Abstract: The biocompatibility of polymeric and metallic articles used in contact with blood can be substantially improved by coating the articles as described. The coating materials are triblock copolymers of the polylactone-polysiloxane-polylactone type. Optimum biocompatibility is provided by a coating of optimum surface concentration. Porous membranes can be coated as described, providing improved biocompatibility of blood oxygenators, hemodialyzers and the like.

Abstract: A flow rate of a fluid flowing in a tube is quantitatively determined by altering the electrical conductivity of the fluid by injection of a bolus of saline. The electrical conductivity of the altered conductivity is measured over the time it takes the altered conductivity fluid to pass a conductivity measuring location. The measured conductivity is integrated over the time it take to pass the conductivity measuring location. The integral is interpreted to determine the flow rate.

Abstract: A dialyzer holder for quickly and securely fastening a variety of different dialyzers in position against a surface of a dialysis machine. The dialyzer holder includes an elongated arm pivotably attached to the dialysis machine. An attachment device for engaging a dialyzer is fixed to the free end of the pivotable elongated arm. The pivotable elongated arm is biased to direct the attachment device toward the dialysis machine, and the elongated arm is of sufficient length to position a dialyzer between the attachment device and the dialysis machine when an operator overcomes the bias force and pivots the arm away from the dialysis machine. The bias on the elongated arm is sufficiently strong to maintain the dialyzer suspended between the attachment device and the dialysis machine, even once the dialyzer is filled with blood and dialysate during patient treatment.

Abstract: A method is disclosed for preparing lyophilized and frozen cells as cytometry standards.

Abstract: Improved elastomeric materials useful for medical and therapeutic device applications, such as penetrable septa, are described. In one aspect, the materials are deeply cleaned with solvent to significantly lower levels of undesirable organics. In another aspect, internally lubricated elastomer compositions compatible for use in medical and therapeutic device applications are provided. The lubricating fluid is present in the composition from about 0.5% to 50% by weight, and is initially substantially homogeneously dispersed in the elastomer. The fluid can be integrated into the elastomer by a solvent infusion method. In another aspect an internally lubricated thermoplastic septum, having an appropriate hardness for resealability with multiple penetrations, is provided.

Abstract: The presence of air bubbles entrained in a liquid flowing through a tube is detected flowing the liquid through a conduit which comprises a conductivity cell with a continuous path configuration. An electrical current is induced in the liquid in the conductivity cell. The electrical current in the liquid in the conductivity cell is sensed and interpreted, a decrease in the electrical current being indicative of the presence of an air bubble in the liquid. The conductivity cell comprises an upstream connection, a downstream connection, and two branches connecting the upstream connection to the downstream connection with a continuous path configuration from the upstream connection to the downstream connection through one of the two branches and returning to the upstream connection through the other one of the two branches.

Abstract: The wear on components in a dialysis machine is analyzed for the purpose of making repair and maintenance decisions. The actual performance of components is used to establish a test value. The test value is compared to a threshold value which represents the limits of normal performance of the component. Each instance where the test value exceeds the threshold value is counted and a maintenance count value is developed. The maintenance count value represents the number of abnormal performance events, and the maintenance count value is used to make maintenance and repair decisions. The test value developed for each component varies according to the type of component. The maintenance count values may be displayed for use by service personnel.

Abstract: The amount of electrical power delivered to a dialysate heater in the dialysis machine is maximized without substantially exceeding a predetermined maximum allowed power consumption for the dialysis machine. The instantaneous power consumed by the machine is measured and compared to the maximum allowed power consumption. The excess of power beyond the instantaneous power consumed up to the maximum allowed power consumption is then made available to the heater. The worst case power consumption limitations of the dialysis machine components do not adversely affect the heat available from the heater. The rate at which dialysis treatments may progress may increase or the time required for dialysis treatments may decrease.

