Airway & Respiratory, Patient Care

Critical Updates in Assessment & Management of Anaphylaxis

Issue 10 and Volume 38.

“Medic 1, respond. 38 year old female, unresponsive. No further information known.”

After your arrival at a private residence for an unresponsive patient, you and your colleagues are rushed into the backyard. The scene appears safe and no chemicals are visible on scene survey

Your patient is an adult female, whose friend and only available bystander reports her to be in usually good health.

Primary survey reveals the airway is intact, breathing is normal in rate and effort, and pulse is absent at the radial site and weakly present at the carotid site at a normal rate.

The patient is unresponsive to verbal and tactile stimuli. You aren’t certain what’s causing this patient’s distress, though you are certain she’s seriously ill, so quick attempts to stabilize her are essential.

You direct a fellow paramedic to establish vascular access and check her blood glucose while an EMT obtains a set of vital signs and places the patient on the ECG monitor. All of these interventions are done simultaneous with your rapid secondary assessment and additional history attempts. No visible trauma can be found. Pupils are midpoint and reactive. Lung sounds are clear and equal. Her abdomen is soft and nondistended. Neuro status is hard to accurately assess, though it doesn’t appear there are any focal signs of weakness or other deficit. The skin is warm, pink and dry. There’s no rash.

The patient wears no medical condition alert bracelets or necklaces. Her friend is trying to be helpful by answering your questions, but is obviously distracted by the recent events and is getting more worried, especially after taking in your looks of obvious concern for this patient’s survival—but survival from what?

No, the patient’s friend doesn’t think she takes medication on a regular basis and doesn’t think she would overdose on anything. No, her friend can’t remember something like this ever happening before.

Yes, her friend confirms the patient is normally quite active and in very good health as far as she’s ever known.

IV access proves difficult—not surprising in the face of cardiovascular collapse—and blood glucose by fingerstick is 110 mg/dL.

Blood pressure is unreadable, both by automated cuff and by manual attempt, and by a good EMT at that. “Please, what’s going on?” asks the patient’s friend. All you can think of is asking yourself the same question. Before you can, though, the ECG monitor alarms, “No pulse, start CPR.”

“Do you think the wasp sting caused any of this?” the patient’s friend suddenly asks you. What wasp sting? Now, you quickly reassess your patient. Urticaria? No. In fact, you can’t even find the sting site. Wheezing or any kind of respiratory distress? No. Vomiting or diarrhea? No.

But if this was anaphylaxis, those signs would be there, right? Not always, and the treatment window is about to close unless you give the only drug that will make the critical difference, and give it now—in the right dose and via the right route. Would you save this patient today with your current knowledge and standards of care? What if a bystander didn’t prompt you with history?

All front-line EMS apparatus in the EMS System for Metropolitan Oklahoma City and Tulsa, Okla., have epinephrine autoinjectors for use by BLS providers.

All front-line EMS apparatus in the EMS System for Metropolitan Oklahoma City and Tulsa, Okla., have epinephrine autoinjectors for use by BLS providers. 

Practice vs. Theory

This case isn’t theory. It’s based on a real-world battle for survival, one won by a patient because of the care provided by excellent EMS professionals who understood anaphylaxis presents beyond the traditional textbooks and must be treated aggressively on scene and enroute to be lifesaving.

Questions you likely have already: Why anaphylaxis? Didn’t JEMS run a great basic pathophysiology piece on anaphylaxis last year? (See the August 2012 issue for Rick Rod’s instructive review, “Sudden Onset: Be prepared to treat anaphylactic incidents before it’s too late.”)

Besides, anaphylaxis has been around for a long time. Is there really anything new about something so old? And what is this “praxis” thing, anyway? Great questions, Life-Savers. The answers you deserve are woven throughout the rest of this article, so your interest only grows from here!

