Abstract: A user interface for a medical instrument such as a dialysis machine is described which uses both a touch screen and at least one hard key off of the touch screen to effectuate a change in a parameter associated with the operation of the machine or the treatment session. The user interface is connected to a central computer control system having a host microprocessor and a backup safety microprocessor. The hard key is directly wired to the safety microprocessor. After the user selects a new parametric value on the touch screen, the user presses a hard key. The host and safety microprocessors implement a verification routine to insure that the entered parameter is appropriate for the patient's treatment and the display on the touch screen. If the verification procedure ends in a positive result, the user is prompted to presses a second hard key to confirm the change, causing an additional verification check to be preformed.

Abstract: A method for flushing and filling of an extracorporeal blood circulation system of a dialysis machine is disclosed. The machine has a dialyzer, a separate dialysis liquid circuit flowing through a dialysate side of the dialyzer with the extracorporeal blood circulation system flowing through a blood side of the dialyzer for removal of impurities from the blood and the dialysate and blood sides of the dialyzer separated by a hemodialyzer membrane. The method comprises the steps of transporting dialysis liquid from the dialysis liquid circuit in the dialysate side of the dialyzer through the hemodialyzer membrane into the blood side of the dialyzer and the extracorporeal blood circulation system to flush and fill the system and conducting a dialysis treatment.

Abstract: Several tests are described for verifying the integrity of the extracorporeal circuit of a medical instrument, such as a dialysis machine. One test verifies the condition of the blood tubing set. Another test verifies that the clamps in the arterial and venous lines adequately occlude the arterial and venous lines. Another test confirms that the arterial and venous lines are properly installed on their respective ports for receiving the lines after the treatment session has ended. In this last test, a fluid such as heated water is then introduced into one of the arterial or venous lines and sent out of the line through its respective port, where it is detected with suitable fluid detection equipment such as a thermistor. The heated fluid and thermistor verify that the arterial line is connected to its arterial port and the venous line is connected to its venous port and that there is an unobstructed fluid path in the blood tubing set.

Abstract: A method for withdrawing priming fluid from the extracorporeal circuit of a dialysis machine is described which substantially prevents return of the priming fluid back to the patient. In accordance with the method, priming fluid is drawn from the extracorporeal circuit through the dialyzer membrane and into the dialysate circuit. Blood is introduced into the extracorporeal circuit as the priming fluid is withdrawn through the dialyzer. Withdrawal of the priming fluid may be accomplished by pumping the blood pump in the forward direction at a first rate and operating a pump in the dialysate circuit at a second rate. Valves in the dialysate circuit are operated such that the pump in the dialysate circuit draws priming fluid across the dialyzer membrane into the dialysate circuit, and thereby prevents the priming fluid from being returned to the patient.

Abstract: A method for raising or lowering the fluid level in a chamber in an extracorporeal circuit of a dialysis machine, such as an air trap or compliance chamber, is provided which uses a touch screen. The user of the machine is prompted to indicate on the touch screen the current or actual level of fluid (e.g., blood) in the drip chamber. The user then touches the touch screen to indicate the level, such as by touching an illustration of the chamber at a level corresponding to the actual level. The control system for the machine determines from the level indicated on the touch screen whether the level in the chamber needs to be raised or lowered, and by how much, and responsively operates chamber level adjustment apparatus (such as pressure adjustment apparatus in air communication with the chamber) to raise or lower the level closer to the proper level.

Abstract: A user interface for a medical instrument such as a dialysis machine is described which uses both a touch screen and at least one hard key off of the touch screen to effectuate a change in a parameter associated with the operation of the machine or the treatment session. The user interface is connected to a central computer control system having a host microprocessor and a backup safety microprocessor. The hard key is directly wired to the safety microprocessor. After the user selects a new parametric value on the touch screen, the user presses a hard key. The host and safety microprocessors implement a verification routine to insure that the entered parameter is appropriate for the patient's treatment and the display on the touch screen. If the verification procedure ends in a positive result, the user is prompted to presses a second hard key to confirm the change, causing an additional verification check to be performed.

Abstract: A dialysis machine is described which has a batch dialysate preparation system comprising a lightweight, substantially noncompliant dialysate tank and volumetrically closed dialysate circuit. The tank is made from a polymeric material, such as polypropylene, with fiberglass windings on the exterior of the tank. The noncompliance of the tank and dialysate circuit allows for greater control over ultrafiltration of the patient.

Abstract: Water treatment and pretreatment methods and processes for use in a dialysate preparation machine are described. In one aspect, water is passed through a first filter having chlorine removal properties and then passed into a line. Water is removed from the line at a sample location. The removed water is periodically sampled for the presence of chlorine or chloramines. The presence of chlorine or chloramines indicates that the filtration capacity for chlorine of the first filter is substantially exhausted. The method further includes the step of filtering the water downstream from the sample location in a second filter having chlorine removal properties, and replacing the first filter if chlorine or chlorine is detected during the sampling step. Water pretreatment may be provided by mixing hot and cold water from a source with a temperature-controlled mixing valve and passing the water through the first filter, so as to provide warm, filtered water to the dialysate preparation machine.

Abstract: Methods and apparatus for increasing the accuracy of ultrafiltration in a dialysis machine and decreasing the time required for dialysis. The machine inclused a substantially non-compliant tank for mixing and storing a batch of dialsyate. In a preferred form, the tank is a hollow vessel made from a lightweight and chemically inert material, such as polypropylene, reinforced on its exterior. The machine further includes an ultrafiltration pump for pumping fluid from an extracorporeal circuit to an ultrafiltration tank commensurate with the removal of water from the patient. The pump is calibrated with the volume of fluid in the tank.

