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Hemoperfusion is a blood purification technique involving direct contact between blood and adsorbent substances (sorbents). There are three basic kinds of sorbent: activated charcoal, immunoadsorbents, resins. Following our previous experience on charcoal hemoperfusion, a new coated anionic exchange resin for blood purification specifically designed to remove phosphates was experimentally employed in animals. 3 pigs, in which uremia had been surgically induced, underwent 6 extracorporeal hemoperfusion sessions (2 per pig) with a cartridge containing 100 gr of resin. The phosphate clearance proved satisfactory, values being 120 ml/min after 10' and around 80 ml/min after 2 hours. The biocompatibility of the resin and of the coating membrane was satisfactory. The negligible variation in pH and plasma bicarbonate during all sessions confirmed the low absorption by the tested resin of other blood anions competing with phosphate.

A new coated anionic exchange resin for blood purification specifically designed to remove phosphates was experimentally employed in animals. 3 pigs, in which uremia had been surgically induced, underwent 6 extracorporeal hemoperfusion sessions (2 per pig) with a cartridge containing 100 gr of resin. The phosphate clearance proved satisfactory, values being 120 ml/min after 10' and around 80 ml/min after 2 hours. The biocompatibility of the resin and of the coating membrane was satisfactory. The negligible variation in pH and plasma bicarbonate during all sessions confirmed the low absorption by the tested resin of other blood anions competing with phosphate.

The capacity of charcoal to absorb endogenous and exogenous toxins is well established. It removes substances of higher molecular weight than standard dialysis membranes. The regular use of charcoal hemoperfusion as an adjunct to hemodialysis in chronic uremia is a real prospect capable of improving the patient's clinical and laboratory condition and/or reducing the weekly time of treatment. In line with our previous experience, 5 consenting informed patients on regular dialysis treatment from 9 to 35 months (residual creatinine clearance 0-1.8 ml/min, mean diuresis 350 ml) were treated without interruption for 5-8 months according to a schedule including two combined hemodialysis/hemoperfusion procedures instead of the previous three hemodialysis sessions. Patients were on adequate dialysis and their clinical, metabolic and laboratory conditions were stable. In the hemodialysis/hemoperfusion procedure a cartridge containing 150 g of methacrylate-coated activated charcoal with high biocompatibility was inserted in the dialysis circuit in series with a flat plate or hollow fiber dialyzer. Clinical, laboratory and metabolic conditions remained unchanged in all patients despite the one third reduction in dialysis hours per week. The tolerance of treatment was good: platelets, white cells and fibrinogen were unaffected. The marked reduction in weekly time of treatment led to a more satisfactory personal and social rehabilitation, enabling more patients to be treated with the same facilities.

The capacity of activated charcoal to remove toxins from the blood is well established. Its poor biocompatibility, inability to remove urea, electrolytes and water, and high cost have so far been the major objection to a wider use of charcoal with chronic uremic patients. The availability of a charcoal coated by a new highly hydrophilic methacrylate based on membrane enabled us to keep 18 uremic patients on a combined hemodialysis-hemoperfusion schedule for 4-52 weeks. Investigations concerned patients in whom relapsing signs of uremia occurred despite technically adequate dialysis, and other cases where dialysis was both technically and clinically adequate. In the first group of patients, the combined programme led to an improvement of the dialysis resistant clinical signs, while certain positive metabolic effects were also observed. In the second group, the hemodialysis-hemoperfusion treatment allowed a reduction of about 30% in time of treatment per week. Tolerance of the new coated charcoal was good throughout treatment in terms both of biocompatibility and of side effects.

The use of charcoal hemoperfusion in the treatment of chronic renal failure has been proposed and applied by several authors. The availability of coating membranes of increased biocompatibility currently allows a safer and wider use of this purifying technique. It has been recently demonstrated that long-term treatment with combined hemodialysis/hemoperfusion yields an improvement of certain dialysis-resistant uremic signs in patients on regular dialysis treatment, while in selected patients it affords a marked reduction (up to one-third) in the overall time of treatment per week. The tolerance of long-term treatment is good. In line with these findings, a multicenter study has been carried out in Italy with two main aims: (1) to see whether long-term treatment with charcoal hemoperfusion is really safe and substantially free from side effects; (2) to verify in a larger and more varied population of patients whether such long-term treatment actually improves certain uremic signs persisting despite adequate dialysis treatment. A third phase of the multicentric study (reducing the weekly time of treatment) is currently being worked on. Five nephrology and dialysis departments took part in the study: in Bologna, Rome, Chieti, Ancona, and Lecce.

Charcoal hemoperfusion has long been used in chronic uremia as an adjunct or substitute for conventional hemodialysis. In this study a regular combination of hemoperfusion and hemodialysis was used to cut down the weekly substitutive sessions from 3 to 2. Ten RDT patients were treated with the reduced-time schedule for 5-56 weeks. Clinical and metabolic conditions remained stable in all patients and no sign of inadequate treatment appeared. Long-term charcoal hemoperfusion was confirmed to be a safe and risk-free procedure. No change in platelets, white cells, red cells, fibrinogen and other hematochemical parameters were detected.

This paper reports the Authors' 8 year experience in the clinical use of charcoal hemoperfusion as a means to reduce the weekly time of treatment in chronic uremic patients. Two different programmes were applied. Programme A (34 patients) which involved substituting the 3 procedures per week of standard dialysis (4 hours duration each) by 2 procedures of combined hemodialysis and hemoperfusion, again of 4 hours duration each. Programme B (18 patients) which involved substituting the 3 procedures per week of 4 hours duration by 3 procedures of 3 hours each, 2 of combined hemodialysis and hemoperfusion, 1 of conventional dialysis. The net weekly reduction was 33% for Programme A and 25% for Programme B. The efficacy of the two Programmes was evaluated by clinical, hematochemical, nutritional and instrumental parameters.

A new coated charcoal for hemoperfusion in uremia was investigated in 14 patients with end stage renal disease who underwent hemoperfusion or combined hemodialysis-hemoperfusion (39 seances). Investigations concerned removal of small molecules, coagulation and hematological status and amino acids and some hormones equilibrium. Clinical observations were also made in all patients. The methacrylate-coated charcoal enabled the removal of "toxins" up to 5000 daltons and the total solute removal did not significantly differ from previous hemoperfusion systems. However, the new coating membrane showed improved biocompatibility, in terms of clinical side effects and/or platelet and fibrinogen alterations.