WBR0393
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::During a major abdominal surgery, a patient receives an injection of pancuronium, which paralyzes his abdominal muscles in order to facilitate access to the surgical site. Several minutes after the injection is administered, the patients experiences an increase in minute ventilation, carbon dioxide production, heart rate to 135 bpm, blood pressure to 182/99 mmHg, and core temperature to 41.2 °C. Troubled by the unstable vitals, the anesthesiologist administers a second intravenous agent to counteract the effects of the muscle relaxant. The patient's vitals stabilize soon after the second injection and he begins to defervesce. Which of the following intravenous agents did the anesthesiologist most likely administer to the patient?]] |
| Answer A | AnswerA::Succinylcholine |
| Answer A Explanation | AnswerAExp::Succinylcholine is a muscle relaxant that can cause malignant hyperthermia. It has no role in the treatment of malignant hyperthermia. |
| Answer B | AnswerB::Dantrolene |
| Answer B Explanation | AnswerBExp::Dantrolene is the treatment of choice for malignant hyperthermia. It acts by inhibiting excitation-contraction coupling in skeletal muscle by binding to the ryanodine receptor. |
| Answer C | AnswerC::Etomidate |
| Answer C Explanation | AnswerCExp::Etomidate is anesthetic agent that can cause malignant hyperthermia. It has no role in the treatment of malignant hyperthermia. |
| Answer D | AnswerD::Physostigmine |
| Answer D Explanation | AnswerDExp::Physostigmine is a reversible cholinesterase inhibitor. It has no role in the treatment of malignant hyperthermia. |
| Answer E | AnswerE::Pralidoxime |
| Answer E Explanation | AnswerEExp::Pralidoxime is a sympathomimetic drug used in the treatment of organophosphate poisoning. It has no role in the treatment of malignant hyperthermia. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Malignant hyperthermia is a condition characterized by a severe reaction, frequently occurring under general anaesthesia. It is a manifestation to the exposure to certain anesthetic drugs and muscle relaxants in patients with prior susceptibility to develop this condition. There are no clinical features specific for malignant hyperthermia. Typically, early signs include tachycardia and tachypnea, that progress to hyperthermia, generalized muscle rigidity, oliguria, arrhythmia and eventual death if treatment is not initiated. Recognition of early signs are important to warrant rapid intervention. Dantrolene is the medication of choice for the treatment of malignant hyperthermia. Dantrolene depresses excitation-contraction coupling in skeletal muscle by binding to the ryanodine receptor, and decreasing free intracellular calcium concentration. Educational Objective: Dantrolene is the treatment of choice in malignant hyperthermia. |
| Approved | Approved::No |
| Keyword | WBRKeyword::Dantrolene, WBRKeyword::Pancuronium, WBRKeyword::Malignant hyperthermia |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |