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Tet spell – knee-chest position — RACP Paediatrics MCQ

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EasyCardiologyTet spell – knee-chest positionRACP Paediatrics

A 4-month-old with known tetralogy of Fallot becomes deeply cyanotic and agitated during a blood test. SpO2 drops to 55%. The ejection systolic murmur has become softer. What is the most appropriate first intervention?

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Correct answer: D — Knee-chest positioning

Knee-chest positioning (squatting equivalent in infants) increases systemic vascular resistance and reduces venous return from the lower body, thereby reducing the right-to-left shunt and improving pulmonary blood flow. The softened murmur indicates reduced flow across the RVOT (more severe dynamic obstruction). This is the critical first step.

Reference: RCH Melbourne – 2023 – Tet Spell Management CPG; RACP Paediatric Curriculum – Cardiology