Is dialysis mandatory for a patient who has been poisoned?

Is Dialysis Mandatory for Poisoned Patients?

No, dialysis is not mandatory for all poisoned patients—it is only indicated for specific toxins with particular clinical features, and most poisonings are managed without extracorporeal treatment. 1, 2, 3

When Dialysis IS Required

Dialysis becomes necessary only when specific criteria are met for dialyzable toxins. The decision depends on three key factors: the toxin's characteristics, clinical severity, and whether toxicity will persist despite standard care 3.

Specific Toxins Requiring Dialysis

Ethylene Glycol Poisoning:

• Intermittent hemodialysis is strongly recommended when glycolate concentration >12 mmol/L, anion gap >27 mmol/L, or severe features (coma, seizures, acute kidney injury KDIGO stage 2-3) are present 4, 1, 5
• Conditional indications include glycolate 8-12 mmol/L, anion gap 23-27 mmol/L, or ethylene glycol concentration ≥50 mg/dL 1, 5
• CRRT is preferred only if intermittent hemodialysis cannot be initiated quickly or if marked brain edema exists 4, 1

Salicylate Poisoning:

• Strong recommendation for hemodialysis when levels >7.2 mmol/L (100 mg/dL) with altered mental status, ARDS, or failure of standard therapy 2
• Conditional recommendation for levels >6.5 mmol/L (90 mg/dL), with lower thresholds for impaired kidney function 2

Beta-Blocker Toxicity (Atenolol/Sotalol only):

• Hemodialysis is indicated for refractory bradycardia, hypotension despite vasopressors, or need for extracorporeal life support 4, 1
• During dialysis, maintain magnesium >1 mmol/L and potassium 4.5-5 mmol/L to prevent torsades de pointes 4, 1
• Most beta-blockers (propranolol, carvedilol, labetalol) are NOT dialyzable due to high protein binding 4

Lithium and Long-Acting Barbiturates:

• Hemodialysis recommended for persistent shock after fluid resuscitation, significant renal dysfunction, or respiratory failure requiring mechanical ventilation 1

When Dialysis Is NOT Needed

The vast majority of poisonings do not require dialysis 3. Extracorporeal treatment is ineffective for toxins that are:

• Highly protein-bound (>80%) 3
• Lipid-soluble with large volume of distribution 3, 6
• Have high endogenous clearance 3
• High molecular weight 6

Technical Optimization When Dialysis IS Indicated

Modality Selection:

• Intermittent hemodialysis is first-line for all dialyzable poisons when available 4, 1, 2
• Use high-flux dialyzers with largest available surface area 1
• Maximize blood flow to 300-400 mL/min and optimize dialysate/effluent flow rates 1

Critical Medication Adjustments:

• Increase fomepizole dosing to every 4 hours during hemodialysis (it is dialyzable) 1, 5
• Increase ethanol maintenance to 250-350 mg/kg/hour during hemodialysis 5

Cessation Criteria

Do not stop dialysis based solely on toxin concentration or clinical improvement alone 4, 1, 2. Continue until specific biochemical targets are met:

• Ethylene glycol: Anion gap <18 mmol/L AND ethylene glycol <4 mmol/L (25 mg/dL) AND acid-base abnormalities corrected 4, 1, 5
• Beta-blockers: Clinical improvement with appropriate heart rate/blood pressure, weaning of vasopressors, and cessation of dysrhythmias 4, 1
• Salicylates: Do not stop based on clinical improvement if levels remain >7.2 mmol/L 1, 2

Critical Pitfalls to Avoid

• Never delay hemodialysis while attempting less effective modalities when clear indications exist 1, 2
• Do not use peritoneal dialysis when hemodialysis is available—it provides inadequate clearance 4, 1
• Do not assume all poisonings benefit from dialysis; most do not meet criteria for extracorporeal treatment 3
• Avoid stopping dialysis prematurely based on symptom improvement without meeting biochemical endpoints 1, 2