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HEMODYNAMIC MONITORING Part 2 Dr.Gagan Brar MD,IDCCM EDIC

hemodynamic monitoring

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Page 1: hemodynamic monitoring

HEMODYNAMIC MONITORING

Part 2Dr.Gagan BrarMD,IDCCMEDIC

Page 2: hemodynamic monitoring

Monitoring of physiologic variables comprises an integral part of the care of the critically ill patient

Assists the intensivist in both diagnostic and treatment strategies.

Debate regarding the usefulness and safety of invasive hemodynamic monitoring in the intensive care unit (icu).

Several studies have shown improved outcomes from hemodynamic monitoring in high-risk surgical patients, but there is conflicting evidence as to benefits in the critically ill medical patient

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3

Standard Monitoring

Monitoring

Respiration Rate

NIBP

ECG

Temperature

Urine Production

Oxygen Saturation

Blood Circulation(clinical assessment)

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• will fluid increase perfusion to end organs, or will it worsen pulmonary or systemic edema?

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• oxygen delivery• • Organ perfusion

TOO LESS

• Too much interstitial fluid• Too much lung water• Poor outcomes

TOO MUC

H

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CVP = 8 – 12 mm Hg

CONTINUE AS LONG AS THERE IS HAEMODYNAMIC IMPROVEMENT

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Does it improve organ perfusion?

By how much?

For how long?

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LIB CON-1000

0

1000

2000

3000

4000

5000

6000

7000

6992

-136

Series1

Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006 Jun 15;354(24):2564-75.

FACTT trial – fluid conservative (-136) Vs liberal (6992 ml) in the first 7 days

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FACTT – VENTILATOR FREE DAYS

Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006 Jun 15;354(24):2564-75.

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CUMULATIVE FLUID BALANCEWAS MOST LETHAL!!

Sepsis in European intensive care units: results of the SOAP study. Crit Care Med. 2006 Feb;34(2):344-53.

In a multicentre European observational study, a CUMULATIVE FLUID balance at 72 hours was among the strongest predictors of death. 24 European countries, 198 ICUs, 3147 adult patients. Cumulative fluid balance in the first 72 hrs

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RRT Fluid overload 59.2%

RRT No fluid overload 31.4%

Fluid overload is associated with an increased risk for 90-day mortality in critically ill patients with renal replacement therapy: data from the prospective FINNAKI study. Critical Care 2012, 16:R197

Prospective observational study of 296 RRT treated patients. Fluid overload – gain in more than 10% body weight at time of RRT. Fluid overload led to increased 90 day mortality; odds ratio: 2.6

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<0 0 to 5% 5 to 10% 10 to 15% >15%0

10

20

30

40

50

60

70

Series1

Fluid overload is associated with an increased risk for 90-day mortality in critically ill patients with renal replacement therapy: data from the prospective FINNAKI study. Critical Care 2012, 16:R197

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Pressure that dilates the ventricle = intraventricular – pleural pressure (what we can measure at best is intra-cavity pressure)

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• Static measurements have failed as a meaningful endpoint for fluid resuscitation

• Rapid fluid bolus is a reasonable diagnostic and potentially therapeutic option

• Has the potential to cause harm • May delay institution of appropriate therapy

• . GOALS SHOULD BE BASED IN SCIENCE AND SUPPORTED BY EVIDENCE.

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CARDIAC OUTPUT

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cardiac output • first measured by the German physician and physiologist Adolf Fick 1870 using

an oxygen uptake method.

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The Fick method was later modified in 1897 by Stewart to use a continuous saline infusion and then in 1928 by Hamilton to use abolus injection of dye technique .

