PiCCO Operators Manual Ver 4.1x May 2002

PULSION Medical Systems

8

PiCCO

SYSTEM DESCRIPTION

8-1

8.1 GENERAL INFORMATION ... 8-4 8.1.1 INTENDED USE 8-4 8.1.2 INDICATIONS 8-4 8.1.3 CONTRAINDICATIONS 8-4 8.1.4 WARNINGS 8-4 8.1.5 CAUTIONS 8-5 8.2 UNPACKING AND INSPECTION ... 8-7 8.2.1 UNPACKING 8-7 8.2.2 INSPECTION 8-7 8.3 STARTING UP ...8-7 8.4 MENU DESCRIPTION ... 8-10 8.4.1 MAIN MENU 8-10 8.4.2 INPUT MENU 8-11 8.4.3 CONFIGURATION MENU 8-12 8.4.4 THERMODILUTION DISPLAY PAGE 8-12 8.4.5 PULSE CONTOUR DISPLAY PAGE / 8-15 8.4.6 PRESSURE ZEROING MENU 8-17 8.5 PRINTER... 8-18 8.6 CONTRAST CONTROL

... 8-18

8.7 PULSE INDICATOR, WARNING INDICATOR

/

... 8-19

8.8 STANDBY MODE... 8-19 8.9 ERROR MESSAGES ... 8-20 8.10 CLEANING AND DISINFECTING THE EQUIPMENT ... 8-22 8.11 MAINTENANCE/SERVICE ... 8-22 8.12 TRANSMISSION OF AP SIGNAL TO BEDSIDE MONITOR ... 8-24 8.13 DATA TRANSMISSION WITH RS232 INTERFACE ... 8-25 8.13.1 GENERAL 8-25 8.13.2 DATA TRANSMISSION 8-26 9

DISPOSABLES

9-1

9.1 PULSIOCATH PCCO CATHETER KITS ... 9-1 9.2 PCCO MONITORING KITS ... 9-2 9.3 INJECTATE TEMPERATURE SENSOR HOUSING ... 9-2 10 ACCESSORIES

10-1

11 SPECIFICATIONS

11-1

ii

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APPENDIX A

PiCCO

A-1

B

EQUATIONS FOR CALCULATED VALUES ... A-1 A.1 THERMODILUTION DISPLAY PAGE A-1 A.2 PULSE CONTOUR DISPLAY PAGE A-2 INTERNATIONAL SYMBOLS ... B-1

C

WARRANTY... C-1

D

GLOSSARY... D-1

E

CERTIFICATES ...E-E

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FIGURES Fig. 1: Schematic description of an indicator dilution curve and the time characteristics of interest...4-1 Fig. 2: Schematic description of the indicator mixing chambers of the cardiopulmonary systems... 4-2 Fig. 3:

Regression analysis between global end -diastolic volume index (GEDVI) and intrathoracic blood

Fig. 4:

Regression analysis between the stroke volume index (SVI) and the global end-diastolic volume

volume index (ITBVI) in intensive care patients ... 4-3

index (GEDVI) in pigs... 4-4 Fig. 5:

Regression analysis between stroke volume index (SVI) and central venous pressure (CVP) in pigs4-5

Fig. 6:

Regression analysis between stroke volume index (SVI) and pulmonary capillary wedge pressure (PCWP) in pigs... 4-5

Fig. 7:

Patient management by combined use of EVLW and ITBV... 4-8

Fig. 8:

Schematic relationship between global end-diastolic volume index (GEDVI) and cardiac index (CI). 4-9

Fig. 9:

Characteristic compliance during the heart phases ... 5-1

Fig. 10: Determination of the individual aortic compliance ... 5-2 Fig. 11: Calculation of pulse contour cardiac output (PCCO). ... 5-2 Fig. 12: Front panel of the PiCCO ... 8-1 Fig. 13: Rear panel of the PiCCO... 8-2 Fig. 14: AUX Adapter. ... 8-3 Fig. 15: Printer... 8-18

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PREFACE Carefully read this Operator’s Manual before attempting to use the PiCCO!

WARNINGS Warnings are information you should know to avoid injuring patients and personnel.

CAUTIONS Cautions are information you should know to avoid damaging equipment and software.

