An access system for a medical device for dispensing medical fluids, a monitoring system comprising the access system, and a medical treatment device comprising the monitoring system.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FRESENIUS MEDICAL CARE DEUTSCHLAND GMBH
- Filing Date
- 2021-10-05
- Publication Date
- 2026-08-03
Smart Images
Figure 0007899170000002 
Figure 0007899170000003 
Figure 0007899170000004
Abstract
Description
[Technical Field]
[0001] The present invention relates to an access system for a medical device, the system having a housing body with an inner pipe portion formed for transporting medical fluids, the inner pipe portion being surrounded by an outer pipe portion to form an open space for receiving disinfectant fluids, and the housing body having an opening that can be closed by a closure element. The present invention also relates to a monitoring system comprising the access system, and a medical treatment device comprising the monitoring system. The present invention also relates to a method for monitoring an access system for a medical device. [Background technology]
[0002] In medical technology, access systems are used to enable sterile connections of hose lines for the supply or withdrawal of fluids. These types of access systems are also called ports.
[0003] In a hemodialysis machine set up for hemodialysis filtration, the patient's blood is diluted by adding a replacement fluid. The replacement fluid may be provided in a container or obtained from the dialysate via a sterile filter in the dialysis machine. Hemodialysis machines are known to have an access system to which hose lines are connected so that the replacement fluid provided by the dialysis machine can be supplied to an extracorporeal circuit. When not in use, the access system is tightly closed with a closure cap to avoid contamination. The closure cap is removed before connecting the hose lines. With regard to the access system, care must be taken to prevent bacteria or pathogens that may adhere to the access system during routine operation from entering the patient's blood. For this reason, the access system is generally washed with a disinfectant. The disinfectant may be a heated, and therefore bactericidal fluid (dialysate, replacement fluid, RO water) provided by the dialysis machine. Alternatively, chemical disinfectants may be used. To eliminate contamination, it is essential to wash all parts of the access system that may come into contact with the patient with the disinfectant. After disinfection, care should be taken to ensure that no disinfectant residue remains to prevent blood from coming into contact with the disinfectant. In general, the present invention can be used to identify any conductive fluid residue, such as replacement solution residue, which can also be used to flush or fill extracorporeal blood circuits.
[0004] The access system can be disinfected during the shift before each dialysis procedure. However, for cost and time reasons, disinfection at the dialysis center may only be performed before or after each shift (e.g., at night). Therefore, it is especially important to avoid contamination that may result from handling the device during the shift and to perform or prevent further disinfection if necessary. It is also important to determine whether critical parts of the access system come into contact with the disinfectant during disinfection. Checking the airtightness of the access system is also important, particularly during its intended use, i.e., when replacement solution is provided. [Overview of the project]
[0005] An object of the present invention is to provide an access system for medical devices, particularly for dialysis machines, and particularly for drawing out medical fluids, such as replacement fluids, which enable reliable monitoring of their proper condition during and after disinfection. Furthermore, an object of the present invention is to provide a monitoring system comprising the access system, and a medical treatment device comprising the monitoring system, which enables reliable monitoring of its proper condition during and after disinfection. Another object of the present invention is to provide a method for monitoring an access system for a medical device, which enables reliable monitoring of the access.
[0006] These objectives are achieved in accordance with the present invention by the features described in the independent claims. The dependent claims relate to preferred embodiments of the present invention.
[0007] The access system according to the present invention for medical devices has a housing body formed with an inner pipe portion for transporting medical fluids, which is surrounded by an outer pipe portion to form an open space for receiving disinfectant fluids, and the housing body has an opening that can be closed by a closing element.
[0008] The access system according to the present invention is particularly intended to draw out a medical fluid. However, the access system can also be used to supply a medical fluid. Accordingly, the opening of the housing body can be used for the withdrawal or supply of the medical fluid. The pharmaceutical fluid can be, for example, a replacement fluid. The housing body enables the access system to be attached to a medical device, for example a medical treatment device, particularly a hemodialysis machine. When a hose line is connected to the access system, a medical fluid, for example a replacement fluid, flows through the inner pipe portion. During disinfection, the disinfection fluid flows through the empty space closed by the closing element for fluid sealing, and thus the disinfection fluid cleans the area around the relevant part of the access, particularly the area around the inner pipe portion.
[0009] The access system according to the present invention is characterized in that a measurement electrode and a counter electrode are arranged within the housing body such that the measurement electrode interacts with at least one counter electrode via an empty space. The measurement electrode enables an electrical signal to be coupled in or input so that it can evaluate the current flowing between the measurement electrode and the counter electrode, or the voltage applied between the measurement electrode and the counter electrode. In this context, the evaluation of the current and voltage also means the measurement of (complex) resistance (impedance or reactance measurement). Based on the evaluation of the current or voltage (complex resistance), the presence or absence of fluid or moisture in the empty space can be inferred, and / or conclusions can be drawn regarding whether a specific fluid is present in the empty space, which means that one fluid can be distinguished from another fluid.
[0010] If the presence of fluid in the empty space is inferred during the disinfection of the access system, it can be assumed that the empty space is at least partially filled with a disinfectant. In order to monitor the complete filling of the empty space with the disinfection fluid or to identify a partial filling only (filling level), a plurality of counter electrodes can be provided, each of which is associated with a specific region or part of the empty space.
