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Transpulmonary Thermodilution Technology TPTD. Theory and Practice. Haemodynamic Monitoring with TPTD. Principles of function Thermodilution Contractility parameters Extravascular lung water Pulmonary permeability. Central venous catheter • jugular • subclavian.
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Transpulmonary Thermodilution Technology TPTD Theory and Practice
Haemodynamic Monitoring with TPTD • Principles of function • Thermodilution • Contractility parameters • Extravascular lung water • Pulmonary permeability
Central venous catheter • jugular • subclavian Thermodilution arterial catheter • femoral
EVLW RA RV PBV LA LV EVLW Principles of Measurement After central venous injection the cold bolus sequentially passes through the various intrathoracic compartments Bolus injection concentration changes over time (Thermodilution curve) Lungs Right heart Left heart The temperature change over time is registered by a sensor at the tip of the arterial catheter
EVLW RA RV PBV LA LV EVLW Intrathoracic Compartments (mixing chambers) Intrathoracic Thermal Volume (ITTV) Pulmonary Thermal Volume (PTV) Largest single mixing chamber Total of mixing chambers
Haemodynamic Monitoring • Principles of function • Thermodilution • Contractility parameters • Extravascular Lung Water • Pulmonary Permeability
Calculation of the Cardiac Output The CO is calculated by analysis of the thermodilution curve using the modified Stewart-Hamilton algorithm Tb Injection t k x Vi x (Tb - Ti) COTD a = AUC Tb = Blood temperature Ti = Injectate temperature Vi = Injectate volume AUC = Area under the thermodilution curve K = Correction constant, made up of specific weight and specific heat of blood and injectate
Thermodilution curves The area under the thermodilution curve is inversely proportional to the CO. Temperature 36,5 Normal CO: 5.5l/min 37 Temperature Time 36,5 low CO: 1.9l/min 37 Temperature Time 36,5 High CO: 19l/min 37 10 5 Time
Transpulmonary vs. Pulmonary Artery Thermodilution Transpulmonary TD (EV 1000) Pulmonary Artery TD (PAC) Aorta PA Pulmonary Circulation Lungs LA central venous bolus injection RA LV RV arterial thermo-dilution catheter Right Heart Left heart Body Circulation In both procedures only part of the injected indicator passes the thermistor. Nonetheless the determination of CO is correct, as it is not the amount of the detected indicator but the difference in temperature over time that is relevant!
Validation of the Transpulmonary Thermodilution n (Pts / Measurements) r Comparison with Pulmonary Artery Thermodilution bias ±SD(l/min) Friedman Z et al., Eur J Anaest, 2002 17/102 -0,04 ± 0,41 0,95 Della Rocca G et al., Eur J Anaest 14, 2002 60/180 0,13 ± 0,52 0,93 Holm C et al., Burns 27, 2001 23/218 0,32 ± 0,29 0.98 Bindels AJGH et al., Crit Care 4, 2000 45/283 0,49 ± 0,45 0,95 Sakka SG et al., Intensive Care Med 25, 1999 37/449 0,68 ± 0,62 0,97 Gödje O et al., Chest 113 (4), 1998 30/150 0,16 ± 0,31 0,96 McLuckie A. et a., Acta Paediatr 85, 1996 9/27 0,19 ± 0,21 - / - Comparison with the Fick Method Pauli C. et al., Intensive Care Med 28, 2002 18/54 0,03 ± 0,17 0,98 Tibby S. et al., Intensive Care Med 23, 1997 24/120 0,03 ± 0,24 0,99
Extended analysis of the thermodilution curve From the characteristics of the thermodilution curve it is possible to determine certain time parameters Tb Injection Recirculation In Tb e-1 MTt DSt t MTt: Mean Transit time the mean time required for the indicator to reach the detection point DSt: Down Slope time the exponential downslope time of the thermodilution curve Tb = blood temperature; lnTb = logarithmic blood temperature; t = time
Calculation of ITTV and PTV By using the time parameters from the thermodilution curve and the CO ITTV and PTV can be calculated Tb Injection Recirculation In Tb e-1 MTt DSt t Pulmonary Thermal Volume PTV = Dst x CO Intrathoracic Thermal Volume ITTV = MTt x CO
EVLW RA RV PBV LA LV EVLW Calculation of ITTV and PTV Intrathoracic Thermal Volume (ITTV) Pulmonary Thermal Volume (PTV) PTV = Dst x CO ITTV = MTt x CO
EVLW RA RV PBV LA LV EVLW Volumetric preload parameters – GEDV Global End-diastolic Volume (GEDV) ITTV PTV GEDV GEDV is the difference between intrathoracic and pulmonary thermal volumes
The new Volume View method to assess GEDV S2 S1 GEDV = CO x MTt x f (S2/S1)
EVLW RA RV PBV LA LV EVLW Volumetric preload parameters – ITBV Intrathoracic Blood Volume (ITBV) GEDV PBV ITBV ITBV is the total of the Global End-Diastolic Volume and the blood volume in the pulmonary vessels (PBV)
Introduction to the PiCCO-Technology Summary and Key Points - Thermodilution • TPTD Technology is a less invasive method for monitoring the volume status and cardiovascular function. • Transpulmonary thermodilution allows calculation of various volumetric parameters. • The CO is calculated from the shape of the thermodilution curve. • The volumetric parameters of cardiac preload can be calculated through advanced analysis of the thermodilution curve. • For the thermodilution measurement only a fraction of the total injected indicator needs to pass the detection site, as it is only the change in temperature over time that is relevant.
