RESUMO
BACKGROUND: Metformin accumulation is associated with lactic acidosis and haemodynamic instability. CASE PRESENTATION: A woman in her seventies with diabetes, renal failure and hypertension presented unresponsive with severe acidosis, lactataemia, bradycardia and hypotension. After the initial survey, hypotension and bradycardia were noted before she went into cardiac arrest. After resuscitation and intubation, she was moved to the intensive care unit for dialysis and supportive care. After seven hours of dialysis, her hypotension persisted despite treatment with high levels of aminopressors. Methylene blue was given, and within hours the haemodynamic situation stabilised. She was successfully extubated the next day and has fully recovered. INTERPRETATION: Methylene blue might be a valuable adjunct to dialysis in patients with metformin accumulation and lactic acidosis where other vasopressors cannot provide adequate peripheral vascular resistance.