Identifying the position and correct mounting of a syringe plunger of a syringe in a syringe pump

Abstract

The present invention relates to a device and a method for simultaneously identifying the correct mounting of a syringe plunger (301) of a syringe (300) in a retaining device (303) of a syringe pump (201) and the position of the retaining device (303) of the syringe pump (201). The invention further comprises a medical treatment system comprising the device according to the invention and a module having a control device comprising the device according to the invention.

Description

[0001] Detection of the position and proper clamping of a syringe plunger in a syringe pump

[0002] Technical area

[0003] The present invention relates to a device for detecting the proper clamping of a syringe plunger in a holding device of a syringe pump and the position of the holding device of the syringe pump. Furthermore, the invention encompasses a medical treatment system and a method for detecting the position and proper clamping of a syringe plunger in a holding device of a syringe pump.

[0004] background

[0005] Syringe pumps for injecting medical fluids are used in medical settings. They are usually used to clamp a syringe filled with a medical fluid, which is at least indirectly connected to a patient's vascular system via a fluid line. The aim here is to administer the medical fluid to the patient in a predetermined dose and over a predefined period of time. The type of fluid to be administered can vary greatly. Typically, however, it is medication such as anesthetics or medication for the treatment of various illnesses or medications that are necessary for medical treatment, e.g., as part of hemodialysis treatment. Medications administered as part of hemodialysis treatment include, for example, heparin or calcium complexing agents in the context of citrate anticoagulation.

[0006] Hemodialysis is a form of renal replacement therapy for acute or chronic kidney failure. Hemodialysis is an extracorporeal procedure in which the blood to be purified is removed from the patient and passed extracorporeally through a dialysis filter, usually in countercurrent, through a semipermeable membrane, past a special dialysis fluid, the dialysate.

[0007] The substance concentration of the dialysate corresponds to the concentration in the blood of a healthy person. Due to the different substance concentrations of blood and dialysate, the substances that are excreted in the urine diffuse through the membrane from the blood side of the membrane to the dialysate side, while simultaneously, electrolytes present in the blood and dialysate diffuse across the membrane of the dialysis filter from the side of higher concentration to the side of lower concentration. By applying transmembrane pressure, metabolism can be further influenced and excess water can be removed from the blood.

[0008] In order to prevent unwanted coagulation of the blood, e.g. in the dialysis filter, during the extracorporeal procedure, the administration of an anticoagulant is medically indicated. Heparin in fluid form is usually used for this purpose. The heparin is usually contained in a syringe that is clamped into a syringe pump, from which it is injected into the blood-carrying fluid line of the extracorporeal blood circuit. Proper clamping of the syringe into the syringe pump, as well as correct dosing of the heparin, is important. A missing, delayed, or insufficient dose of heparin can lead to clotting of the patient's blood, e.g. in the dialysis filter, which can clog the dialysis filter and thus reduce the effectiveness of the hemodialysis treatment or lead to unwanted increases in pressure in the extracorporeal blood circuit. Medical complications from blood clots are also possible.Monitoring and close control of the functioning of the syringe pump is therefore desirable.

[0009] Devices for detecting the position of the syringe plunger are known from the state of the art.

[0010] In the prior art, position detection is often achieved using an electrical resistance track connected to the holding device for the syringe plunger via electrical sliding contacts. Depending on the position of the electrical sliding contact on the resistance track, a voltage dependent on the position of the electrical sliding contact can be tapped, enabling position detection of the syringe plunger and thus an estimation of the current or already administered amount of fluid. Since an improperly clamped syringe, e.g., if the syringe plunger is not directly connected to the holding device via a frictional connection, can generate erroneous data regarding the administered dose, additional detection of proper syringe clamping is desirable.

[0011] The prior art provides solutions to the problem of detecting the proper clamping of a syringe plunger into the syringe pump and determining the current position of the syringe plunger in a holding device. These solutions typically involve two separate voltage sources and circuits, each of which can independently monitor the proper clamping and position of the syringe plunger. However, the prior art presents the problem of a technically simplified detection of the proper clamping and position of a syringe plunger, so that only a single voltage source or a single, connected circuit is required.

[0012] Summary of the invention

[0013] The object is achieved by a device according to claim 1, a medical treatment system according to claim 6, a method according to claim 13 and a module according to claim 15.

