Assessment of hepatic ischaemia reperfusion injury by measuring intracellular tissue oxygenation using near infrared spectroscopy

Aims/Background: Hepatic ischaemia/reperfusion (I/R) injury is a major caus e of liver damage during liver surgery and transplantation. The relationshi p between the severity of I/R injury and the degree of intracellular hypoxi a has not been investigated. Methods: New Zealand white rabbits were used i n 4 groups (n=6 each). At laparotomy, left lobe hepatic ischaemia was produ ced for 30, 45, or 60 min followed by 60 min reperfusion and compared with controls. Liver function, bile flow, and flow in the hepatic microcirculati on (HM) were measured. Near infrared spectroscopy (NIRS) was used to monito r hepatic oxyhaemoglobin (HbO(2)), deoxyhaemoglobin (Hb), and cytochrome ox idase (Cyt Ox). Results: I/R injury produced deranged liver function tests, reduced bile flow, and reduced flow in the microcirculation in comparison with controls. During ischaemia, HbO(2) and Cyt Ox were significantly reduc ed in comparison with controls. After reperfusion, a biphasic change in tis sue oxygenation was observed, with an initial increase in HbO(2) and Cyt Ox followed by a progressive reduction. The reduction in tissue oxygenation w ith ischaemia and reperfusion paralleled the ischaemia time. After I/R, the changes in Cyt Ox (intracellular oxygenation) significantly correlated wit h the parameters of hepatocellular injury to a higher degree than HbO(2) (e xtracellular oxygenation). Conclusion: This study shows the potential of mo nitoring the degree of IIR injury by measuring hepatic tissue intracellular oxygenation.