Should hemodialysis be used as primary treatment for acute paraquat poisoning?

Hemodialysis Should NOT Be Used as Primary Treatment for Acute Paraquat Poisoning

Hemodialysis and hemoperfusion are ineffective at preventing mortality in paraquat poisoning because paraquat rapidly distributes into tissues within hours of ingestion, and extracorporeal removal only clears the central (plasma) compartment while tissue concentrations remain lethally elevated. 1, 2

Why Extracorporeal Treatment Fails in Paraquat Poisoning

Pharmacokinetic Limitations

• Paraquat is actively transported against a concentration gradient into lung, kidney, liver, and other tissues within 2-4 hours of ingestion, creating a large peripheral tissue compartment that is inaccessible to dialysis 1
• Even with combined hemoperfusion-hemodialysis achieving blood clearances of 151 mL/min, tissue paraquat levels remain elevated (lung tissue 4.0 μg/g, skeletal muscle 9.4 μg/g) and patients still die from multi-organ failure 1
• After extracorporeal treatment, significant rebound of blood paraquat occurs as the toxin redistributes from tissues back into plasma 1

Clinical Evidence of Ineffectiveness

• In documented cases where hemoperfusion-hemodialysis was initiated within 3 hours of ingestion with initial blood paraquat of 15.8 μg/mL, patients still developed renal and hepatic failure and died within 5 days despite efficient plasma clearance 1
• Hemoperfusion clearance of paraquat averages 111 mL/min (range 13-162 mL/min), which is comparable to or slightly better than renal clearance of 79.8 mL/min, but neither prevents the lethal pulmonary fibrosis and multi-organ failure 2
• The mortality rate for severe paraquat poisoning remains extremely high (>80% for ingestions >20 mg/kg) regardless of extracorporeal treatment 3

Appropriate Management Strategy

Immediate Gastrointestinal Decontamination (Within 1 Hour)

• Administer Fuller's Earth (30% suspension, 1-2 L orally) or activated charcoal (1 g/kg) immediately to bind unabsorbed paraquat in the gut 4
• Repeat Fuller's Earth or activated charcoal every 2-4 hours for the first 12-24 hours, as paraquat undergoes enterohepatic recirculation 4
• Add magnesium sulfate cathartic to enhance gastrointestinal elimination 4

Supportive Care as Primary Treatment

• Maintain strict fluid and electrolyte balance to support renal function for endogenous paraquat elimination 3
• Avoid supplemental oxygen unless absolutely necessary (maintain PaO2 40-60 mmHg), as hyperoxia accelerates paraquat-induced pulmonary toxicity through enhanced free radical generation 4
• Consider immunosuppression with high-dose corticosteroids and cyclophosphamide, though evidence is limited 4, 3

Limited Role for Extracorporeal Treatment

• Hemoperfusion or hemodialysis may be considered only if initiated within 2-4 hours of a massive ingestion AND primarily to support renal function if acute kidney injury develops, not for toxin removal 2, 3
• Do not delay supportive care or gastrointestinal decontamination to arrange extracorporeal treatment, as the window for effective plasma clearance closes rapidly 1
• Renal replacement therapy should follow standard acute kidney injury indications (hyperkalemia, severe acidosis, uremia) rather than toxin removal goals 3

Critical Pitfalls to Avoid

• Never prioritize extracorporeal treatment over immediate gastrointestinal decontamination—the only intervention with potential benefit is preventing absorption before tissue distribution occurs 4
• Avoid liberal oxygen therapy, as maintaining relative hypoxia (PaO2 40-60 mmHg) may slow pulmonary toxicity progression 4
• Do not falsely reassure patients or families based on successful plasma clearance, as tissue paraquat concentrations determine outcome 1
• Recognize that prognosis is determined by ingested dose and time to presentation—plasma paraquat >2 μg/mL at 4 hours or >0.1 μg/mL at 24 hours predicts near-certain mortality regardless of treatment 1, 3