In this procedure the patient's blood is pumped through a charcoal cartridge.
Charcoal haemoperfusion has been greatly overused and overrated in poisoning. Perhaps the thrill of the procedure and its efficacy have been confused.
Drugs must have the following characteristics for there to be a significant increase in clearance from haemoperfusion
- Volume of distribution less than 3 L/kg
- Affinity for charcoal (or resin, if used instead)
More importantly, as adverse effects of haemoperfusion are more frequent than for haemodialysis, it is even more important that the toxic effects of the drugs should be serious, related to the plasma concentration of the drug, and not treatable easily by less invasive means. Also, haemoperfusion does not correct electrolyte or fluid imbalance.
Thus the number of drugs where haemoperfusion is indicated are very few and again generally limited to only selected patients with these poisonings. These drugs (linked to their indications) are listed below:
- Paraquat (first 2-3 hours only)
Adverse effects are significantly more common than with haemodialysis. This is due to the charcoal binding to a number of components in the blood and perhaps also to a lack of familiarity with the equipment, which is used infrequently in most centres. The most significant adverse effects are
- Haemorrhage secondary to
- Consumptive coagulopathy