[0011] Since moisture forms a conductive connection between the measuring electrode and the counter electrode, after the access system has been disinfected, it can be checked whether moisture is still present in the empty space, i.e., whether moisture is still present in the port. In fact, it has been shown that most bacteria bind to moisture, so a dry port is generally assumed to be sterile.
[0012] In a preferred embodiment, the access system includes a connector that can be inserted into an opening to draw out or supply medical fluid, the connector having a pipe portion extending into a free space, the portion of which may be connected to a fluid seal in an inner pipe portion of a housing body, and the connection point between the pipe portion of the housing body and the pipe portion of the connector is located in the free space.
[0013] The airtightness of the access system can be checked during operation. If fluid is found in an empty space that should be dry, it can be concluded that there is a leak at the connection point between the pipe portion of the housing body and the pipe portion of the connector, which is located within the empty space.
[0014] In another preferred embodiment, the measuring electrode is a pin extending into a void, electrically insulated from the housing body. The pin may have an electrical connection on the housing side.
[0015] In a particularly preferred embodiment, the counter electrode is formed by at least a portion of the inner pipe section. This embodiment is advantageous for identifying fluids that may leak at the connection point between the pipe section of the housing body and the pipe section of the connector, particularly displacement fluids. In this embodiment, at least a portion of the inner pipe section may be made of a conductive material, or at least a portion of the outer wall of the inner pipe section may be provided with a coating made of a conductive material.
[0016] In a particularly preferred embodiment, at least one counter electrode is formed by at least a portion of the outer pipe section. This embodiment is advantageous when identifying the filling of the empty space with disinfectant fluid. In this embodiment, at least a portion of the outer pipe section may be made of a conductive material, or at least a portion of the inner wall of the outer pipe section may be provided with a coating made of a conductive material. Depending on the level of filling of the empty space with disinfectant fluid, different resistances are set between the measuring electrode and the counter electrode. The more the empty space is filled, the more current paths are formed, and therefore the resistance decreases. If multiple counter electrodes are formed on the outer pipe section, the counter electrodes may be arranged such that specific conductive paths are formed to each individual counter electrode, depending on the level of filling. In both cases, monitoring can be performed by corresponding evaluation of the signal, for example, by deviation from a reference value.
[0017] The access system may also have both embodiments, so that one or more current paths between the measuring electrode and the inner and outer pipe portions can be detected.
[0018] A monitoring system according to the present invention, comprising an access system according to the present invention, includes means for generating an electrical signal, which is electrically connected to a measuring electrode and at least one counter electrode, and evaluation and calculation means configured to evaluate the current flowing between the measuring electrode and at least one counter electrode, or the voltage applied between the measuring electrode and at least one counter electrode.
[0019] The evaluation and calculation means may be configured to evaluate the current flowing between the measuring electrode and at least one counter electrode, or the voltage applied between the measuring electrode and at least one counter electrode, so as to infer the presence or absence of fluid or moisture in the empty space, or to identify whether a particular fluid is present in the empty space. Known evaluation methods can be used to determine the state of the access system.
[0020] The evaluation and calculation means may be configured to generate a control signal or reporting signal when fluid or moisture is inferred to be present in the empty space, and / or when no fluid or moisture is inferred to be present in the empty space. The control signal or reporting signal may be used, for example, to intervene in the mechanical control of a medical device, for example, to prevent further action, or to issue an alarm. The operator may be prompted on the display to perform disinfection.
[0021] If the ground connection of the counter electrode is faulty, especially if the ground connection is interrupted, an increase in leakage current may occur. Therefore, the means for generating the electrical signal is preferably configured so that the electrical signal is generated at continuous time intervals. Since the measurement signal is applied for only a short time, the average current is lower than in the case of continuous application.
[0022] For safety reasons, a coupling capacitor may be provided between the evaluation and calculation means and the measuring electrode.
[0023] In another preferred embodiment, the means for generating an electrical signal includes a frequency generator for generating an AC voltage signal or an AC current signal.
[0024] The evaluation and calculation means may have means for rectifying an AC voltage signal, and the evaluation and calculation means is configured so that the rectified AC voltage signal (DC voltage) is compared to a reference value. Then, if the rectified AC voltage signal is smaller than the reference value, the presence of fluid or moisture in the empty space can be inferred. The filling level can be inferred based on the DC voltage level, i.e., based on electrical resistance.
[0025] However, in order to identify a specific fluid, such as a displacement fluid, it is also possible to evaluate the unrectified AC voltage signal / AC current signal generated when excited by an AC voltage through a conductive connection between the measuring electrode and the counter electrode, which is formed by the fluid / moisture. Methods for evaluating the signal can be found in the prior art. See DE 10 2010 028 902 A1 for this.
