Removal of paraquat from blood by haemoperfusion over sorbent materials

Haemoperfusion over Ion Exchange Resins and Polymeric Adsorbents

A review of the development and application of haemoperfusion over ion exchange resins and polymeric adsorbents is presented. Aspects of biocompatibility and ion balance are discussed.

The Effect of Hemoperfusion over Uncoated and Polymer — Coated Charcoal on Hematological Levels in the Conscious Rat

An investigation has been made of the suitability of a rat hemoperfusion system for the evaluation of hematological changes induced by charcoal hemoperfusion. The investigation studied the influence on erythrocyte, leucocyte and thrombocyte levels of repeated hemoperfusion over Norit RBX1 charcoal, hemoperfusion over polymer-coated Norit RBX1 and hemoperfusion over uncoated spherical charcoal. Controls included animals subjected to hemoperfusion through empty columns and animals cannulated only. The results indicate that changes in erythrocyte and leucocyte levels are due principally to passage of blood through the extracorporeal circuit rather than contact with the adsorbent but that changes in thrombocyte levels are dependent on the type of charcoal and the nature and extent of polymer coating. The investigation suggests that the rat hemoperfusion system is a suitable procedure for the assessment of the compatibility of adsorbents to be used in hemoperfusion.

Hemoperfusion for the treatment of poisoning: technology, determinants of poison clearance, and application in clinical practice

Hemoperfusion is an extracorporeal treatment based on adsorption, historically reserved for the treatment of acute poisonings. Its use was popularized in the 1970s after several in vitro and animal experiments had demonstrated its efficacy, and was even preferred over hemodialysis in the management of overdosed patients. With the advent of new and more efficient dialytic modalities, hemoperfusion is now less frequently performed in the Western world. However, hemoperfusion still remains popular in developing countries. The present article reviews the technique of hemoperfusion, the factors influencing poison clearance through adsorption and its current applications.

Three Controversial Issues in Extracorporeal Toxin Removal

The optimal method of extracorporeal removal of many toxic compounds is often a matter of debate. Due to the lack of well-designed studies, we are often left with circumstantial evidence, and we must exercise our best clinical judgment as to whether extracorporeal drug removal is beneficial and if so, by what method. It is clear, however, that rapidity in toxin removal is beneficial. We present three issues dealing with extracorporeal removal of toxins for which there is no definitive answer but which may arise in clinical practice. The first is whether continuous renal replacement therapy (CRRT) is better at removing dialyzable toxins than classic hemodialysis. The second is whether charcoal hemoperfusion is at all useful in treating paraquat poisoning. Finally, is any modality of extracorporeal treatment useful in the treatment of amatoxin poisoning? After a thorough literature review, it is evident that definitive answers are not strikingly apparent. However, extracorporeal treatment in the latter two instances may have potential benefit and may be the only hope for patient survival. Due to the urgent nature of treatment for poisoning, as well as the somewhat obscure nature of these issues, there may never be well-designed evidence-based studies to help guide us. In the meantime, we must continue to use less than ideal evidence and our own experience in dealing with these controversial issues to guide our decision-making process.

Effect of aggressive haemoperfusion on the clinical course of patients with paraquat poisoning

The effect of aggressive haemoperfusion; i.e. haemoperfusion of 10 h or more during the first 24 h after ingestion, on the clinical course of paraquat poisoning was studied. Among 40 patients admitted within 15 h after ingestion of paraquat with an SIPP of less than 100 (h x micrograms ml-1), 21 received aggressive haemoperfusion and 19 received conventional haemoperfusion; i.e. haemoperfusion of less than 10 h during the same period. Survival rates of patients with severity between an SIPP of 100 and Proudfoot's curve in the two groups were compared by the log-rank test. Aggressive haemoperfusion did not improve the outcome but did improve the survival rates; that is, the number of patients surviving at particular points in time (P < 0.05). The length of haemoperfusion for the aggressive haemoperfusion group was longer than that for the conventional group on the first day (P < 0.001), but the difference was insignificant during the following two days. Neither the time from ingestion to haemoperfusion, urine volume from the first to third day, nor initial plasma-paraquat concentrations and SIPP were significant between groups. These findings imply that aggressive haemoperfusion reduces the severity of paraquat poisoning and elongates survival time. We, therefore, propose that the efficacy of more aggressive haemoperfusion, such as the 'continuous haemoperfusion' proposed by Okonek et al., should be further studied.