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1 QUICK REFERENCE GUIDE PiCCO - QUICK REFERENCE GUIDE PURPOSE 1.

2.

Transpulmonary thermodilution: Cardiac output (CO), cardiac function index (CFI), as well as the estimation of intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). Continuous monitoring after initial cali bration of arterial pulse contour with transpulmonary thermodilution: Pulse contour cardiac output (PCCO), heart rate (HR), stroke volume (SV), SV variation (SVV), arterial pressure (AP), systemic vascular resistance (SVR), and index of cardiac contractility (dPmx ).

THERMODILUTION MEASUREMENT 1. Change to the “Thermodilution display page” 2. Press “Start measurement-key”

3. Wait until the blood temperature status “STABLE“ is displayed

4. Inject the bolus as fast and steady as possible (< 5 sec !)

PULSE CONTOUR MONITORING 1. Change to the “Pulse contour display page”

STARTING UP

2. Change between pulse contour display page and trend display page, if required

Knowledge of the accompanying o perator’s manual is absolutely vital!

3. Change between indexed or absolute values, if required

1. If the PV4045 Injectate temperature sensor housing is used, cool (<8°C) injectate (e.g. saline solution 0.9%)! If the PV4046 Injectate temperature sensor hou sing is used together with roomtempered injectate (<24°C), prepare appropriate more injectate volume! 2. Insert a central venous catheter (CVC)

3. Insert a PULSIOCATH thermodilution catheter (e.g. PV2014L08, PV2014L16, PV2011) into a larger artery (e.g. femoral or axillary artery) 4. Connect the potential equalization stud of the PiCCO to a secondary ground source separate from the primary grounding source 5. Connect the hospital grade mains power cable 6. Connect PV4045 / PV4046 to the distal lumen of the CVC 7. Connect the “Injectate temperature se nsor cable“ to the PiCCO and to the “Injectate temperature sensor housing” 8. Connect the prepared PULSION monitoring kit (e.g. PV8015) to the PULSIOCATH thermodilution catheter

9. Connect the “arterial pressure/ temper ature cable“ to the PiCCO, the thermodilution catheter, and the monitoring kit 10. Switch on the PiCCO

11. Enter all patient specific and measur ement relevant parameters to the Input menu 12. Perform a “zero adjustment” of the pressure signal Related patents: EP0637932, US5526817 EP0666056, US5769082 Further patents pending

SYMBOLS Input menu Configuration menu

Thermodilution display page Delete measurement

Start measurement key Indexed values (based on body surface area or body weigth) Absolute values Trend display page Pulse contour display page Pressure zeroing menu Zero key Decrease values Increase values

Previous position Next position Exit key

MEASURED AND CALCULATED VARIABLES Thermodilution determinations: CO Cardiac output1) CFI Cardiac function index GEDV Global end-diastolic volume ITBV Intrathoracic blood volume1) EVLW Extravascular Lung Water 1) Pulse contour analysis: PCCO Pulse contour cardiac output1) HR Heart rate SV Stroke volume1) SVV Stroke volume variation

APsys APdia MAP dPmx SVR

Systolic arterial pressure Diastolic arterial pressure Mean arterial pressure Max. pressure increase velocity Systemic vascular resistance1)

1) Parameters can also be displayed as indexed values

RANGES OF NORMAL VALUES Values gained through clinical experience, i.e. without guarantee

CI CFI

Normal ranges

Unit

3.5 - 5.0

l/min/m2

4.5 - 6.6

1/min

ITBI

850 - 1000

ml/m2

ELWI

3.0 – 7.0

ml/kg

SVI

40 - 60

ml/m2

APsys

90 -130

mmHg

60 - 90

HR

APdia

60 - 90

MAP

70 – 90

dP mx SVRI

1200 – 2000 1200 - 2000

1/min

mmHg mmHg

mmHg/s

dyn·s·cm -5·m 2

ERROR MESSAGES /CODES *** +++ ----

Not plausible / not available Value is above specification range Value is below specification range

See operator’s manual for detailed explanation of displayed error messages (chapter 7.9) (ST= STATUS) ST

Interpretation

1 Error in determin ation of Ti 2 - 6 Error in calculation of thermodilution curve parameters 7 Thermodilution curve longer than 90 sec 8

9 10

Blood temperature lower than injectate temperature Invalid calibration Inline sensor error

WARNING For safety of operation and for accuracy of measurements, only disposables and accessories approved by PULSION Medical Systems may be used with the PiCCO.