[0014] Accordingly, a device is provided for detecting the proper clamping of a syringe plunger in a holding device of a syringe pump and the position of the holding device of the syringe pump. The device comprises a resistance track and an electrical sliding contact, wherein the sliding contact is configured to slide on the resistance track, so that the variable resistors R51 are formed between the first end of the resistance track and the sliding contact, and R52 between the second end of the resistance track and the sliding contact. Furthermore, the device is configured such that a change in the position of the syringe plunger of the syringe inserted into the syringe pump causes a change in the position of the sliding contact on the resistance track. The device according to the invention further comprises a switching element.The device and the switching element interact in such a way that the electrical conductivity of the switching element changes depending on whether the syringe plunger of the syringe is properly clamped into the holding device of the syringe pump. Furthermore, the switching element and the device interact in such a way that, when a voltage U5 is applied to the resistance track, the current IR5 flowing through the resistance track depends on the electrical conductivity of the switching element. The sliding contact and the switching element are to be understood as different devices; in particular, the sliding contact is in constant contact with the resistance track. Furthermore, a medical treatment system is proposed which comprises a device according to the invention for detecting the proper clamping of a syringe plunger of a syringe in a holding device of a syringe pump and the position of the holding device of the syringe pump.

[0015] Furthermore, a method for detecting the proper clamping of a syringe plunger of a syringe in a holding device of a syringe pump and the position of the holding device of the syringe pump is proposed. The method comprises measuring a voltage and / or a current on a device, wherein the device comprises a resistance track and an electrical sliding contact. The electrical sliding contact is configured to slide on the resistance track, so that the variable resistors R51 are formed between the first end of the resistance track and the sliding contact, and R52 is formed between the second end of the resistance track and the sliding contact. Furthermore, the device is configured such that a change in the position of the syringe plunger of the syringe inserted into the syringe pump causes a change in the position of the sliding contact on the resistance track. The device further comprises a switching element.The method further comprises closing the position of the holding device and / or the proper clamping of the syringe plunger, wherein the device and the switching element interact such that the electrical conductivity of the switching element changes depending on whether the syringe plunger of the syringe is properly clamped in the holding device of the syringe pump. Furthermore, the switching element and the device interact such that, when a voltage U5 is applied to the resistance track, the current IR5 flowing through the resistance track depends on the electrical conductivity of the switching element. The sliding contact and the switching element are to be understood as different devices; in particular, the sliding contact is in constant contact with the resistance track.Furthermore, a module with a control device is proposed that includes the device according to the invention for detecting the correct clamping of a syringe plunger of a syringe in a holding device of a syringe pump and the position of the holding device of the syringe pump.

[0016] Subclaims 2-5 comprise advantageous embodiments of the proposed device. Subclaims 7-12 comprise advantageous embodiments of the proposed medical treatment system. Subclaim 14 comprises an advantageous embodiment of the proposed method.

[0017] Brief description of the drawings

[0018] The

[0019] Fig. 1 shows a circuit diagram known from the prior art of a device for detecting the correct clamping of a syringe plunger in a holding device of a syringe pump as well as the current position of the holding device of the syringe pump, and the

[0020] Fig. 2 is a schematic representation of a treatment system according to the invention comprising the device according to the invention, and

[0021] Fig. 3 is a schematic representation of a syringe pump comprising the device according to the invention, and

[0022] Fig. 4 is a circuit diagram of a first embodiment of the device according to the invention, and

[0023] Fig. 5 is a circuit diagram of a second embodiment of the device according to the invention.

[0024] Detailed description of an embodiment

[0025] Figure 1 shows a prior art device 100 for detecting the proper clamping of a syringe plunger into the syringe pump as well as the current position of the syringe pump's holding device. Device 100 has two separate circuits 100a and 100b, which are supplied by two separate voltage sources U1 and U2.

[0026] Circuit 100a comprises a resistance track 101, on which an electrical sliding contact 102 is movably arranged such that it can be displaced via translation along the resistance track 101 (here indicated by a double arrow). An electrical voltage U1 is applied between the ends of the resistance track 101. The electrical sliding contact 102 divides the resistance track 101 into a first electrical resistor R1 and a second electrical resistor R2, across which the electrical voltage UR1 drops across R1 and UR2 drops across R2. Depending on the position of the electrical sliding contact 102, the size of the electrical resistors R1 and R2 varies, whereby R1 + R2 = Rtotal applies. Rges is the electrical resistance of the resistance track 101. For example, if the electrical sliding contact 102 in the circuit 100a is located at the left edge of the resistance track 101, then R1 = 0 and R2 = Rges.However, if the electrical sliding contact 102 is positioned at the right edge of the resistance track 101, R1 = Rges and R2 = 0 results. The combination of resistance track 101 and sliding contact 102 thus serves as a voltage divider.

