What is the treatment regimen for a patient with paraquat poisoning, including medication doses?

Treatment Regimen for Paraquat Poisoning

Immediately contact poison control, remove contaminated clothing, perform skin decontamination, administer multiple-dose activated charcoal (15-20g every 6 hours) after airway protection, and critically—restrict oxygen therapy to only when SpO2 falls below 85%, targeting 85-88% saturation. 1, 2

Immediate Decontamination and Safety

Healthcare Worker Protection

• Wear gloves and protective clothing when handling the patient or any contaminated materials to prevent secondary exposure 2
• Remove all contaminated clothing and jewelry immediately 1
• Thoroughly wash all exposed skin areas to prevent continued dermal absorption 2

Gastrointestinal Decontamination

• Administer multiple-dose activated charcoal at 15-20g every 6 hours, but only after securing the airway and achieving hemodynamic stability 2, 3
• Do not perform routine gastric lavage—activated charcoal or Fuller's earth are preferred decontamination agents through adsorption rather than mechanical removal 3, 4
• A critical pitfall is delaying airway protection to perform decontamination; secure the airway first due to significant aspiration risk 3

Critical Oxygen Management (Unique to Paraquat)

This is the most important deviation from standard critical care protocols:

• Avoid supplemental oxygen unless SpO2 falls below 85% 1, 2, 3
• Target oxygen saturation of 85-88%, which is dramatically lower than typical critical care targets 1, 2, 3
• Reduce or stop oxygen therapy if saturation rises above 88% 1, 2, 3
• The rationale: oxygen accelerates paraquat-induced free radical production and dramatically worsens lung injury 2, 3
• This represents a unique management principle where liberal oxygen supplementation—standard in most poisonings—is actively harmful 3

Antioxidant Therapy

While not included in the most recent guideline recommendations, case reports suggest potential benefit:

• N-acetylcysteine: 300 mg/kg/day as continuous infusion for up to 3 weeks 5
• Deferoxamine: 100 mg/kg over 24 hours 5
• Vitamin E has been reported in combination therapy 6
• These antioxidants may limit systemic toxicity when combined with decontamination measures, though evidence comes from case reports rather than controlled trials 5, 6

Extracorporeal Elimination

• Consider hemodialysis or hemoperfusion early to enhance elimination of absorbed paraquat 5, 6, 4
• Continue until paraquat cannot be detected in body fluids or dialysate 4
• Combined with forced diuresis using furosemide, mannitol, and IV fluids 4

Standard Supportive Care

• Provide standard airway management if respiratory distress develops 1, 2
• Treat hypotension and dysrhythmias according to standard protocols 1
• Administer benzodiazepines for seizures or severe agitation if they occur 1
• Correct metabolic derangements 2
• Maintain continuous contact with poison control center for evolving treatment recommendations 1

Prognostic Considerations

The severity of poisoning correlates with dose:

• Mild poisoning: <20 mg/kg paraquat ion—gastrointestinal symptoms only, full recovery expected 7
• Moderate to severe: 20-40 mg/kg—renal failure and delayed pulmonary fibrosis, death in majority of cases within 2-3 weeks 7
• Acute fulminant: >40 mg/kg—multiple organ failure, death within hours to days 7
• Plasma levels ≥0.16 mg/ml at 16-20 hours post-ingestion are considered lethal 8

Common Pitfalls to Avoid

• Never provide liberal supplemental oxygen—this is uniquely harmful in paraquat toxicity and represents the most critical management error 2, 3
• Do not delay airway protection to perform gastrointestinal decontamination 3
• Do not use routine gastric lavage when activated charcoal is the evidence-based alternative 3
• Do not underestimate dermal absorption—even through burned or disrupted skin, fatal absorption can occur 8