GasGasGas - The FRCA Primary Exam Podcast Gas Gas Gas - Suxamethonium
Dec 1, 2024
Dive into the fascinating world of suxamethonium! Discover its mechanism of action as it influences nicotinic receptors, leading to unique physiological effects. Learn about the metabolism by plasma cholinesterases and the associated risks like bradycardia and hyperkalaemia. Explore strategies to minimize adverse effects, including pre-curarization. The discussion also touches on malignant hyperthermia and important clinical dosing practices. Wrap it up with key takeaways for handling emergency scenarios!
AI Snips
Chapters
Transcript
Episode notes
How Suxamethonium Works
- Suxamethonium is a depolarising muscle relaxant that agonises nicotinic acetylcholine receptors and holds them open.
- It causes initial widespread fasciculations by subverting normal motor unit-mediated contraction.
Plasma Metabolism Limits Effect
- Plasma (pseudo)cholinesterases break suxamethonium down in plasma, not at the neuromuscular junction.
- Only ~20% of an IV dose reaches the junction and acts until it diffuses back to plasma for metabolism.
Dosing And Onset Practicalities
- Use 1–2 mg/kg IV (1.5 mg/kg commonly used) for RSI and expect onset ~30 seconds with 3–5 minute duration.
- Remember IM dosing is 2–4 mg/kg and small doses (0.1–0.5 mg/kg) break laryngospasm.