Charcoal Hemoperfusion in Severe Poisoning
Charcoal hemoperfusion is now largely superseded by hemodialysis for most severe poisonings, but remains indicated primarily for specific toxins including paraquat, carbamazepine, and certain organophosphates when hemodialysis is unavailable or less effective.
Current Role and Indications
Primary Indications
For salicylate poisoning, hemodialysis is the preferred extracorporeal treatment modality over hemoperfusion 1. While hemoperfusion can remove salicylates (clearance ~7.5 mL/min), this is several-fold inferior to hemodialysis, which can achieve clearances exceeding 100 mL/min 1.
However, charcoal hemoperfusion remains valuable for:
Paraquat poisoning: Hemoperfusion should be performed as "continuous hemoperfusion" for approximately 8 hours daily over 2-3 weeks 2. This aggressive approach, combined with oral activated charcoal, offers the best chance to reduce mortality in this extremely dangerous poisoning.
Carbamazepine overdose: Hemoperfusion demonstrates significant efficacy with peak clearances of 69 mL/min and extraction ratios ranging from 0.46 to 0.02 3. Cartridge saturation typically occurs around 7 hours of treatment.
Organophosphate poisoning (e.g., dichlorvos/DDVP): Hemoperfusion achieves mean clearances of 87±17 mL/min with 44%±11% reduction rates 4. Treatment significantly reduces mortality (7.5% vs 34.1% without hemoperfusion), shortens ICU stays, and decreases atropine requirements.
Barbiturate poisoning: Historical use showed clearance capacity, though serum concentrations decreased only 17-42% per 3.5-hour session 5. Longer perfusion durations are recommended, particularly for phenobarbital.
Procedural Parameters
Flow Rates and Duration
- Blood flow rate: 200-300 mL/min is optimal in adults, typically achieved via AV shunt in the forearm 6
- Session duration:
Cartridge Saturation
Monitor for cartridge saturation, which occurs when extraction ratios decline significantly:
- For carbamazepine, saturation typically occurs at 7 hours (extraction ratio ≤0.2 at 150 mL/min flow) 3
- Phenobarbital shows less rapid saturation, maintaining capacity beyond 3.5 hours 5
Important Caveats and Complications
Technical Complications
- Thrombocytopenia: Decrease in platelet counts is a principal complication 6
- Microemboli: Charcoal particle embolization can occur but is minimized with coated charcoal cartridges 6
Clinical Limitations
For paraquat poisoning, hemoperfusion has minimal effect on preventing acute kidney injury in severe cases 7. The primary benefit is toxin removal from plasma, not renal protection. All patients who died in one series developed non-oliguric renal failure despite hemoperfusion 7.
When NOT to Use Hemoperfusion
For salicylate poisoning, do not delay hemodialysis in favor of hemoperfusion 1. Intermittent hemodialysis is the preferred modality (1D recommendation), with hemoperfusion acceptable only if hemodialysis is unavailable 1.
Clinical Monitoring
- Measure toxin concentrations in afferent and efferent loops to calculate extraction ratios and assess cartridge efficacy 3
- Monitor for clinical improvement: consciousness level, respiratory status, and organ-specific toxicity markers
- For organophosphates, track cholinesterase activity recovery and reduction in atropine requirements 4