Comparison of a new and a standard single-needle dialysis system using a mathematical model.

Two single-needle dialysis systems are compared for their hydrodynamic and kinetic behavior, the classic double-headed pump system and a newer bidirectional blood pump. First, discharges and pressures are calculated in a time-space grid to learn about the flow characteristics of the single-needle systems. These parameters are important for they control ultrafiltration and clearance rates in the artificial kidney. Also, the influence of different artificial kidneys and expansion chambers on the flow parameters is studied. Second, starting from these results, the removal of urea and creatinine is simulated using a double-pool model for both a normal dialysis session and an ultrashort daily autodialysis. As a result, the use of a single marker molecule to study or characterize solute removal is questioned. The new blood pump is able to perform dialysis filtering equivalently to the classic system but has its own specific advantages.