A nurse is monitoring a client who is receiving intravenous heparin for angina and has a history of atrial fibrillation. Which of the following laboratory tests should the nurse use to evaluate the effectiveness of heparin therapy?

Drinking 8 oz nonfat milk daily: Nonfat milk is low in fat and calories and is often recommended as part of a healthy diet that can help manage blood pressure. This action does not increase the risk of hypertension.

Eating popcorn at the movie theater: While movie theater popcorn can be high in salt and unhealthy fats, eating it occasionally in moderation may not significantly impact blood pressure. However, a regular high-sodium diet could contribute to hypertension.

Walking 1 mile daily at 12 min/mile pace: Regular physical activity like walking can help lower blood pressure and reduce the risk of hypertension. This is a positive action that helps in managing and preventing hypertension.

Consuming 36 oz beer daily: Consuming alcohol in large quantities regularly can lead to increased blood pressure and is a known risk factor for developing hypertension. 36 ounces of beer daily is a significant amount and could contribute to high blood pressure and other health issues.

Activated partial thromboplastin time (aPTT) is the laboratory test that the nurse should use to evaluate the effectiveness of heparin therapy.Heparin is an anticoagulant that works by helping antithrombin inactivate thrombin and factor Xa, reducing the production of fibrin and thus decreasing the formation of clots.The aPTT measures the time it takes for a clot to form in a sample of blood after adding certain substances.The normal range for aPTT is 25 to 35 seconds.A therapeutic level of heparin is 1.5 to 2.5 times the normal value, or 46 to 70 seconds.

Choice A is wrong because prothrombin time (PT) is a test that measures the time it takes for a clot to form in a sample of blood after adding tissue factor.PT is used to monitor warfarin therapy, not heparin therapy.The normal range for PT is 11 to 13 seconds.

Choice B is wrong because international normalized ratio (INR) is a standardized way of reporting the PT results, taking into account the variations in different laboratories and reagents.INR is also used to monitor warfarin therapy, not heparin therapy.The normal range for INR is 0.8 to 1.2.

Choice D is wrong because platelet count is a test that measures the number of platelets in a sample of blood.Platelets are cell fragments that help with blood clotting by sticking together and forming a plug at the site of injury.Platelet count is not directly related to heparin therapy, although heparin can cause a rare but serious adverse effect called heparin-induced thrombocytopenia (HIT), which is a drop in platelet count due to an immune reaction that leads to excessive clotting.The normal range for platelet count is 150,000 to 400,000/mm3.