Society of Photo-optical Instrumentation Engineers (SPIE)
Journal of Biomedical Optics
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 (n=15) 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 μa and 0.959 for μs'. Hb measured by blood test and vis-DRS with (R2=0.81) and without (R2=0.85) biliverdin correction were compared. Vis-DRS data obtained from the ex vivo protocol plotted against the PO2 derived from blood gas analysis showed a good fit for a Hill coefficient of 1.67 and P50=34 mmHg (R2=0.81). A conversion formula was developed to account for the systematic deviation, which resulted in a goodness-of-fit (R2=0.76) 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.
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Voulgarelis, Stylianos; Fathi, Faraneh; Stucke, Astrid G.; Daley, Kevin D.; Kim, Joohyun; Zimmerman, Michael W.; Hong, Johhny C.; Starkey, Nicholas; Allen, Kenneth P.; and Yu, Bing, "Evaluation of Visible Diffuse Reflectance Spectroscopy in Liver Tissue: Validation of Tissue Saturations Using Extracorporeal Circulation" (2021). Biomedical Engineering Faculty Research and Publications. 638.
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