Abstract: A hemodiafiltration system which enables concurrent performance, in a single system, of hemodialysis and hemofiltration includes a dialyzer, consisting of a casing and at least one semipermeable membrane accommodated therein for dialyzing and purifying body fluid such as blood, plasma, etc., through contacting of the body fluid and dialyzate via the semipermeable membrane, and pumps for causing the dialyzate to flow through the dialyzer. A controller repeatedly changes the difference between the inflow amount of the dialyzate into the dialyzer per unit time and the outflow amount of the same from the dialyzer per unit time from a positive value to a negative value and then from negative to positive, whereby the repeated operation of taking or sucking out aqueous component or constituent and accompanying waste molecules from the body fluid followed by infusing or forcing a compensatory amount of dialyzate into the body fluid is made possible.

Abstract: A blood purification apparatus includes an extracorporeal circulation system, a blood purifier provided in the system for purifying blood by dialysis or filtration through a semipermeable membrane, a circulation blood volume measuring instrument for measuring changes in a circulating blood volume within a patient's body, a control section comprising a memory for storing a program for a pattern of changes in the circulating blood volume during blood purification, the program being matched to the condition of a patient, and a regulator connected to the extracorporeal circulation system and the control section, for controlling the circulating blood volume, the regulator being controlled by the control section on the basis of the circulating blood volume measured during blood purification and the programmed amount. In this apparatus, optimum blood purification is carried out while maintaining the circulating blood volume at a prescribed level.