During a cyanotic spell in Tetralogy of Fallot, which action best relieves the spell by increasing systemic vascular resistance?

During a cyanotic spell in Tetralogy of Fallot, which action best relieves the spell by increasing systemic vascular resistance?

• A. Placing in knee-chest position
• B. Placing the child in prone position
• C. Encouraging crying
• D. Administering oxygen

Answer: (A)

During a cyanotic spell in Tetralogy of Fallot, the primary issue is an increased right-to-left shunt caused by infundibular (RVOT) obstruction. Pushing blood toward the lungs by raising systemic vascular resistance reduces that shunt, allowing more blood to reach the lungs for oxygenation. The knee-chest position achieves this by elevating SVR and returning more venous blood to the heart, which improves preload and stabilizes circulation, helping to rapidly lessen cyanosis. Other actions don't modify the shunt as effectively. A prone position doesn't raise SVR. Encouraging crying worsens the spell by increasing oxygen demand and can worsen the cyanosis. Administering oxygen helps with oxygen content but doesn't as reliably increase SVR to lessen the right-to-left shunt.

During a cyanotic spell in Tetralogy of Fallot, the primary issue is an increased right-to-left shunt caused by infundibular (RVOT) obstruction. Pushing blood toward the lungs by raising systemic vascular resistance reduces that shunt, allowing more blood to reach the lungs for oxygenation. The knee-chest position achieves this by elevating SVR and returning more venous blood to the heart, which improves preload and stabilizes circulation, helping to rapidly lessen cyanosis.

Other actions don't modify the shunt as effectively. A prone position doesn't raise SVR. Encouraging crying worsens the spell by increasing oxygen demand and can worsen the cyanosis. Administering oxygen helps with oxygen content but doesn't as reliably increase SVR to lessen the right-to-left shunt.