A nurse is assessing a school-age child prior to administering digoxin. For which of the following findings should the nurse withhold the medication?

A. Oxygen saturation 88%: Low oxygen saturation indicates hypoxemia, which may be related to the child’s underlying cardiac condition but is not a direct contraindication for administering digoxin. The priority concern with digoxin is its cardiac effect. B. Heart rate 64/min: Digoxin slows the heart rate, and bradycardia is a key sign of toxicity. In school-age children, the medication should be withheld if the heart rate is below 70/min. A heart rate of 64/min meets this threshold, so withholding the drug is appropriate. C. Respiratory rate 18/min: A respiratory rate of 18/min is within the normal range for a school-age child (approximately 18–30/min). This finding does not warrant withholding digoxin. D. Urine output 25 mL/hr: While a low urine output can be a sign of poor renal perfusion, which can be a sign of worsening heart failure, it is not a direct contraindication for administering digoxin.