[0026] Embodiments of the present invention will be described in detail below with reference to the following drawings. [Brief explanation of the drawing]
[0027] [Figure 1] This is a greatly simplified schematic diagram of a hemodialysis apparatus according to the present invention, and the hemodialysis apparatus has a monitoring system according to the present invention that includes an access system according to the present invention. [Figure 2] This is a cross-sectional view of one embodiment of the access system according to the present invention. [Figure 3] One embodiment of the monitoring system according to the present invention is shown. [Figure 4] An electrical equivalent circuit diagram illustrating the flow of current is shown. [Figure 5] This shows the time curve of an AC voltage signal. [Figure 6] This shows the attenuation of an AC voltage signal as a function of frequency. [Figure 7] This document shows one embodiment of the evaluation and calculation means for a monitoring system. [Figures 8A-8D] [Modes for carrying out the invention]
[0028] As an example of a medical treatment device 1, Figure 1 is a greatly simplified schematic diagram of an in vitro blood treatment device having a monitoring system 2 for monitoring access to the medical treatment device.
[0029] The external blood treatment device is a hemodialysis (dialysis) filtration device having a dialyzer 3 separated by a semipermeable membrane 4 into a blood chamber 5 through which blood flows and a dialysis fluid chamber 6 through which dialysis fluid flows. The blood chamber 5 is part of the extracorporeal blood circuit I, and the dialysis fluid chamber 6 is part of the dialysis fluid system II of the hemodialysis (dialysis) filtration device.
[0030] The extracorporeal blood circuit I comprises an arterial blood line 7 leading to the inlet 5a of the blood chamber 5 and a venous blood line 8 branching from the outlet 5b of the blood chamber 5 of the dialyzer 3. The patient's blood is delivered through the blood chamber 5 of the dialyzer 3 by an arterial blood pump 9 positioned on the arterial blood line 7. The blood lines 7, 8 and the dialyzer 3 form a disposable item intended for single use, inserted into the dialyzer for dialysis procedures.
[0031] New dialysis fluid is supplied from the dialysis fluid source 10. A dialysis fluid supply line 11 runs from the dialysis fluid source 10 to the inlet 6a of the dialysis fluid chamber 6 of the dialyzer 3. A dialysis fluid discharge line 12 runs from the outlet 6b of the dialysis fluid chamber 6 to the drain 13. A dialysis fluid pump 14 is connected to the dialysis fluid discharge line 12.
[0032] During dialysis, a replacement fluid (replacement solution) may be supplied to the extracorporeal blood circuit I via a replacement fluid line 15b. In this embodiment, the replacement fluid line 15b is connected to a portion of the arterial blood line 7. The replacement fluid may be a fluid supplied at a replacement fluid source 16 and may be carried by a replacement fluid pump 17. The replacement fluid source 16 may be a container filled with prepared replacement fluid. In one embodiment, the replacement fluid may also be generated by filtering dialysate from a dialysis fluid source 10 in an extracorporeal blood treatment device through a sterile filter (not shown in Figure 1).
[0033] The replacement fluid line 15b is part of a disposable product intended for single use. To connect the replacement fluid line 15b to the blood treatment device, an access system P (port) (illustrated schematically only in Figure 1) is provided in the housing 1A of the blood treatment device 1 (the housing is illustrated only in Figure 1). A fluid connection section 15a is provided, in particular, to connect the replacement fluid supply source 16 to the access system P.
[0034] The access system P can be disinfected before or after a dialysis procedure, or at specific time intervals, for example, once a day. In this embodiment, the disinfectant fluid for disinfecting the access system P is provided in a container 18, which can be used instead of the replacement fluid supply source 16. To carry out disinfection, the disinfectant fluid is connected to the access system P via a fluid connection 15a. During disinfection, the access system P is flushed with the disinfectant fluid, which is done by the disinfectant fluid being guided from the container 18 to the access system P and then removed from there via a drain line or return line 19.
[0035] The blood treatment device 1 has a monitoring system 20 (shown only in Figure 1) for monitoring the status of the access system.
[0036] The embodiment of access system P (port) will be described in detail below with reference to Figure 2.
[0037] The access system P has a multi-component housing body 21 attached to the housing 1A of the blood treatment device 1 so that it is freely accessible to an operator. An inner pipe section 22 for transporting replacement fluid or disinfectant fluid is formed within the housing body 21. The inner pipe section 22 is surrounded by an outer pipe section 24 (tapering to the right in Figure 2) to form an open space 23 for receiving disinfectant fluid. To draw out the replacement fluid, the housing body 21 has an opening 25 that can be closed by a closing element (not shown in Figure 2). At the outer end of the inner pipe section 22 is a connection section 26 for a fluid connection section 15a leading to a replacement fluid supply source 16 or disinfectant fluid container 18 (Figure 1).
[0038] A suitable connector 27 can be inserted into the opening 25 to draw out the displacement fluid. The connector 27 has an inner pipe portion 28A that extends into the empty space and is fluid-sealed to the inner pipe portion 22 of the housing body 21 when the connector 27 is connected. The inner pipe portion 28A is surrounded by a touch guard 28B. The opening formed by the inner pipe portion 28A and the opening formed by the touch guard 28B are not in the same plane and are spaced apart from each other so that it is difficult or impossible to touch the inner pipe portion 28A of the connector 27. The connection point 29 between the pipe portion 22 of the housing body and the pipe portion 28A of the connector 27 is located approximately in the center of the empty space 23.
