1. Haemodynamic Monitoring
Theory and Practice

2. Haemodynamic Monitoring
Physiological Background
Monitoring
Optimising the Cardiac Output
Measuring Preload
Introduction to PiCCO Technology
Practical Approach
Fields of Application
Limitations

3. Volume Responsiveness
Measuring Preload
Volumetric Preload Parameters, Volume Responsiveness and Filling Pressures
Preload
Volumetric
Preload parameters
GEDV / ITBV
Volume Responsiveness
SVV / PPV
Filling Pressures
CVP / PCWP
What parameters are available for measuring the preload?
- classical parameters: cardiac filling pressures CVP (via CVC) and PCWP (via pulmonary arterial catheter)
- static volumetric preload parameters: GEDV (global end-diastolic volume and ITBV (intrathoracic blood volume)
- dynamic parameters SVV (stroke volume variation) and PPV (pulse pressure variation). In the narrower sense, these are not preload parameters but parameters of the heart‘s preload responsiveness (reaction of cardiac stroke volume to volume administration) 3

4. Correlation between Central Venous Pressure CVP and Stroke Volume
Measuring Preload
Role of the filling pressures CVP / PCWP
Correlation between Central Venous Pressure CVP and Stroke Volume
The relevance of the filling pressures for assessing cardiac preload has long been disputed and has been refuted in numerous publications.
Neither the absolute level of the CVP (shown on left) nor the changes in CVP (shown on right) correlate with stroke volume.
CVP therefore not suitable for assessing volume status.
Kumar et al., Crit Care Med 2004;32: 4

5. Measuring Preload
Role of the filling pressures CVP / PCWP
Correlation between Pulmonary Capillary Wedge Pressure PCWP and Stroke Volume
The pulmonary capillary wedge pressure (PCWP) and alterations of this do not show any correlation with cardiac ejection either.
Thus measurement of cardiac preload is not possible by means of the traditionally employed PCWP either.
Kumar et al., Crit Care Med 2004;32: 5

6. Measuring Preload
Role of the filling pressures CVP / PCWP
The filling pressures CVP and PCWP do not give an adequate assessment of cardiac preload.
The PCWP is, in this regard, not superior to CVP (ARDS Network, N Engl J Med 2006;354: ).
Pressure is not volume!
FACCT study by the ARDS Networks, published in the New England Journal of Medicine: no difference in the outcome of ARDS patients with CVP-guided fluid management and those with volume therapy guided by the PCWP.
Better: measure volumes directly instead of estimating them from the pressure measurement.
The level of the filling pressures is subject to many influencing factors so a valid statement about volume status is not possible.
Only exception: low filling pressures indicate hypovolaemia
Influencing Factors:
Ventricular compliance
Position of catheter (PAC)
Mechanical ventilation
Intra-abdominal hypertension 6

7. Volume Responsiveness Volumetric Preload parameters
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
Preload
Volume Responsiveness
SVV / PPV
Filling Pressures
CVP / PCWP
Volumetric Preload parameters
GEDV / ITBV
Introduction to the volumetric preload parameters.
These allow direct measurement of the cardiac filling volume so that this does not have to be estimated through a pressure measurement. 7

8. GEDV = Global Enddiastolic Volume
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
GEDV = Global Enddiastolic Volume
Lungs
Pulmonary Circulation
The global end-diastolic volume consists of the end-diastolic volumes of all four cardiac chambers. Even if this volume does not exist physiologically (diastole of all four cardiac chambers is not simultaneous), it does reflect the filling status of the heart and is a valid parameter of cardiac preload compared to the filling pressures.
Left heart
Right Heart
Body Circulation
Total volume of blood in all 4 heart chambers 8

9. GEDV shows good correlation with the stroke volume
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
GEDV shows good correlation with the stroke volume
The correlation of the global end-diastolic volume with the cardiac stroke volume is considerably better than with CVP or PCWP.
GEDV is thus much better suited for measuring the cardiac preload.
Michard et al., Chest 2003;124(5): 9

