GasGasGas - The FRCA Primary Exam Podcast GasGasGas - Introduction to Local Anaesthetics
Jun 27, 2025
Dive into the fundamentals of local anaesthetics and discover how they work! Explore nerve anatomy and the intriguing process of sodium channel blockade. Learn about factors affecting drug onset, such as pKa and myelination, and why sensory blocks occur before motor ones. Unpack the differences between amide and ester anesthetics, along with their metabolic profiles. Plus, get informed about potential toxicities and emergency management techniques. It's an essential guide for anyone delving into anaesthesia!
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From Basic Knowledge To Clinical Depth
- Dr Gas Lurks recalls entering anaesthesia knowing only basic drug names and little nuance.
- He emphasises you will learn detailed local anaesthetic reasoning during training for clinical responsibility.
How Nerves Conduct Signals
- Nerve conduction relies on saltatory conduction via myelinated segments and nodes of Ranvier.
- Myelin thickness and axon diameter strongly determine conduction speed and drug susceptibility.
Sodium Channel Basics
- Voltage-gated sodium channels open at about -55 mV and peak near +40 mV during action potentials.
- Channels have open, closed and inactivated states and local anaesthetics target the internal channel pore.