CCFP Topic: Allergy & Anaphylaxis

This is mainly a concern in the context of anaphylaxis and drug allergy. However, food allergy and allergic rhinitis should be included in a full history.

First determine the allergen, document the reaction, when the reaction occurred and whether there has been exposure since the initial reaction that did not result in a repeat reaction.

Did you know that of patients who report a penicillin allergy, more than 80% have a negative response to penicillin skin testing. Further, 90% of adult inpatients tolerate penicillin upon further evaluation.

For Mild Intermittent Symptoms [BMJ Best Practice, 2020]

First Line

• Oral antihistamine, alongside allergy avoidance, or
• Intranasal antihistamine, with allergy avoidance

Second line

• Can combine therapies, or add
• Intranasal corticosteroids or leukotriene receptor antagonists

For Persistent Mild, or Moderate-Severe Intermittent Symptoms

First Line, In addition to oral and intranasal antihistamines, we consider intranasal corticosteroids.

We can also consider adding a couple adjuncts before going second line, such as

• Oral or intranasal decongestants but beware rebound rhinitis medicomentosa
• Nasal saline rinses

If response still isn’t sufficient then suggestion is to consider sublingual or subcutaneous immunotherapy.

For Persistent Moderate-Severe Symptoms

First line

• Intranasal corticosteroid and/or antihistamine, with a ton of adjuncts
• Adjuncts in this population include:
  • Intranasal ipratropium
  • Oral antihistamine
  • Oral or intranasal decongestant
  • Oral corticosteroid
  • Nasal saline irrigation

Second Line

• Sublingual or subcutaneous immunotherapy
  Not very common, and reserved for those not adequately responding to available pharmacotherapy and with an identifiable allergen trigger.

An epinephrine autoinjector should be provided to:

• All patients who have experienced anaphylaxis previously
• Those with any rapid-onset systemic allergic reaction (GI, resp, cardiac)
• Diffuse hives to any food or insect stings.
• Any rapid-onset reaction of any severity to the highest risk foods, such as peanut, tree nuts, fish and shellfish.

Most common allergens that cause anaphylaxis are foods and insect stings.

Common foods are:

•  peanuts,
• tree nuts
• milk,
• egg,
• sesame,
• soy,
• wheat,
• seafood,
• mustard.

“anaphylaxis emergency plan” from the Food Allergy Canada website

When discussing where to keep the EpiPen, ensure you show the parent and patient how to correctly and safely use the EpiPen. Also have them walk you through what you just taught them to ensure understanding. If possible, keep a sample autoinjector in your office for this teaching.

This costs $5/month. Provide medical details to MedicAlert, which are then available on a hotline 24/7 for paramedics and emergency responders to access if there is an emergency to help guide the care they provide.

a) Recognize the symptoms and signs.

Criteria 1: If no known exposure to an allergen, but there is rapid onset of skin or mucosal symptoms as well as either respiratory or cardiovascular compromise.

Criteria 2: If exposed to a likely allergen, two affected systems are required, but this can include the less common systems, such as GI.

Criteria 3: Hypotension after exposure to a known trigger. It is important to note that the definition of hypotension in children differs by age so consult an app, or have a look at the show notes.

b) treat immediately and aggressively

1. Have a posted, written emergency protocol for recognition and treatment of anaphylaxis.
2. Remove exposure to the trigger if possible.
3. ABCs, mental status, skin, and body weight, but don’t waste time here.
4. Call for help.
5. For adults: Epi 0.3 – 0.5 mg IM lateral thigh (EpiPen dose is 0.3 mg)

For children 0.01 mg/kg IM lateral thigh max of 0.3 mg IM per dose  (EpiPen Jr. is 0.15 mg). NIH in the states recommend adult dose if they weigh ≥25 kg.

5. No contraindications to Epi in context of anaphylaxis. 
6. Give IM q5-15min as necessary. Give the second dose at 5 minutes if no improvement after the first dose[1] .
7. Lie patient supine (unless resp compromise contraindicates it), elevate lower extremities, place pregnant patients on left side. Once patients supine, should not be allowed to sit up until fully stabilized due to risk of “empty ventricle syndrome”, which can cause large BP drop and death.
8. When indicated at any time, give high flow O2 (6-8 L/min) by face mask or oropharyngeal airway.
9. When indicated at any time, get IV access. When indicated, aggressive fluid replacement
10. If indicated CPR.
11. At frequent and regular intervals, BP, cardiac monitoring, resp status and oxygenation. Get ECG.

c) Prevent a delayed hypersensitivity reaction through observation and adequate treatment (e.g., with steroids).

