All of the following are recognized triggering agents for malignant hyperthermia EXCEPT:

Explanation

## Triggering Agents in Malignant Hyperthermia **Key Point:** Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle triggered by exposure to certain anesthetic agents. Understanding which agents are safe and which are triggers is critical for perioperative management. ### Recognized Triggering Agents | Agent Category | Triggering | Safe | | --- | --- | --- | | **Depolarizing muscle relaxants** | Succinylcholine | — | | **Volatile anesthetics** | Isoflurane, Desflurane, Sevoflurane, Halothane | — | | **Inert gases** | — | Nitrous oxide | | **IV induction agents** | — | Propofol, Thiopental, Etomidate | | **Non-depolarizing relaxants** | — | Rocuronium, Vecuronium, Cisatracurium | | **Local anesthetics** | — | All safe (amide and ester) | **High-Yield:** The two main triggers are: 1. **Succinylcholine** — the only depolarizing agent; causes sustained muscle contraction and heat generation 2. **All volatile anesthetics** — isoflurane, desflurane, sevoflurane, and halothane are all triggers **Clinical Pearl:** Nitrous oxide is an inert gas and does NOT trigger MH. It is completely safe and can be used in susceptible patients. ### Pathophysiology of MH Triggering Triggers cause: - Abnormal calcium release from the sarcoplasmic reticulum (RYR1 or CACNA1S mutations) - Sustained muscle contraction (rigidity) - Hypermetabolism and heat generation - Rhabdomyolysis and subsequent complications (hyperkalemia, myoglobinuria, acute kidney injury) **Mnemonic: SAFE agents for MH-susceptible patients** = **S**uccinylcholine-**A**void, **F**ast IV induction (propofol/etomidate), **E**verything else (non-volatile, non-depolarizing) ### Safe Anesthetic Technique in MH-Susceptible Patients 1. Avoid succinylcholine and all volatile anesthetics 2. Use propofol or etomidate for induction 3. Use non-depolarizing muscle relaxants (rocuronium, vecuronium) 4. Nitrous oxide is safe and can be used 5. Use total IV anesthesia (TIVA) with propofol infusion 6. Use non-triggering local anesthetics for regional techniques 7. Ensure dantrolene is immediately available **Warning:** Do NOT confuse nitrous oxide with volatile anesthetics. Nitrous oxide is completely safe in MH-susceptible patients.