DD157952A3 - DEVICE FOR EXTRACORPORAL TREATMENT OF BLOOD - Google Patents

Abstract

The invention relates to hemodialysis and hemofiltration therapy and is primarily for the treatment of chronic renal insufficiency. The aim of the invention is the possibility of a free change between the treatment methods hemodialysis, haemofiltration and sequential ultrafiltration and thus in particular an optimal, individual therapy regimen. The object of the invention is a uniform technical system for all mentioned treatment methods, whereby the determination of the treatment effectiveness and the control of the treatment process should be based on a uniform continuous ultrafiltration measurement. The device according to the invention has i.a. two control-coupled pumps with different, constant delivery flows, which are in a fixed ratio. The excess occurring in the system is dissipated to the outside and detected by a flow meter, with the output signal via a central control unit, a pressure-influencing element for controlling the ultrafiltration rate is controlled. By means of the central control unit and separately controllable valves a switch to pure ultrafiltration is possible.

Description

Device for the extracorporeal treatment of blood

Field of application of the invention

The invention relates to a device for hemodialysis and hemofiltration therapy, primarily for the treatment of chronic renal insufficiency.

Characteristic of the known technical solutions

For extracorporeal treatment of the blood of kidney patients, methods are known which are referred to as hemodialysis and hemofiltration or as sequential ultrafiltration, an intermediate form of hemodialysis and hemofiltration. Each of these methods has certain advantages and disadvantages. Their respective use depends on the clinical-therapeutic requirements and on the technical equipment systems available. The principles underlying the individual methods of action so far required the use of different device systems.

A hemodialysis apparatus includes a mixing device that proportions a concentrate with pure water in a fixed ratio. The resulting dialysate is heated by means of a thermostat to a constant temperature.

A vacuum pump sucks the dialysate through a dialyzer, at the membrane surface, a mass transfer takes place. Furthermore, a flow indicator and a device for gas separation from the dialysate to the usual standard, To adjust the Dialysatdruckes a throttle valve is arranged in front of the dialyzer. The dialyzer can be bypassed in case of faulty dialysate by means of a bypass. For the safety of the patient, the dialysate temperature, dialysate pressure, conductivity and "blood leak" are usually displayed and monitored. For some time, the measurement of ultrafiltration belongs to the equipment of a hemodialysis device. Such a hemodialysis device is described in DE-OS 25 039 039. As a special feature, this device has two control-coupled pumps, which are arranged before or after the dialyzer and have equivalent flow rates. The volume difference corresponding to the ultrafiltrate is detected via a hydraulic bridge and displayed by a flow meter or collected directly in a measuring vessel. The disadvantage of this principle for the measurement of the ultrafiltration is the difficulty of keeping constant the flow rates of the pumps, independent of internal and external influences, which inevitably lead to errors in the determination of the ultrafiltration rate. A hemofiltration device, such as according to DE-OS 27 54 810, has a device for generating a negative pressure, which is applied to one side of a filter membrane. On the other side of the membrane, the patient's blood is bypassed in the extracorporeal circuit. By Transmembrandruck a filtrate is squeezed, which in addition to V / asser u. a · contains urinary substances. At the same time a sterile and pyrogen-free replacement liquid must be added to the blood in accordance with the resulting amount of FiI, in order to maintain the volume balance minus a desired weight loss ", The balance is in addition to the vacuum pump with pressure measuring a considerable technical effort and is

Usually realized by weighting principles (eg, DE-OS 28 32 870).

The principle of sequential ultrafiltration is characterized in that, in addition to normal hemodialysis, the dialyzer (with normal dialysis membrane) is pressurized without dialysate with negative pressure »This is the blood withdrawn an ultrafiltrate amount that does not normally have to be substituted · The process is usually in Combination with dialysis performed on the patient. There are no known devices that can realize both a hemodialysis and sequential ultrafiltration as well as hemofiltration according to a uniform principle of action.

Object of the invention

The aim of the invention is a system for extracorporeal treatment of blood, which allows a free change between the treatment methods hemodialysis, hemofiltration and sequential ultrafiltration and thus in particular an optimal, individual therapy regimen, wherein the disadvantages described in the prior art should be avoided without the technical equipment Compared to a pure hemodialysis machine with continuous ultrafiltration measurement to increase significantly.

Essence of the invention

The invention has for its object to realize the previously different device systems requiring hemodialysis and hemofiltration including the transitional form sequential ultrafiltration in a single technical system, da3 offers the possibility of these different methods in any

Order to determine the effectiveness of the treatment and the control of the treatment process for each of the three methods on the basis of a uniform continuous ultrafiltration measurement,

The invention relates to a device for the extracorporeal treatment of blood.