[0027] The sliding contact 102 is mechanically connected to a holding device of a syringe pump, wherein a syringe plunger of a syringe can be clamped into the holding device. The mechanical connection can, for example, comprise a rigid connection or a connection with transmission means (joints, gears). The mechanical connection is configured such that a translational movement of the holding device, e.g., upon actuation of a syringe plunger, is translated into a translational movement of the sliding contact 102 on the resistance track 101. The resulting change in position of the sliding contact 102 results in a relative change in the electrical resistances R1 and R2 and in the voltages UR1 and UR2 dropped across the electrical resistances.Using the voltmeter V1, for example, the electrical voltage UR2 can be measured to determine the position change of the syringe pump's holding device. The position change of the syringe pump's holding device can be determined by comparing it with previously stored data, for example, whereby the stored data assigns a voltage value for UR1 and / or UR2 to a respective position of the syringe plunger.

[0028] Furthermore, the device 100 from the prior art comprises a separate circuit 100b, wherein the circuit 100b is supplied with a voltage source U2. The circuit 100b comprises a switching device 103, wherein the switching device 103 is closed when a syringe plunger is properly clamped, i.e., frictionally connected, to the holding device of the syringe pump. If the switching device is closed, the ammeter AI measures a current strength beyond a limit value, or the ammeter AI measures a current strength below the limit value if the switching device 103 is open, i.e., the syringe plunger has not been clamped properly. The prior art has the disadvantage that two voltage sources and separate circuits are required to determine the position of the holding device and the proper clamping of a syringe plunger in the holding device.

[0029] Figure 2 shows a medical treatment system 200 according to the invention comprising a syringe pump 201, wherein the medical treatment system is designed with a device according to the invention for simultaneously detecting the correct clamping of a syringe plunger of a syringe in the holding device of the syringe pump 201 as well as the position of the holding device of the syringe pump. The medical treatment system 200 can be a system for carrying out renal replacement treatment, e.g., extracorporeal renal replacement treatments such as hemodialysis, hemofiltration, hemodiafiltration, or apheresis. However, the device according to the invention can, in principle, be used in all systems suitable for administering a liquid, e.g., infusion pumps, or within a stand-alone syringe pump, e.g., as a built-in module for installation in another device.

[0030] Figure 2 shows a medical treatment system 200, which is embodied, by way of example, as a hemodialysis system. The medical treatment system 200 has a dialysis filter 202, hose sets 203a-d as well as display means 204 and further input means. The hose sets 203a-d comprise an extracorporeal blood circuit 203a / b and a dialysate circuit 203c / d. The medical treatment system 200 further has a syringe pump 201, which is connected to the extracorporeal blood circuit 203a / b via a hose connection. In the example shown, a syringe is clamped in the syringe pump, wherein the syringe can contain a suitable anticoagulant, e.g. heparin, citrate or ethylenediaminetetraacetate (EDTA) for anticoagulating the blood. The syringe pump comprises an actuator, which drives the syringe plunger of the syringe and thus injects a predefined volume orA predefined rate of anticoagulant is injected into the extracorporeal bloodstream 103a / b. By mixing the blood with the anticoagulant, blood clotting is reduced, thus preventing, for example, unwanted coagulation of the blood.

[0031] The medical treatment system 200 comprises a display device 204, e.g. a screen or a touchscreen as a combined display and

[0032] Input device. Other input devices besides the touchscreen can include a keyboard, a mouse, or a voice interface with a microphone for inputting commands to the medical treatment system 200 using a natural voice. For example, a voice interface can be used to control the medical treatment system 200 without contact, or to record and process user questions, such as those regarding the correct handling of the syringe pump 201 or the medical treatment system 200.

[0033] Patient and / or treatment parameters can be entered via the input device. The treatment progress and health status of a treated patient can be monitored via the display device 204. For example, patient information, the treatment progress, or a currently set medication dose can be shown on the display device 204. An adjustment of a medication dose via the input device may be necessary, for example, if it is determined that a currently configured medication dose is too high or too low. In one embodiment, the display device 204 can output a message, a warning, and / or an alarm depending on a status signal, wherein the status signal is indicative of proper clamping of a syringe in the holding device of the syringe pump 201. The status signal can, for example, be generated by a control device, e.g.a processor device or a microcontroller, depending on the proper or improper clamping of a syringe in the holding device of the syringe pump, wherein the control device can be comprised by the medical treatment system 200.