Stahlgruberring 28 •• D-81829 München Tel. +49-(0)1805 PULSION •• +49-(0)89-459914-0 •• Fax +49-(0)89-459914-18 E-mail: [email protected] •• Internet: www.pulsion.de

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2 GENERAL INFORMATION 2.1 INTENDED USE The PULSION PiCCO is intended for determination and monitoring of cardiopulmonary and circulatory variables. Cardiac output is determined both continuously through arterial pulse contour analysis and intermittently through transpulmonary thermodilution technique. In addition, the PiCCO measures heart rate, systolic and diastolic and derives mean arterial pressure. Analysis of the thermodilution curve in terms of mean transit time (MTt) and downslope time (DSt) is used for determination of intra- and extra- vascular fluid volumes. If patient’s weight and height are entered the PiCCO presents the derived parameters indexed to body surface area (BSA) respectively body weight (BW).

2.2 INDICATION The PULSION PiCCO is indicated in patients where cardiovascular and circulatory vo lume status monitoring is necessary. Such as patients in surgical, medical, cardiac and burn specialty units as well as other specialty units where cardiovascular monitoring is desired and patients undergoing surgical interventions of such magnitude that cardiovascular monitoring is necessary.

2.3 CONTRAINDICATIONS Due to the invasiveness of the measurement, it should not be applied in patients where the placement of indwelling arterial catheter is contraindicated. The PiCCO should only be applied in patients where the expected results are reasonable in comparison to the risks. Patients receiving intra-aortic balloon counter pulsation (IABP) cannot be monitored with the pulse contour analysis of the device.

2.4 WARNINGS Federal law restricts this device to sale by or on the order of a physician. This device is intended for use in health care facilities by trained health care professionals. This device provides monitoring of physiological parameters. The clinical significance of changes in monitored parameters should be determined by a physician. For safety of operation and for accuracy of measurements, only disposables and accessories approved by PULSION Medical Systems may be used with the PiCCO. Explosion hazard when used in the presence of flammable anesthetics. Failure on the part of the responsible individual hospital or institution employing the use of the PiCCO to follow the service instruction may cause undue equipment failure and possible health hazards.

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WARNINGS CONTINUED

When placing the arterial catheter in a large artery (i.e. femoral, brachial or axillary arteries) do not advance the tip of the catheter into the aorta. An intracardiac blood pressure measurement is not allowed. This means that the measuring position (catheter tip) should not be directly in the heart. When high frequency devices for surgery are used, the standard for high frequency devices for surgery IEC/TR3 61289-1 has to be followed. The patient is protected against electrical burns by enhanced isolations between patient and the PiCCO and by placement of the pressure transducer away from the body. Discard all disposables after use. Reuse (e.g.: after re -sterilization) of disposables may cause infections in the patient. Do not reconnect to electrical power if liquid has entered the PiCCO. Short circuit may damage the device and cause hazardous conditions for patient and user. Removal of potential equalization stud from the rear of the PiCCO voids the IEC approval. Do not use a 3 wire to 2 wire adapter for the PiCCO. Do not touch the patient, bed or device during defibrillation. Do not allow conductive parts of the disposables to be in contact with any conducting parts of the device.

2.5 CAUTIONS Inspect the PiCCO thoroughly for damage. If the PiCCO seems to be damaged, contact PULSION Medical Systems. Do not use the PiCCO if the device appears to be damaged. Product damage may occur unless proper care is exercised during the unpacking and installation. The user must verify the safety and proper state of the device before it is used. If the system check detects a failure, no function will be available and “SERVICE” is dis played on the screen. Turn the PiCCO off and contact your local PULSION representative for service. If your representative is not available, please direcltly contact PULSION Medical Systems (telephone number listed in chapter 8.11). Do not attempt to use or repair the PiCCO. If zero adjustment is not performed, the blood pressure values can be wrong. Zero adjustment of the pressure transducer is mandatory.