[0039] The disinfectant flows into the empty space 23 via a connection 26 connected to the disinfectant container 18. The disinfectant is drained through a channel 38b connected to a drain line or return line 19 (Figure 1). The disinfectant drained or moved from the empty space 23 may be collected in a further container (not shown in Figure 1) and then disposed of, or discarded via the drain.
[0040] To better remove disinfectant from the empty space 23, sterile air may be directed into the empty space through the opening 38A. The sterile air is compressed, for example, by a compressor and directed into the empty space 23. This compressed air may be used to move any existing fluid from the empty space, for example, through the opening 38B.
[0041] The access system P has a measuring electrode 30. In this embodiment, the measuring electrode 30 is a pin electrically insulated from the housing body 21. The pin-shaped measuring electrode 30 is set in a receiving component 30A made of an insulating material (e.g., PEEK), which is inserted into the housing body 21. One end of the pin-shaped measuring electrode 30 extends into the open space 23, while the other end extends outward from the housing body 21 for connecting a wire.
[0042] The measuring electrode 30 is positioned to interact with at least one counter electrode 31, 32 via the empty space 23. At least a portion of the inner pipe portion 22 functions as the first inner counter electrode 31, and at least a portion of the outer pipe portion 24 functions as the second outer counter electrode 32. For this purpose, at least a portion of the inner pipe portion 22 may be made of a conductive material, or at least a portion of the outer wall of the inner pipe portion 22 may be provided with a coating 22A made of a conductive material. Correspondingly, at least a portion of the outer pipe portion 24 may be made of a conductive material, or at least a portion of the inner wall of the outer pipe portion 24 may be provided with a coating 24A made of a conductive material. In this embodiment, the outer wall of the inner pipe portion 22 is provided with a coating 22A, and the inner wall of the outer pipe portion 24 is provided with a coating 24A made of a conductive material.
[0043] The monitoring system 2 includes means 33 for generating electrical signals and evaluation and calculation means 34, which are schematically shown in Figure 3 along with the access system P and patient access 35. Figure 3 shows only the inner pipe portion 22 and the outer pipe portion 24 of the access system P.
[0044] The means 33 for generating an electrical signal generates an AC voltage signal V of a specified frequency. ac The system includes a controllable frequency generator 33A that generates a sine wave signal with a frequency of, for example, 20 kHz. The frequency generator 33A can be controlled by a control device (CPU1). The AC voltage can be generated by, for example, a VCO (voltage-controlled oscillator) or an adjustable signal generator. The CPU1 can be designed, for example, as a programmed microcontroller.
[0045] Means 33 for generating electrical signals and evaluation and calculation means 34 are connected to the measuring electrode 30 via an electrical connection line 35. A first switch 36 is provided that can be opened and closed by a control signal en_meas from a second control device (CPU 2) to disconnect the electrical connection. Furthermore, a reference resistor R Ref A reference resistor R is provided, which establishes a connection between the connection line 35 and ground when the second switch 37 is closed. The second switch 37 can be opened and closed by the control signal set_ref from the CPU 2. Ref This is used to check the operation of the circuit described below.
[0046] For safety reasons, a coupling capacitor C is provided within the connection line 35, and this capacitor can be designed as a Y capacitor. The Y capacitor provides high dielectric strength, ensuring that dielectric breakdown of the capacitor and therefore dangerous voltages at the measuring electrodes are prevented.
[0047] According to the present invention, an electrical signal is applied to the measuring electrode 30. This can be any voltage having any voltage curve, in particular an AC voltage. If the conductive path between the measuring electrode 30 and the counter electrodes 31, 32 is provided by fluid residue, the flow of current in the current path between the measuring electrode and the counter electrode or the voltage drop across the resulting resistance between the measuring electrode and the counter electrode can be measured.
[0048] To avoid leakage current, the pipe portion 22 (or 22A) that functions as at least one counter electrode 31 is grounded, as shown in FIG. 3. For example, when a plurality of counter electrodes are used as in FIG. 2 (24 or 24A), these are also grounded. If the ground is faulty or interrupted (illustrated in FIG. 3), a relatively high leakage current may occur, which may endanger the patient P. This must be avoided by all means.
[0049] During dialysis treatment, the replacement fluid flowing in the fluid connection portion 15a and the replacement fluid line 15b contains conductive ions and establishes a direct conductive fluid connection to the patient's vascular system. For example, in acute dialysis, in a patient having a central venous catheter as access to the vascular system, the catheter is located close to the heart in order to ensure a sufficiently high blood flow rate in the extracorporeal blood circuit. Especially for such patients, the high leakage current that may occur due to the capacitive coupling between the dialysis machine and the patient's fluid path must be avoided by all means.
[0050] An increase in leakage current can occur when there is an interruption in the ground connection of the counter electrode 31, as shown in FIG. 3. Leakage at the connection point 29 of the inner housing side pipe portion 22 and the inner connector side pipe portion 28A may lead to a conductive fluid connection between the measurement electrode 30 and the patient's vascular system, and as a result, a current i p occurs. The larger this current is, the worse the ground connection of the counter electrode becomes.
