Background: Metformin toxicity can lead to profound shock and has a high mortality rate. Supportive care and enhanced elimination are the mainstays of therapy. Intermittent hemodialysis (HD) produces a higher clearance of metformin than continuous veno-venous hemofiltration or hemodiafiltration (CVVH/HDF). Nevertheless, CVVH/HDF has been proposed as an alternative in critically ill patients with the suggestion that hypotension may limit the use of HD.
Objective: This study sought to analyze the feasibility of performing hemodialysis in patients with persistent shock from metformin toxicity.
Methods: We performed a 6-year (2012-2017) retrospective chart review of patients with metformin toxicity managed at a large academic institution with a toxicology service. We included patients with persistent shock on vasopressor support who were treated with HD. Baseline characteristics, complications from treatment, timing of dialysis, and differences between mean arterial pressures before, during, and at the end of dialysis were recorded and analyzed.
Results: Despite critical mean peak lactate (23.9 mMol/L [range 17.6-27.9]), pH (6.91 [range 6.78-7.01]), and metformin levels (range 25-58 μg/mL], 6 of 7 patients recovered. All patients required prolonged HD (mean 19 h). Upon completion of HD, hemodynamics had improved (45 mm Hg [95% confidence interval 35-55 mm Hg] vs. 80 mm Hg [95% confidence interval 74-86 mm Hg]) and vasopressor support decreased. Mortality in this patient cohort was 14.3% (1/7).
Conclusion: Intermittent HD is feasible in metformin toxicity despite persistent shock and high-dose vasopressor support. Mean arterial pressures improved during the course of HD and high blood flow rates were tolerated.
Keywords: enhanced elimination; intermittent hemodialysis; metformin; shock; vasopressors.
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