3. Allergy Flashcards
In a patient reporting allergy (e.g., to food, to medications, environmental), ensure that the patient has the appropriate medication to control symptoms, such as ?
- antihistamines
- bronchodilators
- steroids
- EpiPen
Prescribe what to every patient who has a history of, or is at risk for, anaphylaxis ?
Epipen
Advise patients with any known drug allergy or previous major allergic reaction to get a what?
MedicAlert bracelet.
In the particular case of a child with an anaphylactic reaction to food, do what? (2)
- Prescribe an EpiPen for the house, car, school, and daycare.
- 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.
In a patient with unexplained recurrent respiratory symptoms, include allergy, include what in the DDX?
- Syndrome du bâtiment malsain
- Allergie saisonnière
Differenciate Type A and B drug reaction
- Type A - Adverse reaction
- Type B - Hypersensitivity
Describe Type 1 : Immunologic/Drug allergy
- Immediate IgE (mast cells +/- basophils)
- Within 30mins-1h
- Urticarial rash, pruritus, flushing, angioedema, wheezing, GI symptoms, hypotension
- Anaphylaxis is most severe type of presentation
Describe Type 2 : Immunologic/Drug allergy
- Delayed antibody (IgG) mediated cell destruction
- Usually 5-8d after exposure
- Anémie hémolytique, thrombocytopénie, neutropénie
Describe Type 3 : Immunologic/Drug allergy (6)
- Delayed IgG:drug immune complex deposition and complex activation
- Usually 1-2 weeks after exposure
- May have low complement, high ESR
- Maladie sérique (fever, urticarial/purpuric rash, arthralgia, acute glomerulonephritis (eg. antitoxin))
- Vasculitis - palpable purpura/petechiae, often lower extremities (eg. penicillins, cephalosporins, sulfonamides, phenytoin, allopurinol)
- Réaction d’Arthus - localized skin inflammation, necrosis (post-vaccine)
Describe Type 4 : Immunologic/Drug allergy (6)
- ** Delayed T-cell mediated**
- >48h, usually days-weeks after exposure (but <24h upon re-exposure)
- SJS/TEN
- DRESS
- Other: Contact dermatitis, maculopapular eruptions
Describe Physical Examination : Allergy
- ABC, Vitals (Hypotension, tachycardia)
- CVS
- Resp
- Abdominal exam
- Skin
Describe : Management of Anaphylaxis (5)
- ABC, vitals, monitors, IV x2, oxygen
- Epinephrine 0.5mg IM mid-antero-lateral thigh q5mins x3 doses
- Aggressive fluid resuscitation
- Salbutamol for bronchospasm in saline via nebulizer (or 5-10 puffs MDI with spacer), repeat PRN
- Adjunctive : Antihistamine (Diphenhydramine), Glucocorticoids (Methylprednisolone, Prednisone)
- Observation period for biphasic reactions (incidence of 20%, can occur up to 6 days)
Describe observation period
Although most guidelines suggest 4, 6 or 24h of observation there is no data to suggest this improves outcomes
Consider discharge in patients with prompt and complete symptom resolution
Consider observation if
* Risk factors (Previous biphasic, asthma)
* Severe features (Refractory hypotension, laryngeal edema, and respiratory compromise)
* Delayed or suboptimal treatment
If not improved with anti-histamine treatment in anaphylaxis, consider what ?
envisager un angio-œdème médié par la bradykinine
* Traiter avec de l’acide tranexamique (Cyklokapron) 1 g IV
* plasma frais congelé (2 unités),
* un concentré d’inhibiteur C1
Describe investigations : Anaphylaxis
- Les taux sériques de tryptase mesurés 15 à 180minutes après l’apparition des symptômes peuvent étayer le diagnostic.. Comparer à la tryptase de base améliore la précision
- Si aucune cause n’est identifiée, exclure un trouble des mastocytes
