Hemodynamics - Putting the puzzle together

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    10-Feb-2015

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Haemodynamic data can be acquired in many ways. However we obtain the raw data we still have a big problemWhat do all these figures mean? How can we put it all together to help our patients?Associate Professor Brendan E. Smith.School of Biomedical Science, Charles Sturt University,Specialist in Anaesthesia and Intensive Care, Bathurst Base Hospital, Bathurst, NSW, Australia

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1. Haemodynamics- putting the puzzle together. HR SVR Hb SV DO2 CVP CO SpO2 BP Associate Professor Brendan E. Smith. School of Biomedical Science, Charles Sturt University, Specialist in Anaesthesia and Intensive Care, Bathurst Base Hospital, Bathurst, NSW, Australia. 2. Data Acquisition.Haemodynamic data can be acquired in many ways Trans-Thoracic Echocardiography Trans-Oesphageal Echocardiography USCOM Doppler examination Impedence Plethysmography Pulmonary Artery Catheter PiCCO Etc etc. Each has its own benefits and drawbacks, BUT. 3. However we obtain the raw data we still have a big problem What do all these figures mean?How can we put it all together to help our patients? 4. Oxygen Delivery DO2 X Blood Pressure X Hb SpO2 Cardiac Output SVRStroke Volume Heart Rate Preload Inotropy Afterload 5. To live we have to have Blood pressure and blood flow! 6. Blood PressureBlood pressuredoesnt tell usanything aboutthe hearts abilityto deliveroxygen! 7. Her blood pressure is normal.Anybody NOT want to know her C.O. and DO2?!! (By permission of Dr Joe Brierley, GOSH, London.) 8. Haemodynamics used to bea highly invasive science 9. Insertion of PA Catheter wasDifficult (especially in children)DangerousTime consumingExpensiveOf doubtful value! 10. All the data provided by PAC(and more) can be obtained non-invasively 11. Oxygen Delivery DO2 Blood PressureHb SpO2 Cardiac Output SVRStroke Volume Heart Rate Preload Inotropy Afterload 12. The Ultrasonic Cardiac Output Monitor - USCOM 13. Suprasternal CW Doppler Parasternal CW Doppler 14. What other data do we get? Vpk = Peak Ejection Velocity 15. CO / CI = Cardiac Output / Index 16. Why Cardiac Index v Cardiac Output? 17. The same applies to Stroke Volume, SVR and many other parameters in haemodynamics so we use Stroke Volume Index - SVI SVR index SVRI DO2 Index DO2I VO2 Index VO2I Etc 18. MD = Minute Distance = Aortic Velocity 19. SV = Stroke volumeEjection Time + SV = Inotropy 20. SVR = Systemic Vascular Resistance 21. Oxygen Delivery DO2 Blood Pressure Hb SpO2 Cardiac Output SVRStroke Volume Heart Rate Preload Inotropy Afterload 22. Pulse Oximeters 23. Pulse Oximetry + Hb 24. Central Venous Oxygen Saturation 25. Oxygen Delivery DO2 Blood Pressure Hb SpO2 Cardiac Output SVRStroke Volume Heart Rate Preload Inotropy Afterload 26. AfterloadDepends on:Degree of vasoconstriction / dilationDensity & viscosity of bloodFlow rate of blood / surface tension forcesElasticity of arteriesStroke volume 27. These are all the same factorsthat determine mean aortic rootpressureSo afterload is exactly the same as meanaortic root pressure.MAP = diastolic + (systolic diastolic)But can we use radial artery pressure? 28. Integrated PressureP2 PP1 t t P2 Mean Pressure = P1 P.dt = Pressure time integral = Pti time 29. Pti-A Pti-R 30. Pti-Aortic and Pti-Radial are close enough in clinical practice to make no significantdifference to haemodynamic calculations. (error typically 95% of cases this is done by clinical judgment alone! Which inotrope and how much? What are our therapeutic targets? How do we know weve reached them? If only we could measure inotropy!! 37. How Can We Measure Inotropy? 38. Conservation of EnergyThe energy produced by cardiac contraction must be converted to either Potential Energy (PE) in the form of blood pressure or Kinetic Energy (KE) in the form of blood flow. But can we measure PE & KE? Is the measurement reliable? How long does it take? Can we monitor Rx with it? 39. Potential EnergyPE developed by the heart appears in the form of the energy needed to raise the stroke volume up to arterial pressure in a given systolic time, the Flow Time. Work Done = P x V PE = MAP x SV Flow Time P = Mean Arterial Pressure - CVP SV and Flow Time are measured directly using CW Doppler. 40. Potential Energy PE = BPm x SV x 10-3 7.5 x FT 7.5 and 10-3 are required to convert BP in mmHg to kPa and SV in ml to m3 to conform with SI units.The unit for PE is therefore Joules/second, or Watts. 41. Kinetic Energy The KE of any moving mass is given by KE = mV2 The mass of blood ejected per Stroke Volume is - SV(ml) x 10-6 x Density of blood, (1,055 kg/m3)The KE developed by the heart in a given flow time is KE = 1 x SV x 10-6 x x V2 2 x Flow Time (V is measured directly by CW Doppler) 42. Total Inotropy = PE + KE ( = blood pressure + blood flow)Inotropy = BPm x SV x 10-3 + 1 x SV x 10-6 x x V2 7.5 x FT 2 x FT (The Smith-Madigan Formula)The SI unit of inotropy is therefore the Watt. 43. Inotropy IndexBut how do we judge inotropy in patients of varying size, e.g. large and small adults, children, infants? By analogy to cardiac index which is Cardiac Index = Cardiac Output Body Surface Area Smith-Madigan Inotropy Index = Inotropy BSA The SI unit of SMII is therefore W/m2 44. Smith-Madigan Inotropy Index Normal Controls 1.6 2.2 W/m2 Left Ventricular Failure 0.4 1.1 W/m2 Septicaemic Shock 0.6 1.2 W/m2 45. Cardiogenic Shock74 year old man with STEMIBP 84/44, pulse 114, SpO2 84% on 10L/min O2Pulmonary Oedema +++No urine outputPaO2 64mmHg, PaCO2 28mmHgLactate 8.4 46. >2.4 60-75 8 12 14 Dobutamine mcg/kg/min0.62 0.97 1.13 1.38 SMII W/m2