Lidocaine metabolite formation as a measure of perioperative liver function

In order to determine whether lidocaine metabolism, as the formation of monoethylglycinexylidide (MEGX), could be used as a quantitative index of perioperative liver function, serum levels of MEGX in 31 surgical patients were measured and compared with the results of conventional liver function tests. A significant correlation was found between the values of MEGX and ICGR15 in 20 of the 31 patients. The values of ICGR15 were lower than 20% in patients whose MEGX values were above 60 ng/ml and 20% or higher in those with MEGX values of lower than 60 ng/ml. There was also a significant correlation between MEGX values and antithrombin III values, and between MEGX values and the postoperative maximum levels of aspartate aminotransferase. However, no correlation was found between MEGX values and other preoperative conventional liver function tests in any of the 31 patients. We suggest that a cut-off MEGX value of 60 ng/ml be used as an indicator for satisfactory preoperative liver function. MEGX formation could be a useful prognostic index for patients who have undergone surgical procedures for liver disease, and employed as a quantitative assessment of perioperative liver function.