Haemodynamic Monitoring • Principles of function • Thermodilution • Contractility parameters • Extravascular Lung Water • Pulmonary Permeability
Contractility Contractility is a measure for the performance of the heart muscle • Contractility parameters of TPTD technique: • dPmx (maximum rate of the increase in pressure) • GEF (Global Ejection Fraction) • CFI (Cardiac Function Index) kg
Contractility parameter from the pulse contour analysis dPmx = maximum velocity of pressure increase The contractility parameter dPmx represents the maximum velocity of left ventricular pressure increase.
Contractility parameter from the pulse contour analysis dPmx = maximum velocity of pressure increase n = 220 y = -120 + (0,8* x) r = 0,82 p < 0,001 femoral dP/max [mmHg/s] 2000 1500 1000 500 0 0 500 1000 1500 2000 LV dP/dtmax [mmHg/s] de Hert et al., JCardioThor&VascAnes 2006 dPmx was shown to correlate well with direct measurement of velocity of left ventricular pressure increase in 70 cardiac surgery patients
SV SV SV = LVEF = GEF RVEF = LVEDV GEDV / 4 RVEDV Global Ejection Fraction (GEF) (transpulmonary thermodilution) Assessment of cardiac function by EJECTION FRACTION RV ejection fraction (RVEF) (pulmonary artery thermodilution) LV ejection fraction (LVEF) (echocardiography)
Contractility parameters from the thermodilution measurement GEF = Global Ejection Fraction LA 4 x SV GEF = GEDV RA LV RV • is calculated as 4 times the stroke volume divided by the global end-diastolic volume • reflects both left and right ventricular contractility
Contractility parameters from the thermodilution measurement GEF = Global Ejection Fraction sensitivity 1 15 18 8 12 16 10 0,8 19 5 0,6 20 D FAC, % -20 -10 10 20 0,4 22 -5 0,2 -10 r=076, p<0,0001 n=47 0 0,2 0,4 0,6 0,8 0 -15 1 specifity D GEF, % Combes et al, Intensive Care Med 30, 2004 Comparison of the GEF with the gold standard TEE measured contractility in patients without right heart failure
Contractility parameters from the thermodilution measurement CFI = Cardiac Function Index CI CFI = GEDVI • is the CI divided by global end-diastolic volume index • is - similar to the GEF – a parameter of both left and right ventricular contractility
Hypotension AP ↓ Low cardiac output CO ↓ Depressed contractility Inadequate preload Vasoplegia Acute circulatory failure Low GEDV Low GEF/CFI Low SVR What do we need for management of acute circulatory failure ?
Haemodynamic Monitoring • Principles of function • Thermodilution • Contractility parameters • Extravascular Lung Water • Pulmonary Permeability
EVLW What for ? diagnostic prognostic therapeutic
Calculation of Extravascular Lung Water (EVLW) ITTV – ITBV = EVLW The Extravascular Lung Water is the difference between the intrathoracic thermal volume and the intrathoracic blood volume. It represents the amount of water in the lungs outside the blood vessels.
