A nurse is preparing to administer diphenhydramine to a client who is to receive a blood transfusion. The nurse should explain that the purpose diphenhydramine is to prevent which of the following manifestations of a transfusion reaction?

A) Antihistamines:
Antihistamines are commonly used in the treatment of allergic reactions, including anaphylaxis. They work by blocking the effects of histamine, which is released during an allergic reaction, and can help alleviate symptoms such as itching, hives, and nasal congestion. Antihistamines are typically included in the treatment regimen for anaphylaxis but should not be relied upon as the sole treatment.

B) Vasodilators.
Vasodilators are medications that widen blood vessels, leading to a decrease in blood pressure. In the context of anaphylaxis, where blood pressure can drop precipitously due to systemic vasodilation, the use of vasodilators can exacerbate hypotension, potentially worsening the patient's condition. Therefore, vasodilators should be avoided in the management of anaphylaxis.

C) Corticosteroids:
Corticosteroids, such as prednisone or methylprednisolone, are used in the management of anaphylaxis to reduce inflammation and prevent late-phase allergic reactions. They are not typically used as first-line treatment during the acute phase of anaphylaxis but may be administered after initial stabilization to prevent recurrence of symptoms.

D) Bronchodilators:
Bronchodilators, such as albuterol, are used to relieve bronchospasm and improve airflow in conditions such as asthma and chronic obstructive pulmonary disease (COPD). While bronchospasm can occur during anaphylaxis, bronchodilators may still be used to address this symptom. However, they should be used cautiously, and their administration should not delay the administration of epinephrine, which is the primary treatment for anaphylaxis.

A. Hypotension: Norepinephrine is administered to treat hypotension, so monitoring for hypotension is not typically a concern while the patient is receiving this medication. In fact, hypotension is often the reason for administering norepinephrine in the first place.

B. Liver failure: Monitoring for signs of liver failure may be important in patients receiving certain medications, but it is not a specific consideration when administering norepinephrine. Norepinephrine primarily affects blood pressure regulation and does not typically have direct effects on liver function.

C. Bradycardia: While norepinephrine can increase blood pressure by constricting blood vessels, it may also cause reflex bradycardia (a decrease in heart rate) as a compensatory response. However, the primary concern with norepinephrine administration is hypertension, not bradycardia.

D. Hypertension
Norepinephrine (Levophed) is a vasopressor medication commonly used to treat hypotension and shock. It works by constricting blood vessels, which increases blood pressure. Therefore, when administering norepinephrine, the nurse should monitor the patient for hypertension, as the medication's intended effect is to raise blood pressure.