Author: Guo Zhongzhou, Department of Pharmacy, Pearl River Hospital, Southern Medical University
#The situation of 13-year-old girls who drink paraquat has deteriorated# According to the "Big Reference" column of The People's Livelihood Channel of Henan Radio and Television Station, on October 5, the "13-year-old girl drinking paraquat" in Zhengzhou, Henan Province, has aroused everyone's attention in recent days, and the girl's physical health status has also touched the hearts of many netizens. At two o'clock in the morning today (October 5), the girl's condition suddenly deteriorated, and the family could not cry about this situation, "The kidneys were normal in all aspects of the first three days, and the attack began on the fourth day!" The lungs change every hour! ”
<h1 class="pgc-h-arrow-right" data-track="9" > paraquat introduction</h1>
Paraquat (PQ), also known as gramoxone, is a highly effective non-selective contact herbicide used worldwide, synthesized in 1882, produced as an agricultural herbicide in 1962, and entered China in 1984. After PQ spraying, it quickly takes effect and enters the soil and is rapidly inactivated, which has a strong toxic effect on humans and animals. Acute PQ poisoning (acute paraquat poisoning) refers to the prominent manifestation of progressive diffuse pulmonary fibrosis after oral administration, and eventually dies of respiratory failure and/or MODS (Note: multi-organ dysfunction syndrome), with a case fatality rate of up to 90% to 100%.
PQ has two kinds of dichloride and methyl disulfate salt, pure white crystal, easily soluble in water, stable in acid or neutral solution. Most of the blue solutions sold in China are 20%. There is no specific antidote to the product, and more than 20 countries, including Europe and the United States, have banned or severely restricted the use of paraquat. In April 2012, The Ministry of Agriculture of China issued Announcement No. 1745, which revoked the registration and production license of PQ water agent from July 1, 2014, and completely stopped the sales and use of PQ water agent in China from July 1, 2016.
<h1 class="pgc-h-arrow-right" data-track="74" > etiology and pathogenesis</h1>
Acute paraquat poisoning is often oral suicide or accidental poisoning. The lethal oral dose for adults is 2-6 g. It can also be absorbed by skin, respiratory tract and poisoned by intravenous injection.
Corrosive damage occurs at the site of oral PQ contact, which is rapidly distributed to tissues and organs throughout the body after absorption, and the blood concentration reaches a peak in 0.5-4 hours, rarely binding to plasma proteins. Concentrations of lung tissue (10 or dozens of times that of blood) and skeletal muscle are highest. PQ is rarely degraded in the human body, 50% to 70% is excreted through the kidney in its original form at 24 hours, about 30% is excreted with feces, and can also be excreted through breast milk. Experiments have found that 6 hours after intravenous injection of PQ, 80% to 90% are excreted through the kidneys, and almost completely discharged after 24 hours. PQ can also cause brain damage through the blood-brain barrier.
The mechanism of PQ poisoning is not fully understood, mainly involved in the redox reaction of cells in vivo, forming a large number of reactive oxygen radicals and peroxide ions, causing lipid peroxidation of tissue cell membranes, resulting in MODS or death. Peroxide ions damage the alveolar epithelium of type I and type II, and the production of pulmonary surfactant is reduced. Due to the active uptake and accumulation of PQ by lung tissue, the damage is severely damaged, and the patient gradually develops irreversible pulmonary fibrosis and respiratory failure within 4 to 15 days, and eventually dies of refractory hypoxemia. Some people call it a PQ lung (pa-raquat lung).
<h1 class="pgc-h-arrow-right" data-track="75" > pathology</h1>
The basic pathological changes of the PQ lung are proliferative bronchiolitis and alveolitis. In those who die within 1 week, alveolar cells are hyperemia, swelling, degeneration and necrosis, alveolar septal rupture and fusion, pulmonary edema, hyaline membrane formation, and increased lung weight; in patients who die more than 1 week, pulmonary stromal cell hyperplasia, lung interstitial thickening and pulmonary fibrosis occur. Pulmonary fibrosis occurs 5 to 9 days after poisoning and peaks at 2 to 3 weeks. Necrosis of tubules, central lobular cells of the liver, myocarditis and adrenal cortex necrosis may also be seen.
<h1 class="pgc-h-arrow-right" data-track="76" > clinical manifestations</h1>
The performance of poisoned patients is related to the route, amount, speed and basic health of the body of the poison.
(i) Local injury
Delayed onset of erythema, blisters, erosions, ulcers, and necrosis on the skin at the site of contact. Oral poisoning, oral and esophageal mucosa burns and ulceration. When poisons contaminate the eye, they can burn the conjunctiva or cornea. Nasal bleeding may occur in inhalers.
(ii) System damage
1. Respiratory system After swallowing PQ, the lungs are mainly damaged, and cough, shortness of breath (which can be caused by metabolic acidosis, aspiration or acute alveolitis) and pulmonary edema gradually occur within 2-4 days, and mediastinal emphysema and pneumothorax can also occur. People with lung injury die more than 2 to 3 weeks from respiratory failure due to diffuse pulmonary fibrosis. A large number of oral patients develop pulmonary edema and pulmonary hemorrhage within 24 hours, die of ARDS (Note: acute respiratory distress syndrome) within a few days, and rapidly appear cyanosis and coma after poisoning, and death is faster.
2. Digestive system After taking poisoning, post-sternal burning sensation, nausea, vomiting, abdominal pain, diarrhea, gastrointestinal perforation and bleeding. Liver damage and liver necrosis occur within 1 to 3 days.
