WBR0393
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| 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 to facilitate access to the surgical site by paralyzing his abdominal muscles. Several minutes after the injection is administered, the patient's heart rate and blood pressure increase to 135 bpm and 182/99 mmHg. The monitor shows an increase in minute ventilation and carbon dioxide production. His core temperature also begins to increase steadily reaching 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.]] |
| 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 that describes a severe reaction usually occuring 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.
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| Approved | Approved::No |
| Keyword | WBRKeyword::Dantrolene, WBRKeyword::Pancuronium, WBRKeyword::Malignant hyperthermia |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |