Correct Answer: A

Rationale: Monitoring serum creatinine levels daily is the essential nursing action to prevent nephrotoxicity from aminoglycoside antibiotics. Aminoglycosides can cause kidney damage, so monitoring serum creatinine levels helps in detecting early signs of nephrotoxicity. Administering the antibiotic over a longer period of time (choice B) does not directly prevent nephrotoxicity. Encouraging increased fluid intake (choice C) is a general good practice but not specifically aimed at preventing nephrotoxicity. Restricting dietary protein intake (choice D) is not a direct preventive measure against aminoglycoside-induced nephrotoxicity.

Correct Answer: A

Rationale: The correct answer is A: Malignancy. A large, non-tender, hardened lymph node is a typical sign of malignancy and warrants further investigation. Choice B (Infection) is incorrect because typically in infections, lymph nodes are tender and may show signs of inflammation. Choice C (Benign cyst) is incorrect as a benign cyst would usually present as a soft, mobile lump. Choice D (Lymphadenitis) is incorrect as lymphadenitis usually presents with tender and enlarged lymph nodes due to inflammation.

Correct Answer: C

Rationale: An oxygen saturation of 85% is significantly low for a client with COPD and indicates hypoxemia, requiring immediate intervention. In COPD, the body's ability to oxygenate adequately is already compromised, so a saturation of 85% is particularly concerning. A barrel-shaped chest and use of accessory muscles are common findings in COPD due to chronic air trapping and increased work of breathing. While a respiratory rate of 28 breaths per minute is elevated, a low oxygen saturation is a more critical finding that necessitates prompt attention.

Correct Answer: D

Rationale: In this scenario, the nurse is dealing with a lethargic client with concerning vital signs after a PCA infusion of morphine sulfate. The next assessment the nurse should perform is to observe the amount and dose of morphine in the PCA pump syringe. This is crucial to evaluate for possible overdose, as the client's symptoms could be indicative of opioid toxicity. Checking the morphine amount and dose will help the nurse adjust the treatment accordingly. Choices A, B, and C do not directly address the potential cause of the client's lethargy and abnormal vital signs related to the morphine infusion.

Correct Answer: C

Rationale: The correct answer is C, International Normalized Ratio (INR). The INR should be closely monitored in a client receiving warfarin (Coumadin) to assess the effectiveness and safety of anticoagulation therapy. Monitoring the INR helps ensure that the client is within the therapeutic range for anticoagulation to prevent complications such as bleeding or clotting. Choices A, B, and D are incorrect. While monitoring electrolyte levels like serum potassium and sodium is important in overall client care, they are not specific to monitoring the effects of warfarin therapy. Prothrombin time (PT) is a component of INR and helps in monitoring warfarin therapy, but INR gives a standardized result that is independent of the laboratory method used, making it the preferred choice for monitoring warfarin therapy.