Carbon monoxide poisoning

Only a few people know what carbon monoxide poisoning is. Another term that is widely known is "carbon monoxide poisoning", which is absolutely the same thing. Such intoxication is very dangerous and often ends in death if measures are not taken in a timely manner. Moreover, the main danger is that a person does not feel the presence of gas in the air, quickly loses consciousness and dies.

Carbon monoxide is a substance produced by the incomplete combustion of carbon, which often occurs when oxygen is limited. Initially, it is a gaseous substance without a characteristic aroma or color. Due to its lightness, the gas tends to accumulate in the upper air layers - for example, closer to the ceiling.

Carbon monoxide poisoning is commonly known as “carbon monoxide poisoning”: it can be easily caused by improper use of gas and especially stove heating, ignoring safety precautions when working with a car in a garage, as well as during fires, etc. [ 1 ]

Epidemiology

Carbon monoxide poisoning is one of the most common intoxication injuries caused by exposure to gaseous substances. For example, in the United States, more than 2,000 people die from such poisoning every year, and this does not include cases related to fires. From 2001 to 2003, more than fifteen thousand victims were hospitalized in intensive care units with a diagnosis of carbon monoxide poisoning. In this case, the intoxication was both accidental and intentional - with the purpose of suicide. More than half of the patients suffered as a result of a malfunction of the exhaust system of the furnace heating.

Almost every second survivor of carbon monoxide poisoning experiences long-term mental disorders. [ 2 ]

Causes carbon monoxide poisoning

The most common sources of carbon monoxide poisoning are: [ 3 ], [ 4 ]

• working cars;
• gas-fired water heaters;
• gas fired ovens;
• ovens and household gas cookers;
• charcoal grilling devices;
• preserved blood products used for transfusion;
• units used for ice resurfacing;
• boats, motor devices, generators;
• anesthetic devices that use a reversible absorption circuit;
• propane forklifts;
• areas of active fires, coal mines.

Risk factors

At the moment, carbon monoxide poisoning is registered much less frequently than, for example, a hundred years ago, when houses were mainly heated by stoves. Nevertheless, there are quite a lot of possible sources of intoxication in our time:

• living spaces heated by gas stoves and fireplaces;
• baths;
• auto repair shops, garages;
• manufacturing plants that use carbon monoxide;
• fires in enclosed spaces – for example, in elevators, shafts, basements, etc.

People living in houses with stove heating, car enthusiasts and mechanics, miners, and firefighters are especially at risk. People with unstable psyche and those who regularly abuse alcohol often become victims of carbon monoxide poisoning.

Pathogenesis

The density of carbon monoxide is 0.968 of the specific gravity of air under natural conditions. The substance can easily penetrate into the bloodstream, where it combines with hemoglobin: carboxyhemoglobin is formed. The degree of affinity of hemoglobin and carbon monoxide is high, so CO is present mainly in the blood, and only in small quantities - up to 15% in tissues.

Carbon monoxide is released by intrahepatic degradation of methylene chloride, with the maximum detectable concentration occurring eight or more hours after the onset of intoxication.[ 5 ]

The determining effect of carbon monoxide in poisoning is the failure of such a property of hemoglobin as oxygen binding. As a result, even with adequate partial pressure of oxygen, its content in the arterial flow is greatly reduced. In addition, carbon monoxide shifts the dissociation curve of HbO ₂ to the left, which leads to a decrease in the transfer of oxygen to tissues. The toxic effect of the gas is caused not only by the formation of carboxyhemoglobin, but also by the formation of carboxymyoglobin, a compound of myoglobin with carbon monoxide. It is known that the compound directly changes the processes of cellular respiration. Over time, oxidative degradation of lipids develops, and brain activity is disrupted. [ 6 ]

Symptoms carbon monoxide poisoning

The clinical picture of carbon monoxide poisoning has several degrees of severity, which are characterized by different manifestations and their intensity.

The mild degree is characterized by the following initial signs:

• general state of weakness;
• increasing pain in the head (usually in the forehead and temples);
• sensation of pulsating beats in the temple area;
• auditory noise;
• dizziness;
• deterioration of vision, veil, clouding;
• dry cough;
• feeling of lack of air, difficulty breathing;
• lacrimation;
• nausea;
• redness of the skin of the face, extremities, conjunctiva of the eyes;
• increased heart rate;
• "jump" in blood pressure.

