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Comparison between ultrasonic and thermodilution cardiac output measurements in intensive care patients
Insights
Ultrasonic cardiac output measurement using continuous wave (CW) Doppler is accurate in a limited percentage of ICU patients. Combining CW Doppler with B-mode echocardiography enhances applicability when A-mode measurements fail.
Area of Science:
- Cardiology
- Medical Imaging
- Critical Care Medicine
Background:
- Cardiac output (CO) monitoring is crucial in intensive care units (ICUs).
- Thermodilution (TD) is a common CO measurement method.
- Non-invasive methods for CO assessment are desirable.
Purpose of the Study:
- To assess the reliability and accuracy of a commercial ultrasonic cardiac output measurement device.
- To compare ultrasonic CO measurement with thermodilution (TD) in ICU patients.
Main Methods:
- A commercial device combining A-mode aortic root diameter and continuous wave (CW) Doppler was used.
- CO measurements were compared between the ultrasonic method and TD in 41 ICU patients.
Main Results:
- Aortic root diameter measurement was not possible in 10% of patients.
- Acceptable CW Doppler flow signals were not obtained in 22% of patients.
- Ultrasonic CO measurement was successful in 68% of patients, showing excellent correlation with TD (r = 0.97, p < .001).
Conclusions:
- Transcutaneous CW Doppler for CO measurement is accurate and reliable in a subset of ICU patients.
- Combining CW Doppler with B-mode echocardiography improves applicability when A-mode measurements are not feasible.
Abstract:
The reliability of ultrasonic cardiac output measurement was assessed using a commercial device that combines A-mode aortic root diameter determination and continuous wave (CW) Doppler flow velocity measurement in the ascending aorta. We compared this method with thermodilution (TD) cardiac output in 41 intensive care patients. Aortic root diameter measurement with A-mode was not possible in four (10%) patients. Using strictly defined criteria based upon our initial experience, we could not obtain acceptable CW Doppler flow signals in nine (22%) patients. Thus, ultrasonic cardiac output measurement was possible in 28 (68%) patients in whom there was an excellent correlation with cardiac output (r = 0.97; p less than .001). This study demonstrates that the transcutaneous CW Doppler method for measuring cardiac output is accurate and reliable in a limited percentage of ICU patients. Combining the CW Doppler with B-mode echocardiogram increases the applicability when an A-mode measurement is not possible.