A postoperative patient who received an intravenous infusion of morphine has a respiratory rate of 8 breaths per minute and is lethargic. Which as-needed medication should the nurse administer to the patient?

Choice A rationale: Before administering lithium, the nurse should assess serum creatinine levels. Lithium is excreted by the kidneys, and impaired renal function can lead to lithium toxicity.
Choice B rationale: Serum troponin I and T levels are markers of cardiac damage and are not directly related to lithium therapy.
Choice C rationale: Fasting blood glucose level is not specifically related to the assessment needed before administering lithium.
Choice D rationale: Serum lipid profile is not directly related to the assessment needed before administering lithium.

Choice A rationale: Methylphenidate is a central nervous system stimulant, and excessive caffeine intake can exacerbate its stimulant effects. Consuming an unlimited number of cola soft drinks, which typically contain caffeine, is not advisable. The patient should be educated to moderate caffeine intake to avoid potential interactions and side effects.
Choice B rationale: Methylphenidate can interact with caffeine, so avoiding chocolate, coffee, and tea is a valid recommendation to prevent excessive stimulant effects.
Choice C rationale: Decaffeinated coffee still contains a small amount of caffeine, and patients taking methylphenidate should be aware of this to manage their overall caffeine intake.
Choice D rationale: Taking methylphenidate after breakfast is a common recommendation to minimize appetite suppression and potential weight loss associated with the medication.