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Monitoring • Invasive• pulmonary artery catheter

Non-invasive• Bio impedence cardiac output monitoring• Partial carbon dioxide re breathing cardiac output monitoring

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Minimally invasive• oesophageal Doppler

• Transpulmonary thermodilution and pulse contour analysis PiCCO LiDCO• Pulse contour analysis, FlowTrac , PRAM• Ultrasound dilution, COstatus

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Pulse Index Continuous Cardiac Output(PiCCO)

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PiCCO Technology is a combination of transpulmonary thermodilution and pulse contour analysis

Principles of Measurement

Left HeartRight Heart

Pulmonary CirculationLungs

Body CirculationPULSIOCATHPULSIOCATH

CVC

PULSIOCATH arterial thermodilution catheter

central venous bolus injection

Introduction to the PiCCO-Technology – Function

central venous injection of a cold bolus and detection of the temperature course in a peripheral large artery (femoral, axillary, brachial) through a special thermodilution catheter.

calibrated from the results of the thermodilution measurement and delivers continuous haemodynamic parameters in contrast to intermittent thermodilution.

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Bolus injection

concentration changes over time(Thermodilution curve)

After central venous injection the cold bolus sequentially passes through the various intrathoracic compartments

The temperature change over time is registered by a sensor at the tip of the arterial catheter

Introduction to the PiCCO-Technology – Function

Left heartRight heart Lungs

RA RV LA LVPBV

EVLW

EVLW

Principles of Measurement

The individual cardiac chambers and the lung with the extravascular lung water are mixing chambers in which the cold bolus is distributed

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Tb x dt(Tb - Ti) x Vi

x K

Tb

Injection

t

∫ D=COTD a

Tb = Blood temperatureTi = Injectate temperatureVi = Injectate volume∫ ∆ Tb

. dt = Area under the thermodilution curveK = Correction constant, made up of specific weight and specific heat of blood and injectate

The CO is calculated by analysis of the thermodilution curve using the modified Stewart-Hamilton algorithm

Calculation of the Cardiac Output

Various volume parameters can be calculated from the thermodilution curve, which is recorded via the thermodilution catheter (PiCCO catheter).

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The area under the thermodilution curve is inversely proportional to the CO.

36,5

37

5 10

Thermodilution curves

Normal CO: 5.5l/min

Introduction to the PiCCO-Technology – Thermodilution

36,5

37

36,5

37

Time

low CO: 1.9l/min

High CO: 19l/min

Time

Time

Temperature

Temperature

Temperature

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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

Recirculation

t

e-1

Tb

From the characteristics of the thermodilution curve it is possible to determine certain time parameters

Extended analysis of the thermodilution curve

Introduction to the PiCCO-Technology – Thermodilution

Injection

In Tb

MTt DSt

Tb = blood temperature; lnTb = logarithmic blood temperature; t = time

time from injection to the point at which the thermodilution curve has fallen to 75% of its maximum. Downslope time in which TD curve falls from 75% of its max to 25% of its maximum.mixing behaviour of the indicator in the largest mixing chamber

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Pulmonary Thermal Volume

PTV = Dst x CO

By using the time parameters from the thermodilution curve and the CO ITTV and PTV can be calculated

Calculation of ITTV and PTV

Introduction to the PiCCO-Technology – Thermodilution

Recirculation

t

e-1

Tb

Injection

In Tb

Intrathoracic Thermal Volume

ITTV = MTt x CO

MTt DSt

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Intrathoracic Compartments (mixing chambers)

Introduction to the PiCCO-Technology – Function

Pulmonary Thermal Volume (PTV)

Intrathoracic Thermal Volume (ITTV)

Total of mixing chambers

RA RV LA LVPBV

EVLW

EVLW

Largest single mixing chamber

ITTV : all four cardiac chambers, the pulmonary circulation and the extravascular lung water forms the total intrathoracic thermal volume.

The largest single mixing chamber in this system is the pulmonary thermal volume, which consists of the blood volume of the pulmonary circulation and the extravascular lung water.

