Hemodynamics.kiran rai


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basis of hemodynamics

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  • Afterload is the pressure the ventricles must OVERCOME in order to pump the blood past the aorta.
  • Anacrotic rise is the initital upward slope of the waveform when the ventricle is contracting and forcing open the aortic valve.
  • Hemodynamics.kiran rai

    1. 2. Hemodynamics Physics of Blood flow in the circulation
    2. 3. Circulatory System <ul><li>Heart: </li></ul><ul><li>Has 2 collecting chambers - (Left, Right Atria) </li></ul><ul><li>Has 2 Pumping chambers - (Left, Right Ventricles) </li></ul>
    3. 5. Left Side of Heart Lungs Tissues Circulation Schematic Right Side of Heart A V V A Pulmonary Vein Pulmonary Artery Aorta Sup. & Inf. Vena Cava Pulmonary Valve Aortic Valve Tricuspid Valve Mitral Valve
    4. 6. Blood Vessels <ul><li>Arteries </li></ul><ul><li>Capillaries </li></ul><ul><li>Veins </li></ul><ul><li>Systemic Pathway: </li></ul><ul><li>Left Ventricle of Heart Aorta Arteries Arterioles </li></ul><ul><li>Capillaries </li></ul><ul><li>Venules Veins Right Atrium of the heart </li></ul>
    5. 7. Blood <ul><li>Composition: </li></ul><ul><ul><li>Approx 45% by Vol. Solid Components </li></ul></ul><ul><ul><ul><ul><ul><li>Red Blood Cells (12  m x 2  m) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>White Cells </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Platelets </li></ul></ul></ul></ul></ul><ul><ul><li>Approx 55% Liquid (plasma) </li></ul></ul><ul><ul><ul><ul><ul><li>91.5% of which is water </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>7% plasma proteins </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>1.5% other solutes </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li> </li></ul></ul></ul></ul></ul>
    6. 8. <ul><li>Viscosity of Blood = 3 3.5 times of water </li></ul>
    7. 9. Hemodynamic Principles <ul><li>CO = SV X HR </li></ul><ul><li>Stroke Volume : Amount of blood ejected by the left ventricle with each Cardiac Contraction. </li></ul><ul><li>Preload - Ventricular filling pressure at end diastole. </li></ul><ul><li>Afterload - Resistance the ventricle has to overcome to eject it’s content. </li></ul><ul><li>Contractility - Heart muscles pumping ability. </li></ul>
    8. 10. Cardiac Output <ul><li>Stroke volume X Heart rate. </li></ul><ul><li>Normal CO = 4-8 liters/min </li></ul><ul><li>CI=CO/BSA </li></ul><ul><li>Body surface area = Weight in Kg. x Height in cm. </li></ul><ul><li>Normal CI=2.8-4.2 L/min/m2 </li></ul><ul><li>A CI of 2.0 or less should be immediately reported to the physician!! </li></ul>
    9. 11. Four determinants of cardiac output Heart Rate x Stroke Volume Contractility Afterload Preload
    10. 13. Starling’s Law <ul><li>The strength of the contraction is proportionate to the stretch applied--- </li></ul><ul><li>Up to a point! </li></ul><ul><li>An overstretched heart cannot contract back well at all. </li></ul>
    11. 14. <ul><li>The stretching of muscle fibers in the ventricles </li></ul><ul><li>Results from blood volume in the ventricles at end-diastole </li></ul><ul><li>The greater the stretch during diastole, the more forcefully they contract during systole </li></ul>Preload Preload is the stretch of the balloon as air is blown into it. The more air, the greater the stretch.
