A nurse is caring for a client who arrives at the emergency department and reports vomiting and diarrhea for the past 3 days. The client's serum potassium level is 2.8 mEq/L. Which of the following interventions should the nurse implement first?

A complete AV block (also called third-degree AV block) is a type of heart block in which there is no electrical communication between the atria and ventricles. This means that the atria and ventricles beat independently of each other, resulting in a slow and irregular pulse. A complete AV block can cause symptoms such as dizziness, fainting, chest pain, shortness of breath, and heart failure.

A permanent pacemaker is a device that sends electrical impulses to the heart to regulate its rhythm and prevent bradycardia (slow heart rate). A permanent pacemaker is indicated for clients with complete AV block and rates slower than 40/min or symptomatic bradycardia.

The other options are not indications for a permanent pacemaker. Vasovagal bradycardia is a temporary drop in heart rate and blood pressure caused by a stimulus that triggers the vagus nerve, such as pain, stress, or straining.

It usually resolves on its own or with simple measures, such as lying down or elevating the legs. Sinus tachycardia is a normal increase in heart rate in response to physical or emotional stress, such as exercise, fever, or anxiety. It usually does not require treatment unless it is caused by an underlying condition or causes symptoms.

Asymptomatic second-degree AV block is a type of heart block in which some of the electrical impulses from the atria are blocked from reaching the ventricles. It may not cause any symptoms or affect the overall heart rate. It may be benign or transient, or it may progress to a more serious type of heart block. It may require monitoring or medication, but not a permanent pacemaker unless it causes symptomatic bradycardia.

A mastectomy is a surgical removal of one or both breasts, usually done to treat breast cancer. The nurse should respect the client's autonomy and provide factual information about the procedure, its benefits and risks, and possible alternatives . The nurse should also assess the client's readiness to learn, address any concerns or fears, and offer emotional support . Telling the client to get a second opinion may imply that the nurse does not trust the surgeon or doubts the necessity of the procedure.

Telling the client that they will be cancer-free if they have the procedure may be false or misleading, as there may be residual cancer cells or recurrence after surgery. Giving the client a list of other people who had the same procedure may violate confidentiality and may not be helpful or relevant to the client's situation.