Cardiac output monitoring can be done using invasive, minimally invasive, and non-invasive methods. Invasive methods like pulmonary artery catheter use thermodilution or dye dilution to directly measure cardiac output but carry risks. Minimally invasive methods like LiDCO, PiCCO, and FloTrac use pulse contour analysis after initial calibration. Non-invasive options include thoracic bioimpedance and echocardiography. The choice of monitoring method depends on factors like accuracy, ease of use, risks, and costs. While goal-directed therapy using cardiac output monitoring may improve outcomes in some high-risk patients, large trials found no clear benefit of pulmonary artery catheters on mortality.

1. CARDIAC OUTPUT
MONITORING
Dr. Ananya Nanda

2. SECTIONS…
• Definition
• Features of an ideal monitor
• Types of monitoring CO
• Fick s principle and its application
• Thermodilution and dye dilution techniques
• Minimally invasive methods – PICCO, LIDCO, FLOTRAC, TEE, OD
• Non invasive methods NICO, TTE, MODELFLOW, BIOIMPEDANCE
• Summary

3. CARDIAC OUTPUT::: Reflects efficiency of the CVS
• The CO is the amount of blood delivered to the tissues by the heart
each minute.
• It is a measurement that reflects the status of the entire circulatory
system, not just the heart, because it is governed by autoregulation
from the tissues.
• The CO is equal to the product of the SV and the heart rate (HR).
Preload, afterload, HR, and contractility are the major determinants
of the CO.
• It is the determinant of global oxygen transport to the body

4. WHY and WHEN should we measure?
• In critically ill
• High risk surgical patients (in whom large fluid shifts are
expected) with bleeding and hemodynamic instability
Low Cardiac Output Leads To Significant Morbidity And
Mortality
• Allows us to assess the blood flow to the tissues, and provides
information on how to best support a failing circulation ins a
goal directed therapy
• Clinical Assessment of cardiac output is unreliable/ inaccurate

5. An Ideal Cardiac Output Monitor
• Safe, accurate and repetitive - Reliable during various physiological
states
• Quick and easy to use both in terms of set-up and interpretation of
information
• Operator independent

6. Methods of CO Monitoring
INVASIVE MINIMALLY INVASIVE NON INVASIVE
1. PA Catheter
• Dye dilution
technique
• Thermodilution
technique
1. Lithium dilution CO
(LiDCO)
2. Pulse contour analysis
(PiCCO)
3. FloTrac
4. Esophgeal Doppler (ED)
5. Transesophgeal echo
(TEE);
1. Partial gas rebreathing
(NICO)
2. Thoracic bioimpedance/
bioreactance
3. endotracheal cardiac output
monitor (ECOM)
4. TTE
5. Photoelectric
plethysmography

7. FICK s METHOD: gold standard
PRINCIPLE - the total
uptake (or) release of a
substance by an organ is
the product of the blood
flow through the organ
and the arteriovenous
concentration difference
of the substance .

8. Indicator dilution method
• Flowing blood can dilute the
substances introduced into
the circulation
• A known amount of a dye, is
injected into the right atrium.
• The amount of indicator
detected at the downstream
point is equal to the product
of CO and the change in
indicator concentration over
time.

9. Indicator dilution method
• The concentration of the dye is recorded as the dye passes through
one of the peripheral arteries, giving a curve.
Stewart–Hamilton equation
• Cold Saline
• ICG
• Lithium Ions

11. Thermodilution Method
• the indicator- cold
saline/dextrose.
• Affected by the phases of
respiration.
• The thermistor records
the change in blood
temperature with time
and uses it to records and
displays a
temperature-time curve/
Thermo dilution curve

12. • Variations in the
speed of cold water
injection can result in
altered measurement.
AUC area under
thermodilution curve
m0 = amount (or mass)
of injected cold saline

13. Modified Stewart-Hamilton Conservation Of Heat
Equation

14. • The degree of change in temperature is inversely proportional to cardiac
output.
• The higher the cardiac output, the faster he blood flow and the shorter and
steeper the thermodilution curve.
• In low cardiac output, the curve is slurred and lazy.
• Even more so in tricuspid regurgitation.

