What is the management of paraquat poisoning?

Management of Paraquat Poisoning

Immediately remove all contaminated clothing, wash exposed skin thoroughly, contact poison control, and avoid supplemental oxygen unless oxygen saturation falls below 85%—this restrictive oxygen approach is uniquely critical in paraquat poisoning because oxygen accelerates free radical-mediated lung injury. 1, 2, 3

Immediate Decontamination and Safety Measures

• Ensure rescuer safety first by wearing protective clothing and gloves when handling the patient, contaminated clothing, or body fluids to prevent secondary exposure 3

• Remove all contaminated clothing and jewelry immediately to stop ongoing dermal absorption 2, 3

• Thoroughly wash all exposed skin areas with copious amounts of water 1, 3

• Contact poison control centers immediately for expert guidance on case-specific management 1, 2, 3

Gastrointestinal Decontamination

• Administer multiple-dose activated charcoal (15-20g every 6 hours) only after securing the airway and achieving hemodynamic stability 1, 3

• Do not perform routine gastric lavage—activated charcoal or Fuller's earth are preferred decontamination agents as they work through adsorption rather than mechanical removal 1

• Never attempt decontamination before ensuring airway protection due to significant aspiration risk 1

The American College of Medical Toxicology specifically recommends against routine gastric lavage for paraquat poisoning 1. This represents a shift from older practices, as activated charcoal is more effective and safer 4.

Critical Oxygen Management (Most Important Pitfall)

• Target oxygen saturation of 85-88%—significantly lower than standard critical care targets 1, 2, 3

• Administer supplemental oxygen ONLY if SpO2 falls below 85% 1, 2, 3

• Reduce or stop oxygen therapy if saturation rises above 88% 1, 2, 3

• Oxygen dramatically worsens paraquat toxicity by accelerating free radical production and lung injury through increased oxidative stress 1, 3

This oxygen restriction is the most critical and counterintuitive aspect of paraquat management. Liberal oxygen administration—standard in most poisonings—is uniquely harmful here and will accelerate pulmonary fibrosis 1, 2.

Supportive Care and Monitoring

• Provide standard airway management with early intubation if needed for airway protection 2

• Treat hypotension and dysrhythmias with standard resuscitation measures 2

• Correct metabolic derangements as they develop 3

• Monitor for multiorgan failure including renal, hepatic, cardiac, and pulmonary dysfunction, as paraquat affects organs with high blood flow 5, 6

Enhanced Elimination Strategies

• Consider hemodialysis or hemoperfusion in the early phase (first 24-48 hours) to enhance paraquat elimination, though evidence for mortality benefit is limited 7, 4

• Continuous hemoperfusion with coated activated charcoal (approximately 8 hours/day over 2-3 weeks) has been reported in case series, though this is resource-intensive 4

Antioxidant Therapy (Adjunctive, Limited Evidence)

• N-acetylcysteine (300 mg/kg/day continuous infusion) has been used in case reports as an antioxidant, though evidence is limited to observational data 7

• Deferoxamine (100 mg/kg in 24 hours) has been reported in combination with acetylcysteine in survival cases 7

• S-carboxymethylcysteine (1500 mg for 2-3 weeks) has been used as an alternative antioxidant in resource-limited settings with reported mortality of 23% in mild-to-moderate cases 8

These antioxidant therapies lack high-quality evidence but may be considered as adjuncts after primary decontamination and supportive measures are established 7, 8.

Prognosis and Severity Assessment

• Mild poisoning (<20 mg/kg): Gastrointestinal symptoms only, full recovery expected 5

• Moderate-to-severe poisoning (20-40 mg/kg): Renal failure and delayed pulmonary fibrosis developing over days to weeks, high mortality 5

• Acute fulminant poisoning (>40 mg/kg): Multiple organ failure within hours, death within days, nearly universally fatal 5

• Urine dithionite test can help assess severity and prognosis 8

Advanced Rescue Therapy

• Bilateral lung transplantation may be considered for severe respiratory failure refractory to conventional treatment once paraquat levels are undetectable (typically 30+ days) and renal/hepatic function optimizes 6

• Extracorporeal membrane oxygenation (ECMO) can serve as a bridge to transplantation in select cases 6

Critical Pitfalls to Avoid

• Do not provide liberal supplemental oxygen—this is the most dangerous error unique to paraquat poisoning 1, 2, 3

• Do not delay airway protection to perform gastrointestinal decontamination 1

• Do not use routine gastric lavage when activated charcoal is available 1

• Do not underestimate the severity—even small ingestions (>20 mL of concentrated formulations) can be fatal 6