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Abstract: TH-PO178

Survival After Severe Metformin-Associated Lactic Acidosis (MALA) with Aggressive Dialysis and Massive Bicarbonate Administration

Session Information

Category: Trainee Case Report

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Agarwal, Neil Kumar, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Plotskaya, Natalia, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
  • Goldman, Jesse M., Drexel University College of Medicine, Philadelphia, Pennsylvania, United States
Introduction

MALA is a severe condition affecting fewer than 1 in 10,000 people. Mortality is often above 20%. We present a case of intentional metformin overdose surviving after combined dialysis modality use and massive parenteral sodium bicarbonate (NaHCO3) administration.

Case Description

52-year-old male with PMH: HIV on HAART, DM, HTN, Hep C and cocaine use who intentionally ingested 60g Metformin in the ED without staff knowledge. 12 hours later, patient was found lethargic with a blood glucose of <10 mg/dl. Arterial blood gas: pH 7.02, PaCO2 23.3mmHg, PaO2 128mmHg. Serum chemistry: Na 144mmol/L, K 3.8mmol/L, Cl 98mmol/L, Cr 1.57mg/dL, HCO3 12mmol/L, ALT 64unit/L, AST 74unit/L, AG 32, lactic acid >25.0 mmol/L. Patient was intubated, hyperventilated and begun on 3 vasopressors for hypotension. No GI lavage performed. Next, simultaneously started 150meq NaHCO3 infusion at 150mL/hr and intermittent HD (IHD) for 3 hours with O200, Qb 400mL/min and Qd 800mL/min, Bicarb bath: 40meq/L. He was transitioned directly onto CVVHD using Prismasate 4/2.5 with Qb 300mL/min and Qd 3L/hr, later increased to 5L/hr. The NaHCO3 infusion was increased to 600mL/hr due to persistent pH <7.2. An additional 50meq of NaHCO3 was added to each dialysate bag. The patient’s pH remained <7.2 throughout renal replacement therapy (RRT). A Metformin level prior to any RRT was 67mcg/dL. 11.5 hours after IHD and CVVHD initiation, the Metformin level fell to 23mcg/dL. CVVHD was continued due to anuria and high fluid requirements. 24 hours after initiating RRT, pH and HCO3 improved to 7.35 and 23mmol/L, respectively. Serum lactic acid fell from >25mmol/L to 13.7mmol/L. The patient was extubated, weaned off vasopressors and discharged after delayed renal recovery on hospital day 25 with Cr 3.41mg/dl.

Discussion

Metformin (molecular weight 129, minimal protein binding) is rapidly distributed into tissue compartments. The large volume of distribution (300-1000L) prevents complete clearance by conventional IHD resulting in prolonged toxicity. In our case, 11,780meq of NaHCO3 was given IV over 24-hours. He also received additional NaHCO3 from 3 hrs of IHD in a 40meq/L dialysate bath followed by CVVHD using 32meq/L bags, later increased to 42meq/L. High UF rate with RRT allowed massive delivery of IV NaHCO3 in combo with dialysis for aggressive treatment of MALA.