Ammonia is a colorless gas with strong pungent taste.Soluble in waterammoniaIt can be used as fertilizer.Ammonia can be liquefied under pressure at normal temperature to form liquid nitrogen, which is convenient for transportation.Ammonia is an important chemical raw material, which is widely used in petroleum smelting, fertilizer manufacturing, synthetic fiber and leather making.Pharmaceutical, plastic, dye and other manufacturing industries.In the production, transportation, storage and use of ammonia, if pipelines, valves, storage tanks, etc. are damaged, ammonia leakage may cause poisoning.Ammonia has irritating and corrosive effects on skin and mucosa. High concentration of ammonia can cause serious consequences, such as chemical laryngitis, chemical pneumonia, etc. Inhalation of extremely high concentration can cause reflex respiratory arrest and cardiac arrest.
Ammonia is one of the common pollutants in buildings.Mainly from high alkaliconcreteThe expansion agent and concrete antifreeze containing urea, these substances, with the change of ambient temperature and humidity, the reduced ammonia slowly releases from the wall, polluting the indoor environment.Ammonia has irritating and corrosive effects on skin and mucous membrane, and high concentration can cause serious consequences, such as chemicaliaryngopharyngitis, ChemistrypneumoniaInhalation of extremely high concentration can cause reflex respiratory arrest and cardiac arrest.However, the amount of ammonia emitted from general decoration materials is less, which mainly causes irritation.The humid areas in the south also have a corrosive effect on furniture and buildings.
Poisoning mechanism
Announce
edit
When ammonia meets water in human tissues, it generates ammonia water, which can dissolve tissuesprotein, andFatIt has saponification effect.Ammonia can destroy the activity of various enzymes in the body and affect tissue metabolism.Ammonia has a strong stimulating effect on the central nervous system.
1. Ammonia is strongly irritant. Inhalation of high concentration ammonia can excite the central nervous system, causing convulsions, convulsions, lethargy and coma.Inhaling extremely high concentrations of ammonia can reflexively cause cardiac arrest and respiratory arrest.
2. Ammonia is an alkaline substance, and ammonia water has corrosive effect.Alkaline burns are more serious than acid burns because of the strong penetrability of alkaline substances. Ammonia burns on the skin are deep, susceptible to infection, and difficult to heal, similar to second degree burns.
3. When ammonia is inhaled into the respiratory tract, it will generate ammonia when encountering water.Ammonia water will invade submucosa, pulmonary interstitium and capillaries through mucosa and alveolar epithelium, causing:
(1) Vocal cord spasm, laryngeal edema, tissue necrosis.Asphyxia may be caused by shedding of necrotic substances.The damaged mucosa is prone to secondary infection.
(2) Tracheal and bronchial mucosa injury, edema, bleeding, spasm, etc.It affects the ventilation function of bronchi.
(3) Pulmonary alveolar epithelial cells, pulmonary interstitium, and pulmonary capillary endothelial cells were damaged, permeability was increased, and pulmonary interstitial edema occurred.Ammonia stimulates sympathetic nerve excitation, makes common lymphatic vessel spasm, impedes lymphatic return, and increases pulmonary capillary pressure.Ammonia destroys pulmonary surfactant.These effects eventually lead to pulmonary edema.
(4) Mucosal edema, increased inflammatory secretion, pulmonary edema, decreased pulmonary surfactant, tracheal and bronchial lumen stenosis and other factors seriously affect the ventilation and ventilation function of the lung, resulting in systemic hypoxia.
clinical manifestation
Announce
edit
When exposed to ammonia, strong irritating odor will be smelled, and eyes will shed tears and tingle.If too thick ammonia water splashes into the eyes, it can damage the cornea and cause corneal ulcer. In serious cases, it can cause corneal perforation, lens opacity, iris inflammation, etc., which can lead to blindness.
Inhalation of ammonia can cause pharyngeal and laryngeal pain and hoarseness.Inhalation of ammonia with high concentration may cause laryngospasm, vocal cord edema and asphyxia.
Ammonia entering the trachea and bronchi will cause coughing, expectoration, and blood in sputum.In severe cases, hemoptysis and pulmonary edema, dyspnea, cluck white or bloody foam sputum, and both lungs are full of large and medium water bubble sounds.
Inhalation of high concentrations of ammonia can induce convulsions, convulsions, lethargy, coma and other consciousness disorders.Breathing and cardiac arrest may occur in individual patients who inhale extremely thick ammonia.
When the secondary infection of lung occurred, the patient had high fever, hemoptysis, yellow sputum, dyspnea, and purple Zhou.Damage to the digestive tract may cause abdominal pain, vomiting, etc., and jaundice and liver function damage (toxic hepatitis) may occur later.
diagnosis
Announce
edit
1. Have a history of illness after exposure to ammonia.
2. The breath and skin smell of ammonia.
3. Clinical manifestations of skin, mucosa and respiratory tract injury.
Diagnostic grading standard
Announce
edit
Ammonia stimulating reaction
Only temporary eye and upper respiratory tract irritation symptoms, no obvious lungpositivePhysical signs.
Mild poisoning
Mild poisoning can be diagnosed according to the following indicators:
1. Tears, sore throat, hoarseness, cough, expectoration with mild dizziness, headache, fatigue, etc;Ocular conjunctiva, pharyngeal congestion, edema, dry rales in the lungs.
2. Chest X-ray signs, enhanced lung markings or blurry edges, consistent with bronchitis or peribronchitis.
3. Blood gas analysis: when breathing air, arterial partial pressure of oxygen is lower than the expected value 1.33-2.66kPa (10-20mmHg).
