Correct Answer: C

Rationale: Probably the most common cause of metabolic alkalosis is vomiting or gastric suction with loss of hydrogen and chloride ions. The disorder also occurs in pyloric stenosis in which only gastric fluid is lost. Vomiting, gastric suction, and pyloric stenosis all remove potassium and can cause hypokalemia.

Correct Answer: C

Rationale: Hair can be a source of infection and should be removed by clipping. Shaving the area can cause skin abrasions, and depilatories can irritate the skin.

Correct Answer: A

Rationale: Increased serum sodium causes increased thirst and the release of ADH by the posterior pituitary gland.

Correct Answer: B

Rationale: The correct answer is B. In elderly patients, fluid deficits can lead to confusion and cognitive impairment. Limiting fluids can disrupt the body's balance, leading to such symptoms. Adjusting the timing of fluids can help maintain hydration without causing nighttime interruptions. Choices A, C, and D are incorrect because they do not address the underlying issue of fluid imbalance causing confusion. Choice A suggests unnecessary hospital readmission and medication adjustments. Choice C incorrectly normalizes confusion post-surgery and suggests it is safe not to urinate at night, which can exacerbate the issue. Choice D inaccurately attributes confusion to sleep loss rather than fluid imbalance.

Correct Answer: D

Rationale: Hypokalemia often causes characteristic ECG changes, including an elevated U wave and flattened T waves.