DE3022200A1 - DIALYSIS MACHINE FOR USE WITH A DIALYSIS DEVICE OF AN ARTIFICIAL KIDNEY AND METHOD FOR DETERMINING THE ULTRAFILTRATION RATE IN SUCH A DIALYSIS DEVICE - Google Patents

Description

dr. V. SCHMIED-KOWARZIK · dr. P. WEINHOLD · Munich C. DANNENBERG · dr. D. CUDEL- dipl. inc. S. SCHUBERT · Frankfurt

GROSSE IiSCHENHEIMER ST. ÖOOO FRANKFURTAM MAIN

TELEPHONE: (0611) 261134 I 287Q14 TELEX: 4131IO

June 12, 1980 Gu / Dö

BAXTER TRAVENOL LABORATORIES, INC. One Baxter Parkway

Deerfield, Illinois 60015, U.S.A.

Dialysis machine for use with an artificial kidney dialysis machine and Method for determining the ultrafiltration rate in such a dialysis machine

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description

The invention relates to a dialysis machine for use with a dialysis machine for generating an artificial kidney a desired ultrafiltration rate and a method for determining the ultrafiltration rate in one such a dialysis machine.

An artificial kidney has a dialysis machine with a dialysis machine, the machine operating the Dialysis machine controls. The dialysis machine is used to treat the patient's blood in such a way that the Water and the waste products are withdrawn from the blood. The dialysis machine has a semi-permeable Membrane that separates the blood and the dialysis fluid from each other, which is passed through the dialysis machine flows. The elimination products are removed by mass transfer through the membrane. The water will withdrawn by ultrafiltration through the membrane.

In some dialysis machines, the dialysis solution is passed through the dialysis machine with negative pressure, i.e. with a Sub-atmospheric pressure subtracted. U.S. Patent 3,878,095 describes such a machine. This machine is also sold by the applicant under the type designation 5M 1352-5M 1355. This machine can also be used as a Disposable machines are called because the dialysis solution is continuously produced and then the machine with flows through the dialysis machine and finally flows out.

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The removal of water from the blood by ultrafiltration is based on the pressure difference that exists at the semi-permeable Membrane is present, i.e. on the pressure difference of the blood flowing through the dialysis machine under positive pressure compared to the dialysis fluid flowing through the dialysis machine at negative pressure. This pressure difference is also referred to as the pressure on the membrane. The amount of water withdrawn from the blood is straightforward associated with this pressure difference.

It is known that it is desirable to reduce the ultrafiltration rate so that the amount and rate, i.e., amount per unit of time, at which water is withdrawn from the patient is controlled. U.S. Patents 3,844,940, 3,979,284 and 3,990,973 describe such ultrafiltration systems .

Apparatus is also known to be used in such negative pressure flow systems is used to create and control the rate of ultrafiltration. In this device, an ultrafiltration branch is provided, which is connected to the flow system next to the inlet of the dialysis solution to the dialysis machine. The ultrafiltration branch includes a variable speed one Pump on that draws fluid from the dialyzer at a rate equivalent to the ultrafiltration rate is also a flow meter that displays the flow rate and a drain for the withdrawn liquid.

In the operation of this system, the operator adjusts the pump and observes the flow meter until the desired flow rate is reached, which corresponds to the desired ultrafiltration rate. Subsequently observed or does the operator determine the

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lying pressure at which the desired ultrafiltration rate is achieved, the system is then with respect to this Membrane pressure controlled. In this system, however, the manual adjustments and the observations the operator cannot ensure the accuracy required in some situations.

The invention is therefore based on the object of an accurately working dialysis machine and a more precise dialysis method to propose with which the ultrafiltration rate can be built up and controlled very precisely.

This task is solved by the characteristic ι Measures of claims 1 and 8, respectively.

Preferred embodiments of the subject matter of the invention emerge from the subclaims.

It is therefore important for the invention that for the production and control of the ultrafiltration rate, the system which can be used in flow machines with negative pressures, an ultrafiltration branch is provided, the has a piston-cylinder pump that is manufactured very precisely. With this pump liquid is removed from the Dialysis machine in very precisely controlled amounts at very precisely controlled rates during ultrafiltration deducted. The pump is operated by any precisely controllable motor. Stepper motors are used for this preferred. Operation by hand is no longer necessary. The system is preferably used with through-flow machines negative pressure, but it can also be used with other types of machines, such as machines

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with positive pressure, with machines in which the liquid is returned, or with from one Reservoir working machines.

The invention is illustrated below using an exemplary embodiment explained in more detail, from which other important features result. It shows:

1 shows a diagram for a dialysis machine including an ultrafiltration branch with a Piston-cylinder pump, which is constructed like a syringe, and with a stepper motor for Production of the ultrafiltration rate;

Fig. 2 is a partially sectioned side view of the pump;

3 shows an enlarged limit switch cooperating with the pump;

Fig. 4 is an end view of the pump showing a gear for actuating the pump.

