Can we obtain a noninvasive and continuous estimation of cardiac output? Comparison between three noninvasive methods

Area of Science:

• Cardiology
• Hemodynamics
• Medical Devices

Background:

• Assessing cardiac output (CO) is crucial for managing critically ill cardiac patients.
• Noninvasive methods like inert gas rebreathing (IGR) and 2D-Doppler echocardiography are validated for CO measurement.
• Estimated continuous cardiac output (esCCO) offers a novel approach using electrocardiogram, pulse oximetry, and arterial blood pressure.

Purpose of the Study:

• To evaluate the agreement and reproducibility of esCCO compared to IGR and 2D-Doppler echocardiography for noninvasive CO calculation.
• To assess the clinical utility of esCCO in critically ill cardiac patients.

Main Methods:

• A comparative study involving 34 cardiac patients.
• Simultaneous CO measurements using esCCO, IGR, and 2D-Doppler echocardiography.
• Statistical analysis using Bland and Altman plots and intraclass correlation coefficients.

Main Results:

• Good agreement observed between IGR and 2D-Doppler echocardiography (bias = 0.31 L/minute).
• esCCO showed a larger bias compared to IGR (1.18 L/minute) and 2D-Doppler echocardiography (1.51 L/minute).
• Intraclass correlation was poor across all methods, but esCCO demonstrated satisfactory reproducibility and accuracy.

Conclusions:

• esCCO exhibits satisfactory reproducibility and accuracy, comparable to established methods.
• The larger bias suggests esCCO may be more suitable for patient screening and monitoring rather than precise individual CO assessment.
• Further validation is warranted for widespread clinical adoption in critical care settings.