Microdialysis in Liver Ischemia and Reperfusion injury

Abstract: Introduction: New chemotherapy regimens and improvements in surgical technique have increased the number of patients with liver tumours eligible for curative liver resection. There is a significant risk of bleeding during liver surgery, but this risk can be reduced if the portal inflow is temporarily closed; i.e. the Pringles maneuver (PM). If the PM is used, the liver will suffer from ischemia and reperfusion injury (IRI). If the liver remnant is too small or if the patient has chronic liver disease, the IRI may inhibit the regeneration of the liver remnant. The patient may then die from postoperative liver failure. Several strategies have been tried to protect the liver from IRI. For instance can the PM be applied in short intervals or reactive oxygen species can be scavenged by antioxidants. There are no sensitive methods available for studying IRI in patients and little is known how IRI affects the metabolism in the liver. Microdialysis is a technique that allows for continuous sampling of interstitial fluid in the organ of interestAim: To investigate the effects of ischemia and reperfusion on glucose metabolism in the liver using the microdialysis technique.Method: A porcine model of segmental ischemia and reperfusion was developed. The hepatic perfusion and glucose metabolism was followed for 6-8 hours by placing microdialysis catheters in the liver parenchyma (studies I-III). In study IV, 16 patients were randomized to have 10 minutes of ischemic preconditioning prior to the liver resection, which was performed with 15 minutes of ischemia and 5 minutes of reperfusion repetitively until the tumour(s) were resected.Results: During ischemia the glucose metabolism was anaerobic in the ischemic segment, while the perfused segment had normal glucose metabolism. Urea was added in the perfusate of the microdialysis catheters and was found to be a reliable marker of liver perfusion. The antioxidant NAcetylcystein (NAC) improved the hepatic aerobic glucose metabolism in the pig during the reperfusion, shown as reduced levels of lactate and improved glycogenesis in the hepatocytes. This can be explained by the scavenging of nitric oxide by NAC as nitric oxide otherwise would inhibit mitochondrial respiration. Also IP improved aerobic glucose metabolism resulting in lower hepatic lactate levels in patients having major liver resections.Conclusion: Microdialysis can monitor the glucose metabolism both in animal experimental models and in patients during and after hepatectomy. Both NAC and IP improves aerobic glucose metabolism, which can be of value in patients with compromised liver function postoperatively.