Severe methanol intoxication: Methanol pharmacokinetics and serum osmolality

Abstract

After drinking a cocktail containing Lysol and photocopier developing fluid, seven severely intoxicated patients presented with extremely high blood methanol (MeOH) concentrations ranging from 61 to 186 mmol/L (1.94 to 5.97 g/L). Supportive measures included bicarbonate administration for profound acidosis followed by prompt hemodialysis and ethanol (EtOH) infusion. Dialysis converted the elimination kinetics of McOH from zero-order to first-order and the elimination rate constant (Kd) for each patient was determined by linear regression analysis of the concentration-time data. Simultaneous venovenous dialysis of these patients using identical procedures and equipment (Dialysis A) provided consistent Kd values from which an average Kd (Kd-A), unique to Dialysis A, was calculated. Kd-A can be used to accurately predict the duration of Dialysis A therapy required in an individual case, given the initial identification and quantitation of M90H in that patient's blood. Kd, as a measure of dialysis efficiency, is influenced by factors including equipment used, catheter placement and flow rates achieved. The most efficient dialysis regimen is desirable and can be established by selecting options that yield higher Kd results. Calculated McOH concentration (C-MeOH) was derived from the osmolar gap (Δ Osm) present in excess of that produced by EtOH. C-MeOH was a very accurate estimator of McOH concentration (paired t-test; P < .01; correlation, r = .99) when compared with the reference method of headspace gas chromatography (GC-HS). During dialysis, therapeutic EtOH and falling Me0H levels were accurately monitored using readily available laboratory tests and C-MeOH. GC-HS analysis can therefore be restricted to the initial identification and quantitation of blood McOH, after which the predictable McOH elimination can be monitored using C-MeOH.