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Pulmonary Thermal Volume (PTV)

Intrathoracic Thermal Volume (ITTV)

Calculation of ITTV and PTV

Einführung in die PiCCO-Technologie – Thermodilution

ITTV = MTt x CO

PTV = Dst x CO

RA RV LA LVPBV

EVLW

EVLW

PTV represents the largest single mixing chamber in the thorax, the pulmonary thermal volume, which consists of the blood volume of the pulmonary circulation (pulmonary blood volume, PBV) and the extravascular lung water (EVLW).

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GEDV is the difference between intrathoracic and pulmonary thermal volumes

Global End-diastolic Volume (GEDV)

Volumetric preload parameters – GEDV

RA RV LA LVPBV

EVLW

EVLW

ITTV

GEDV

PTV

Introduction to the PiCCO –Technology – Thermodilution

the total blood volume in all 4 cardiac chambers

that gives information about the filling condition of the heart and thus about cardiac preload.

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Volumetric preload parameters – ITBV

Intrathoracic Blood Volume (ITBV)

GEDV

ITBV

PBVRA RV LA LVPBV

EVLW

EVLW

Introduction to the PiCCO –Technology – Thermodilution

ITBV is the total of the Global End-Diastolic Volume and the blood volume in the pulmonary vessels (PBV)

the total blood volume present in the heart and pulmonary circulation

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Transpulmonary Thermodilution

The pulse contour analysis is calibrated through the transpulmonary thermodilution and is a beat to beat real time analysis of the arterial pressure curve

Calibration of the Pulse Contour Analysis

Introduction to the PiCCO-Technology – Pulse contour analysis

Injection

Pulse Contour Analysis

T = blood temperature t = timeP = blood pressure

COTPD= SVTD

HR

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PCCO = cal • HR •P(t)SVR + C(p) • dP

dt( ) dt

Cardiac Output

Patient- specific calibration factor (determined by thermodilution)

Heart rate Area under the pressure curve

Shape of the pressure curve

Aortic compliance

Systole

Introduction to the PiCCO-Technology – Pulse contour analysis

Parameters of Pulse Contour Analysis

Besides the area under the pressure curve and other factors, calculation of the continuous PiCCO pulse contour cardiac output also involves the aortic compliance measured by thermodilution, which represents an important advantage compared to systems that cannot be calibrated.

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SVmax – SVminSVV =

SVmean

SVmax

SVmin

SVmean

The Stroke Volume Variation is the variation in stroke volume over the ventilatory cycle, measured over the previous 30 second period.

Parameters of Pulse Contour Analysis

Introduction to the PiCCO-Technology – Pulse Contour Analysis

Dynamic parameters of volume responsiveness – Stroke Volume Variation

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PPmax – PPminPPV =

PPmean

The pulse pressure variation is the variation in pulse pressure over the ventilatory cycle, measured over the previous 30 second period.

Parameters of Pulse Contour Analysis

Introduction to the PiCCO-Technology – Pulse Contour Analysis

Dynamic parameters of volume responsiveness – Pulse Pressure Variation

PPmax

PPmean

PPmin

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Contractility is a measure for the performance of the heart muscle

Contractility parameters of PiCCO technology:

- dPmx (maximum rate of the increase in pressure)

- GEF (Global Ejection Fraction)

- CFI (Cardiac Function Index)

Contractility

Introduction to the PiCCO-Technology – Contractility parameters

kg

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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.

Calculation of Extravascular Lung Water (EVLW)

Introduction to the PiCCO –Technology – Extravascular Lung Water

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Differentiating Lung Oedema

PVPI = Pulmonary Vascular Permeability Index

• 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)

EVLWPVPI =

PBVPBV

EVLW

Introduction to PiCCO Technology – Pulmonary Permeability

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permeability

PVPI normal (1-3) PVPI raised (>3)

Classification of Lung Oedema with the PVPI

Difference between the PVPI with hydrostatic and permeability lung oedema:

Lung oedema

hydrostatic

PBV

EVLW

PBV

EVLW

PBV

EVLW

PBV

EVLW

Introduction to PiCCO Technology – Pulmonary Permeability

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EVLWI answers the question:

Clinical Relevance of the Pulmonary Vascular Permeability Index

PVPI answers the question:

and can therefore give valuable aid for therapy guidance!