Let’s take your last question first. Praxis can be defined in numerous ways. The first definition in Merriam-Webster’s Collegiate Dictionary is “practice as distinguished from theory.” That’s a great fit for our EMS practice of medicine, isn’t it? We don’t just mull over how illness affects someone, we directly intervene in that illness process using our knowledge; and in a life-threatening situation (or nearly life-taking as in our patient’s case), we can make the difference.

The second known definition is “an accepted practice or custom.” That works well when the customary treatment is correct. This article will challenge what’s been the customary use of epinephrine in anaphylactic adults and challenge you to make the necessary changes for your next anaphylaxis encounter. (These changes, of course, need to be approved by your local medical oversight physician to become the standing order standards of care for your community.)

Finally, the third—and best—definition of praxis is “acts that shape and change the world.” When you make the difference in life and death, you shape and change that patient’s world and everyone’s world that patient will then have the opportunity to impact. This is big stuff, and it doesn’t even involve trauma by gun, knife or twisted metal.

New Clinical Standards

Anaphylaxis is one of the few true medical emergencies in which time is so critical that EMS professionals don’t just get to be difference makers, we have to be the difference makers. Within 5–10 minutes of allergen exposure (e.g., foods such as peanuts, medications like antibiotics and insect stings), or of a sudden, unexpected mastocytosis attack (a rare condition releasing massive amounts of histamine causing cardiovascular collapse, skin changes, respiratory distress, and/or gastrointestinal distress), the anaphylaxis cascade of clinical decompensation can prove fatal.

If you’ve been in EMS for any length of time, you likely initially learned that epinephrine can save a life—and it can take one, too! You probably remember being taught that giving epinephrine to someone with a pulse was dangerous business, especially if they’re older and have heart disease.

If you did give epinephrine to an anaphylactic adult, it might require a physician order to administer what would likely be a dose of 0.3 mg of 1:1000 epinephrine via a subcutaneous injection, often in the arm. That’s the way the standard of care was for more than 25 years.

The World Allergy Organization (WAO) and the American Academy of Asthma, Allergy and Immunology (AAAAI) have endorsed important new clinical standards for anaphylaxis that must be known to practice optimal EMS medicine. Epinephrine hasn’t changed in structure, but the dosing and administration route have both been distinctly updated in these recommendations. Adult anaphylaxis patients should receive epinephrine 1:1000 at 0.01mg/kg up to 0.5 mg a dose. That functionally translates to essentially every adult you treat needing 0.5 mg. Is that your current practice? The majority of EMS systems have yet to translate this latest science from the WAO and AAAAI into their treatment protocols. Talk to your physician medical director if yours has not.

While you’re discussing your anaphylaxis standards of care with your supportive physicians, also make sure to discuss the route and site of administration of this increased dose of epinephrine. Studies now confirm that intramuscular (IM) administration will get epinephrine into circulation faster than the traditionally taught subcutaneous approach. The muscle used for delivery matters as well. It’s most effective to use the anterior thigh musculature as opposed to reaching for the deltoid, which also challenges traditional IM-site teaching. In cases of morbid obesity, the proximal thigh’s adipose tissue will prove a barrier to reaching the muscle with the needles typically used in EMS and EDs, so factor that into a decision to use the distal anterior thigh muscle in some patients.

Whichever aspect of the anterior thigh musculature is used, massage the site used for approximately 30 seconds post injection to further speed epinephrine uptake. Remember, time in anaphylaxis really is measured in mere minutes.

Pediatric dosing of 1:1000 epinephrine remains the same as the traditionally taught 0.01 mg/kg up to 0.3 mg. The administration, though, has also changed to mirror all the adult updates just discussed in IM selection.

Regardless of patient age, don’t be afraid to repeat dose administration epinephrine every 5–15 minutes if the patient is not improving.

