What is the treatment for paraquat poisoning?

Treatment for Paraquat Poisoning

The treatment for paraquat poisoning requires immediate decontamination, restricted oxygen therapy (targeting 85-88% saturation), early hemoperfusion within 2-4 hours of ingestion, and consideration of immunosuppressive and antioxidant therapies including cyclophosphamide, methylprednisolone, and N-acetylcysteine. 1

Immediate Management

Decontamination

• Remove all contaminated clothing immediately
• Perform thorough skin decontamination with soap and water
• Healthcare providers must wear appropriate protective equipment (gloves) to prevent secondary exposure 1
• Administer activated charcoal or Fuller's earth orally to minimize absorption 1, 2
• Gastric lavage should NOT be performed as it may increase absorption and cause additional injury 2

Critical Oxygen Management

• RESTRICT supplemental oxygen to target saturation of 85-88% 1
• Provide oxygen only when saturation falls below 85% 1
• Excessive oxygen worsens lung injury through enhanced free radical production 1
• This counterintuitive approach is essential as paraquat toxicity is potentiated by high oxygen concentrations 1

Extracorporeal Elimination

• Hemoperfusion with activated charcoal should be initiated within 2-4 hours of ingestion 1
• Standard hemodialysis is less effective but may be considered if hemoperfusion is unavailable 2
• These methods are most effective when started early but may have limited impact on overall survival 2

Pharmacological Interventions

Immunosuppressive Therapy

• Consider cyclophosphamide and methylprednisolone pulse therapy to reduce inflammation 1
• These medications may help prevent progressive pulmonary fibrosis, though evidence is limited 1, 2

Antioxidant Therapy

• N-acetylcysteine (300 mg/kg/day for up to 3 weeks) is recommended to reduce oxidative stress 1, 3
• Deferoxamine may be considered as an additional antioxidant (100 mg/kg in 24h) 3
• These agents target the free radical generation that is central to paraquat's toxicity mechanism 4, 2

Organ Support

Respiratory Management

• Avoid mechanical ventilation with high oxygen concentrations when possible 1
• If intubation is necessary for airway protection, use the lowest possible FiO2 1
• Monitor for progressive pulmonary fibrosis, which is often the ultimate cause of death 4

Renal Support

• Manage renal failure with appropriate fluid management 1
• Monitor for non-oliguric renal failure, which is common 3
• Initiate dialysis if needed for renal support (distinct from detoxification purposes) 1

Prognostic Indicators

• Plasma paraquat concentrations are the most important prognostic indicator 4, 2
• Urine and plasma dithionite tests provide guidance on severity 2
• Absence of caustic burns in the upper digestive tract indicates better prognosis 4
• Ingestion of >50 mg/kg typically results in death within 2 days 4

Important Caveats

• Despite all interventions, paraquat poisoning carries an extremely high mortality rate (up to 95%) 5
• Consult with a regional poison center or toxicologist immediately (US: 1-800-222-1222) 1
• Early recognition and intervention are critical for any chance of survival 1
• The primary mechanism of toxicity is generation of reactive oxygen species causing cellular damage through lipid peroxidation and mitochondrial damage 2
• Paraquat actively accumulates in lung tissue, leading to pneumonitis and pulmonary fibrosis 2