Anaesthesia Coffee Break Functional Residual Capacity (FRC) and how anaesthesia makes a mess of it!
Dec 20, 2020
Dive into the intriguing world of Functional Residual Capacity (FRC) and discover how anaesthesia dramatically alters it. Learn about crucial measurement methods and the interplay of anaesthetic, surgical, and patient factors influencing FRC. Find out why positioning and muscle tone loss matter, and explore the fascinating types of atelectasis arising from reduced FRC. Plus, uncover the implications of decreased FRC on breathing work and oxygen reserves. It's a blend of education and strategy for aspiring medical practitioners!
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State A Clear, Multi-Definition FRC
- Define FRC clearly using multiple equivalent definitions to impress examiners.
- State normal values (≈30 mL/kg) and the balance point between chest and lung recoil.
Use A Simple Structured Framework
- Use a structured framework (anaesthetic, surgical, patient) to explain FRC changes.
- Mention measurement methods briefly: helium dilution and body plethysmography and that spirometry can't measure RV.
Multiple Mechanisms Reduce FRC Under Anaesthesia
- Anaesthesia reduces FRC via multiple mechanisms: supine posture, loss of muscle tone, and 100% O2 causing loss of nitrogen splinting.
- PEEP can restore FRC but may reduce cardiac output by decreasing venous return.