Abstract: Information is entered and validated by the operator of a dialysis machine by converting the entered information into a first form using a first conversion relationship such as ASCII. The information in the first form is next converted into a second form using a second conversion relationship, such as floating point numeric. Thereafter the information in the second form is converted back to the first form using the first conversion relationship. The information in the first form which resulted from the third conversion is displayed for acceptance for rejection by the operator. The multiple sequential conversions indicate the proper functionality of a safety system of the dialysis machine. Displaying the information resulting from sequential multiple conversions assures an opportunity for the operator to evaluate the entries for accuracy. Re-display of the previously entered information repeatedly presents the operator with an opportunity to recognize human-induced errors.

Abstract: An apparatus for producing blood component products. In one embodiment, a plurality of a predetermined type of blood component is harvested from a source of whole blood. At least two on-line yield determination techniques are utilized to determine the yield of the harvested blood components. One is a predetermined yield prediction technique and the second is a predetermined yield monitoring technique, each of which are individually calibrated in relation to a predetermined off-line yield determination technique. The predetermined yield prediction and monitoring techniques each provide the yield of the harvested blood components and each is then utilized to provide a determined yield. Consequently, when the harvested blood components are packaged the determined yield may be associated therewith, thereby providing a blood component product.

Abstract: A graphical operator machine interface for a dialysis machine and a method of graphically programming the dialysis machine involves graphically accessing substantially all typical machine operating and dialysis treatment parameters employed in a typical dialysis treatment, and graphically entering selections with respect to each of the selected parameters. The selections of the individual parameters establish display screens which individually present the selected parameters. The selections of the individual parameters also allow the operator to establish values for those selected parameters. The parameters include those involved for setup of the machine for dialysis treatment, those monitored during treatment, the alarm limits established during the treatment, and parameters which allow the automatic initiation of machine functionality prior to the use of the machine for treatments.

Abstract: A method for producing blood component products. In one embodiment, a plurality of a predetermined type of blood component is harvested from a source of whole blood. At least two on-line yield determination techniques are utilized to determine the yield of the harvested blood components. One is a predetermined yield prediction technique and the second is a predetermined yield monitoring technique, each of which are individually calibrated in relation to a predetermined off-line yield determination technique. The predetermined yield prediction and monitoring techniques each provide the yield of the harvested blood components and each is then utilized to provide a determined yield. Consequently, when the harvested blood components are packaged the determined yield may be associated therewith, thereby providing a blood component product.

Abstract: A method and apparatus for cleaning of a dialysate circuit located downstream of the dialyzer in a dialysis machine is described. The method comprises injecting a cleaning agent into the dialysis machine at a point between the dialyzer inlet port and the downstream dialysate circuit in an amount sufficient to substantially reduce the deposit in said downstream dialysate circuit; permitting flow of the agent towards the downstream dialysate circuit; and substantially preventing flow of the agent toward the dialyzer inlet port. The injection adaptor apparatus comprises an injection connector downstream of a backflow prevention valve, and two flanking tubing connectors. The apparatus is inserted at a point downstream of the dialyzer inlet port, and cleaning agent is injected into the injection connector. An adaptor to facilitate handling of cleaning agent during manual agent injection is also described. Additionally, an automated agent injection apparatus is described.

Abstract: An apparatus for trapping bubbles in blood flowing in a circuit, such as an extracorporeal circuit, includes a housing which defines a substantially vertical chamber having an upper subchamber and a lower subchamber. Blood flowing in a substantially downward direction is introduced into the upper subchamber chamber through a delivery port in a direction substantially transverse to a longitudinal axis of the upper subchamber. A substantially frustoconical deflector is positioned in the chamber opposite and spaced apart from the delivery port. The deflector deflects at least a portion of the blood into the upper subchamber above the deflector. Thereafter, the blood is removed from the chamber out an exit port of the chamber. The deflection and redirection of blood within the chamber provide an opportunity for gases in the blood to separate from the blood in the chamber and also helps prevent stagnation of blood in the chamber which might lead to clotting of the blood.

