WBR0393
| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::During a minor abdominal surgery, a patient receives an injection of succinylcholine to facilitate access to the surgical site by paralyzing his abdominal muscles. Several minutes after the injection is administered, the patient's heart rate increases to 135/min and his blood pressure to 182/99 mmHg. The monitor shows an increase in minute ventilation and end-tidal carbon dioxide. His core temperature also begins to increase steadily, reaching 41.2 ᵒC (106.1 ᵒF). Alerted by the patient's status, the anesthesiologist administers an intravenous agent to counteract the effects of the muscle relaxant. The patient's vitals slowly begin to stabilize. Which of the following intravenous agents did the anesthesiologist most likely administer to the patient?]] |
| Answer A | AnswerA::Enflurane |
| Answer A Explanation | AnswerAExp::Enflurane is an inhaled anesthetic 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 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, progressing 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::Yes |
| Keyword | WBRKeyword::Dantrolene, WBRKeyword::Succinylcholine, WBRKeyword::Malignant hyperthermia, WBRKeyword::Anesthesia, WBRKeyword::Anesthesiology, WBRKeyword::Antidote, WBRKeyword::Adverse effect |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |