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Advance in Hemodynamic Monitoring

Advance in Hemodynamic Monitoring. By Dr H P Shum. Outline. Introductions What we have previously – A line / CVC/ PAC Advance techniques for haemodynamic monitoring. Introductions.

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Advance in Hemodynamic Monitoring

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  1. Advance in Hemodynamic Monitoring By Dr H P Shum

  2. Outline • Introductions • What we have previously – A line / CVC/ PAC • Advance techniques for haemodynamic monitoring

  3. Introductions • Hemodynamics is concerned with the forces generated by the heart and the resulting motion of blood through the cardiovascular system • Hemodynamic monitoring is the intermittent or continuous observation of physiological parameters pertaining to the circulatory system with a view to early detection of need for therapeutic interventions

  4. 4 factors that affecting the haemodynamic conditions Myocardial contraction and heart rate Vasoactivity Intravascular volume

  5. Old equipments • Arterial line • Real time SBP, DBP, MAP • Pulse pressure variation (PP) • ΔPP (%) = 100 × (PPmax - PPmin)/([PPmax + PPmin]/2) • >= 13% (in septic pts,) discriminate between fluid responder and non respondaer(sensitivity 94%, specificity 96%) • Am J Respir Crit Care Med 2000, 162:134-138

  6. Arterial line • Advantages • Easy setup • Real time BP monitoring • Beat to beat waveform display • Allow regular sampling of blood for lab tests • Disadvantages • Invasive • Risk of haematoma, distal ischemia, pseudoaneurysm formation and infection

  7. Old equipments • Central venous catheter • Measurement of CVP, medications infusion and modified form allow for dialysis

  8. Limitation of CVP Obstruction of the great veins Mechanical ventilation Decrease right ventricular compliance Tricuspid regurgitation Systemic venoconstriction

  9. Central venous catheter • Advantages • Easy setup • Good for medications infusion • Disadvantages • Cannot reflect actual RAP in most situations • Multiple complications • Infections, thrombosis, complications on insertion, vascular erosion and electrical shock

  10. Old equipment • Pulmonary arterial catheter

  11. Indications for PAP monitoring • Shock of all types • Assessment of cardiovascular function and response to therapy • Assessment of pulmonary status • Assessment of fluid requirement • Perioperative monitoring

  12. Clinical applications of PAC PAC can generate large numbers of haemodynamic variables • Central venous pressure (CVP) • Pulmonary arterial occlusion pressure (PAOP) • Cardiac output / cardiac index (CO / CI) • Stroke volume (SV) • R ventricle ejection fraction/ end diatolic volume (RVEF / RVEDV) • Systemic vascular resistance index (SVRI) • Pulmonary vascular resistance index (PVRI) • Oxygen delivery / uptake (DO2 / VO2) =LAP = LVEDP  By thermodilution

  13. Area under curve is inversely proportion to rate of blood flow in PA ( = CO)

  14. Patient with hypotension • Vasogenic • Low CVP • High CI • Low SVRI •  Consider vasopressor • Cardiogenic • High CVP • Low CI • High SVRI •  Consider inotopic / IABP • Hypovolemia • Low CVP • Low CI • High SVRI •  Consider fluid challenge

  15. Mixed Venous Saturation SvO2 • Measured in pulmonary artery blood • Marker of the balance between whole body O2 delivery (DO2) and O2 consumption (VO2) • VO2 = DO2 * (SaO2 – SvO2) • In fact, DO2 determinate by CO, Hb and SaO2. Therefore, SvO2 affected by • CO • Hb • Arterial oxygen saturation • Tissue oxygen consumption

  16. Mixed Venous Saturation SvO2 • Normal SvO2 70-75% • Increased SvO2 • Increased delivery • high CO • hyperbaric O2 • Low consumption • sedation • paralysis • cyanide toxicity • Decreased SvO2 • increased consumption • pain, hyperthermia • decreased delivery • low CO • anemia • hypoxia

  17. PAC • Advantages • Provide lot of important haemodynamic parameters • Sampling site for SvO2 • Disadvantages • Costly • Invasive • Multiple complications (eg arrhythmia, catheter looping, balloon rupture, PA injury, pulmonary infarction etc) • Mortality not reduced and can be even higher Crit Care Med 2003;31: 2734-2741 JAMA 1996;276 889-897

  18. Advance in haemodynamic assessment • Modification of old equipment • Echocardiogram and esophageal doppler • Pulse contour analysis and transpulmonary thermodilution • Partialcarbondioxiderebreathing with application of Fick principle • Electricalbioimpedance

  19. truCCOMS system

  20. As CO increase, blood flow over the heat transfer device increase and the device require more power to keep the temp. difference Therefore, provide continuous CO data

  21. Objective  To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two " gold standard " methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution.Design  Prospective clinical trial.Setting  Cardiac surgery operating room and surgical ICU in a university hospital.Material and methods  In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently.Results  In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r2 = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement –0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r2 = 0.56, the bias was –0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were –1.39 to +1.25 l/min.Conclusion  The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.

  22. TruCCOMS system • Advantage • Continuous CO monitoring • Provision of important haemodynamic parameter as PAC • Disadvantage • Invasive • Costly • Complications associated with PAC use

  23. Transthoracic echo • Assessment of cardiac structure, ejection fraction and cardiac output • Based on 2D and doppler flow technique

  24. Echo doppler ultrasound • Measure blood flow velocity in heart and great vessels • Based on Doppler effect  “ Sound freq. increases as a sound source moves toward the observer and decreases as the soure moves away”

  25. For transthoracic echo • Haemodynamic assessment for SV and CO • Flow rate = CSA x flow velocity • Because flow velocity varies during ejection, individual velocities of the doppler spectrum need to be summed • Sum of velocities called velocity time integral (VTI) • SV = CSA x VTI • CSA =( LVOT Diameter /2 )2 *  • Therefore SV = D2 * 0.785 * VTI • CO = SV * HR

  26. Transthoracic echo • Advantages • Fast to perform • Non invasive • Can assess valvular structure and myocardial function • No added equipment needed • Disadvantages • Difficult to get good view (esp whose on ventilator / obese) • Cannot provide continuous monitoring

  27. Transesophageal echo • CO assessment by Simpson or doppler flow technique as mentioned before • Better view and more accurate than TTE • Timeconsumingandrequireahighlevelofoperatorskillsandknowledge

  28. Esophageal aortic doppler US • Doppler assessment of decending aortic flow • CO determinate by measuring aortic blood flow and aortic CSA • Assumingaconstantpartitionbetweencaudalandcephalicbloodsupplyareas • CSA obtain eitherfromnomogramsorbyM-mode US • Probe is smaller than that for TEE • Correlate well with CO measured by thermodilution Crit Care Med 1998 Dec;26(12):2066-72 Decending aorta

  29. Normovolemia

  30. Esophageal aortic doppler US • Advantages • Easy placement, minimal training needed (~ 12 cases) • provide continuous,real-time monitoring • Low incidence of iatrogenic complications • Minimal infective risk • Disadvantages • High cost • Poor tolerance at awake patient, so for those intubated • Probedisplacement can occur during prolonged monitoring and patient’s turning • High interobserver variability when measuring changes in SV in response to fluid challenges

  31. Pulse contour analysis • Arterial pressure waveform determinate by interaction of stroke volume and SVR

  32. Pulse contour analysis • Because vascular impedance varies between patients, it had to be measured using another modality to initially calibrate the PCA system • The calibration method usually employed was arterial thermodilution or dye dilution technique • PCA involves the use of an arterially placed catheter with a pressure transducer, which can measure pressure tracings on a beat-to-beat basis • PiCCO and LiDCO are the two commonly used model

  33. T injection t P t What is the PiCCO-Technology? • The PiCCO-Technology is a unique combination of 2 techniques • for advanced hemodynamic and volumetric management without • the necessity of a right heart catheter in most patients: Transpulmonary Thermodilution CV Bolus injection CALIBRATION PULSIOCATH Pulse Contour Analysis

  34. Parameters measured with the PiCCO-Technology The PiCCO measures the following parameters: • Thermodilution Parameters • Cardiac Output CO • Global End-Diastolic Volume GEDV • Intrathoracic Blood Volume ITBV • Extravascular Lung Water EVLW* • Pulmonary Vascular Permeability Index PVPI* • Cardiac Function Index CFI • Global Ejection Fraction GEF • Pulse Contour Parameters • Pulse Contour Cardiac Output PCCO • Arterial Blood Pressure AP • Heart Rate HR • Stroke Volume SV • Stroke Volume Variation SVV • Pulse Pressure Variation PPV • Systemic Vascular Resistance SVR • Index of Left Ventricular Contractility dPmx*

  35. 3How does the PiCCO-Technology work? • Most of hemodynamic unstable and/or severely hypoxemic patients are • instrumented with: Central venous line (e.g. for vasoactive agents administration…) Arterial line (accurate monitoring of arterial pressure, blood samples…) • The PiCCO-Technology uses any standard CV-line and a thermistor- • tipped arterial PiCCO-catheter instead of the standard arterial line.