[0051] FIG. 4 shows an electrical equivalent circuit diagram for illustrating this relationship. The total current i is limited by the internal resistor R i of the source and the parallel connection of the individual resistors (impedances) Z sc1 +Z gnd and Z sc2 +Z sub +Z p In the example of FIG. 4, R i is R fb(Figure 7) and the output resistor (not shown) of the operational amplifier OP1 at the input of the evaluation and calculation means 34, which will be described in detail below. The coupling capacitor C is either ignored or sized so that it has no relevant effect. Z scl Z is the impedance resulting from the conductive bridge between the measuring electrode and the counter electrode. gnd Z is the impedance resulting from the electrical connection between the counter electrode and the protective conductor PE, and here we can assume it is a purely ohmic cable connection. sc2 This is the impedance arising from the conductive bridge between the measuring electrode 30 and a possible leakage point in the port at the connection point 29, for example, the inner housing side pipe portion or the connector side pipe portion. sub This is the impedance of the conductive fluid connection in the displacement fluid line, and this connection depends on the length and diameter of the displacement fluid line 15b (hose line), as well as the ion content of the displacement fluid. p This is the impedance resulting from the connection between the exit point of the replacement fluid in the patient's vascular system and the patient's ground, which depends, for example, on the patient's position and size or the patient's clothing. For example, the patient may be in contact with a grounded metal object. The above variable may be a complex variable.
[0052] current i p In particular, its size is a significant risk factor for patients. Earth connection Z gnd If the ground connection of the counter electrode is faulty, i.e., the current path on the left side of Figure 4 is interrupted, the current i no longer branches into two paths but flows only through the path on the right side and therefore flows to the patient. Even if the ground connection of the counter electrode is faulty, i.e., interrupted, the health risk is eliminated so that the current i p It must be ensured that the magnitude does not exceed 50 μA (effective). According to the present invention, the increase in leakage current can be prevented by the following measures, which can be used individually or in combination.
[0053] Excitation voltage V acThe means 33 for generating the excitation voltage V ensures that no leakage current greater than 50 μA flows even in the event of a malfunction. ac It can be configured so that its size is limited.
[0054] Furthermore, the excitation voltage V ac The means 33 for generating the excitation voltage V may be configured so that a pulse-like measurement is performed. ac The voltage is applied for a short period and then switched off so that it is applied again periodically. On average, the result is a smaller current than when the excitation voltage is applied continuously.
[0055] Figure 5 shows the sinusoidal excitation voltage V at a frequency of 20 kHz. ac The time curve is shown. Excitation voltage V ac is a time interval T on The voltage is applied. In order to apply the AC voltage, CPU1 generates a control signal en_meas so that the first switch 36 is closed.
[0056] Effective leakage current I peff It is calculated using the following formula:
number
[0057] The signal can be evaluated, and safety is not compromised by excessive "timeouts," and the effective leakage current I peff The time ratio T remains below the limit value. on / T total This is specified.
[0058] Furthermore, the excitation voltage V ac The means 33 for generating the excitation voltage V acThe minimum frequency can be specified. Figure 6 shows that the impedance resulting from the current path on the right (Figure 4), which is very important for the level of leakage current, increases with increasing frequency. Consequently, the signal attenuation D also increases with increasing frequency f. The excitation frequency is selected depending on the boundary conditions and the attenuation behavior shown in Figure 6, so that even in the event of a fault, the leakage current cannot exceed a limit, e.g., 20 kHz.
[0059] The evaluation and calculation means 34 has a circuit for measuring and processing the measurement signal. Figure 7 shows an embodiment of this circuit, which includes three stages A1, A2, and A3, each having operational amplifiers OP1, OP2, and OP3, respectively.
[0060] The first stage A1 is a feedback resistor R fb It acts as a buffer that uses the electrical signal V generated by means 33. ac The (AC voltage) is applied to the + input of OP1. The measuring electrode 30 is connected to the - input of OP1 via a coupling capacitor C. Impedance Z sc The (short circuit) is a conductive bridge caused by fluid or moisture between the measuring electrode 30 and the counter electrodes 31 and 32, which in this example are on the reference potential PE, i.e., protective earth. This is a characteristic current i sc Set the following. The detected fluid or moisture generally represents not pure ohmic resistance, but rather mixed ohmic and reactance impedance (capacitive or inductive). Therefore, the above variable can be a complex variable. As a result, the current i sc Generally, AC voltage V ac The phase is shifted. In one embodiment, this can be used not only to detect the presence of fluid or moisture in the port, but also to draw conclusions about the type of fluid. For example, blood has a characteristic complex resistance that is different from, for example, water.
[0061] If there is no conductive bridge between the measuring electrode 30 and the counter electrodes 31 and 32, the current i sc No current flows. In this case, the voltage of the + input, i.e., Vac The same voltage is applied to the feedback resistor R. fb It exists at the negative input of OP1 via R. In this case, the current is R fb Since no current flows (the input resistance of Al can be considered to be extremely high with good approximations), the output voltage of OP1 is also V ac That is the case.