Animal validation against gravimetry Katzenelson et al. Crit Care Med 2004 (Dog) Mondejar et al. J Crit Care 2003 (Pig) Kirov et al. Crit Care 2005 (Sheep)
Validation of Extravascular Lung Water EVLW from the TPTD technique has been shown to have a good correlation with the measurement of extravascular lung water via the gravimetry and dye dilution reference methods Dye dilution ELWI ELWIST (ml/kg) Y = 1.03x + 2.49 40 25 20 30 n = 209 r = 0.96 15 20 10 10 5 R = 0,97 P < 0,001 0 0 0 10 20 30 0 5 10 15 20 25 ELWI by gravimetry ELWITD (ml/kg) Sakka et al, Intensive Care Med 26: 180-187, 2000 Katzenelson et al,Crit Care Med 32 (7), 2004
EVLW as a quantifier of lung edema High extravascular lung water is not reliably identified by blood gas analysis ELWI (ml/kg) 30 20 10 0 0 50 150 250 350 450 550 PaO2 /FiO2 Boeck J, J Surg Res 1990; 254-265
EVLW as a quantifier of lung oedema Chest x ray – does not reliably quantify pulmonary oedema and is difficult to judge, particularly in critically ill patients Dradiographic score 80 r = 0.1 p > 0.05 60 40 20 0 -15 -10 10 15 -20 DELWI -40 -60 -80 Halperin et al, 1985, Chest 88: 649
EVLW as a quantifier of lung oedema Extravascular lung water index (ELWI) normal range:3 – 7 ml/kg Normal range Pulmonary oedema ELWI = 7 ml/kg ELWI = 19 ml/kg ELWI = 14 ml/kg ELWI = 8 ml/kg
Mortality (%) 100 n = 81 90 *p = 0.002 n = 373 80 80 70 60 70 50 60 40 50 30 40 20 30 10 0 20 0 0 4 - 6 6 - 8 8 - 10 10 - 12 12 - 16 16 - 20 > 20 ELWI (ml/kg) Relevance of EVLW Assessment The amount of extravascular lung water is a predictor for mortality in the intensive care patient Mortality(%) < 7 n = 45 7 - 14 n = 174 14 - 21 n = 100 > 21 n = 54 ELWI (ml/kg) Sturm J in: Lewis, Pfeiffer (eds): Practical Applications of Fiberoptics in Critical Care Monitoring, Springer Verlag Berlin - Heidelberg - NewYork 1990, pp 129-139 Sakka et al , Chest 2002
Relevance of EVLW Assessment Volume management guided by EVLW can significantly reduce time on ventilation and ICU length of stay in critically ill patients, when compared to PCWP oriented therapy, Ventilation Days Intensive Care days * p ≤ 0,05 n = 101 * p ≤ 0,05 22 days 9 days 15 days 7 days EVLW Group PAC Group EVLW Group PAC Group Mitchell et al, Am Rev Resp Dis 145: 990-998, 1992
Haemodynamic Monitoring • Principles of function • Thermodilution • Contractility parameters • Extravascular Lung Water • Pulmonary Permeability
Differentiating Lung Oedema PVPI = Pulmonary Vascular Permeability Index EVLW EVLW PVPI = PBV PBV • is the ratio of Extravascular Lung Water to Pulmonary Blood Volume • is a measure of the permeability of the lung vessels and as such can classify the type of lung oedema (hydrostatic vs. permeability caused)
Pulmonary Vascular Permeability Index = PVPI >>>> EVLW PVPI = EVLW/PBV PVPI = EVLW/PBV PBV Hydrostatic pulmonary edema Permeability pulmonary edema
Classification of Lung Oedema with the PVPI Difference between the PVPI with hydrostatic and permeability lung oedema: Lung oedema hydrostatic permeability PBV PBV EVLW EVLW EVLW EVLW PBV PBV PVPI normal (1-3) PVPI raised (>3)
Validation of the PVPI PVPI can differentiate between a pneumonia caused and a cardiac failure caused lung oedema. PVPI 4 3 2 Pneumonia Cardiac insufficiency 16 patients with congestive heart failure and acquired pneumonia. In both groups EVLW was 16 ml/kg. Benedikz et al ESICM 2003, Abstract 60
Clinical Relevance of the Pulmonary Vascular Permeability Index EVLWIanswers the question: How much water is in the lungs? PVPIanswers the question: Why is it there? and can therefore give valuable aid for therapy guidance!