Access system, monitoring system, medical treatment device and method for monitoring access system of medical device

Abstract

The invention relates to an access system (1) for a medical device, having an outer housing (21) in which an inner tubing section (22) for transporting a medical liquid is formed, which is surrounded by an outer tubing section (24) to form a cavity (23) for accommodating a sterilizing liquid, wherein the outer housing (21) has an opening (25) which can be closed by a closure element. The access system (1) according to the invention is characterized in that a measuring electrode (30) and at least one counter electrode (31, 32) are arranged in the outer housing (21) such that the measuring electrode (30) interacts with the counter electrode via the cavity (23). The measuring electrode (30) allows the feeding in of an electrical signal so that an electrical current flowing between the measuring electrode and the counter electrode or a voltage applied between the measuring electrode and the counter electrode can be evaluated. On the basis of the evaluation of the electrical current or the voltage, it can be concluded whether a liquid is present in the cavity (23) or whether moisture is present in the cavity, and / or it can be concluded whether a specific liquid is present in the cavity (23). Furthermore, the invention relates to a monitoring system (2) having such an access system (1) and a medical device (1) having such a monitoring system (2) as well as a method for monitoring an access system for a medical device.

Description

Technical Field

[0001] This invention relates to an access system for a medical device, the access system having a housing containing internal tubing sections for transporting medical fluids, the internal tubing sections being surrounded by external tubing sections to form a cavity for containing a disinfectant fluid, wherein the housing has openings that can be closed by a sealing element. Furthermore, this invention relates to a monitoring system having such an access system and a medical treatment device having such a monitoring system. Additionally, this invention relates to a method for monitoring the access system of a medical device. Background Technology

[0002] In medical technology, access systems are used to deliver or extract fluids. These systems allow for the aseptic connection of tubing to enable the delivery or extraction of fluids. Such access systems are also known as ports.

[0003] In hemodialysis equipment used for hemodialysis filtration, the patient's blood is diluted by adding a substitute. The substitute can be provided in a container or obtained from the dialysate via a sterile filter within the dialysis unit. Hemodialysis units are known to have an access system to which tubing is connected, enabling the delivery of the substitute provided by the dialysis unit to the extracorporeal circuit. The access system is tightly sealed with a shroud when not in use to prevent contamination. The shroud is removed before connecting the tubing. It is important to note that bacteria or pathogens that may adhere to the access system in routine practice do not enter the patient's bloodstream. Therefore, the access system is generally rinsed with a disinfectant solution. For example, the disinfectant solution can be a heated and thus sterilized liquid (dialysate, substitute, RO water), which can be provided by the dialysis unit. Alternatively, chemical disinfectants can also be used. Importantly, all parts of the access system that may be in contact with the patient are rinsed around with the disinfectant solution to remove contamination. Following disinfection, no disinfectant solution residue is permitted to ensure safety and prevent blood from coming into contact with the disinfectant solution. Generally, this invention can identify any residue of conductive liquids, including, for example, residues of alternative solutions, particularly those used for flushing and filling external blood circuits.

[0004] Disinfection of the access system can be performed during a shift before each dialysis treatment. However, for cost and time reasons, it is also possible to propose that disinfection of the dialysis center be performed only before or after each shift (e.g., at night). Therefore, it is of particular interest to avoid contamination during shifts due to machine operation and to perform further disinfection or prevent further treatment if necessary. It is also of interest to determine during disinfection whether critical parts of the access system come into contact with the disinfectant solution. Checking the seal of the access system is also of interest. Particularly of interest is checking the seal of the access system during routine use, i.e., when providing replacement solutions. Summary of the Invention

[0005] This invention aims to provide an access system for medical devices, particularly dialysis devices, especially for extracting medical fluids, such as substitutes, that allows reliable monitoring of their conformity during and after sterilization. Furthermore, this invention aims to provide a monitoring system and a medical device with such an access system, allowing reliable monitoring of their conformity during and after sterilization. Another object of this invention is to provide a method for monitoring the access system of a medical device, by which the access portion can be reliably monitored.

[0006] According to the present invention, the aforementioned objective is achieved through the features of embodiments of the invention. The following description relates to preferred embodiments of the invention.

[0007] The access system for a medical device according to the invention has a housing containing an internal tubing section for transporting medical fluids, the internal tubing section being surrounded by an external tubing section to form a cavity for containing a disinfectant liquid, wherein the housing has an opening that can be closed by a sealing element.

