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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}, {{AJL}} {{Alison}}
|QuestionAuthor= {{SSK}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
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|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Neurology
|SubCategory=Neurology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
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|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Neurology
|SubCategory=Neurology
|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?
|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?
 
|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.
|Explanation=[[Malignant hyperthermia]], a condition characterized by a severe reaction frequently occurring under [[general anesthesia]], manifests with the exposure to certain anesthetic drugs and muscle relaxants in patients with prior susceptibility. There are no clinical features specific to [[malignant hyperthermia]], but early signs typically include tachycardia and tachypnea, progressing to hyperthermia, generalized muscle rigidity, oliguria, and arrhythmia. Without rapid intervention, [[malignant hyperthermia]] can lead to death. [[Dantrolene]], frequently used in treatment of [[malignant hyperthermia]], depresses excitation-contraction coupling in skeletal muscles by binding to the ryanodine receptor, and decreasing free intracellular calcium concentration.
|AnswerA=Enflurane
 
|AnswerAExp=Enflurane is an inhaled anesthetic that can cause malignant hyperthermia. It has no role in the treatment of malignant hyperthermia.
 
|EducationalObjectives= [[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. Without intervention, [[malignant hyperthermia]] is often fatal.
|References= Hopkins PM. Malignant hyperthermia: advances in clinical management and diagnosis. Br J Anaesth. 2000;85(1):118-28.
 
|AnswerA=Succinylcholine
|AnswerAExp=[[Succinylcholine]], a muscle relaxant, can result in [[malignant hyperthermia]].
|AnswerB=Dantrolene
|AnswerB=Dantrolene
|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.
|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.
|AnswerC=Etomidate
|AnswerC=Etomidate
|AnswerCExp=[[Etomidate]], an anesthetic agent, can cause [[malignant hyperthermia]].
|AnswerCExp=Etomidate is anesthetic agent that can cause malignant hyperthermia. It has no role in the treatment of malignant hyperthermia.
|AnswerD=Physostigmine
|AnswerD=Physostigmine
|AnswerDExp=[[Physostigmine]], a reversible cholinesterase inhibitor, has no role in the treatment of [[malignant hyperthermia]].
|AnswerDExp=Physostigmine is a reversible cholinesterase inhibitor. It has no role in the treatment of malignant hyperthermia.
|AnswerE=Pralidoxime
|AnswerE=Pralidoxime
|AnswerEExp=Pralidoxime, a sympathomimetic drug used in the treatment of organophosphate poisoning, has no role in the treatment of [[malignant hyperthermia]].
|AnswerEExp=Pralidoxime is a sympathomimetic drug used in the treatment of organophosphate poisoning. It has no role in the treatment of malignant hyperthermia.
|EducationalObjectives=Dantrolene is the treatment of choice in malignant hyperthermia.
|References=Hopkins PM. Malignant hyperthermia: advances in clinical management and diagnosis. Br J Anaesth. 2000;85(1):118-28.<br>
First Aid 2015 page 498
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=Dantrolene, Pancuronium, Malignant hyperthermia, anesthesia, adverse reaction, muscle relaxent, anestthetic agent
|WBRKeyword=Dantrolene, Succinylcholine, Malignant hyperthermia, Anesthesia, Anesthesiology, Antidote, Adverse effect
|Approved=Yes
|Approved=Yes
}}
}}

Latest revision as of 00:25, 28 October 2020
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.
References: Hopkins PM. Malignant hyperthermia: advances in clinical management and diagnosis. Br J Anaesth. 2000;85(1):118-28.
First Aid 2015 page 498]]

Approved Approved::Yes
Keyword WBRKeyword::Dantrolene, WBRKeyword::Succinylcholine, WBRKeyword::Malignant hyperthermia, WBRKeyword::Anesthesia, WBRKeyword::Anesthesiology, WBRKeyword::Antidote, WBRKeyword::Adverse effect
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