Insect-sting hypersensitivity — branching viva

Opening. Take me through how you recognise and manage this child in the first five minutes. ^[2]

Recognition. This is systemic anaphylaxis to a wasp sting — multisystem within minutes, with skin (flushing, lip and tongue swelling), respiratory (wheeze, distress) and early cardiovascular (dizziness) involvement. Up to a fifth of systemic sting reactions have no skin signs, so I would not wait for a rash. ^[2]

Immediate management. Call for help, remove any retained stinger by scraping sideways, lie him flat with legs raised because he is dizzy, give high-flow oxygen, and give intramuscular adrenaline into the anterolateral thigh — 300 micrograms, as he is around ten years and roughly 30 to 50 kilograms. Repeat every five minutes if no response, give an intravenous crystalloid bolus of 10 mL/kg for shock, and add an inhaled bronchodilator for refractory wheeze. ^{[1] [2]}

Branch — refractory. If he needs two or more adrenaline doses or remains shocked, escalate to an intravenous adrenaline infusion titrated to response. If he is on a beta-blocker and refractory to adrenaline, give glucagon. Manage refractory disease with senior or PICU support. ^[2]

Investigation. Anaphylaxis is clinical — treatment never waits for a test. I would arrange timed serum tryptase on arrival, at one to two hours, and at baseline at least twenty-four hours later. A normal acute tryptase never excludes venom anaphylaxis. ^[5]

Branch — tryptase and severity. Why does the baseline tryptase matter? Because the Ruëff data showed it is the strongest predictor of how severe the next sting will be, and an elevated value screens for clonal mast-cell disease (KIT D816V) — the severe-reactor phenotype. ^{[5] [9]}