What is the treatment for paraquat poisoning?

Treatment for Paraquat Poisoning

Paraquat poisoning requires immediate aggressive decontamination with activated charcoal or Fuller's earth after airway protection, strict oxygen restriction (target SpO2 85-88%), and early contact with poison control—there is no specific antidote and prognosis remains poor despite all interventions. 1, 2, 3

Immediate Rescuer and Healthcare Worker Safety

• Remove all contaminated clothing and jewelry immediately while wearing appropriate personal protective equipment including gloves and protective clothing to prevent secondary exposure. 2, 3
• Thoroughly wash all exposed skin areas with soap and water using copious irrigation 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 during decontamination. 1

Critical Oxygen Management - Unique to Paraquat

This is the most critical pitfall to avoid: Paraquat toxicity is dramatically worsened by supplemental oxygen through increased free radical production and accelerated lung injury. 1, 2, 3

• Only administer oxygen if SpO2 falls below 85%—this is far lower than standard critical care practice. 1, 2, 3
• Target oxygen saturation of 85-88%, not the typical 92-96%. 1, 2, 3
• Reduce or stop oxygen therapy if saturation rises above 88%. 1, 2, 3
• High oxygen concentrations increase paraquat-induced free radical production and worsen pulmonary fibrosis. 3, 4

Gastrointestinal Decontamination

Never delay airway protection to perform decontamination—secure the airway first given significant aspiration risk. 1

• The American College of Medical Toxicology recommends against routine gastric lavage for paraquat poisoning. 1
• Activated charcoal (15-20g every 6 hours) or Fuller's earth are the preferred decontamination agents through adsorption rather than mechanical removal. 1, 3, 4, 5
• Administer multiple-dose activated charcoal only after airway protection and hemodynamic stabilization. 1, 3
• Fuller's earth, activated charcoal, and resins may prevent some absorption but treatment efficacy remains limited. 4, 5

Supportive Care and Monitoring

• Contact poison control centers immediately and maintain continuous contact for evolving treatment recommendations. 1, 2, 3
• Provide standard airway management if respiratory distress develops. 2, 3
• Treat hypotension and dysrhythmias according to standard advanced life support protocols. 2, 3
• Administer benzodiazepines for seizures or severe agitation if they occur. 2
• Correct metabolic derangements as they develop. 3

Prognostic Indicators

• Plasma paraquat concentration is the most important prognostic indicator—the quantity absorbed determines outcome. 4, 6
• Ingestion of ≥50 mg/kg typically causes death within 2 days; lower doses may delay death for several weeks. 4
• Absence of caustic burns in the upper digestive tract indicates better prognosis. 4
• Three clinical severity categories exist: mild (<20 mg/kg), moderate-to-severe (20-40 mg/kg), and acute fulminant (>40 mg/kg). 6

Treatments with Limited or No Proven Efficacy

Despite aggressive multimodal therapy, no specific antidote exists and prognosis remains uniformly poor worldwide. 7

• Hemodialysis, hemoperfusion, and forced diuresis have been attempted with no clear improvement in survival rates. 4, 5
• Free radical scavengers (superoxide dismutase, glutathione peroxidase, N-acetylcysteine) have failed to alter outcomes in most poisoned patients. 4
• One case report suggested potential benefit from early antioxidant therapy with deferoxamine (100 mg/kg/24h) and continuous acetylcysteine infusion (300 mg/kg/d for 3 weeks), but this remains unvalidated. 8
• Theoretical treatments including immunotherapy, NADPH repletion, and lung transplantation still require clinical validation. 4

Key Clinical Pitfalls to Avoid

• Do not provide supplemental oxygen liberally—this is uniquely harmful in paraquat toxicity unlike other poisonings. 1, 3
• Do not delay airway protection to perform gastrointestinal decontamination. 1
• Do not use gastric lavage routinely when activated charcoal is the evidence-based alternative. 1
• Do not underestimate the poor prognosis—long-term survivors are few and typically have significant GI and pulmonary complications. 7

Mechanism of Toxicity

Paraquat accumulates in lung tissue where it forms free radicals, induces lipid peroxidation, and depletes NADPH, producing diffuse alveolitis followed by extensive pulmonary fibrosis. 4 Multi-organ failure affecting the lungs, GI tract, kidneys, liver, heart, and other organs commonly occurs. 7, 6