Fig. 1 shows a dialysis machine 10 which has three main sections, namely a standard flow system, a control system for the membrane and an ultrafiltration branch.

First, the flow system will be described. This closes a dialysis machine 12 with a semi-permeable membrane that separates the blood flowing through the device from the dialysis solution. Such Dialyeiergeräte can either be of the parallel plate type or of the hollow fiber type. Blood enters the dialyzer through an inlet

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12a and leaves the device via an outlet 12b. The dialysis solution enters the machine through inlet 12c and leaves the device via an outlet 12d. In normal operation, the device is arranged so that the Outlet 12d is above inlet 12c. Through this the removal of gas bubbles formed in the device during dialysis is facilitated.

A supply for the dialysis solution is located upstream of the dialysis machine. The supply is either a storage device for previously prepared dialysis solution or it can freshly prepared and is then mixed by a proportioning device. Fresh dialysis solution flows off the supply 14 via a main line 16, through a device 18 for keeping the flow constant and into a Inlet line 20, which leads to dialysis machine 12. An inlet valve 22 is located upstream of the inlet line of the dialysis machine to allow or provide the power to the dialysis machine. Used dialysis solution leaves the dialysis machine via an outlet line 24 and an outlet valve 26, the dialysis flow from the dialysis machine enabled or terminated. A bypass line is provided which also includes a bypass valve 30, which enables a shunt to the dialysis machine. The bypass line 28 bridges the inlet line 20 and the outlet line 24.

An adjustable control valve 32 for the flow is located downstream of valves 26 and 30 for receiving and controlling the flow. A constant speed pump 34 and negative pressure is located downstream of the control valve 32 to remove the dialysis solution from the supply to pull through the dialysis machine. Alternatively,

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put the control valve 32 and the pump 34 a pump be provided with adjustable conveying speed in order to control the flow of the liquid. The consumed Dialysis solution is discharged via a drain 36.

The detection devices for printing are described below. The pressures inside both the dialysis machines on the side of the blood as well as the dialysis solution are continuously monitored. A pressure transducer 38 for arterial pressure monitors the pressure of the incoming blood and a pressure transducer 40 monitors venous pressure the blood pressure of the returning blood. Two negative pressure transducers are provided to control the pressure of the dialysis solution to measure in the dialysis machine. A negative pressure transducer 42 is provided upstream of the pressure the dialysis fluid at the inlet of the dialysis machine and downstream of the inlet valve 22. Downstream a pressure transducer for negative pressure 44 is provided which controls the pressure at the outlet of the dialysis machine and upstream of the exhaust valve 26 measures.

The transducers 42 and 44 are arranged as close as possible to the dialyzer, whereby the pressure measurement is very accurate. The transducers 42 and 44 are located next to the inlet and outlet of the dialyzer and operate both during the Setting the ultrafiltration operation as well as in Normal operation.

A diaphragm pressure control system includes a diaphragm pressure controller 46 which receives an output from transducers 38, 40, 42 and 44. A desired membrane pressure can be entered into the control unit and the control unit can determine the instantaneous Set the diaphragm pressure to the desired pressure.

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The mean blood pressure within the dialysis machine is determined by the fact that the outputs of the transducer 38 for arterial pressure and the transducer 40 for venous pressure can be averaged. The mean negative pressure in the dialysis machine is determined by the fact that the outputs of transducers 42 and 44 for the negative pressure (upstream and downstream, respectively) be averaged. These averaged pressures are added algebraically, which results in the diaphragm pressure.

The adjustable control valve 32 is also connected to the control device 46 for the diaphragm pressure. A shot of the momentary diaphragm pressure, by which we mean the pressure applied to the diaphragm or its pressure difference 1, is caused by the fact that the control valve 32 so adjusted .t is that a predetermined diaphragm pressure is maintained. This setting takes place in that the control unit has the current membrane pressure, as approximated by the mean blood pressure and the mean negative pressure, with the predetermined membrane pressure, which is determined during the setting of the ultrafiltration, and the is entered into the control unit. Then the valve 32 is opened or closed, so that any differences become as small as possible between the instantaneous and the predetermined pressure. Such control devices are known per se and work either manually or automatically.

The ultrafiltration branch 48 includes a line 50a and a line 50b, and a piston pump 52, a Stepper motor (stepper motor) 54 and a display device 56. The lines 50a and 50b are connected to the piston pump 52 and with the inlet line 20 for the dialysis solution in a position between the inlet valve 22 and the inlet line 12c

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connected for the dialysis machine. The negative pressure transducer 42 is preferably located between them Connection and the inlet of the dialysis machine.

