Cardiac output assessment using oxygen consumption estimated from the left ventricular pressure-volume area

Area of Science:

• Cardiovascular Physiology
• Hemodynamics
• Medical Diagnostics

Background:

• Traditional Fick principle methods for cardiac output (CO) estimation rely on structural variables (age, sex, height) that do not fully capture physiological variations.
• These limitations can lead to inaccuracies in oxygen consumption estimation, impacting the reliability of CO calculations.

Purpose of the Study:

• To develop and validate an improved method for estimating oxygen consumption for cardiac output calculation.
• To assess the efficacy of using the left ventricular pressure-volume area (PVA) concept for this purpose.

Main Methods:

• A pilot study involving 10 patients undergoing right cardiac catheterization was conducted.
• Oxygen consumption was estimated using a formula derived from the left ventricular pressure-volume area.
• The end-diastolic-volume component of the PVA formula was varied using body weight and body surface area (BSA) for comparison.

Main Results:

• The initial PVA-based estimation of CO showed a moderate correlation (r=0.73) with thermodilution-measured CO.
• Substituting end-diastolic-volume with BSA in the PVA formula significantly improved the correlation with thermodilution (r=0.93, slope=1, ordinate=0.01).
• This suggests BSA is a superior variable for this estimation method.

Conclusions:

• The pressure-volume area concept provides a promising alternative for estimating oxygen consumption in cardiac output calculations.
• Utilizing body surface area within the PVA formula enhances accuracy compared to traditional methods and body weight adjustments.
• Further research is warranted to validate these preliminary findings in larger patient cohorts.