Methanol poisoning (Methanol poisoning)

Methyl alcohol (methanol, wood alcohol, carbon) is a strong biological poison and the cause of individual and mass cases of poisoning with a high percentage of deaths. Psychiatrist-narcologist Vladislav Sipovich, Chief Physician of the Multidisciplinary Medical Center, informs readers about the symptoms of methyl alcohol poisoning, first aid methods, treatment, prevention and consequences.

Definition

· Methanol (CH3OH) is a methyl monohydric alcohol, easily soluble in most liquids.
It looks no different from ethyl alcohol. · Poisoning occurs due to ingestion or inhalation of methanol (wood alcohol) vapor in quantities that cause intoxication.

· Poisoning often occurs by mistake due to use instead of ethanol or during suicide attempts.

· This is the most common type of alcohol intoxication after ethanol, with a high mortality rate.

· Can be successfully treated with an antidote, but in high doses and in the absence of medical attention it is fatal.

· CH3OH is found in propellants for cars and aircraft, and is also used in perfumes.

· Easily absorbed through the skin, by inhalation and through the intestines.

Causes of intoxication with alcohol surrogates

The main cause of poisoning with alcohol surrogates is their constant use. Some are so toxic that a single exposure to the body is enough to cause serious health problems, and if the permissible dose is exceeded, death. There are various factors that contribute to trying non-intended liquids. These are alcohol and drug addiction, bad company, family problems, bad heredity and others. Particular attention should be paid to children who may succumb to one of these factors.

Etiology and pathogenesis

Pathophysiology

· It is broken down by alcohol dehydrogenase in the liver to formaldehyde and further to formic acid, which is a harmful metabolite.

· Decomposition is slow, about twice as long as ethanol, but faster than formic acid.

· Consequently, it takes 15-20 hours for sufficient formic acid to accumulate to cause hyperventilation (compensation for acidosis) and visual impairment.

Combination of ethanol and methanol

· Both alcohols compete for the same decomposition enzyme, but ethanol has a higher affinity.

· Thus, simultaneous consumption of ethanol will have a positive effect due to the delayed formation of formic acid.

Toxicity

· The most vulnerable structures are the optic nerve and putamen (basal ganglia).

· Consumption of a critical dose causes optic atrophy and/or Parkinson's symptoms, respectively.

· The lethal dose of wood alcohol is up to 1 ml/kg, but this will depend on whether ethanol is taken at the same time.

· If CH3OH is not decomposed, it is excreted unchanged in urine and exhaled air with a half-life of up to 40 hours.

· Folic acid deficiency results in inhibited formic acid degradation.

Diagnostics

Diagnostic criteria

· The main sign of poisoning is metabolic acidosis with increased values ​​of osmolality gap and anion gap.

· Symptoms appear late, no earlier than after 15-20 hours, hyperventilation and visual disturbances appear.

· If there is combined consumption of wood alcohol and ethanol, it may take several days after ingestion before feeling unwell.

· Other symptoms include nausea, vomiting and headache.

· In the most severe cases, blindness, coma and respiratory arrest occur.

History taking

What questions should you ask the patient:

1. Amount and concentration of the substance used?
2. Time aspect?
3. Did the patient influence consumption by inducing vomiting or using sorbents?
4. Was the person taking other pills or medications? What and how much?
5. Could others ingest the same alcohol and accidentally become poisoned?
6. Does the patient have chronic problems with alcohol ? Alcoholics can tolerate more methanol before poisoning.

It is worth considering that poisoning can also occur in industrial companies through absorption through the skin or inhalation.

Clinical data

· Various degrees of decreased consciousness.

· Hyperventilation. As a rule, it is first observed in the later stages.

· Possibly fluctuating abdominal pressure.

· Coma, cyanosis.

· Ophthalmoscopy: poor reaction of the pupil to light, retinal hyperemia with inflammation.

· Blurred edges of the papilla without protrusion, the so-called pseudo papillitis.

Additional Research

· Acid status/base.

· Metabolic acidosis.

· Electrolytes.

· Glucose.

· Urea.

· Serum amylase and possibly serum lipase for the development of pancreatitis.

· Determination of methanol in blood and urine.

· In cases of severe poisoning, a CT scan of the brain (possibly an MRI) may be indicated in later stages.

· Calculation of osmolal and anion gap. It has proven to be a reliable and very good diagnostic tool for methanol poisoning.

