Poisoning Department of 307 Hospital of the Chinese People's Liberation Army
Wang Xingwang
(Attending physician) review
Poisoning Department of 307 Hospital of the Chinese People's Liberation Army
Carbon monoxide poisoning, also known as gas poisoning, is caused by inhalation of the products of incomplete combustion of carbon containing substances through the respiratory tract.The affinity between carbon monoxide and hemoglobin is 200~300 times higher than that between oxygen and hemoglobin, so carbon monoxide is very easy to combine with hemoglobin to form carboxyhemoglobin, which makes hemoglobin lose its oxygen carrying capacity and role. The clinical manifestation is mainly hypoxia, causing tissue asphyxia.It has toxic effects on tissues and cells of the whole body, especially on the cerebral cortex.Common causes include occupational exposure due to leakage of raw heating gas
Mild symptoms include dizziness, headache, nausea, vomiting, weakness of limbs, etc.Moderately severe symptoms may cause dyspneaLoss of consciousness、coma。When the poisoning is serious, the patient quickly enters into a deep coma, and various reflexes disappear,incontinence, cold limbs.Carbon monoxide poisoning is not an infectious disease and will not infect others
The treatment is to quickly move the patient to a place with fresh and circulating air to keep the respiratory tract unobstructed.For patients with moderate to severe coma, lateral position should be adopted to avoid aspiration.Give patients oxygen therapy, such as nasal tube oxygen or mask oxygen.Inhaling pure oxygen can shorten the half discharge period of carboxyhemoglobin and accelerate the discharge of carbon monoxide.Hyperbaric oxygen therapyIt is a specific treatment for carbon monoxide poisoning. Dehydrating agents such as mannitol can be used for drug treatment to reduce intracranial pressure and prevent the formation of brain hernia.For patients with frequent convulsions, sedatives such as diazepam can be used to control convulsions.
The prognosis of carbon monoxide poisoning mainly depends on the severity of poisoning, timely treatment and individual differences of patients.Mild and moderate poisoning requires rapid improvement of patients' hypoxia status, and most patients can fully recover without sequelae after timely rescue.However, if the rescue is not timely or the measures are improper, it may develop into severe poisoning and produce sequelae.Severe poisoning is often accompanied by such sequelae as impaired comprehension, memory, and intellectual paralysis.
Chinese name
carbon monoxide poisoning
Foreign name
carbon monoxide poisoning
Alias
Gas poisoning
Visiting department
Emergency department or hyperbaric oxygen department
Multiple population
People with special environment and special occupation
Common location
The main clinical manifestation is hypoxia, and its severity is related to HbCO（Carboxyhemoglobin）The saturation of is proportional
Common causes
Boiler heating, gas leakage, occupational exposure, etc
In the production process of steelmaking, coking, kiln, etc., a large amount of carbon monoxide may be produced due to equipment failure, leakage or operation error.For example, blast furnace gas producer gas contains 30% - 35% carbon monoxide, and water gas contains 30% - 40% carbon monoxide.
If the furnace door and kiln door are not closed tightly, gas pipeline leakage or coal mine gas explosion may also produce a large amount of carbon monoxide, resulting in inhalation poisoning.
CO leakage in daily life
One of the most common causes of CO poisoning is the use of coal stoves for heating or gas leakage in families.The carbon monoxide content in the gas produced by the coal furnace is as high as 6% - 30%. If the protection is not paid attention to during application, poisoning may occur.
When using coal stove, charcoal and other fuels in a room with closed doors and windows, carbon monoxide will be produced during combustion.If the chimney or ventilation pipe is blocked, this gas will accumulate, thus increasing the risk of poisoning.
CO generation in fire
1. When a fire burns, in addition to releasing a large amount of smoke, it will also release a large amount of harmful gases such as carbon monoxide.
The concentration of carbon monoxide in the air at the fire scene is as high as 10%, which can also cause poisoning of on-site personnel.
CO production in animal husbandry
The use of coal stoves for heating in the feedlot without smoke exhaust facilities may lead to carbon monoxide poisoning.
Pathogenesis
Combination of carbon monoxide and hemoglobin
When carbon monoxide enters the human body, it will quickly combine with hemoglobin in the blood to form carboxyhemoglobin (COHb).
The affinity between carbon monoxide and hemoglobin is about 200~300 times greater than that between oxygen and hemoglobin. Therefore, even in a low concentration of carbon monoxide environment, a large amount of COHb can be formed.
Loss of oxygen carrying capacity of hemoglobin
Due to the formation of COHb, the original oxygen carrying capacity of hemoglobin is gradually lost, resulting in a significant reduction of oxygen that can be transported to tissues and cells in the blood.
Body hypoxia
With the loss of oxygen carrying capacity of hemoglobin, various tissues and cells of the body appear hypoxia.This hypoxia state will affect the normal metabolism and function of cells, especially the organs and systems with high demand for oxygen, such as the central nervous system.
Functional damage of central nervous system
Under the condition of hypoxia, the central nervous system is first affected, and headache, dizziness, nausea, vomiting, fatigue and other symptoms may appear.As the degree of poisoning deepens, consciousness disorder, coma and even death may occur.