[0008] The access system according to the invention is particularly designed for extracting medical fluids. However, the access system can also be used to deliver medical fluids. Therefore, the opening in the housing can be used for extracting or delivering medical fluids. For example, the medical fluid can be a substitute. The housing allows the access system to be secured to a medical device, such as a medical treatment device, particularly a hemodialysis device. When the tubing is connected to the access system, the medical fluid, such as a substitute, flows through the internal tubing section. During sterilization, a sterilizing solution flows through a cavity sealed in a fluid-tight manner by a sealing element, such that the relevant portion of the access, particularly the area surrounding the internal tubing section, is flushed by the sterilizing solution.

[0009] The access system according to the invention is characterized by having a measuring electrode and at least one mating electrode disposed within a housing, such that the measuring electrode interacts with the mating electrode via a cavity. The measuring electrode allows for the coupling input or feed of electrical signals, enabling the evaluation of the current flowing between the measuring electrode and the mating electrode or the voltage applied between them. In this context, the evaluation of current and voltage is also understood as the measurement of (complex) resistance (impedance or reactance measurement). Based on the evaluation of current or voltage (complex resistance), it is possible to infer the presence of liquid or moisture in the cavity, and / or the presence of a specific liquid in the cavity, i.e., to distinguish one liquid from another.

[0010] If the presence of liquid in the cavity is inferred during disinfection of the access system, then the cavity can be considered to be at least partially filled with disinfectant. To monitor whether the cavity is completely filled with disinfectant liquid or to identify only partial filling (fill level), multiple paired electrodes can be provided, each paired electrode being associated with a specific region or segment of the cavity.

[0011] After disinfecting the access system, it is possible to check whether moisture remains in the cavity, that is, to check whether moisture is still present in the port, which forms a conductive connection between the measuring electrode and the mating electrode. It is assumed here that a dry port is generally free of pathogens, as it has been proven in practice that most pathogens bind with moisture.

[0012] In a preferred embodiment, the access system includes a connector that can be inserted into an opening to extract or deliver medical fluids. The connector has a tubing section extending into a cavity that can be fluid-tightly connected to a tubing section inside a housing, wherein the connection between the tubing section of the housing and the tubing section of the connector is located within the cavity.

[0013] During operation, the sealing of the connected system can be checked. If liquid is found in a cavity that is otherwise dry, it can be inferred that there is a leak at the connection point located in the cavity between the piping section of the housing and the piping section of the connector.

[0014] Another preferred embodiment proposes that the measuring electrode is a pin electrically insulated from the housing, the pin extending into the cavity. The pin may have electrical terminals on the housing side.

[0015] In a particularly preferred embodiment, the mating electrode is formed from at least a portion of the internal conduit section. This embodiment is advantageous for identifying liquids, especially substitutes, that may overflow at the connection between the conduit section of the housing and the conduit section of the connector. In this embodiment, at least a portion of the internal conduit section can be made of a conductive material, or at least a portion of the outer wall of the internal conduit section can be covered with a coating made of a conductive material.

[0016] In another particularly preferred embodiment, at least one mating electrode is formed by at least a portion of the external conduit section. This embodiment is advantageous if it is necessary to identify whether the cavity is filled with a disinfectant solution. In this embodiment, at least a portion of the external conduit section can be made of a conductive material, or at least a portion of the inner wall of the external conduit section can be coated with a conductive material. Depending on the degree to which the disinfectant solution fills the cavity, different resistances are generated between the measuring electrode and the mating electrode. The more the cavity is filled, the more current paths are formed, resulting in a decrease in resistance. If multiple mating electrodes are formed on the external conduit section, the mating electrodes can be configured such that specific conductive paths are formed to each mating electrode according to the filling level. Both of these can be monitored by corresponding evaluation of the signal, for example, by deviation from a reference value.

[0017] The access system can also have these two implementations, enabling the detection of one or more current paths between the measuring electrodes and internal and external conduit sections.

[0018] The monitoring system according to the invention, including the access system according to the invention, comprises: means for generating electrical signals, the means being electrically connected to a measuring electrode and at least one paired electrode; and an evaluation and calculation means configured to evaluate the current flowing between the measuring electrode and at least one paired electrode or to evaluate the voltage applied between the measuring electrode and at least one paired electrode.

[0019] The evaluation and calculation device can be configured to evaluate the current flowing between the measuring electrode and at least one paired electrode, or to evaluate the voltage applied between the measuring electrode and at least one paired electrode, to infer the presence of liquid or moisture in the cavity; or the evaluation and calculation device can be configured to identify the presence of a specific liquid in the cavity. Known evaluation methods can be used to determine the state of the access system.

[0020] The evaluation and calculation device can be configured to generate a control or notification signal if the presence of liquid or moisture in the cavity is inferred, and / or if the presence of liquid or moisture in the cavity is not inferred. The control or notification signal can, for example, intervene in the machine control of the medical device, such as preventing further treatment or issuing an alarm. The display can also prompt the operator to perform disinfection.

