Final answer:
The nurse's priority should be the 3 episodes of vomiting in the infant, as this could indicate Digoxin toxicity, a critical condition requiring urgent attention.
Step-by-step explanation:
The nurse's priority when admitting a 4-month-old infant with heart failure who is prescribed Digoxin 0.5 mcg PO Q12H and Furosemide 20 mg PO Q12H would be to address option (c): '3 episodes of vomiting 6 wet diapers in 24 hr.' Vomiting in an infant with heart failure who is on Digoxin could signify Digoxin toxicity, which is a serious and life-threatening condition. This side effect of Digoxin needs immediate attention and possibly an adjustment in medication dosage. Moreover, adequate urine output is critical in a patient receiving diuretic therapy such as Furosemide, which is used to manage fluid balance in heart failure. While 6 wet diapers may seem sufficient, vomiting can lead to dehydration, further complicating the management of heart failure. Other options, such as mild temperature elevation and the consumption of concentrated formula, are important to monitor but are not as immediately concerning as potential Digoxin toxicity and dehydration.