Performance of Carbon Dioxide (CO2)-Derived Parameters in Predicting Low Cardiac Output Syndrome

In congenital cardiac intensive care, low cardiac output syndrome (LCOS) after surgery is defined by a decrease in cardiac output due to cardiac dysfunction. This syndrome is responsible for postoperative mortality and morbidity, as well as prolonged hospitalization.

carbon dioxide (CO2)-derived parameters are increasingly used to identify low cardiac output status by the venous-to-arterial carbon dioxide difference (PCO2 gap), or anaerobic metabolism by the venous-to-arterial carbon dioxide difference to arterial-to-venous oxygen content difference (Pv-aCO2/Ca-vO2) ratio, particularly in septic shock in adults, with or without hypoxemia. The thresholds proposed as pathological values were a PCO2 gap ≥ 6 mmHg and a Pv-aCO2/Ca-vO2 ratio ≥ 1.4 mmHg/ml. However, these markers have not been studied in depth in patients who have undergone cardiac surgery. In adults, studies have focused on the predictive value of the PCO2 gap and Pv-aCO2/Ca-vO2 on postoperative complications. In the pediatric population following cardiac surgery, only retrospective studies exist, with conflicting results on the correlation between the PCO2 gap and cardiac output, and the PCO2 gap and duration of mechanical ventilation.

This study aims to compare the performance of CO2-derived parameters in predicting LCOS and anaerobic metabolism in children after cardiac surgery with cardiopulmonary bypass.