ATI RN
Central and Peripheral Nervous System Drugs Questions
Question 1 of 5
Which of the following variables most likely caused the decrease in MAC in this case?
Correct Answer: D
Rationale: The correct answer is D: The addition of nitrous oxide. Nitrous oxide is known to decrease minimum alveolar concentration (MAC) of anesthetic agents, leading to a lower concentration needed to maintain anesthesia. This is due to its anesthetic properties and synergistic effects with other anesthetics. Choice A (cancer) and C (age) are unlikely to directly affect MAC levels. Choice B (use of two anesthetics) might actually increase MAC rather than decrease it, making it an incorrect choice.
Question 2 of 5
Which drug would most likely be effective in decreasing the patient's spontaneous breathing?
Correct Answer: B
Rationale: The correct answer is B: Vecuronium. Vecuronium is a non-depolarizing neuromuscular blocking agent that inhibits acetylcholine from binding to nicotinic receptors, leading to muscle paralysis including respiratory muscles, thus decreasing spontaneous breathing. Diazepam (A) is a benzodiazepine that acts on the central nervous system but does not directly affect respiratory muscles. Botulinum toxin (C) blocks acetylcholine release at the neuromuscular junction but is not suitable for systemic use to decrease spontaneous breathing. Dantrolene (D) is a muscle relaxant that acts on skeletal muscles but does not directly inhibit respiratory muscles.
Question 3 of 5
Which of the following structures was most likely the site of therapeutic action of botulinum toxin injected into the ocular muscles of the 22-year-old man with strabismus?
Correct Answer: B
Rationale: The correct answer is B: Somatic nerve terminals. Botulinum toxin acts by inhibiting the release of acetylcholine at the neuromuscular junction, leading to muscle paralysis. In the context of ocular muscles in strabismus, the toxin would target the somatic nerve terminals that innervate the extraocular muscles. This action results in the relaxation of the affected muscle, helping to correct the misalignment of the eyes. Choices A, C, and D are incorrect as they do not directly relate to the mechanism of action of botulinum toxin at the neuromuscular junction.
Question 4 of 5
Which of the following muscle relaxants was most likely given to a patient who exhibited transient muscle fasciculations that progressed to generalized paralysis within 1 minute of administration?
Correct Answer: B
Rationale: The correct answer is B: Succinylcholine. Succinylcholine is a depolarizing neuromuscular blocker that causes initial muscle fasciculations followed by flaccid paralysis within minutes. This pattern of transient fasciculations progressing to generalized paralysis aligns with the patient's symptoms. Cisatracurium (A) and Vecuronium (D) are non-depolarizing neuromuscular blockers that do not typically cause fasciculations. Dantrolene (C) is a skeletal muscle relaxant used to treat malignant hyperthermia and muscle spasticity, but it does not cause the rapid progression of paralysis described in the scenario.
Question 5 of 5
Which of the following adverse effects was most likely to occur in the patient receiving local injections of botulinum toxin for benign essential blepharospasm?
Correct Answer: D
Rationale: The correct answer is D: Eyelid ptosis. Botulinum toxin injections can weaken the muscles, leading to eyelid ptosis (drooping). This is a common adverse effect seen in patients receiving these injections for benign essential blepharospasm. Other choices are incorrect: A, retinal detachment, is not associated with botulinum toxin injections; B, visual hallucinations, are not a common side effect; C, visual loss, is not a typical adverse effect of botulinum toxin injections for blepharospasm.