Correct Answer: C

Rationale: The nurse should monitor the aPTT (activated partial thromboplastin time) when caring for a client receiving Heparin therapy. The aPTT reflects the intrinsic pathway of the clotting cascade and is used to monitor the effectiveness of heparin, which primarily affects this pathway by potentiating antithrombin III. Monitoring the aPTT helps ensure that the client's blood is within the therapeutic range to prevent thrombus formation.

Correct Answer: B

Rationale: Atenolol is a beta-blocker that can cause bradycardia, leading to a decreased heart rate. Monitoring heart rate regularly is essential to detect any significant decreases promptly and seek medical attention. While other choices may be relevant to the client's overall health, monitoring heart rate is the priority instruction due to the nature of Atenolol's effects.

Correct Answer: B

Rationale: Warfarin is contraindicated for a client taking Gingko Biloba due to the potential interaction. Gingko Biloba can suppress coagulation and increase the risk of bleeding or hemorrhage when taken with anticoagulants like Warfarin.

Correct Answer: A

Rationale: To calculate the volume to administer, use the formula: Desired dose / Concentration = Volume to administer. In this case, (15,000 units / 20,000 units/mL) = 0.75 mL, which is rounded up to 0.8 mL. Therefore, the correct answer is 0.8 mL.

Correct Answer: A

Rationale: Bradycardia is a common sign of Digoxin toxicity. Digoxin, a medication used to treat heart conditions, can lead to toxicity manifesting as bradycardia. Monitoring the client's heart rate closely is crucial to detect potential toxicity early and prevent complications.