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In the PCCO calibration restore menu an old calibration factor may be used. Using an old calibration factor can lead to erroneous results. Make sure that the old calibration factor is still valid, before using this option.

CAUTIONS CONTINUED When the PiCCO is connected to a bedside monitor, perform zero calibration of the PiCCO first and then the bedside monitor. After every change of AP Correction, a recalibration of the pulse contour analysis by performing a thermodilution measurement is necessary. If the pulse contour parameters are not plausible, they should be checked by a thermodilution measurement. The continuous pulse contour cardiac output measurement will be recalibrated automat ically. Faulty measurements can be caused by incorrectly placed catheters, defective connections or sensors and by electromagnetic interference (e.g.: electric blankets, electric coagulation). Displayed ITBV can be erroneously high wi th aortic aneurysm in combination with thermodilution measurement in the femoral artery. Remember to take the PiCCO OFF STANDBY when patient monitoring continues. Ancillary equipment that may be connected to the analog or digital interface has to meet the corresponding IEC specifications (e.g.: IEC 950 for data processing devices and IEC 601 for electromedical devices). Furthermore, all configurations have to meet the system standard IEC 601-1-1. Everyone who connects additional devices to the signal inp ut or signal output of the PiCCO is changing the system configuration and is responsible for the adherence of the standard IEC 6011-1. All units of the device are protected against malfunction that may be caused by defibrillators. Apart from intermittent measurement errors, defibrillation has no effect on the safety or function of the device. Do not expose the PiCCO to temperatures above 40 ºC (104 ºF) or below 10 ºC (38 ºF) accuracy of the measured values may be affected. Do not place other equipment and containers with liquid on top of the PiCCO

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3 INTRODUCTION Only measurement of clinically relevant hemodynamic parameters results in correct diagnosis and appropriate therapy in critically ill patients. Today, intravascular pressure and cardiac output (C.O.) monitoring are frequently pe rformed in the operating room and intensive care unit. Currently, C.O. is mostly measured intermittently although continuous measurement would be preferable. Continuous measurement of cardiac output appears to be a significant improvement in hemodynamic monitoring of critically ill patients. The method for continuous cardiac output should be as safe as possible, easy to use and it should be applicable without any restrictions. A majority of current techniques for measuring continuous cardiac output are complex, cumbersome and expensive. The most common technique for measuring continuous C.O. is thermodilution utilizing a heating pulmonary artery catheter (PAC). Compared to this method, estimation of C.O. from the arterial pulse contour is less invasive and produces a real "beat to beat" signal. Additionally, pulse contour cardiac output (PCCO) is easily applicable in critically ill patients. The arterial pulse contour method for measuring cardiac output was originally described by Otto Frank in 1899. Since then, a variety of pressure contour equations for estimating beat to beat stroke volume have been developed. The PiCCO is a device for continuous cardiac output measurement combined with cardiac preload volume and lung water monitoring without the need for a pulmonary artery catheter. The PULSION PiCCO computes the C.O. utilizing an improved arterial pulse contour analysis algorithm. Pulse contour cardiac output (PCCO) is calibrated by means of a transpulmonary thermodilution measurement. A bolus of cold normal saline or 5% dextrose in water is injected through any central venous catheter. A thermodilution curve is recorded by an arterial thermodilution catheter that also serves as pressure monitoring access. In addition to calibration of the PCCO, transpulmonary thermodilution also yields cardiac preload volume and an estimate of both, intrathoracic blood volume (ITBV) and extravascular lung water (EVLW).

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Following parameters can be derived by transpulmonary thermodilution: Absolute parameters

Indexed parameters

Parameter Cardiac output, transpulmonary

Abbr. C.O.a

Unit l/min

Abbr. CIa

Unit l/min/m2

Cardiac function index

CFI

1/min ml

ITBVI

ml/m 2

Extravascular lung water

EVLW

ml

EVLWI ml/kg

Intrathoracic blood volume

ITBV

After initial calibration the following parameters can continuously be derived by pulse contour analysis: Absolute parameters Indexed parameters Parameter

Abbr.

Unit

Abbr.

