What is the treatment for paraquat poisoning?

Treatment of Paraquat Poisoning

Paraquat poisoning requires immediate decontamination with activated charcoal or Fuller's earth (not routine gastric lavage), strict oxygen restriction targeting SpO2 85-88%, and aggressive supportive care, as there is no effective antidote and mortality remains extremely high despite all interventions. 1, 2

Immediate Rescuer and Patient Safety

• Ensure rescuer safety first by wearing protective clothing and gloves when handling the patient, contaminated clothing, or body fluids (especially vomit), as paraquat can cause secondary exposure through skin contact. 2, 3
• Remove all contaminated clothing immediately and thoroughly wash all exposed skin areas with soap and water to prevent continued dermal absorption. 1, 2, 3
• Contact poison control centers immediately for expert guidance and maintain continuous contact for evolving treatment recommendations. 1, 2, 3

Gastrointestinal Decontamination

• Administer multiple-dose activated charcoal (15-20g every 6 hours) or Fuller's earth as the preferred decontamination method, but only after securing the airway and achieving hemodynamic stability. 1, 2, 4
• Do NOT perform routine gastric lavage, as the American College of Medical Toxicology recommends against this practice in favor of activated charcoal. 1, 4
• Gastric lavage should only be considered in the earliest phases after massive ingestion, but activated charcoal remains the evidence-based standard. 1, 5
• Never attempt decontamination before securing the airway, as aspiration risk is significant and potentially fatal. 1

Critical Oxygen Management (Unique to Paraquat)

• Avoid supplemental oxygen unless SpO2 falls below 85%, and reduce or stop oxygen therapy if saturation rises above 88%. 1, 2, 3
• Target oxygen saturation of 85-88%, which is dramatically lower than typical critical care targets. 1, 2, 3
• This restrictive oxygen strategy is critical because oxygen accelerates paraquat-induced lung injury by increasing free radical production and worsening pulmonary fibrosis. 1, 2, 3
• This represents a major pitfall: liberal oxygen administration, which is standard in most poisonings, is uniquely harmful in paraquat toxicity. 1, 3

Extracorporeal Elimination

• Hemodialysis or hemoperfusion may be attempted in severe cases, though evidence for improved survival is weak since paraquat rapidly distributes into tissues within 12-24 hours. 5, 6, 4
• Daily conventional hemodialysis for 10-14 days has been reported in case series with some favorable outcomes when combined with other therapies. 5
• Elimination methods are unlikely to significantly change clinical course once tissue distribution has occurred, but may be considered in the first 24 hours after massive ingestion. 6, 4

Immunosuppression and Antioxidant Therapy

• Immunosuppression with cyclophosphamide, methylprednisolone, and dexamethasone is widely practiced to prevent pulmonary fibrosis, though evidence for efficacy remains very weak. 5, 4
• Antioxidant therapy with N-acetylcysteine (300 mg/kg/day continuous infusion for 3 weeks) and deferoxamine (100 mg/kg in 24 hours) has been reported in survival cases and may limit systemic toxicity through free radical scavenging. 7, 4
• Despite theoretical benefits, no randomized controlled trials demonstrate clear survival benefit from these interventions. 4

Supportive Care

• Provide standard airway management if respiratory distress develops, with mechanical ventilation as needed while maintaining restrictive oxygen targets. 2, 3
• Treat hypotension with fluid resuscitation and vasopressors according to standard protocols. 2, 3
• Monitor and treat acute renal failure, which develops in the majority of patients who eventually die, though its presence alone does not necessarily indicate fatal outcome. 6, 4
• Administer benzodiazepines for seizures or severe agitation if they occur. 3

Prognostic Indicators

• Plasma paraquat concentration is the most important prognostic indicator, with ingestion of >50 mg/kg typically fatal within 2 days. 6, 4
• Absence of caustic burns in the upper digestive tract indicates better prognosis. 6
• Urine and plasma dithionite tests combined with clinical features provide good prognostic guidance. 4

Common Pitfalls to Avoid

• Do not delay airway protection to perform gastrointestinal decontamination. 1
• Do not provide supplemental oxygen liberally, as this is uniquely harmful in paraquat toxicity unlike other poisonings. 1, 2, 3
• Do not use gastric lavage routinely when activated charcoal is the evidence-based alternative. 1, 4
• Do not assume standard critical care oxygen targets apply—the 85-88% target is specific to paraquat and counterintuitive. 1, 2, 3

Pediatric Considerations

• Use warmed shower water at lower pressure during decontamination to prevent hypothermia and additional skin damage in children. 1
• Use heat lamps and blankets to prevent hypothermia during prolonged decontamination procedures. 1

Realistic Expectations

• Case fatality remains very high (often >50%) in all centers despite large variations in treatment, as there is no effective antidote. 4
• Treatment is largely supportive, and survival depends primarily on the amount of paraquat absorbed. 6, 4