  36. PiCCO Catheter CV • Central venous line(CV) • PULSIOCATH thermodilution catheter with lumen for arterial pressure measurement • Axillary: 4F (1,4mm) 8cm • Brachial: 4F (1,4mm) 22cm • Femoral: 3-5F (0,9-1,7mm) 7-20cm • Radial: 4F (1,4mm) 50cm A B R F No Right Heart Catheter !

  37. Right Heart Left Heart EVLW* RV PBV LV RA LA EVLW* A. Thermodilution parameters PiCCO Catheter e.g. in femoral artery Bolus Injection • Transpulmonary thermodilution • measurement only requires • central venous injection of a cold • (< 8°C) or room-tempered • (< 24°C) saline bolus… Lungs

  38. Transpulmonary thermodilution: Cardiac Output • After central venous injection of the indicator, the thermistor at the tip of the arterialcatheter measures the downstream temperature changes. • Cardiac output is calculated by analysis of the thermodilution curve using a modifiedStewart-Hamilton algorithm: injection CO Calculation:  Area under the Thermodilution Curve Tb t Tb = Blood temperature Ti = Injectate temperature Vi = Injectate volume ∫ ∆ Tb .dt = Area under the thermodilution curve K = Correction constant, made up of specific weight and specific heat of blood and injectate

  39. Transpulmonary thermodilution: Volumetric parameters 1 • All volumetric parameters are obtained by advanced analysis of the thermodilution curve: For the calculations of volumes… Advanced Thermodilution Curve Analysis Tb Mtt: Mean Transit time time when half of the indicator has passed the point of detection in the artery injection recirculation ln Tb …and… -1 e DSt: Down Slope time exponential downslope time of the thermodilution curve t DSt MTt …are important.

  40. LAEDV Transpulmonary thermodilution: Volumetric parameters 2 After injection, the indicator passes the following intrathoracic compartments: ITTV PTV Thermodilution curve measured with arterial catheter CV Bolus Injection RVEDV LVEDV RAEDV Lungs Left Heart Right Heart • The intrathoracic compartments can be considered as a series of “mixing chambers” for the distribution of the injected indicator (intrathoracic thermal volume). • The largest mixing chamber in this series are the lungs, here the indicator (cold) has its largest distribution volume (largest thermal volume).

  41. PBV LVEDV RAEDV RVEDV LAEDV EVLW* EVLW* Calculation of volumes ITTV = CO * MTtTDa LAEDV RAEDV RVEDV LVEDV PTV PTV = CO * DStTDa PTV GEDV= ITTV - PTV LAEDV RAEDV RVEDV LVEDV ITBV= 1.25 * GEDV EVLW* = ITTV - ITBV

  42. Pulmonary Vascular Permeability Index • Pulmonary Vascular Permeability Index (PVPI*) is the ratio of Extravascular • Lung Water (EVLW*) to pulmonary blood volume (PBV). It allows to identify the • type of pulmonary oedema. normal EVLW* EVLW* PBV Normal Lung PVPI* =  PBV normal Extra Vascular Lung Water Pulmonarv Blood Volume normal elevated EVLW* EVLW* Hydrostatic pulmonary edema PBV PVPI *=  PBV normal elevated elevated Permeability pulmonary edema EVLW* EVLW* PVPI* =  PBV PBV elevated normal

  43. SV SV RVEF = LVEF = RVEDV LVEDV Global Ejection Fraction • Ejection Fraction: Stroke Volume related to End-Diastolic Volume Lungs Left Heart Right Heart EVLW* PBV RAEDV RVEDV EVLW* LAEDV LVEDV Stroke Volume SV 3 2 1 &  4 x SV GEF = GEDV Global Ejection Fraction (GEF) (transpulmonary thermodilution) RV ejection fraction (RVEF) (pulmonary artery thermodilution) LV ejection fraction (LVEF) (echocardiography)

  44.  P(t) dP PCCO = cal • HR • ( + C(p) • ) dt SVR dt Systole Pulse Contour Analysis - Principle P [mm Hg] t [s] Shape of pressure curve Heart rate Aortic compliance Patient-specific calibration factor (determined by thermodilution) Area under pressure curve

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