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Loss of indicator in the thermodilution technique
Catheterization and Cardiovascular Diagnosis
|January 1, 1978
Summary
A second thermistor in right heart catheters can improve cardiac output accuracy. Injectate temperature variations lead to overestimations of 3-12% in cardiac output measurements.
Area of Science:
- Cardiovascular physiology
- Medical device engineering
Background:
- Standard right heart thermodilution catheters use a single thermistor.
- Accurate cardiac output measurement is crucial for patient management.
- Injectate temperature can influence thermodilution accuracy.
Purpose of the Study:
- To describe the use of a second thermistor for improved injectate temperature detection.
- To quantify the impact of injectate temperature variations on cardiac output measurements.
Main Methods:
- A standard right heart thermodilution catheter was modified with a second thermistor.
- Experiments were conducted using chilled (0°C) injectate.
- Serial injections were performed 30-60 seconds apart.
Main Results:
- Injectate temperature entering the catheter was consistently above 0°C.
- Injectate temperature varied with time and the temperature gradient.
- Successive injections showed decreasing temperatures, plateauing by the third injection.
- These factors resulted in cardiac output overestimations of 3-12%.
Conclusions:
- A second thermistor can detect injectate temperature variations.
- Injectate temperature fluctuations introduce significant overestimation in cardiac output.
- Further investigation into optimizing thermodilution techniques is warranted.