Unit

Pulse contour cardiac output

PCCO

l/min

PCCI

l/min/m2

Systolic arterial blood pressure

APsys

mm Hg

Mean arterial blood pressure

MAP

mm Hg

Stroke volume

SV

ml

SVI

ml/m 2

Systemic vascular resistance

SVR

dyn•s•cm-5

SVRI

dyn•s•cm-5•m2

Index of left ventricular contractility

dP/dtmax mmHg/s

Diastolic arterial blood pressure Heart rate Stroke volume variation

3-2

APdia HR SVV

mm Hg 1/min %

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4 INTERMITTENT VOLUMETRIC THERMODILUTION 4.1 PRINCIPLES OF CARDIAC OUTPUT DETERMINATION Cardiac output (C.O.) is generally determined using the Stewart-Hamilton method. To accomplish thermodilution determination, a known volume of cold (at least 10°C lower than blood temperature) solution is injected intravenously as fast as possible. The recorded downstream temperature change is dependent on the flow and on the volume through which the cold indicator has passed. As a result, a thermodilution curve can be constructed. The PiCCO detects the cold indicator in the arterial system (preferably in the femoral artery). Cardiac output (C.O.) by thermodilution is calculated as follows:

CO = [(Tb – Ti) • Vi • K] / [∫∆Tb • dt] T b: T i: Vi:

∫∆Tb • dt: K:

(1)

Blood temperature before the injection of cold bolus Temperature of the injection solution (injectate) Injection volume Area under the thermodilution curve Correction constants, made up of specific weights and specific heat of blood and injectate

4.2 PRINCIPLES OF VOLUME CALCULATION Specific volumes can be calculated by multiplying cardiac output with characteristic time variables of the thermodilution curve. The PULSION PiCCO dete rmines the mean transit time (MTt) of the thermodilution curve as well as the expone ntial downslope time (DSt).

At = appearance time MTt = mean transit time DSt = exponential downslope time Fig. 1:

Schematic description of an indicator dilution curve and the time characteristics of interest

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MTt volume The product of C.O. and MTt represent the volume transversed by the relevant indicator, i.e. total volume between the sites of injection and detection. This volume is often referred to as "needle to needle volume". DSt volume The product of C.O. and DSt represent the largest individual mixing volume in a series of indicator dilution mixing chambers.

CV bolus injection

RAEDV

RVEDV

Arterial TD catheter

EVLW

LAEDV

PBV

LVEDV

EVLW RAEDV: Right atrial end-diastolic volume RVEDV: Right ventricular end-diastolic volume PBV: Pulmonary blood volume Fig. 2:

LAEDV: Left atrial end-diastolic volume LVEDV: Left ventricular end-diastolic volume EVLW: Extravascular lung water

Schematic description of the indicator mixing chambers of the cardiopulmonary systems

4.3 PARAMETERS OBTAINED BY TRANSPULMONARY THERMODILUTION The following paramters are derived by the PiCCO from a central venous injection and transpulmonary detection with a thermodilution catheter. [1, 2] The application of a pulmonary artery catheter is not necessary. Parameter Cardiac output, transpulmonary Cardiac function index Intrathoracic blood volume Extravascular lung water

Absolute parameters Abbr. Unit C.O. l/min CFI 1/min ITBV ml EVLW

ml

Indexed parameters Abbr. Unit CIa l/min/m2 ITBVI

EVLWI

ml/m 2 ml/kg

4.3.1 CARDIAC OUTPUT TRANSPULMONARY (C.O.) Transpulmonary thermodilution cardiac output (C.O.) serves as the basic parameter for calculation of various blood volumes. The trasnpulmonary thermodilution curves are four to five times longer than those of the pulmonary artery. Compared to pulmonary artery the rmodilution, the transpulmonary thermodilution measurement has minimal ventilatory variations. As a result, C.O. provides a representative mean value over the ventilatory cycle. [6, 8, 9, 11, 14, 15] 4-2

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4.3.2 INTRATHORACIC BLOOD VOLUME (ITBV) Cardiopulmonary or, more precisely, intrathoracic blood volume measurement has been performed with indicator dilution techniques for over thirty years. ITBV estimation using single thermodilution method The PiCCO offers the possibility to assess ITBV derived from global end-diastolic volume (GEDV) determined by thermodilution measurement. GEDV correlates well with ITBV in both experimental and in clinical studies, as shown in figure 3. Using regression analysis of GEDV (determined by thermodilution) and ITBV (determined by thermal-dye-dilution) a regression equation can be derived. Using this equation, ITBV (obtained without dye dilution) can be estimated [3, 4, 5]:

