Emergency Management of Paraquat (Dipyridylium) Poisoning
Immediately contact poison control, ensure rescuer safety with full protective equipment, remove all contaminated clothing, perform gastric decontamination with activated charcoal if presenting within 1 hour, and critically—avoid supplemental oxygen unless SpO2 falls below 85%, as oxygen worsens paraquat toxicity. 1, 2
Immediate Rescuer and Healthcare Provider Safety
- Healthcare workers must wear gloves and full protective equipment when handling the patient's clothing or bodily fluids, as paraquat can be absorbed through skin or respiratory tract 3, 2
- Remove all contaminated clothing and jewelry immediately to prevent continued exposure 1
- Thoroughly wash all exposed skin areas 2
Critical First Steps
- Contact poison control center immediately for expert guidance—this is a Class 1 recommendation from the American Heart Association 1
- Activate emergency response systems without delay 4
- Assess airway, breathing, and circulation with standard BLS/ACLS protocols 1
Gastrointestinal Decontamination (Time-Sensitive)
- Consider multiple-dose activated charcoal (15-20g every 6 hours) only if presenting within 1 hour of ingestion and only after airway protection and hemodynamic stabilization 2
- Fuller's earth or bentonite may also prevent absorption if available 5, 6
- Never induce vomiting or administer ipecac—this is contraindicated due to aspiration risk 3
- Do not give water or milk to dilute the poison—this provides no benefit and may provoke emesis 3
Oxygen Management: The Critical Pitfall
This is the most important and counterintuitive aspect of paraquat management:
- Avoid supplemental oxygen unless SpO2 falls below 85% 1, 2
- Target oxygen saturation of 85-88%—significantly lower than typical critical care targets 1
- If SpO2 rises above 88%, reduce or stop oxygen therapy 1
- Rationale: Oxygen increases paraquat-induced free radical production and worsens lung injury through enhanced lipid peroxidation 2, 5, 7
- Historical evidence from animal models demonstrates that hypoxic environments (10% oxygen) reduced mortality from 78% to 32% in paraquat poisoning 7
Supportive Care and Monitoring
- Provide standard airway management if respiratory distress develops 1
- Treat hypotension and dysrhythmias according to standard protocols 1
- Administer benzodiazepines for seizures or severe agitation if they occur 1
- Maintain fluid and electrolyte replacement, particularly as acute kidney injury commonly develops 8, 9
- Monitor renal function closely—serum creatinine may rise rapidly (e.g., from 0.96 to 4.57 mg/dL within days) 9
Prognostic Assessment
- Plasma paraquat concentration is the most important prognostic indicator 5
- Proudfoot's curve can predict survival based on time since ingestion and plasma concentration 9
- Absence of caustic burns in the upper digestive tract indicates better prognosis 5
- Ingestion of ≥30 mg/kg or 50 mL of 21% solution typically results in multi-organ failure or death 6
Extracorporeal Therapy Considerations
- Hemoperfusion or hemodialysis may be considered, though evidence for toxicologically significant removal is limited 5, 8
- Continue extracorporeal therapy until paraquat cannot be detected in body fluids or dialysate 6
- These modalities are proven valuable if renal failure develops, but do not clearly improve survival in severe poisoning 8
Psychiatric Evaluation
- All patients with intentional paraquat ingestion require psychiatric evaluation before discharge 3