What is the management approach for paraquat (herbicide) consumption poisoning?

Management of Paraquat Poisoning

Immediately contact poison control center, remove all contaminated clothing, avoid supplemental oxygen unless SpO2 falls below 85%, and do NOT induce vomiting or administer activated charcoal—the prognosis is extremely poor with mortality rates exceeding 50% even with aggressive treatment. 1

Immediate Actions and Decontamination

First Steps

• Contact poison control center immediately for expert guidance as this is a time-critical emergency with rapidly evolving toxicity 1
• Remove all contaminated clothing and jewelry to prevent continued dermal absorption 1
• Healthcare workers must wear appropriate personal protective equipment including gloves and protective clothing when handling the patient or contaminated materials 1

What NOT to Do

• Do not induce vomiting as this increases exposure time and risk of aspiration 2
• Do not administer activated charcoal unless specifically directed by poison control—evidence shows treatments including fuller's earth and forced diarrhea do not modify outcomes 3
• Do not give anything by mouth unless advised by poison control or emergency medical personnel 2

Critical Oxygen Management

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

• Administer oxygen ONLY if SpO2 falls below 85%—supplemental oxygen worsens paraquat toxicity through enhanced free radical generation 1
• Target oxygen saturation is 85-88%, which is dramatically lower than typical critical care targets 1
• Reduce or stop oxygen if SpO2 rises above 88% to minimize oxidative lung injury 1
• Avoid supplemental oxygen unless the patient is severely hypoxemic 1

Supportive Care

Airway and Hemodynamic Management

• 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

Ongoing Monitoring

• Maintain continuous contact with poison control center for evolving treatment recommendations 1
• Monitor for multiple organ failure including renal, hepatic, cardiac, and pulmonary dysfunction 4

Prognostic Factors

Understanding prognosis helps guide realistic discussions with families:

Dose-Related Outcomes

• Above 50 mg/kg: Death from circulatory failure within 72 hours 3
• 35-50 mg/kg: Progressive pulmonary fibrosis develops 3
• Below 20 mg/kg: Mild poisoning with possible full recovery 4
• Intravenous exposure has extremely poor prognosis with death typically within 5 days despite aggressive treatment 5

Plasma Concentration Thresholds for Survival

Patients are likely to survive only if plasma paraquat concentrations do not exceed:

• 2.0 mg/L at 4 hours
• 0.6 mg/L at 6 hours
• 0.3 mg/L at 10 hours
• 0.16 mg/L at 16 hours
• 0.1 mg/L at 24 hours 3

Other Prognostic Indicators

• Delay between ingestion and last meal (food adsorbs and neutralizes paraquat) 3
• Presence of caustic gastric lesions on early endoscopy indicates worse prognosis 3
• Development of organic renal failure predicts poor outcome 3

Common Pitfalls

• Administering supplemental oxygen reflexively: This is the most critical error—oxygen accelerates paraquat-induced lung injury through redox cycling and reactive oxygen species generation 1, 6
• Attempting aggressive decontamination: Evidence shows that hemodialysis, hemoperfusion, and forced diuresis do not modify initial prognosis 3
• Unrealistic expectations: Even with optimal management including pulse steroids and cyclophosphamide, survival after moderate-to-severe ingestion is rare 5, 7