Pressure (BP) is easy to measure / Flow (CO) is tricky to measure!
Cardiac output more meaningful reflection of tissue perfusion and may be better predictor of mortality and morbidity.
Pulmonary artery catheter (Gold standard)
- Useful in undifferentiated shock
- High complication rate
- Difficult to use
- 10-20% error
Calibrated e.g. PiCCO
Uncalibrated e.g. FloTrac
- Use pulse contour analysis
- Require arterial line
- Area under curve proportional to stroke volume
- 40% error
Numerous technologies in clinical use e.g. Finepress
- Low risk of complications
- >40% error