Question

Patients administered sevoflurane and succinylcholine for abdominal surgery develops post-operative muscle rigidity. What is the drug of choice here?

• A. Dantrolene
• B. Diazepam
• C. Propranolol
• D. Paracetamol

Hint:

Malignant hyperthermia after succinylcholine or volatile anesthetics is treated with dantrolene.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
A patient develops muscle rigidity after exposure to specific anesthetic triggers: sevoflurane (volatile gas) and succinylcholine (muscle relaxant).
This classic clinical scenario describes Malignant Hyperthermia (MH), a life-threatening pharmacogenetic condition.
Step 2: Detailed Explanation:

Pathophysiology of Malignant Hyperthermia: MH is caused by a mutation in the Ryanodine Receptor (RYR1) in skeletal muscle. Triggering agents cause an uncontrolled, massive release of calcium from the sarcoplasmic reticulum.

Clinical Manifestations: This calcium flood leads to sustained muscle contraction (rigidity), hypermetabolism, rapid rise in temperature (hyperthermia), and metabolic acidosis.

Drug of Choice: The definitive treatment for an MH crisis is Dantrolene Sodium.

Mechanism of Dantrolene: Dantrolene is a skeletal muscle relaxant that works by directly binding to the RYR1 receptor. It blocks the release of calcium from the sarcoplasmic reticulum, thereby reversing the metabolic crisis.

Management Steps: Immediate treatment includes stopping all triggers, hyperventilating with 100% oxygen, and cooling the patient alongside the administration of intravenous Dantrolene.

Why not other options? Diazepam is a CNS-acting muscle relaxant and is ineffective in MH. Propranolol and Paracetamol only treat symptoms (tachycardia and fever) but do not address the underlying intracellular calcium defect.

Step 3: Final Answer:
Dantrolene is the only specific and life-saving antidote for Malignant Hyperthermia triggered by anesthetic agents.