A simple method to estimate the required dialysis time for cases of alcohol poisoning

Background. Conventional dialysis management of ethylene glycol and methano l poisoning includes frequent intradialytic determinations of serum toxin c oncentration. Dialysis is continued until a target toxin concentration is r eached. Initially, the required dialysis duration is unknown, making planni ng difficult. We devised a simple method to estimate the duration of dialys is required and avoid quantitation of multiple toxin samples. Methods. Using the assumption that toxic alcohols would have a dialysis cle arance similar to urea, we proposed that required dialysis time (hours) to reach a 5 mmol/L toxin concentration target would be: [-V ln(5/A)]/0.06k, w here V (liters) is the Watson estimate of total body water, A is the initia l toxin concentration (mmol/L), and k is 80% of the manufacturer-specified dialyzer urea clearance (mL/min) at the initial observed blood flow rate. D irectly measured dialysis and renal toxin clearance, and true dialysis requ irement by conventional treatment protocol were compared with our estimate in two methanol and three ethylene glycol poisonings treated with Fresenius F8 dialyzers. Results. There were no clinically or statistically significant differences between predicted dialysis duration (7.6 +/- 1.9 hours, SD) and that actual ly provided using hourly toxin concentration sampling (7.4 +/- 1.9 hours). Renal toxin clearance was negligible compared to that of dialysis, and pred icted dialysis clearance did not differ significantly from that observed. Conclusions. The simple estimate method is sufficiently valid to guide the prescription of dialysis for toxic alcohol poisoning. Data required at dial ysis start include only the initial toxin concentration, dialyzer manufactu rer's specified urea clearance at initial observed blood pump speed, and pa tient demographics to estimate total body water. This approach allows for p lanned dialysis therapy, without the need for additional toxin concentratio n measurements until dialysis is completed.