how and why to give epi. Why did the medics think there were times when a patient in anaphylactic shock should not get epi?

Contraindications: A Review
About 36% of the medics listed contraindications to giving epinephrine for anaphylactic shock, which is concerning, since there are no absolute contraindication if the patient is having true anaphylactic shock. Here's a breakdown of the reasons they gave.

The most frequent concerns revolved around giving epinephrine to a patient with heart disease (or an older patient, and thus at risk of heart disease), and causing more problems. The recent WHO guidelines are reassuring, however, and I quote [my emphasis]:

"Although caution is necessary and dosing errors need to be avoided, epinephrine is not contraindicated in the treatment of anaphylaxis in patients with known or suspected cardiovascular disease, or in middle-aged or elderly patients without any history of coronary artery disease who are at in- creased risk of ACS only because of their age."

In fact, there is evidence to suggest that epinephrine protects the heart against ischemia, through dilation of coronary arteries. In fact, anaphylaxis often causes cardiac problems, such as ischemia, bradycardia, and sometimes MIs, and a cardiac arrest may result from incomplete treatment. 

Check out these examples:

Acute coronary syndrome triggered by honeybee sting: a case report.

ST-segment elevation myocardial infarction following a hymenoptera (bee) sting.

Acute anterior myocardial infarction after multiple bee stings.

Insect sting anaphylaxis; prospective evaluation of treatment with intravenous adrenaline and volume resuscitation.

I'm not sure about answer #2, ("allergy to epinephrine"), but let's just ignore that and move on...

Since a shock state may cause a reflex tachycardia, reason #3 seems more like an indication to give epi. Likewise, shock and hypotension (answer #6) pretty much define anaphylactic shock, so it's unclear how that would be a contraindication. If a patient with possible anaphylaxis were hypertensive, (#5), on the other hand, you could reasonably debate whether anaphylactic shock was a concern!

Why did paramedics do so poorly on the survey?
The authors discuss this at some length, but I'm inclined to blame, well, us. The medical directors, the educators, the state officials - the people who set the protocols and policies, as well as the curricula.

The change in the expert recommendations for epi administration happened years ago, but in many regions the protocols have not reflected this.

In fact, in some places, it is the EMT-Basics (who are limited to using the Epi-Pen) who are practicing at the current standard of care, since they have no option to give epi any other way.

Not a medic, but practicing the standard of care! (about.com)

Paramedics, however, with their expanded skill set, are able (and often required) to give it the ol' fashioned way. The not-quite-as-effective way. And until we change the protocols, medics are going to answer test questions based on what we require them to do.

The Bottom Line, part 2
While everyone likes to talk about the latest updates in ACLS, cool new devices for intubation, or new drugs or methods for cardiac arrest, EMS has not been as quick to pick up on the new, evidence-based treatment of anaphylactic shock.

And what is that, you ask? I'm so glad you asked!

• Epinephrine, 0.01 mg/kg (max 0.5 mg),
• delivered intramuscularly,
• in the lateral thigh.

 

Why paramedics need to read EKGs... Part III (Return of the EKG)

In this occasional series (see Part I and Part II) I have presented pairs of EKGs, typically with one that reads

*** *** ACUTE MI *** *** 

from one patient, and one that doesn't, from a second patient. The fun part is figuring out who went to the cath lab, who didn't, and why.

This time, however, while we still have 2 EKGs, there is only one patient.

"What a twist!"

The patient
A young fit man in his early twenties, was brought in by members of the local constabulary, complaining of chest pain. I was told that the symptoms were not typical of ACS, being pleuritic and mostly reproduced with palpation. He did not look particularly intoxicated, and denied any inciting trauma.

An EKG was obtained:

Hmm. I went to see the patient myself, and after a brief re-interview and exam, I requested "an intervention."

Thirty minutes later, a repeat EKG was obtained:

Some labs were obtained, they were fine, and he was released back into custody.

So what did I do?

Lytics, nitro, a bolus of magnesium? A door-to-ballon of 30 minutes? A precordial thump, indicated because... well, just because?

The intervention
I moved around the anterior chest leads, putting them in their proper location. His initial lead placement was disturbingly similar to that pictured here:

Courtesy CBS

My patient had had the V1 and V2 leads placed, not only a few interspaces too high, but also in different interspaces - the 2nd ICS for V1, and a subclavicular placement for V2.

Meanwhile, placement of V3 was optimized, as Brandon Otto has described, to monitor pancreatic function (the MPL3, perhaps?)

The Bottom Line
I don't want to drone on about lead placement, as I've already written at length about it. And sometimes it doesn't matter too much.

Other times, however, it certainly changes the picture!

EMS EKGs Don't Increase Onscene, Transport Time

 Scene times & bumpersticker philosophy
To the guy who came up with the phrase "Golden Hour;" thanks for nuthin'.

"There is a golden hour between life and death. If you are critically injured you have less than 60 minutes to survive. You might not die right then; it may be three days or two weeks later -- but something has happened in your body that is irreparable."    Attributed to Dr. Adam Cowley  Reference

Catchy phrases always seem to win out over nuanced discussion, and we are left in the position of having to justify any increment in pre-hospital time intervals. Given the very real dangers of traveling lights & sirens, we instead should have to justify speeding, running red lights, and other ways of "expediting" transport.

"I wonder if it was worth it to encourage all that risky driving..." Not attributed to Dr. Adam Cowley

Nonetheless, there are medical situations where rapid transport is indicated, and most people agree that a STEMI is one of them. And although prehospital ECG acquisition has been shown improve various outcomes, some people may still harbor the concern that taking the time to do the ECG is delaying definitive treatment.

The study

With that in mind, a study of prehospital time intervals was recently published by the folks out in San Diego. The authors of Pre-Hospital Electrocardiography by Emergency Medical Personnel: Effects on Scene and Transport Times for Chest Pain and ST-Segment Elevation Myocardial Infarction Patients. studied scene time and transport time for patients with chest pain. They used a before & after design to look at the differences in times after EMS implemented prehospital ECG acquistion.

They found a statistically significant increase in scene time and transport time after they started doing ECGs. The increases in times, however, were trivial,  accounting for an additional 14 and 12 seconds, respectively. It just goes to show that, if you have over 20,000 subjects in a study, you are going to find statistical differences that just don't matter.

Interestingly, if they only looked at the subset of patients whose Marquette interpretation was *** ACUTE MI ***, they found that those same time intervals decreased, such that the total scene-to-hospital time was almost 3 minutes faster than in the pre-ECG days. So, it appears that, if anything, EMS care is speeding up the care of the specific patient population in question. In particular, the transport time was almost a minute faster, leading the authors to comment: 

"It is possible that once identified, obvious and suspected STEMI patients were treated with greater urgency resulting in expedited transport to the closest STEMI center."

A note of caution

 While the paramedics likely treated the identified STEMI patients with "greater urgency," as the authors suggest, I am paradoxically concerned about such a large drop in transport time. How was this achieved? The study wasn't designed to answer that question, but another recent study suggests it was unlikely to be because a bunch of new cath labs were built in the area.

Instead, I am concerned that the dramatic reading of *** ACUTE MI *** prompted the drivers of the ambulances to "expedite" transport by driving warp factor 10. The problem is that, when the view through the windshield looks like this:

Pictured: about to bounce too close to a supernova.

... the next view could be something like this:

Aaaannnd, supernova. *

Let's be careful out there. Just getting the ECG is probably saving lives - don't risk them during transport, "golden hour" or not.

*Reference. Note that picture this is used for illustration, but the EMS crew apparently was neither responding nor transporting, and a car ran into them.