Blood purification apparatus

A blood purification apparatus comprising:

• a blood circuit including an arterial blood circuit and a venous blood circuit and through which blood of a patient is allowed to extracorporeally circulate;
• a blood purification device connected to the arterial blood circuit and to the venous blood circuit and that purifies the blood circulating through the blood circuit;
• a dialysate introduction line that allows dialysate to be introduced into the blood purification device;
• a dialysate drain line that allows waste liquid to be drained from the blood purification device;
• a liquid-delivering device extending between and connecting the dialysate introduction and the dialysate drain line, wherein the liquid-delivering device is capable of delivering liquid such that a volume of the dialysate to be introduced into the blood purification device and a volume of the waste liquid to be drained from the blood purification device are substantially equalized;
• an ultrafiltration pump capable of removing, through the blood purification device, water from the blood circulating through the blood circuit,
• an ultrafiltration line comprising:
• a first end of the ultrafiltration line connected to the dialysate introduction line at a position on a downstream side with respect to the liquid-delivering device and
• a second end of the ultrafiltration line connected to the dialysate introduction line at a position on an upstream side of the liquid-delivering device with the ultrafiltration pump located between the first end and the second end, and
• a control device in communication with the ultrafiltration pump and the liquid-delivering device;
• wherein the ultrafiltration line is connected with the ultrafiltration pump and the ultrafiltration pump is controllable by the control device to perform ultrafiltration by drawing the dialysate in the dialysate introduction line through the ultrafiltration line and the control device is configured to control the ultrafiltration pump so that the volume of the dialysate to be introduced into the blood purification device becomes smaller than the volume of the waste liquid to be drained from the blood purification device;
• wherein the liquid-delivering device and the ultrafiltration pump are in communication with the control device and the control device activates the liquid-delivering device and the ultrafiltration pump so that each are capable of delivering liquid by periodically causing suction to take in the liquid and discharge to move out the liquid;
• wherein the control device is configured to control the ultrafiltration pump to operate only in a period when the liquid-delivering device is undergoing the discharge, and
• wherein the control device is operable to control the ultrafiltration pump so that a pressure of liquid discharge during the discharge by the liquid-delivering device exceeds a predetermined value so that the dialysate is prevented from flowing backwards.