Hong Kong Journal of Emergency Medicine
A case of methanol poisoning
, YC Chan
CK Chan
, FL Lau
A 29-year-old male took about 300 ml industrial alcohol in a suicidal attempt. The industrial alcohol was later confirmed to be methanol. He presented to the emergency department 10 hours post-ingestion with an anion gap metabolic acidosis and an osmol gap of 76.7 mOsm/kg. Ethanol infusion was started in the emergency department at 11 hours post-ingestion before the availability of serum methanol level. The clinical diagnosis of toxic alcohol ingestion was based on the history, arterial blood gases results and the presence of a significant osmol gap. The patient was then admitted to the intensive care unit for ethanol therapy and haemodialysis. Prompt initiation of ethanol therapy and the subsequent intensive care prevented the development of life-threatening complications of methanol poisoning in this case. (Hong Kong j.emerg.med. 2007;14:94-98) 29
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Keywords: Acidosis, alcohols, ethanol
Case report A 29-year-old male took about 300 ml industrial alcohol and a small amount of red wine in a suicidal attempt in August 2005. He was brought to the emergency department 10 hours later. On arrival, he
Correspondence to: Chan Chi Keung, MRCSEd, FHKAM(Emergency Medicine) United Christian Hospital, Accident & Emergency Department, 130 Hip Wo Street, Kwun Tong, Kowloon, Hong Kong Email:
[email protected] Lau Fei Lung, FRCP, FHKAM(Emergency Medicine) United Christian Hospital, Hong Kong Poison Information Centre, 130 Hip Wo Street, Kwun Tong, Kowloon, Hong Kong Chan Yiu Cheung, FRCSEd, FHKAM(Emergency Medicine)
was asymptomatic. The initial vital signs were: GCS 15/15, BP 126/82 mmHg, pulse rate 67/min, temperature 36.6°C, respiratory rate 16/min, and oxygen saturation of 100% on room air. The physical examination was normal and there was no visual impairment. Blood was drawn at 10 hours post-ingestion for arterial blood gases on room air. The initial results were: pH 7.28, pCO2 27 mmHg (3.6 kPa), pO2 114 mmHg (15.2 kPa), HCO 3 12.4 mmol/L, base excess -12.6 mmol/L, Na + 146.6 mmol/L, K + 4.3 mmol/L, Cl − 102 mmol/L, anion gap 36.5 mmol/L. Further laboratory tests for the anion gap metabolic acidosis were performed: urea 4.5 mmol/L, spot glucose 6.6 mmol/L, lactate 1.26 mmol/L, ethanol
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undetectable, measured serum osmolarity 381 mOsm/kg. The calculated serum osmolarity was 304.3 mmol/L, with an osmol gap of 76.7 mOsm/kg. Based on the history and laboratory findings, toxic alcohol ingestion was diagnosed and treated accordingly. The methanol level at 10 hours post-ingestion was 61.2 mmol/L (Table 1) although the result was only available at about 12 hours after admission (22 hours post-exposure).
and the metabolic acidosis was nearly completely corrected. Haemodialysis was therefore stopped, with ethanol infusion continued at a slower rate of 100 ml/hr (1.8 ml/kg/hr). Ethanol infusion was eventually stopped at 49 hours post-ingestion after confirming a low methanol level. Figure 1 shows the changes of the anion and osmol gaps, methanol and ethanol levels during the clinical course.
The patient was treated by a loading dose of 400 ml 10% ethanol (7.2 ml/kg) infusion over 30 minutes in the emergency department. It was prepared by 40 ml 100% ethanol made up to 400 ml with 5% dextrose solution. He was admitted to the intensive care unit (ICU).
The total ICU stay for this patient was 55 hours. The patient was all along asymptomatic. There was a slightly elevated amylase level of 102 IU/L (normal
