Evidence for free radical-mediated lipid peroxidation at reperfusion of human orthotopic liver transplants.

Background: Generation of toxic oxygen metabolites at reperfusion may contribute to the injury sustained as a consequence of harvest and ischemic preservation of organ allografts. Because there is a paucity of evidence that this mechanism is operative in human beings, we measured the generation of ethane into the exhaled breath as a biomarker of free radical-mediated lipid peroxidation in human liver transplantation.
Methods: A novel technique that increased the previous standard of sensitivity 100-fold was used to measure picomole quantities of ethane in exhaled breath of eight recipients undergoing human orthotopic liver transplantation.
Results: Ethane production correlated closely with the specific events of liver transplantation including the initial reperfusion of the allografts. In every case a twofold to threefold increase in ethane production was superimposed on a stable baseline immediately after reestablishment of portal vein blood flow through the donor liver.
Conclusions: Ethane production was interpreted as evidence of hepatic lipid peroxidation, presumably mediated by toxic metabolites of oxygen occurring at reperfusion. This noninvasive approach allowed localization of the time point at which lipid peroxidation occurred and may facilitate quantification of lipid peroxidation mediated by free radicals and other toxic oxygen metabolites during operation.