Evaluation of visible diffuse reflectance spectroscopy in liver tissue: validation of tissue saturations using extracorporeal circulation

Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period. Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for measuring liver tissue saturation in vivo. Approach: A custom-built vis-DRS probe was calibrated using phantoms with hemoglobin (Hb) and polystyrene microspheres. Ex vivo (extracorporeal circulation) and in vivo protocols were used in a swine model ([Formula: see text]) with validation via blood gas analysis. Results: In vivo absorption and scattering measured by vis-DRS with and without biliverdin correction correlated closely between analyses. Lin’s concordance correlation coefficients are 0.991 for [Formula: see text] and 0.959 for [Formula: see text]. Hb measured by blood test and vis-DRS with ([Formula: see text]) and without ([Formula: see text]) biliverdin correction were compared. Vis-DRS data obtained from the ex vivo protocol plotted against the [Formula: see text] derived from blood gas analysis showed a good fit for a Hill coefficient of 1.67 and [Formula: see text] ([Formula: see text]). A conversion formula was developed to account for the systematic deviation, which resulted in a goodness-of-fit [Formula: see text] with the expected oxygen dissociation curve. Conclusions: We show that vis-DRS allows for real-time measurement of liver tissue saturation, an indicator for liver perfusion and oxygen delivery.