    12. 15. Preload and Cardiac Output <ul><li>Preload will generally INCREASE CO </li></ul><ul><li>Myocardial fibers stretch and increase the force of contraction </li></ul><ul><li>Too much preload: heart becomes overstretched; results in diminished contraction and DECREASE CO </li></ul><ul><li>Decrease in preload, heart and vessels are underfilled, results in DECREASED CO </li></ul>
    13. 16. Preload <ul><li>Central Venous Pressure ( CVP) Measures the filling pressure of the Right Atrium at end diastole. </li></ul><ul><li>Normal CVP is 0-8 mmHg. </li></ul><ul><li>Pulmonary Artery (PCWP) reflects the filling pressure of the Left Ventricle at end diastole. </li></ul><ul><li>Normal PCWP is 6-12 mmHg. </li></ul><ul><li>The amount of blood in a ventricle before it contracts. </li></ul>
    14. 17. Increasing Preload: <ul><li>Crystalloids & colloids </li></ul><ul><li>Crystalloids: NS or LR </li></ul><ul><ul><li>Takes 1000 ml to increase blood volume by 200 ml </li></ul></ul><ul><li>Colloids used when acute vascular loss exists </li></ul>
    15. 18. Low CVP <ul><li>Decreased Venous return to the heart. </li></ul><ul><li>Hypovolemia. </li></ul><ul><li>Volume Loss </li></ul>
    16. 19. Elevated CVP <ul><li>Fluid Overload. </li></ul><ul><li>Heart Failure. </li></ul><ul><li>Cardiac Tamponade. </li></ul><ul><li>Tricuspid valve Regurgitation. </li></ul><ul><li>Increased Intrathoracic/Pulmonic pressures. </li></ul>
    17. 20. Left Heart Preload <ul><li>The amount of blood in the LV at the end of diastole </li></ul><ul><li>Measured by the pulmonary capillary wedge pressure (PCWP) </li></ul><ul><li>Normal PCWP 6-12mmHg </li></ul><ul><li>Obtained when PA balloon is inflated. </li></ul><ul><li>This blocks off all pressures from right side and all the PA catheter “see” is the filling pressure of Left side of heart. </li></ul>
    18. 21. <ul><li>The pressure that the ventricles must generate to overcome the higher pressure in the aorta to get the blood out of the heart </li></ul>Afterload Resistance is the knot on the end of the balloon, which the balloon has to work against to get the air out.
    19. 22. Factors Affecting Afterload <ul><li>Compliance of the aorta </li></ul><ul><li>Mass/viscosity of the blood: how thick or thin is it? </li></ul><ul><li>Vascular resistance: Are the blood vessels constricted or dilated? </li></ul><ul><li>Oxygen level: Hypoxemia will cause vasoconstriction. </li></ul><ul><li>The afterload force opposes muscle contraction” </li></ul><ul><li>Afterload is inversely proportional to stroke volume. </li></ul>
    20. 23. Afterload Reduction: <ul><li>Improves cardiac performance by reducing the resistance facing the ventricle during contraction. </li></ul><ul><li>Other factors, such as blood viscosity and valvular resistance, can influence afterload </li></ul><ul><li>Agents that reduce arterial resistance: </li></ul><ul><ul><li>Calcium channel blockers </li></ul></ul><ul><ul><li>ACE inhibitors </li></ul></ul><ul><ul><li>Arteriolar dilators </li></ul></ul><ul><ul><li>Beta blockers </li></ul></ul>
    21. 24. Afterload Increase and Increasing the BP: <ul><li>Increasing afterload with vasopressors is the most potent method. </li></ul><ul><li>Hypovolemia must be corrected before using vasopressors </li></ul><ul><li>Vasopressors increase myocardial oxygen consumption </li></ul><ul><li>May increase the BP but not the blood flow </li></ul><ul><li>Common agents: norepinephrine, dopamine, phenylephrine </li></ul>
    22. 25. IABP <ul><li>Decreases afterload </li></ul><ul><li>Improves coronary perfusion </li></ul>
    23. 27. <ul><li>The ability of the myocardium to contract normally </li></ul><ul><li>Influenced by preload </li></ul><ul><li>The greater the stretch, the more forceful the contraction </li></ul>Contractility The more air in the balloon, the greater the stretch, the farther the balloon will fly when air is released.
