A system and method for controlling extracorporeal blood flow in a patient. The system includes a blood pump having a rotor, a plurality of rollers carried by the rotor and a pump chamber extended in tension about the rollers. A sensor measures an operating parameter of the blood pump and a controller, coupled to the sensor, calculates the flow efficiency of the blood pump based on the measured operating parameter. The controller is further configured to display the flow efficiency on the display device, and the operation of the blood pump is adjusted based on the flow efficiency when necessary.