ITBV = 1.25 • GEDV

Fig. 3:

(2)

Regression analysis between global end-diastolic volume index (GEDVI) and intrathoracic blood volume index (ITBVI) in intensive care patients

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Global end-diastolic volume (GEDV) Global end -diastolic volume is the sum of all end-diastolic volumes of the atria and the ventricles. Thus, GEDV is equivalent to preload volume of the total heart. GEDV can be determined through thermodilution at bedside.

GEDV = C.O.a • (MTtTDa – DStTDa)

(3)

MTt TDa: mean transit time of the cold indicator from the site of injection to the site of dete ction DSt TDa: exponential downslope time of the arterial thermodilution curve

(Patho-) physiological significance of GEDV Following diagram demonstrates the Frank -Starling relationship between GEDVI and stroke volume index (SVI). The circulating blood volume of ten pigs was either suddenly decreased or increased. The relationship SVI/GEDVI for the volumes tested is linear in contrast to the well known curvilinear SVI/end-diastolic pressure relationship. The regression line for the SVI/GEDVI relationship does not intercept the Y-axis at zero. The Y-axis intercept at SVI = 0 is equivalent to the baseline preload volume of the heart that does not take part in the Frank-Starling mechanism (this dead space volume is often referred to as unstressed volume).

Fig. 4:

4-4

Regression analysis between the stroke volume index (SVI) and the global end-diastolic volume index (GEDVI)

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PiCCO

Commonly, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) are used as indicators of cardiac preload. However, both CVP and PAOP are dependent on intravascular filling, intrathoracic pressure, vascular compliance and cardiac contractility. In contrast to pressures, GEDV represents cardiac preload volume. Following diagrams show the behavior of central venous pressure (CVP, figure 5) and pulmonary capillary wedge pressure (PCWP, figure 6) in the experiments mentioned above. The result lead to the conclusion that CVP and PCWP are poor indicators for cardiac preload compared with GEDV.

Fig. 5:

Regression analysis between stroke volume index (SVI) and central venous pressure (CVP)

Fig. 6:

Regression analysis between stroke volume index (SVI) and pulmonary capillary wedge pressure (PCWP)

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(Patho-) physiological significance of ITBV Intrathoracic blood volume (ITBV) consists of the global end -diastolic volume (GEDV, approximately 4/5 of ITBV) and the pulmonary blood volume (PBV). Three volumes are found in the thorax, the intrathoracic blood volume, the intrathoracic gas volume and the extravascular lung water. Due to the limited expansion ability of the thorax, the volumes interact and change proportionally to each other. A potential fourth compartment is space occupying tumors or pleural effusions that change the overall volume of the chest cavity. ITBV as a guide in hemodynamic management In numerous experimental studies, ITBV was shown to be a sensitive indicator of cardiac preload compared to central venous pressure or pulmonary artery occlusion pressure. In addition, in direct comparison with right ventricular end -diastolic volume, ITBV proves to be a sensitive indicator of cardiac preload. [16, 19, 22] Lichtwarck-Aschoff et al. [17] were able to show that in intensive care patients on mechanical ventilation, ITBV reflects the status of the circulating blood volume. In contrast, the clinical standard used to date "cardiac filling pressures" (central venous pressure and pulmo nary artery occlusion pressure) showed no relation to vascular volume status. [20, 21] 4.3.3 EXTRAVASCULAR LUNG WATER (EVLW) Extravascular lung water correlates to extravascular thermal volume in the lungs and is evaluated through the mean transit time method [30]:

EVLW = ITTV – ITBV

(4)

EVLW estimation (EVLW*) through estimated ITBV (ITBV*) Arterial thermodilution results in pulmonary thermal volume (PTV) and intrathoracic thermal volume (ITTV) as direct measurement values, as well as the diffe rence between the two volumes, i.e. the global end-diastolic volume (GEDV). Therefore, extravascular lung water (EVLW) is assessable:

EVLW* = ITTV – ITBV* = ITTV – 1.25 • GEDV

(5)