[0034] For example, if it is detected that the syringe has been properly clamped into the syringe pump 201, this can be displayed on the display device 204. For example, a corresponding message or graphic element can be displayed on the display device if a status signal associated with the proper clamping of the syringe into the syringe pump is received. If the syringe is not properly clamped into the syringe pump or is transferred into an improper state during treatment, e.g., due to vibrations, a message, a warning, and / or an alarm can be output on the screen 204.

[0035] In case of an improper condition of the syringe in the holding device of the syringe pump 201, treatment with the medical

[0036] Treatment system 200 can be stopped and / or blocked. An improper condition exists, for example, if the syringe plunger is not in frictional connection with the holding device for the same. In this case, an ongoing treatment can be stopped or an upcoming treatment blocked until the error, i.e. the improper condition of the syringe in the holding device of the syringe pump 201, has been remedied. A message, a warning, and / or an alarm indicating the error condition can be output via the display device 204 and / or include recommended actions for the user to convert the error condition into a proper condition. This ensures that a patient is only treated when the syringe is properly inserted in the syringe pump 201 and thus, in the case of hemodialysis treatment, that a predetermined medication dose, e.g.Heparin is injected as an anticoagulant into the extracorporeal bloodstream. In a further embodiment, the medical treatment system can have an acoustic output device 206. For example, the acoustic output device 206 can output messages, warnings, and / or alarms if the syringe was clamped into the holding device of the syringe pump correctly or incorrectly. Recommended actions for correcting incorrectly inserted syringes into the holding device of the syringe pump 201 can also be output via the acoustic output device 206. An additional acoustic output device is advantageous here because, in a stressful medical environment, visual messages on a display device can easily be overlooked by medical personnel, and as a result of acoustic warnings or alarms, medical personnel can respond more efficiently to error conditions.

[0037] The medical treatment system 200 may further comprise communication means 205. Communication means may use any technologies known in the art for exchanging data. Data transfers between the medical treatment system 200 and another (not shown) device may be wireless or wired via the communication means 205. The communication means 205 may be used, for example, for data exchange between the medical treatment system 200 and another data processing device (e.g., a server, a computer, and / or another medical device). Exchanged data may include data relating to an ongoing medical treatment, a patient or their medical condition, and / or the medical treatment system 200.For example, data regarding the proper clamping of a syringe into the holding device of the syringe pump 201 can be exchanged with another data processing device via the communication means 205. Advantageous here is the possibility of monitoring the medical treatment system 200 and its components from a remote location and, if necessary, taking measures to ensure or restore the functionality of the medical treatment system 200 and the patient's safety.

[0038] Furthermore, the medical treatment system 200 may have a plurality of electrical connections and / or fluid connections to operate, for example, secondary electrical devices, e.g., a modem or a router.

[0039] Figure 3 shows an advantageous embodiment of the syringe pump 201 with a clamped syringe 300. The syringe 300 comprises a syringe plunger 301 and a tubing 302 for conveying a medical fluid. In the case of hemodialysis treatment, for example, heparin is supplied to an extracorporeal blood circuit as an anticoagulant via the tubing 302. The syringe plunger is clamped into a holding device 303 of the syringe pump 201. The holding device 303 engages and fixes the syringe plunger 301 without play, so that any change in position of the holding device 303 results in a change in position of the syringe plunger 301. The holding device 303 is connected to an actuator unit via a connecting element 304, wherein the actuator unit is responsible for the translational movement of the holding device 303 or the syringe plunger 301.Examples of preferred actuator units are electric motors such as stepper motors, in which the rotational movement of the motor is converted into a translational movement of the spindle attachment, for example via a spindle having a thread and a corresponding spindle attachment that engages in the thread.

[0040] The syringe pump 201 or the holding device 303 for the syringe plunger 301 further comprises a mechanical switch 305. Upon proper clamping of the syringe plunger 301 of the syringe 300 into the holding device 303, i.e., without play and in frictional connection with the holding device 303, the switch 305 is physically activated and brought into a first state, wherein the first state is associated with proper clamping of the syringe plunger 301 of the syringe 300 into the holding device 303. The electrical switching element 406 with the device 400 according to the invention in Figure 4 interact with one another in such a way that the electrical conductivity of the switching element 406 changes depending on whether the clamping of the syringe plunger 301 of the syringe 300 into the holding device 303 of the syringe pump 201 is proper or not, wherein the switching element 406 and the

[0041] Device 400 further interacts such that, when a voltage U4 is applied to the resistance track, the current IR4 flowing through the resistance track depends on the electrical conductivity of the switching element 406. The switch 305 can be mechanically or electrically connected to the electrical switching element 406, so that a first state of the switch 305 corresponds, for example, to an increased conductivity of the switching element 406. For example, the increased conductivity of the switching element 406 can be achieved by a transistor or a mechanical switching device. Likewise, the switch 305 and the switching element 406 from Figure 4 can be identical to one another or operatively connected to one another via a mechanical connection, e.g., a rod, a joint, or similar means.

