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: 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 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: 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.

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 ion 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 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 ion 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: Inclusions in a liquid flow, such as air bubbles in a blood flow, are detected by transmitting a signal through the fluid and receiving and interpreting the received signal based on the expected degree of attenuation for the liquid and the inclusions. The amplitude of the transmitted signal is automatically adjusted to maintain a constant average amplitude of the detected signal, thus compensating for changes in the detection environment. The average amplitude of the transmitted signal is controlled by integrating the received signal using an integrator with a time constant longer than the time constant of the expected inclusion signals, and comparing the integrated signal to a constant reference level.The presence of microbubbles is detected and a signal comprising a string of high frequency pulses is generated while the microbubbles are present.

Abstract: An insulating sleeve retains heat in the plastic of a flexible plastic medical tube when the plastic of the medical tube is dielectrically heated by a radio frequency tubing sealer. The heat retained by the insulating sleeve permits additional melting of the plastic of the medical tube after a seal has been formed. The additional melting results in forming an easily tearable web between the segments of the medical tube in the same operation as the sealing operation. The medical tube is selectively sealed without forming the easily tearable web by using the radio frequency tubing sealer without the insulating sleeve.

Abstract: A fluid sampling method in which a variable volume chamber between a needle site and a syringe creates a negative pressure at the tip on its removal from the needle site to reduce the exposure to liquid at the time of removal.

Abstract: A method and apparatus for interconnecting electronic circuit boards through the use of twisted wire jumpers which are formed from multifilament wire and which have enlarged bird cages formed along the pins. The pins are drawn through a stack of circuit boards to position the cages in contact with interconnection apertures located in the printed circuit boards. The frictional engagement of the cages in the apertures provides both electrical inter connection of, and mechanical coupling between the printed circuit boards.

Abstract: Coagulation related activities are detected in a fluid sample in a plunger sensor cartridge. The cartridge includes a test cell with a reagent chamber and a reaction chamber and a plunger assembly. A reagent drive subassembly forces the contents of the reagent chamber into the reaction chamber. The plunger assembly is raised and released by a plunger lifting subassembly to allow it to descend through the sample of liquid in the bottom of the reaction chamber. A dispenser subassembly automatically meters precise quantities of fluid into the test cells. The plunger lifting subassembly and the reagent drive subassembly are mechanically separate and are controlled separately. Stepper motors are used to provide precise control over the degree, rate and sensitivity of movement of the plunger lifting subassembly, the reagent drive subassembly and the dispensing subassembly.

Abstract: A method and apparatus for generating lubricant at the head/disk interface throughtout the life of a disk drive utilizing friction at the slider/disk interface to activate the polymerization of a monomer at the catalytic surface on the slider and/or the disk surface. The monomer is supplied to the catalytic surface through the vapor state from a reservoir.

Abstract: A cooling system employs a cooling liquid and a cooling gas in a combined thermodynamic cycle to overcome the flow resistance of dense assemblies of heat generating components and to improve heat transfer by inducing turbulence, thereby reducing the effects of thermal hysteresis and boundary layer formation. Sensible heat gain to the cooling liquid and gas and latent heat of vaporization of the cooling liquid also occur in channels through and over the components. The flow of cooling gas propels the cooling liquid through the channels. The cooling system is advantageous for cooling electronic components such as integrated circuits which exhibit relatively high degree of energy and physical density, in supercomputers. The cooling system may also be advantageously combined with an immersion cooling system for the power supply components in the computer.

Abstract: A method and apparatus for interconnecting electronic circuit boards through the use of twisted wire jumpers which are formed from multifilament wire and which have enlarged bird cages formed along the pins. The pins are drawn through a stack of circuit boards to position the cages in contact with interconnection aperture located in the printed circuit boards. The frictional engagement of the cages in the apertures provides both electrical interconnection of, and mechanical coupling between the printed circuit boards.This application is a division of co pending patent application Her. No. 07/347,507, filed May 4, 1989, now U.S. Pat. No. 5,014,419, issued May 14, 1991, U.S. Pat. application Ser. No. 07/347,507 was a continuation-in-part of application Ser. No. 07/053,142, filed May 21, 1989, now U.S. Pat. No. 5,054,192, issued Oct. 8, 1991. All of these applications and patents are assigned to the same assignee.