Which drug increases the excretion of water and sodium by the kidneys, reducing blood volume and blood pressure?

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.

Digoxin (Lanoxin) is a cardiac glycoside that is used to improve the contractility of the heart and slow down the heart rate in patients with chronic heart failure. However, digoxin has a narrow therapeutic range and can cause toxicity if the dose is too high or if the patient has low potassium levels. A normal serum digoxin level is 0.5 to 2 ng/mL and a normal serum potassium level is 3.5 to 5 mEq/L. A low heart rate (less than 60 beats/min) is a sign of digoxin toxicity and the nurse should withhold the medication and report it to the provider. The nurse should also check the patient’s serum digoxin and potassium levels to determine if they are within normal limits.

Choice A is wrong because administering the medication as ordered could worsen the patient’s condition and increase the risk of digoxin toxicity.

Choice C is wrong because checking the patient’s serum digoxin level is not enough to prevent digoxin toxicity. The nurse should also check the patient’s serum potassium level and heart rate before giving digoxin.

Choice D is wrong because giving an additional dose of digoxin could cause a fatal overdose and lead to cardiac arrest. The nurse should never give more than the prescribed dose of digoxin without consulting the provider.