The device consists inter alia of a first pump which conveys dialysate from a dialysate source via a degassing and heating system into a dialyzer, a second pump which is coupled to the first pump in a controlled manner and generates a negative pressure in the dialyzer, a bypass bypassing the dialyzer which allows by means of switchable valves a temporary diversion of the dialysate flow, and a controllable pressure-influencing element in front of the dialyzer. According to the invention, the two pumps have constant flow rates, which are in a fixed relationship to one another, wherein the first pump has a larger flow rate. Between the first pump and the dialyzer, a container is further arranged, which communicates via a line with the atmosphere, to which a flow meter is connected. An output of the flow meter is used via the central control unit for controlling the pressure-influencing element disposed between the container and the dialyzer. The switchable valves can be controlled separately from the central control unit. By arranging an additional pressure-increasing and the delivery volume not influencing the pump before the dialyzer and an adjustable flow resistance after the dialyzer, a further advantageous embodiment of the device according to the invention is possible, the overflowing the line in communication with the associated excess line by means of Durchflußmesoers in a proportional measured value implemented. In the central control is below a difference between this electrical

This difference is displayed as the current ultrafiltration rate and used to control the required transmembrane pressure and / or to control one's infusion system. When changing the setting conditions and / or at fixed intervals, the dialyzer is briefly separated, the dialysate flow passed through the bypass and the case of the flow meter detected value from the central control than the constant increase in the first pump corresponding signal used for subtraction in the following working phase · By switching off the dialyzer on the input side and opening the bypass by means of the switchable valves, the treatment process is switched to pure ultrafiltration · Thus, even in pure ultrafiltration operation, the dialysis system works and generates the required transmembrane pressure, whereby the flow is minimized via the central control. This solution allows the determination of the ultrafiltration rate in both hemodialysis and hemofiltration to remain on the bes This solution thus obviates the known weighing-based complicated balancing systems for hemofiltration and replaces their task with the device that is necessary anyway in modern dialysis machines for the measurement of the ultrafiltration rate · The substitution rate required for the hemofiltration is formed by simple difference formation from the measured ultrafiltration rate and the medically prescribed drainage rate of the patient · This substitution flow can be determined by

a conventional infusion pump, which is generated via the central control unit, controlled by the difference signal, the respective required delivery rate. However, any controllable metering devices can also be used ·

The ultrafiltration measurement is based on the control-coupled pumps, whose flow rates are in an exact dosing ratio. In this case, the first pump which supplies the container arranged in front of the dialyzer delivers an excess, which flows off via the line connected to the atmosphere. This overflow may, for example, be in the range of 5 % of the delivery rate. The effluent over the overflow of the container amount is detected by means of a flow meter of sufficient accuracy, which emits an electrical signal proportional to the flow. For example, turbine flowmeters with achievable measurement errors of less than 0.5 % of the final flow rate are suitable for this task. Various disturbance variables such as fluctuations in the velocity of the pump systems, gas inclusions in the dialysate, pressure dependencies in the system, etc. can lead to a change in the overflow and thus to a falsification of the ultrafiltration rate. As a crucial component of the present invention, these disturbances are eliminated by determining the overflow at constant time intervals and each time the setting parameters are changed. The measured overflow will be via the central control in each case to the new zero point for the determination of the ultrafiltration rate. The determination of the overflow is done simply by closing the dialyzer on both sides and opening the bypass. Here, the ultrafiltration UuIl, so that only the systemic overflow is displayed. Preferably, the bypass is to be connected directly to the dialyzer in parallel, so that no pressure-influencing elements, which lie between the bypass and the dialyzer, can lead to falsifications. Out

For this reason, it is also advantageous to choose for the bypass a pressure drop which corresponds approximately to that of the dialyzer.

The time intervals for determining the overflow must be selected so that no disturbing deviations in the accuracy occur and that the treatment efficiency is not impaired by the measuring time. Measuring distances in the half-hour interval, for example, are well suited to meet both requirements · With this solution is a mechanically easy to implement possibility for ultrafiltration measurement, which makes no extreme demands on the accuracy of the flow measurement and the total dosage compared to the known solutions and continuously an ultrafiltration proportional Signal supplies. This signal is used according to the invention for controlling the negative pressure in the system by a pressure-influencing element bypass and dialyzer is adjusted by a conventional control loop so that the dialyzer results in a Transmembrandruck that ensures a preselectable ultrafiltration rate or · at a fixed treatment time a preselected Gesamtultrafiltration. In addition, according to the invention, a pressure increasing device in front of the dialyzer - preferably a pump that does not affect the JFördervo lumen - and an adjustable flow resistance after the dialyzer can be provided · This dialysate side, a pressure can be generated, which compensates for the blood pressure, so that a transmembrane pressure Hull As a result, ultrafiltration rates of Hull can be achieved, which are particularly advantageous for the dialysis phase in sequential ultrafiltration or even for special cases ultrafiltration in the direction of blood. By the ultrafiltration measurement according to the invention it is ensured that these too "negative" ultrafiltration can be accurately measured unless it exceeds the constant pumping of the first pump.