Figure 1: Oklahoma EMS Protocol 8D: Acute Allergic Reactions (BLS)

Figure 1: Oklahoma EMS Protocol 8D: Acute Allergic Reactions (BLS)

Changing Protocols

Now that you’re confident in the dosing and site of administration for epinephrine, it’s time to focus on the biggest point of this article, highlighted in our patient’s presentation. If you remember only one thing from this article, make it this: Anaphylaxis can present as cardiovascular collapse alone. If you don’t think of an illness you can’t treat it, so remember there’s a critical minority of patients who only respond to an allergen by dumping pressure, with or without tachycardia.

Certainly, the majority of anaphylaxis victims will have at least two of the four classic signs:

1. Urticaria (hives) or angioedema (swollen mucous membranes);
2. Respiratory difficulty (usually manifesting with wheezing);
3. Gastrointestinal symptoms of nausea, vomiting and/or diarrhea; and
4. Hypotension.

Hypotension is defined in the WAO and AAAAI guidelines in absolute terms as less than 90 mmHg systolic blood pressure in adults and less than typical age-related blood pressures in pediatrics, as calculated by the formula of 70 + 2x age in years for systolic blood pressure. (Hypotension is also defined in the WAO and AAAAI guidelines in relative terms as a greater than 30% decrease from the individual patient’s usual systolic blood pressure. Although the relative term can be helpful, and realistically used in some EMS patient encounters, most of our patients are unfamiliar with their usual blood pressures and we more commonly rely upon absolute terms in recognizing hypotension.)

Be the clinical detective and don’t forget anaphylaxis on your differential diagnosis list when confronted with initially-unexplained anaphylaxis. Despite our encouragements for epinephrine use, the authors and EMS medical oversight physicians will still want you to consider the patient’s age and comorbid factors rather than a cavalier approach to epinephrine. A recommended allergic reaction protocol, inclusive of all these anaphylaxis treatment recommendations, can be found at and is replicated in part here. (See Figure 1, above.)

This protocol allows for use of autoinjector epinephrine by EMTs in Oklahoma City and Tulsa, Okla., for anaphylaxis. Does your service allow the same in BLS scope of practice? Why or why not? Particularly for rural EMS services without paramedics or that rendezvous with paramedics after prolonged treatment courses, autoinjector epinephrine can be the lifesaving difference.

The authors encourage you to seriously contemplate and take action in placing these devices on your BLS apparatus if not already the standard. All front-line EMS apparatus in the EMS System for Metropolitan Oklahoma City and Tulsa have either epinephrine autoinjectors (BLS) or epinephrine 1:1000 ampules (ALS) for this very reason.

Anaphylaxis can sometimes present as cardiovascular collapse alone.

Anaphylaxis can sometimes present as cardiovascular collapse alone.


You likely chose an EMS career to be in a position to make a critical difference and save lives. The correct and aggressive attack on anaphylaxis will allow you to realize that goal, making the most important difference in a life far too healthy to end otherwise.

We wish you the very best in helping these very sick patients and welcome your questions and interest.


1. Jacobsen RC, Millin MG. The use of epinephrine for out-of-hospital treatment of anaphylaxis: resource document for the National Association of EMS Physicians position statement. Prehosp Emerg Care. 2011;15(4):570–576.
2. Jacobsen RC, Toy S, Bonham AJ, et al. Anaphylaxis knowledge among paramedics: Results of a national survey. Prehosp Emerg Care. 2012;16(4):527–534.
3. National Association of EMS Physicians. The use of epinephrine for out-of-hospital treatment of anaphylaxis. Prehosp Emerg Care. 2011;15(4):544.
4. Simons FE, Ardusso LR, Bilò MB, et al. World Allergy Organization anaphylaxis guidelines: summary. J Allergy Clin Immunol. 2011;127(3):587-93.e1–22.
5. Simons FE, Ardusso LR, Bilo MB, et al. 2012 Update: World Allergy Organization guidelines for the assessment and management of anaphylaxis. Curr Opin Allergy Clin Immunol. 2012;12(4):389–399.
6. Vanden Hoek TL, Morrison LJ, Shuster M, et al. Part 12: Cardiac arrest in special situations: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2010;122(suppl 3):S829–S861.
7. Walker DM. Update on epinephrine (adrenaline) for pediatric emergencies. Curr Opin Pediatr. 2009;21(3):313–319.

