Final answer:
The nurse should withhold the medication and contact the provider for bradycardia, a heart rate less than 60 beats per minute.
Step-by-step explanation:
Based on the information provided, the nurse should withhold the medication and contact the provider for bradycardia, which is a heart rate less than 60 beats per minute. A heart rate of 55/min falls below the normal range of 60-100 bpm for adults. While the client's blood pressure is slightly elevated, it is not a contraindication for the administration of digoxin. The respiratory rate of 20/min is within the normal range as well.