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

Hemoperfusion for Poisoning and Drug Overdose

Hemoperfusion should be considered for severe poisoning when specific toxins are involved and when conventional treatments fail, but it is not first-line therapy for most poisonings.

Indications for Hemoperfusion

Hemoperfusion is indicated in the following scenarios:

Primary Indications

• Severe barbiturate poisoning (particularly long-acting barbiturates like phenobarbital) with:

  • Prolonged coma
  • Respiratory depression requiring mechanical ventilation
  • Persistent toxicity despite multiple-dose activated charcoal treatment 1
  • Rising or persistently elevated serum barbiturate concentrations despite conventional treatment 2

• Severe salicylate poisoning with:

  • Altered mental status
  • Acute respiratory distress syndrome
  • Failure to respond to standard therapy (including sodium bicarbonate)
  • Severe acidemia (pH <7.20)
  • High salicylate concentrations (>7.2 mmol/L or >100 mg/dL) 2, 1

• Theophylline toxicity when:

  • Serum concentration >30 μg/mL with toxicity symptoms
  • Serum concentration >100 μg/mL regardless of symptoms
  • Intractable vomiting preventing use of multiple-dose activated charcoal
  • Seizures or cardiac arrhythmias that cannot be adequately controlled 3

Toxin Characteristics Favoring Hemoperfusion

• Highly protein-bound toxins with low volume of distribution
• Toxins with poor water solubility
• Toxins poorly cleared by hemodialysis 1

Preferred Extracorporeal Treatment Methods

Hemodialysis is generally preferred over hemoperfusion for most toxins due to:

• Better availability in most hospitals
• Lower risk of serious complications
• Similar effectiveness for many toxins 2, 1

Hemoperfusion should be considered when:

1. Hemodialysis is unavailable
2. The toxin is highly protein-bound with poor dialyzability
3. The toxin has specific affinity for charcoal adsorption 1

Effectiveness by Toxin Type

Highly Effective

• Long-acting barbiturates (phenobarbital)
• Theophylline (charcoal hemoperfusion increases clearance up to six-fold) 3
• Salicylates (when hemodialysis is not available) 2, 1

Limited Effectiveness

• Short-acting barbiturates (due to larger volume of distribution) 2, 1
• Drugs with weak extracellular distribution (digoxin, tricyclic antidepressants) 4
• Heavy metals 4

Treatment Protocol

1. Initiate standard supportive care first (airway management, hemodynamic support)

2. Continue conventional treatments during hemoperfusion:

   • Multiple-dose activated charcoal (if appropriate)
   • Urinary alkalinization for salicylates
   • Specific antidotes when available 2

3. Monitor during treatment:

   • Hemodynamic parameters
   • Mental status
   • Serum drug concentrations every 2-4 hours
   • Platelet count (risk of thrombocytopenia)
   • Calcium levels (risk of hypocalcemia) 1, 3

4. Treatment endpoint: Clinical improvement rather than specific drug level targets, including:

   • Improved mental status
   • Decreased vasopressor requirements
   • Resolution of respiratory depression 1

Complications of Hemoperfusion

• Thrombocytopenia
• Hypotension
• Hypocalcemia
• Leukopenia
• Air embolism
• Bleeding diatheses 1, 3

Common 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) 1

Alternative Approaches

When both hemodialysis and hemoperfusion are unavailable:

• Continuous renal replacement therapy
• Exchange transfusion (for neonates with salicylate poisoning) 2, 1

For most poisonings, supportive care remains the mainstay of therapy, with extracorporeal removal methods reserved for severe cases that fail to respond to conventional treatment 2, 5.