Epinephrine Autoinjectors

The ABCs of Epinephrine Autoinjectors

The epinephrine autoinjector puts the single most-effective drug for anaphylaxis in the hands of all EMS professionals certified as EMTs or higher. Although paramedics often administer diphenhydramine (Benadryl) and methylprednisolone (Solu-Medrol) in cases of anaphylaxis, the fact is that both medications don’t exert their effects until far too late to reverse truly life-threatening anaphylaxis. The bottom line is this: If you are treating anaphylaxis, the patient needs epinephrine and they need it now! There are presently three epinephrine autoinjectors that you may encounter: EpiPen, Auvi-Q (Allerject in Canada) and TwinJect.

EpiPen is probably the most well-known because it’s been around the longest. EpiPen contains 0.3 mg of epinephrine 1:1000 and EpiPen Jr. for pediatric use contains 0.15 mg of epinephrine 1:1000. If you trained on EpiPen a few years ago, you may remember being instructed that it you had to remove protective caps from both ends of the autoinjector. This is an important update: Current EpiPen manufacturing requires that you only remove the blue safety-release cap when ready to administer. During administration, never put your thumb, fingers or your hand over the orange tip where the needle comes out.

In the rush to self-treat in an admittedly frightening condition, patients may accidentally mix up the sides in any autoinjector and find themselves getting an injection of epinephrine in their hand or finger. We used to think this would cause serious perfusion problems in a finger, though more recent research has shown this vasoconstriction is temporary, and while a bit painful at times, will not lead to the loss of a finger.

Auvi-Q/Allerject is newest to the epinephrine auto-injector market. It is shaped substantially different and smaller than the EpiPen as part of the manufacturer’s marketing strategy. Unique to this autoinjector is a self-contained speaker that emits step-by-step injection instructions when the protective cap is removed. In the U.S., patients who are prescribed Auvi-Q will receive a two-pack of active autoinjectors and a trainer injector with which they can repeatedly practice injections. There is no needle or medication in this trainer. Sanofi-Aventis, the manufacturer of Auvi-Q, also has a smartphone app that turns your phone into a virtual trainer. In your phone’s app store, search for “Auvi-Q” to find this application. Auvi-Q/Allerject comes in adult dosing of 0.3 mg of epinephrine 1:1000 in a red injector and in pediatric dosing of 0.15 mg of epinephrine 1:1000 in a blue injector.

Twinject may still be encountered in patients with previously-filled prescriptions, but it is presently not being manufactured. This autoinjector is really a two-in-one injector, with a second dose of epinephrine 1:1000 0.3 mg contained inside the outer injection device. Detailed instructions for use can be found on the outside of the Twinject autoinjector.

Regardless of the autoinjector brand utilized, the technique is the same. Find the anterior-lateral thigh musculature. Although patients are instructed that they can self-administer an epinephrine autoinjector through clothing, EMS professionals should expose the skin and quickly cleanse the injection site with either an alcohol wipe or skin disinfectant wipe/swab prior to injection. The autoinjector should be firmly depressed against the skin until activated. Be sure to maintain pressure on the autoinjector to avoid a recoil and loss of medication from absorption as intended. Maintain the pressure for approximately 10 seconds if using EpiPen or follow the five-second countdown voice prompt if using Auvi-Q/Allerject. Massage the injection site for approximately 30 seconds after the injection is complete to further speed medication uptake.

While a majority of anaphylaxis patients can be successfully treated with a single appropriate dose of epinephrine, 25% of these patients will require two or more doses of epinephrine, dosed 5–15 minutes apart for effective stabilizing treatment. Continue to closely assess the patient after epinephrine autoinjector dosing and be prepared for re-dosing if the patient doesn’t improve.