What is the management approach for paraquat poisoning?

Management of Paraquat Poisoning

Early intervention with decontamination, hemoperfusion, immunosuppressive therapy, and antioxidant treatment is critical for managing paraquat poisoning, with strict oxygen restriction to prevent worsening lung injury.

Initial Management and Decontamination

• Remove contaminated clothing and perform thorough skin decontamination with soap and water 1
• Healthcare providers must wear appropriate protective equipment (gloves) to prevent secondary exposure 1
• Perform gastric lavage if within 1-2 hours of ingestion 1
• Administer activated charcoal orally as soon as possible to reduce absorption 1, 2

Extracorporeal Elimination

• Initiate hemoperfusion with activated charcoal within 2-4 hours of ingestion 1
• Hemoperfusion efficacy decreases significantly after the first 4 hours post-ingestion 1
• Consider "continuous hemoperfusion" (approximately 8 hours/day) for 2-3 weeks in severe cases 2
• Monitor for and manage renal failure with appropriate fluid management and dialysis if needed 1

Respiratory Management (Critical)

• Restrict supplemental oxygen to target saturation of 85-88% 1
• Do not administer high-concentration oxygen even in respiratory failure, as this accelerates paraquat-induced lung damage 1
• Avoid mechanical ventilation with high oxygen concentrations when possible 1
• Early intubation may be necessary for airway protection, but use caution with oxygen settings 1

Immunosuppressive and Antioxidant Therapy

• Implement combined immunosuppressive therapy with:

  • Methylprednisolone
  • Cyclophosphamide
  • Dexamethasone 1

• Administer antioxidant therapy:

  • N-acetylcysteine (300 mg/kg/day for up to 3 weeks) 1, 3
  • Consider deferoxamine (100 mg/kg in 24h) in severe cases 3
  • S-carboxymethylcysteine (1500 mg for 2-3 weeks) may be used as an alternative where N-acetylcysteine is unavailable 4

Renal and Hepatic Management

• Monitor renal function closely as acute kidney injury occurs in approximately 50% of cases 1
• Watch for non-oliguric renal failure, which is common 1, 3
• For severe renal impairment, consider continuous kidney replacement therapy (CKRT) if intermittent hemodialysis is unavailable 1
• Monitor liver function tests for hepatic injury 3

Prognostic Indicators

• Plasma paraquat concentrations within the first 24 hours are important prognostic indicators 1, 5
• Urine and plasma dithionite tests help determine severity 1, 4
• Poor prognostic factors include:
  • Higher ingested amounts (>50 mg/kg often fatal within 72 hours) 5
  • Development of organic renal failure 5
  • Severe caustic gastric lesions on endoscopy 5

Special Considerations

• Consult with a regional poison center or toxicologist immediately (US: 1-800-222-1222) 1
• Pediatric patients should follow similar protocols as adults, with appropriate dose adjustments 1
• Different routes of exposure affect prognosis (skin/inhalation exposure has better outcomes than ingestion) 5

Common Pitfalls to Avoid

1. Delaying hemoperfusion beyond 4 hours post-ingestion significantly reduces its effectiveness 1
2. Administering high-concentration oxygen, which worsens paraquat-induced lung injury 1
3. Failing to implement both immunosuppressive and antioxidant therapies concurrently 1
4. Overlooking the importance of early and aggressive gastrointestinal decontamination 2
5. Underestimating the severity of poisoning based on initial presentation (multi-organ failure may develop later) 6