By calculating the osmolality gap and the anion gap, a diagnosis of methanol or ethylene glycol poisoning can be made with a high probability. The treatment is the same for both. Osmolality gap and anion gap are increased in methanol poisoning.

1. Early in the process, before methanol degradation has begun, the patient will have a high osmolality gap (lots of methanol) and usually anion gap (some formic acid) and slight acidosis. Such patients are usually not severe.

2. At the end of the process, when all the monohydric alcohol is decomposed, the value for the osmolality gap will be normal, while for the anion gap it will be high (lots of formic acid). These patients are often severe.

Impact on the body

The influence of surrogates on the body has primary and secondary characteristics.

all starts with arousing the body on an emotional and physical level. The eyes begin to shine and activity increases. It seems that all problems have been solved, and the attitude towards the world around us is improving. At the same time, a person’s confidence in himself and his beliefs grows, he becomes sharp and categorical. If you start arguing with him, you will notice dilated pupils and redness of the face, which are also primary effects.

Some secondary signs cannot be noticed - this is the absorption of toxins into the blood, as a result of which the functioning of the central nervous system and brain is disrupted. Stronger alcohol intoxication occurs and the person clearly expresses the state: stupidity in judgment, aggressive behavior, sexual craving and others.

As the amount of toxins the body receives increases It becomes difficult to breathe, blood vessels narrow, speech and movements become inappropriate. This condition is characterized by crawling . With increasing intoxication, a person stops responding to everything and an alcoholic coma , which in turn can lead to death.

There are the following stages of coma:

1. The first is superficial . In order to bring a person to his senses, it is necessary to rinse the stomach.
2. The second is of medium severity. The main symptom is relaxed muscle tone. Gastric lavage will not revive the victim; hospitalization is required.
3. The third is a deep coma. There are no reflexes, no reaction to light, and convulsions may occur. Urgent medical attention is required.

A coma is most likely to occur if a person who rarely drinks alcohol takes a large dose of pure alcohol at a time.

If assistance is not provided in a timely manner, a critical condition , which will develop into death.

Therapy for methanol poisoning

Methanol poisoning is a dangerous condition that requires prompt diagnosis and treatment. The primary goal of therapy is to minimize the effect of alcohol on the body.

Generally about treatment

Treatment should begin even before a final diagnosis is made.

· Gastric lavage. It is indicated if <2 hours have passed since administration.

· Correction of acidosis. It is performed with sodium bicarbonate and is initially most important along with supporting vital functions such as breathing and circulation.

· Inhibition of alcohol dehydrogenase with ethanol or the antidote fomepizole.

· Removal of methanol and formic acid by hemodialysis. This is most often done in parallel.

Antidote for methanol poisoning

At the moment, there are 2 known antidotes for wood alcohol intoxication - ethanol and fomepizole.

Ethanol

The most accessible of the antidotes, but it has both advantages and some disadvantages for use.

Benefits of ethanol treatment:

· Low price.

· Easy access.

· Good and fast effect.

Quantity:

· The effect of ethanol on methanol degradation depends on the molar concentration between them. A lot of methanol requires a lot of ethanol and vice versa.

· For practical reasons, a therapeutic ethanol concentration of 1 g/L (22 mmol/L) is usually recommended.

Minuses:

· It has been found difficult to maintain adequate ethanol concentrations in patients, especially during concurrent dialysis. There are simple formulas for determining the amount of ethanol in various situations, and ethanol can also be added to the dialysate fluid.

· Other disadvantages of ethanol treatment are that it becomes increasingly difficult for the patient to cope with it.

· In some cases, the ethanol supply may be what makes the patient a respiratory candidate.

Treatment regimen:

1. If methanol > 0.2 g/L or acidosis, ethanol is given as a 10% solution, such as 50 mg/ml glucose solution (remove 50 ml from the 500 ml infusion bag and replace with 50 ml ethanol).

2. Start with a dose of 0.6 g/kg body weight (i.e. 1 ml 70% sterile alcohol/kg) over 15-20 minutes. For adults, an additional 7-10 g/h is given as an infusion.

Titers are such that plasma concentrations of about 1 are maintained for at least 48 hours or methanol can no longer be detected in the blood.

Fomepizole (4-methylpyrazole)

It is an effective alcohol dehydrogenase inhibitor without the side effects of ethanol and dosage problems. Inhibits the formation of toxic metabolites.

· The drug is used to treat poisoning with methanol and ethylene glycol.

· Treatment can be carried out without measuring serum values ​​even during dialysis.