 Up[1]  to 15% of anaphylaxis cases will have a biphasic response. No strong evidence to support use of corticosteroids to prevent biphasic reactions. Only theoretical. A recent non-randomized study suggested a NNT of 173-176. However, is often still given empirically.

Tintinalli’s disposition recommendations are:

• Patients who have received epinephrine should be observed, but the duration is not well established
  • Otherwise healthy pts who are symptom free after epinephrine can probably be safely discharged after 4 hours of event-free observation
  • Consider longer monitoring (even over 8 hrs) if:
    • Past hx of severe reactions
    • Those using B-blockers
    • Consider for pts who live alone, live far from care, have significant comorbidity, or are elderly
    • Others not from Tintinalli: asthma; multiple epi needed; airway edema, severe or prolonged symptoms.

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This is self explanatory. Treat as you would any other anaphylaxis. Make sure they go home with an epinephrine autoinjector.

a) Prescribe an EpiPen for the house, car, school, and daycare.

Patients should have at least two in common locations: home, backpack, school, daycare. A prescription is not required, but it’s more likely to be covered by insurance with a prescription.

The pediatric dosing is 0.15mg for patients <25kg, and 0.3mg for everyone over 25kg.

Expired EpiPens have between approximately 50-100% of the intended dose of epinephrine in them. So, if the only option at home is to give an expired EpiPen, advise patients that they can do this.

Simons, F. E. R., Ardusso, L. R. F., Bilo, M. B., El-Gamal, Y. M., Ledford, D. K., Ring, J., . . . World Allergy Organization. (2011). World allergy organization guidelines for the assessment and management of anaphylaxis. Journal of Allergy and Clinical Immunology, 127(3), e1-e22. doi:10.1097/WOX.0b013e318211496c

b) Advise the family to educate the child, teachers, and caretakers about signs and symptoms of anaphylaxis, and about when and how to use the EpiPen.

Foodallergycanada.ca has guidelines for the management and treatment of anaphylaxis in the community. Components of an anaphylaxis action plan: contact details, allergens/triggers, how to recognize signs and symptoms, medications prescribed and when they should be used. (aside from epi for anaphylaxis, can further instruct them, if applicable, to use any antihistamines prescribed for cutaneous symptoms and inhaled B-agonists for respiratory issues)

A 2001 study in the Journal of Allergy and Clinical Immunology gave epinephrine via multiple anatomical locations as well as IM v SC. They then measured the serum epinephrine levels.

A study in 2007 recruited 100 MDs and found that only two of them were able to complete all of the steps correctly. The most commonly issues were:

• not holding the pen in place for >5 seconds (57%),
• failure to apply pressure to activate (21%), and
• self-injection into the thumb (16%)

all patients receiving emergency epi must be transported to hospital immediately (ideally by ambulance) for evaluation and observation.

DO NOT FORGET TO CONSIDER ALLERGY for a patient presenting with recurrent respiratory symptoms.

Kanani, A., Betschel, S. D., & Warrington, R. (2018). Urticaria and angioedema. Allergy, Asthma & Clinical Immunology, 14(2), 59.

Small, P., Keith, P. K., & Kim, H. (2018). Allergic rhinitis. Allergy, Asthma & Clinical Immunology, 14(2), 51.

Sampson, H. A., Muñoz-Furlong, A., Campbell, R. L., Adkinson Jr, N. F., Bock, S. A., Branum, A., … & Gidudu, J. (2006). Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. Journal of Allergy and Clinical Immunology, 117(2), 391-397.

Simons, F. E. R., Ardusso, L. R. F., Bilo, M. B., El-Gamal, Y. M., Ledford, D. K., Ring, J., . . . World Allergy Organization. (2011). World allergy organization guidelines for the assessment and management of anaphylaxis. Journal of Allergy and Clinical Immunology, 127(3), e1-e22. doi:10.1097/WOX.0b013e318211496c

Simons, F. E. R., Gu, X., & Simons, K. J. (2000). Outdated EpiPen and EpiPen jrautoinjectors: Past their prime? The Journal of Allergy and Clinical Immunology, 105(5), 1025. doi:10.1067/mai.2000.106042

Warrington, R., Silviu-Dan, F., & Wong, T. (2018). Drug allergy. Allergy, Asthma & Clinical Immunology, 14(2), 60.

Waserman, S., Bégin, P., & Watson, W. (2018). IgE-mediated food allergy. Allergy, Asthma & Clinical Immunology, 14(2), 55.