[0042] Consequently, when a syringe plunger 301 is properly clamped into the holding device 303, the switch 305 is in a first state, in which case the switching element 406 of Fig. 4 may have increased conductivity. If the syringe plunger 301 of the syringe 300 is not properly clamped into the holding device 303, the switch 305 is in a second state. In the second state of the switch 305, the switching element 406 may have a lower conductivity compared to the first state of the switch 305.

[0043] Furthermore, it is possible for a plurality of further intermediate states to exist between the first state and the second state of switch 305, so that the conductivity of switching element 406 continuously fluctuates between a maximum value and a minimum value for the conductivity depending on the intermediate state of switch 305. For example, it can be determined in this way whether and with what force the frictional connection of the holding device 303 to the syringe plunger 301 is ensured. Figure 4 shows a circuit diagram of a first embodiment of the device 400 according to the invention for detecting the position of a syringe plunger 301 of a syringe 300 in a holding device 303 of a syringe pump 201 and the proper clamping of a syringe plunger 301 of a syringe 300 in a holding device 303 of a syringe pump 201.The resistance track 401 comprises an electrical sliding contact 402, which is arranged to be movable so that it can be moved along the resistance track 401 via translation (illustrated here by a double arrow). An electrical voltage U4 is applied between the ends of the resistance track 401. The electrical sliding contact 402 divides the resistance track 401 into a first electrical resistor R41 and a second electrical resistor R42. Depending on the position of the electrical sliding contact 402, the size of the electrical resistors R41 and R42 is varied, whereby R41 + R42 = R4total, where R4total is the resistance of the resistance track 401. For example, if the electrical sliding contact 402 in the device 400 is located at the left edge of the resistance track 401, R41 = 0 and R42 = R4total.However, when the electrical sliding contact 402 is positioned at the right edge of the resistance track 401 of the device 400, R41 = R4ges and R42 = 0 results. The combination of resistance track 401 and sliding contact 402 serves as a voltage divider.

[0044] The electrical sliding contact 402 is connected to the holding device for the syringe plunger 303 of Figure 3 in such a way that a change in the position of the holding device 303 causes a simultaneous and equivalent change in the position of the electrical sliding contact 402 in Figure 4. This can be realized, for example, via a direct mechanical connection of the sliding contact 402 to the holding device 303, or via corresponding mechanical transmissions.

[0045] The electrical sliding contact 402 is further connected via an electrical conductor to an electrical component 405 in Figure 4 and to the switching element 406, wherein the electrical component 405, e.g., an ohmic resistor, and the switching element 406 are connected in parallel. The parallel circuit comprising the electrical component 405 and the switching element 406 is further connected in parallel to R42 of the resistance track 401. The switching element 406 is connected to the switch 305 from Figure 3 in such a way that the switch 305, in a first state, causes the conductivity of the switching element 406 to be greater than the conductivity of the switching element 406 when the switch 305 is in a second state.The first state may be associated with a proper clamping of the syringe plunger 301 in the holding device 303, wherein the second state may be associated with an improper clamping of the syringe plunger 301 in the holding device 303.

[0046] Furthermore, the switching element 406 and the device 400 interact such that the electrical conductivity of the switching element 406 changes depending on whether the clamping of the syringe plunger 301 of the syringe 300 in the holding device 303 of the syringe pump 201 is correct or not, and furthermore, the switching element 406 and the device 400 interact such that when a voltage U4 is applied to the resistance track, the current IR4 flowing through the resistance track depends on the electrical conductivity of the switching element 406.

[0047] In the case of proper clamping of the syringe plunger 301 in the holding device 303, i.e. the conductivity of the switching element 406 is greater compared to improper clamping, for example the total current IR4 is distributed over the resistance track 401 in such a way that the current strength tapped via the amperage meter A43 is smaller than in the case of improper clamping of the syringe plunger 301 in the holding device 303. Analogously the tapped current strengths A41 and A42 are relatively greater in the case of proper clamping of the syringe plunger 301 in the holding device 303 than in the case of improper clamping of the syringe plunger 301 in the holding device 303, since the conductivity of the switching element 406 is greater in the case of proper clamping.

