Abstract: The invention provides an apparatus for preparing a fluid for a medical procedure by mixing of at least one medicament in the form of powder with water, the medicament is held in a vessel which defines a bottom, a side wall, and a top opening which is closed by an membrane for sealing the inside of the vessel. The apparatus includes an opener for opening the membrane of the vessel.

Abstract: The present invention constitutes dialysate formulations that are suitable for use in preparing dialysate solutions for use in batch and/or proportioning systems and for improving dialysis efficiency by reducing or preventing clotting of the dialysis flow paths. The dialysate chemical formulations for one batch of dialysate comprise an acid concentrate stored in a first vessel, and a citrate-containing bicarbonate concentrate stored in a second vessel. The contents of the first and second vessels are emptied into a dialysate preparation tank and mixed with water to form a batch quantity of dialysate solution. Alternately, a dry acid and/or a dry citrate-containing base concentrates are dissolved separately in measured quantities of water to form liquid concentrates which are then used in conjunction with a proportioning machine to generate on-line a final dialysis solution stream.

Abstract: A method and control system computing platform for a dialysis machine that uses Symmetric Multi-Processing (SMP) architecture. The SMP architecture tightly couples multiple (e.g., 2) independent processors by sharing memory between the processors. A single shared memory is used by both processors in order to facilitate communication between the processors and reduce cost by eliminating the expense of redundant memory. In this way, the two, or in general “N” processors, increase processor throughput by allowing the execution of N processes in parallel while without requiring extra memory and without having a single point of failure in the computer. In the event of a bus failure on the circuit card, the computer is reset using distributed hardware watchdogs. The watchdog reset signal is also sent to the hardware components of the dialysis machine in order to place the system in a safe.

Abstract: A method of calibrating a pump that is subject to variations in flow rate based on inlet pressure variations, such as a peristaltic pump found in medical instruments. The pressure at the inlet of the pump is measured and recorded during prior uses of the pump. A mean or average inlet pressure is derived from the measurements, either directly or indirectly from the measurements of using regression techniques, as a way of forecasting the inlet pressure during the next use of the pump. The pump is then calibrated at an inlet pressure that is set or adjusted to match the mean or average inlet pressure. The calibration is thus accurately performed for the pump, and is independent of the absolute accuracy of the inlet pressure sensor.

Abstract: A set of bottles for containing dialysate chemical formulations, chemical cleaning agents or the like is described. The chemical formulation bottles come in two varieties, sodium bicarbonate and liquid acid formulations, each bottle having a slightly different shape. The different shapes cooperate with a bottle mounting structure in the dialysis machine to insure that bottles are correctly installed on their respective bottle opening mechanism. The bottles also have a detection feature comprising either a raised rim or groove extending around the periphery of the bottle. A sensor assembly in the bottle mounting and opening system detects the detection feature. The detection feature is used by the machine to distinguish between dialysate formulation bottles and chemical cleaning bottles, which do not have the detection feature. The detection feature prevents unintentional installation of the chemical bottle on the opening mechanism for the dialysate chemical formulation bottles.

Abstract: A method of calibrating a dialysis machine to determine the volume of a dialysate flow path of the machine including a dialysate preparation tank includes the steps of introducing a known quantity of electrically conductive chemicals into the dialysate preparation tank, filling the dialysate solution flow path with water, mixing the chemicals with water to form a solution, measuring the conductivity of the solution, calculating the system volume (Vsys) according to the relation: Vsys=M/(a1r+b1) where M is the mass in grams of the chemicals, a1 and b1 are a coefficient of linearity and a constant of linearity, respectively, for the chemicals and r is the measured conductivity of the solution.

Abstract: A method of disinfection of a dead-ended fluid line in a medical instrument such as a dialysis machine is described. The method comprises introducing a heated fluid into the fluid line, allowing the fluid to remain in the line for an experimentally determined optimal dwell period, removing the fluid from the fluid line, and then repeating the cycle for a time period sufficient to achieve a disinfection of the fluid line. The optimum dwell period and frequency for exchanging the heated fluid is determined so that the heated fluid is left resident in the line to exert a cidal effect but not so long that the it cools to the point of being ineffective, nor changed so frequently that that the time spent with no hot water resident in the line begins to detract (e.g., unduly prolong) the disinfection process.

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 batch of dialysate solution is made from a mixture of bicarbonate formulation and a liquid acid formulation. The liquid acid formulation is introduced into a dialysate tank and then removed from the tank and stored elsewhere, such as in an ultrafiltration tank, where it is diluted with a few litres of water. The dialysate tank is then filled with water and the bicarbonate formulation is added to the dialysate tank. The bicarbonate formulation is mixed and dissolved by circulation in a closed loop, with the liquid acid formulation kept separate. When the bicarbonate solution has been prepared, the liquid acid solution and the bicarbonate solution are mixed together and stored in the dialysate preparation tank. An additional quantity of dilution water is introduced into the dialysate system to bring the final conductivity down to the desired range. The excess dialysate solution can be used for several purposes, such as an endotoxin flush of the blood tubing set or a dialyzer clearance test.

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 of adjusting the final conductivity of a batch of dialysate to bring the conductivity down to a desired level is described. The batch of dialysate is prepared by mixing excess quantities (e.g., 5%) of dialysate solution chemicals with water to form a solution with a conductivity greater than that required for the particular batch. A measurement of the dialysate solution is taken. A precise volume of water is added to the dialysate solution to dilute the dialysate to the proper level. The precise volume of water is calculated from a known or estimated total system, the desired conductivity level and the actual conductivity. The resulting diluted dialysate is at the desired conductivity level. Excess dialysate which may be present in the dialysate circuit or associated tanks is then flushed to a drain. In a hemodialysis embodiment, the excess dialysate may be flushed through the dialyzer into the blood lines to rinse any pyrogens from the extracorporeal circuit.

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 hemodialysis machine is described that has an extracorporeal circuit that is primed automatically prior to connection of the patient to the machine. The priming is accomplished by filling the extracorporeal circuit with a priming fluid, such as a saline or dialysate solution or blood. The blood pump and clamps in the arterial and venous lines are operated by a control system in a fashion to create multiple brief pressure pulses in the priming fluid. The pressure pulses shear air bubbles present on the blood side of the dialyzer membrane off the membrane. The blood pump is then operated to clear the bubbles from the dialyzer compartment where they are removed from the priming fluid by conventional bubble trap apparatus.

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.