15. MEASUREMENT CONSIDERATIONS
The position of the pulmonary artery catheter
Volume and temperature of the injectate
The phase in the respiratory cycle
The patient’s body position
 Effects of concomitant intravenous infusions
 the effect of positive end-expiratory pressure
 TDCO measurements have a 10% error
Some catheters have a
heating filament near
the tip, which heats
automatically every 3
minutes, to derive
continuous cardiac
output measurement

16. Method
Principle Advantages Disadvantages
Invasive
Pulmonary
artery
catheter
(PAC)
Stewart-Hamilton equation
: the rate of blood flow is
inversely proportional to the
change in temperature over
time.
•Very accurate
•Clinical benefit in
monitoring multi-
factorial shock
states and cardiac
cases
Risk of:
•Dysrhythmias
•Cardiac perforation
•Tamponade
•Pneumothorax
•Valve damage
•Infection
•Emboli
PACMAN trial showed 10% incidence of complications, ESCAPE trial 5%.
ESCAPE trial demonstrated functional improvement with PAC guided therapy used in patients
with congestive heart failure.
The evidence
• No effect on mortality, LOS, or cost of care in either general ICU or high risk surgical patients
• No effect on surgical outcomes when used preoperatively to optimise haemodynamics.

17. Minimally Invasive Techniques
• Lithium dilution CO (LiDCO) - lithium dilution
• Pulse contour analysis CO - transpulmonary thermodilution
• FloTrac®/Vigileo® system and MostCare® require no external
calibration.
• Esophgeal Doppler (ED),
• transesophgeal echocardiography (TEE)

18. Mechanism
All of these methods are based on the Morphology Of The Arterial
Pressure Curve.
It is therefore important to obtain a precise curve morphology.

19. Pulse Contour Analysis - Principle
t [s]
P [mm Hg]
Area under
pressure curve
Shape of
pressure curve
PCCO = cal • HR •


Systole
P(t)
SVR
+ C(p) •
dP
dt
( ) dt
Aortic
compliance
Heart
rate
Patient-specific calibration factor
(determined by thermodilution)
• Arterial pressure waveform determined by interaction of
stroke volume and SVR.
• based on the principle that area under the systolic part
of the arterial pressure waveform is proportional to the
SV.

20. Limitations
Values can be affected by:
• Buffering of the arterial curve
• insufficient zeroing
• Furthermore, the analysis of pulse pressure is of limited accuracy
during periods of hemodynamic instability, as for example in the rapid
changes in vascular resistance found in septic patients and in cases of
liver dysfunction
• Arrhythmias
• IABP
• Severe aortic regurgitation

21. Lithium Dilution Cardiac Output system (LiDCO plus)
• Uses a peripheral lithium indicator sensor
• acceptable accuracy----- frequent calibrations
• less invasive that the PiCCO system, since it requires no central venous access
• CO is calculated based on Li dose and area according to the concentration time
circulation.
• A bolus of lithium chloride is injected into venous line and arterial concentration is
measured by withdrawing blood across disposable lithium sensitive sensor
containing an ionophor selectively permeable to Li.
• Contraindications
• chronic lithium use,
• recent NDNMB,
• early pregnancy

22. Can calculate a number of derived parameters:
• systolic pressure variation,
• pulse pressure variation,
• cardiac index,
• stroke volume,
• stroke volume index,
• stroke volume variation,
• systemic vascular resistance and
• systemic vascular resistance index.

23. PICCO system
• It requires both central venous (femoral or internal jugular) and arterial
cannulation (femoral/radial).
• it combines pulse contour analysis with the transpulmonary
thermodilution CO measurement
• It requires manual calibration every 8 h and hourly during
hemodynamic instability.

24. • can calculate pulse pressure variation (PPV) stroke volume variation (SVV)
• very sensitive preload parameters
• indicate the point of the patient on the Frank–Starling curve
• SVV value of 9.5% or more, will increase SV by at least 5% in response to a
100-ml volume load, with a sensitivity of 79% and specificity of 93%.'
Volemic Status Of
Ventilated Patients.
Extravascular Lung Water
(EVLW)- Lung Edema And
Vascular Permeability
Optimize Use Of
Vasoactive Drugs, Diuretics
Or Dialysis

25. ERNEST
STARLING
OTTO FRANK

26. FloTrac / VIGILEO
system (2005)
• pulse contour analysis device 2005
• no external calibration, operator independent
and easy to use.
• Good arterial waveform quality is a prerequisite.
• Various studies have validated the efficacy of
FloTrac with PAC and find good correlation

27. • Accuracy is affected in patients with significant arrhythmias, IABP or morbid
obesity.
• In patients with low SVR, undergoing liver transplantation or septicemia it is
not found as accurate as PAC
• When the cardiac index (CI) was <2.2, the data demonstrated that the FV
was outperformed by PAC in both empty (30.8%, n = 13 vs. 57.1%, n = 14,
respectively) and PSF states (66%, n = 3 vs. 50%, n = 4, respectively).