    24. 28. <ul><li>Determined by force and velocity of muscle contraction when loading conditions (preload and afterload) are held constant. </li></ul><ul><li>Can be influenced by neural, humoral or pharmacological factors. </li></ul>Contractility
    25. 29. Increased Contractility <ul><li>“ Fight or Flight” </li></ul><ul><ul><li>Sympathetic response </li></ul></ul><ul><ul><li>Catecholamine release </li></ul></ul><ul><li>Increased contractility also increased myocardial oxygen demand </li></ul>
    26. 30. Decreased contractility <ul><li>Decreased contractility </li></ul><ul><ul><li>Decreased stroke volume </li></ul></ul><ul><ul><li>Decreased myocardial oxygen demand </li></ul></ul><ul><li>Contractility decreases with: </li></ul><ul><ul><li>Hypoxia </li></ul></ul><ul><ul><li>Metabolic acidosis </li></ul></ul><ul><ul><li>Myocardial infarction </li></ul></ul><ul><ul><li>Hyperkalemia </li></ul></ul><ul><ul><li>Hypercapnia </li></ul></ul><ul><ul><li>Hypocalcemia </li></ul></ul>
    27. 31. Improving Contractility: <ul><li>Can occur through: </li></ul><ul><ul><li>Preload reduction </li></ul></ul><ul><ul><li>Afterload reduction </li></ul></ul><ul><ul><li>Direct contractile stimulation </li></ul></ul><ul><li>Contractile stimulating drugs in the ICU setting: </li></ul><ul><ul><li>Dobutamine </li></ul></ul><ul><ul><li>Dopamine </li></ul></ul><ul><ul><li>Amrinone </li></ul></ul>
    28. 32. Hemodynamic Monitoring <ul><li>Practical Applications </li></ul>
    29. 33. Examples of hemodynamic monitoring devices: <ul><li>Arterial Lines </li></ul><ul><li>RA/CVP </li></ul><ul><li>Pulmonary Artery Catheter </li></ul><ul><li>SvO2/CCO Catheter </li></ul><ul><li>Bedside BP cuff </li></ul>
    30. 34. Arterial Line Monitoring <ul><li>Arterial lines provide direct and continuous measurement of the patients systolic and diastolic BP via an electrical waveform and digital readout displayed on a monitor. </li></ul>
    31. 35. <ul><li>Anacrotic rise: Initial steep upward slope, Ventricular contraction, opening of aortic valve </li></ul><ul><li>Peak slope: continued stroke volume ejection from left ventricle </li></ul><ul><li>Down slope: peripheral runoff </li></ul><ul><li>Dicrotic notch: Aortic valve closes, diastole begins </li></ul>Arterial Line waveform
    32. 36. Leveling and Zeroing System
    33. 37. Central Venous Pressure/ RA Pressure Monitoring <ul><li>Tip of the catheter located in right atrium or superior vena cava </li></ul><ul><li>RA pressure (AKA CVP) measures venous return to the right heart </li></ul><ul><li>RA/CVP pressure is used to determine the “preload” or volume status of the right heart </li></ul>
    34. 38. RA/CVP Catheter Placement
    35. 39. RA/CVP Monitoring <ul><li>Normal RA/CVP is between 2-6 mm hg (read as a “mean” value) </li></ul><ul><li>Most critically ill patients require a RA pressure of 6-12 mm hg </li></ul><ul><li>RA pressures elevated > 15 - 20 mm hg caused by </li></ul><ul><ul><li>Fluid Overload </li></ul></ul><ul><ul><li>Pulmonary Problems </li></ul></ul><ul><ul><li>Right Heart failure </li></ul></ul><ul><li>Elevated RA pressures indicates hypervolemia; “Preload” in the right heart is too high </li></ul>
    36. 40. Use brown port for CVP monitoring. Arrow triple lumen CVC
    37. 41. PA Pressure & Waveform Analysis <ul><li>PA Pressure (PAP) – tip of the catheter is at the distal tip of the pulmonary artery (yellow port) with the balloon down </li></ul><ul><li>Normal PA Pressure is </li></ul><ul><li>20 - 30 mm hg (Systolic) </li></ul><ul><li>6 – 12 mm hg (Diastolic) </li></ul><ul><li>PA pressures: </li></ul><ul><ul><li>Document Q4 hours: wedge, CO, CI, SVR, PVR </li></ul></ul><ul><ul><li>PA waveform needs to be monitored for spontaneous wedging. </li></ul></ul>