[0021] If the grounding of the mating electrodes is incorrect, especially if the grounding is interrupted, an increased leakage current may occur. Therefore, the device for generating the electrical signal is preferably configured such that the electrical signal is generated in successive time intervals. Because the measurement signal is applied for only a short time, the average current generated is smaller compared to that under continuous application.

[0022] For safety reasons, a coupling capacitor can also be installed between the evaluation and calculation device and the measurement electrode.

[0023] Another preferred embodiment proposes that the device for generating electrical signals has a frequency generator for generating alternating voltage or alternating current signals.

[0024] The evaluation and calculation device is equipped with means for rectifying the AC voltage signal, wherein the evaluation and calculation device is configured such that the rectified AC voltage signal (DC voltage) is compared with a reference value. If the rectified AC voltage signal is less than the reference value, it can be inferred that liquid or moisture is present in the cavity. The fill level can be inferred based on the level of the DC voltage, i.e., based on resistance.

[0025] However, it is also feasible to evaluate unrectified AC voltage / current signals generated when excited with AC voltage via a conductive connection formed by liquid / moisture between the measuring electrode and the mating electrode, in order to identify specific liquids, such as substitutes. The method for evaluating the signal is prior art. See DE 10 2010 028 902 A1 for details. Attached Figure Description

[0026] In the following sections, embodiments of the present invention are described in detail with reference to the accompanying drawings.

[0027] The attached diagram shows:

[0028] Figure 1 A highly simplified schematic diagram of a hemodialysis device according to the present invention is shown, wherein the hemodialysis device has a monitoring system according to the present invention and an access system according to the present invention.

[0029] Figure 2A cross-sectional view of an embodiment of the access system according to the present invention is shown.

[0030] Figure 3 An embodiment of the monitoring system according to the present invention is shown.

[0031] Figure 4 An equivalent circuit diagram is shown to illustrate the flow of current.

[0032] Figure 5 The time-varying curve of the AC voltage signal is shown.

[0033] Figure 6 This shows the frequency-dependent attenuation of the AC voltage signal, and

[0034] Figure 7 An embodiment of the evaluation and calculation apparatus for a monitoring system is shown. Detailed Implementation

[0035] Figure 1 As an example of medical device 1, a highly simplified schematic diagram illustrates an external blood therapy device having a monitoring system 2 for monitoring access to the medical device.

[0036] Current extracorporeal blood therapy devices are dual dialysis filtration devices, which have a dialyzer 3, which is divided by a semipermeable membrane 4 into a blood chamber 5 through which blood flows and a dialysate chamber 6 through which dialysate flows. The blood chamber 5 is part of the extracorporeal blood circuit I, while the dialysate chamber 4 is part of the dialysate system II of the dual dialysis filtration device.

[0037] The extracorporeal blood circuit I includes an arterial blood line 7 leading to the inlet 5a of the blood chamber 5 and a venous blood line 8 exiting from the outlet 5b of the blood chamber 5 of the dialyzer 3. The patient's blood is transported through the blood chamber 5 of the dialyzer 1 by means of an arterial blood pump 9 located at the arterial blood line 7. The blood lines 7 and 8 and the dialyzer 3 form a disposable device intended for single use, which is inserted into the dialysis apparatus for dialysis treatment.

[0038] Fresh dialysate is supplied in dialysate source 10. Dialysissate delivery line 11 leads from dialysate source 10 to inlet 6a of dialysate chamber 6 of dialyzer 3. Dialysissate outlet line 12 leads from outlet 6b of dialysate chamber 6 to outlet 13. Dialysissate pump 14 is connected to dialysate outlet line 12.

[0039] During dialysis treatment, a replacement fluid (substitute) can be delivered to the extracorporeal blood circuit I via replacement tubing 15b. In the current embodiment, replacement tubing 15b is connected to a section of the arterial blood tubing 7. The substitute can be a liquid provided in a substitute source 16 and delivered using a substitute pump 17. The substitute source 16 can be a container filled with a prepared substitute. In one embodiment, the substitute can also be delivered to an extracorporeal blood therapy device ( Figure 1 (Not shown) is prepared by filtering dialysate from dialysate source 10 via a sterile filter.

[0040] The alternative tubing 15b is part of a disposable product designed for single use. To connect the alternative tubing 15b to the blood therapy device, in the blood therapy device 1... Figure 1 The access system P (port) is only implicitly shown at the housing 1A, and the access system is located at... Figure 1 The diagram is shown schematically only. A fluid connection 15a is specifically provided for connecting the alternative material source 16 to the access system P.

