Paraquat Poisoning: What the Acute Care Physician Needs to Know?

Paraquat poisoning is one of the most common lethal poisonings in Isfahan, the central province of Iran. Due to the lower price and widespread usage of this potent herbicide for agricultural purposes, this kind of intoxication occurs almost frequently in this region. Paraquat is available here as a concentrated liquid, aerosol form or water soluble granules with different brand names. The toxicity of this poison is due to the creation of superoxide radicals through the electron transport system involved in intracellular conversion of NADPH to NAD. Superoxide anions and other free radicals are very toxic for the cell membrane. Paraquat poisoning affects the respiratory, cardiovascular, central nervous, endocrine, digestive, skin and almost all body systems, depending on the amount of ingestion. Toxic signs and symptoms of its poisoning would be appeared with the ingestion of at least 20 mg/kg or more in adults. Serum levels of 0.2 µg/ml 24 hours and 0.1 µg/ml 48 hours after ingestion, is usually associated with a fatal outcome. Immediate treatment is important for survival of patients. Supportive care, prevention of absorption of ingested poison, elimination measures and administration of antioxidants are all considered as the cornerstone of its treatment. There is no specific antidote for this toxin. High mortality rate of up to 75% in paraquat poisoning may be related to the amount of ingested toxin and the quality of medical care. Therefore, acute care physicians are supposed to have enough knowledge and skills for the supportive care and treatment of paraquat poisoning.