Final answer:
When caring for an infant with tetralogy of Fallot who experiences a hypercyanotic spell, the nurse should place the infant in a knee-chest position.
Step-by-step explanation:
The nurse should place the infant in a knee-chest position during a hypercyanotic spell. This position helps to increase vascular resistance and reduce the right-to-left shunt, thereby improving oxygenation. Hypercyanotic spells, also known as “blue spells,” occur when there is a sudden increase in the right-to-left shunting through the heart, leading to a decrease in the amount of oxygenated blood reaching the body. The knee-chest position brings the knees to the chest, which can help to alleviate this issue. This is a critical nursing intervention specific to the management of a hypercyanotic spell in infants with tetralogy of Fallot.