Allergy – CSACI 2014 Guideline

1. In all patients, always inquire about any allergy and clearly document it in the chart. Re-evaluate this periodically.

The most common allergens include

  • certain foods – nuts, shell fish
  • insect stings (yellow jackets, hornets, wasps, honey bees).
  • Less common causes include
    • medications – penicillin
    • latex 
    • exercise.
  • Upon first exposure in individuals who are predisposed to allergy, the immune system rejects rather than tolerate the allergen. This process is called sensitization.
  • Re-exposure to the same allergen in the now-sensitized individual may result in an allergic reaction which, in its most severe form, is called anaphylaxis.

Pirority allergens (always be identified on food labels): ƒ

  • Sulfite (food additive)
  • Tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios, walnuts)
  • Milk, Egg, Peanut, Sesame, Soy,ƒ Wheat
  • Seafood,† Fish, e.g. trout, salmon, Shellfish
  • Crustaceans, e.g. lobster, shrimp, crab
  • Molluscs, e.g. scallops, clams, oysters, mussels,ƒ Mustard

Etiology:

Anaphylaxis ia an exaggerated immune mediated hypersensitivity reaction that leads to systemic histamine release, increased vascular permeability, and vasodilation.

  • Allergic – re-exposure to allergens: foods, stings, drugs, contrast media, blood products, latex
  • Non-allergic – eg. exercise induced

2. Clarify the manifestations of a reaction in order to try to diagnose a true allergic reaction (e.g., do not misdiagnose viral rashes as antibiotic allergy, or medication intolerance as true allergy).

Pseudo-allergy (“anaphylactoid”reaction)
  • looks like allergy but documented SE of med
  • i.e Vancomycin and Red man syndrome
  • Autoimmunity (meds causing lupus rxn), eg. Minocycline
  • can be type 4 reaction

Immunologic Reactions

  1. Type 1: Immediate onset (mins up to 1hr), IgE mediated
    • Urticaria, pruritis, angioedema of face, extremities, laryngeal structures, wheeze, GI sx, HoTN,
    • NO fever, no ↑CRP
  2. Type 2: Delayed onset (>1hr – 6hr to 5days), IgG medicated
    • Hemolytic anemia, thrombocytopenia, neutropenia
  3. Type 3: Delayed, Immune complex formation (IgG:drug) + complement activation
    • Serum sickness – fever, urticaria / purpura, arthralgias, acute glomerulonephritis, LN, ↓ Complement levels, ↑ESR
    • Vasculitis – palpable purpura / petechiae, fever, urticaria, arthralgias, LAD ↑ ESR, ↓ complement
    • drug fever
  4. Type 4: Delayed (48-72hr, days to weeks). T cell mediated (skin dominant)
    • Contact dermatitis – erythema, edema, vesicles/bullae
    • Subacute/chronic contact dermatitis – lichenification, erythema, scaling, morbiliform/maculopapular eruptions
    • SJS/TENS
    • Associated with viral infections – ↑ type 4 reaction during a viral illness or autoimmune dz exacerbation
      • eg. EBS with amoxil, CMS with abx, HHV6 with anticonvulsants, HIV with septra

Milk Protein Allergy

  • immune-mediated mucosal injury
  • Can present as:
    1. enterocolitis: vomiting, diarrhea, anemia, hematochezia
    2. Enteropathy: chronic diarrhea, hypoalbuminemia
  • Rx: Casein hydrosylate formula or remove milk protein from diet and BF

Anaphylaxis – Presentation

Anaphylaxis is a serious allergic reaction that is 1) rapid in onset – minutes up to hours 2) after exposure to an allergen and may cause death.