Fomepizole also inhibits ethanol degradation. Therefore, any supply of ethanol should be stopped when switching to fomepizole.

Advantages:

· Ensures safe dosing.

· More effective than alcohol.

· Gives few side effects.

Flaws:

· High price.

When combined with hemodialysis, the need for intensive care is significantly less, and some patients are discharged after 24 hours.

Dosage:

· The dose is diluted in 100 ml of NaCl 154 mmol/l or glucose 50 mg/ml and administered as a slow i.v. infuse for 30 minutes.

· Initial dose of 15 mg/kg followed by doses of 10 mg/kg every 12 hours 4 times.

· Later 15 mg/kg every 12 hours.

· Can also be given orally and the dosage remains the same.

· Second dose for dialysis.

Treatment

First aid involves prompt gastric lavage. You may also need to give sodium sulfate by tube. If a patient is poisoned with methyl alcohol, he is given an antidote intravenously - an ethanol solution. If ethylene glycol poisoning is detected, the patient will require intravenous administration of sodium bicarbonate solution.

After first aid is provided, current condition is diagnosed . Thanks to this, it is possible to diagnose existing disorders and prescribe effective treatment. This may include detoxification, taking vitamins, etc.

In case of intoxication with alcohol surrogates that contain methyl alcohol, it may be necessary to take prednisolone, adenosine triphosphoric acid and atropine. These medications are used to correct visual disturbances. A spinal tap may also be performed to correct problems with the visual system.

Intoxication with ethylene glycol forces one to direct all efforts to prevent the damaging effects on the kidneys . In this case, patients are provided with assistance in the form of magnesium sulfate, drinking plenty of fluids and diuretics. This therapeutic course allows you to adjust water-salt metabolism. In especially severe cases, it is possible to prescribe extrarenal blood purification and peritoneal dialysis.

The prognosis when diagnosing “intoxication with alcohol surrogates” largely depends on the volume and type of alcohol-containing liquid consumed. In some cases, almost immediate death is possible. In this case, surviving patients will almost certainly remain disabled .

Progress, complications and prognosis

To prevent household accidents, ensure that liquids containing methanol are kept out of the reach of children and label bottles to avoid confusion between methanol and ethanol.

Gradient

· Most often the latency is 12-24 hours before symptoms appear.

· Concomitant use of ethanol will further increase latency.

· In cases of severe poisoning, severe symptoms may occur earlier.

· The course of the patient's symptoms will often be as follows: first, mild intoxication, therefore headache, lethargy and nausea, gradually visual disturbances, diffuse abdominal pain and shortness of breath are possible.

Complications

· Decreased vision or blindness.

· Parkinsonism.

· Pancreatitis, in the worst case hemorrhagic pancreatitis.

· Seizures, cerebral edema and possibly necrosis of the basal ganglia.

· Rhabdomyolysis and acute renal failure.

· Hypoglycemia.

Forecast

1. The degree of acidosis is critical to the outcome. Without treatment, methanol poisoning leads to permanent vision damage, collapse and coma.

2. Injuries to the basal ganglia may produce a Parkinson's-like picture.

3. The dose of lethal is most often indicated at 1 g/kg body weight (30-240 ml).

4. The minimum dose that can cause visual damage is unknown.

Early and proper treatment of methanol poisoning will help prevent complications.

Additional Information

Find out:

1. What substances available for everyday use contain ethylene glycol, and what properties does it have? What does ethylene glycol poisoning , what symptoms does it cause and how effectively is it treated. What antidote exists for intoxication and how accessible is it for use?
2. What are the common sources of fluoride poisoning and why are children at risk? What symptoms indicate intoxication, and what needs to be done at home to provide first aid if you feel unwell.
3. After consuming what foods can histamine poisoning , and how dangerous this condition is.
4. Due to an overdose of which drugs iron poisoning and how effectively it is treated.
5. Common sources of lead intoxication , and what irreversible consequences poisoning can lead to.
6. Is it possible to get intoxicated after exceeding the dose of calcium antagonists , and does this affect human health?

General primary external signs

First of all, motor emotional and arousal arises. As a rule, this is accompanied by liveliness (a characteristic sparkle in the eyes). The initial euphoria is perceived as a pleasant elevation above life's problems. The attitude towards yourself and others changes. This is how a person begins to talk more, and his statements become categorical. When drinking strong drinks, hyperemia (redness) of the skin is observed. This change is usually more pronounced in the upper part of the body, especially on the face; dilation of the pupils is clearly noticeable.