[0041] The access system P can be disinfected before or after dialysis treatment, or at specific time intervals, such as once daily. In this embodiment, a disinfectant solution for disinfecting the access system P is provided in a container 18, which can replace the alternative source 16. The disinfectant solution is connected to the access system P via a fluid connection 15a to perform disinfection. During disinfection, the access system P is flushed with the disinfectant solution by guiding it from the container 18 to the access system P and removing it again from there via an outflow or return line 19. The blood treatment device 1 has... Figure 1 The monitoring system 20 is shown only implicitly in the image. The monitoring system is used to monitor the status of the access system.

[0042] In the following text, refer to Figure 2 A detailed description of an embodiment of the access system P (port).

[0043] The access system P has a multi-piece housing 21, which is fixed to the housing 1A of the blood therapy device 1 for easy access by the operator. The housing 21 contains internal tubing sections 22 for transporting substitute liquids or disinfectant liquids. The internal tubing sections 22 are surrounded by external tubing sections 24 to form a cavity 23 for containing the disinfectant liquid. Figure 2 It tapers to the right from the center. For extraction of the substitute, the outer casing 21 has an opening 25, which can be used... Figure 2 The sealing element is not shown. At the outer end of the internal piping section 22, there is a fluid connection 15a for guiding to the alternative source 16 or the sterile liquid container 18. Figure 1Interface 26.

[0044] To extract the replacement, the fitting connector 27 can be inserted into the opening 25. The connector 27 has an internal tubing section 28A extending into the cavity, which, when connected, is fluid-tightly connected to an internal tubing section 22 of the housing 21. The internal tubing section 28A is surrounded by a contact protection portion 28B. The opening formed by the internal tubing section 28A and the opening formed by the contact protection portion 28B are not in the same plane but are spaced apart, making it difficult or impossible to access the internal tubing section 28A of the connector 27. The connection portion 29 between the tubing section 22 of the housing and the tubing section 28A of the connector 27 is approximately located at the center of the cavity 23.

[0045] The disinfectant flows into cavity 23 via interface 26, which is connected to disinfectant container 18. The disinfectant flows out via channel 38b, which is connected to outflow or return pipe 19. Figure 1 ) connection. The disinfectant flowing out or squeezed out from cavity 23 can be placed in another container ( Figure 1 (Not shown in the image) Collected and subsequently removed, or discarded via an outlet.

[0046] To better remove the disinfectant from cavity 23, it is possible to introduce sterile air into the cavity via opening 38A. In this case, the sterile air is compressed, for example, by a compressor, and introduced into cavity 23. This compressed air can force any liquid present out of the cavity, for example, through opening 38B.

[0047] The access system P has a measuring electrode 30. In the current embodiment, the measuring electrode 30 is a pin that is electrically insulated relative to the housing 21. The pin-shaped measuring electrode 30 is located in a housing 31 made of an insulating material (e.g., PEEK), which is inserted into the housing 21. One end of the pin-shaped measuring electrode 30 extends into a cavity 23, while the other end extends out of the housing 21 to connect to electrical wiring.

[0048] The measuring electrode 30 is configured such that it interacts with at least one mating electrode 31, 32 via the cavity 23. At least a portion of the internal conduit section 22 functions as a first internal mating electrode 31, while at least a portion of the external conduit section 24 functions as a second external mating electrode 32. For this purpose, at least a portion of the internal conduit section 22 can be made of a conductive material, or at least a portion of the outer wall of the internal conduit section 22 can be provided with a coating 22A made of a conductive material. Correspondingly, at least a portion of the external conduit section 24 can be made of a conductive material, or at least a portion of the inner wall of the external conduit section 24 can be provided with a coating 24A made of a conductive material. In the current embodiment, the outer wall of the internal conduit section 22 is provided with a coating 22A, and the inner wall of the external conduit section 24 is provided with a coating 24A made of a conductive material.

[0049] The monitoring system 2 has a device 33 for generating electrical signals and an evaluation and calculation device 34, which in Figure 3 The connection system P and patient entrance 35 are schematically shown together. The internal piping section 22 and external piping section 24 of the connection system P are shown in... Figure 3 It is only implicitly shown in the text.

[0050] The device 33 for generating electrical signals includes a controllable frequency generator 33A, which generates an AC signal V having a preset frequency. ac For example, a sinusoidal signal with a frequency of 20 kHz. The frequency generator 33A can be controlled by a control device (CPU1). The generation of AC voltage can be achieved, for example, using a VCO (voltage controlled oscillator) or a programmable signal generator. For example, CPU1 can be configured as a programmable microcontroller.