Moderate poisoning
1. hoarse voice, severe cough, sometimes with bloody sputum, chest tightness, dyspnea, dizziness, headache, nausea, vomiting, fatigue, etc;Mild cyanosis, dry and wet rales in the lungs.
2. Chest X-ray signs: enhanced lung markings, blurred edges or reticular shadows, or decreased transparency of lung fields, or scattered or patchy shadows with blurred edges, consistent with pneumonia or interstitial pneumonia.
3. Blood gas analysis can maintain arterial partial pressure of oxygen greater than 8kPa (60mmHg) when inhaling low concentration oxygen (less than 50% oxygen).
Severe poisoning
Those with the following 1.2.3 or 4 items can be diagnosed as severe poisoning.
1. Severe cough, a large amount of pink foam sputum, shortness of breath, chest tightnesspalpitationAnd often has irritability, nausea, vomiting or coma;Respiratory distress, obvious cyanosis, lungs full of dry and wet rales.
2. Chest X-ray signs: the two lung fields have patchy and cloud like shadows with lighter density and blurred edges, which can be fused into large areas or butterfly shaped shadows, consistent with severe pneumonia or edema.
3. Blood gas analysis: under the condition of inhaling high concentration oxygen (more than 50%), the partial pressure of arterial blood oxygen is still lower than 8kPa (60mmHg).
4. The degree of damage to the respiratory system is consistent with moderate poisoning, accompanied by severe laryngeal edema or asphyxia caused by necrosis and abscission of bronchial mucosa;Or severe pneumothorax or mediastinal emphysema;Or obvious organ damage such as heart, liver or kidney.
conventional therapy
Announce
edit
1. Get out of the poisoning scene quickly and breathe fresh air or oxygen.Respiratory stimulants can be used as appropriate when breathing is shallow or slow.Those who have stopped breathing or heartbeat should be given cardiopulmonary resuscitation immediately.Don't give up easily.For laryngospasm and vocal cord edema, tracheal intubation or tracheotomy should be performed quickly.
2. Take off your clothes and thoroughly clean the skin in contact with ammonia with clean water or 1%~3% boric acid water.Rinse eyes with 1%~3% boric acid water, and then apply antibiotics and cortisone eye drops.
3. Intravenous drip of 10% glucose solution, calcium gluconate, adrenocortical hormone and antibiotics to prevent infection and laryngeal edema.
4. Aerosol inhalation of dexamethasone and antibiotic solution.
5. Comatose patients use 250ml 20% mannitol intravenously every 6-8 hours to reduce intracranial pressure.
Hyperbaric oxygen therapy
Announce
edit
1. Treatment principle Whether patients with ammonia poisoning can receive hyperbaric oxygen treatment has been debated.Some people worry that respiratory secretions or shedding may be pressed intoa bronchial tubeIn the alveoli, the airway is blocked and the infection is aggravated, so it is considered that hyperbaric oxygen therapy is not suitable for ammonia poisoning.The author believes that when the patient is in the dangerous stage of severe hypoxia, pulmonary edema, brain edema and shock, if the hypoxia is not corrected in time and the pulmonary edema, brain edema and shock are controlled, life will soon be endangered.At this time, only hyperbaric oxygen treatment can quickly correct hypoxia, control pulmonary edema and brain edema, break the vicious circle, and create conditions and gain enough time for body recovery.Principle of hyperbaric oxygen therapy:
(1) Rapid correction of tissue hypoxia: the damage of bronchi and alveoli caused by ammonia poisoning, pulmonary edema, and pulmonary ventilation and ventilation functions are impaired. The arterial partial pressure of oxygen (PaO2) can be lower than 8.0kPa (60mmHg) or even as low as 4kPa (30mmHg), causing severe hypoxia of the body.In this case, the arterial partial pressure of oxygen will not be higher than 8.0 ～ 9.3kPa (60 ～ 70mmHg) when nasal tube oxygen inhalation is used under normal pressure, while the arterial partial pressure of oxygen will easily increase to 13.3 ～ 26.6kPa (100 ～ 200mmHg) when breathing pure oxygen in a high-pressure environment.This can quickly correct the hypoxia state of the tissue.Improve tissue aerobic oxidation, increase energy supply, and correct tissue acidosis.
(2) Under high pressure, the volume of air bubbles in the respiratory tract shrinks or breaks, and the foam in the respiratory tract decreases to keep the respiratory tract unobstructed.
(3) Hyperbaric oxygen can reduce intracranial pressure and prevent brain edema.
(4) High pressure can prevent pulmonary edema.
(5) Hyperbaric oxygen can control shock.
(6) Hyperbaric oxygen can rapidly improve the hypoxia of various organs and accelerate the repair of various organs, such as heart, liver, kidney, brain, etc.
2. Treatment methods and precautions Due to the dangerous and critical condition of ammonia poisoning, the respiratory tract mucosa is severely damaged, the wound is deep, and the secretion and shedding may block the respiratory tract.Therefore:
(1) The treatment pressure should not be too high, 0.2 MPa is appropriate.The pressure rise time should be appropriately extended to 40~50 minutes to avoid severe pressure changes and blockage of respiratory tract by falling objects.The decompression time should also be extended by 40~50 minutes.The pressure stabilization time is unchanged, and the oxygen inhalation time cannot be extended at will.
(2) When hyperbaric oxygen treatment is performed, medical personnel should accompany the cabin for monitoring, and trachea intubation and tracheotomy articles should be prepared;Prepare sputum aspirator and large empty needle.Routine treatment should not be interrupted in the cabin.
(3) After the first hyperbaric oxygen treatment, if the hypoxia correction is unsatisfactory and the pulmonary edema and brain edema are not controlled, another hyperbaric oxygen treatment can be performed after the door hours.
