1. Cardiac Output Monitoring FCCNC 2018
Hajni Hideg
Practice Educator
St George’s Hospital
Cardiothoracic Intensive Care Unit

2. Learning objectives By the end of the session learners will be able to:
State the indications for invasive flow monitoring in the critically ill patient.
Define the determinants of blood pressure and describe how these factors are interpreted and optimized to support the cardiovascular system.
Name 3 equipment types used for flow monitoring.
Explain the definition of oxygen delivery, oxygen consumption, SvO2 and ScvO2.

3. How CO monitoring helps us?
The aim of haemodynamic monitoring and support is to optimise oxygen delivery and provide adequate perfusion to the tissues.
Oxygen delivery is determined by CO (flow)  need to maintain flow not just BP!
Inadequate flow leads to organ dysfunction, multiple organ failure and death Early detection of this is vital
CO monitoring allows us to assess flow of blood to the tissues, and provides information on how best to support a failing circulation.
(Alhashemi JA, et al.: Cardiac output monitoring: an integrative perspective. Critical Care 2011, 15:214.)

4. Indications/use of CO monitoring
Early detection of problems
Provision of additional information (Can measure CO,CI,SV, SVR, DO2, SVO2)
Diagnosis
To guide or limit therapeutic interventions
Check response to treatment
Deterioration, new cardiovascular instability

5. Pressure, Volume & Flow
Combination of all 3 ensure perfusion to all areas!
Blood pressure
Cardiac output or index - flow
CO = Stroke volume x HR
Determinants of Blood pressure:
BP=CO x SVR

6. Cardiac Output Cardiac Output Heart Rate Stroke Volume Preload
Afterload
Contractility

7. Approaches & Devices LiDCO (Lithium Dilution Cardiac Output)
Oesophageal Doppler
PAC (Pulmonary Artery Catheter)
There are more!

8. Lithium Dilution Cardiac Output (LIDCO)
Uses a small dose of Lithium as an indicator to directly measure CO as the device is calibrated.
PulseCo uses pulse pressure analysis of the arterial waveform to derive CO, this is adjusted for the individuals physiology when the device is calibrated
Lithium can be injected into peripheral vein via a large bore cannula or CVC

9. PulseCO Monitor Beat-to-beat changes CO/CI Mean Arterial Pressure
SVR & SVRI
Stroke Volume
Heart Rate
DO2 & DO2I

10. The PA catheter: the ‘gold standard’ ?
Dr HJ Swan & Dr W Ganz N Engl J Med (1970) 283:
Syringe (plunger withdraws only to 1.5ml)
introducer with side port (acts as a rapid infuser)
Sliding locking device
Markings designating distance from tip (each broad mark represents 10cm)
Connectors to monitor
8 French PVC yellow catheter
Lumens
Temperature sensitive wire with thermistor bead
Balloon surrounding tip-containing lumen in end

11. Where it sits?

12. PA catheter
Cont. cardiac output monitoring, measurement of SV, SVR, PVR (all values indexed)
Central/core temperature monitoring
measurement of PA pressure (can also measure RA and RV pressures during insertion)
measurement of mixed venous saturations (SvO2)
estimation of diastolic filling of left heart (normal PCWP 2-12mmHg)
Settings it is commonly used are:
RV/LV failure
pulmonary hypertension
weaning failure of cardiac origin
post-cardiac surgery

13. Normal values CO 4-8 L/min SV 60-130 ml PA Syst 15-25 mmHg
PA Diast 6-12 mmHg
PAOP 4-12 mmHg
SVR dyne/sec/cm-5
PVR
LVSW gm/beat
RVSW 8-16 gm/beat
DO mlO2/min
VO mlO2/min
CI L/min/m2
SVI ml/beat/m2
SVRI
PVRI
LVSWI 50-62
RVSWI 5-10
DO2I
VO2I
SvO %
Darovic G (2004) Handbook of Haemodynamic Monitoring Saunders (Elsevier)

14. Trans-oesophageal Doppler
The Doppler probe is passed into the oesophagus (approx 35cm from lips) The probe is rotated until the transducer faces the descending aorta and a characteristic waveform is seen. By using an ultrasound probe to visualise directional blood flow, the phase shift This, together with the cross-sectional area of the blood vessel being observed can be used to determine flow.

15. Perfusion / Oxygen Transport
A primary function of cardiopulmonary system is to provide sufficient oxygen delivery to maintain normal tissue and organ function
O2 Delivery (DO2)
The amount of O2 (ml) pumped out by the heart & available to the body per minute
Depends on: Pulmonary gas exchange, Hb levels, Binding of O2 to Hb, CO
O2 Consumption (VO2)
The total amount of O2 consumed by the body per minute
Function of: cellular demand of oxygen, adequacy of O2 delivery, ability of cell to extract O2 from blood

16. SvO2 / ScvO2?
In simple terms, it is the oxygen saturation of the blood returning to the right side of the heart.
The amount of oxygen “left” after the tissues utilize what they need
What?
SvO2 = Mixed oxygen saturation, measured in PA
ScvO2 = Central venous oxygen, measured in SVC
When?
SvO2 = used with a PA catheter
ScvO2 = use CVC

17. SvO2/ ScvO2 Rise Drop Causes: VO2 DO2 Stress Pain Fever Shivering
 PaO2
 Hb
 Cardiac output
 DO2
VO2
 PaO2
 Hb
 Cardiac output
Hypothermia
Sedation