(Patho-) Physiological significance of EVLW The water content in the lungs increases through left heart failure, pneumonia, sepsis, intoxication, burns etc. EVLW can be increased by increased fluid transport to the interstitium, resulting from either increased intravascular filtration pressure (left heart failure, volume overload) or an increased pulmonary vascular permeability for plasma proteins, which pull a water wrapping along with them, corresponding to their colloidosmotic pressure (endotoxic shock, pneumonia, sepsis, intoxication, burns). EVLW is the only determinable bedside parameter with which the lung status, respectively the pulmonary permeability damages can be quantified, especially when pulmonary edema has been caused by increased pulmonary vascular permeability. 4-6

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Blood gases and the lung function indices resulting from these are not organ specific, as they are not only dependent on the lung status, but also on the lung perfusion and ventilation. Correlation coefficients between EVLW and oxygenation indices are in the area of r = 0.5 [25, 39, 40]. The x-ray of the lungs shows a density measurement of the total thorax, that's why it is dependent on the air and blood content as well as extravascular lung water. Furthermore, muscle and fat layers influence a quantitative density evaluation in a x-ray of the lungs [26, 27, 28, 29, 31, 32, 39]. The lung compliance is a parameter of the active surface film in the lungs and it does not correlate with its water content [40]. EVLW as an indicator for specific ventilation modes Two studies carried out with the PULSION COLD System in the recent past, adress the choice of mode of ventilation for patients with acute respiratory insufficiency. Zeravik et al [42] found, that in patients with ARDS combined high frequency ventilation only improves oxygenation, when the patients have high lung water content. In another study it was shown, that in patients with acute respiratory failure pressure support ventilation was superior to controlled ventilation, if lung water was normal to slightly increased [43]. The results suggest, that through lung water measurement one can identify whether patients benefit from combined high frequency ventilation or rather from pre ssure supported spontaneous ventilation. An identification of this kind is not possible with conventional assessment criteria, such as oxygenation indices, compliance or with other parameters. In several studies [36, 37, 38] Schuster and co-workers examined whether consideration of EVLW value for volume management has any influence on the course of illness in intensive care patients. A positive influence was shown in all studies when the physicians treating the patients, knew the actual amount, as well as the trend of extravascular lung water. In a prospective controlled randomized study with more than 100 patients it was shown, that, by monitoring and manipulating EVLW, length of mechanical ventilation and stay in the ICU could be reduced [37]. Consideration of EVLW for circulating volume management reduces the lung edema, the days of mechanical ventilation as well as days in the intensive care.

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Relationship of ITBV to EVLW In the past few years many studies have shown that intravascular volume management of critically ill patients by volume measurement has many advantages in comparison to that of pressure management [16, 17, 18, 19, 20, 21, 22]. The level of EVLW is related to patient outcome [40], any measures to reduce EVLW are most likely to shorten ventilation days and stay in the ICU [37] and reduce possible complications (pneumonia, pneumothorax, etc.). The hydrostatic component of increased EVLW can be reduced by volume restriction. In the following diagram it is shown that below the "normal range" of ITBV one cannot reduce EVLW anymore. Therefore, ITBV representing cardiac preload, should not be driven below this “normal range” in order to avoid a further reduction of cardiac output and hence, oxygen supply to the body.

Fig. 7:

4-8

Patient management by combined use of EVLW and ITBV

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4.3.4 CARDIAC FUNCTION INDEX (CFI) Cardiac function index (CFI) is derived as the ratio of cardiac output divided by global enddiastolic volume:

CFI = CI / GEDVI

(6)

(Patho-) physiological significance of CFI The CFI is a preload independent variable reflecting the inotropic state of the heart [33, 34]. Positive inotropic stimulation will shift the CI/GEDVI-line to become steeper, reduced contractility will flatten the slope, which represents the cardiac finction index (CFI) (see figure 8) CI (l/min/m2) 10,0

normal cardiac function

7,5 normal range

5,0

Inotropics

2,5 Volume 0

200

400

600

800

1000

1200

GEDVI (ml/m 2)

Fig. 8:

Schematic relationship between global end-diastolic volume index (GEDVI) and cardiac index (CI).

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