[0051] The device 33 for generating electrical signals and the evaluation and calculation device 34 are connected to the measuring electrode 30 via an electrical connection line 35. A first switch 36 is provided to interrupt the electrical connection; this first switch can be opened or closed by a control signal en_meas from the second control device (CPU2). Additionally, a reference resistor R is provided. Ref When the second switch 37 is closed, the reference resistor connects the connection line 35 to ground. The second switch 37 can be opened or closed using the control signal `set_ref` from CPU2. Reference resistor R Ref Used for circuit function checks, which will still be described below.

[0052] For safety reasons, a coupling capacitor C is provided in the connection line 35, which can be configured as a Y-type capacitor. The Y-type capacitor provides high dielectric strength and reliably prevents capacitor breakdown, thus preventing dangerous voltage on the measuring electrodes.

[0053] According to the present invention, an electrical signal is applied to the measuring electrode 30. This electrical signal can be any voltage with an arbitrary voltage change curve, especially an alternating current voltage. If a conductive path is established between the measuring electrode 30 and the mating electrodes 31, 32 due to liquid residue, then the current flow in the current path between the measuring electrode and the mating electrode, or the voltage drop across the resistance generated between the measuring electrode and the mating electrode, can be measured.

[0054] To prevent leakage current, the conduit section 22 (or 22A) of at least one mating electrode 31 is grounded. Figure 3 As shown in [the diagram]. If multiple paired electrodes are used, for example in [the diagram]... Figure 2 As shown in (24 or 24A), the electrode is also grounded. In the event of improper grounding or grounding interruption (which is in Figure 3 As shown in the diagram, a relatively high leakage current may occur, which could endanger patient P. This situation must be avoided in all circumstances.

[0055] During dialysis treatment, a substitute containing conductive ions flows in the fluid connection 15a and the substitute tubing 15b, establishing a direct conductive flow connection with the patient's vascular system. In patients with a central venous catheter as an entry point into their vascular system, such as during acute dialysis, the catheter is placed close to the heart to ensure a sufficiently high blood flow in the extracorporeal blood circuit. In particular, in these patients, high leakage currents that could occur via capacitive coupling between the dialysis device and the fluid pathway within the patient's body must be avoided in all situations.

[0056] exist Figure 3 In the event of an interruption in the grounding connection of the mating electrode 31 as indicated, an increased leakage current may occur. If the connection points 29 of the internal housing-side piping sections and the internal connector-side piping sections 22, 24 are not sealed, a conductive liquid connection may occur between the measuring electrode 30 and the patient's vascular system, resulting in a current ip. The greater this current, the worse the grounding connection of the mating electrode.

[0057] Figure 4 The electrical equivalent circuit diagram is shown to illustrate this relationship. The total current i is limited by the internal resistance Ri of the source and the individual resistors (impedances) Z connected in series. scl +Z gnd and Z sc2 +Zsub +Z p Parallel circuit. In Figure 4 In the current example, R i From R fb ( Figure 7 The output resistor (not shown) of operational amplifier OP1 at the input of evaluation and calculation device 34 is generated, which will still be described in detail below. The coupling capacitor C is ignored here or its size is determined to have no relevant effect. scl It is the impedance generated at the conductive bridging junction between the measuring electrode and the mating electrode. Z gnd This is the impedance generated by the electrical connection between the mating electrodes and the protective conductor PE, which can be considered a pure ohmic cable connection. sc2 The impedance generated by a conductive bridging portion between the measuring electrode 30 and a possible unsealed portion in the port, for example at the connection point 29 of the conduit section on the inner housing side or the conduit section on the connector side. sub It is the impedance of the conductive liquid connection within the substitute conduit, which is related to the length and diameter of the substitute conduit 15b (the flexible conduit) and the ion content of the substitute. p This is the impedance generated between the overflow point of the substitute in the patient's vascular system and the patient's grounding point, which is related to, for example, the patient's position and size or the patient's clothing. For example, the patient might be holding a grounded metal object, etc. The above variables can be complex variables.

[0058] Current i p And especially its magnitude is crucial in determining the harm to the patient. If the grounding connection Z gnd It is defective, that is, if Figure 4 If the current path on the left is interrupted, then current i no longer branches into two paths, but flows only through the path on the right and thus through the patient. It must be ensured that current i p The value should not exceed 50 μA (effective) to eliminate health hazards even in fault conditions, i.e., when the grounding connection of the mating electrodes is interrupted. According to the invention, increased leakage current can be prevented by measures that can be applied individually or in combination.

[0059] Used to generate excitation voltage V ac The device 33 can be configured such that the excitation voltage V ac The value is limited to ensure that no leakage current greater than 50 μA flows even under fault conditions.

