A child with Tetralogy of Fallot has a hypercyanotic spell (tet spell). Which combination of manoeuvres is MOST effective in terminating the spell?

• A Knee-chest position + IV morphine + IV propranolol ✓
• B Oxygen alone + IV digoxin
• C IV furosemide + supine position
• D IV atropine + IV noradrenaline

Explanation

Tet spells result from dynamic infundibular spasm causing increased right-to-left shunting. The knee-chest (squatting) position increases systemic vascular resistance (SVR) by kinking the femoral arteries, reducing right-to-left shunting. Morphine suppresses the respiratory center hyperpnea, reduces infundibular spasm, and relieves catecholamine-driven spasm. Propranolol (IV/oral) reduces heart rate and infundibular contractility. Oxygen supplementation helps but is insufficient alone. Furosemide is not indicated and may worsen by reducing preload. Atropine would worsen tachycardia.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.