A nurse is reviewing the laboratory results of a client who is receiving unfractionated heparin for DVT.

Which of the following values indicates a therapeutic effect of heparin?

The correct answer is choice C. Administer low molecular weight heparin.Low molecular weight heparin is an anticoagulant drug that prevents the formation and growth of blood clots in patients at risk for VTE.It is recommended for patients undergoing hip replacement surgery as a pharmacological prophylaxis.

Choice A is wrong because applying sequential compression devices (SCDs) is not enough to prevent VTE in patients undergoing hip replacement surgery.SCDs are mechanical devices that improve blood flow in the legs by inflating and deflating around them.However, they are not as effective as anticoagulant drugs in reducing the incidence of VTE.

Choice B is wrong because encouraging early ambulation is not enough to prevent VTE in patients undergoing hip replacement surgery.Early ambulation is the act of walking soon after surgery to improve circulation and prevent complications.However, it is not associated with a lower risk of VTE compared to bed rest.

It may also be contraindicated in some patients depending on their surgical and medical conditions.

Choice D is wrong because elevating the affected leg above the level of the heart is not enough to prevent VTE in patients undergoing hip replacement surgery.Elevating the leg may help reduce swelling and pain, but it does not prevent clot formation or propagation.

Choice E is wrong because massaging the affected leg gently is not only ineffective but also harmful for preventing VTE in patients undergoing hip replacement surgery.Massaging the leg may dislodge existing clots and cause them to travel to the lungs, resulting in a life-threatening pulmonary embolism.

The correct answer is choice B. Activated partial thromboplastin time (aPTT) of 60 seconds.This value indicates a therapeutic effect of heparin because it is about two times the normal value of 25 to 35 seconds.Heparin produces its major anticoagulant effect by inactivating thrombin and factor Xa through an antithrombin-dependent mechanism.The APTT measures the intrinsic and common pathways of coagulation, which are affected by heparin.

Choice A is wrong because platelet count of 150,000/mm3 is within the normal range of 150,000 to 450,000/mm3.Heparin does not affect platelet count directly, but it can cause heparin-induced thrombocytopenia, a serious complication that reduces platelet count and increases the risk of thrombosis.

Choice C is wrong because prothrombin time (PT) of 12 seconds is within the normal range of 11 to 13.5 seconds.Heparin does not affect PT significantly because PT measures the extrinsic and common pathways of coagulation, which are not affected by heparin.

Choice D is wrong because international normalized ratio (INR) of 1.0 is within the normal range of 0.8 to 1.2.Heparin does not affect INR significantly because INR is a standardized measure of PT that reflects the activity of vitamin K-dependent factors, which are not affected by heparin.