anaphylaxis Archives

Anaphylaxis can be broadly defined as a severe, life-threatening, generalized or systemic hypersensitivity reaction. Literature suggests that anaphylaxis is not always easily recognized in the Emergency Department (ED). One study indicates around 50% of cases being misdiagnosed and up to 80% do not receive appropriate first-line treatment.

Triggers

The most commonly identified triggers of anaphylaxis include food, drugs and venom, but it is important to note that 30% of the cases can be idiopathic. Among drugs, muscle relaxants, antibiotics, NSAIDs and aspirin are the most commonly implicated.

Which patients are at an increased risk of anaphylaxis severity and mortality?

Extremes of age

Co-morbid conditions (asthma, COPD, cardiovascular disease)

Concurrent use of beta-blockers and ACE inhibitors

While the overall prognosis of anaphylaxis is good, the key to avoiding adverse outcomes is by prompt recognition and initiation of appropriate interventions. Below are key points to guide your management of anaphylaxis in the ED.

Recognizing Anaphylaxis in the ED

Anaphylaxis reactions vary significantly in duration and severity and a single set of criteria will not identify all anaphylactic reactions. The World Allergy Organization (WAO) has suggested the following criteria to help ED physicians be more consistent in their recognition of anaphylaxis.

Anaphylaxis is highly likely when any one of the following three criteria is fulfilled

1. Acute onset of an illness (minutes to several hours) with involvement of the skin, mucosal tissue, or both (eg, generalized urticaria, itching or flushing, swollen lips-tongue-uvula) AND AT LEAST ONE OF THE FOLLOWING

Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
Reduced blood pressure or associated symptoms of end-organ dysfunction (eg. hypotonia [collapse], syncope, incontinence) OR

2. Two or more of the following that occur rapidly after exposure to a likely allergen for that patient (minutes to several hours)

Involvement of the skin-mucosal tissue (eg, generalized urticaria, itch-flush, swollen lips-tongue-uvula)
Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
Reduced blood pressure or associated symptoms (eg, hypotonia [collapse], syncope, incontinence)
Persistent gastrointestinal symptoms (eg, crampy abdominal pain, vomiting) OR

3. Reduced blood pressure after exposure to known allergen for that patient (minutes to several hours)

Infants and children: low systolic blood pressure (age-specific) or greater than 30% decrease in systolic blood pressure
Adults: systolic blood pressure of less than 90 mm Hg or greater than 30% decrease from that person’s baseline

Management Algorithm of Anaphylaxis in the ED

Key Points in Management

Early and prompt recognition of the anaphylaxis/severe allergic reaction is key to appropriate management. Anticipate deterioration of clinical status/airway and an early call for help.
Initial systematic assessment using an ABCDE approach. The most important step in the management of anaphylaxis is the early administration of epinephrine intramuscularly. Do not delay this step while securing IV access/airway. There are no absolute contradictions to the use of epinephrine in the management of anaphylaxis.
Be prepared for a surgical cricothyroidotomy especially in a patient who is rapidly deteriorating despite epinephrine.
In patients on beta-blockers, the key is to give glucagon 1mg - 3mg IV every 5 minutes and titrate for resolution of hypotension (be prepared for vomiting).
Remember that antihistamines and corticosteroids do NOT play a role in the management of the acute reaction.
Serum tryptase levels are elevated in anaphylaxis but diagnosis is clinical and laboratory tests are not helpful in acute settings.
Patients who respond to treatment and have complete resolution of symptoms can be discharged after an observation period of 4 – 8 hours. However, up to 20% of the patients can have a biphasic reaction, which usually occurs within 8 hours but has been reported to occur as far as 72 hours. Consider extended observation for patients who presented with protracted anaphylaxis, hypotension or airway management.
Patients with anaphylaxis due to insect stings or unknown/unavoidable triggers should be prescribed an epinephrine autoinjector pen on discharge and timely follow up with an allergist.