The new black magic: activated charcoal and new therapeutic uses

Activated charcoal has been used for centuries as antidotal therapy for poisonings. New variations of charcoal therapy have developed over the last two decades. These modifications include multiple-dose activated charcoal (MDAC) therapy, charcoal hemoperfusion, and a new "superactive" charcoal (SAC). Recent literature suggests using initial charcoal therapy instead of ipecac as a first-line antidotal agent for many acute poisonings. The palatability of charcoal slurries has been enhanced by the addition of carboxymethylcellulose, sucrose, saccharin, chocolate syrup, or sorbitol. The new SAC has shown to adsorb 1.7 to 4 times the amount of substance tested compared with other activated charcoal preparations. Multiple-dose activated charcoal therapy has been shown effective in treating phenobarbital, digoxin, digitoxin, theophylline, and dapsone intoxications, among others. The problems associated with charcoal hemoperfusion therapy have been partially alleviated, and it is now alternative therapy for the seriously intoxicated patient.

Specific removal of paraquat by hemoperfusion through antiparaquat conjugated agarose-polyacrolein microsphere beads

A novel specific adsorbent for removal of paraquat from blood has been developed. Immobilized antiparaquat antibodies provide the specificity and high affinity of the adsorbent. The antibodies were raised in rabbits and goats immunized with an analogue of paraquat, conjugated to bovine serum albumin (BSA). Specific antiparaquat antibodies were isolated from the animals' sera by affinity chromatography. The antibodies were polyvalently bound to crosslinked agarose-polyacrolein microsphere beads (APAMB). Antiparaquat conjugated beads (APB) were used as packing material in a hemoperfusion column for detoxification of paraquat and were compared to activated charcoal. In vitro and in vivo experiments showed specific and enhanced rate of removal of paraquat from plasma and blood by using APB. Minimal alteration of the formed elements and plasma constituents of the blood was observed.

The effect of repeated hemoperfusion over charcoal in the conscious rat on liver pathophysiology

An investigation has been made into the effects of repeated charcoal hemoperfusion in the rat on liver pathophysiology. Animals underwent hemoperfusion over Norit RBX1 charcoal using a technique which allowed perfusion in the unrestrained and conscious state, thus minimizing any possible effects from stress and eliminating the necessity of repeated anesthesia. Controls consisted of animals subjected to perfusion through empty columns and animals cannulated only. Liver weight, function, and histology were recorded at various times following hemoperfusion and control procedures. The results show that repeated charcoal hemoperfusion is well tolerated in the rat and can be performed safely with no deleterious effects on liver tissue.

Activated charcoal haemoperfusion via an extracorporeal circuit in the unrestrained and unanaesthetized rat

Repeated haemoperfusion over activated charcoal was performed in unanaesthetized and unrestrained rats, using a specially designed system. This allowed the effects of haemoperfusion on body weight, organ weight and various biochemical and haematological parameters to be studied, without the possible influence of repeated stress and exposure to anaesthetic agents. The procedure was well tolerated, even after 4 consecutive haemoperfusions. Changes in body weight occurred, but no significant difference was noticed between animals subjected to 4 consecutive haemoperfusions and those perfused through empty columns. Organ weight of liver and spleen were comparable to control values, but kidney weight increased after haemoperfusion over activated charcoal, but not in control animals. A progressive rise in leucocyte count was found after successive haemoperfusions, but levels returned to normal 21 days after their initial operative procedure. Platelet counts fell after charcoal haemoperfusion, but returned to within normal levels before the next perfusion.

Paraquat suicide in a young woman: results of therapy directed against the superoxide radical

The clinical course of a young woman following two separate suicide attempts using the herbicide paraquat is reported. The patient survived an intramuscular injection of paraquat almost asymptomatically, but later exhibited a typical fatal course with fulminant proliferative pulmonary fibrosis after an intravenous injection. Fibrosis and death occurred despite a therapeutic regimen based upon a known action of paraquat, the generation of superoxide (O(2)[unk]), using superoxide dismutase, α-tocopherol, and ascorbic acid in conjunction with forced diuresis and prednisone. While treatment failed explanations for the failure of therapy in this case and current therapeutic alternatives are discussed so that they may be considered when future cases are encountered.

Efficacy of gut lavage, hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents. Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1-2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1-2 ppm, the clearance values for hemoperfusion were some 5-7 times higher than those for hemodialysis. In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquats less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.