Correct Answer: C

Rationale: The correct statement to include when teaching a client about furosemide is that it may cause potassium levels to decrease. Furosemide is a loop diuretic that can lead to hypokalemia, emphasizing the importance of monitoring potassium levels. Option A is incorrect because furosemide is usually taken in the morning to prevent nighttime diuresis. Option B is incorrect as tinnitus, not ringing in the ears, is associated with furosemide use. Option D is wrong because while it is essential to monitor potassium levels, the client should be advised to consume foods high in potassium to prevent hypokalemia.

Correct Answer: B

Rationale: The correct answer is B. Phenytoin can decrease the effectiveness of oral contraceptives, so it is important to inform the client about this interaction. Using an additional form of contraception, such as a backup method, is recommended to ensure adequate protection against pregnancy. Choice A is incorrect because it lacks specificity about the decrease in effectiveness of oral contraceptives caused by phenytoin. Choice C is incorrect as it suggests stopping phenytoin use while using oral contraceptives, which is not the appropriate action. Choice D is incorrect as phenytoin is known to decrease, not increase, the effectiveness of oral contraceptives.

Correct Answer: B

Rationale: Yellow-tinged vision is a classic sign of digoxin toxicity due to its effect on the eyes. It can cause a yellow or green visual halo around objects. Bradycardia, constipation, and hypertension are not typical signs of digoxin toxicity. Bradycardia may be a sign of digoxin's therapeutic effect in heart failure, while constipation and hypertension are not commonly associated with digoxin toxicity.

Correct Answer: B

Rationale: The correct answer is B. Metformin should be taken with a full glass of water in the morning to improve absorption and prevent gastrointestinal upset. Choice A is incorrect because metformin is not typically taken at bedtime. Choice C is unrelated to metformin therapy. Choice D is incorrect because metformin is actually better absorbed when taken with or after meals.

Correct Answer: A

Rationale: The correct intervention for preventing pressure ulcers in a client at risk is to turn the client every 2 hours. This helps relieve pressure on bony prominences, improving circulation and preventing tissue damage. Using a donut-shaped cushion can actually increase pressure on the skin and worsen the risk of pressure ulcers. Elevating the head of the bed to 45 degrees is beneficial for preventing aspiration in some cases but does not directly address pressure ulcer prevention. Massaging reddened areas can further damage the skin and increase the risk of pressure ulcer development by causing friction and shearing forces.