How much water is in the lungs?

Why is it there?

Introduction to PiCCO Technology – Pulmonary Permeability

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Relevance of EVLW- Management

101 patients with pulmonary edema were randomized to a pulmonary artery catheter (PAC) management group in whom fluid management decisions were guided by PCWP measurements and to an Extravascular Lung Water (EVLW*) management group using a protocol based on the bedside measurement of EVLW *.ICU days and ventilator-days were significantly shorter in patients of the EVLW* group.Mitchell et al, Am Rev Resp Dis 145: 990-998, 1992

22 days 15 days9 days 7 days

* *Ventilation days ICU daysn=101

EVLW* groupPAC groupEVLW* groupPAC group

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Normal rangesParameter Range Unit

CI 3.0 – 5.0 l/min/m2

SVI 40 – 60 ml/m2 GEDI 680 – 800 ml/m2

ITBI 850 – 1000 ml/m2

ELWI* 3.0 – 7.0 ml/kgPVPI* 1.0 – 3.0 SVV 10 %PPV 10 %GEF 25 – 35 %CFI 4.5 – 6.5 1/minMAP 70 – 90 mmHgSVRI 1700 – 2400 dyn*s*cm-5*m

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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 IndexCFI

• Global Ejection FractionGEF

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 ContractilitydPmx

Parameters measured with the PiCCO-Technology

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Lithium Dilution Monitoring Combines the techniques of lithium dilution (lidco and lidcoplus) and pulse contour analysis (pulseco)

Small dose of lithium is injected into a peripheral vein and an ion selective electrode is attached to a peripheral arterial line

The area under the curve of a plot of lithium concentration against time allows accurate calculation of the cardiac output.

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PulseCO is calibrated

provides ‘beat-to-beat’ cardiac output measurement

uses catheters which are likely to be already in place

The total dose of lithium is small and is clinically insignificant.

Calibration is recommended every 8 hours, or after any significant change in the patient’s clinical condition.

The system cannot be used for patients taking lithium and those who have recently received vecuronium or atacurium.

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• Uses the arterial pressure waveform to Measure COO

• The difference over other monitors (such as the LiDCO®) is that it does not need to be calibrated with an indicator

• Application of advanced statistical principles to the arterial pressure tracing Result in the creation of a proprietary algorithm

• Recalibrates itself constantly

• By measuring the arterial pressure over a 20 s period at 100 Hz, the• system obtains 2000 data points for analysis

• The standard deviation of these points is then compared with empirical data stored in the proprietary algorithm of the software correlating the standard deviation of the arterial pressure measurements with the appropriate SV.

• The FloTrac® is also able to account for changes in arterial compliance which allows for the device to remain accurate and reliable during periods when CO, vasomotor tone or both are changing.

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Studies evaluating the 1st -generation and 2nd generation

FloTrac showed poor agreement compared with

intermittent thermodilution,

their accuracy remained clinically

unacceptable.

The 3rd generation software claims to

have overcome these problems

do not show improved accuracy in comparison with

older versions

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Partial Co2 rebreathing fick monitoring (NICO)

• The NICO monitor uses a rearrangement of the fick equation for CO2 elimination.

• Can only be used for patients who are intubated• The partial rebreathing technique gives a better approximation of cardiac output in patients who are less critically ill and have normal alveolar gas exchange

• Best suited for monitoring trends in critically ill patients with stable lung function rather than diagnostic interpretation

Gama de Abreu M, Quintel M, Ragaller M, et al: Partial carbon dioxide rebreathing: A reliable technique for noninvasive measurement of nonshunted pulmonary capillary bloodflow.Crit Care Med1997; 25:675–683

Jopling MW: Noninvasive cardiac output determination utilizing the method of partial CO2rebreathing. A comparison with continuous and bolus thermodilution cardiac output.Anesthesiology1998; 89:A544