[0062] However, current i caused by fluid or moisture sc If R flows, fb and Z sc This forms a voltage divider from the output of OP1 to the PE reference potential (the effects of the coupling capacitor C1 and the measuring electrode can be ignored in the operating frequency range). As a result, the voltage at the - input of OP1 decreases, but OP1 is R fb In its capacitance as a differential amplifier fed back through, the output voltage is increased to such an extent that the + and - inputs of OP1 have the same voltage. Therefore, V ac The voltage and i sc *Z sc The sum of these is set as the output of OP1. This voltage or the transient characteristics of the voltage indicate the characteristics of moisture present in the port that forms a conductive connection between the measuring electrode and the counter electrode. In step A2, this voltage is rectified, averaged, or smoothed, and in step A3, the measured voltage is amplified. Rectifier and amplifier circuits can be found in the prior art. The result is a voltage V that can be digitized by an analog-to-digital converter (not shown). adc That is the case.
[0063] For example, an evaluation and calculation means 34, which may include a controller CPU 1 (Figure 3), is configured to evaluate the measurement signal using the calculation operations described below to identify whether a fluid or moisture is located in the empty space and / or which fluid is located in the empty space. For this purpose, algorithms known to those skilled in the art can be used. If a fluid or moisture located in the empty space 23 is inferred, the evaluation and calculation means generates a control signal or a reporting signal.
[0064] Figures 8A to 8D show the time curves of the signals. CPU1 generates the signal en_meas so that the first switch 36 (Figure 3) is closed (Figure 8A). At this point, the excitation voltage V ac For example, an AC voltage with a frequency of 20 kHz is generated (Figure 8B). Each of the signals in Figures 8C and 8D shows the characteristics of the resulting voltage Ana_in, which is evaluated by CPU2.
[0065] Figure 8C shows the case where the port is dry (no CD detection), and Figure 8D shows the case where a conductive connection is formed between the measuring electrode and the counter electrode due to moisture (CD detection). In the second case, the resulting voltage Ana_in is higher, which is the reference value V Ref It can be appropriately detected by comparison with the reference value V. In this example, in CPU1 (controller), the measured voltage is A / D converted, and the voltage Ana_in is set to the reference value V. Ref This is compared to [another method]. However, it is also possible to evaluate the resulting voltage Ana_in using a simple (analog) comparator. If there is no excitation signal and the measuring electrode 30 is not conductively connected to the circuit, the voltage cannot be measured either, and this can also be checked by the circuit.
[0066] The first switch 36, controlled by the en_meas signal, preferably has an excitation voltage V ac The circuit is open at time intervals when it is not intended to apply current to the measuring electrode. As a result, the measuring electrode 30 is isolated from the circuit, thus preventing undesirable leakage current.
[0067] After interrupting the current path to the coupling capacitor C by opening the first switch 36, and after connecting the reference resistor Rref by closing the second switch 37 (en_meas=off, set_ref=on), the expected value of the voltage Ana_in can be checked. If the measured value deviates from the expected value, an error exists. Figures 8C and 8D show the upper limit reference value V Ref 1 and lower limit reference value V Ref 2 is shown. For example, the voltage is the upper limit reference value VRef 1 and lower limit reference value V Ref It can be checked whether it is between 2 and 3.
[0068] Based on the level of the voltage Ana_in or an electrical variable correlated with the voltage, it may also be determined whether and to what extent the empty space is filled with fluid. This is particularly advantageous for checking the disinfection process.
[0069] The inner pipe portion 22 or the outer pipe portion 24 can function as counter electrodes 31, 32. To check the filling level, at least a portion of the outer pipe portion 24 may be designed as an alternative or additional counter electrode 32, for example, by providing a conductive coating 24A on a specific region of the inner wall of the outer pipe portion 24, so that multiple current paths can be formed from the measuring electrode to individual regions. Then, depending on the filling level of the disinfectant fluid in the empty space, different resistances are set, and as the filling level of the empty space increases, further current paths are formed, thereby decreasing the resistance, which can be identified using the evaluation and calculation means 34. If multiple counter electrodes are provided, the evaluation and calculation means 34 may also be configured to evaluate multiple measurement signals. Depending on the filling level, voltage or current values can be obtained for each individual counter electrode, and these values can be compared to a reference value that characterizes a particular filling level.