  • Symptoms of anaphylaxis generally include 3) two or more of the body systems. However, 4) low blood pressure alone in the absence of other symptoms, can also represent anaphylaxis.
    1. Skin: hives (anaphylaxis can occur without hives.) , swelling (face, lips, tongue), itching, warmth, redness
    2. Respiratory (breathing): coughing, wheezing, shortness of breath, chest pain or tightness, throat tightness, hoarse voice, nasal congestion or hay fever-like symptoms (runny, itchy nose and watery eyes, sneezing), trouble swallowing\
    3. Gastrointestinal (stomach): nausea, pain or cramps, vomiting, diarrhea
    4. Cardiovascular (heart): paler than normal skin colour/blue colour, weak pulse, passing out, dizziness or lightheadedness, shock
    5. Other: anxiety, sense of doom (the feeling that something bad is about to happen), headache, uterine cramps, metallic taste
  • The most dangerous symptoms of an allergic reaction involve breathing difficulties caused by
    • swelling of the airways (including a severe asthma attack in those who have asthma) or
    • a drop in blood pressure indicated by dizziness, lightheadedness, feeling faint or weak, or passing out.
  • At present, the severity of reactions cannot be predicted, but those with asthma, and who have had previous anaphylactic reactions are at increased risk.
  • Life threatening differentials for anaphylaxis include asthma and septic shok

3. In a patient reporting allergy (e.g., to food, to medications, environmental), ensure that the patient has the appropriate medication to control symptoms (e.g. antihistamines, bronchodilators, steroids, an EpiPen).


Acute Management:

In the event of a life-threatening allergic reaction / anaphylactic reaction, it is critical for individuals to respond quickly and appropriately by following these emergency steps:

  1. Prehospital
    • Give epinephrine auto-injector (e.g. EpiPen® or Allerject™) at the first sign of a known or suspected anaphylactic reaction. Tx immediately and aggressively
      • Epinephrine –The 1st line Tx for anaphylaxis – opens the airways, ↑BP & HR. It will not cause harm if given unnecessarily in healthy pt.
      • Antihistamines and asthma medications should not be used instead of epinephrine for treating
        anaphylaxis.
      • No person experiencing anaphylaxis should be expected to be fully responsible for self administration
        of an epinephrine auto-injector. Assistance from others, especially in the case of children, may be necessary.
    • Individuals with anaphylaxis who are feeling faint or dizzy because of impending shock should lie
      down unless they are vomiting or experiencing severe respiratory distress
    • Call 9-1-1 or local emergency medical services. Tell them someone is having a life-threatening allergic reaction.
    • Additional epinephrine should be available and give a second dose of epinephrine in 5 to 15 minutes after the first dose IF the reaction continues or worsens.
    • Transport to the nearest hospital immediately (ideally by ambulance) for evaluation & observation, even if symptoms are mild or have stopped. The reaction could worsen or come back, even after proper treatment.
  2.  Immediate ED initial Tx
    • 0.5ml of 1:1000 epi IM to lateral thigh (0.01ml/kg up to 0.4ml for children)
    • ABC, O2, IV, monitors
  3. Secondary Tx: po if tolerating oral meds
    • Observe in hospital (generally about 4-6 hours) & Prevent a delayed hypersensitivity reaction with adequate treatments (e.g., with steroids).
    • diphenhydramine (Benadryl) 50mg IM/IV q4-6h
    • Methylprednisolone 50-100mg IV / po prednisone
    • Salbutamol (Ventolin) neb if bronchospasm
  4. Disposition medications (allergy)
    • H1 antagonist: Cetirizine 10mg po daily or benadryl 50mg po daily x 3 days
    • H2 antagonist ranitidine 150mg po daily x 3 days
    • Corticosteroid: prednisone 50mg po daily x 5 days
    • Call emergency contact person (e.g. parent, guardian).
    • GP f/u in 24-48hr & discuss with pt about anaphylaxis management:
      • allergen avoidance strategies,
      • Rx an epinephrine autoinjector – Epipen 0.3mg / Epipen Jr – 0.15mg (<30kg) obtained immediately
      • referring them to an allergist for evaluation.

