Methyl alcohol poisoning is an acute intoxication provoked by ingestion of methanol. The main symptoms are repeated vomiting, nausea, pain in the epigastric zone, psychomotor agitation, dizziness. Then the picture is replaced by lethargy, weakness, visual impairment, progressive respiratory and cardiovascular insufficiency. Pathology is diagnosed on the basis of anamnesis and toxicochemical examination of urine, blood. A specific antidote is ethyl alcohol, administered intravenously or orally.
ICD 10
T51.1 Toxic effect of methanol
General information
Methanol (methyl, wood alcohol, methyl hydrate) is a representative of the group of monatomic alcohols. It has pronounced toxic properties. Upon penetration into the blood, it is oxidized to formaldehyde, affects the nervous system and visceral structures, disrupts the acid-base balance. The use of 10 or more milliliters of pure substance leads to severe poisoning. The lethal dose is 1-2 ml of methyl hydrate per 1 kg of body weight. It is found in the composition of surrogate alcohol, adulterated non-freezing liquids for cars, and other technical substances.
Causes
Methyl alcohol poisoning mainly occurs during abstinence in people suffering from alcohol dependence. Methanol does not differ in taste and smell from food ethyl alcohol. Alcoholism patients often confuse these fluids, which causes exotoxicosis. The increase in the severity of pathology is facilitated by the fact that toxic effects do not appear immediately. Other possible causes:
- Low-quality hot drinks. There are many situations when methanol was added to adulterated alcoholic products (vodka, cognac, whiskey). This led to mass poisoning among socialized people who are not addicted to alcohol.
- The use of windscreen washers. Cheap illegal windshield wipers for cars may contain methanol. When used in normal mode, intoxication does not occur. Methyl alcohol poisoning can develop when the washer is sprayed in confined spaces or ingested.
- Accidents at work. Methyl hydrate is widely used in industry to produce formaldehyde, solvents, as an element of aviation and rocket fuel. If the tanks are destroyed, a toxicant leak and mass poisoning of the company’s employees are possible. The risk increases if an emergency occurs indoors.
Pathogenesis
Methanol is rapidly absorbed from the gastrointestinal tract, relatively evenly distributed in tissues. A slightly larger amount of it is retained in organs with a high fluid content. Metabolism proceeds according to the type of lethal synthesis with the formation of formaldehyde, formic acid. The excretion of metabolites is carried out by the kidneys. About 10% of wood alcohol is removed through the lungs in an unchanged form.
Methylhydrate has a psychotropic effect, causes a state of intoxication, deafness, sopor. The formaldehyde accumulating in the body leads to atrophy of the optic nerve, retinal damage, complete or partial loss of vision. Other effects are caused by severe decompensated metabolic acidosis, changes in the activity of neurotransmitters, hormones, and enzymatic systems.
Classification
Methyl alcohol poisoning is divided into several parameters. For statistical reporting, it is more appropriate to use classification depending on the causes of pathology (accidental, for the purpose of alcoholization, professional). In clinical practice , the division is used according to the severity and level of damage to internal structures:
- Easy. It is characterized by initial manifestations of intoxication without loss of consciousness. There is a gradual increase in the symptoms of toxic ophthalmopathy, but there is no complete loss of visual function. The clinic persists for 3-5 days, then comes a full recovery.
- Medium. Ophthalmological disorders come to the fore. They can disappear by 3-4 days, and then relapse again due to atrophy of the corresponding nerve trunks. The general condition is moderately disturbed: consciousness is preserved, toxic encephalopathy takes place.
- Heavy. There are pronounced somatic symptoms. The phenomena of gastropathy, pancreatitis, hepatitis, cerebral edema are determined. Cardiac activity and breathing are disrupted. The victim falls into a coma, an exotoxic shock occurs. Death occurs on 1-2 days from acute hemodynamic and respiratory disorders.
Symptoms
Mild methyl alcohol poisoning is accompanied by the initial appearance of intoxication, somewhat less pronounced than after taking a similar dose when using ethanol. Then comes sleep, followed by a general deterioration of well-being, nausea, abdominal pain. There are complaints about the flashing of flies in front of the eyes, double vision, blurred vision.
Moderate lesions are characterized by coordination disorders, psychomotor agitation, vomiting, headaches, unpleasant sensations in the epigastrium, the appearance of general weakness, atony. Signs of visual impairment occur after waking up, are more pronounced than with mild exotoxicosis. The symptoms may be reversible, but more often after a temporary improvement, irreversible atrophy of the optic nerve occurs.
Severe forms of methyl alcohol poisoning are accompanied by muscle pain, depression of consciousness, lack of an adequate assessment of their own condition. Breathing is disturbed, shortness of breath increases, blood pressure sometimes drops to critical figures. Meningeal symptoms, pupil dilation are determined. Clonic seizures may occur. The lesion of internal organs is moderately pronounced, multiple organ failure occurs extremely rarely.
