What are the symptoms of methanol poisoning? _Industrial additives

What is methanol

Methanol, CAS number: 67-56-1, molecular formula CH3OH, also known as “wood alcohol”, “wood alcohol”, “wood alcohol” or “methyl hydroxide”, is an organic compound and also has a structure The simplest saturated monohydric alcohol. Appearance: colorless, transparent, flammable, volatile toxic liquid. The pure product has a slight smell of ethanol, while the crude product is pungent and unpleasant. Can cause blindness.

The explosion limit of the mixture of steam and air is 6~36.5% (volume ratio), and it is miscible with water, ethanol, ether, benzene, ketones, halogenated hydrocarbons and many other organic solvents. Usually used as solvent, antifreeze, fuel or neutralizer.

Symptoms of methanol poisoning

Drinking 5 to 10 ml by mistake can cause blindness, and drinking large amounts can lead to death. The main damaged organs after acute methanol poisoning are the central nervous system, optic nerve and retina.

1. Irritation symptoms: Inhaling methanol vapor can cause eye and respiratory mucosa irritation symptoms.

2. Central nervous system symptoms:Patients often experience dizziness, headache, vertigo, fatigue, staggering gait, insomnia, indifferent expression, and cloudy consciousness. Severe cases may cause confusion, coma, epileptic convulsions, etc. People with severe oral poisoning may have symptoms of extrapyramidal damage or Parkinson’s syndrome. Head CT examination revealed symmetrical infarction and necrosis of the lentiform nucleus and central subcortical white matter. Symptoms such as hallucinations and depression.

3. Eye symptoms:Initial symptoms include dark shadows in front of the eyes, flashing lights, blurred vision, eyeball pain, photophobia, diplopia, etc. In severe cases, vision drops sharply, which can lead to permanent blindness in both eyes. Examination shows dilation or constriction of pupils, slow or disappearance of light response, papilledema, peripheral retinal congestion, hemorrhage, edema, and optic nerve atrophy in the late stage.

4. Digestive system and other symptoms: Patients have nausea, vomiting, upper abdominal pain, etc., which may be complicated by liver damage. Oral poisoning may be complicated by acute pancreatitis. A few cases are accompanied by tachycardia, myocarditis, S-T segment and T wave changes, acute renal failure, etc. Severe acute methanol poisoning can cause severe headache, nausea, vomiting, sharp decline in vision, and even blindness, confusion, delirium, convulsions and coma. Eventually, death may occur due to respiratory failure.

5. Metabolic acidosis: Carbon dioxide binding capacity is reduced, in severe cases cyanosis occurs, and breathing is deep and rapid (Kussmaul breathing, also called Kussmaul breathing)

According to the history of methanol exposure, clinical manifestations mainly include central nervous system damage, eye damage and metabolic acidosis in a short period of time. Referring to the on-site hygiene investigation and excluding other diseases with similar manifestations, the diagnosis is not difficult after comprehensive analysis. If necessary, blood and urine methanol measurements can be made. In the early stage of poisoning, it should be distinguished from colds, neurasthenia, acute gastroenteritis, etc. In addition, it should be distinguished from methyl chloride, ethylene glycol acute poisoning and encephalopathy and optic nerve damage caused by other reasons. Detailed occupational history inquiries, on-site hygiene investigations, close observation of disease progression, and laboratory examinations are necessary to arrive at a correct diagnosis.

Methanol poisoning first aid treatment methods

1. The patient should move away from the scene immediately and take off contaminated clothes.

2. For oral administration, use 1% sodium bicarbonate for gastric lavage and magnesium sulfate for catharsis. Removes absorbed methanol from the body.

3. Antidote: Ethanol is the antidote for methanol poisoning. The application of ethanol can prevent the oxidation of methanol and promote the discharge of methanol. Use 10% glucose solution to prepare a 5% ethanol solution and infuse slowly intravenously. There is not much clinical experience in China.

4. Correct acidosis: Based on blood gas analysis or carbon dioxide binding capacity measurement and clinical manifestations, give sodium bicarbonate solution or sodium lactate solution as soon as possible.

5. Support and symptomatic treatment: Actively prevent and treat cerebral edema according to the condition, reduce intracranial pressure, improve fundus blood circulation, and prevent optic neuropathy. Maintain respiratory and circulatory functions and maintain electrolyte balance. Give plenty of B vitamins. It has been suggested to use formate and 4-methylpyrazole (4MP) to treat methanol poisoning, which has been confirmed in experimental studies on monkeys but has not been used clinically so far.

6. Dialysis therapy: Patients with severe poisoning should undergo hemodialysis or peritoneal dialysis as soon as possible to reduce the symptoms of poisoning, save the patient’s life and reduce sequelae. Indications for hemodialysis therapy are:

①Blood methanol>15.6mmol/L; or formic acid>4.34mmol/L;
②Severe metabolic acidosis;
③Severe visual impairment or papillretinal edema.

Methanol poisoning incubation period

The incubation period of inhalation poisoning is generally 1 to 72 hours, and sometimes 96 hours; the incubation period of oral poisoning is usually 8 to 36 hours; if ethanol is ingested at the same time, the incubation period is longer.

This article is organized by CoCo