GasGasGas - The FRCA Primary Exam Podcast Gas Gas Gas - Comparing Volatiles
Nov 11, 2024
Explore the intriguing world of volatile anaesthetics and learn about their unique properties. Discover the significance of saturated vapour pressure and boiling points in relation to vapourisers. Compare the global warming potential of different agents and their physiological effects on patients. Delve into the merits of agents like isoflurane, sevoflurane, and desflurane, including their blood-gas solubility differences. Gain practical tips for memorizing key values for your future exams!
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Shared Pharmacologic Effects With Degree Variations
- Volatile anaesthetics share many core effects: blood pressure reduction, bronchodilation, cerebral blood flow increase, and MH trigger risk.
- Differences lie in degree (e.g., desflurane raises ICP most; sevoflurane least).
SVP vs Boiling Point Explained
- Saturated vapour pressure (SVP) is the vapour partial pressure when evaporation and condensation equilibrate above a liquid.
- Boiling point is when vapour pressure equals ambient pressure and bubbles form throughout the liquid.
Blood:Gas Solubility Predicts Speed
- Blood:gas solubility predicts onset/offset; lower values give faster induction and recovery.
- Desflurane (0.45) and sevoflurane (0.69) are faster than isoflurane (1.4).