LiDCO: Lithium Dilution Cardiac Output Measurement
Instead of a change in temperature, the change you measure is of concentration. This resembles the dye-indicator dilution method.
Why Lithium? Why not, say, Thorium?
- In small doses, lithium is non-toxic
- There is no significant first-pass loss: this satisfies the “critical boundary condition”
Advantages over Thermodilution PiCCO
- The concentration stays the same throughout the arterial circulation, and thus
- You don’t need a big central artery to sample the lithium.
- You don’t need to inject the lithium through a central vein
- The technique shows good agreement with PA catheter thermodilution measurement.
- Same as all dilution methods, you get inaccurate results if there are shunts in the heart.
- If you are already on lithium, this background lithium concentration will cause the machine to overestimate your cardiac output.
- “electrode drift” can occur if there are high doses of muscle relaxants present
- You do end up disposing of some blood each time you sample.