Abstract: A method is described for determining the sodium clearance of a dialyzer. Dialysate containing sodium ions is circulated through the dialysate side of the dialyzer. Water is continuously circulated through the blood side of the dialyzer, the water being single passed through the blood side of the dialyzer. Measurements of the conductivity of the dialysate are made prior to the dialysate entering the dialyzer, and measurements of the conductivity of the dialysate are made after the dialysate has passed through the dialyzer. The clearance of the sodium ions by the dialyzer is calculated from the measurements of conductivity. The measurements of conductivity of the dialysate after passing through the dialyzer becomes substantially constant as the dialysate and water are circulated through the dialyzer. The sodium clearance corresponds to urea clearance of the dialyzer, since the two molecules are approximately the same size.

Abstract: A hemodialysis machine has ports of a disinfection manifold for receiving the arterial and venous line connectors terminating the arterial and venous lines. The ports are in fluid communication with a hydraulic system that circulates disinfection fluid through the machine including the extracorporeal circuit. The ports are constructed so as to provide a gap extending circumferentially around the arterial and venous line connectors. When the disinfection fluid circulates through the ports of the disinfection manifold, the fluid circulates around the external surfaces of the connectors as well as through the internal fluid passages, thereby insuring a complete disinfection of the connectors.

Abstract: A loading platform and chemical addition system are described for a machine that prepares a batch of dialysate. The loading platform is in fluid communication with a dialysate preparation tank, and receives chemical vessels that contain a batch quantity of dialysate chemicals. The chemicals are released from the vessels automatically and fall onto a shelf in the loading platform. Nozzles and spray equipment are provided for insuring the complete release of the chemicals from the vessels and their dispersion into the tank. Novel mixing techniques are implemented in the tank to insure complete mixing of the dialysate solution and prevention of settling of dialysate solution at the bottom of the tank.

Abstract: A method is described herein for automatically rinsing blood back to a patient. The method comprises the steps of pumping dialysate (or, alternatively, saline solution) through a dialyzer into an extracorporeal circuit, and pumping blood in the extracorporeal circuit out the arterial and venous lines back to the patient. Optical sensors monitor the concentration of blood in the arterial and venous lines as the blood is being pumped from the extracorporeal circuit back to the patient. The return flow of blood is ceased when the concentration of blood in the arterial and venous lines drops to a predetermined threshold level, thereby preventing excess fluids from being returned to the patient.

Abstract: A method is described for automatically testing the integrity of a dialyzer filter within a dialysis machine. The method consists of substantially removing fluids which may be present from the blood side of the dialyzer filter, pumping air into the blood side of the dialyzer filter with a blood pump to pressurize the dialyzer filter, and measuring the pressurization of the dialyzer filter. If the dialyzer filter pressurizes, the rate of decay of pressurization is measured. The pressurization and rate of decay are indicative of the integrity of the membrane of the dialyzer filter.

Abstract: A vessel storing a batch of chemicals for delivery into a dialysate preparation tank includes a machine readable indicator, permitting automatic identification of the contents of the vessel prior to operating the vessel and introduction of chemicals into a tank where the dialysate solution is mixed. Various types of machine-readable indicators may be used, such as, for example, "touch" memory buttons, bar codes, or magnetic strips. Suitable reading devices for the machine-readable indicators are provided for reading the contents of the bottle.

Abstract: High level disinfection of a home hemodialysis machine is achieved without the use of disinfection chemicals. The machine has a water treatment module, an extracorporeal circuit and a dialysate circuit. Purified water is heated to a high level disinfection temperature, such as 75 or 80 degrees C. The water is circulated though the water treatment module, the extracorporeal circuit and the dialysate circuit for a time sufficient to achieve a high level disinfection of the machine, for example at least one hour. After the high level disinfection is obtained, the water is drained from the machine and the machine is placed in condition for another treatment session.

Abstract: A method for maintaining separation of old and new dialysate in a dialysate preparation tank is disclosed. The new dialysate is stored in the tank at a first temperature and withdrawn from the bottom of the tank. The dialysate is circulated through a dialyzer, and then returned to the tank at the top of the tank at a higher temperature in a substantially non-turbulent manner. The temperature differential between old and new dialysate and the manner of withdrawing and reintroducing the dialysate to the tank cooperate to form discrete zones of old and new dialysate without substantial mixing of the dialysate in the two zones.

Abstract: A dialysis machine is disclosed that incorporates a water treatment module, a dialysate preparation module having a dialysate circuit, and an extracorporeal circuit including a dialyzer and arterial and venous blood lines that connect to the patient. The machine accomplishes on-line disinfection of all the fluid circuits of the machine, including the water treatment module, the dialysate preparation module and extracorporeal circuit, the arterial and venous lines, and the dialyzer, by circulating water heated to a high level disinfection temperature (e.g., 80 degrees C.) through the fluid passages of the machine for a sufficient time (such as an hour) to achieve high level disinfection. After the dialysis session is ended, the patient connects the arterial and venous lines to ports in a disinfection manifold that places the arterial and venous lines into fluid communication with the heated water. Thereafter, the machine is ready to disinfect the fluid circuits including the extracorporeal circuit.