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Thoracic bioimpendance• The technique depends on the change in bioimpedance of the

thoracic cavity during systole• A series of ECG type electrodes are placed on the thorax and

neck. A small, non-painful current is passed and measurements made

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Oesophageal doppler• Was first described in 1971 and later refined in 1989

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PRINCIPLE• Flow in a cylinder is equal to the area of the cross-section of the

cylinder times the velocity of fluid in cylinder

• Movement of blood is pulsatile and the velocity changes with time

• The velocity can be characterized by the area under the velocity-time curve between two points in time

• area under the curve computed mathematically as the integral of the derivative of volume over time (dv/dt) from T1 to T2,

• Time integrated velocity.

• Stroke volume (sv) is calculated by multiplying the cross sectional area by the time-integrated velocity.

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The probe is approximately the size of a nasogastric tube

Doppler transducer (4 MHz continuous or 5 MHz pulsed wave, according to the type of device) at the tip of a flexible probe.

similar technique to placing a nasogastric tube

measures velocity not flow,

descending aorta only receives a portion of the cardiac output,

only an estimate of cardiac output based on descending aortic blood flow

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important consideration is the importance of positioning

To have a good approximation of velocity, the Doppler beam should bewithin 20°of axial flow

cross-sectional area of the aorta is actually dynamic and isdependent on the pulse pressure and aortic compliance

flow in the aorta is not always laminar

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Oesophageal Doppler

Ultrasound beam is directed at the descending thoracic aorta

The magnitude of Doppler shift is directly proportional to the velocity of the blood flow

Stroke volume = Mean blood velocity x Ejection time x Aortic cross-sectional area

probe inserted via nasal or oral route is advanced and rotated until characteristic descending aortic trace is obtained and optimized.

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Normal ranges  FTc: Flow Time corrected measure of cardiac preload 330 -360 milliseconds

 PV: Peak Velocity-an index of contractility

20 yrs: 90 - 120 cm/sec  50 yrs: 70 - 100 cm/sec 70 yrs: 50 -80 cm/sec

Concurrent shifts in FTc and PV indicates changes in after load

 MA: Mean Acceleration depends on the patient

 SD: Stroke Distance depends on the patient

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Narrow waveform base, decreased FTc characteristic of hypovolaemia

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Same patient after fluid resuscitation

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•Minimally invasive•Real time measurement•Rapid insertion. Results available within few minutes.•Minimal technical skill required•Short training period•Good trend monitor

Advantages

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•Interference by nasogastric tube•Dislodgement by movement. This may result in loss of signal or may result in changes in monitored values•Some patients contraindicated (eg post-oesophagectomy, oesophageal injuries)•Absolute values of cardiac output not very accurate

Disadvantages

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Ballard C, Cohen Y, Fosse JP, et al: Haemodynamic measurements (continuous cardiac output and systemic vascular resistance) in critically ill patients: Transoesophageal Doppler versus continuous thermodilution.Anaesth Intensive Care1999; 27:33–37

Valtier B, Cholley BP, Belot JP, et al: Noninvasive monitoring of cardiac output in critically ill patients using transesophageal Doppler. Am J Respir Crit Care Med1998; 158: 77–83

Madan AK, UyBarreta VV, Shaghayegh AW, et al: Esophageal Doppler ultrasound monitor versus pulmonary artery catheter in the hemodynamic management of critically ill surgical patients.J Trauma1999; 46:607–611

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Why do we need dynamic indices???

To determine if a patient will be preload responsive before the

volume is given

Rely on the changing physiology of heart lung interactions to

determine whether a patient will benefit

from increased preload

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PHYSIOLOGIC RATIONALE OF DYNAMIC INDICES

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Wall stress at the end of diastole

Direct measurement of wall stress in vivo is difficult; end diastolic volumes or pressures have been used as proxies

significant limitations

An accurate measure of preload at a point in time does not necessarily reflect preload responsiveness

PRELOAD

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Frank-Starling curve

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Fluid administration does not always result in cardiac output enhancement.

