Peanut, tree-nut and seed allergy — formative SAQs

SAQ 1 (10 marks)

A 5-year-old boy with known peanut allergy and asthma develops facial urticaria, wheeze and abdominal pain within five minutes of eating a biscuit at a birthday party. His mother gives an antihistamine. Fifteen minutes later he is pale and drowsy with stridor. ^[12]

1. State your diagnosis and give the immediate pharmacological treatment, including dose, route and site. (3) ^[12]
2. List four adjuncts to the first-line agent and the correct positioning for this child. (3) ^[12]
3. Explain why asthma increases this child's risk of a fatal reaction and state the observation period you would recommend after recovery. (4) ^[12]

Model answer — SAQ 1

1. Anaphylaxis. The immediate treatment is intramuscular adrenaline into the anterolateral thigh (vastus lateralis), at approximately 0.01 mg/kg, repeated every five minutes if features persist; the antihistamine was an inappropriate first step and delayed definitive treatment. ^[12]

2. Adjuncts include high-flow oxygen, intravenous fluid boluses for shock, nebulised salbutamol for persistent bronchospasm, and an H1 antihistamine for urticaria. Position the child supine with legs elevated (left lateral if vomiting), because sitting a shocked child up can be fatal. ^[12]

3. Uncontrolled asthma is the strongest comorbid predictor of fatal food-induced anaphylaxis, both by compounding respiratory compromise and by reflecting undertreated airway inflammation. He requires a prolonged period of observation for biphasic recurrence — at least four to six hours, and admission if severe features or poor asthma control persist — and a plan review including two autoinjectors. ^[12]