10. ITBV = Intrathoracic Blood Volume
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
ITBV = Intrathoracic Blood Volume
Lungs
Pulmonary Circulation
Left heart
The intrathoracic blood volume corresponds to the global end-diastolic blood volume plus the blood in the pulmonary circulation.
Right heart
Body Circulation
ITBV =GEDV + PBV
Total volume of blood in all 4 heart chambers plus the pulmonary blood volume 10

11. ITBV is normally 1.25 times the GEDV
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
ITBV is normally 1.25 times the GEDV
ITBVTD (ml)
1000
2000
3000
The intrathoracic blood volume is usually 25% higher than the global end-diastolic blood volume. A linear association has been demonstrated for the two parameters.
The ITBV can therefore be calculated from the GEDV.
ITBV = 1.25 * GEDV – 28.4 [ml]
GEDV (ml)
GEDV vs. ITBV in 57 Intensive Care Patients
Sakka et al, Intensive Care Med 2000; 26: 11

12. The static volumetric preload parameters GEDV and ITBV
Measuring Preload
Role of the volumetric preload parameters GEDV / ITBV
The static volumetric preload parameters GEDV and ITBV
Are superior to filling pressures for assessing cardiac preload
(German Sepsis Guidelines)
Are, in contrast to cardiac filling pressures, not falsified by other pressure influences (ventilation, intra-abdominal pressure)
The German Sepsis Society confirms in its official guidelines that volumetric parameters are superior to the classical filling pressures for assessing cardiac preload.
GEDV and ITBV are not falsified by extravascular pressure influences, in contrast to CVP and PCWP. 12

13. Volumetric Preload parameters Volume Responsiveness
Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
Preload
Filling Pressures
CVP / PCWP
Volumetric Preload parameters
GEDV / ITBV
Volume Responsiveness
SVV / PPV
The parameters stroke volume variation (SVV) and pulse pressure variation (PPV) are not preload parameters in the narrower sense but parameters of the heart‘s preload responsiveness. They thus provide information on whether the heart will respond to volume administration with an increase in cardiac stroke volume. They can help to determine whether volume administration is useful to increase cardiac output. 13

14. Fluctuations in blood pressure during the respiration cycle
Measuring Preload
Physiology of the dynamic parameters of volume responsiveness
Fluctuations in blood pressure during the respiration cycle
Early Inspiration
Late Inspiration
Intrathoracic pressure
„Squeezing “ of the pulmonary blood
Left ventricular preload
Left ventricular stoke volume
Systolic arterial blood pressure
Intrathoracic pressure
Venous return to left and right ventricle
Left ventricular preload
Left ventricular stroke volume
Systolic arterial blood pressure
Inspiration
Expiration
Inspiration
Expiration
Everyone knows the “fluctuation“ of the arterial pressure curve in hypovolaemic patients, that is, the fluctuation in pulse pressure amplitude with the respiratory cycle.
This is due to ventilation-induced preload changes, which are more marked, the more hypovolaemic the patient is.
PPmax
PPmin
PPmax
PPmin 14
Reuter et al., Anästhesist 2003;52:

15. Fluctuations in stroke volume throughout the respiratory cycle
Measuring Preload
Physiology of the dynamic parameters of volume responsiveness
Fluctuations in stroke volume throughout the respiratory cycle SV SV SV
Preload
An identical preload change (x-axis) leads to different changes in the stroke volume (y-axis) depending on the area of the Frank-Starling curve in which the heart is working.
The more hypovolaemic the patient, the greater the stroke volume variation and pulse pressure variation.
The SVV and PPV can be measured correctly only if the induced preload changes are always the same and no other fluctuations in the stroke volume occur. For correct measurement of SVV and PPV the patient‘s ventilation must be completely controlled (no spontaneous breathing) and there has to be a regular sinus rhythm. V V
Mechanical Ventilation
Intrathoracic pressure fluctuations
Changes in intrathoracic blood volume
Preload changes
Fluctuations in stroke volume 15

