Cardiac output quantification by Doppler echocardiography in intensive care--limitations and validation

Area of Science:

• Cardiology
• Medical Imaging
• Hemodynamics

Background:

• Cardiac output (CO) quantification is crucial for managing heart failure patients on tailored therapy and invasive hemodynamic monitoring.
• Noninvasive CO assessment using Doppler echocardiography (echo-Doppler) has shown controversial concordance with invasive methods in paired measurements.
• Limited research exists on the clinical relevance of echo-Doppler for serial CO evaluation in patients undergoing tailored therapy.

Purpose of the Study:

• To assess the utility of echo-Doppler for CO evaluation and change quantification compared to thermodilution.
• To compare echo-Doppler and thermodilution in advanced heart failure patients under hemodynamic monitoring for tailored therapy guidance.

Main Methods:

• Simultaneous CO determination using echo-Doppler (dpCO) and thermodilution (tdCO) in 20 advanced heart failure patients (NYHA IV).
• Three serial CO measurements (60 total) were performed in an intensive care unit (ICU) setting.
• A difference >20% between tdCO and dpCO was defined as a major error.

Main Results:

• Echo-Doppler systematically overestimated thermodilution (p = 0.026), with a correlation of 0.81 and 19 major errors (32%).
• No significant difference was found in CO percentual variations between methods (r = 0.92, p = 0.014).
• Correcting subsequent dpCO using the initial dpCO/tdCO ratio significantly improved concordance (r = 0.96, p = 0.0002) with no errors.

Conclusions:

• Echo-Doppler shows good correlation but weak paired concordance with thermodilution for CO in advanced heart failure.
• Serial CO change assessment and corrected dpCO values suggest echo-Doppler's validity for clinical use.
• Echo-Doppler may allow for reduced invasive hemodynamic monitoring duration.