A nurse is administering enoxaparin, a low-molecular-weight heparin, to a client who has undergone orthopedic surgery. The nurse should administer this medication by which route and at which site?

Subcutaneous injection in the abdomen.This is because enoxaparin is a low-molecular-weight heparin that is administered subcutaneously, usually in the abdomen or outer thigh.The drug should be clear and colorless or pale yellow.The dosage for adults is typically 30mg every 12 hours for 7 to 10 days, or 40mg once a day for 3 weeks after hip replacement surgery.The needle should be inserted fully into the skin and the syringe plunger should be pressed down to inject the drug.Injection sites should be rotated and areas of active skin disease or injury should be avoided.

Choice A is wrong because intramuscular injection in the deltoid muscle is not the recommended route or site for enoxaparin.Intramuscular injection may cause bleeding, bruising, or hematoma formation.

Choice C is wrong because intravenous infusion in a peripheral vein is not the recommended route for enoxaparin.Enoxaparin can be given intravenously only as a bolus injection for acute coronary syndrome, not as an infusion.

Choice D is wrong because intradermal injection in the forearm is not the recommended route or site for enoxaparin.Intradermal injection may cause skin irritation, infection, or necrosis.

The INR is a standardized measure of the prothrombin time (PT), which reflects the activity of the extrinsic and common pathways of coagulation.

Warfarin is an anticoagulant that inhibits the synthesis of vitamin K-dependent clotting factors (II, VII, IX, and X), which are involved in these pathways.

Therefore, the INR is used to monitor the effectiveness of warfarin therapy and adjust the dose accordingly.The target INR range depends on the indication for warfarin, but it is usually between 2 and 3.

Choice A is wrong because activated partial thromboplastin time (aPTT) reflects the activity of the intrinsic and common pathways of coagulation.

Heparin is an anticoagulant that enhances the activity of antithrombin, which inhibits factors II, IX, X, XI, and XII, which are involved in these pathways.Therefore, the aPTT is used to monitor the effectiveness of heparin therapy.

Choice C is wrong because platelet count measures the number of platelets in the blood, which are involved in primary hemostasis.Platelet count is not affected by warfarin therapy, but it can be decreased by heparin-induced thrombocytopenia (HIT), a rare but serious complication of heparin therapy.

Choice D is wrong because fibrinogen level measures the amount of fibrinogen in the blood, which is a precursor of fibrin, the main component of blood clots.Fibrinogen level is not affected by warfarin therapy, but it can be decreased by disseminated intravascular coagulation (DIC), a condition where widespread clotting and bleeding occur simultaneously.

The normal ranges for these tests are as follows:

• INR: 0.8 to 1.2

• aPTT: 25 to 35 seconds

• Platelet count: 150 to 450 x 10^9/L

• Fibrinogen level: 2 to 4 g/L