Out-pt Management

An individual is diagnosed as being at risk by obtaining a detailed personal history and confirmation of an allergy through appropriate investigations such as skin and/or blood tests. Once a diagnosis is made, a person should do the following:

  1. Avoid the allergenic substance
    1. Avoid Inset stings
      1. Keep garbage cans covered with tightly fitted lids in outdoor play areas
      2. Have insect nest professionally relocated or destroyed
      3. wear light colours and avoid loose flowing garments, shoes instead of sandals during the warm weather
      4. Avoid substances that attract insects: perfumes, scented lotions, cosmetics, hair sprays
      5. Drink from cups rather than beverage cans/bottles where insects can hide
      6. Consult with an allergist for venom immunotherapy, a de-sensitization program
    2. FOOD allergy avoidance
      1. Adult supervision of young children who are eating
      2. Individuals with food allergy ahould not trade or share food, food utensils, or food containers. When possible, young children with food allergies should eat in a designated area.
      3. School adm, parents and foodservice staff work together to ensure that food being served is appropriate
      4. The use of food in crafts & cooking classes may need to be modified or restricted depending on the allergies
      5. Alt to using food as a reward should be considered
      6. Ingredients of food brought in for special events by the school community, served in school cafeterias, or provided by catering should be clearly identified
      7. All children should be encouraged to comply with a “no eating” rule during daily travel on school buses
      8. All children should wash hands with soap and water before and after eating
      9. Surfaces such as tables, toys, etc should be carefully cleaned of contaminating foods.
  2. Carry an epinephrine auto-injector at all times Rx to every pt who has a hx or is at risk (allergic to food or stinging insects) for anaphylaxis
  3. Wear medical identification such as MedicAlert® identifies allergy
  4. Have a written Anaphylaxis Emergency Plan which describes the signs and symptoms of anaphylaxis and what to do in case of a reaction
  5. Receive instruction on a regular basis from their healthcare professional on when and how to use epinephrine auto-injectors. Anaphylaxis emergency plans should be reviewed and updated on a regular basis, e.g. once a year.

4. Prescribe an EpiPen to every patient who has a history of, or is at risk for, anaphylaxis.

5. Educate appropriate patients with allergy (e.g., to food, medications, insect stings) and their families about the symptoms of anaphylaxis and the self-administration of the EpiPen, and advise them to return for immediate reassessment and treatment if those symptoms develop or if the EpiPen has been used.

6. Advise patients with any known drug allergy or previous major allergic reaction to get a MedicAlert bracelet.

7. In a patient presenting with an anaphylactic reaction:
a) Recognize the symptoms and signs.
b) Treat immediately and aggressively.
c) Prevent a delayed hypersensitivity reaction through observation and adequate treatment (e.g., with steroids).

8. In patients with anaphylaxis of unclear etiology refer to an allergist for clarification of the cause

9. In the particular case of a child with an anaphylactic reaction to food:

  • a) Prescribe an EpiPen for the house, car, school, and daycare (Epipenx4).
  • 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.

Factors that may increase the risk of a severe anaphylactic reaction

  • Anaphylaxis and asthma
  • Under-utilized or delay in the use of epinephrine
    • No C/I using Epi for a life-threatening allergic reaction. Epi will not cause harm if given unnecessarily.
    • Possible s/e: rapid heart rate, pallor (paleness), dizziness, weakness, tremors and headache – generally mild and subside within a few minutes.
  • Underlying cardiac diseases
    • People with heart disease or HTN should speak to their physician about their cardiac medications and their need for epinephrine. Some medications (e.g. beta-blockers, ACE inhibitors) may interfere with the action of epinephrine and worsen the allergic reaction.
    • Use Glucagon 1mg IM if the pt takes beta-blockers
  • Previous history of anaphylaxis
    • a strong predictor of future anaphylaxis. However, >25% of adults and 65% of children presenting with anaphylaxis do not report a previous episode.
  • Age
    • The highest incidence in individuals aged 0 to 19 years. Food is the most common cause of anaphylaxis in children, adolescents and young adults.
    • In middle-aged and older adults, medications and insect venom are the most common causes.

10. In a patient with unexplained recurrent respiratory symptoms, include allergy (e.g., sick building syndrome, seasonal allergy) in the differential diagnosis.


Reference:
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Posted in 3 Allergy, 99 Priority Topics, FM 99 priority topics, Resp
One comment on “Allergy – CSACI 2014 Guideline
  1. ceej says:

    great topic! Unfortunately the link to the reference is not working.

    Like

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