Paraquat poisoning

　　Paraquat is rapidly absorbed after oral intake, mainly accumulated in the lungs and muscles, excreted slowly, and therefore its toxic effects can persist. Lesions mainly occur in the lungs, known as paraquat lung (paraquet lung). Besides herbicides, which can produce peroxide ions (O-2) to damage type I and II alveolar epithelial cells, causing swelling, degeneration, and necrosis, and inhibiting the production of pulmonary surfactant substances. The basic lesions are proliferative bronchiolitis and alveolitis. The morphological changes of the lung depend on the duration of survival after intake. Those who die within one week show lung congestion, edema, increased lung weight, similar to oxygen poisoning. Those with a survival period exceeding one week have alveolar exudates (containing fallen alveolar epithelial fragments, macrophages, red blood cells, and hyaline membranes) organization, mononuclear cell infiltration, hemorrhage, and interstitial fibroblast proliferation, thickening of alveolar interstitium, resulting in widespread fibrosis, forming honeycomb lungs and bronchiectasis. Paraquat poisoning can cause renal tubular necrosis, central liver lobule cell damage, necrosis, myocarditis, thickening of the middle layer of pulmonary arteries, adrenal cortex necrosis, and other complications.

　　The lethal dose of oral intake is about 14mg/kg, and the mortality rate of severe poisoning can reach 60%-80%, with survivors often suffering from severe pulmonary fibrosis.

　　1. Skin contamination can lead to contact dermatitis, even causing burn-like damage, manifested as erythema, blisters, ulcers, and necrosis. Nails can also be severely damaged or fall off. Oral poisoning may also cause erythema.

　　2, Eye contamination may cause symptoms such as blushing, tears, eye pain, conjunctival congestion, and corneal burns.

　　3, Inhalation of respiratory tract may cause nosebleeds and symptoms of nasal and pharyngeal irritation (such as sneezing, sore throat, congestion, etc.) and irritating cough.

　　4, Ingestion by mouth may cause corrosion and ulceration of the oral mucosa, pharynx, and esophagus.

　　Ingestion of herbicides can cause burning sensation in the tongue, mouth, and throat, leading to esophagitis and gastritis, causing vomiting and abdominal pain. The excretion of drugs through the kidneys can damage the renal tubules, producing proteinuria, hematuria, increased blood urea nitrogen, creatinine, and other manifestations of renal dysfunction. The respiratory system is mainly manifested as progressive respiratory difficulty and cyanosis, ultimately leading to respiratory failure and death. Chest X-ray findings: Initially, scattered fine dot-like shadows, more in the lower lung fields, rapidly progressing, lesions融合 into severe pulmonary edema-like morphology. Pulmonary function is mainly manifested as carbon monoxide diffusion impairment, moderate airway obstruction and (or) restrictive ventilation abnormalities.中毒 of the heart, liver, and adrenal glands can cause corresponding symptoms and signs.

　　The herbicidal effect of paraquat was discovered at the end of the 1950s, and it was first sold on the market in 1962. Currently, paraquat is the second largest herbicide in the world herbicide market and has been registered and used in more than 100 countries.

　　Paraquat is a rapid-acting contact herbicide that can take effect quickly after spraying and quickly deactivate after contacting the soil. There is no residue in the soil. Normal use has no harm to wild animals and the environment. Proper use has no adverse effects on the health of the workers involved in spraying.

　　Paraquat is widely used on a variety of crops in both developed and developing countries, promoting the increase of agricultural productivity.

　　The use of this herbicide can reduce agricultural operations, help prevent soil erosion, maintain soil humidity, and promote the development of 'no-till agriculture' or 'direct seeding agriculture' that does not consume time and energy.

　　1, Laboratory examination:Peripheral blood white blood cell count significantly increased; paraquat can be detected in blood and urine; the difference between alveolar/arterial PaO2 increases, and severe hypoxemia occurs.

　　2, Pulmonary X-ray examination:Early stage of poisoning (3 days to 1 week), mainly characterized by increased pulmonary markings, interstitial inflammatory changes, visible dots, patchy shadows, reduced pulmonary translucency or glassy appearance; in the middle stage (1-2 weeks), pulmonary consolidation or extensive consolidation appears, accompanied by partial pulmonary fibrosis; in the late stage (after 2 weeks), pulmonary fibrosis and atelectasis occur.

　　Food therapy recipe:(For reference only, please consult a doctor for specific information)

　　1, Salt解毒 (folk recipe)

　　Indications: Food poisoning.

　　Formula: 60 grams of salt.

　　Usage: Roast salt until it turns yellow, dissolve it in boiling water for internal use to induce vomiting; or use 1 tablespoon of salt, roast it and then decoct the soup for drinking. Alternatively, drink a large amount of saltwater at a concentration of 0.5%, and then stimulate the throat with a finger or feather to promote vomiting.

