Biological valuation of extra-corporeal techniques in acute poisoning.

The efficiency of dialysis methods a/o hemoperfusion in acute poisoning cannot be clinically estimated, because: a) Concomitant intestinal absorption, hepatic metabolism and urinary excretion must be taken into account. b) With supportive treatment alone, spontaneous recovery usually occurs in 98% of the intoxications in Intensive Care Units. The efficiency of these methods can only be estimated biologically. Measuring the blood level at the beginning and the end of the treatment as well as measuring the clearances of the drug is misleading. A better method is to measure the amount of extracted drug, either indirectly by calculation (from hourly differences of arteriovenous measures of drug concentration multiplied by the blood flow) or directly by elution of the cartridge or measures in dialysis fluid. Plasma kinetics under dialysis a/o hemoperfusion should be compared with spontaneous toxicokinetic of the substance and not with pharmacokinetic data. The experience of toxicologists has shown dialysis a/o hemoperfusion to be ineffective for drugs with weak extra-cellular distribution (such as Digoxine, Tricyclic drugs, heavy Metals, Colchicine). In the case of intoxication with Paraquat or Paracetamol, there is a negative correlation between the amount of removed intoxicant and the survival: death is likely to occur when the procedure has been very productive. In the case of intoxication by hypnotic drugs, one hemodialysis a/o hemoperfusion allows the removal of an average of 4-12% of the ingested barbiturates, 7-17% of the ingested Meprobamate. Whether these results can be judged satisfactory, life-saving of insignificant is largely a matter of personal standards.