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Less invasive methods of advanced

hemodynamic monitoring

DR GHALEB ALMEKHLAFICONSULTANT CCMPSMMC AUG 2014

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Introduction

• Hemodynamics is concerned with the forces generated in the cardiovascular system

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1-Intravascular volume

2-Myocardial contraction 3- heart rate

3-Vasoactivity

4 factors that affecting the hemodynamic conditions

C.O.= HR x Stroke Volume (60-130 Ml/beat)

Stroke Volume has three components 1. Preload 2. Afterload

3.Contractility

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Hemodynamic Monitoring Truth

•No monitoring device will improve outcome, Unless coupled to a treatment, which improves outcome.

Pinsky & Payen. Functional Hemodynamic Monitoring, Springer, 2004

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Classic Hemodynamic Monitoring methods

Noninvasive HemodynamicMonitoring methods:• Pulse Rate and quality• Blood Pressure• Skin temperature/color• Capillary Refill• Pulse oximeter• Mentation• UOP-Normal is 1ml/kg/h

Invasive and less invasive HemodynamicMonitoring methods:• PAC-CO• CVL-CVP• ARTERIAL CATHETER-IBP

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Advanced hemodynamic assessment methods

COMMON TECHNEQUES• Pulse contour analysis and

transpulmonary dilution techneques• Electrical bioimpedance/ bioreactance• esophageal Doppler• Echocardiogram • Partial carbon dioxide rebreathing :NICO• others

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PULSE WAVE-CONTOUR

• Detected by the use of an arterially placed catheter with a pressure transducer, which can measure pressure tracings on a beat-to-beat basis

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CO MEASURMENT BY PCA

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Factors affecting accuracy of PCA

arterial pressure waveform are affected by• vascular compliance,• aortic impedance • Peripheral arterial resistance.• Technical factors(i.e. eliminating damping or increased tubing

resonance , zeroing)• severe arrhythmias• the use of an intra-aortic balloon pump precludes adequate performance

of the devices.• periods of hemodynamic instability, i.e., rapid changes in vascular

resistance. Is a problem for uncalibrated pulse pressure analysis. So frequent re-calibration for accurate cardiac output estimation in these situations is mandatory

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CALIBRATION FOR PCA

• Because vascular impedance varies between patients, it had to be measured using another modality to initially calibrate the PCA system

• The calibration method is transpulmonary thermodilution for PiCCO (need cvp and a-line) and VolumeViewTM

• The LiDCO plus: requires calibration using the transpulmonary lithium indicator dilution technique, which can be performed via a peripheral venous line(need a-line)

• FLOTRAC/VIGILEO doesn't need calibration because it estimate cardiac output by the standard deviation of pulse pressure sampled during a time window of 20 seconds

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PCA/TPD

• Advantages– Almost continuous data of CO / SV / SV variation– Provide information of preload and EVLW– Provide many other parameters which has potential clinical

utilities

• Disadvantages– STILL invasive but less than PAC– arterial pulse signal is affected by many factors

• Arrhythmia• Damping• Use of IABP

Need calibration

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Transpulmonary thermodilution-PICCO and Edward / Volume ViewTM

• .

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Tb

injection

t

dtT

KV)T(TCO

b

iibTDa

Transpulmonary thermodilution:

1-Cardiac Output estimation/ calibration

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

CO Calculation: Area under the

Thermodilution Curve

After central venous injection of the indicator, the thermistor at the tip of the arterial catheter measures the downstream temperature changes. Cardiac output is calculated by analysis of the thermodilution curve using a modified Stewart-Hamilton algorithm:

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LiDCO– LiCl: 0.002mmol/l injected into

central vein (peripheral administration possible as well)

– Arterial plasma conc. measured by withdrawing blood across lithium selective electrode at 4ml/min

– CO calculated from Li dose and area under primary concentration-time curve before re-circulation

PCV is packed cell volume which may be calculated as hemoglobin concentration (g/dl) / 34

Cardiac Output = (Lithium Dose x 60)/(Area x (1-PCV))

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Advanced Thermodilution Curve Analysis

Transpulmonary thermodilution:

2-Volumetric parameters derivation

Mtt: Mean Transit time

time when half of the indicator has passed the point of detection in the artery

DSt: Down Slope time

exponential downslope time of the thermodilution curve

For the calculations of volumes…

ln Tb

injectionrecirculation

MTtt

e-1

DSt

Tb

…are important.