[0060] In addition, it is used to generate the excitation voltage V ac The device 33 can be configured to perform pulsed measurements. Excitation voltage V acIt is only loaded for a short period of time, then cut off, so that it can be reloaded periodically. This produces a smaller current on average compared to when the excitation voltage is continuously applied.

[0061] Figure 5 The sinusoidal excitation voltage V with a frequency of 20kHz is shown. ac The time-varying curve of the excitation voltage V. ac In time interval T on To apply the AC voltage, CPU1 generates a control signal en_meas, causing the first switch 36 to close.

[0062] Effective leakage current l peff Calculate using the following formula.

[0063]

[0064] Time than T on / T total It is pre-set to make signal evaluation feasible, to ensure that security is not compromised by excessive "pauses," and to effectively control leakage current I. peff Keep it below the limit value.

[0065] In addition, it is used to generate the excitation voltage V ac The device 33 can be configured such that the preset excitation voltage V ac The lowest frequency. Figure 6 As shown, the current path on the right ( Figure 4 The impedance generated by the excitation frequency increases with increasing frequency, and this impedance is decisive for the level of leakage current. Therefore, the signal attenuation D also increases with increasing frequency f. The excitation frequency and boundary conditions... Figure 6 The attenuation performance shown is selected accordingly so that even in fault conditions, the leakage current limit, such as 20 kHz, will not be exceeded.

[0066] The evaluation and calculation device 34 has circuitry for measuring and processing measurement signals. Figure 7 An embodiment of the circuit is shown, which includes three stages A1, A2, and A3, each having operational amplifiers OPI, OP2, and OP3.

[0067] The first stage, A1, acts as a feedback resistor R. fb The buffer is working. The electrical signal V generated by device 33... ac An AC voltage is applied to the positive input terminal of OP1. A measuring electrode 30 is connected to the negative input terminal of OP1 via a coupling capacitor C. Impedance Z sc(Short circuit) refers to a conductive bridging point between the measuring electrode 30 and the mating electrodes 31, 32 caused by liquid or moisture, which in this example is located at the reference potential PE, i.e., protective ground. This generates a characteristic current i. sc The liquid or moisture to be detected is usually not a pure ohmic resistance, but a mixture of ohmic and reactive impedances (capacitive or inductive). Therefore, the aforementioned variables can be complex variables. Thus, relative to the AC voltage V... ac In terms of current i sc Typically, it involves a phase shift. In one implementation, this can be used not only to detect the presence of liquid or moisture in the port, but also to draw conclusions about the type of liquid. For example, blood has a characteristic complex resistance, which differs from, for example, that of water.

[0068] If there is no conductive bridging portion between the measuring electrode 30 and the mating electrodes 31 and 32, then there is no current i. sc The current flows through. In this case, the flow rate at the - input terminal of the OPI is different from that at the + input terminal due to the feedback resistor R. fb Apply the same voltage, i.e., V ac Because no current flows through R. fb (The input resistance of AI can be considered very close to infinity), therefore OP1 = V. ac The output voltage.

[0069] However, if there is an electric current i due to liquid or moisture sc Flow, then R fb and Z sc A voltage divider is formed from the output of OPI to the PE reference potential (the effects of coupling capacitor C1 and the measurement electrodes are negligible within the operating frequency range). Therefore, the voltage at the -input terminal of OPI will decrease, but OP1 will remain constant as it operates via R... fb The feedback differential amplifier's characteristics boost the output voltage to a level that ensures the + and - input terminals of the OPI have the same voltage. Therefore, a Vi is generated at the output of the OPI. ac and i sc *Z sc The sum of voltages. This voltage, or the instantaneous characteristic of the voltage, characterizes the moisture present in the port, which establishes a conductive connection between the measuring electrode and the mating electrode. In stage A2, this voltage is rectified and averaged or smoothed, and in stage A3, the measured voltage is amplified. The rectifier and amplifier circuits are prior art. Therefore, a voltage V is generated. adc The voltage can be digitized using an analog-to-digital converter (not shown).

[0070] For example, it can include a controller CPU1 ( Figure 3 The evaluation and calculation device 34 is configured to evaluate the measurement signal using the computational operations described below in order to identify whether there is liquid or moisture in the cavity and / or what kind of liquid is present in the cavity. For this purpose, algorithms known to those skilled in the art can be used. If it is deduced that there is liquid or moisture in the cavity 23, then the evaluation and calculation device generates a control or notification signal.

