Final answer:
Digoxin should be withheld from an infant if the pulse rate is below 60 beats/min, as this can indicate potential cardiac issues.
Step-by-step explanation:
When administering digoxin (Lanoxin) to an infant, the medication should be withheld and the physician notified if the pulse rate is below 60 beats/min. The pulse rate is a critical measure of a newborn's cardiovascular status, and for adults, a normal resting heart rate (HR) is between 60-100 bpm. Bradycardia is the term for a resting heart rate below 60 bpm, which can be a sign of cardiac distress. An infant's normal pulse rate is generally higher than an adult's, therefore, a pulse rate below 60 beats/min in an infant may indicate a serious condition needing medical attention.