3. Other symptoms of palpitations, chest tightness, shortness of breath, toxic myocarditis, dizziness, headache, convulsions or coma, renal damage occurs 24 hours after PQ absorption, manifested as hematuria, proteinuria or acute renal failure; hemolytic anemia or DIC, shock can also occur. People with MODS often die within days.
(3) Clinical classification
According to the amount of poison taken, it is divided into: (1) mild: intake < 20mg/kg, in addition to gastrointestinal symptoms, other symptoms are not obvious, most patients can fully recover; (2) medium and severe: intake of 20-40mg/kg, in addition to gastrointestinal symptoms can appear multi-system involvement, 1-4 days of renal function, liver function damage, a few days to 2 weeks of lung injury, mostly in 2-3 weeks to die of respiratory failure; (3) outbreak type: intake of > 40mg / kg, there are severe gastrointestinal symptoms, 1 ~ 4 days to die of MOF (Note: multiple organ failure)
<h1 class="pgc-h-arrow-right" data-track="80" > treatment</h1>
At present, there is no specific antidote to PQ poisoning patients! There is no specific antidote yet! There is no specific antidote yet!
(i) Recovery
1. Keep the airway open
Monitor oxygen saturation or arterial blood gases. Mild to moderate hypoxemia should not be routinely oxygenated, oxygen inhalation will accelerate the formation of oxygen free radicals, enhance PQ toxicity, increase mortality rate. PaO, < 40 mmHg or in the presence of ARDS, can inhale oxygen concentrations of more than 21%, maintain PaO, > 70 mmHg. In patients with severe respiratory failure, mechanical ventilation therapy is not ideal.
2. Hypotension
Volume depletion is often often preceded by rapid intravenous fluids to restore effective volume.
3. Organ function support
In patients with upper GASTRO bleeding, proton pump inhibitors such as omeprazole, lansoprazole, or pantoprazole are used; hemodialysis may be considered in patients with symptomatic acute renal failure.
(2) Reduce the absorption of poisons
1, remove the toxic pollution Immediately remove the PQ contaminated clothing, rinse the contaminated skin with soapy water; oral, rinse with compound borax mouthwash or chlorhexidine (chlorhexidine) gargle; eye polluters, rinse with 2%-4% sodium bicarbonate solution for 15 minutes, and then rinse with normal saline.
2. Inducing vomiting and gastric lavage Oral poisoning, immediately stimulate the throat to induce vomiting; use water or alkaline liquid (such as soapy water) to fully wash the stomach; within 1 hour of taking poison, use 15% white clay solution (adult 1000ml, children 15ml/kg) or activated charcoal (100g, children 2g/kg) adsorption gastric lavage. Gastric motility drugs (domperidone, moszapride) can be given after gastric lavage to promote excretion.
3. Diarrhea after gastric lavage, give 20% mannitol, magnesium sulfate, sodium sulfate, senna leaf (10 ~ 15g plus 200ml of boiling water soaked in cool clothes) or rhubarb diarrhea.
(3) Increase the discharge of poisons
1. Strengthen diuresis After active and adequate intravenous fluid, furosemide should be used to maintain urine output of 200ml/h
2. Blood purification should be carried out as soon as possible (within 2-4 hours), first select blood perfusion, and its PQ clearance rate is 5 to 7 times that of hemodialysis.
(4) Other treatments
1. Immunosuppressive drugs Early intravenous application of high-dose methylprednisolone, dexamethasone and/or cyclophosphamide
2. Antioxidants (antioxidants) such as the application of high-dose vitamin C or E, superoxide dis mutase (SOD), acetylcysteine (NAC), reduced glutathione, ulinastatin or edaravone. High doses of ambroxol also directly scavenge free radicals in the body, reduce the effect of paraquat in acute lung injury, and promote the production of alveolar surfactant.
3. Anti-fibrosis drug pirfenidone inhibits the biological activity and collagen synthesis of fibroblasts, prevents and reverses fibrosis and scarring.
4. PQ competitor propranolol (10 to 20 mg orally, 3 times / day) can promote the release of PQ bound to lung tissue. Low-dose levodopa can competitively inhibit PQ through the blood-brain barrier.
(5) Traditional Chinese medicine treatment
Perforatum extract has an anti-lipid peroxidation effect. Angelica and Sichuan root extracts can increase NO synthesis, reduce pulmonary artery pressure, and reduce lung tissue damage. Hebijing has the effect of inhibiting the activity of some inflammatory factors and alleviating the damage of poisoned organs.
<h1 class="pgc-h-arrow-right" data-track="84" > prevention</h1>
Prevention is better than cure. PQ should be centrally managed and used, private storage is strictly prohibited; the medicinal liquid utensils containing PQ should have warning signs to prevent accidental taking; safety protection education should be carried out before use, and long clothes and trousers and protective glasses should be worn when using, and the skin should not be exposed and sprayed against the wind.
<h1 class="pgc-h-arrow-right" data-track="85" > Xiaobian's message:</h1>
Life is precious, and life is the most expensive. Whatever it is, life cannot be thrown away.
The above is the original work of the volunteers of the "Drug Safety Cooperation Alliance", if you reprint, please indicate the author and source!
【Medicine Shield Public Welfare】PSM Pharmaceutical Shield Public Welfare (public number: PSMChina), a public welfare organization jointly initiated and established by the China Over-the-Counter Drug Association, the Chinese Pharmaceutical Association, etc., gathers resources, gathers strength, and promotes the safety of public medication.
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