[0071] Figures 8A to 8D The time-varying curve of the signal is shown. CPU1 generates the signal en_meas, which causes the first switch 36 ( Figure 3 )closure( Figure 8A At this point in time, an excitation voltage V is generated. ac For example, AC voltage with a frequency of 20kHz ( Figure 8B ). Figure 8C and Figure 8D The signals in the table represent the generated voltage Ana_in, which is evaluated by CPU2.

[0072] Figure 8C The following situation is shown: the port is dry (no CD detection), and Figure 8D The following situation is illustrated: Moisture has created a conductive connection between the measuring electrode and the mating electrode (CD detection). In the second case, the resulting voltage Ana_in is higher, which correspondingly allows for a connection with the reference value V. Ref The comparison is used for detection. In the current example, an AD conversion is performed on the measured voltage, and the voltage Ana_in is compared with the reference value V in CPU1 (the controller). Ref Comparison. However, it is also possible to use a simple (analog) comparator to evaluate the generated voltage Ana_in. If no excitation signal is applied and the measuring electrode 30 is not electrically connected to the circuit, then no voltage can be measured, which can also be checked by the circuit.

[0073] The first switch 36, controlled by the en_meas signal, is preferably positioned where an excitation voltage V should not be applied to the measuring electrode. ac The circuit is disconnected during the time interval. This isolates the measuring electrode 30 from the circuit, thus preventing unwanted leakage current.

[0074] After interrupting the current path to the coupling capacitor C by opening the first switch 36 and connecting the reference resistor R by closing the second switch 37. ref Afterwards (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, then an error exists. Figure 8C and Figure 8D The reference values ​​V for the upper and lower limits are shown in the figure.Ren V Ref2 For example, it can check whether the voltage is within the upper and lower reference values ​​(V). Ren V Ref2 between.

[0075] Based on the level of voltage Ana_in or voltage-related electrical variables, it is also possible to determine whether and to what extent the cavity is filled with liquid. This is particularly useful for inspecting the sterilization process.

[0076] The internal conduit section 22 or the external conduit section 24 can function as mating electrodes 31, 32. To check the fill level, at least a portion of the external conduit section 24 can alternatively or additionally be configured as the mating electrode 32. For example, a specific area of ​​the inner wall of the external conduit section 24 can be provided with a conductive coating 24A, forming multiple current paths from the measuring electrode to each area. Thus, different resistances are generated depending on the fill level of the cavity by the disinfectant liquid, where as the fill level increases, other current paths are formed, causing the resistance to decrease. This can be detected using the evaluation and calculation device 34. If multiple mating electrodes are provided, the evaluation and calculation device 34 can also be configured to evaluate multiple measurement signals. Depending on the fill level, a voltage or current value is generated for each mating electrode, which can be compared with a reference value characterizing the corresponding fill level.

[0077] In the above embodiment, the signal Ana_in, which is essentially rectified, is evaluated, thereby losing phase shift information between the measurement and excitation signals. However, it is also possible to evaluate an unrectified AC voltage / AC current signal. That is, if not only is a single excitation frequency used for measurement, but this frequency is changed (frequency scanning), then characteristic change curves are generated, which can be converted, for example, into impedance curves (a magnitude of impedance related to frequency). For blood, for example, due to the structure (cells in plasma), specific current paths and corresponding impedances are generated according to the measurement frequency. In this regard, see DE 102010 028 902 A1 for details and in particular its Figures 1 to 4 And the accompanying drawings. That is, using the method known from DE 10 2010 028 902 A1, the type of liquid involved can be determined by using the monitoring system 2 according to the invention. Dialysis fluids or alternatives have different characteristic impedance change curves due to their composition (cell-free), and can also be distinguished from each other, for example, by ion density, i.e., the density of free charge carriers.

Claims

1. An access system for a medical device, the access system having a housing (21) in which an internal tubing section (22) for transporting medical fluids is formed, the internal tubing section being surrounded by an external tubing section (24) to form a cavity (23) for containing a disinfectant fluid, wherein the housing (21) has an opening that can be closed by a sealing element. Its features are, A measuring electrode (30) and at least one mating electrode (31, 32) are disposed in the housing (21) such that the measuring electrode (30) interacts with the at least one mating electrode (31, 32) via the cavity (23). The evaluation and calculation device (34) is configured to evaluate the current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or to evaluate the voltage between the measuring electrode (30) and the at least one paired electrode (31, 32) to infer whether there is liquid or moisture in the cavity (23).

2. The access system according to claim 1, characterized in that, The measuring electrode (30) is an electrically insulated pin relative to the housing (21) that extends into the cavity (23).

3. The access system according to claim 1, characterized in that, The at least one paired electrode (31, 32) is formed by at least a portion of the internal conduit section (22).