[0048] If the syringe plunger 301 is not properly clamped into the holding device 303, the conductivity of the switching element 406 is relatively lower. In this case, a larger proportion of the electrical current flows through R42, so that the tapped currents A42 and A41 become comparatively smaller.

[0049] The problem of simultaneously detecting the proper clamping of the syringe plunger and the position of the holding device can be solved with the device 400 by first determining and storing several pairs of values ​​for specific configurations of the parameters and variables of the device 400 or the syringe pump 201, on the one hand, and measured values ​​at specific measuring points on the device 400, on the other. At the measuring points, in particular, the current intensity and / or the electrical voltage for an applied voltage U4 for a given configuration of the device 400 can be determined and stored.

[0050] Parameters may include, for example, the ohmic resistance of the electrical component 405, the resistance track 401 and / or the conductivity change of the switching element 406 depending on whether the syringe plunger is properly clamped or not properly clamped in the holding device.

[0051] Furthermore, different configurations of the device 400 can be set by varying variables while keeping parameters constant. For example, different positions of the sliding contact 402 on the resistance track 401 and the associated position of the holding device 303 and / or different conductivity values ​​for the switching element 406 can be set.

[0052] For the various configurations of the parameters and variables of device 400, value pairs from the set configuration and measured values ​​for each different configuration can then be generated and stored by measuring the current and / or the electrical voltage at an applied voltage U4 at one or more measuring points of device 400. For example, in device 400, at one or more of the current measuring points A41, A42, and / or A43, the following cases can be considered: - syringe plunger properly clamped in the holding device, positions of sliding contact 402 or holding device 303 are varied,

[0053] - Syringe plunger not properly clamped in holding device, positions of the sliding contact 402 or the holding device 303 are varied, respectively adjusted and determined and stored for specific ohmic resistances of the electrical component 405 and the resistance track 401 when voltage U4 is applied.

[0054] During operation of the device 400, the stored value pairs from the configuration of the device 400 and the correspondingly stored measured values ​​for electrical voltage and / or current at a measuring point can be used to determine the current operating measured values ​​for current and / or electrical voltage. During operation, the previously determined value pairs from the configuration and the associated measured values ​​can either be directly retrieved and compared, and / or functions derived therefrom (e.g., regression functions based on the pairs from the configuration of the device 400 and the measured values ​​for current and electrical voltage) can be used.

[0055] Figure 4 shows a possible embodiment of the device according to the invention, wherein at at least one of the measuring points for the current intensity A41, A42 and / or A43 the measurement of the current intensity is indicative of whether the syringe plunger 301 is properly clamped in the holding device 303 or not.

[0056] By a suitable selection of the electrical resistances R41, R42 and the electrical resistance of the electrical component 405, the intervals of the measured current intensities at the measuring points A41, A42 and A43 can be clearly separated from one another for the cases of proper clamping or improper clamping of the syringe plunger 301 in the syringe holding device 303 in the syringe pump. In the case that the electrical switching element 406 has a very high conductivity, i.e., the electrical resistance of the switching element 406 approaches zero, approximately the entire current flows through the electrical switching element 406, so that the electrical component 405 is short-circuited and the electrical voltage dropped across the electrical component 405 is approximately zero or negligible. The measured current intensities at A41 and A42 are identical in this configuration and depend only on the variable ohmic resistance R41, i.e.,from the position of the sliding contact 402 on the resistance track 401 or the position of the holding device 303.

[0057] In the case where the electrical switching element 406 has a very low conductivity, i.e., the conductivity approaches zero, the current IR4 is distributed between R41, the electrical component 405, and R42. Thus, the measured currents A41 and A42 are not identical, since a portion of IR4 flows through the electrical component.

[0058] Due to the described behavior of the device 400, it allows simultaneous detection of a proper clamping of the syringe plunger 310 in the holding device 303 as well as the position of the holding device 303 by means of a single connected circuit with a single voltage source U4.

