GasGasGas - The FRCA Primary Exam Podcast VivaCast 13 - Ultrasound - Cardiac Output Monitoring - Diathermy
Mar 19, 2025
Dive into the fascinating world of ultrasound in anaesthesia, from vascular access to echocardiography. Explore the physics behind ultrasound machines and the significance of the Doppler effect in measuring blood flow. Discover both non-invasive and invasive techniques for assessing cardiac output, including the roles of pulmonary artery catheters. Gain insights into the intricacies of diathermy, its safety concerns, and strategies to minimize ECG interference. Perfect for those preparing for the FRCA exams!
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How Ultrasound Forms Images
- Ultrasound builds images by emitting high-frequency sound and timing echoes to map depth.
- It assumes straight-line travel, uniform speed and attenuation, which causes artefacts when violated.
Doppler Depends On Angle To Flow
- The Doppler effect shifts ultrasound frequency when echoes return from moving blood cells.
- Angle to flow matters and is ideally kept under about 60 degrees for accurate velocity detection.
Grade Cardiac Output Monitoring By Invasiveness
- Assess cardiac output progressively: start with clinical exam, then non-invasive monitors, then invasive techniques.
- Use more invasive methods only when clinically necessary because they are closer to the heart and more accurate but riskier.