The solution according to the invention makes it possible to program the ultrafiltration rate or dewatering rate over time or as a function of certain measured parameters and the change between dialysis and ultrafiltration (or hemofiltration, for example) using a conventional microcomputer system as the central controller if substitution is required) · When switching between the phases of pyrolysis and dialysis, a timely automatic preparation of the dialysate is also possible via the central control so that, on the one hand, there can be a complete transition between treatment phases and, on the other hand, no unnecessary consumption of energy and dialysis concentrate ·

embodiment

The drawing shows the basic structure of an embodiment of the device according to the invention. Shown are only relevant to the invention elements of the system, such as. For example, the monitoring element (eg, temperature measurement, conductivity measurement, pressure measurement) associated with such an unavoidable prior art device and the entire blood circuit are not shown. A first pump 1 sucks pure water from a water tank 2 . Between this pump 1 and the water tank, a heater 3 for heating the water to body temperature and a degassing device 4 are arranged. At the same time, this pump draws in 1 dialysis concentrate from a reservoir 5. The associated intake line can be closed by a solenoid valve 6. In the pump 1, the dialysate of water and concentrate is mixed approximately in the ratio of 34: 1 or in the ratios required for bicarbonate dialysis. The pump 1 conveys the heated and degassed mixture in a container 7, wherein the promotion takes place with Do3ierpumpenqualität. Pure

The pump 1 can be used one of the known Dosierpumpenprinzipe. From the container 7, a second pump 8 delivers the dialysate through the dialyzer 26. After the pump 8, the dialysate is usually discarded. The pump 8 has analogous to the pump 1 Dosierpumpenqualität and is the pump 1 in a precisely constant Pörderverhältnis, This is achieved in the embodiment by a common drive 9 of both pumps 1 and 8, which form a unitary structural design. The pump 1 has compared to the pump 8 by a precisely constant Paktor (advantageously 5 %) higher delivery volume. This excess flows from the container via line 10 into the drain. The conduit 10 is designed so that a ventilation of the container 7 is achieved by them and the liquid in the container 7 is thus always in terms of pressure in equilibrium with the atmosphere. This can be achieved either through an opening in the container 7 with overflow, a vent in the conduit 10, or preferably a design of the cross-sections and the drainage level of the conduit 10 that meets this requirement. In the line 10, a flow meter 11 is connected, which outputs a flow signal proportional to the electrical signal, for example, a turbine flow meter with an accuracy of 1%, with a maximum flow range of 5 l / h. By means of a control valve 12, which is actuated by a magnetic or electromotive drive, the following hydraulic system can imprint a negative pressure, which leads to ultrafiltration of liquid from the blood into the dialysate when the blood circulation is closed. This amount of liquid is added to the flow defined by pumps 1 and 8 so that the same amount of liquid must escape through the single opening of the system, line 10. The difference between the flows via the line 10 when the dialyzer 26 is connected and when the dialysate flow is diverted via a bypass line 18 is thus a direct measure of the ultrafiltration.

The value of the basic flow through the line 10 without dialyzer is automatically subtracted from the actual value signal of the flow meter 11 (Hullpunktverschiebung) via the central control 13, so that the current ultrafiltration rate is displayed directly · To errors in the constant dosage of the pump 8 through become vacant in the dialyzer To avoid gases, a gas separator 14 is arranged in front of the pump 8. This may be designed as a conventional float chamber, In the previous description, the solution requires the highest precision of the identical-proportional metering of the pumps 1 and 8, since an accuracy of the measurement of the ultrafiltration rate of about 50 ml / h at a flow of dialysate of up to 50 l / h must be achieved and any fluctuation of the basic flow would lead to a direct error of the display. These extreme demands on the dosing accuracy are eliminated by the central control 13 at each change of setting parameters and at fixed intervals, advantageously 30 minutes automatically the valves 15 and 16 are closed and the valve 17 in the bypass line 18 is briefly (until the flow stabilizes through the conduit 10) is opened. In the case of the case, only the basic flow flows through the conduit 10 HuIlpunkt according to these measurements each automatically v pushed, so that the accuracy of the ultrafiltration measurement is independent of drift phenomena, tolerances and dependencies of the dosage of variable system parameters and thus a crucial simplification or even feasible realization of the demands on the pumps 1 and 8 is possible. The bypass line 18 is arranged so that it is directly parallel to the dialyzer 26 and has approximately the same flow resistance, to avoid errors due to different pressure drops · The central controller 13 includes conventional control systems, which when entering a target value of the ultrafiltration rate or when entering a Total ultrafiltration quantity and a

