A nurse is reviewing laboratory results of a client who has atrial fibrillation and is taking warfarin. For which of the following results should the nurse notify the provider?

Choice A reason: Blood pressure 160/94 mm Hg is not a reason to withhold atenolol, as it is a beta-blocker that lowers blood pressure and reduces the workload of the heart. Atenolol is indicated for hypertension, angina, and arrhythmias. The nurse should administer atenolol as prescribed, unless the blood pressure is too low (hypotension).

Choice B reason: Heart rate 46/min is a reason to withhold atenolol, as it is a sign of bradycardia (slow heart rate), which can be a side effect of atenolol. Atenolol can decrease the heart rate by blocking the beta-1 receptors in the heart. The nurse should withhold atenolol if the heart rate is below 60 beats per minute or above 100 beats per minute, and report the finding to the provider.

Choice C reason: Oxygen saturation 95% is not a reason to withhold atenolol, as it is a normal value that indicates adequate oxygenation of the blood. Atenolol does not affect the oxygen saturation or the respiratory function. The nurse should monitor the oxygen saturation regularly, and report any signs of hypoxia (low oxygen level).

Choice D reason: Respiratory rate 18/min is not a reason to withhold atenolol, as it is a normal value that indicates normal breathing. Atenolol does not affect the respiratory rate or the respiratory function. The nurse should monitor the respiratory rate regularly, and report any signs of dyspnea (difficulty breathing).

Choice A reason: This is incorrect because extravasation is not related to the lifetime cumulative dose limit of doxorubicin, but to the leakage of the medication from the vein into the surrounding tissue. Extravasation can cause severe tissue damage and necrosis, and should be prevented by using a central venous catheter and monitoring the infusion site.

Choice B reason: This is incorrect because red tinged urine and sweat are not related to the lifetime cumulative dose limit of doxorubicin, but to the normal excretion of the medication from the body. Red tinged urine and sweat are expected side effects of doxorubicin and do not indicate toxicity or harm.

Choice C reason: This is correct because an excess amount of doxorubicin can lead to cardiomyopathy, which is a serious and potentially fatal complication of the medication. Cardiomyopathy is a condition in which the heart muscle becomes weak and unable to pump blood effectively. The risk of cardiomyopathy increases with the cumulative lifetime dose of doxorubicin, which should not exceed 450 to 550 mg/m2.

Choice D reason: This is incorrect because myelosuppression is not related to the lifetime cumulative dose limit of doxorubicin, but to the dose-dependent effect of the medication on the bone marrow. Myelosuppression is a condition in which the production of blood cells is reduced, leading to anemia, leukopenia, and thrombocytopenia. Myelosuppression can be managed by adjusting the dose and frequency of doxorubicin and monitoring the blood counts.