A nurse is caring for an infant experiencing a hypercyanotic, or "tet spell.”. Which interventions are appropriate for this condition?

Choice A rationale Hypercyanotic spells, or "tet spells," result from a sudden decrease in pulmonary blood flow and increased right-to-left shunting, leading to profound hypoxemia. Administering oxygen helps by slightly increasing arterial oxygen tension, which acts as a mild pulmonary vasodilator, potentially reducing pulmonary vascular resistance and improving oxygen delivery to tissues. This aims to counteract the immediate hypoxemia. Choice C rationale Morphine administration is appropriate because of its central nervous system depressant effects. It helps to calm the infant, decreasing systemic oxygen demands and reducing the hyperpnea (rapid, deep breathing) that often accompanies the spell. Furthermore, morphine mildly vasodilates, which increases systemic vascular resistance, decreasing the right-to-left shunt flow. Choice E rationale Placing the infant in the knee-chest position significantly increases systemic vascular resistance (SVR) by compressing the major arteries in the lower extremities. The increased SVR reduces the pressure gradient driving the right-to-left shunt through the ventricular septal defect, thereby increasing pulmonary blood flow and improving oxygen saturation during the hypercyanotic event.