Gas poisoning

Introduction to gas poisoning Carbon monoxide poisoning (carbon monoxide poisoning) is mostly due to the fact that there is no chimney or chimney clogging in the coal stove, or because the wind blows into the chimney, causing the gas to flow back into the chamber, or because the room is not ventilated, the smelting workshop is not well ventilated, the engine exhaust and Gunpowder explosions contain large amounts of carbon monoxide. The mechanism of poisoning is that the affinity of carbon monoxide and hemoglobin is 200-300 times higher than that of oxygen and hemoglobin. Therefore, carbon monoxide is easily combined with hemoglobin to form carboxyhemoglobin, which loses oxygen carrying capacity and causes tissue suffocation. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: pulmonary edema, brain edema, proteinuria

Cause of gas poisoning

Cause (70%):

Carbon monoxide is a product of incomplete combustion of carbonated materials and is poisoned by inhalation through the respiratory tract. After inhalation through the respiratory tract, carbon monoxide enters the blood circulation through the alveoli and immediately combines with hemoglobin to form carboxyhemoglobin, which makes hemoglobin lose its ability to carry oxygen. Moreover, the presence of carboxyhemoglobin also inhibits the dissociation of oxyhemoglobin, inhibits the release and transmission of oxygen, and causes acute hypoxemia in the body.

(1) Industrial, steelmaking, iron making, coking; chemical industry ammonia, formaldehyde, etc. must be exposed to carbon monoxide.

(2) In the course of life, carbon monoxide poisoning can occur in a poorly ventilated room for coal heating or a gas heater shower.

Gas poisoning prevention

1. It should be widely publicized that there should be safety settings (such as chimneys, small ventilation windows, wind buckets, etc.) when using coal fire indoors, indicating the possible symptoms and first-aid knowledge of gas poisoning, especially the harm and seriousness of gas to small infants. The coal stove chimney should be installed reasonably, and the coal stove without chimney should be placed outdoors at night.

2. Do not use eliminated water heaters, such as in-line water heaters and flue-type water heaters. These two types of water heaters are prohibited from being produced and sold by the state. Do not use overtime service water heaters. It is best to install a water heater for professional installation. Do not install, dismantle or modify the burning appliance by yourself. Do not close the bathroom doors and windows when showering in winter, do not take too long shower time.

3. When driving, do not let the engine idle for a long time. When the car is stopped, do not open the air conditioner for too long. Even when driving, you should always open the window to allow convection of the air inside and outside the car. If you feel unwell, stop and rest. When driving or taking an air-conditioned car, if you feel dizzy, heavy, and weak in your limbs, you should open the window and breathe fresh air in time.

4. Install a carbon monoxide alarm where carbon monoxide may be produced. The carbon monoxide alarm is a device specially designed to detect the concentration of carbon monoxide in the air. It can alarm when the concentration of carbon monoxide exceeds the standard, and some can forcibly open windows or exhaust fans to keep people away from carbon monoxide.

Gas poisoning complications Complications pulmonary edema cerebral edema proteinuria

Can be complicated by pulmonary edema, cerebral edema, skin damage, acute kidney damage.

1. Pulmonary edema: CO is not a irritating gas. It is a suffocating harmful gas. It can cause severe hypoxia in the body and has a certain direct toxic effect on tissue cells, especially on the central nervous system and lung. Hypoxia and CO can increase pulmonary capillary and alveolar permeability and cause pulmonary edema. The clinical features of pulmonary edema are rapid onset, and a few cases of delayed pulmonary edema occur in a few hours or even 24 hours. Patients with coma can not complain of chest tightness, belching and difficulty breathing, and rarely have cough and irritability symptoms, mainly by clinical observation. It is characterized by shortness of breath, overflowing mouth or nose, or a lot of pink or white foamy secretions. The lungs smell a lot of wet voices, and the nursing staff should closely observe the condition.

2, cerebral edema: brain cells are most sensitive to hypoxia, hypoxia caused brain cell edema, vascular permeability changes, cerebral edema. Early diagnosis is difficult, mainly based on clinical manifestations and signs, manifested as increased limb muscle tension, convulsions, fundus changes and even cerebral palsy.

3, skin damage: CO poisoning skin damage, can occur alone, can also occur on the basis of limb crush injury, but limb crush injury is not necessarily accompanied by skin damage, skin damage and CO poisoning degree, length of time And individuals are related to hypoxia sensitivity, which can form erythema and blisters. The compression site is more likely to occur, such as facial, shoulder, limbs and other parts of the local redness, stiffness (slightly higher than normal skin, clear boundaries, irregular shape, pressure fade), pain, tenderness can also appear blisters or ulceration Damage that occurs at the joint site can be accompanied by dyskinesia.

4, acute kidney damage: CO poisoning kidney hypoxia, damage, red blood cells in the urine, proteinuria and caste and other kidney damage.

Symptoms of gas poisoning Common symptoms Drowsiness, coma, head, bloating, nausea, shortness of breath, cyanide burn, combined with poisoning, tinnitus, limb weakness, convulsion

Mild: headache, dizziness, palpitation, nausea, vomiting.

Moderate: flushing, red cherry lips, sweating, irritability, gradual coma.

Severe: unconsciousness, dementia, incontinence, cold limbs, dilated pupils, decreased blood pressure, weak or stopped breathing, increased body temperature, stiff or soft limbs, myocardial damage or arrhythmia, various reflexes disappear, Or into a pathological reflex.

