Liver tissue oxygenation as measured by near-infrared spectroscopy in the critically ill child in correlation with central venous oxygen saturation

Abstract

Objective: To evaluate the clinical usefulness of near-infrared spatially resolved spectroscopic quantitative assessment of liver tissue oxygenation for simple, non-invasive estimation of global tissue oxygenation in critically ill neonates and children. Design: Prospective observational clinical study. Setting: A tertiary multidisciplinary neonatal and paediatric intensive care unit (23 beds). Patients: One hundred neonates and children consecutively admitted to the paediatric intensive care unit. Measurements and results: Near-infrared spectroscopic single-point assessment of liver tissue oxygenation index (TOI_Liver) was compared with global tissue oxygenation as measured by central venous oxygen saturation (SvO₂) and derived haemodynamic parameters. Data were compared using linear and multiple regression analysis. Overall correlation between TOI_Liver and SvO₂ was good (r=0.72, p<0.0001). Multivariable regression revealed that SvO₂ alone explained 51% of the observed variance of TOI_Liver. However, our data demonstrated large inter-individual differences between SvO₂ and TOI_Liver values. Conclusion: Near-infrared spatially resolved spectroscopic quantitative measurement of liver tissue oxygenation correlates well with SvO₂ in critically ill neonates and children. Large inter-individual SvO₂ to TOI_Liver differences may prevent its use for non-invasive single-point estimation of global tissue oxygenation. Further clinical studies are required to validate the method with other regional and global haemodynamic parameters and to evaluate its clinical use for continuous non-invasive haemodynamic monitoring.