Multiple organ disease
In addition to the central nervous system, other organs such as the heart and kidney will also be damaged due to hypoxia, resulting in multiple organ diseases.
Combination of carbon monoxide and cytochrome oxidase
Carbon monoxide can also combine with the iron divalent of the reduced cytochrome oxidase in cells, inhibit the activity of cytochrome oxidase, affect the respiration and oxidation process of cells, and further hinder the use of oxygen.
epidemiology
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Carbon monoxide poisoning occurs all over the world, but its incidence in winter in northern China is significantly higher.This is related to the way of heating in northern areas and the closed indoor environment in winter.
At the same time, there are reports of non occupational carbon monoxide poisoning incidents all over the country, not only in cold regions (such as Qinghai Province), but also in cold regions (such as Beijing, Shanxi, Hebei), hot summer and cold winter regions (such as Shanghai, Shandong, Anhui), and hot summer and warm winter regions (such as Guangxi, Chongqing).Carbon monoxide poisoning events mainly occur in the winter when household heating and domestic hot water are used.This is related to the increasing demand for heating in winter and the rapid accumulation of carbon monoxide in the room due to poor indoor ventilation.
symptom
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Carbon monoxide poisoning is not infectious and has no source of infection due to the impact of living or working environment.
The clinical manifestation of carbon monoxide poisoning is mainly hypoxia, and its severity is proportional to the saturation of HbCO (carboxyhemoglobin).In case of mild poisoning, the patient may have symptoms such as headache, weakness, dizziness, and dyspnea during labor, with HbCO saturation of 10%~20%.In case of moderate poisoning, the patient's lips are cherry red, with nausea, vomiting, confusion, collapse or coma, and the HbCO saturation is 30%~40%.In case of severe poisoning, the patient is in deep coma, accompanied by high fever, limb muscle tension enhancement and paroxysmal or tonic spasm, and HbCO saturation is greater than 50%.Some patients may also have skin symptoms such as blisters and redness.
The symptoms of carbon monoxide poisoning vary according to the degree of poisoning.The following are common symptoms of mild, moderate and severe carbon monoxide poisoning:
Mild poisoning
Headache: Carbon monoxide prevents oxygen from entering body cells, which can lead to headaches.Slight dizziness or dizziness: due to insufficient oxygen supply to the brain, slight dizziness or dizziness may occur.Nausea and vomiting: carbon monoxide poisoning may cause nausea and vomiting.Faster heartbeat: As the body needs more oxygen, the heart will beat faster to try to compensate.Shortness of breath: As the body needs more oxygen, breathing will become more rapid.Fatigue: The body does not get enough oxygen supply, which may lead to fatigue.There may also be dizziness, tinnitus, limb weakness and other symptoms.
Moderate poisoning
Headache: It may be manifested as total headache or temporal pain.Nausea and vomiting: usually accompanied by headache and dizziness.Vertigo: It may cause dizziness and vertigo, even imbalance and confusion of consciousness.Shortness of breath: may lead to shortness of breath, increase heart load, or even lead to palpitation.Fatigue and languor: The body may feel fatigue, languor and weakness.Muscle pain: It may cause muscle pain and joint pain, which is manifested as muscle soreness or stiffness of the whole body.There may also be insomnia, anxiety and other neuropsychiatric symptoms.
Severe poisoning
The patient may show a state of decortication, that is, coma with eyes open.When the body temperature rises, the respiratory rate increases, and in severe cases, respiratory failure will occur.The pulse is fast and weak, and the blood pressure drops.If the concentration of carbon monoxide in the air is very high, the patient may suddenly become unconscious, convulsion, dyspnea and respiratory paralysis after several deep breaths, which is called lightning poisoning.
Medical treatment
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Visiting department
Emergency department or hyperbaric oxygen department
Diagnostic basis
Find out if the patient has a history of exposure to gas or carbon monoxide, such as using a gas water heater, coal-fired boiler, etc.Observe whether the patient has symptoms such as dizziness, headache, nausea, vomiting, and disturbance of consciousness, and whether the skin and mucous membrane are cherry red.
laboratory examination
Determination of blood carboxyhemoglobin (COHb): The concentration of COHb is an important indicator for diagnosing carbon monoxide poisoning.The COHb concentration of normal people generally does not exceed 2%. The COHb concentration is 10%~20% in mild poisoning, 30%~40% in moderate poisoning, and more than 50% in severe poisoning.
Arterial blood gas analysis: it can understand the patient's partial pressure of oxygen (PaO2) and arterial oxygen saturation (SaO2), and whether there is metabolic acidosis.
Serum enzymology examination: it is helpful to eliminate coma caused by other factors.
Auxiliary examination: ECG, head CT, MRI, EEG and other examinations are helpful to understand the patient's specific condition and complications.
treatment
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General treatment
Move the patient quickly to a place with fresh air, lie in bed and rest, and keep the respiratory tract unobstructed.Keep warm to prevent getting cold.
