A nurse is teaching a client who takes warfarin daily. Which of the following statements by the client indicates a need for further teaching?

Choice A reason: Warfarin PO is not a suitable medication for DVT prophylaxis in the immediate postoperative period, as it has a slow onset of action and requires frequent monitoring of the INR (international normalized ratio). Warfarin may be used for long-term anticoagulation, but it is not effective for preventing the formation of new clots.

Choice B reason: Enoxaparin subcutaneous is a suitable medication for DVT prophylaxis in the immediate postoperative period, as it has a rapid onset of action and does not require frequent monitoring of the coagulation status. Enoxaparin is a low-molecular-weight heparin that inhibits the formation of thrombin and prevents the growth of existing clots.

Choice C reason: Aspirin PO is not a suitable medication for DVT prophylaxis in the immediate postoperative period, as it has a weak anticoagulant effect and may increase the risk of bleeding. Aspirin is an antiplatelet agent that inhibits the aggregation of platelets and prevents the formation of arterial clots, but it is not effective for preventing venous clots.

Choice D reason: Heparin infusion is not a suitable medication for DVT prophylaxis in the immediate postoperative period, as it requires continuous intravenous administration and frequent monitoring of the aPTT (activated partial thromboplastin time). Heparin is an unfractionated heparin that inhibits the formation of thrombin and prevents the growth of existing clots, but it has a narrow therapeutic window and a high risk of bleeding.

Choice A reason: A headache is not likely due to the anxiety about the chest pain, as anxiety usually causes other symptoms, such as palpitations, sweating, or trembling. A headache is more likely related to the vasodilating action of nitroglycerin, which causes increased blood flow to the brain.

Choice B reason: A headache does not indicate tolerance to the medication, as tolerance usually manifests as a reduced effect of the medication on relieving chest pain. A headache is more likely a sign of the medication's potency, as it indicates that the nitroglycerin is reaching the systemic circulation.

Choice C reason: A headache is an expected adverse effect of the medication, as nitroglycerin causes vasodilation of the cerebral vessels, which can result in increased intracranial pressure and pain. A headache is usually mild and transient, and can be relieved by taking analgesics, such as acetaminophen.

Choice D reason: A headache is not an indication of an allergy to the medication, as an allergic reaction usually causes other symptoms, such as rash, itching, swelling, or difficulty breathing. A headache is more likely a pharmacological effect of the medication, rather than an immunological response.