A 46-year-old woman complained of daytime sleepiness after taking an antihistamine for allergic rhinitis. Which of the following brain regions was most likely involved in the adverse effect of this drug?

Correct Answer: D

Rationale: The correct answer is D: Nucleus basalis of Meynert. The antihistamine likely caused sedation by blocking histamine receptors in the brain. The Nucleus basalis of Meynert is responsible for arousal and wakefulness, so blocking histamine receptors there can lead to daytime sleepiness. A: Nucleus tractus solitarius is involved in autonomic functions like blood pressure and heart rate regulation, not sedation. B: Caudatum is part of the basal ganglia involved in motor control and learning, not sedation. C: Hippocampus is crucial for memory and learning, not sedation.

Correct Answer: D

Rationale: The correct answer is D: Diazepam. Diazepam belongs to the benzodiazepine class of drugs, which can be addictive and have a high potential for abuse. For a patient with generalized anxiety disorder, long-term treatment with benzodiazepines like diazepam is generally discouraged due to the risk of tolerance, dependence, and withdrawal symptoms. Other choices (A, B, C) are commonly used for treating anxiety disorders without the same level of addiction potential as diazepam. Venlafaxine is an SNRI, Buspirone is a non-addictive anxiolytic, and Paroxetine is an SSRI.

Correct Answer: B

Rationale: The correct answer is B: Malignant hyperthermia. This disorder is characterized by a severe reaction to certain anesthesia drugs, leading to muscle rigidity, high fever, and potentially life-threatening complications. The patient's father likely experienced this disorder if he had a reaction during surgery. Acute intermittent porphyria (A) presents with abdominal pain and neuropsychiatric symptoms, not hyperthermia. Acute hepatitis (C) involves liver inflammation, not anesthesia reaction. Hemolytic anemia (D) is a condition where red blood cells are destroyed, not related to anesthesia.

Correct Answer: B

Rationale: The correct answer is B (Nitrous oxide 0.7; sevoflurane 0.6) for the minimum alveolar concentration for general anesthesia. The minimum alveolar concentration (MAC) is the concentration of an inhaled anesthetic at which 50% of patients do not respond to a standard surgical stimulus. In this case, a higher MAC value indicates a lower potency of the anesthetic. Therefore, higher MAC values for both nitrous oxide and sevoflurane mean that lower concentrations of these agents are needed to achieve general anesthesia. Choice B has higher MAC values for both drugs compared to the other options, making it the correct answer for providing appropriate general anesthesia with the minimum concentration of the drugs. Choices A, C, and D have lower MAC values for one or both drugs, which would require higher concentrations and potentially lead to inadequate anesthesia.

Correct Answer: D

Rationale: The correct answer is D: Tetracaine. Tetracaine is a local anesthetic that is least likely to cause methemoglobinemia in infants due to its minimal systemic absorption. Lidocaine, benzocaine, and bupivacaine have been associated with an increased risk of methemoglobinemia, especially in young infants. Lidocaine and bupivacaine are more systemically absorbed and can lead to higher levels of methemoglobin formation. Benzocaine is particularly risky in infants due to its association with methemoglobinemia. Tetracaine, on the other hand, has a lower systemic absorption rate and therefore poses a lower risk of causing methemoglobinemia in infants, making it the most appropriate choice for a 4-day-old boy with this condition.