Oxygen therapy: for mild poisoning, nasal catheter can be given oxygen inhalation;Patients with moderate and severe poisoning should be actively given hyperbaric oxygen treatment.Hyperbaric oxygen treatment can accelerate the dissociation of COHb and promote the discharge of CO.
Drug treatment: Cytidine diphosphate choline, aspirin and other drugs can be used for treatment.For patients with moderate and severe poisoning, hormone pulse therapy and ganglioside therapy can be used to repair nerve sheath damage.
Treatment of complications
If the patient has cerebral edema, pulmonary edema, myocardial damage and other complications, the corresponding treatment should be actively given.
prognosis
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The prognosis of carbon monoxide poisoning mainly depends on the severity of poisoning, the timeliness of rescue and the basic health status of patients.Generally speaking, patients with mild poisoning can fully recover and have a good prognosis after timely treatment and rest.Patients with moderate poisoning may have some complications, such as brain edema, pulmonary edema, etc., but after active treatment and rehabilitation, most patients can also gradually recover.However, patients with severe poisoning may have serious complications, such as myocardial damage, coma, delayed encephalopathy, etc. The prognosis is poor, and some patients may leave permanent neurological damage or disability.
Preventive methods
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Avoid using gas or burning coal in an enclosed environment: turning on the heating or air conditioning in an enclosed vehicle may cause carbon monoxide poisoning, and closing the windows may cause carbon monoxide to accumulate in the vehicle and cannot be discharged.Similarly, burning charcoal in the bedroom may also lead to carbon monoxide poisoning.
Strengthen ventilation: When using fuel gas, coal and other fuels, ensure that the environment is well ventilated to reduce the concentration of carbon monoxide.For example, when using a gas stove, it is better to open a window for ventilation or open a range hood;When using a coal stove for heating or cooking indoors, smoke exhaust pipes shall be installed and kept unobstructed.
Regular inspection and maintenance of equipment: regular inspection and maintenance of gas equipment, gas water heaters and other equipment to ensure their normal operation and prevent leakage and failure.
Installation of alarm: carbon monoxide alarm shall be installed in places where carbon monoxide leakage may occur, such as kitchen, bathroom, etc., so that leakage can be found in time and measures can be taken.
Correct use of fuel: When using coal and other solid fuels, pay attention to that the vent of the coal furnace should be straight to the door. When sealing the fire with coal balls at night, the vent should be properly reserved to prevent carbon monoxide accumulation.At the same time, when purchasing honeycomb briquette, attention should also be paid to the selection of high-quality briquettes to avoid the use of low-quality coal.
History
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Since ancient times, human beings have begun to inhale carbon monoxide in the process of using fire.Carbon monoxide poisoning occurred when living in caves.Although the ancients realized that burning charcoal for heating was easy to be poisoned, they did not know the specific reason, and often attributed the poisoning to suffocation caused by kang or too strong fire or too thick gas.Carbon monoxide poisoning has been recorded in the Ming Dynasty and Qing Dynasty, and these articles have also been reported abroad. Modern scientific research has clarified the mechanism of carbon monoxide poisoning and detoxification, mainly involving the increase of carboxyhemoglobin leading to the decrease of oxygen and hemoglobin, which in turn leads to hypoxemia and cell respiratory dysfunction.
Prolonged exposure to low concentrations of carbon monoxide may also lead to pathological changes such as damaged cytochrome oxidase, decreased mitochondrial function, and decreased production of adenosine triphosphate.The development history of carbon monoxide poisoning is a process from the accumulation of ancient experience to modern scientific cognition and then to modern comprehensive prevention and treatment.With the progress of science and technology and the continuous improvement of human awareness of carbon monoxide poisoning, we have reason to believe that carbon monoxide poisoning will be more effectively solved and prevented in the future.
Research progress
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The main mechanism of carbon monoxide poisoning is to combine hemoglobin competitively to form carboxyhemoglobin (COHb), thereby reducing the oxygen carrying capacity of hemoglobin and leading to tissue hypoxia.However, recent studies have revealed more complex toxic mechanisms:
Mitochondrial dysfunction: carbon monoxide inhibits mitochondrial function, causing neurotoxicity, acidosis, ion imbalance, depolarization, oxidative stress and apoptosis, leading to hypoxic-ischemic brain damage.
Immune inflammatory reaction: excessive carbon monoxide activates platelets, promotes neutrophil activation, adhesion and degranulation, and induces the body to produce immune inflammatory reaction.
Autoimmune reaction: after ACOP, myelin sheath related protein and malondialdehyde form a complex to induce autoimmune cascade reaction and destroy myelin sheath, and carbon monoxide poisoning delayed encephalopathy or legacy neurological sequelae may occur later.
Direct damage: carbon monoxide combines with myoglobin in heart and skeletal muscle, causing direct damage.The treatment of carbon monoxide poisoning has also made great progress.Hyperbaric oxygen treatment can significantly shorten the half clearance time and total clearance time of carbon monoxide, which is a very important treatment method for acute carbon monoxide poisoning.