References and Further Reading

Rosen’s Emergency Medicine, Chapter 109, Allergy, Hypersensitivity and Anaphylaxis Pages 1418 –1429
Core EM – Anaphylaxis, Heidi Sher (https://coreem.net/core/anaphylaxis/)
First10EM – Management of severe anaphylaxis in the Emergency Department (https://first10em.com/2015/07/20/anaphylaxis/)
2015 Update: World Allergy Organization Anaphylaxis Guidelines (https://waojournal.biomedcentral.com/articles/10.1186/s40413-015-0080-1)

Cite this article as: Neha Hudlikar, UAE, "Anaphylaxis in a Nutshell," in International Emergency Medicine Education Project, January 31, 2020, https://iem-student.org/2020/01/31/anaphylaxis-in-a-nutshell/, date accessed: September 21, 2023

While recently experiencing eight incredible weeks of Emergency Medicine rotations, I was reviewing my approach to anaphylaxis. Coincidentally, there was a real case a few days later, and I found the following mnemonic useful. If you’re having trouble remembering the different components of management for adult cases of anaphylaxis in the emergency department, think of SAFE-BBOP!

This is not the exact order in which anaphylaxis should be approached, but it may facilitate memorizing commonly-used treatment modalities while learning and reviewing the general approach. The ABC algorithm should be applied first (see: https://iem-student.org/abc-approach-critically-ill/). Following the diagnosis of anaphylaxis, epinephrine should be administered promptly, as delayed administration has been associated with increased mortality (1-4).

SAFE BBOP

S - Steroids

Prednisone 50mg PO or methylprednisolone 125mg IV. Glucocorticoids are theoretically used to prevent a possible biphasic reaction; however, there is limited evidence for this.

A - Antihistamines (H1 and H2)

Ranitidine 150mg PO/50mg IV, Diphenhydramine 25-50mg PO/IV. Their use is based on studies of urticaria and should only be used as an adjunct therapy.

F - Fluids

Normal saline or Ringer’s lactate 1-2 L IV.

B - Beta-blocked

If a patient is on a beta-blocker and is refractory to the administered epinephrine, consider glucagon 1-5mg slow IV bolus over 5mins, followed by an infusion at 5-15mcg/min, titrated to effect.

B - Bronchodilators

For persistent bronchospasm despite epinephrine, an inhaled bronchodilator can be considered, such as salbutamol 2.5-5mg nebulized or 4-8 puffs by MDI with spacer q20 mins x 3. This is based on studies of acute asthma exacerbation and should only be used as an adjunct therapy.

O - Oxygen

Every patient, who is critically ill, requires supportive oxygen treatment.

P - Positioning

Recumbent position with lower extremity elevation (consider left lateral decubitus position for pregnant patients to prevent inferior vena cava compression).

As for disposition considerations, the SAFE system below was introduced by Lieberman et al. (2007) to recognize the four basic actions to address with patients prior to discharge from the emergency department (5).

Seek support
Allergen identification and avoidance
Follow-up for specialty care
Epinephrine for emergencies

For a detailed review of anaphylaxis definitions, signs and symptoms, refer to this great Life in the Fast Lane article: https://litfl.com/anaphylaxis/

References

Prince, B.T., Mikhail, I., & Stukus, D.R. (2018). Underuse of epinephrine for the treatment of anaphylaxis: missed opportunities. J Asthma Allergy, 11, 143-151.
Sheikh, A., Shehata, Y., Brown, S.G., & Simons, F.E. (2009). Adrenaline for the treatment of anaphylaxis: Cochrane systematic review. Allergy, 64(2), 204.
Simons, F.E. (2008). Emergency treatment of anaphylaxis. BMJ, 336(7654), 1141.
McLean-Tooke, A.P., Bethune, C.A., Fay, A.C., & Spickett, G.P. (2003). Adrenaline in the treatment of anaphylaxis: what is the evidence? BMJ, 327, 1332.
Lieberman, P.,Decker, W., Camargo, C.A. Jr., Oconnor, R., Oppenheimer, J., & Simons, F.E. (2007). SAFE: a multidisciplinary approach to anaphylaxis education in the emergency department. Ann Allergy Asthma Immunol 98(6), 519-23.