In moderate carbon monoxide poisoning, symptoms increase and worsen:

• consciousness becomes clouded, the flesh becomes lost;
• vomiting appears;
• auditory and visual hallucinations occur;
• loss of coordination of movements;
• a feeling of pressure behind the breastbone appears.

In severe cases, other serious symptoms are added:

• muscle functionality decreases to the point of paralysis;
• the person loses consciousness, and a comatose state may develop;
• convulsions appear;
• pupils dilate;
• involuntary release of urine and feces is possible;
• the pulse is weak and rapid;
• the skin and mucous membranes acquire a bluish tint;
• breathing movements become shallow and intermittent.

As you can see, the color of the skin in carbon monoxide poisoning changes depending on the degree of intoxication, ranging from deep red to bluish. In the fainting form, which is an atypical manifestation of poisoning, the skin and mucous membranes may be pale and even grayish.

Less often, acute carbon monoxide poisoning manifests itself in the so-called euphoric form: the victim experiences psychomotor agitation, causes unreasonable laughter or crying, and behavior becomes inadequate. Then, signs of respiratory and cardiac failure increase, and the person loses consciousness.

Chronic carbon monoxide poisoning is characterized by complaints of constant headaches, fatigue, apathy, sleep problems, poor memory, periodic "lapses" in orientation, frequent and unstable heartbeat, pain behind the breastbone. Vision is impaired: color perception changes, the visual field narrows, accommodation is impaired. Symptoms of problems with the central nervous system increase, which manifests itself in the form of asthenia, dysfunctions of the autonomic nervous system, vascular spasms, hypertension, myocardial dystrophy. When conducting an ECG, focal and diffuse pathological signs, coronary changes are detected. Women experience menstrual cycle irregularities, problems with pregnancy. Men note sexual weakness. [ 7 ]

Chronic poisoning can become a trigger for the development of atherosclerosis and endocrine disorders: patients often develop thyrotoxicosis.

Complications and consequences

The long-term effects of carbon monoxide poisoning are difficult to predict, since the compounds formed in the blood are quite strong. In addition, carbon monoxide can change the structure of hemoglobin, which negatively affects the mechanism of oxygen transfer to tissues. The transport properties of the blood are disrupted, chronic hypoxia develops, which adversely affects the functional capacity of the brain, cardiovascular system, liver and kidneys.

Carbon monoxide has a long-term toxic effect on all tissues in the body. This compound binds to myoglobin, disrupts the contractile function of the myocardium, which leads to poor circulation and lack of oxygen in the organs.

If we follow the statistics of intoxication, a person who has survived carbon monoxide poisoning may die a few years later from a heart attack associated with myocardial damage.

Other adverse effects may include:

• memory impairment;
• deterioration of mental abilities;
• myopathy;
• migraines;
• chronic dyspepsia.

According to experts, even after intensive treatment, neurological disorders persist for at least three years in people poisoned by carbon monoxide. The possibility of irreversible damage to cellular structures is also not excluded. [ 8 ]

Causes of Death from Carbon Monoxide Poisoning

The comatose state and death of the victim usually occur as a result of paralysis of the respiratory center. In this case, heartbeats can be recorded for some time after breathing stops. There are many cases of death from the effects of intoxication even several weeks after the incident.

Some patients develop complications in the form of inflammatory processes in the respiratory tract and lungs. Death from such complications is second only to depression and paralysis of the respiratory center.

As a rule, severe forms of carbon monoxide poisoning are fatal. In the long term, negative consequences can develop even after moderate forms of intoxication.

Diagnostics carbon monoxide poisoning

Since the clinical picture of carbon monoxide poisoning is often vague, without various and specific symptoms, a medical specialist can easily make a mistake and make an incorrect diagnosis. There are many known cases when moderate poisoning with vague symptoms was taken for a viral infection. Therefore, doctors are advised to be very careful, and at the slightest suspicion of carbon monoxide poisoning, to conduct a thorough diagnosis using all the necessary procedures. For example, gas intoxication should never be ruled out if non-specific virus-like symptoms are detected in patients living in the same living space - especially if the house has a stove or fireplace heating.