    38. 42. Pulmonary Artery Catheter <ul><li>A 110 cm flow-directed, balloon tipped, multi-lumen catheter positioned in the distal branch of the pulmonary artery </li></ul><ul><ul><li>Yellow Port – PA distal lumen </li></ul></ul><ul><ul><li>Blue Port – Proximal (RA/CVP) lumen </li></ul></ul><ul><ul><li>White Port = Venous infusion lumen </li></ul></ul><ul><ul><li>Balloon Port – Inflate with NO more than 1.5 cc air to obtain INTERMITTENT PA wedge pressures </li></ul></ul><ul><ul><li>Thermistor Port – Core blood temperature </li></ul></ul><ul><ul><li>Thermal coil port - provides Continuos Cardia Output </li></ul></ul><ul><li>Used to obtain derived parameters of CI, Systemic (SVR) & Pulmonary Vascular Resistance (PVR); Sv02/CCO monitoring </li></ul>
    39. 43. PA Catheter Inflated for Wedge Pressure
    40. 44. PA Waveform Progression
    41. 45. PA Wedge Pressure <ul><li>PA wedge pressure – obtained by inflating distal balloon port w/ no more than 1.5 cc </li></ul><ul><li>Inflate the balloon slowly observe for a change in waveform from PA to “Wedge”. </li></ul><ul><li>Only use as much air as needed to obtain wedge. </li></ul><ul><li>Make a mental note of how much air is needed to wedge </li></ul><ul><li>Inflation will block off all pressures from right side of heart – it “sees” ahead to the left side of the heart </li></ul><ul><li>Do NOT inflate for longer than 15 seconds (prolonged inflation will result in pulmonary infarction, PA rupture & hemorrhage) </li></ul>
    42. 46. <ul><li>Hemodynamic data obtained by 2-D Doppler echo </li></ul><ul><li>Volumetric measurements </li></ul><ul><ul><li>SV and CO </li></ul></ul><ul><ul><li>Regurgitant volume and fraction </li></ul></ul><ul><ul><li>Qp/Qs </li></ul></ul><ul><li>Pressure gradients </li></ul><ul><ul><li>Maximal instantaneous gradient </li></ul></ul><ul><ul><li>Mean gradient </li></ul></ul>
    43. 47. <ul><li>Valve area </li></ul><ul><ul><li>Stenotic valve area </li></ul></ul><ul><ul><li>Regurgitant orifice area </li></ul></ul><ul><li>Intracardiac pressures </li></ul><ul><ul><li>PA pressures, LAP, LVEDP </li></ul></ul>
    44. 48. <ul><li>Volumetric Measurments </li></ul><ul><li>Stroke Volume and Cardiac Output </li></ul><ul><li>Flow velocity varies during ejection in a pulsatile system so flow velocity is summed as  VTI  or velocity-time integral </li></ul><ul><ul><ul><li>VTI = area enclosed by baseline and doppler spectrum </li></ul></ul></ul><ul><li>Flow = area x velocity </li></ul><ul><li>SV = CSA x VTI </li></ul><ul><li>CSA = π r2 </li></ul><ul><li>CSA = D2 x 0.785 </li></ul><ul><li>CO = SV x HR </li></ul>
    45. 49. What the hell are you talking about ?
    46. 51. <ul><li>1. PRELOAD- venous blood return to the heart </li></ul><ul><li>Controlled by; </li></ul><ul><li> Diuretics- </li></ul><ul><ul><li>lasix,bumex </li></ul></ul><ul><ul><li>Thiazides </li></ul></ul><ul><li> Ace inhibitors </li></ul><ul><li>♥ . Venous Dilation </li></ul><ul><li> Nitroglycerine </li></ul><ul><li> Ca+ channel blockers </li></ul><ul><li>clonidine (Catapress) </li></ul><ul><li>methyldopa </li></ul><ul><li>trimethaphan (arfonad) </li></ul><ul><li>↓ Dobutamine </li></ul><ul><li> Morphine </li></ul>2. CONTRACTILITY - forcefulness of contractility  Ca+ channel blockers  Digoxin  Dopamine/Dobutamine  Milrinone/amrinone 3. AFTERLOAD – work required to open aortic valve and eject blood – resistance to flow in arteries °  Dopamine (at higher doses)  Ace inhibitors  Nipride/lesser extent Nitro  Calcium channel blockers  Labetalol Drugs of Hemodynamics <ul><li>4. HEART RATE – </li></ul><ul><li> Beta blockers </li></ul><ul><li> Calcium channel blockers </li></ul><ul><li> Atropine </li></ul><ul><li> Dopamine </li></ul><ul><li> Dobutamine </li></ul>
    47. 52. Q & A...... Whew....Glad thats over !!!!