Blood purification device

A blood purification device, comprising:

• a blood circuit for extracorporeally circulating blood of a patient;
• a liquid supply line for supplying a supply liquid, being a non-blood liquid, to a blood purifier provided on the blood circuit or to the blood circuit, wherein the supply liquid is supplied from a storage bag located upstream of the liquid supply line;
• a peristaltic liquid supply pump provided on the blood circuit or on the liquid supply line;
• a peristaltic waste liquid pump provided on a waste liquid line, the waste liquid line being separate from the blood circuit, through which a waste liquid is discharged from the blood purifier;
• a water balance amount detection unit for detecting a water balance amount of the supply liquid and the waste liquid, wherein the water balance amount detection unit comprises:
• a supply liquid subdivision chamber, temporarily storing the supply liquid, being provided on the liquid supply line so that the supply liquid is supplied from the storage bag and flows toward the blood purifier,
• a waste liquid subdivision chamber being provided between a first end and a second end of the waste liquid line downstream of the blood purifier and temporarily storing the waste liquid,
• a weight detection mechanism capable of detecting a total weight of the supply liquid subdivision chamber and the waste liquid subdivision chamber, and
• a change amount calculation unit for calculating an amount of change in weight detected by the weight detection mechanism;
• and
• a water balance amount control unit that corrects one or both of a pump speed of the peristaltic liquid supply pump and the peristaltic waste liquid pump so that the water balance amount detected by the water balance amount detection unit matches a target water balance amount,
• wherein the water balance amount control unit is configured to correct the pump speed so that the amount of change in the weight calculated by the change amount calculation unit matches an amount of change in weight resulting in the target water balance amount;
• wherein the water balance amount control unit is configured to be able to switch between a first correction condition for correcting the pump speed on every water balance amount detection and a second correction condition for correcting the pump speed based on a plurality of water balance amount detection results, and
• wherein the water balance amount control unit performs pump speed correction under the first correction condition at a beginning of treatment and switches to pump speed correction under the second correction condition when a stability determination condition for determining that the water balance amount is stabilized is satisfied.