Methanol outbreak in Norway 2002-2004: epidemiology, clinical features and prognostic signs

Abstract

Objectives: Knowledge on methanol poisoning does mainly come from clinical studies. We therefore report epidemiological, clinical and prognostic features from the large methanol outbreak in Norway in 2002-2004 where the new antidote fomepizole was the primary antidote in use.

Design and subjects: Combined prospective and retrospective case series study of 51 hospitalized patients who were confirmed poisoned with methanol, of whom nine died. In addition, eight patients died outside hospital. Most patients were admitted in a late stage and because of symptoms. Treatment consisted of alkali, fomepizole (71%) and haemodialysis (73%).

Results: The median serum methanol was 25.0 mmol L-1 (80 mg dL-1) (range 3.1-147.0 mmol L-1), median pH was 7.20 (6.50-7.50), and median base deficit 22 mmol L-1 (range 0-31). The most frequent clinical features reported were visual disturbances (55%), dyspnoea (41%), and gastrointestinal symptoms (43%). Twenty-four per cent were comatose on admission, of whom 67% died. There was a trend towards decreasing pCO2 with decreasing pH amongst the patients surviving. The opposite trend was demonstrated in the dying; the difference was highly significant by linear regression analyses (P<0.001).

Conclusions: Methanol poisoning still has a high morbidity and mortality, mainly because of late diagnosis and treatment. Respiratory arrest, coma and severe metabolic acidosis (pH<6.90, base deficit>28 mmol L-1) upon admission were strong predictors of poor outcome. Early admission and ability of respiratory compensation of metabolic acidosis was associated with survival.