Abstract: A centrifugal pump for pumping biological fluids such as blood includes a housing which defines a pumping chamber. The pumping chamber encloses an impeller comprised of a spindle for rotation about a spindle axis and a plurality of blades positioned such that each inner blade end is positioned adjacent to the spindle. The plurality of inner blade ends forms a spin inducer which aids in decreasing hemolysis.

Abstract: A system of processing blood during a surgical procedure includes a centrifugal blood pump with an inlet and an outlet, a means for oxygenating the blood and a means for recirculating a portion of the oxygenated blood to the inlet of the blood pump. The volume of blood recirculated through the system can be controlled by a flow control means. Recirculation of a portion of the blood reduces the cost and size of the system.

Abstract: A centrifugal pump for pumping biological fluids such as blood includes a housing which defines a pumping chamber. The pumping chamber encloses an impeller mounted on a spindle. The impeller carries coupling mechanisms which couple with an external source of rotation to rotate the impeller. The spindle allows the impeller to rotate freely, but both ends of the spindle are constrained in the axial and lateral directions. The housing includes an inlet and an outlet.

Abstract: A disposable pumping unit has a pump housing which encloses a pumping chamber therein. The pump housing includes an inlet and an outlet communicating with the pumping chamber. A stator is connected to the pump housing and has a distal end which extends into the pumping chamber. The stator defines a central axis. A bearing is supported at the distal end of the stator and is aligned with the central axis. Positioned within the pumping chamber is a rotator supported on the bearing for rotation about the central axis. At least one magnet is carried by the rotator.

Abstract: A combined blood reservoir/pump for heart/lung bypass surgery includes a chamber having an upper reservoir chamber and a lower pump chamber with a passage connecting the reservoir chamber and the pump chamber. An inlet positioned adjacent an upper end of the housing supplies blood to the reservoir. An impeller is positioned in the pump chamber and is driven by a shaft which has its lower end connected to the impeller and an upper end connected to a drive motor which is mounted near the top end of the housing. An outlet is connected to the pump chamber for supplying blood from the combination blood reservoir/pump.

Abstract: A disposble centrifugal pump has two parts. One part includes a blood pumping chamber and a driven impeller, while the second part includes an impeller drive to which the impeller is coupled by mechanical shaft couplings. Two seals are provided to limit exposure of the fluid being pumped to possible contaminants. The first seal provides an effective shaft seal around the impeller shaft as it leaves the pumping chamber. The second seal provides an effective seal about all outer portions of the shaft when the shaft is coupled to the impeller drive to limit migration of possible contaminants along the shaft and into the pumping chamber.

Abstract: Blood flow rate in a motor driven centrifugal blood pump is measured indirectly and non-invasively by sensing a first parameter representative of pump RPM and a second parameter representative of motor torque. The blood flow rate is computed as a function of the first and second parameters. By measuring the second parameter in a zero flow condition while the motor is being driven at a known RPM, a viscosity calibration factor is determined which is used, together with the first and second parameters in the calculation of flow rate.

Abstract: A heart/lung bypass system having a centrifugal blood pump driven by a motor detects reverse flow conditions in which blood is flowing from the load to the pump outlet. An alarm control provides an alarm signal based upon a flow magnitude signal, a pump speed (rpm) signal, and a torque signal. When the pump is at a desired initial speed and an arterial flow line from the pump is unclamped, a decrease in torque requirements indicates a reverse flow condition, and an alarm is initiated. Reverse flow conditions are also indicated by an increase in rpm followed by a decrease in flow magnitude, and by a decrease in rpm coupled with an increase in flow magnitude. In addition, when the pump is running at a constant rpm, an increase in flow magnitude followed by a decrease in torque indicates a reverse flow condition, and an alarm is sounded.

Abstract: An ultrasonic Doppler flow measurement system for measuring blood flow in a polymer conduit includes an ultrasonic transmitter transducer, an ultrasonic receiver transducer, an amplifier/detector circuit for producing a Doppler signal which varies in frequency as a function of blood velocity, a clipping circuit, an automatic gain control circuit, and a frequency-to-voltage converter which produces an output signal having a voltage which is a function of flow velocity. The automatic gain control circuit accomodates variations in Doppler signal strength due to varying red blood cell concentration. The clipping circuit prevents an inordinate reduction of gain by the automatic gain control circuit due to extremely large, occasional gas bubbles or fat globules in the blood.

Abstract: A centrifugal blood pump has a face seal between a pump housing wall and a hub of an impeller which provides upon assembly a gas permeable seal at a seal interface surrounding a shaft defining the rotational axis of the impeller. This seal separates a blood pumping chamber from a separate chamber housing lubricants and bearings for impeller rotation. Prior to rotation of the impeller, the blood pump is sterilized by exposure to ethylene oxide gas which passes through the gas permeable seal interface to also sterilize the interior of the bearing chamber in the pump. Upon rotation of the impeller, the seal interface, which is perpendicular to the axis, is converted to a gas and liquid impermeable seal.

Abstract: A centrifugal blood pump has a tapered seal between a pump housing wall and a hub of an impeller which provides a fluid tight seal interface surrounding a drive shaft which is connected to the impeller and which extends through the pump housing wall. The tapered seal has a maximum radial dimension adjacent to the wall and a minimum radial dimension adjacent the hub so that air bubbles (which seek the smallest shaft diameter) will not insulate the seal interface edges from fluid flow. The seal interface, which is perpendicular to the drive shaft axis, is located in a high flow area between the wall and the hub to increase cooling effects.

Abstract: A centrifugal blood pump has an impeller with a hub, a blade support ring and alternating long and short blades. A tapered seal between a pump housing wall and a hub of an impeller which provides a fluid tight seal interface surrounding a shaft. The long blades of the impeller have rear edges which are closer to the wall than is the seal interface and inner edges which extend from the rear edges to the hub. This provides high flow in the vicinity of the seal interface to enhance heat dissipation from the seal interface.