Gas poisoning inspection

1. Determination of carboxyhemoglobin in blood

Normal human blood carboxyhemoglobin content can reach 5% to 10%, a small amount from endogenous carbon monoxide, O.4% to O.7% mild carbon monoxide poisoning, blood carboxyhemoglobin can be higher than 10% Moderate poisoning can be higher than 30%, and severe poisoning can be higher than 50%. However, the determination of carboxyhemoglobin in blood must be timely. After 8 hours of exposure to carbon monoxide, carboxyhemoglobin can be reduced to normal and may not be in parallel with clinical symptoms.

2. EEG

It has been reported that 54% to 97% of patients with acute carbon monoxide poisoning can find abnormal EEG, which is characterized by an increase in low amplitude and slow wave. Generally, the theta waves and delta waves in the forehead and ankle are often associated with clinical disturbances of consciousness. Some comatose patients can also have special three-phase waves, similar to the waveforms in hepatic coma. Pseudo paroxysmal spine slow waves or slow and slow waves. Some patients with acute carbon monoxide poisoning may have a long-term abnormality of ESD.

3. Brain evoked potential examination

In the acute phase of delayed carbon monoxide poisoning and late encephalopathy, the visual evoked potential VEP100 prolonged latency, the abnormal rates were 50% and 68%, respectively, and the recovery period was reduced to 5% and 22% of the median nerve somatosensory evoked potential (SEP). See N32 and other long-term latent components selective damage, the abnormal rate of both types of patients are more than 70%, and the recovery of brainstem auditory evoked potential (BAEP) abnormality is closely related to the degree of disturbance of consciousness, and poisoning The outcome of the disease is parallel.

4. Brain imaging examination

In patients with carbon monoxide poisoning, the CT scan of the brain in the acute phase and the occurrence of delayed encephalopathy showed that the main abnormalities were bilateral cerebral cortical white matter and a symmetrical sensation of density reduction in the globus pallidus or internal capsule. Later, ventricular enlargement or sulcal widening was observed. The abnormal rates were 41.2% and 87.5%, respectively. The prognosis of patients with abnormal brain CT was better. The patients with CT abnormalities had more than 48 hours of coma. However, there is no CT change in the early stage of delayed encephalopathy. The above CT abnormalities are usually found after 2 weeks of delayed onset of encephalopathy, so it is not as sensitive as brain evoked potentials and EEG.

5. Blood, urine, cerebrospinal fluid routine test

The total number of peripheral red blood cells, white blood cells and neutrophils increased. The number of white blood cells in severe poisoning was higher than 18×109/L. One-fifth of patients with urinary protein can be positive in patients with 40% urine sugar. Cerebrospinal fluid pressure and routine majority are normal.

6. Blood biochemical examination

Serum ALT activity and transient increase in non-protein nitrogen. Lactate and lactate dehydrogenase activity increased after acute poisoning. Serum AST activity also began to increase in the early 24 hours to the highest value. If it exceeds the normal value by 3 times, it often indicates that the condition is severe or there is complication with rhabdomyolysis, the blood creatine phosphokinase (CPK) activity is significantly increased. . Blood gas examination shows that the blood oxygen partial pressure normal blood oxygen saturation can be normal, the blood pH is lowered or normal, and the blood carbon dioxide partial pressure often has a compensatory decrease in blood potassium.

7. Electrocardiogram

Some patients may have ST-T changes, as well as ventricular premature contractions, conduction block, or transient sinus tachycardia.

Gas poisoning diagnosis and identification

diagnosis

According to the history and symptoms can be diagnosed, carbon monoxide test method:

1 blood is cherry red;

2 take a drop of blood and add a cup of water to a reddish color (normal person is yellow);

3 Take a few drops of blood and add 10ml of water, add a few drops of 10% sodium hydroxide, which is pink (normal human blood is green).

Dizziness, headache, tinnitus, vertigo, weakness and general malaise, nausea, vomiting, chest tightness, fainting, coma, shortness of breath, decreased blood pressure, and even death, symptoms and carboxyhemoglobin How much is related to the head swelling, headache, nausea when the blood contains 10% to 20% carboxyhemoglobin; when it reaches 30% to 50%, there is weakness, vomiting, dizziness, confusion, tremor, or even collapse; to 50% 60% have coma and convulsions; to 70%-80%, the respiratory center is paralyzed, and the heartbeat stops. Because the carboxyhemoglobin is red, the patient has no cyanosis, and the skin and lip color are cherry red.

Differential diagnosis

Must be identified with cerebrovascular accidents, encephalitis, diabetes, uremia and other diseases.

1. Encephalitis (forest encephalitis), forest encephalitis, also known as the Soviet spring and summer encephalitis or Far-Ear Brain Encephalitis, is a natural epidemic acute central nervous system infectious disease caused by the forest encephalitis virus through the hard sputum. The clinical features are sudden high fever, disturbance of consciousness, headache, strong neck, upper limbs and neck and scapular tendon, and sequelae are more common.

2. Diabetes: It is a common disease caused by the interaction of genetic and environmental factors. Clinically, hyperglycemia is the main indicator. Common symptoms include polydipsia, polyuria, polyphagia and weight loss. Diabetes can cause multiple systemic damage. It causes absolute or relative secretion of insulin and the sensitivity of target tissue cells to insulin, causing a series of metabolic disorders such as protein, fat, water and electrolytes, of which a high blood sugar is the main marker.

3. Uremic: In fact, it means that the human body can not produce urine through the kidneys, and the waste generated by metabolism in the body and excessive water are excreted from the body, causing poison. Modern medicine believes that uremia is a complex syndrome caused by the disorder of biochemical processes inside the body after loss of renal function.

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