Automatic priming method

An automatic priming method, which is performed by rotating a blood pump forward and backward in a blood purification circuit in which a connection portion of an arterial blood circuit and a connection portion of a venous blood circuit are connected to form a circulation circuit in which the blood pump, an arterial chamber, a dialyzer operable to function as a blood purifier, and a venous chamber are arranged in the stated order, the venous chamber being connected to an overflow line having an overflow line valve which is operable for opening and closing said overflow line, a side of the venous blood circuit being provided with a venous blood circuit valve which is operable for opening and closing the venous blood circuit, the arterial blood circuit being connected to a storage container for storing a physiological saline as a priming liquid via a supply pipe continuous with the container at a physiological saline line branch portion located between the blood pump and the connection portion of the arterial blood circuit, the method comprising:

• filling the venous blood circuit with the physiological saline with the blood pump being stopped, the overflow line valve and the venous blood circuit valve being opened, wherein, by a drop pressure in the physiological saline storage container, the physiological saline fills the venous chamber through the physiological saline line branch portion and the venous circuit closing valve, and is discharged together with bubbles through the overflow line and the overflow line valve;
• discharging the bubbles and circulating physiological saline in the venous blood circuit through the overflow line by rotating the blood pump forward at a speed of 100 to 300 mL/min with the overflow line opening valve being opened and the venous circuit valve being closed, such that the physiological saline remains in a line portion from the venous circuit closing valve through the arterial blood circuit and the venous blood circuit to the physiological saline line branch portion, and the physiological saline is sent through the chamber, thereby allowing a part of the circuit from the physiological saline line branch point to the venous chamber to be filled with the physiological saline and bubbles in the blood circuit to be discharged through the overflow line and the overflow line valve;
• rotating the blood pump backward at a speed of 10 to 50 mL/min with the overflow line valve and the venous circuit valve opened, thereby allowing bubbles accumulating in an upper portion of the arterial chamber and an upper portion of the dialyzer to be discharged, and simultaneously allowing the priming liquid to pass through the venous chamber from the venous circuit valve through the blood pump, the arterial blood circuit, and the venous blood circuit, to flow out of the overflow line through the overflow line valve;
• and
• again rotating the blood pump forward with the overflow line valve closed and the venous circuit valve opened to perform circulation from a line extending from a lower portion of the venous chamber through the venous circuit valve, the venous blood circuit, and the arterial blood circuit (L1) to the blood pump (P1), further through the arterial chamber and the dialyzer to the venous chamber, such that fine bubbles existing in a line extending from an upper portion of the arterial chamber accumulate in the upper portion of the arterial chamber, and fine bubbles existing in a line extending from a lower portion of the dialyzer to an upper portion of the venous chamber accumulate in the venous chamber.