[0059] Compared to the prior art shown in Figure 1, the device 400 according to the invention also offers the advantage of a reduction in cable connections and mechanical connecting elements. In the prior art, in addition to the guide tube on which the holding device 303 for the syringe plunger 310 is mounted, there is a further tube section that is used to guide the cables for the switch 305 or the switching element 406 (in the case that the switching element 406 and the switch 305 are identical). In one embodiment, the parallel circuit comprising the electrical component 405 and the switching element 406 can be integrated into the movable holding device 303, so that the parallel circuit comprising the electrical component 405 and the switching element 406 is connected via the electrical sliding contact 402 to the resistance track 401 on the one hand and to a conductor track arranged parallel to the resistance track 401 on the other.The conductor track is characterized by a comparatively very low electrical resistance. One end of the conductor track is also connected to one end of the resistance track 401. As a result, the additional cable routing known from the prior art, as well as the included connecting cable for the switch 305, can be eliminated.

[0060] Figure 5 shows a further embodiment of a device 500 according to the invention, comprising a resistance track 501 to which the voltage U5 is applied and through which the current IR5 flows. The device 500 furthermore also comprises a sliding contact 502, which can be moved on the resistance track 501 such that the sliding contact 502 divides the resistance track 501 into a first electrical resistor R51 and a second electrical resistor R52, so that the resistance track 501 with the sliding contact 502 functions as a voltage divider. Furthermore, the sliding contact 502 is connected to the holding device 303 of the syringe pump 201 in a similar way to the sliding contact 402 of the device 400. The sliding contact 502 is further connected to an electrical component 505 and a switching element 506 via an electrical conductor, wherein the electrical component 505 and the switching element 506 are each connected in parallel to one another.The parallel circuit, comprising the electrical component 505 and the switching element 506, is further connected in series with an auxiliary electrical resistor 507. The electrical component 505, the switching element 506, and the auxiliary electrical resistor 507 are further connected in parallel with the electrical resistor R52.

[0061] By measuring the electrical voltage V5, the device 500 can also simultaneously detect the correct clamping of the syringe plunger 301 in the holding device 303 and the position of the holding device 303. If the holding device is correctly clamped, i.e. the switching element 506 is in a state of high conductivity, the current flows almost exclusively via R51, the switching element 506 and the auxiliary resistors 507 and R52. In this configuration, the electrical voltage measured at V5 across the parallel connection of 507 and R52 moves within a first voltage interval, wherein the measured voltage within the first voltage interval depends on the position of the holding device 303 or the position of the sliding contact 502 on the resistance track 501.

[0062] In the event of improper clamping of the syringe plunger in the holding device 303, i.e., the switching element 506 is in a state of low conductivity, the electrical current flows via R51, the electrical component 505, the auxiliary resistor 507, and R52. With a suitable selection of the electrical resistance of the electrical component 505, e.g., using a high electrical resistance of the electrical component 505 compared to the other electrical resistors of the device 500, the measured voltage lies within a second voltage interval, wherein the measured voltage within the second voltage interval depends on the position of the holding device 303 or the position of the sliding contact 502 on the resistance track 501.

[0063] The first and second voltage intervals can overlap only slightly if the electrical resistance of the component 505 is selected appropriately, so that during operation both voltage intervals can be differentiated based on the stored value pairs for the different configurations of the device 500 and the stored (pre-stored) measured values ​​for the electrical voltage at the measuring point V5.

[0064] Depending on whether the measurement of the voltage drop (e.g., across V5 in device 500) and / or the measured electrical current (e.g., at A41, A42, and / or A43 in device 400) is above or below a limit value, a status signal can be generated by the control device of the medical treatment device 200 and output via the display device 204. The control device can be embodied as part of the medical treatment system 200 of Fig. 2 or, starting from the medical treatment system 200, can be located at a remote location, e.g., in a data center.

[0065] Taking the status signal into account, the medical treatment system 200 can issue a notice, a warning, and / or an alarm via the display device and / or the acoustic output device. This offers the advantage that medical personnel are informed in a timely manner, for example, about proper or improper clamping of the syringe plunger in the holding device 203 of the syringe pump 101. Furthermore, depending on the status signal, a treatment can be enabled, blocked, and / or stopped, so that the safety of the patient is always guaranteed, e.g. in the event of improper clamping of the syringe 200. In addition, depending on the status signal, a visual and / or acoustic operating recommendation can be issued. For example, in the event of improper clamping of the syringe plunger 301 in the holding device 303 from Fig.3 a graphic and / or a video is displayed so that the medical personnel can clamp the syringe 300 correctly or correct an incorrect clamping.