　　2, Ginger Soup (folk recipe)

　　Indications: Poisoning.

　　Formula: Appropriate amount of ginger.

　　Usage: Take ginger decoction alone, which can relieve fish and crab poisoning. Or add a few slices of ginger when cooking fish and crab to prevent poisoning.

　　3, Huangluo Dan (folk recipe)

　　Indications: Detoxification for general poisoning.

　　Formula: 250 grams of soybeans and mung beans each.

　　Usage: Grind into powder, add water to one bowl, stir evenly and clarify the clear liquid for drinking.

　　First, emergency measures:

　　1, Thoroughly lavage the stomach as soon as possible to accelerate excretion.There is currently no effective antidote for paraquat poisoning. In view of the fact that the absorption rate of paraquat in the gastrointestinal tract is only 5% to 15%, and it is stable in acidic and neutral environments, it can be hydrolyzed in alkaline solutions. Therefore, during rescue, alkaline liquids should be used as soon as possible to thoroughly lavage the stomach, such as using activated carbon and citric acid for lavage. To accelerate excretion, magnesium sulfate, glycerol, rhubarb, and other substances can be used.

　　2, Apply lung-protecting drugs as soon as possible.The mechanism of paraquat poisoning is mainly the production of oxygen free radicals in the lungs, which destroy lung cells, leading to pulmonary fibrosis and respiratory failure. Therefore, superoxide dismutase (SOD), paraquat monoclonal antibody, high-dose vitamin C and E should be used as soon as possible to prevent the excessive and rapid formation of oxygen free radicals and reduce their damage to cell membrane structure.

　　3, Use a respirator as soon as possible.To increase gas exchange, improve oxygenation function, increase oxygen partial pressure, and reduce lung injury.

　　4, Perform hemoperfusion as soon as possible.Experience has shown that patients who have not been infused and whose survival time exceeds 48 hours have all suffered from serious damage to the lungs, liver, and stomach, and ultimately died of multiple organ failure.

　　Second, the method of traditional Chinese medicine for paraquat poisoning

　　Traditional Chinese medicine treatment:

　　1, Curcumin extract

　　The effect of baicalin on the expression of heme oxygenase-1 in lung tissue of rats with acute lung injury caused by paraquat poisoning.

　　2, Ginkgo biloba extract

　　Experiments show that PQ has a serious damaging effect on PC12 cells, while ginkgo biloba extract can significantly reduce the cytotoxicity of PQ on PC12 cells, enhance cell activity, reduce the percentage of apoptosis, reduce the number of apoptosis, and inhibit the decrease of mitochondrial membrane potential. It has a protective effect on apoptosis induced by PQ in PC12 cells, and its mechanism may be related to the inhibition of the decrease of mitochondrial membrane potential caused by PQ.

　　3, Hypericum perforatum extract

　　Hypericum perforatum extract is a complex mixture composed of various components, which have the effect of antioxidant against lipid peroxidation. Animal experiments have confirmed that hypericum perforatum extract can induce antioxidant effects by altering the levels and activities of malondialdehyde, glutathione peroxidase and/or glutathione in the body. At the same time, Jang et al. analyzed whether hypericum perforatum extract has antioxidant activity against H2O2. The results show that cells treated with H2O2 exhibit many apoptosis characteristics, while the apoptosis characteristics of cells treated with hypericum perforatum extract before H2O2 treatment are reduced. The research results of Wei Wei et al. indicate that hypericum perforatum extract can reduce the degree of lipid peroxidation of cell membranes in patients with paraquat poisoning, reduce the generation of MDA, and alleviate the tissue damage caused by paraquat.

　　4, Treatment with extracts of Angelica sinensis and Ligusticum chuanxiong

　　Sodium ferulate is the sodium salt of ferulic acid extracted from Chinese herb Angelica sinensis and Ligusticum chuanxiong. Wang Zehui and others' experiments show that SF拮抗ET effect at the receptor level and can reduce ET levels in plasma and lung tissue. Its phenylpropene structure can antagonize vasoconstriction caused by endothelin and can increase NO synthesis, reduce pulmonary artery pressure, dilate airways, and the injury of lung tissue is significantly reduced compared to the poisoning group, indicating that the effect of SF is significant. The experiment also shows that the content of tumor necrosis factor is significantly reduced after SF treatment, indicating that SF has a significant inhibitory effect on TNF-α.

　　Third, Western medical treatment methods for paraquat poisoning

　　1, General treatment

　　(1) Skin contact poisoning: Immediately remove contaminated clothing, thoroughly wash with soap water, if the eyes are contaminated, use 2%-4% sodium bicarbonate solution for irrigation.

　　(2) Oral poisoning:

　　①Induce vomiting: Once diagnosed, stimulate the throat to induce vomiting, take adsorbents or clay as soon as possible.

