Which drugs act on the sympathetic nervous system, which regulates blood pressure by controlling heart rate, cardiac output, vascular tone, and renin release?

Warfarin is an anticoagulant that prevents blood clots from forming or growing larger. It works by inhibiting the synthesis of vitamin K-dependent clotting factors in the liver. The INR (international normalized ratio) is a measure of how long it takes the blood to clot.The therapeutic range for INR depends on the indication for warfarin therapy, but for atrial fibrillation, it is usually between 2 and 3. An INR level of 3.5 is above the therapeutic range, which means the blood is too thin and the patient is at risk of bleeding. The nurse should hold the warfarin dose and notify the physician, who may order vitamin K to reverse the effects of warfarin.

Choice A) Administer vitamin K as ordered by physician is wrong because vitamin K is not indicated unless the physician orders it based on the patient’s condition and INR level.

Vitamin K is an antidote for warfarin overdose and can reverse its anticoagulant effects.

However, administering vitamin K without a physician’s order may cause the INR to drop below the therapeutic range and increase the risk of clotting.

Choice B) Administer heparin as ordered by physician is wrong because heparin is another anticoagulant that works by activating antithrombin, a natural inhibitor of clotting factors.

Heparin is used for acute treatment of thromboembolic disorders, such as deep vein thrombosis or pulmonary embolism.

It is not indicated for atrial fibrillation unless there is evidence of acute thrombosis.

Administering heparin to a patient with an elevated INR would increase the risk of bleeding.

Choice C) Administer warfarin as ordered by physician is wrong because warfarin is the cause of the elevated INR and should be withheld until the INR returns to the therapeutic range.

Continuing to administer warfarin would further increase the INR and the risk of bleeding.

The nurse should monitor the serum potassium level to determine the therapeutic effectiveness of carvedilol (Coreg), which is a beta-blocker that can lower the heart rate and blood pressure. Carvedilol can also cause hyperkalemia, which is a high level of potassium in the blood that can lead to cardiac arrhythmias and muscle weakness.Therefore, the nurse should monitor the serum potassium level and report any values above 5.0 mEq/L to the provider.

Choice B) Serum sodium level is wrong because carvedilol does not affect the sodium level significantly.Sodium level is more relevant for diuretics, which can cause hyponatremia (low sodium) or hypernatremia (high sodium) depending on the type and dose of the medication.

Choice C) Serum magnesium level is wrong because carvedilol does not affect the magnesium level significantly.

Magnesium level is more relevant for digoxin, which is another medication used for heart failure that can cause hypomagnesemia (low magnesium) or hypermagnesemia (high magnesium).Hypomagnesemia can increase the risk of digoxin toxicity, while hypermagnesemia can decrease the effectiveness of digoxin.

Choice D) Serum calcium level is wrong because carvedilol does not affect the calcium level significantly.

Calcium level is more relevant for calcium channel blockers, which are another class of medications used for heart failure that can lower the heart rate and blood pressure by blocking the entry of calcium into the cardiac and vascular smooth muscle cells.

Calcium channel blockers can cause hypocalcemia (low calcium) or hypercalcemia (high calcium), which can affect the cardiac contractility and conduction.

The normal ranges for serum electrolytes are:

• Potassium: 3.5 to 5.0 mEq/L

• Sodium: 135 to 145 mEq/L

• Magnesium: 1.5 to 2.5 mEq/L

• Calcium: 8.5 to 10.5 mg/dL