28. Pressure recording analytic method(PRAM)
• a new, less invasive technique allowing beat-by-beat stroke volume
monitoring from the pressure signals recorded in femoral or radial
arteries

29. TEE (Trans Esophageal Echocardiography)
• Doppler technique is used to measure CO by Simpson’s rule measuring
SV multiplied by HR.
• Flow is measured by area under the Doppler velocity waveform that
gives VTI
• Measurement can be done at the level of pulmonary artery, mitral or
aortic valve.
• TEE views used for measurement are
• midesophageal aortic long axis view and
• deep transgastric long axis view with pulsed and continuous wave Doppler respectively

30. Trans Esophageal Echocardiography (TEE)
• an important tool for the
assessment of cardiac structures,
filling status and cardiac
contractility
• by measuring both the velocity
and the cross-sectional area of
blood flow in the LVOT or aorta or
PA.
• Flow = CSA X Velocity
• SV= flow X ET ( Systolic Ejection
time)
• CO=SV X HR

31. Esophageal Doppler
FLOW= CSA X Vti
• Major limiting factor is that it measures flow only in
descending thoracic aorta which is 70% of total flow.
• Values calculated from these are stroke volume (SV)
flow-time corrected (FTc) and cardiac output (CO).
• IT provides
• Heart Rate (HR), Stroke Distance (SD), Maximum Acceleration
(MA),
• Flow-time (FT) Peak Velocity (PV)
Using manual input of age, weight and height; body surface area (BSA) and body mass
index (BMI), cardiac index (CI) and stroke volume index (SVI or SI) can be calculated.

32. • IABP
• Severe Coarctation
• Known Pharyngo-oesophageal Pathology
• Oesphagectomy
Contra-indications

33. NON INVASIVE METHODS
• Partial Gas Rebreathing
• Thoracic Bioimpedance
• Bioreactance
• The Modelflow- FINGER PROBE Based CO Monitor
• TTE/ USG

34. NON INVASIVE METHODS :Partial gas rebreathing
 known as the NICO system
uses indirect Fick’s principle to calculate CO.
At steady state, the amount of CO2 entering the lungs via the pulmonary
artery is proportional to the CO and equals the amount exiting the lungs
via expiration and pulmonary veins.
CO2 Produced per min
CO= -------------------------------------
PvCO2- PaCO2
It is used in intubated patients under mechanical ventilation.

35. THORACIC BIOIMPEDANCE
Based on the hypothesis by considering thorax as a cylinder perfused
with fluid with specific resistivity.
 Electrodes six in number are placed (two on either side of neck and
four in lower thorax) on the patient and the resistance to current
flowing from the outermost to innermost electrodes is measured.
A low-grade electrical current, from 2 - 4 mA is emitted, and
received by the adjacent electrodes
 Impedance to the current flow produces a waveform
 Changes in CO will change the amount of aortic blood and will be
reflected in a change TEB

36. BioReactance
Method used by the NICOM®
Analyzes the changes in amplitude and frequency of the electrical
impulses as they course through the chest.
 Advantages
• significant reduction of effect of electrical interferences, patient
movements or positioning, or displacement of the electrodes, which
can give rise to data error.

38. The Modelflow- FINGER PROBE based CO monitor
• Modelflow-Nexfin® system
• analyzes pulse pressure noninvasively using photoelectric plethysmography
in combination with an inflatable finger cuff.
PRINCIPLE
Cardiac output is calculated through continuous monitorization of arterial
pressure and analysis of pulse wave morphology, based on the study of the
area of the systolic pressure wave and on the Windkessel triple elements
model individualized for each patient (Modelflow method).
• The measurements obtained include continuous CO, SV, SVR and left
ventricle contractility index.

39. TTE
• can be used to estimate cardiac output by
direct visualisation of the contracting heart in
real time.
• safe and most reliable cardiac output
monitors in the critically ill.
• Using transthoracic echocardiography four
views are obtained (parasternal long axis,
parasternal short axis, apical, and subcostal
• Helps in assessment of ventricular function
and size of cardiac chambers.

41. Summary
• The choice of one device or other should be determined by the
experience of operator, facility of use and interpretation of the
results, the precision of the system, and its cost-effectiveness.
• Monitoring of the critical patient must be global, with
multiparametric monitoring combining the hemodynamic parameters
and the metabolic data regards to oxygen transport and consumption,
with the purpose of optimizing tissue perfusion and improving
survival of the critically ill patient.

42. Thank you

43. • PAC-MAN trial failed to show any benefit or harm with the use
of PAC.
• ESCAPE TRIAL IN heart failure patients--- Addition of the PAC to
careful clinical assessment increased anticipated adverse events, but
did not affect overall mortality and hospitalization.