Changes in hepatic venous oxygen saturation in hepatic warm ischemia/reperfusion injury in pigs

To clarify the changes that occur in hepatic venous oxygen saturation (ShVO2) during hepatic ischemia/reperfusion (I/R) injury, we examined the relationship between ShVO2, hepatic tissue blood flow (HTBF), and portal vein pressure (PVP) in a warm I/R model using pig livers. Female pigs weighing 18-23 kg were subjected to warm I/R under extracorporeal circulation between the superior mesentric vein and the left jugular vein to avoid portal congestion. The warm ischemic times were 120 min (n = 4), 180 min (n = 14), and 240 min (n = 4). ShVO2, HTBF, and PVP were measured after reperfusion. The survival rates of the pigs 3 days after reperfusion were 100% in the 120-min group, 57% in the 180-min group, and 25% in the 240-min group. In the 180-min group, the ShVO2 was lower in the pigs that died than in those that survived. There was a significant correlation between ShVO2 and both PVP and HTBF after reperfusion. Histological examination revealed findings of severe I/R injury in pigs with a low ShVO2, and mild I/R injury in pigs with a stable ShVO2. These observations suggest that the changes in ShVO2 could reflect the degree of hepatic I/R injury, especially that related to microcirculatory disturbances occurring at the sinusoid levels.