Relation of cerebral tissue oxygenation index to central venous oxygen saturation in children

Objective: To evaluate the relationship between the cerebral tissue oxygenation index measured by near-infrared spectroscopy and central venous oxygen saturation (SvO₂) after corrective surgery of congenital heart defects in children. Design: Prospective observational clinical study. Setting: A tertiary neonatal and paediatric intensive care unit for paediatric cardiology. Patients: Neonates and children consecutively admitted to the paediatric cardiology intensive care unit after corrective surgery of non-cyanotic congenital heart defects. Measurements and results: Forty-three children were studied. Cerebral tissue oxygenation index, measured non-invasively by near-infrared spectroscopy, was compared to SvO₂, measured by a catheter placed in the right atrium, and to haemodynamic and respiratory parameters. Pearson's correlation co-efficients and p values were calculated. Simultaneously measured values for SvO₂ (62.2±9.8%, 39.8-80.4%) and cerebral tissue oxygenation index (56.7±8.8%, 35.8-71.2%) showed a significant correlation (r=0.52, p<0.001). Conclusion: Cerebral tissue oxygenation index and SvO₂ are not interchangeable parameters, but cerebral tissue oxygenation index reflects the haemodynamic influence on cerebral oxygenation after cardiovascular surgery. Further work is necessary to confirm the clinical role of continuous non-invasive measurement of cerebral tissue oxygenation index with regard to the variations of global systemic oxygen consumption after cardiac surgery in children.