　　②Immediate gastric lavage: Use 30% kaolin water or 1% soap water or mud water mixed with activated carbon 50-100g for repeated gastric lavage, as thorough as possible.

　　③Laxative: After gastric lavage, use activated carbon suspension (50g) + magnesium sulfate (20-40g) for laxative; or use 50ml of Ringer's solution + magnesium sulfate (20-40g); or oral Fushong 20g; or 20% bleaching earth (Simida) suspension 300ml, activated carbon 60g/20% mannitol 100-150ml, magnesium sulfate 15g, used alternately every 2-3 hours, lasting for 3-7 days.

　　④Accelerate the excretion of toxic substances: diuresis, hemodialysis, hemoperfusion, the latter has better effects.

　　2, Drug treatment

　　(1) Antioxidant free radical treatment: Vitamin E, vitamin C, vitamin B1, niacin, and superoxide dismutase can destroy oxygen free radicals.

　　(2) Prevention and treatment of pulmonary fibrosis and anti-pulmonary fibrinolysis:

　　Traditional treatment plan

　　①A Propranolol (propranolol) should be used early, competing with receptors bound in the lungs, 10mg, tid.

　　②B Glucocorticoids: The administration time is determined according to the condition, generally can be used for 10-14 days

　　③Methylprednisolone injection: 40-80mg, q8h, iv;

　　④Dexamethasone injection: 7.5mg, q8h, iv;

　　⑤Hydrocortisone injection: 200mg, q8h, iv;

　　⑥C Immunosuppressant: Cyclophosphamide 5mg/kgd (total dose 4g), colchicine 0.5mg, bid

　　⑦Foreign reports on cyclophosphamide and corticosteroid hormone therapy: Cyclophosphamide (5mg/kgd, total dose 4g) and dexamethasone (8mg, 3 times a day, for 2 weeks) treatment, survival rate reached 72%.

　　⑧Xuèbìjìng treatment: 100ml of Xuèbìjìng injection, twice to four times a day.

　　⑨Improve microcirculation: Compound Danshen injection (30-40mg/d), scopolamine (2.4-10mg/d), and dexamethasone (25mg/d) can effectively remove oxygen free radicals, maintain organ function, and reduce mortality.

　　⑩ Desferrioxamine (100mg/kg.24) and acetylcysteine (300mg/kg.d)

　　3. Blood purification therapy

　　Hemoperfusion, as a blood purification method, is widely used in the field of poisoning, and its principle is that the adsorbent removes toxins through physical adsorption, and is the first-aid method of choice for rescuing patients in clinical practice. The amount of toxic substances in the tissue is determined by the blood concentration in the early stage of poisoning, so hemoperfusion should be carried out within 6 hours, and the first treatment can be continuous for 2-3 days. Whether to use hemoperfusion for paraquat poisoning patients should consider the following factors:

　　a. Ingesting a near-lethal dose of paraquat, or having a survival hope of 20-70%, means that within a few hours after ingestion, the use of hemoperfusion is very helpful for the recovery of the disease.

　　b. The amount ingested exceeds many times the lethal dose, or the prognosis is poor. In this case, the use of hemoperfusion is less helpful for the recovery of the disease, but it can still be tried if there is an opportunity, and the patient still has a chance to survive.

　　c. Continuous application of hemoperfusion has no effect on saving lives, but can extend the survival period, allowing more time to choose other treatment methods, such as lung transplantation.

　　4. Lung transplantation

　　The chance of successful lung transplantation in the early stage is very small, and the chance of successful lung transplantation in the later stage is relatively high, but there is no obvious division between the early and late stages of the disease process, and lung transplantation requires certain conditions, technical strength, and economic burden, and there has been no clinical report in China.

　　Four, Prognosis:

　　1. A clear history of ingestion, meaning that paraquat has been clearly ingested.

　　2. Oral poisoning may cause oral and esophageal ulcers, nausea, vomiting, abdominal pain, diarrhea, hematochezia, and some patients may develop toxic hepatitis.

　　3. Respiratory system damage may manifest as cough, sputum, difficulty breathing, with a few patients developing pulmonary edema. Severe cases may die due to adult respiratory distress syndrome. The drug has a strong ability to cause pulmonary fibrosis, and some patients may continue to develop pulmonary lesions after the acute poisoning symptoms are controlled. Pulmonary fibrosis often occurs between the 5th and 9th day, reaching a peak in 2 to 3 weeks. Ultimately, death may occur due to pulmonary fibrosis and respiratory failure.

　　4. Central nervous system disorders may manifest as headaches, dizziness, convulsions, hallucinations, and so on.

　　5. A few severe patients may suffer from myocardial damage and acute renal failure.

　　6. The drug is irritating and can cause contact dermatitis, conjunctival and corneal burns.