Paraquat not only dries up the grass, it may also dries up your lungs

This is the 5103th article of Da Yi Xiao Hu

On July 30, 2024, the Australian Pesticides and Veterinary Medicines Authority (APVMA) re-evaluated paraquat and diquat, and both were not supported in 90% of the application scenarios in Australia. my country also revoked the registration and production license of paraquat aqueous solution and stopped production on July 1, 2014, but retained the registration of aqueous solution for export overseas by the parent drug manufacturer and allowed production exclusively for export. On July 1, 2016, the domestic sales and use of aqueous solution was stopped.

Why has paraquat, a colorless, odorless, and highly effective herbicide, been gradually eliminated from the world's mainstream stage in recent years? Because of its toxicity, which is still unavoidable!

The poison of paraquat is 1. It is extremely toxic to humans 2. There is no specific antidote, the death process is painful, and there is really no cure 3. The mortality rate of oral poisoning is extremely high, the legendary 99% mortality rate. Some people joked that out of ten people who drank paraquat, nine died, and the other one drank fake paraquat.

Generally speaking, if 5 to 10 ml of 20% paraquat concentrate is taken orally, it is almost 100% fatal if rescue is not timely. How much is 5 ml? It is just the amount of a mineral water bottle cap. Quoting the original words of a poisoned person, "It is like a drowning person. No matter how hard he tries, he can only watch himself sink to the bottom of the water. People in the late stage of paraquat poisoning gradually lose their breath while awake, and eventually suffocate to death. ... Drinking paraquat is like waiting to be buried alive. The mouth and throat have rotted and cannot speak, and the lungs can't breathe."

Paraquat treatment

At present, the rescue treatment of paraquat is only a remedy. There is no cure yet. Either the entry of poison is reduced, or the damage to organs throughout the body is slowed down.

1) Clean skin and oral residues

2) Fluid therapy, hemoperfusion

3) The respiratory tract is the most seriously affected, and pulmonary fibrosis is very likely to occur, leading to respiratory distress. Oxygen and mechanical ventilation should be used as soon as possible.

4) Digestive tract: Temporarily prohibit eating and drinking, place a gastric tube, perform gastrointestinal decompression, and use gastric mucosal protective agents to prevent stress ulcer bleeding.

5) Drugs: Propranolol can compete with the poisons bound to the lungs. High-dose cyclophosphamide and dexamethasone prevent pulmonary fibrosis. Desferrioxamine and N-acetylcysteine ​​therapy. There is no specific antidote.

6) Monitor liver and kidney function and blood oxygen levels.

Since paraquat poisoning can cause devastating damage to the lungs, is it possible to get a lung transplant?

Everyone is curious about whether there are successful lung transplants for patients with paraquat poisoning. Looking back at the clinical data of a paraquat poisoning lung transplant patient completed by Guangzhou Medical University in 2017, a 26-year-old female patient in her prime ingested 20ml of 20% paraquat solution when she was admitted to the hospital. On the 58th day of poisoning, she underwent a double lung transplant under general anesthesia. The lungs removed during the operation showed extensive pulmonary fibrosis in both lungs. Fortunately, the operation was successful. This was also due to the advancement of extracorporeal membrane oxygenation (ECMO) and blood purification technology.

After all, only a few people can undergo lung transplantation. When there is a shortage of lung organs, are there any other treatments?

Lung transplantation is the only effective treatment for end-stage lung disease, but the organ shortage crisis requires the development of alternative therapies. Mesenchymal stem cells (MSCs) and hepatocyte growth factor (HGF) have been shown to partially reverse this damage. Mesenchymal stem cells can be derived from bone marrow (BM-MSCs), adipose tissue (AD-MSCs), umbilical cord (UC-MSCs), dental pulp (DPSCs) and other sources. This type of research has mainly seen the dawn of hope in rat experiments: human amniotic mesenchymal stem cells (hAMSCs) have a therapeutic effect on paraquat (PQ)-induced rat pulmonary fibrosis. There are also studies suggesting that immature fetal lung tissue can improve the survival rate of mice with severe lung injury caused by PQ, and anti-inflammatory cytokines in fetal mouse lung tissue on embryonic day 13.5 may inhibit severe lung injury. Although these experiments have not yet been applied to clinical practice, they are already a very promising future treatment direction for pulmonary fibrosis caused by PQ poisoning.

Author: Putuo District Central Hospital

Department of Respiratory Medicine Shi Zhaowen, deputy chief physician