Paraquat Poisoning

Key Features

• Used as a herbicide; sale is controlled

Clinical Findings

• Concentrated solutions are highly corrosive to oropharynx, esophagus, and stomach

• After absorption, fatal dose may be as small as 4 mg/kg

• If ingestion of paraquat is not rapidly fatal because of its corrosive effects, the herbicide may cause progressive pulmonary fibrosis, with death ensuing after 2–3 weeks

Diagnosis

• Clinical

• Patients with plasma paraquat levels above 2 mg/L at 6 hours or 0.2 mg/L at 24 hours are likely to die

Treatment

• Administer 60 g of activated charcoal by gastric tube every 2 hours for at least three or four doses

• Anecdotal reports of benefit with cyclophosphamide and dexamethasone

• Supplemental oxygen should be withheld unless the PO₂ is < 70 mm Hg because oxygen may contribute to the pulmonary damage