What is the treatment for paraquat poisoning?

Treatment for Paraquat Poisoning

Paraquat poisoning requires immediate aggressive decontamination with multiple-dose activated charcoal, strict oxygen restriction (target SpO2 85-88%), and supportive care, though prognosis remains poor even with optimal treatment. 1, 2

Immediate Safety and Decontamination

Rescuer Protection

• Wear protective clothing and gloves when handling the victim, contaminated clothing, or body fluids (especially vomit) to prevent secondary exposure 1
• Contact poison control centers immediately for expert guidance 1, 2

Skin Decontamination (First Priority)

• Remove all contaminated clothing immediately 1, 2
• Thoroughly wash all exposed skin areas with soap and water to prevent continued dermal absorption 1, 2
• In pediatric patients, use warmed shower water at lower pressure with heat lamps and blankets to prevent hypothermia 2

Gastrointestinal Decontamination

• Do NOT perform routine gastric lavage - activated charcoal is the evidence-based alternative 2
• Administer multiple-dose activated charcoal (15-20g every 6 hours) ONLY after airway protection and hemodynamic stabilization 1, 2
• Never attempt decontamination before securing the airway due to significant aspiration risk 2

Critical Oxygen Management (Unique to Paraquat)

This is the most critical pitfall to avoid - liberal oxygen is uniquely harmful in paraquat poisoning:

• Avoid supplemental oxygen unless SpO2 falls below 85% 1, 2
• Target oxygen saturation of 85-88% - do not exceed this range 1, 2
• Reduce or stop oxygen therapy if saturation rises above 88% 1, 2
• High oxygen concentrations dramatically worsen paraquat toxicity by increasing free radical production and accelerating lung injury 1, 2

Supportive Care

Airway and Hemodynamic Management

• Ensure airway protection as first priority before any decontamination 1, 2
• Provide hemodynamic support and correct metabolic derangements 1
• Treat seizures or agitation with benzodiazepines if they occur 3

Extracorporeal Treatment Considerations

• Hemodialysis and hemoperfusion have been attempted but evidence for efficacy is limited 4, 5, 6
• One case report suggests early hemodialysis combined with antioxidant therapy (deferoxamine 100 mg/kg/24h and acetylcysteine 300 mg/kg/day for 3 weeks) may limit systemic toxicity 5
• However, neither hemofiltration nor immunosuppressive therapies have been shown to improve survival in larger case series 6

Antioxidant Therapy

• Consider N-acetylcysteine or S-carboxymethylcysteine as antioxidants, though evidence is limited to case reports and small series 5, 7
• One series of 35 patients using S-carboxymethylcysteine 1500 mg for 2-3 weeks showed 22.86% mortality, though this was related to poisoning severity 7

Prognostic Indicators

Poor prognostic factors include:

• Positive urine paraquat test (47.4% mortality vs 15.2% with negative test) 6
• Intentional exposure 6
• Delay from exposure to hospital admission 6
• Manifestation of respiratory failure 6
• Ingestion of above-lethal doses despite optimal treatment 4

Key Clinical Pitfalls to Avoid

• Do not provide liberal supplemental oxygen - this is uniquely harmful and accelerates lung injury 1, 2
• Do not delay airway protection to perform gastrointestinal decontamination 2
• Do not use gastric lavage routinely when activated charcoal is the preferred method 2
• Do not expect survival even with aggressive multimodal therapy - prognosis remains uniformly poor and prevention is the utmost priority 8, 4

Expected Complications

• Acute respiratory distress syndrome and progressive pulmonary fibrosis with refractory hypoxemia 5
• Acute renal failure (may occur before ARDS) 4
• Hepatic injury 5
• Gastrointestinal caustic lesions and shock 5
• Long-term survivors are rare and typically have persistent GI and pulmonary complications 8