Tests are the basis for diagnosing carbon monoxide poisoning. First of all, the carboxyhemoglobin content in the blood should be determined: a CO-oximeter is used for this purpose. It is possible to take both venous and arterial blood for testing. A high level of carboxyhemoglobin is a 100% indicator of carbon monoxide intoxication. But there are situations when this level is underestimated due to its rapid decline. For example, this happens if the victim is urgently evacuated from a gas source, or oxygen inhalation is performed on the way to the hospital (before taking blood for analysis).

Instrumental diagnostics are not decisive, but only act as a supplement when making a diagnosis, as it helps to detect some auxiliary signs - for example, electrocardiography is performed for chest pain, and for neurological symptoms - computed tomography of the brain. Changes in the CT image are noticeable already 12 hours after carbon monoxide poisoning, which was accompanied by loss of consciousness. Symmetrical foci of rarefaction in the area of the pale globe, putamen and caudate nucleus are usually visualized. Such changes that appear during the first day indicate an unfavorable prognosis. And vice versa - the absence of pathological changes indicates a likely positive outcome.

Differential diagnostics are carried out with influenza and other viral infections, alcohol intoxication, overdose of sedatives and hypnotics.

Treatment carbon monoxide poisoning

The main focus of treatment for carbon monoxide poisoning is to establish gas exchange processes. First, the patient is provided with breathing 100% oxygen using a mask or endotracheal tube. This measure helps to increase the concentration of dissolved oxygen in the bloodstream, while simultaneously stimulating the dissociation of carboxyhemoglobin. If hospitalization and oxygenation are prompt, the mortality rate is reduced to 1-30%.

Initial treatment measures may include:

• placement of an oxygen mask;
• breathing a mixture of oxygen and carbon dioxide (called carbogen);
• artificial ventilation;
• hyperbaric chamber therapy.

In addition, an antidote is administered without fail.

After the victim's condition has stabilized, general treatment begins in order to restore the body's basic functions and prevent the negative consequences of hypoxia.

In addition to the main treatment, a diet is prescribed: the diet is enriched with vitamin-rich foods rich in antioxidants. The diet should include a dominant amount of fruits and berries: it is recommended to eat blueberries, red and blue grapes, cranberries, currants, pomegranate. Freshly squeezed citrus and carrot juices, green tea, pu-erh have a good effect. [ 9 ]

First Aid for Carbon Monoxide Poisoning

The prognosis for the patient directly depends on the speed and timeliness of first aid, so even if you suspect carbon monoxide poisoning, you should immediately call an ambulance.

General measures for providing emergency care are as follows:

• The source of carbon monoxide emission is eliminated and neutralized, and the poisoned person is removed or taken out into fresh air.
• Provide maximum oxygen access: loosen the collar, unfasten the belt, etc.
• They try to activate blood circulation: rub the chest, give hot tea or coffee to drink.
• They do everything they can to prevent the victims from losing consciousness: they bring them ammonia, spray them with cool water, and slap them on the cheeks.
• If the victim's breathing has stopped or the pulse has disappeared, emergency measures should be taken: artificial respiration, manual heart massage.

Antidote for carbon monoxide poisoning

The antidote is Acizol, which is administered in the amount of 60 mg as an intramuscular injection three times during the first 24 hours of poisoning, then once a day in the amount of 60 mg for two days in a row. The administration of the antidote is combined with fibrobronchoscopy in case of damage to the respiratory system.

If the victim can take the drug on their own, it is prescribed in capsule form: one capsule 4 times on the first day, then one capsule twice a day for a week. The maximum permissible dosage of the antidote for an adult is 4 capsules (or 480 mg).

Acyzol enhances the effect of general pathogenetic treatment, inhibits the formation of carboxyhemoglobin by affecting the combined interaction of hemoglobin subunits. As a result, the degree of relative affinity of hemoglobin and carbon monoxide decreases, the oxygen-binding and gas-transporting abilities of the blood are optimized. In addition, the antidote reduces the degree of oxygen starvation, increases the body's hypoxic resistance. [ 10 ]

Medicines that a doctor may prescribe

Carbon monoxide poisoning always requires urgent hospitalization, even if the victim appears to be feeling well. In addition to oxygen therapy, the patient is given intravenous medications, depending on which organs and systems failed first. Cardiovascular drugs, vitamins, anticonvulsants, etc. are often prescribed.

