Changes in tissue oxygenation of the porcine liver measured by near- infrared spectroscopy

Abstract

Near-infrared spectroscopy (NIRS) is a novel method for the measurement of tissue oxygenation and may have a role in monitoring liver oxygenation and viability. The aim of this study is to validate the application of NIRS for monitoring hepatic tissue oxygenation. Large Landrace pigs (n = 12) underwent laparotomy and liver exposure. Total hepatic blood flow (THBF) was measured by the Transonic Medical Flowmeter system. NIRS probes were placed on the liver surface to continuously record changes in hepatic tissue oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and the reduction-oxidation state of cytochrome oxidase (Cyt Ox). Reduction of hepatic tissue oxygenation was achieved by hepatic vascular inflow occlusion (n = 6) or reduction of inspired oxygen (FlO2; n = 6). The THBF changes correlated significantly with hepatic HbO2 (r= 0.84; P < .001) and Cyt Ox (r = 0.88; P < .001). With reduction of FlO2, a significant correlation was found between arterial oxygen saturation and hepatic HbO2 and Hb (r= 0.99 and r =-0.99, respectively; P < .0001). NIRS measurement of liver parenchymal oxygenation correlates well with changes in liver blood flow and arterial oxygenation.