[Lactic Acidosis after Cardiac Surgery Treated by Continuous Renal Replacement Therapy in a Patient on Metformin;Report of a Case].

Lactic acidosis is a common condition observed in a patient after cardiac surgery. It is important to identify the pathogenesis of lactic acidosis since the delay of an appropriate treatment leads to high mortality. Metformin overdose has been known as a risk of lactic acidosis, and previous reports have demonstrated that continuous renal replacement therapy(CRRT) is effective. However, it has yet to be known if metformin-related lactic acidosis after cardiac surgery is treatable with CRRT. We, herein, report a case of 64-year-old diabetic male who had been on metformin treatment until 1 day before surgery. He presented lactic acidosis postoperatively and was successfully treated with CRRT. This case suggests that it is necessary to discontinue metformin no later than 2 days before surgery and that CRRT is of use for perioperative lactic acidosis in a patient on metformin.