Validation of a method to predict required dialysis time for cases of methanol and ethylene glycol poisoning

Background: Traditional dialysis management of ethylene glycol and methanol poisoning includes frequent intradialytic measurements of concentrations of the involved alcohol and its metabolite. A simple formula to predict the required dialysis time in advance by using patient age, sex, weight, height, dialyzer specifications, and initial toxin level was proposed and tested by us previously in 5 cases. To reach a 5-mmol/L-or-less toxin concentration target, required hemodialysis time, in hours, would be [-V ln (5/A)/0.06k], where V is the Watson estimate of total-body water in liters, A is the initial toxin concentration in mmol/L, and k is 80% of the manufacturer-specified dialyzer urea clearance in milliliters per minute at the initial observed blood flow rate. Methods: We further assessed the accuracy of this formula by reviewing all dialyzed new patients with methanol or ethylene glycol poisoning from March 2001 to March 2004 (N = 13). Results: There were no clinically or statistically significant differences between mean predicted (8.7 ± 3.4 [SD] hours) and required (8.4 ± 3.2 hours) dialysis time. No rebound increase in toxin levels occurred. Conclusion: The proposed formula is a simple, yet accurate, method to predict dialysis time for patients with methanol and ethylene glycol toxicity, confirmed by validation on an independent data set. Only initial, 2 hours before termination of dialysis, and 1 to 2 hours postdialysis measurements of toxin levels are required to ensure adequate dialysis therapy.