Clinical effects of a polyethylene glycol grafted cellulose membrane on thrombogenicity and biocompatibility during hemodialysis

The biocompatibility and thrombogenicity of polyethylene-glycol (PEG)-grafted cellulose hemodialysis (HD) membranes (PEGC) were investigated in cross-over HD of five HD patients with ordinary cellulose (OC). The PEGC significantly suppressed transient leukocyte and thrombocytopenia, and release of C3a, beta-thromboglobulin and platelet factor 4, in corresponding with the quantity of grafted PEG. HD with PEGC resulted in lower granulocyte elastase production, protein and blood cells adsorption on the membrane surface than those with OC. Minimum heparin in HD with PEGC was three times lower than that with OC, with the thrombin-antithrombin III complex elevation lower than that in HD with OC. The results indicate that the grafted PEG effectively suppresses blood and membrane interaction, thus improving biocompatibility and reducing thrombogenicity in clinical HD.

A new type of low blood flow ECCO2R using a hemodialysis system in apneic states

To perform low blood flow extracorporeal CO2 removal (ECCO2R), the authors developed a device for extracorporeal circulation (ECC) equipped with a dialyzer for the elimination of CO2 as bicarbonate. The major problem with this method was the decrease in blood pH. To control blood pH and clarify the limit of CO2 elimination using this method, a study with apneic dogs was performed. Six anesthetized mongrel dogs were intubated and paralyzed with a muscle relaxant. Vascular access was achieved with a venovenous bypass. ECC was initiated under apneic oxygenation (100% O2, 10 cm H2O continuous airway pressure), and the CO2 concentration in the airway outlet was measured. The CO2 was converted to bicarbonate using systemic infusion of trihydroxy-methylamino methane (THAM), and the generated bicarbonate was removed by hemodialysis. Blood flow rate in the ECC was 15 ml/kg/min, and the duration of ECC was 5 hr. During ECC, the hemodynamic parameters of the dogs were stable, and the PaCO2 remained at about 90 mmHg with a PaO2 above 350 mmHg; CO2 elimination from the airway was negligible.

Efficiency and biocompatibility of a polyethylene glycol grafted cellulosic membrane during hemodialysis

Dialytic efficiency and biocompatibility of a new modified cellulose membrane (NMC) were examined in vitro and clinically. NMC was obtained by grafting polyethylene-glycol (PEG) chains to the membrane surface of ordinary cellulose (OC), and it was expected that the random movement of PEG chains would prevent blood cells and large plasma proteins from coming into contact with the membrane surface, resulting in improving the biocompatibility and thrombogenicity of the membrane. Surface characteristics of NMC were rendered anionic and hydrophilic, however, the activations of complement and platelet systems were clearly suppressed in NMC. Minimum heparin requirement for hemodialysis was significantly lower with NMC than with OC dialyzer. No significant difference in solute and water removal was observed between the two dialyzers. These results indicate that NMC can provide increased biocompatibility and antithrombogenic effect while retaining the essential dialysis efficiency of OC.