This comes from the curvilinearity of the frank–starling relationship:

If the heart is operating on the initial and steep part of the curve,it should have some preload reserve, and any increase in cardiac preload results in an increase in stroke volume.

If the heart is operating on the distal and flat part of the frank–starling curve(absence of preload reserve), no significant increase in stroke volume is expected from volume loading.

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Assessment of PRELOAD is not assessment of PRELOAD DEPENDENCE

Stroke volume

Ventricular preload

normal heart

failing heart

preload-dependence

preload-independence

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•Dynamic indices apply a controlled and reversible preload variation and measure the hemodynamic response.

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Effects of mechanical ventilation on left and rightventricular stroke volume

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Increased intrathoracic pressure

• Compression of the vena cava• Increased right atrial pressure.

Decreased preload to the right heart because

Decrease in right ventricular (rv) preload leads to

A decrease in RV output

Decrease in pulmonary artery blood flow, LV filling, and LV

output.

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mechanisms postulated to increase LV SV variation with PPV include changes during inspiration, caused by increased

transpulmonary pressure

Increased RV afterload

Increased LV preload

Decreased LV afterload.

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The end result of these pressure changes is

LV SV increases, while

RV SV decreases during positive pressure inspiration.

The delay of pulmonary blood transit time results in decreased RV SV translating to a decreased LV SV a few heartbeats later (ie, usually during expiration)

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These phasic differences are exaggerated in the setting of hypovolemia for several reasons:

The underfilled vena cava is more collapsible

The underfilled right atrium is more susceptible to increased intrathoracic pressure

More of the lung demonstrates the physiology of West Zones 1 and 2 which effectively increases RV afterload

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Larger changes are seen when operating on the steeper portion of the Frank-Starling curve.

This increased variation in pressures between the inspiratory phase and the expiratory phase can be used to identify hypovolemia and volume responsiveness, and is

the basis for Cavallaro’s group A and B indices, including stroke volume variation (SVV) and pulse pressure

variation.

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CLASSIFICATION OF DYNAMIC INDICES OF FLUID RESPONSIVENESS

Functional hemodynamic monitoring and dynamic indices of fluid responsiveness F. CAVALLARO, C. SANDRONI, M. ANTONELLI MINERVA ANESTESIOL 2008;74:123-35

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GROUP A: Indices based on mechanical ventilation-induced variations of stroke volume and stroke

volume-derived parameters

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GROUP B: Indices based on

mechanical ventilation-induced variations of non-

stroke volume-derived parameters

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GROUP C: Indices based on preload-

redistributing maneuvers different

from standard mechanical ventilation.

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Stroke volume variation (SVV)

SVV examines the difference between the

SV during the inspiratory and

expiratory phases of ventilation, and requires

a means to directly or indirectly assess SV.

PiCCO , LiDCO and FloTrac sensor monitors

uses pulse contour analysis through a

proprietary formula to measure cardiac output

and SVV.

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Pulse Pressure Variation

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Difference between arterial systolic and diastolic pressure

the PP during inspiration with PP during expiration demonstrates the

degree to which the PP is preload-limited

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Pulse pressure variation (PPV)

Influenced by sv and the arterial compliance.

As comparison is being made during a single

respiratory cycle, change in arterial compliance

theoretically should be minimal.