The piston pump 52, the stepping motor 54 and the display device 56 are mounted on a plate 58. This unit is shown in detail in Figures 2-4.

The piston pump 52 is constructed like a single-acting syringe. She has a very precise editing Cylinder 60, one end of which is closed with a cap 62, and a retractable piston assembly 64. This piston assembly includes a piston 66 and a threaded piston rod 68. the The inside of the cylinder is very precisely machined and its cross-sectional area is very uniform. The piston carries a seal for sealing the annular gap. The cylinder, end cap and piston define one Chamber, the volume of which can be determined and changed very precisely. The maximum volume of this chamber is included about 200 ml. This is sufficient capacity for the desired ultrafiltration rate.

The lines 50a and 50b are connected to the end cap so that the liquid flows into the piston pump 52 and can flow through it.

Fig. 3 shows that an arm 70 is attached to one end of the piston rod 68, opposite the piston. As the arm moves, it comes to rest against a limit switch 72 which is attached to the plate. The limit switch terminates the retraction movement of the piston when it reaches a predetermined point, usually at the end of the working stroke of the piston.

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The stepper motor is connected to the piston rod via a gear 74 connected. The gearbox also connects the motor 54 to a potentiometer or indicator 56 which indicates whether the engine works.

The motor 54 is a stepper motor. This means that its anchor moves by a fixed one each time it receives an impulse Angle rotates. In other words, when a pulse arrives at the motor, its armature rotates one step. By precisely controlling the number of pulses delivered to the motor and the rate at which they are delivered, the Operation of the engine very precisely controlled. In turn, because the operation of the engine is precisely controlled, the retraction rate of the piston is precisely controlled. This in turn controls very precisely the change in volume in the pump chamber. The motor used for this is preferably from the Rapidsyn, Dana Industrial, 11901 Burke Street, Santa Fe Springs, California 90670, USA is available under serial number 23 as a DC stepper motor. The model number is 23 H-503. See also US Pat. No. 3,519,859.

In this motor, the armature rotates in steps of 1.8 degrees, so that 200 steps make a full revolution of the anchor. So a motor turns the motor 1.8 degrees. The gear 74 transmits this rotation to a specific one Liquid withdrawal rate. In the system used, 10 pulses / second correspond to an increase in Chamber volume of 1 ml / minute. This in turn corresponds to a flow rate of the liquid or an ultrafiltration rate of one ml / minute (20 pulses / second correspond to 2 ml / minute etc.)

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The pulses are generated and supplied to the motor by an input system 76 with a generator 78 for the pulses. This system with a generator is known per se. The desired flow rate is entered into the system, and the appropriate number of pulses are then generated and fed to motor 54. So becomes the entrance to the system of 2 ml / minute entered, 20 pulses / second are entered given to the motor 54.

The transmission can, if necessary, also be modified so that a different ratio between the motor steps and the withdrawal of the liquid is achieved.

Because the armature of the motor is incremental, it may be desirable to connect a flywheel or other damping device to the motor or to the gear train.

Other drives can also be used instead of the stepper motor provided as long as the rate of retraction of the plunger can be precisely controlled thereby (rate means linear movement per unit of time),

The main advantage of the system described is that the cross-sectional area of the cylinder is known exactly and that the rate of movement of the piston can be precisely controlled. This in turn can reduce the rate of liquid drawn into the pump can be controlled very precisely. So this system has no potential for error regarding the setting and the determination of the ultrafiltration rate.

In normal operation, which is sometimes also referred to as dialysis operation, blood flows through the dialysis system

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device and the pump 34 with negative pressure draws the dialysis solution from the supply 14, through the flow device 18, through the inlet line 20 and through the dialysis machine 12. The dialysis machine uses up Dialysis fluid via line 24, valve 32, the pump 34 and the drain discharged. The negative pressure inside the dialysis machine is controlled by that the control valve 18 is adjusted so that the desired negative pressure is achieved. During normal operation the valves 22 and 26 are open so that the flow is directed to and away from the dialysis machine is. Under certain conditions, however, the valves 22 and 26 are closed, so that the flow through the dialysis machine is ended, the dialysis machine being switched off from the flow system. At the same time will the bypass valve 30 is opened so that the flow from the supply 14 goes directly to the pump 34.

If the ultrafiltration rate is to be determined or adjusted, the dialysis mode is exited. The Maschi \ e is then operated in the setting mode for the ultrafiltration. In this one-part operation, the valves 22 and 26 are closed, so that the dialysis machine is switched off, and the bypass valve 30 is opened. The blood is still flowing through the blood side of the dialyzer. The ultrafiltration branch 48 is activated and the motor 54 is operated at a rate corresponding to the desired ultrafiltration rate.