16. SVV = Stroke Volume Variation
Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
SVV = Stroke Volume Variation
SVmax
SVmin
SVmean
mean
The variation in stroke volume over the respiratory cycle
Correlates directly with the response of the cardiac ejection to preload increase (volume responsiveness) 16

17. SVV is more accurate for predicting volume responsiveness than CVP
Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
SVV is more accurate for predicting volume responsiveness than CVP
Sensitivity 1
0,8
0,6
0,4
The illustration shows that the SVV has considerably greater sensitivity and specificity for assessing volume responsiveness than CVP. According to the graph, the probability of predicting volume responsiveness correctly with the CVP is 50%, thus equivalent to tossing a coin.
- - - CVP
___ SVV
0,2
0,5
Specificity 1
Berkenstadt et al, Anesth Analg 92: , 2001 17

18. PPV = Pulse Pressure Variation
Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
PPV = Pulse Pressure Variation
PPmean
PPmax
PPmin
The variation in pulse pressure amplitude over the respiration cycle
Correlates equally well as SVV for volume responsiveness 18

19. Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
A PPV threshold of 13% differentiates between responders and non-responders to volume administration
respiratory
changes in arterial
pulse pressure (%)
Non – Responders
n = 24
This study showed how the PPV can distinguish the reaction of cardiac ejection to volume administration (preload increase). A value of 13% differentiates between responders (PPV>13%) and non-responders (PPV<13%) to volume administration.
Responders
n = 16
Michard et al, Am J Respir Crit Care Med 162, 2000 19

20. The dynamic volume responsiveness parameters SVV and PPV
Measuring Preload
Role of the dynamic volume responsiveness parameters SVV / PPV
The dynamic volume responsiveness parameters SVV and PPV
are good predictors of a potential increase in CO due to volume administration
are only valid with patients who are fully ventilated and who have no cardiac arrhythmias
Despite the limitations, PPV and SVV are valuable parameters for optimising the patient‘s volume status. 20

21. EVLW = Extravascular Lung Water
Role of extravascular lung water EVLW
EVLW = Extravascular Lung Water
Lungs
Pulmonary circulation
Left Heart
Brief presentation of another parameter that is not a preload parameter but is nevertheless highly important for guiding volume management:
Extravascular lung water signifies the water content of the lungs outside the blood vessels. The EVLW therefore consists of the interstitial, intracellular and intraalveolar water of lung tissue.
Right Heart
Body circulation
Extravascular water content of the lung 21

22. The Extravascular Lung Water EVLW
Role of extravascular lung water EVLW
The Extravascular Lung Water EVLW
is useful for differentiating and quantifying lung oedema
is, for this purpose, the only parameter available at the bedside
functions as a warning parameter for fluid overload
Pulmonary oedema can be diagnosed with certainty and its severity determined with the extravascular lung water. The parameter can be measured at the bedside using thermodilution, in contrast to conventional methods such as chest X-ray.
The level of lung water and changes in this can provide important information for guiding volume therapy, as the point of time from which volume therapy leads to the development of pulmonary oedema can be identified. 22

23. Measuring Preload
Summary and Key Points
The volumetric parameters GEDV / ITBV are superior to the filling pressures CVP / PCWP for measuring cardiac preload.
The dynamic parameters of volume responsiveness (SVV and PPV) can predict whether CO will respond to volume administration.
GEDV and ITBV show what the actual volume status is, whilst SVV and PPV reflect the volume responsiveness of the heart.
For optimal control of volume therapy simultaneous monitoring of both the static preload parameters and the dynamic parameters of volume responsiveness is sensible (F. Michard, Intensive Care Med 2003;29: 1396). 23