Central Venous to Arterial CO2 Difference and Low Cardiac Output Syndrome Related Outcomes in Children After Cardiac Surgery

Inclusion Criteria: * Children aged 0-18 years old with either congenital or acquired cardiac disease * Undergone cardiopulmonary bypass for cardiac surgery * Be admitted in PICU for post-operative care Exclusion Criteria: * Preterm infant (GA \< 37 weeks) or weight less than 2 kg * Patient who weaned off cardiopulmoanry bypass and required extracorporeal membrane oxygenator (ECMO) before leaving the operating room * Patient who required emergency cardiac operation within 24 hour after hospitalization * Patient who had significant residual left side outflow tract obstruction (e.g., coarctation of aorta, interrupted aortic arch) which defined by difference of SBP between upper and lower extremities more than 10 mmHg * Patient who had already participated in another research project * Patient who does not have both arterial line and central line catheter back from operating room * Parents or legal guardian refuse to inform consent.