Claims

Patent claims 1. Device 500 for detecting the correct clamping of a syringe plunger 301 of a syringe 300 in a holding device 303 of a syringe pump 201 and the position of the holding device 303 of the syringe pump 201, comprising: a. a resistance track 501, b. an electrical sliding contact 502, configured to slide on the resistance track 501, so that the variable resistors R51 are formed between the first end of the resistance track 501 and the sliding contact 502 and R52 between the second end of the resistance track 501 and the sliding contact 502, i. wherein the device 500 is configured such that a change in the position of the syringe plunger 301 of the syringe 300 inserted into the syringe pump 201 causes a change in the position of the sliding contact 502 on the resistance track 501, c. a switching element 506, i.wherein the device 500 and the switching element 506 interact such that the electrical conductivity of the switching element 506 changes depending on whether the clamping of the syringe plunger 301 of the syringe 300 in the holding device 303 of the syringe pump 201 is correct or not, and ii. wherein the switching element 506 and the device 500 interact such that when a voltage U5 is applied to the resistance track, the current IR5 flowing through the resistance track is dependent on the electrical conductivity of the switching element 506.

2. Device according to claim 1, wherein the device 500 comprises an electrical component 505, wherein the electrical component is connected in parallel to the switching element 506.

3. Device according to claim 2, wherein the conductivity of the switching element 506 changes in the case of a proper clamping of the syringe plunger 201 of the syringe 300 into the holding device 303 of the syringe pump 201 such that the electrical component is bridged.

4. Device according to one of the preceding claims, wherein the electrical component has an electrical resistance R505 > 0.

5. Device according to one of the preceding claims, wherein the applied voltage U5 is a direct voltage or an alternating voltage.

6. Medical treatment system 200 comprising a device according to one of claims 1 to 5.

7. The medical treatment system 200 of claim 6, wherein the medical treatment system is a renal replacement therapy system.

8. The medical treatment system 200 of claim 7, wherein the renal replacement treatment system is a hemodialysis system, a hemofiltration system, a hemodiafiltration system, or an apheresis system.

9. Medical treatment system 200 according to one of claims 6 to 8 comprising a control device, wherein as a result of the measurement of an electrical voltage and / or an electrical current at one or several measuring points of the device 500 above and / or below a limit value, a status signal is generated by the control device, wherein the status signal is indicative of whether the clamping of the syringe plunger 301 of the syringe 300 in the holding device 303 of the syringe pump 201 is correct or not.

10. The medical treatment system 200 according to claim 9, wherein a treatment on the medical treatment system 200 is enabled, blocked and / or stopped depending on the status signal.

11. Medical treatment system 200 according to one of claims 9 or 10, comprising a display device 204, wherein, depending on the status signal, an indication, a warning, and / or an alarm is output via the display device.

12. Medical treatment system 200 according to one of claims 9 to 11 comprising an acoustic output device 206, wherein depending on the status signal, an indication, a warning, and / or an alarm is output via the acoustic output device 206.

13. A method for detecting the proper clamping of a syringe plunger 301 of a syringe 300 in a holding device 303 of a syringe pump 201 and the position of the holding device 303 of the syringe pump 201, comprising the steps: a. Measuring a voltage and / or a current on a device 500, wherein the device 500 comprises: i. a resistance track 501, ii. an electrical sliding contact 502, configured to slide on the resistance track 501, such that the variable resistors R51 are located between the first end of the resistance track 401 and the sliding contact 502 and R52 are located between the second end of the resistance track 501 and the sliding contact 502, wherein the device 500 is configured such that a change in the position of the syringe plunger 301 of the syringe 300, which is inserted into the syringe pump 201, causes a change in the position of the sliding contact 502 on the resistance track 501, iii. a switching element 506, b. closing on the position of the holding device and / or the proper clamping of the syringe plunger 301 i.wherein the device 500 and the switching element 506 interact such that the electrical conductivity of the switching element 506 changes depending on whether the clamping of the syringe plunger 301 of the syringe 300 in the holding device 303 of the syringe pump 201 is correct or not, and wherein the switching element 506 and the device 500 interact such that when a voltage U5 is applied to the resistance track, the current IR5 flowing through the resistance track is dependent on the electrical conductivity of the switching element 506.

14. The method according to claim 13, wherein as a result of the measurement of an electrical voltage and / or an electrical current across an electrical component of the device 500 above and / or below a limit value, a status signal is generated by a control device, the status signal being indicative of whether the clamping of the syringe plunger 301 of the syringe 300 in the holding device 303 of the syringe pump 201 is correct or not.

15. Module with control device comprising a device according to one of claims 1 to 5.

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