[0070] In the embodiments described above, a substantially rectified signal Ana_in is evaluated, resulting in a loss of information regarding the phase shift between the measured signal and the excitation signal. However, it is also possible to evaluate an unrectified AC voltage / AC current signal. If the measurement is performed not only at the excitation frequency but also by changing the frequency (frequency sweep), a characteristic curve is produced, which can be converted, for example, into an impedance curve (the magnitude of impedance as a function of frequency). For example, in the case of blood, the structure (cells in plasma) results in specific current paths and corresponding impedances depending on the measurement frequency. In this regard, please refer to DE 10 2010 028 902 A1, in particular Figures 1-4 and their related descriptions. Thus, it is possible to determine what the fluid is by a method known from DE 10 2010 028 902 A1 and using the monitoring system 2 according to the present invention. Dialysis fluids or replacement fluids have different characteristic impedance curves due to their composition (not containing cells), and can also differ from one another in terms of, for example, ion density, i.e., density of free charge carriers. The invention described in the claims of the original application is listed below. [1] Access system for a medical device, the system having a housing body formed with an inner pipe portion for transporting a medical fluid, the portion being surrounded by an outer pipe portion to form an open space for receiving a disinfectant fluid, the housing body having an opening that can be closed by a closing element, The measuring electrode and the at least one counter electrode are arranged within the housing body such that the measuring electrode interacts with at least one counter electrode through the empty space, Access system. [2] The access system according to [1], characterized in that the measuring electrode is a pin that extends into the empty space and is electrically insulated from the housing body. [3] The access system according to [1], characterized in that the at least one counter electrode is formed by at least a portion of the inner pipe portion. [4] The access system according to [3], characterized in that at least a portion of the inner pipe portion is made of a conductive material, or at least a portion of the outer wall of the inner pipe portion is provided with a coating made of a conductive material. [5] The access system according to any one of [1] to [4], characterized in that the at least one counter electrode is formed by at least a portion of the outer pipe portion. [6] The access system according to [5], characterized in that at least a portion of the outer pipe portion is made of a conductive material, or at least a portion of the inner wall of the outer pipe portion is provided with a coating made of a conductive material. [7] The access system according to any one of [1] to [6], wherein the access system comprises a connector that can be inserted into the opening, the connector having a pipe portion that extends into the empty space and can be connected to the inner pipe portion of the housing body in a fluid seal, and the connection point between the inner pipe portion of the housing body and the pipe portion of the connector is located in the empty space. [8] A monitoring system comprising an access system as described in any one of [1] to [7], wherein the monitoring system has means for generating an electrical signal, the means being electrically connected to the measuring electrode and the at least one counter electrode, and the monitoring system has evaluation and calculation means configured to evaluate a current flowing between the measuring electrode and the at least one counter electrode, or a voltage applied between the measuring electrode and the at least one counter electrode. [9] The monitoring system according to [8], characterized in that the evaluation and calculation means is configured to evaluate the current flowing between the measuring electrode and the at least one counter electrode, or the voltage applied between the measuring electrode and the at least one counter electrode, so as to infer the presence or absence of fluid or moisture in the empty space.
[10] The monitoring system according to [9], characterized in that the evaluation and calculation means is configured to generate a control signal or a report signal when a fluid or moisture located in the empty space is estimated, and / or when a fluid or moisture located in the empty space is not estimated.
[11] The monitoring system according to any one of [8] to
[10] , characterized in that the evaluation and calculation means is configured to evaluate a current flowing between the measuring electrode and the at least one counter electrode, or a voltage applied between the measuring electrode and the at least one counter electrode, so that a conclusion can be drawn regarding whether a particular fluid is present in the empty space.
[12] The monitoring system according to any one of [8] to
[11] , characterized in that the means for generating electrical signals is configured such that the electrical signals are generated at continuous time intervals.
[13] The monitoring system according to any one of [8] to
[12] , characterized in that the means for generating an electrical signal has a frequency generator for generating an AC voltage signal or an AC current signal.
[14] The monitoring system according to
[13] , wherein the evaluation and calculation means has means for rectifying an AC voltage signal, the evaluation and calculation means is configured such that the rectified AC voltage signal is compared with a reference value, and the presence of fluid or moisture in the empty space is inferred when the rectified AC voltage signal is outside the reference value. A medical treatment device having a monitoring system as described in any one of the items
[15] [8] to
[14] .
[16] The medical treatment device according to
[15] , wherein the medical treatment device is a blood treatment device having an extracorporeal blood circuit, the device having means for providing replacement fluid, and the inner pipe portion is in fluid communication with the means for providing replacement fluid.
[17] A method for monitoring an access system for a medical device, the system comprising a housing body having an inner pipe portion formed for transporting a medical fluid, the portion being surrounded by an outer pipe portion to form an open space for receiving a disinfectant fluid, the housing body having an opening that can be closed by a closure element, A method characterized in that a current flowing between the measuring electrode and the at least one counter electrode, or a voltage applied between the measuring electrode and the at least one counter electrode, is evaluated by a measuring electrode interacting with the at least one counter electrode through the empty space, such that an electrical signal is coupled in and an inference is drawn about the presence or absence of fluid or moisture in the empty space, and / or a conclusion is drawn about whether a particular fluid is present in the empty space.
[18] The method according to
[17] , characterized in that the measuring electrode is a pin that extends into the empty space and is electrically insulated from the housing body.
[19] The method according to
[17] or
[18] , characterized in that the at least one counter electrode is formed by at least a portion of the inner pipe portion and / or by at least a portion of the outer pipe portion.
[20] The method according to any one of
[17] to
[19] , characterized in that the electrical signals are coupled in at continuous time intervals.
[21] The method according to any one of
[17] to
[20] , characterized in that the electrical signal is coupled in via a coupling capacitor.
[22] The method according to
[17] , characterized in that the electrical signal is an AC voltage having a specified frequency, or the electrical signal is an AC voltage having a frequency that changes over time (frequency sweep).
Claims
1. An access system for a medical device, the system having a housing body formed with an inner pipe portion for transporting medical fluid, the portion being surrounded by an outer pipe portion to form an open space for receiving disinfectant fluid, the housing body having an opening that can be closed by a closing element, The measuring electrode and the at least one counter electrode are arranged within the housing body such that the measuring electrode interacts with at least one counter electrode through the empty space. The measuring electrode and the at least one counter electrode are configured such that an electrical signal can be supplied so that the current flowing between the measuring electrode and the at least one counter electrode, or the voltage applied between the measuring electrode and the at least one counter electrode, can be analyzed. The aforementioned empty space is separate from the main fluid transport path passing through the inner pipe portion, and the electrode is configured to detect the presence or absence of fluid or moisture in the empty space. Access system.