Anti-inflammatory drugs to relieve inflammation of the respiratory tract
Pulmicort	A glucocorticosteroid drug with a strong anti-inflammatory property, reducing the degree of bronchial obstruction. The dosage for an adult patient is up to 800 mcg per day, taken in 2-4 inhalations. The amount of the drug can be changed at the discretion of the doctor. Possible side effects include: allergies, sleep disorders, cough, irritability.
Budesonide	An active synthetic glucocorticoid drug that prevents and cures inflammatory diseases of the respiratory tract. It can be prescribed in quantities from 200 to 1600 mcg per day, in 2-4 inhalations. Possible side effects: oral and throat candidiasis, hypersensitivity reactions, cough, wheezing, throat irritation.
Anticonvulsants to reduce muscle hypertonicity
Levodopa and carbidopa	Anticonvulsant antiparkinsonian drug, prescribed in individual dosages. Can be used from the age of 18.
Amantadine	Antiviral and simultaneously antiparkinsonian drug. Taken orally, after meals, in an individually selected dosage. Treatment may be accompanied by nausea, dry mouth, dizziness. Simultaneous intake of alcohol and Amantadine is prohibited.
Painkillers to ease the condition
Novigan	An analgesic and antispasmodic. Prescribed between meals, one tablet three times a day. Contraindicated for children under 16 years of age. Possible side effects: abdominal pain, allergic reactions, dyspepsia.
Ibuprofen	Non-steroidal anti-inflammatory drug, taken after meals, 200-400 mg, three times a day. Duration of treatment is no more than three days. Side effects: abdominal pain, digestive disorders.
Vitamin preparations to accelerate the destruction of carboxyhemoglobin
Cocarboxylase	A vitamin B1 preparation used as part of a complex treatment. It is administered intramuscularly at 50-100 mg per day for 15-30 days in a row. During treatment, allergic reactions in the form of redness, itching, and swelling are possible.
Sorbent agents for neutralizing toxins
Polysorb	A colloidal silicon dioxide preparation with enterosorbent activity. Taken between meals, in individual dosages. Treatment can last up to two weeks. Several courses can be taken with an interval of 2-3 weeks between them. Side effects are rare: constipation, allergy.

Prevention

To reduce the risk of carbon monoxide poisoning, it is recommended to follow these simple rules:

• the operation of stoves and fireplace inserts must be carried out in compliance with all safety regulations;
• it is necessary to regularly inspect and test the ventilation system in the house, check the patency of the chimney and ventilation ducts;
• installation of stoves and fireplace inserts, their repair and maintenance should be carried out only by professional specialists;
• the car engine can only be started in an open garage (according to statistics, to get carbon monoxide poisoning, it is enough to be in a closed space with the engine running for five minutes);
• You cannot stay in a parked, closed, running car for a long time, and even more so, you cannot sleep in it;
• If there are any signs of carbon monoxide spreading and poisoning, it is important to fill the room with fresh air as soon as possible and, if possible, go outside.

Carbon monoxide is an insidious and dangerous substance that acts quickly and almost imperceptibly. Therefore, it is much easier to prevent the problem in advance by simply following all the rules and recommendations. [ 11 ]

Forecast

What do experts say about the prognosis of the clinical course of acute carbon monoxide poisoning? In most cases, such a prognosis depends on the extent to which the respiratory tract is affected, as well as on the recorded maximum level of carboxyhemoglobin in the victim's blood. Doctors assess the condition of the victim using the following criteria:

• general health condition, individual physiological characteristics of the patient (the worst prognosis is announced for weakened patients suffering from chronic pathologies, for the elderly, pregnant women and children);
• the duration of exposure and the concentration of carbon monoxide in the air the victim breathed;
• vigorous activity during intoxication (high physical activity, intense breathing movements contribute to a more rapid development of poisoning).

Unfortunately, acute carbon monoxide poisoning often ends in death: this is due to both the vagueness of clinical symptoms and the lack of or untimely provision of first aid to the victim.