Veno-arterial CO₂ difference and cardiac index in children after cardiac surgery

Area of Science:

• Pediatric Cardiac Surgery
• Hemodynamics
• Critical Care Medicine

Background:

• Veno-arterial CO2 difference (CO2 gap) is often used to assess low cardiac output.
• Its utility in pediatric patients post-cardiac surgery requires further investigation.

Purpose of the Study:

• To evaluate the correlation between veno-arterial CO2 difference and cardiac index (CI) in children after cardiac surgery.
• To assess the association of CO2 gap with other perfusion parameters and complex clinical outcomes.

Main Methods:

• Retrospective analysis of data from 40 pediatric patients undergoing cardiac surgery.
• 127 paired arterial and venous CO2 measurements were collected within 5 days postoperatively.
• Correlation and univariate association analyses were performed with CI, vasoactive inotropic score, systolic arterial pressure, dP/dtMAX, arterio-venous O2 difference, lactates, and complex clinical course.

Main Results:

• No significant correlation was found between veno-arterial CO2 difference and cardiac index (r: -0.16, p = 0.08).
• Significant correlations were observed between CO2 gap and vasoactive inotropic score (r: 0.21, p = 0.02), systolic arterial pressure (r: -0.43, p = 0.0001), dP/dtMAX (r: 0.26, p = 0.004), and arterio-venous O2 difference (r: 0.63, p = 0.0001).
• Veno-arterial CO2 difference was significantly associated with a complex clinical course (OR 1.13, 95% CI 1.01-1.35).

Conclusions:

• Veno-arterial CO2 difference does not reliably correlate with cardiac index in this pediatric post-cardiac surgery cohort.
• The CO2 gap can serve as an indicator of a complex clinical course, particularly when analyzed alongside other perfusion variables.