2. The access system according to claim 1, characterized in that the measuring electrode is a pin that extends into the empty space, is electrically insulated from the housing body, and is configured to interact with a fluid potentially present in the empty space.
3. The access system according to claim 1, characterized in that the at least one counter electrode is formed by at least a portion of the inner pipe portion.
4. The access system according to claim 3, characterized in that at least a portion of the inner pipe portion is made of a conductive material, or at least a portion of the outer wall of the inner pipe portion is provided with a coating made of a conductive material.
5. The access system according to any one of claims 1 to 4, characterized in that the at least one counter electrode is formed by at least a portion of the outer pipe portion.
6. The access system according to claim 5, characterized in that at least a portion of the outer pipe portion is made of a conductive material, or at least a portion of the inner wall of the outer pipe portion is provided with a coating made of a conductive material.
7. The access system according to any one of claims 1 to 6, wherein the access system comprises a connector that can be inserted into the opening, the connector having a pipe portion that extends into the empty space and can be connected to the inner pipe portion of the housing body in a fluid seal, the connection point between the inner pipe portion of the housing body and the pipe portion of the connector is located in the empty space, and the integrity of the fluid at the connection point in the empty space can be monitored.
8. A monitoring system comprising an access system according to any one of claims 1 to 7, wherein the monitoring system has means for generating an electrical signal, the means being electrically connected to the measuring electrode and the at least one counter electrode, and the monitoring system has evaluation and calculation means configured to evaluate a current flowing between the measuring electrode and the at least one counter electrode, or a voltage applied between the measuring electrode and the at least one counter electrode.
9. The monitoring system according to claim 8, characterized in that the evaluation and calculation means is configured to evaluate the current flowing between the measuring electrode and the at least one counter electrode, or the voltage applied between the measuring electrode and the at least one counter electrode, so as to infer the presence or absence of fluid or moisture in the empty space.
10. The monitoring system according to claim 9, characterized in that the evaluation and calculation means is configured to generate a control signal or a report signal when a fluid or moisture located in the empty space is estimated, and / or when a fluid or moisture located in the empty space is not estimated.
11. A monitoring system according to any one of claims 8 to 10, characterized in that the evaluation and calculation means is configured to evaluate the current flowing between the measuring electrode and the at least one counter electrode, or the voltage applied between the measuring electrode and the at least one counter electrode, so as to whether a particular fluid is present in the empty space.
12. The monitoring system according to any one of claims 8 to 11, characterized in that the means for generating electrical signals is configured to generate electrical signals at continuous time intervals.
13. The monitoring system according to any one of claims 8 to 12, characterized in that the means for generating an electrical signal includes a frequency generator for generating an AC voltage signal or an AC current signal.
14. The monitoring system according to claim 13, characterized in that the evaluation and calculation means has means for rectifying an AC voltage signal, the evaluation and calculation means is configured so that the rectified AC voltage signal is compared with a reference value, and the presence of fluid or moisture in the empty space is inferred when the rectified AC voltage signal deviates from the reference value.
15. A medical treatment device having a monitoring system according to any one of claims 8 to 14.
16. The medical treatment device according to claim 15, wherein the medical treatment device is a blood treatment device having an extracorporeal blood circuit, the device has means for providing replacement fluid, and the inner pipe portion is in fluid communication with the means for providing replacement fluid.
17. A method for operating a monitoring system for monitoring an access system for a medical device, wherein the access system has a housing body formed with an inner pipe portion for transporting medical fluid, the portion being surrounded by an outer pipe portion to form an open space for receiving disinfectant fluid, and the housing body has an opening that can be closed by a closing element. An electrical signal is coupled in by a measuring electrode that interacts with at least one counter electrode through the aforementioned empty space. The measuring electrode and the at least one counter electrode are arranged within the housing body such that the measuring electrode interacts with the at least one counter electrode through the empty space. The aforementioned empty space is separate from the main fluid transport path passing through the inner pipe portion, and the electrode is configured to detect the presence or absence of fluid or moisture in the empty space. An operating method characterized in that the monitoring system operates such that the current flowing between the measuring electrode and the at least one counter electrode, or the voltage applied between the measuring electrode and the at least one counter electrode, is evaluated so as to determine whether there is fluid or moisture in the empty space and / or to determine whether a particular fluid is present in the empty space.
18. The operating method according to claim 17, characterized in that the measuring electrode is a pin extending into the empty space and electrically insulated from the housing body.
19. The operating method according to claim 17 or 18, characterized in that the at least one counter electrode is formed by at least a portion of the inner pipe portion and / or by at least a portion of the outer pipe portion.
20. The operating method according to any one of claims 17 to 19, characterized in that the electrical signals are coupled in at continuous time intervals.
21. The operating method according to any one of claims 17 to 20, characterized in that the electrical signal is coupled in via a coupling capacitor.
22. The operating method according to claim 17, characterized in that the electrical signal is an AC voltage having a specified frequency, or the electrical signal is an AC voltage having a frequency that changes over time (frequency sweep).