Analysis of the PPV thus can be used to predict volume

responsiveness

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In mechanically ventilated patients with septic shock,

a PPV of 13% identified patients who had a greater

than or equal to 15% increase in cardiac output

in response to volume expansion with a

sensitivity of 94% and specificity of 96%

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PLETHYSMOGRAPHYpulse oximeter plethysmographic waveform differs from the arterial pressure waveform by measuring volume rather than pressure changes in both arterial and venous vessels

Examining amplitude variation between inspiration and expiration phases

Variation in the plethysmographic waveform has been referred to by many names: change in pulse oximetry plethysmography (dPOP), ventilation-induced plethysmographic variation (VPV)

VPV (VPV(%) :([Max amplitude - Min amplitude]/[(Max amplitude + Min amplitude)/2])

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Plethysmography variability index (PVI):

obtained from plethysmographic waveforms displayed on pulse oximeters .

used for the purpose of fluid responsiveness.automated measure of the dynamic change in the “Perfusion Index” that occurs during a respiratory cycle

Its advantage is that it can be automatically calculated and displayed on the screen of the pulse oximetry monitor

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•1 - no pleth variability •100 - maximum pleth variability

PVI Calculation Automated

measurement Changes in

plethysmographic waveform amplitude over the respiratory

cycle PVI is a percentage from 1 to

100%:

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Large inter- and intra-individual variation in

VPV in 14

Poor agreement between VPV and PPV

Proprietary signal processing by different

manufacturers may alter the raw data such that it interferes with

the use of the

Waveform for purposes other than oxygen

saturation monitoring. For example, the auto–gain function on most pulse oximeters will conceal amplitude

changes

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• Evidence for pulse oximetric variation? – not validated

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Respiratory variability of the inferior vena cava

The inferior cavae are distensible blood vessels whose diameters and flow vary with respiration

The IVC enters the right atrium almost immediately after crossing the diaphragm.

Extramural pressure = abdominal pressure; intramural pressure = right atrial pressure.

Steep slope at low distention and a plateau at full volume.

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In IPPV, increase in pleural pressure increases right atrial pressure

Increases transmural pressure of the IVC – increases the IVC diameter

In hypovolemic patients these diameter changes are larger than if the IVC is full (ie, on the flat part of the pressure volume curve)

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• Distensibility index of the IVC (divc) defined as (Dmax-Dmin)/Dmin and expressed as a percentage predictive of fluid responsiveness with a sensitivity of 90% and a specificity of 90%• DDivc as maximal – minimum IVC diameter divided by the mean of the two values and expressed as a percentage.DDivc of 12% predicted fluid responsiveness with a positive predictive value of 93% and negative predictive value of 92%

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Potential for predicting preload responsiveness in septic patients.

Phasic variation of svc diameter may be more accurate, as it is not influenced by intra-abdominal pressure.,

It necessitates a transesophageal approach.

Validation of these concepts in large, multicenter trials is warranted.

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• Cyclical swing in intra-thoracic pressure• Swing in IVC size means preload is along the

steep part of the Starling Curve

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IVC size variation = Max Diam – Min Diam / Mean x 100

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Cautions Regarding Cavallaro Group A And B Indices

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Requires positive pressure controlled ventilation

Sinus rhythm required. Arrhythmia or frequent extra systoles result in altered SV and invalidate these tools to predict volume responsiveness.

Require invasive arterial blood pressure

A single value never should replace clinical judgment. A high PPV value in a normotensive patient with evidence of normal tissue perfusion does not mean that person requires volume expansion

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Further investigation of these techniques in the setting of vasoactive medications is needed.

How extremes of ventilation (ie, low tidal volume, high respiratory rate, high positive end-expiratory pressure [peep]) affect group a and b indices is not yet clear

Further investigation of these indicators in the setting of the open abdomen or

Open thorax is needed before their use should be relied upon in these populations.

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Passive Leg Raising

Reversible volume

Elevating a patient’s legs allows a passive

transfer of blood from the lower part of the

body toward the central circulation.

The amount of blood transferred from the

legs is variable and has been estimated to be

between 150 to 750 ml .

During plr, shift of fluid from the lower part of the body to the thorax

results in increased cardiac output.

