1. Flow Monitoring Approaches
Jane Roe
Practice Educator (Intensive Care)
Adapted by Sarah Leyland (May 2016)

2. PAC (Pulmonary Artery Catheter)
Thursday, 20 September 2018
Approaches & Devices
Oesophageal Doppler
PAC (Pulmonary Artery Catheter)
LiDCO (Lithium Dilution Cardiac Output)
SvO2(via PAC), ScvO2 (via CVP)
There are more!
Jane Roe FCCN 2008

3. 20/09/2018
Pressure, Volume & Flow
Combination of all 3 ensure perfusion to all areas
Blood pressure
Cardiac output or index - flow
Stroke volume
Preload
Afterload
Contractility
Systemic vascular resistance
Frank Starling Law
Rosie Maundrill, November 2007

4. Cardiac Output

5. DETERMINANTS OF CO Heart Rate Preload Afterload Contractility
CVP: Indicates patient‘s heart filling
SVV: Preload Responsivness (>13%) (ETT)
Afterload
SVR: Relaxation / Contraction of arteries.
Contractility
SV: Power of heart contraction

6. The PA catheter: the ‘gold standard’ ?
Thursday, 20 September 2018
The PA catheter: the ‘gold standard’ ?
Dr HJ Swan & Dr W Ganz N Engl J Med (1970) 283:
Jane Roe FCCN 2008

7. Where it sits:

8. What you see as it goes in:

9. Normal values CO 4-8 L/min SV 60-130 ml PASyst 15-25 mmHg
PADiast 6-12 mmHg
PAOP 4-12 mmHg
SVR
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 %
(Resistance measured in dyne/sec/cm-5) Darovic G (2004) Handbook of Haemodynamic Monitoring Saunders (Elsevier)

10. 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 (autocalibration)
Lithium can be injected into peripheral vein via a large bore cannula or CVC

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

12. Perfusion / Oxygen Transport
A primary function of cardiopulmonary system is to provide sufficient oxygen delivery to maintain normal tissue and organ function
O2 Delivery / availability (DO2)
The amount (ml) of O2 pumped out by the heart & available to the body per minute
O2 Consumption (VO2)
The total amount of O2 consumed by the body per minute

13. Oxygen Delivery (DO2) Consists of: Dependent on:
Thursday, 20 September 2018
Oxygen Delivery (DO2)
Consists of:
Oxygen content of arterial blood (CaO2 = SaO2 x [Hb] x 1.36) WITH
The flow of blood leaving the left side of the heart (CO)
DO2 = CO x CaO2
Normal DO2 = 900 – 1100 ml/min
Normal DO2 I= 520 – 720 ml/min/m2 (indexed value)
Dependent on:
Pulmonary gas exchange
Haemoglobin levels
Binding of O2 to haemoglobin
Cardiac Output
Oxygen delivery or oxygen availability
Jane Roe FCCN 2008

14. Oxygen Delivery to the Cells
Thursday, 20 September 2018
Oxygen Delivery to the Cells
Gas Exchange Macro Circulation Micro Circulation Cell Function
Goal: Optimal Tissue Oxygenation
Jane Roe FCCN 2008

15. Oxygen Consumption (VO2)
Consists of:
Oxygen content of arterial-to-mixed venous blood (CvO2 = SaO2 - SvO2 x [Hb] x 1.36) WITH
The flow of blood leaving the left side of the heart (CO)
VO2 = CO x CvO2
Normal VO2 = 200 – 290 ml/min
Normal VO2 I = ml/min/m2 (index value)
Function of:
The cellular demand of oxygen
Adequacy of O2 delivery (DO2)
Ability of cell to extract O2 from blood

16. ScvO2 and SvO2 What? SvO2 = Mixed oxygen saturation, measured in PA
ScvO2 = Central venous oxygen, measured in SVC
When?
SvO2 = used with a PA (Swan-Ganz) catheter
ScvO2 = use CVC

17. SvO2 Monitoring: What is it?
In simple terms, it is the oxygen saturation of the blood returning to the right side of the heart.
This reflects, in a way, the amount of oxygen “left” after the tissues remove and utilize what they need

18. ScvO2 How Do We Measure It?
Thursday, 20 September 2018
ScvO2 How Do We Measure It?
Direct measurement
Blood sample from distal lumen of CVC analyzed by a normal blood gas machine
Best if IVC for lower body
SVC e.g. via jugular) result is upper body
Does show trends
Jane Roe FCCN 2008

19. How Do We Measure It? Oximetric Swan (Pulmonary Artery Catheter)
Direct measurement
Blood sample from distal lumen of pulmonary artery catheter can be analyzed by a normal blood gas machine
Used for calibration

20. Changes in ScvO2 – Possible Clinical Correlations
Drop
Rise
Causes:
VO2
DO2
Stress
Pain
Fever
Shivering
 PaO2
 Hb
 Cardiac output
 DO2
VO2
 PaO2
 Hb
 Cardiac output
Hypothermia
Sedation

21. If your numbers don’t fit your clinical findings…
Recheck
Recalibrate
Rethink

22. Thursday, 20 September 2018
And…
Always use observations in conjunction with “whole patient” observations
Trends in observations not “one-off’s”
Baseline observations are very important
Standardised conditions
Accurate & meaningful
Appropriate use, not routine or ritualised
Understand significance of any change
Jane Roe FCCN 2008