…and…

All volumetric parameters are obtained by advanced analysis of the thermodilution curve:

ITTV=CO X MTtPTV=CO X DSt

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RAEDV

Thermodilution curve measured with arterial catheter

CV Bolus Injection

LAEDV LVEDVRVEDV

Right Heart Left Heart

Lungs

After injection, the indicator passes the following Intrathoracic compartments:

The intrathoracic compartments can be considered as a series of “mixing chambers” for the distribution of the injected indicator (intrathoracic thermal volume).

ITTV

PTV

The largest mixing chamber in this series are the lungs, here the indicator (cold) has its largest distribution volume (largest thermal volume).

Transpulmonary thermodilution: Volumetric parameters calculation

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ITTV = CO * MTt

PTV = CO * DSt

ITBV = 1.25 * GEDV

EVLW* = ITTV - ITBV

GEDV = ITTV - PTV RAEDV RVEDV LAEDV LVEDV

RAEDV RVEDV LAEDV LVEDVPBV

RAEDV RVEDV LAEDV LVEDVPTV

PTV

EVLW*

EVLW*

Calculation of thermal volumes

Index of Left Ventricular Contractility*

t [s]

P [mm Hg]

dPmx* =dP/dtmax of arterial pressure curve

dPmx* represents left ventricular pressure velocity increase and thus is a parameter of myocardial contractility

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

The PiCCO measures the following parameters:

Pulse Contour Parameters• Pulse Contour Cardiac Output

PCCO• Arterial Blood Pressure

AP• Heart Rate

HR• Stroke Volume

SV• Stroke Volume Variation

SVV• Pulse Pressure Variation

PPV• Systemic Vascular Resistance

SVR• Index of Left Ventricular Contractility

dPmx*

Parameters measured with the PiCCO-Technology

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Normal ranges

PARAMETER RANGEUNIT

CI 3.0 – 5.0l/min/m2

SVI 40 – 60ml/m2

GEDI 680 – 800ml/m2

ITBI 850 – 1000ml/m2

ELWI* 3.0 – 7.0ml/kg

PVPI* 1.0 – 3.0

SVV 10

%

PPV 10 %

GEF 25 – 35%

CFI 4.5 – 6.51/min

MAP 70 – 90mmHg

SVRI 1700 – 2400dyn*s*cm-5*m

What is the current situation?.………..……..………….Cardiac Output!

What is the preload?.……………….....…Global End-Diastolic Volume!

Will volume increase CO?....………...……….Stroke Volume Variation!

What is the afterload?……………..…..Systemic Vascular Resistance!

Are the lungs still dry?...…….……...…..….Extravascular Lung Water!*

What about the contractility?........................ dPmx* LV pressure velocity

Clinical application

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Decision tree for hemodynamic / volumetric monitoring

CI (l/min/m2)

GEDI (ml/m2)or ITBI (ml/m2)

ELWI* (ml/kg)(slowly responding)

>3.0<3.0

>700>850

<700<850

>700>850

<700<850

ELWI* (ml/kg)

GEDI (ml/m2)or ITBI (ml/m2)

CFI (1/min)or GEF (%)

<10 >10 <10 <10 <10>10 >10 >10

V+ V+! V+!V+Cat Cat

OK!

V-

>700>850

700-800850-1000

>4.5>25

>5.5>30

>4.5>25

700-800 850-1000

Cat

>5.5>30

>700>850

700-800 850-1000

700-800 850-1000

10 10 10 10

V-

V+ = volume loading (! = cautiously) V- = volume contraction Cat = catecholamine / cardiovascular agents** SVV only applicable in ventilated patients without cardiac arrhythmia

>700>850

<10Optimise to SVV** (%)<10 <10 <10

RESULTS

TARGET

THERAPY

1.

2. <10 <10 <10 <10

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A protocol for resuscitation of severe burn patients guided by transpulmonary thermodilution and lactate levels

A decision tree for the adjustment of fluid and catecholamine therapy according to a permissive hypovolemia protocol with lower preload targets and lactate measurements to ensure tissue perfusion is shown

Sánchez et al. Critical Care 2013, 17:R176

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In conclusion

• Hemodynamic monitoring enable early detection of change in patient’s conditions

• New techniques provide reasonably good results and less invasive

• Always correlate the readings / findings with clinical pictures in order to provide the best treatment options

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HEMODYNAMIC MONITORING COURSE AND WORKSHOP

• One-day course• 7 lectures• 4-station workshop• 8 CME hours• On September 11/every 3 months• In PSMMC rec. center

questions?