When is hemoperfusion (blood purification) recommended for treating poisoning?

Hemoperfusion Recommendations for Poisoning Treatment

Hemoperfusion is recommended for severe poisoning when specific clinical criteria are met, particularly for long-acting barbiturates, salicylates, and select toxins that are not adequately cleared by other methods. 1

Indications for Hemoperfusion

For Barbiturate Poisoning:

• Primary indications (strong recommendations): 1

  • Prolonged coma is present or expected
  • Shock persists despite fluid resuscitation
  • Persistent toxicity despite multiple-dose activated charcoal (MDAC) treatment
  • Respiratory depression requiring mechanical ventilation

• Secondary indications (weaker recommendations):

  • Serum barbiturate concentration rises or remains elevated despite MDAC
  • More effective for long-acting barbiturates than short-acting ones

For Salicylate Poisoning: 1

• Primary indications:
  • Altered mental status
  • Acute respiratory distress syndrome requiring supplemental oxygen
  • Standard therapy is failing
  • High salicylate concentrations:

    • 7.2 mmol/L (100 mg/dL) regardless of symptoms

    • 6.5 mmol/L (90 mg/dL) in patients with impaired kidney function

  • Severe acidemia (pH <7.20)

Modality Selection Algorithm

1. First-line therapy: Intermittent hemodialysis is preferred over hemoperfusion for most toxins 1

   • Higher clearance rates (up to 188 mL/min for phenobarbital with HD vs 163 mL/min with HP)
   • Better availability in most centers

2. When to use hemoperfusion:

   • When hemodialysis is unavailable 1
   • For highly protein-bound toxins with low volume of distribution 1
   • For toxins with poor water solubility

3. Alternative options when both HD and HP are unavailable:

   • Continuous renal replacement therapy (CRRT) 1
   • Exchange transfusion (for neonates with salicylate poisoning) 1

Effectiveness by Toxin Type

Highly Effective (Consider as first-line):

• Long-acting barbiturates (phenobarbital) 1, 2
• Salicylates 1

Moderately Effective:

• Short-acting barbiturates (limited by larger volume of distribution) 1
• Severe organophosphate poisoning (limited evidence) 3

Limited or Questionable Effectiveness: 4, 5

• Drugs with weak extracellular distribution (digoxin, tricyclic antidepressants)
• Heavy metals
• Colchicine
• Paraquat (debatable)

Practical Implementation

Monitoring During Treatment:

• Clinical improvement is the primary endpoint for stopping treatment 1
• Monitor for:
  • Hemodynamic stability
  • Improved mental status
  • Decreased vasopressor requirements
  • Resolution of respiratory depression

Common Complications: 6, 5

• Thrombocytopenia (common but rarely clinically significant)
• Hypotension
• Hypocalcemia
• Leukopenia
• Mechanical problems (air embolism)

Special Considerations

• For phenobarbital poisoning, hemoperfusion can remove >30% of ingested dose in a single 5-hour session 1, 7
• For patients with hemodynamic instability, continuous venovenous hemodiafiltration may be considered as an alternative 7
• Multiple-dose activated charcoal should be continued during extracorporeal treatment for barbiturate poisoning 1

Key Pitfalls to Avoid

1. Delaying extracorporeal treatment in severe poisoning cases
2. Relying solely on drug levels rather than clinical status to guide treatment decisions
3. Using hemoperfusion for toxins with poor adsorption to charcoal
4. Stopping treatment too early based on drug levels alone rather than clinical improvement
5. Failing to optimize treatment parameters (blood flow, filter surface area)

Remember that the decision to use hemoperfusion should be based on the severity of poisoning, the specific toxin involved, and the availability of resources, with intermittent hemodialysis being the preferred modality when available.