A client with a history of atrial fibrillation is prescribed warfarin (Coumadin). Which laboratory test should the nurse monitor to determine the effectiveness of the medication?

Correct Answer: B

Rationale: The correct answer is B: Prothrombin time (PT) and international normalized ratio (INR). Warfarin works by inhibiting vitamin K-dependent clotting factors, affecting the PT and INR. Monitoring these levels helps assess the effectiveness of warfarin in preventing clot formation. Platelet count (A) assesses clotting ability but not the effectiveness of warfarin. Activated partial thromboplastin time (C) assesses intrinsic pathway clotting factors, not affected by warfarin. Fibrinogen level (D) assesses the final step of clot formation, not specific to warfarin effectiveness.

Correct Answer: B

Rationale: The correct answer is B: Encourage passive range-of-motion exercises. This intervention helps improve joint mobility, reduce stiffness, and alleviate pain in clients with rheumatoid arthritis. Passive range-of-motion exercises can prevent joint contractures and maintain joint function. Applying cold packs (A) may help reduce inflammation but does not address joint stiffness. Administering a muscle relaxant (C) is not typically indicated for rheumatoid arthritis. Providing a high-calorie diet (D) is important for overall health but does not directly address joint pain and stiffness in this case.

Correct Answer: C

Rationale: The correct answer is C: Moon face and buffalo hump. In Cushing's syndrome, excessive cortisol production leads to characteristic symptoms like moon face (round, puffy face) and buffalo hump (fat accumulation at the back of the neck). This is due to redistribution of fat in the body. Hyperpigmentation (choice A) is seen in Addison's disease, not Cushing's. Hypotension (choice B) is unlikely due to the cortisol-induced sodium retention. Weight loss (choice D) is less common in Cushing's due to the metabolic changes causing weight gain.

Correct Answer: B

Rationale: The correct answer is B: Serum potassium of 2.8 mEq/L. Hypokalemia can lead to life-threatening cardiac arrhythmias, especially in diabetic patients with hyperglycemia. Immediate intervention is needed to prevent cardiac complications. A: Serum glucose of 350 mg/dL is high but not immediately life-threatening. C: Serum sodium of 136 mEq/L is within normal range and does not require immediate intervention. D: Serum bicarbonate of 20 mEq/L is slightly low but does not pose an immediate risk to the patient's life.

Correct Answer: C

Rationale: The correct answer is C: Urine output of 20 ml/hour. In severe dehydration, decreased urine output indicates compromised renal function and impaired fluid balance, necessitating immediate intervention to prevent further complications. A: Heart rate of 110 bpm is elevated but not an immediate concern. B: Blood pressure of 90/60 mm Hg is low but may be compensated in dehydration. D: Dry mucous membranes are a sign of dehydration but not an immediate threat compared to inadequate urine output.