Centrifugal fluid pump assembly

A centrifugal fluid pump assembly comprising

• a housing having a blood inlet port and a blood outlet port;
• centrifugal fluid pump section including an impeller having a magnetic material disposed therein, the impeller being rotatable within the housing without contacting the housing for feeding a fluid by a centrifugal force developed during rotation of the impeller;
• an impeller rotational torque generating section including a rotor and a motor for rotating the rotor, the rotor having a magnet for attracting thereto the magnetic material of the impeller;
• an impeller position control section having an electromagnet;
• a controller for changing the floating position of the impeller inside the housing using the impeller position control section, for measuring electric current for driving the motor, and for calculating a fluid viscosity based upon a variation in an amount of the motor-driving electric current obtained by changing the floating position of the impeller;
• and
• wherein the controller stores relational data relating to a discharge flow rate and calculates a discharge flow rate using an actual value of the motor-driving electric current, an actual number of rotations of the motor, the fluid viscosity calculated by the controller, and the relational data or a relational expression data.