Abstract: A centrifuge is provided with a mounting arrangement that secures a centrifuge bowl to a turntable in response to centrifugal force generated when the turntable is rotated. The centrifuge includes first and second retainers, one of which is connected to the turntable, while the other is connected to the centrifuge bowl. The second retainer engages the first retainer when the first and second retainers are in an interlocking position to secure the centrifuge bowl to the turntable. A movable arm is provided on the turntable and coupled to the second retainer, the movable arm has a ballast that forces the movable arm and second retainer in a first direction in response to centrifugal force generated by rotating the turntable so that the second retainer is forced into the interlocking position with the first retainer. In one embodiment, a vacuum applied to an opening in the turntable assists in mounting a centrifuge bowl to the turntable.

Abstract: An improved dialysis apparatus and method wherein a dialysis delivery system delivers dialysate to a dialyzer through an external dialysate line with a dialyzer inlet connector and a dialysate waste system removes spent dialysate from the dialyzer through an external spent dialysate line with a dialyzer outlet connector. A bypass block comprises a first bypass block connector adapted to connect to the dialyzer inlet connector and a second bypass block connector adapted to connect to the dialyzer outlet connector and a conduit interconnecting the first bypass block connector and the second bypass block connector with a check valve located intermediate the first and second bypass block connectors and oriented to permit fluid flow only from the first bypass block connector to the second bypass block connector.

Abstract: An apparatus for managing and controlling fluid flow through a plurality of fluid conduits includes a chassis, a plurality of conduit occluders mounted in the chassis, each occluder for association with at least one of the plurality of fluid conduits and each being selectively actuatable between an open position permitting fluid flow through a respective fluid conduit and a closed position obstructing conduit fluid flow. A single actuator is mounted in the chassis, the actuator for adjusting the plurality of occluders between the open and closed positions. A roller cage is also mounted in the chassis for mechanically interconnecting the actuator to the plurality of conduit occluders so that the single actuator is mechanically capable of maintaining one of the plurality occluders in the closed position while maintaining another of the plurality of occluders in the open position.

Abstract: A semiconductive power unit for controlling drive motor speed by controlling the power applied to the motor through a variable or switchable semiconductive control element, such as a Darlington transistor. Electrical power is supplied from a power supply to the variable speed drive motor via the controllable semiconductive device connected to provide a variable impedance branch path between the power supply and the variable speed drive motor. A power dissipation characteristic for the variable impedance branch path is established, wherein current flow therethrough decreases monotonically with increasing voltage across the variable impedance branch path. The circuit establishing the characteristic also provides a feedback signal to the controllable semiconductive device to maintain its operation at the established power dissipation characteristic.

Abstract: A differential conductivity recirculation monitor quantitatively determines the degree of recirculation in a fistula by comparing the conductivity of blood entering the fistula to the conductivity of blood being withdrawn from the fistula. A discrete quantity of a high conductivity marker fluid is injected into the blood entering the fistula, altering the conductivity of the blood entering the fistula. The altered conductivity blood enters the fistula and, if recirculation is present, co-mingles with blood in the fistula, altering the conductivity of the blood in the fistula in proportion to the degree of recirculation. Blood withdrawn from the fistula has an altered conductivity related to the degree of recirculation. Quantitative values of the conductivity of the altered conductivity blood entering the fistula and the conductivity of the blood being withdrawn from the fistula are measured and a difference determined.

Abstract: A tubing set includes at least one fluid conveying tube. The fluid conveying tube has a predetermined outside diameter, and is formed of a material adapted to be dielectrically heated at a sealing location. The insulating sleeve has an inside dimension at least as large as the outside diameter of the fluid conveying tube. The tubular insulating sleeve is positioned in a substantially coaxial relationship with the fluid conveying tube at the sealing location, and has a wall with thickness which insulates the fluid conveying tube to permit sealing the fluid conveying tube, and forming a thin, easily tearable web, by the application of the radio frequency dielectric heating.