Methanol poisoning usually results from ingestion of contaminated alcoholic beverages. Common carrier mechanisms for methanol are gas line antifreeze, glass cleaner and windshield wiper fluid. Methanol is extremely toxic. Two teaspoonsful can be fatal to a child. Two to eight ounces can be fatal to an adult. The signs and symptoms, diagnostic studies and treatment depends on the amount of ingestion.
Methanol causes multiple symptoms. Usually symptoms are present between one to 72 hours post-ingestion. Generalized weakness, fatigue, leg cramps and convulsions may be present. Rapid, shallow breathing may be present. Range of visual complaints may start from blurred vision and may progress to blindness. Cyanotic lips and fingernails may be seen. Nausea, vomiting and abd pain are common. Headaches and dizziness may progress to a coma-like state.
Comprehensive lab study (metabolic panel) will give information about the anion and osmolar gaps. This is diagnostic information and exclusive to overdoses, no matter how subtle. A pH of less than 7.0 is not uncommon, but must be treated aggressively.
Ethanol infusion is the traditional therapy for such overdoses. Large doses of ethanol competes for the same sites as methanol, therefore causing the methanol to be excreted from the body and not metabolized.
Case in point: 15-year-old female accidently ingested minute amount (approximately 1 oz.) of windshield washer fluid that had been put into a child’s juice bottle. The color of the fluid resembled the juice that her nephew had been drinking and felt nothing wrong about drinking after him.
Mom had been having trouble with the windshield washers and was manually squirting washer fluid onto the windshield. Due to the sweet taste of the drink, did not realize that it was not juice until mother happened to see the girl drinking from the bottle.
The female was rushed to the emergency department. Immediately, the emergency doctor began an ethanol infusion. The ethanol infusion was based on weight, amount of consumption and by poison controls recommendations.
The end result in this case was positive as the events happened in a short amount of time and treatment was started immediately after ingestion.
Other treatments for methanol poisoning are similar to ethylene glycol poisoning. Primary therapeutics include gastric lavage. Secondary therapeutics include hemodialysis to remove the toxic metabolites from the blood stratm. In addition, an alcohol dehydrogenase inhbitor, fomepizole (Antizol), may be used in persons greater than 12 years of age.
References
Henderson, W. R., & Brubacher, J. (2001, October 27). Methanol and ethylene glycol poisoning: A case study and review of current literature. Retrieved October 16, 2005, from http://www.caep.ca/004.cjem-jcmu/004-00.cjem/vol-4.2002/v41-034.htm
Likosky, D., Rutchik, J. S., Talavera, F., & Galvez-Jimenez, N. (2005, March 9). Methanol. Retrieved October 16, 2005, from http://www.emedicine.com/neuro/topic27.htm
Questions;
1. As a forensic nursing student or nurse with a forensic nursing certification, how would you approach the problem of diagnosing methanol poisoning?
2. If you were in the ER when someone came in and there was suspected methanol poisoning, what could you do to confirm or disaffirm that diagnosis?
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