Blood purification apparatus

A method executed by a blood purification apparatus including

• a blood circuit which is coupled with a puncture needle punctured into a patient and through which blood from the patient flows,
• a blood pump that is provided to the blood circuit and delivers liquid in the blood circuit by being driven,
• a needle removal detector that detects removal of the puncture needle from the patient,
• a dialysate introduction circuit that introduces dialysate into the blood circuit in the blood return process, and
• an air introducer that pushes out the dialysate introduced in the blood circuit by introducing air into the blood circuit in the blood return process, the method comprising the steps of:
• detecting removal of the puncture needle;
• starting a blood return process to return the blood in the blood circuit to the patient;
• determining whether to end a dialysate introduction stage to introduce the dialysate into the blood circuit based on an amount of returned blood and/or elapsed time;
• starting an air introduction stage to introduce the air into the blood circuit in response to determination that the dialysate introduction stage ends;
• and
• putting the blood pump in a non-active state in response to determination that the blood return process ends.