If the piston is withdrawn, it draws liquid out of the flow system, which in turn Fluid flows through the semi-permeable membrane from the blood side to the dialysis solution side. These

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Flow rate is equivalent to the ultrafiltration rate. Only water flows into the branch, which the membrane from Blood has traversed into the dialysis solution. When the desired ultrafiltration rate is reached, the membrane pressure stabilizes. It will now be the middle one negative pressure indicated by transducers 42 and 44 is noted. This mean pressure becomes algebraic is added to the mean blood pressure displayed by transducers 38 and 40. This value will be automatic determined and entered into the control unit 46. This value represents the membrane pressure, which represents the desired ultrafiltration rate.

If the machine returns to dialyser mode, the valves 22 and 26 are opened, the bypass valve is closed and the motor 54 moves the Piston 66 in the other direction, with all of the withdrawn solution being returned to the system in its entirety, and and no solution ends up in the drain. The pump pulls the dialysis solution through the system.

In this dialysis operation, the control system compares for the diaphragm pressure the entered diaphragm pressure with the current pressure, as determined by the transducers 38, 40, 42 and 44 is measured. Correspondingly, the valve 32 is operated to control the negative pressure in such a way that the current diaphragm pressure remains set at a value which corresponds to the entered diaphragm pressure comes as close as possible.

The machine operator can decide at different times during the dialysis operation whether it is necessary to readjust the ultrafiltration rate, for example because the dialysis machine is under changed

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Conditions is working because the patient's condition has changed, or the like. About the ultrafiltration rate set again, the system is in the described setting mode for the ultrafiltration transferred again, the current to the dialysis machine being switched off by closing the valves 22 and 26. The ultrafiltration branch 48 is then activated with the pump. The procedure described above is now performed at a certain ultrafiltration rate set up and to determine the desired membrane pressure. An automatic operation will be for some Preferred functions that the operator can also perform by hand.

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Claims (8)

Claims 1. j dialysis machine for use with a dialysis machine """of an artificial kidney for generating a desired ultrafiltration rate, the machine having - A flow system for the supply of fresh dialysis solution to the dialysis machine and for the drainage of used dialysis solution from the dialysis machine, - Valves in the flow system for determining the flow to and from the dialysis machine , and - an ultrafiltration branch that connects to the flow system between the valve and the dialysis unit connected is, characterized, that the ultrafiltration branch (48) has a single-acting piston pump (52) with the liquid from the flow system is withdrawn, as well as a motor (54) connected to the pump for driving the pump in such a way that that fluid is withdrawn from the system in precisely controlled amounts and at a precisely controlled rate will. 2. Dialysis machine according to claim 1, characterized, that the motor (54) is a stepping motor. 030065/0664 ORIGINAL INSPECTED 3. Dialysis machine according to claim 1, characterized marked t, that the pump (52) includes the following means: a) a cylinder (60) which forms a chamber with a precisely defined inner surface, b) a piston (66) which can slide sealingly on the inner surface, c) a piston rod (68) connected to the piston (66) iä. To move the piston within the cylinder, wherein d) the motor is in operative connection with the piston rod (68) in order to move it. 4. Dialysis machine according to claim 3, characterized in that that a gear (74) connects the motor (54) with the piston rod (68). 5. Dialysis machine according to claim 1, characterized in that that a potentiometer (56) is connected to the motor (54) to indicate the operation of the motor. 6. Dialysis machine according to claim 2, characterized in that that each step of the motor (54) is a predetermined change in chamber volume based on the movement of the piston (66) corresponds. 030065/0664 7. Dialysis machine according to claim 6, characterized in that that the rate of stepping can be precisely controlled, thereby reducing the rate of withdrawal of the Fluldes can also be precisely controlled. 8. Procedure for determining the ultrafiltration rate in a dialyzer of the negative pressure type with a semipermeable membrane, wherein a dialysis solution through the dialysis machine on one side of the membrane under negative pressure and the blood the other side of the membrane, and wherein inlet and outlet lines are provided which supply or discharge the blood and the dialysis solution from the dialysis machine, characterized, (a) that the blood and the dialysis solution are passed through the dialysis machine (12), (b) that the line of dialysis solution to the dialysis machine and from the dialysis machine is stopped, (c) whereupon fluid is withdrawn from the dialysis machine in fixed amounts at a predetermined rate will, (d) that the pressure at the membrane associated with this flow rate is measured and (e) that the flow of dialysis solution through the dialysis machine is switched on again, 030085/0684 (f) whereupon the current pressure on the membrane during normal operation is controlled so that the predetermined pressure on the diaphragm is approached. The patent attorney Dr _? D. Gudel Ö3006S / 06S4