given dialysis time or when entering a desired time course of the ultrafiltration rate by the operator according to the optimal therapy, the control valve 12 and thus the transmembrane pressure on the dialyzer 26 influence so that the desired ultrafiltration rate is reached. The control loop is closed by the actual value signal of the flow meter 11. For rapid achievement of the target value of the ultrafiltration rate, the average ultrafiltration rate of the dialyzer type is additionally input according to the manufacturer's instructions to the central controller 13t, which determines the corresponding transmembrane pressure and sets it as the initial value via the control valve 12. Significant deviations between the transmembrane pressure practically necessary for a particular ultrafiltration rate and the expected for a particular dialyzer in accordance with the manufacturer's indication Transmerabrandruck indicate disturbances of the system or defective dialyzer and are issued by the central controller 13 as an alarm. The central controller 13 is advantageously constructed in microprocessor-controlled software-oriented logic, wherein all measurement functions are digitized prior to processing.

The embodiment further comprises an additional pump 19 and a second control valve 20, which serve to generate a positive pressure on the membrane of the dialyzer 26, whereby a transmembrane pressure of Hull or »even a negative transmembrane pressure can be achieved. This pump 19 serves only to increase the pressure and must not have any metering properties. Preferably, a centrifugal pump is suitable for this purpose. If an ultrafiltration rate is required which is lower than achievable with the control valve 12 fully open, the central control 13 automatically switches over to the pressure boosting system described. The previously described part of the exemplary embodiment represents a hemodialysis machine with advantageous ultrafiltration measurement and balancing of the valve 16

and opening the valve 17, this device operates as a pure Pilittsssystetn, since applied to the membrane of the dialyzer 26 via the open line 21 of the negative pressure generated in the system and thereby an ultrafiltrate amount corresponding to the resulting transmembrane pressure via line 21 flows. The remaining punctures of the device remain unaffected so that the ultrafiltration measurement is again effected via the flow meter 11, whereby only the valve 15 is closed to determine the basic flow. In order to save dialysis concentrate and energy, the heating 3 and the valve 6 are automatically activated in the pilot operation The concentrate supply is switched off. Furthermore, the flow through the bypass line 18 is minimized via the drive 9 of the pumps 1 and 8.

For the transition from ultrafiltration to dialysis, the heater 3 and the concentrate supply are automatically switched on by the central controller 13 about 10 minutes before the programmed start of dialysis, so that a stable mixture is present at the beginning of the dialysis. The embodiment is supplemented by a substitution system for hemofiltration, which involves ultrafiltration of the order of 20 liters per treatment, which is balanced by simultaneous substitution of fluid into the bloodstream. The substitution rate is calculated from the difference between the measured ultrafiltration rate and the medically required drainage rate by the central controller 13. With this value, a conventional infusion pump 22 is controlled by the central controller 13, which conveys the required amount of liquid from a reservoir 23 into the bloodstream. Depending on the indication, the addition may take place before the dialyzer 26 (predilution) or after the dialyzer 26 (postdilutation). For this purpose, valves 24 and 25 are provided which allow a choice of method or a programmed timed change. Since hemofiltration can result in ultrafiltration rates of up to 10 l / h »is an extension of the measuring range

the flow meter 11 is required, which takes place automatically via the central controller 13. The device described allows a freely programmable change between dialysis, ultrafiltration and ultrafiltration with substitution (hemofiltration) or, dialysis with ultrafiltration and substitution (hemofiltration) to achieve an optimal, individual therapy regime ·

Claims (2)

invention claim 1 · Device for extracorporeal treatment of blood, consisting of a first pump, which promotes dialysate from a dialysate via a degassing and heating system in a dialyzer, a control pump coupled to the first pump second pump, which generates a negative pressure in the dialyzer, the one ? dialyzer immediate bypass which allows a temporary diversion of the dialysate by means of switchable valves, and a controllable pressure-influencing element in front of the dialyzer dadurjch JGE £ ennzeichnet _a that the two pumps (1; 8) have constant flow rates which are in a fixed ratio to one another wherein the first pump (1) has a larger delivery rate, between the first pump (1) and the bialyzer (26) a container (7) is arranged, which communicates with the atmosphere via a conduit (10) a flow meter (11) is connected, that the controllable pressure-influencing element (12) between in the container (10) and the dialyzer (26) is arranged, wherein an output signal of the Durchflußmessero (11) via a central control unit (13) for controlling the pressure-influencing element (12) is used, and in that the switchable valves (15; 16; 17) can be controlled separately from the central control unit (13) 2 · Device according to item 1, characterized Porsche Style nzeichnet that before the dialyzer (26) in addition a pressure-increasing and the delivery volume not influencing pump (19) and after the dialyzer (26) an adjustable flow resistance (20) are arranged See 1See drawings