During a hypercyanotic spell in Tetralogy of Fallot, the child typically does what?

• A. Stand to breathe
• B. Squat down to breathe better
• C. Lie down completely for rest
• D. Cry loudly to increase oxygen

Answer: (D)

In a hypercyanotic spell from Tetralogy of Fallot, the main problem is a sudden increase in right-to-left shunting across the ventricular septal defect, which drops oxygen delivery to the body. The quickest way to counter this is to raise the systemic vascular resistance so more blood is directed toward the lungs rather than leaking across the VSD. Squatting or bringing the knees to the chest accomplishes this by increasing afterload, which reduces the shunt and improves pulmonary blood flow and oxygenation.

Standing would lower systemic vascular resistance and can worsen the cyanosis, while lying down doesn’t boost resistance, and crying increases intrathoracic pressure and oxygen demand without improving pulmonary blood flow. So the goal during a tet spell is to assume a squatting/knee-to-chest position to enhance oxygenation.