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Venous return = Mean Systemic Pressure – RAPPLR Increased MSP venous return RV output LV filling Acts as a brief, totally reversible fluid challenge

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Fluid responsiveness cannot be assessed based on a single

CVP, PCWP, etc

Should be based on dynamic changes in

response to change in preload

Positive pressure ventilation and SLr produce transient preload changes

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PLR can be used in spontaneously

breathing patients and in patients not

in sinus rhythm

Several studies have determined that PLR

is effective in determining fluid-

responsiveness

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The increase in preload from the maneuver is reversed completely when the legs are returned

to horizontal,

It is safe even in cases in which increasing blood volume may be harmful

Good specificity and sensitivity

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PLR induced increase of SV by 12.5%, resulted in an increase of stroke volume by 15% after fluid challenge with 500 mls.

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Increase of cardiac output or SV of greater than 12% with PLR predicted volume responsiveness.

Sensitivity and specificity of 81% and 93%, respectively.

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The hemodynamic response to PLR is rapid and transient real-time assessment of cardiac output is needed,

It is not clear how much blood is autotransfused,

How much this varies between patients and patient populations, and if the variation is significant.

Vasoconstrictors, increased intra-abdominal pressures, and elastic compression stockings all may have an impact on validity of plr; further

studies are needed to clarify these issues.

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Limits of Preload-Responsiveness

• Preload Preload-responsiveness• Preload-responsiveness Need for fluids• The means of altering preload matters

• Size of Vt, passive leg raising, spontaneous breaths

• Different measures of pressure or flow variation will have different calibrations

Pinsky Intensive Care Med 30: 1008-10, 2004

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Where does echocardiography stand?• Tool for “functional” haemodynamic monitoring• Help predict fluid responsiveness• LV, RV, valve function• Acute PE, pericardial effusion• Clots

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LVOT AREA = ∏ (3.14) X (D/2)2

Velocity – Time Integral

Distance travelled by the blood is a function of the velocity and time = velocity – time integral. Otherwise called stroke distance. VTI x area of the LVOT

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• To calculate SV : velocity across the aorta or LVOT & CSA of aorta• As velocity/flow is not constant : measured as VTI• View the heart on the 5CV • Switch on the PWD• Place the cursor or sampling volume at the level of LVOT• Ensure that line of the cursor should be in line with LVOT• Once u switch on PWD u get waveform / envelope formed by flow

across LVOT• Trace out the Evelope which will give VTI from the inbuilt software

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Stroke Vol = VTI x CSA

Measure LVOT diameterPlax viewFreeze the frame in systoleAortic leaflets will be fully open and apposed to the aortic valve

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LV systolic function• To measure EF by teicholz method,• Parasternal long axis view• Place the M mode cursor at right angles to the septum and the free

wall of the LV.• On the m mode, measure the systolic diameter and the diastolic

diameter. • Use the calculation menu on the echo machine to measure ef by

teicholz method.

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LV dysfunction• LV dysfunction common in the ICU• Ventricular performance may be markedly impaired in sepsis• EF may be unreliable because of the low SVR• Important for haemodynamic optimisation- fluid or inotrope?

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DCM WITH POOR FUNCTION

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POOR LV FUNCTION

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PSAX OF LV FAILURE

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RV dilatation/dysfunction• Massive PE, ARDS• Excessive PEEP, RV afterload increase due to other causes• RV infarction• Air, fat embolism• Sickle cell crisis• Myocardial contusion, sepsis• RVEDA/LVEDA 0.6 TO 1.0 = moderate• >1 = severe, >2 = extreme• Eye balling – as large or larger than LV on A4C

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Pulmonary embolism

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Pulmonary Artery

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Pulmonary Embolism

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PA pressure • Tricuspid jet • Measure tricuspid gradient = 4V2

• Tricuspid gradient (TG) = RVpsys – RApsys

• RVpsys = TG + RApsys

• RApsys = CVP• RVpsys = PAsys = TG +CVP• Place CWD on regurgitent Jet• Measure the depth of the waveform from baseline

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Pericardial Effusion• Echo free space around the heart • Distinguish between pericardial and pleural effusions• Cardiac tamponade

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RA CLOT

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Mitral stenosis

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