In Reply:-We appreciate the interest and comments of our colleagues regarding our case report and would like to thank the editorial board for the opportunity to respond.
We agree with Lustik et al. that a patient's diabetes mellitus should be under good control perioperatively. Therefore we would not stop metformin administration without starting an alternative therapy if appropriate.
Nevertheless, we are much more concerned about perioperative metformin medication than Lustik et al. are. The patient mentioned in our case report was treated according to the recommendations suggested by Lustik et al. He presented no contraindications for metformin (except low caloric input) until he developed severe lactic acidosis. Therefore stopping metformin could prevent a rare, but significant, risk for the patient, whereas the potential benefits of continuing the drug are rather vague.
According to the new manufacturer's recommendations in Germany, metformin should be omitted 2 days before and after general anesthesia. The risk to develop perioperative problems that would represent a contraindication for metformin medication (insufficiency of cardiovascular, pulmonary, or renal function; infections; catabolic metabolism) does not differ significantly if operations of the same size are performed in regional anesthesia. In case of ambulatory surgery we have concerns, and the development of contraindications might proceed unnoticed.
Although we agree with Lustik et al. regarding the importance of good diabetic control, we prefer to continue our rather restrictive practice of perioperative metformin therapy.
Sodium dichloroacetate (DCA), as proposed by Preiser and Vincent, could be an interesting future option for the therapy of lactic acidosis, especially because it could provide more than just symptomatic therapy.
However, DCA does not belong to the standard therapy of biguanide-induced lactic acidosis. Further, the clinical trials Preiser and Vincent refer to do not suggest DCA to be a magic bullet. Because metformin-induced lactic acidosis is a rare phenomenon and our personal experience is limited, we did not consider a therapy besides the recommended standards in this case.
Hinnerk Wulf, M.D.
Stephanie Mercker, M.D.
Christoph Maier, M.D.
Gunther Neumann, M.D.
Klinik fur Anasthesiologie und Operative Intensivmedizin der Chr.-Albrechts-Universitat Kiel; Schwanenweg 21; D-24105 Kiel; Germany;email@example.com-Kiel.de