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Noninvasive cardiac output: simultaneous comparison of two different methods with thermodilution
D H Wong1, K K Tremper, E A Stemmer
1Department of Anesthesiology, University of California, Irvine.
Anesthesiology
|May 1, 1990
Summary
This study compared cardiac output measurements using thermodilution, bioimpedance, and Doppler ultrasound. Thoracic bioimpedance and Doppler ultrasound showed improved agreement with thermodilution in specific patient subgroups, particularly when ventricular ejection time was considered.
Area of Science:
- Cardiovascular Physiology
- Medical Instrumentation
- Critical Care Medicine
Background:
- Accurate cardiac output (CO) monitoring is crucial in critical care.
- Thermodilution (COtd) is a standard CO measurement, but other methods like thoracic bioimpedance (CObi) and suprasternal Doppler ultrasound (COdopp) are less invasive.
- Comparing the agreement between these methods is essential for clinical application.
Purpose of the Study:
- To simultaneously measure cardiac output using COtd, CObi, and COdopp in a diverse patient population.
- To evaluate the agreement of CObi and COdopp with COtd across various clinical subgroups.
- To assess the utility of ventricular ejection time (VET) in improving the reliability of CObi and COdopp measurements.
Main Methods:
- Simultaneous measurements of COtd, CObi, and COdopp were performed in 68 patients.
- Patients were analyzed in subgroups including those on mechanical ventilation, undergoing cardiac/aortic surgery, with dysrhythmias, and with sepsis.
- Ventricular ejection time (VET) was measured and correlated with CO measurements.
Main Results:
- Overall, CObi showed moderate agreement with COtd (r=0.61), and COdopp showed similar agreement (r=0.51).
- CObi demonstrated closer agreement with COtd in mechanically ventilated patients without recent surgery and with VET difference < 40 ms (r=0.74).
- COdopp showed the closest agreement with COtd in mechanically ventilated patients without recent surgery, in sinus rhythm, and with VET difference < 40 ms (r=0.82).
Conclusions:
- Thoracic bioimpedance and suprasternal Doppler ultrasound show variable agreement with thermodilution for cardiac output measurement.
- Agreement is significantly improved in specific subgroups, particularly in mechanically ventilated patients without recent cardiac or aortic surgery.
- Ventricular ejection time measurement can aid in evaluating the reliability of bioimpedance and Doppler ultrasound cardiac output estimations.