4. The access system according to claim 3, characterized in that, At least a portion of the internal pipe section (22) is made of a conductive material, or at least a portion of the outer wall of the internal pipe section (22) is provided with a coating (22A) 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 paired electrode (31, 32) is formed by at least a portion of the external conduit section (24).

6. The access system according to claim 5, characterized in that, At least a portion of the external pipe section (24) is made of a conductive material, or at least a portion of the inner wall of the external pipe section (24) is provided with a coating (24A) made of a conductive material.

7. The access system according to any one of claims 1 to 4, characterized in that, The access system has a connector (27) that can be inserted into the opening (25), the connector having a conduit section (28A) extending into the cavity (23), the conduit section being fluid-tightly connected to a conduit section (22) inside the housing (21), wherein the connection portion (29) between the conduit section (22) inside the housing (21) and the conduit section (28A) of the connector (27) is located in the cavity (23).

8. A monitoring system, the monitoring system having an access system (1) according to any one of claims 1 to 7, characterized in that, The monitoring system has a device (33) for generating electrical signals, the device being electrically connected to a measuring electrode (30) and at least one paired electrode (31, 32), and the monitoring system has an evaluation and calculation device (34) configured to evaluate the current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or to evaluate the voltage located between the measuring electrode (30) and the at least one paired electrode (31, 32).

9. The monitoring system according to claim 8, characterized in that, The evaluation and calculation device (34) is configured to evaluate the current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or to evaluate the voltage between the measuring electrode (30) and the at least one paired electrode (31, 32) to infer whether there is liquid or moisture in the cavity (23).

10. The monitoring system according to claim 9, characterized in that, The evaluation and calculation device (34) is configured to generate a control or notification signal when it is inferred that liquid or moisture is present in the cavity (23), and / or when it is not inferred that liquid or moisture is present in the cavity (23).

11. The monitoring system according to any one of claims 8 to 10, characterized in that, The evaluation and calculation device (34) is configured to evaluate the current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or to evaluate the voltage between the measuring electrode (30) and the at least one paired electrode (31, 32) to infer whether a specific liquid is present in the cavity (23).

12. The monitoring system according to any one of claims 8 to 10, characterized in that, The means (33) for generating electrical signals is configured to generate electrical signals in successive time intervals.

13. The monitoring system according to any one of claims 8 to 10, characterized in that, The device (33) for generating electrical signals has a frequency generator (33A) for generating AC voltage or AC current signals.

14. The monitoring system according to claim 13, characterized in that, The evaluation and calculation device (34) has a means (A2) for rectifying an AC voltage signal, wherein the evaluation and calculation device (34) is configured to compare the rectified AC voltage signal with a reference value, wherein when the rectified AC voltage signal deviates from the reference value, it is inferred that there is liquid or moisture in the cavity (23).

15. A medical treatment device having a monitoring system (2) according to any one of claims 8 to 14.

16. The medical treatment device according to claim 15, characterized in that, The medical treatment device is a blood therapy device with an external blood circuit, the blood therapy device having a means for providing a substitute, wherein an internal tubing section is fluidly connected to the means for providing the substitute.

17. A method for monitoring an access system for a medical device (1), the access system having a housing (21) in which an internal tubing section (22) for transporting medical fluids is formed, the internal tubing section being surrounded by an external tubing section (24) to form a cavity (23) for containing a disinfectant fluid, wherein the housing (21) has an opening (25) capable of being closed by a sealing element, characterized in that, The input electrical signal is coupled by means of a measuring electrode (30), which interacts with at least one paired electrode (31, 32) via the cavity (23), wherein the current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or the voltage between the measuring electrode and the at least one paired electrode is evaluated to infer whether there is liquid or moisture in the cavity (23).

18. The method according to claim 17, characterized in that, The measuring electrode (30) is an electrically insulated pin relative to the housing (21) that extends into the cavity (23).

19. The method according to claim 17 or 18, characterized in that, The at least one paired electrode (31, 32) is formed by at least a portion of the internal conduit section (22) and / or by at least a portion of the external conduit section (24).

20. The method according to claim 17 or 18, characterized in that, The electrical signals are coupled in successive time intervals.

21. The method according to claim 17 or 18, characterized in that, The input electrical signal is coupled via a coupling capacitor.

22. The method according to claim 17, characterized in that, The electrical signal is an AC voltage with a preset frequency, or the electrical signal is an AC voltage with a frequency that changes over time.

23. The method according to claim 17, characterized in that, The current flowing between the measuring electrode (30) and the at least one paired electrode (31, 32) or the voltage between the measuring electrode and the at least one paired electrode is evaluated to infer whether a specific liquid is present in the cavity (23).

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