Count to 10 - Anaesthetic Primary Podcast EP24 – Control of Cardiac Output & Pressure | Anaesthetic Primary Topic | Cardiac Physiology | CT10
Jul 31, 2024
Dive into the dynamics of cardiac physiology as critical concepts like preload, afterload, and contractility are unraveled. Discover the Frank-Starling mechanism and how it influences stroke volume. Explore the Guyton Curves and the Left Ventricular Pressure-Volume Loop for a clearer understanding of cardiac output. Additionally, get insights on past assessment questions to prepare effectively for exams. This episode is packed with diagrams and essential study tips that will elevate your knowledge in anaesthetics.
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Estimate Preload With Surrogates And Trends
- Use end-diastolic volume or pressure as surrogates to estimate LV preload clinically.
- Track trends in CVP rather than single values to judge underfilling or overfilling.
Afterload Is Ventricular Wall Stress
- Afterload equals ventricular wall stress which follows Laplace's law: pressure × radius ÷ (2 × wall thickness).
- Increasing wall thickness reduces wall stress, explaining LV hypertrophy in aortic stenosis.
Positive Pressure Ventilation Lowers LV Afterload
- Remember positive pressure ventilation raises external thoracic pressure and can reduce LV afterload.
- Consider this unloading effect when managing patients on mechanical ventilation.