A 7-year-old child is brought to the clinic due to fatigue, slowed growth, and constipation. On examination, the child has dry skin, a puffy face, and a hoarse voice. Which of the following conditions should the nurse suspect?

A. Hydralazine is incorrect because it is an antihypertensive used to lower blood pressure in preeclampsia or eclampsia, but it does not reverse magnesium sulfate toxicity, which is the immediate concern given the symptoms of respiratory depression, oliguria, and absent deep tendon reflexes.

B. Methylergonovine is incorrect because it is a uterotonic used to control postpartum hemorrhage. It is not indicated for magnesium toxicity and would not address the life-threatening respiratory and neuromuscular effects of magnesium sulfate overdose.

C. Calcium gluconate is correct because it is the antidote for magnesium sulfate toxicity. Symptoms of toxicity include respiratory depression (RR <12), oliguria (<30 mL/hr), absent deep tendon reflexes, and eventually cardiac arrhythmias or arrest. Administering 10 mL of 10% calcium gluconate IV over 3–5 minutes can rapidly reverse neuromuscular and cardiac effects while supportive care (e.g., stopping magnesium infusion and monitoring) is continued.

D. Narcan is incorrect because it is an opioid antagonist used to reverse opioid overdose. It has no effect on magnesium sulfate toxicity and would not address the neuromuscular or respiratory compromise in this patient.

A. Prevent the return of oxygenated blood to the lungs is incorrect because closing the ductus arteriosus does not block pulmonary venous return. Blood still returns from the lungs to the left atrium and ventricle normally.

B. Decrease the edema in the legs and feet is incorrect because peripheral edema is not directly related to a patent ductus arteriosus (PDA). Edema is more associated with congestive heart failure or systemic venous congestion, which may be secondary but is not the immediate effect of surgical closure.

C. Stop the loss of unoxygenated blood to the systemic circulation is partially correct in theory, as a PDA can allow blood to shunt from the aorta to the pulmonary artery, but the key concern is left-to-right shunting of oxygenated blood back to the lungs, not unoxygenated blood going systemically.

D. Increase the oxygenation of blood is correct because surgical closure of a PDA eliminates the abnormal shunt that allows oxygenated blood from the aorta to flow back into the pulmonary circulation. This reduces pulmonary overcirculation and ensures that oxygenated blood remains in the systemic circulation, improving overall tissue oxygenation.