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Hypercyanotic spell — MRCPCH FOP MCQ

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HardCardiologyHypercyanotic spellMRCPCH FOP

A 9-month-old girl with known tetralogy of Fallot becomes deeply cyanosed and irritable after crying. Oxygen saturation is 62%, she has a harsh systolic murmur and her knees are flexed towards her chest by the nurse. What is the most appropriate management?

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Correct answer: E — Knee-chest positioning, high-flow oxygen and urgent senior help

This is a hypercyanotic spell, requiring immediate measures to increase systemic vascular resistance and reduce right-to-left shunting. Propranolol may be part of prevention or specialist management but is not enough as initial care in a severe spell. Furosemide treats heart failure rather than dynamic outflow obstruction. The pearl is that knee-chest positioning is a practical temporising intervention while senior help arrives.

Reference: APLS; Paediatric cardiology consensus guidance