Complications
Complications are formed mainly in the toxicogenic phase of poisoning. 10-15% of patients are diagnosed with pulmonary edema, 3-5% of patients with severe pathology develop cerebral edema, which is accompanied by multiple somatic failures. Nephropathy, hepatopathy, pneumonia, acute pancreatitis may occur. The probability of their occurrence increases in proportion to the severity of exotoxicosis.
Damage to the optic nerve occurs in 60% of victims. Of these, about 40% report a persistent decrease in vision, and another 20% — complete blindness. In most cases, these phenomena are irreversible and cannot be corrected. If the nerve has not been damaged, the ability to see is restored after 400-450 hours from the moment the toxicant enters the body. The first symptoms of ophthalmic changes appear after 18-20 hours.
Diagnostics
The exact definition of pathology is made only by the results of toxicological examination of the biological environment. At the prehospital stage, the diagnosis sounds like “intoxication with alcohol surrogates.” A toxicologist takes part in the examination of the victim. Gastroenterologist, resuscitator, ophthalmologist are involved. Differentiation is carried out with the defeat of other alcohols. The following methods are used:
- Physical. There are characteristic complaints of visual impairment, abdominal pain, vomiting. The patient confirms the fact of using low-quality alcohol. When examining severe patients, a purplish-cyanotic coloration of the collar zone is detected. Tachycardia, hemodynamic failures, shortness of breath are determined.
- Laboratory. Urine and blood contain unchanged methanol and its metabolites. There is an increase in hematocrit, blood thickening. There is a shift in pH to the acidic side, a moderate increase in the activity of liver enzymes, creatinine, urea. After the stabilization of the CSF indicators, a conclusion is made about the end of the toxicogenic stage.
- Hardware. In the early stages, with the help of ophthalmoscopy, edema of the retina and optic nerve is detected, later — narrowing of the arteries and fields of vision, pallor of the papillae. ECG shows slowing of intraventricular and atrioventricular conduction. Chest x-ray allows you to visualize signs of pulmonary edema and pneumonia (symptoms of “butterfly wings”, areas of darkening).
Treatment
Hospitalization of the victim is required. If the fact of the use of methyl hydrate was established immediately after the incident, it is necessary to immediately induce vomiting in the patient. To do this, the fingers are pressed on the root of the tongue. Next, give the patient 100-150 ml of vodka to drink and call the ambulance team. After a few hours, provocation of vomiting does not allow significant improvement to be achieved.
First aid
If no more than 2-3 hours have passed since the use of the poison, a probe gastric lavage is indicated. For this purpose, cool drinking water is used without the addition of adsorbents, since the latter are ineffective against alcohols. The total amount of washing liquid reaches 10 liters. The manipulation is completed when the remains of food and stagnant contents stop leaving the probe.
The basis of first aid is oral or intravenous administration of food alcohol. It should be understood that methanol is not neutralized in this case. There is only a temporary cessation of its metabolism, since alcohol dehydrogenase has a greater affinity for ethanol than for other compounds of this group. The victim is given to drink 100 ml of the drug in a dilution of 5% glucose. A similar mixture can be administered intravenously. This is followed by emergency hospitalization.
Inpatient treatment
The antidote therapy started on PHS continues in the hospital. Glucose-ethanol mixture is administered intravenously every 2 hours. The total duration should be 72 hours or more. All this time, the concentration of the drug in the blood of the victim is maintained at the level of 0.5-1%. The indication for stopping alcoholism is a decrease in the content of the methyl compound to a level of less than 0.1 grams / liter of blood.
Folic acid or calcium folinate is used as a specific therapy. In addition, the patient receives sedatives, non-specific antidotes, vitamins of group “B”. To accelerate the excretion of poison, forced diuresis is prescribed. The water load is created using crystalloid solutions. Severe patients require hemodialysis and resuscitation support.
Rehabilitation therapy
Poisoning with methyl alcohol requires certain restorative measures. After discharge from the hospital, the patient is observed by an ophthalmologist for timely diagnosis of optic nerve atrophy. It is necessary to observe a sparing diet, the appointment of hepatoprotectors in case of liver dysfunction. Abundant drinking is indicated, control of the daily amount of urine. Treatment of alcoholism is recommended if the victim suffers from this disease.
Prognosis and prevention
The prognosis directly depends on the severity of the chemical injury. Mild exotoxicoses usually end in complete recovery without residual pathology. Moderate cases are accompanied by partial or complete blindness with the inability to correct. Severe methyl alcohol poisoning has an unfavorable prognosis. Mortality exceeds 13%, visual disorders are diagnosed in 60% of patients.
To prevent accidental poisoning, methanol should be stored indoors. Only people who do not suffer from chronic alcoholism are allowed to work with him. Containers containing methyl hydrate are marked accordingly. It is forbidden to operate glass washers based on methyl alcohol, since prolonged inhalation of its vapors can theoretically cause symptoms of intoxication.
