Two cases of metformin-associated lactic acidosis in post-operative period in emergency department: time to be aware-case reports

Background: Diabetic patients on metformin therapy may be vulnerable to lactic acidosis during acute illness. This is particularly true since the comorbid conditions among patients with diabetes and the frequent use of renin-angiotensin system blockers increase the risk of renal dysfunction.Case Description: We present two cases of metformin-associated lactic acidosis (MALA) occurred after abdominal surgery. A 74-year-old woman presented to emergency department (ED) for a transient loss of consciousness. She had vomiting, diarrhea, and lack of appetite in the last 3 days and she had had an abdominal adhesiolysis surgery 12 days before. A 78-year-old man, with history of right hemicolectomy performed 15 days before admission to ED. Patient presented with diffuse abdominal pain, diarrhea, nausea, and vomiting). Arterial blood gas analysis showed acidemia (pH 7.031), elevated anion gap (AG), lactate >15.5 mmol/L. Due to the patients' critical condition, vasopressor infusion and fluid resuscitation were started and an urgent continuous veno-venous hemodialysis with citrate and calcium (CVVHD-CiCa) treatment was provided. Conclusions: A promptly differential diagnosis at ED and early treatment with vital support and CVVHDCiCa enabled the resolution of MALA, which can often be a fatal complication in diabetic patients taking metformin. Close collaboration with the surgical and endocrinological team would be necessary for the management of the postoperative period planning the reintroduction of metformin in patients undergoing major abdominal surgery, to avoid the possibility of the onset of MALA.