Injection system

Abstract

The invention relates to an injection system (1) for injecting fluids into the body of a patient (10), the injection system comprising: a) an injector (2) which has: a housing (21); a fluid container (22); a peristaltic pump (23) for conveying fluid from the fluid container (22) to the patient (10); and a flexible tube (24), connected to the patient (10), for transporting the fluid from the fluid container (22) to the patient (10); and b) an electrode (3), which can be attached to the patient (10), and an electrical conductor (4), which is electrically conductively connected to the electrode; c) wherein the pump (23) and the tube (24) form a first conductor path which conducts charges triboelectrically generated by the pump (23) and the tube (24) to the patient (10) via the tube (24); d) wherein the electrical conductor (4) is electrically conductively connected to the pump (23) or the housing (21) of the injector (2), and, together with the pump (23) or the housing (21), forms a second conductor path for removing the triboelectrically generated charges from the patient (10) to the pump (23) or the housing (21). The problem of avoiding interfering electrostatic charges or electrical impulses from the pump on electronics systems, and simultaneously preventing the patient from being exposed to high electrical currents, is solved by the invention by an injection system in which an impedance-generating component (5) for limiting the current removed by the second conductor path is arranged in the second conductor path.

Description

[0001] Injection system

[0002] The invention relates to an injection system for injecting fluids, e.g. contrast agents, into the human or animal body according to the preamble of claim 1, as well as a method for setting up the injection system.

[0003] In imaging procedures on the human or animal body for the purpose of medical diagnosis and the visualization of the structures and functions of body tissues and organs, such as magnetic resonance imaging (MRI) and computed tomography (CT), contrast agents are often administered to the body before or during the procedure to improve the contrast of the acquired images. By comparing images from the imaging procedure with and without contrast agents, the informative value of the acquired images can be improved and, for example, areas of inflammation or tumors characterized by a more intense white color can be better detected.

[0004] For the intravenous administration of contrast media, injectors are used. These transfer a contrast medium stored in a reservoir into a patient tube using a pump. The patient tube is connected to a cannula for intravenous administration of the contrast medium into the patient's body. A conveying device with a peristaltic pump is usually used to transfer the contrast medium from the reservoir to the patient tube. A transfer device in the form of a tube system or a cassette with fluid channels is inserted between the reservoir and the patient tube. This transfer device transfers the contrast medium from the reservoir into a pump tube, which is inserted into the peristaltic pump and connected to the patient tube. Another application for peristaltic pumps is in dialysis machines, where dialysate from the dialysate circuit, dialysis fluids and / or blood are pumped.

[0005] The pump tubing is inserted, for example, into a tubing bed of the peristaltic pump with an annular counterbearing and is alternately locally closed or occluded by pressure rollers acting radially outward toward the counterbearing. The movement of the rotating pressure rollers along the pump tubing successively shifts the closed area, thus enabling fluid delivery. One advantage of peristaltic pumps is the relatively good dosability of the fluid delivered in the pump tubing, e.g., the contrast agent. The fluid is transported from the reservoir into the patient tubing and does not come into contact with the pump, thus ensuring sterility.However, contact between the pressure rollers and the pump hose, combined with the flexion of the pump hose, and friction between the pressure rollers and the pump hose can lead to electrostatic charges on the pump hose. Pump hoses made of plastic or hoses with plastic surfaces are particularly prone to such triboelectrically generated charges.

[0006] In medical procedures, for example, during imaging procedures involving contrast medium administration, diagnostic devices with high-impedance measurement inputs, such as ECG devices, are used to monitor the patient's bodily functions and physiological parameters. The triboelectrically generated charges represent electrical interference pulses. These interference pulses cause the measurement results of the diagnostic devices to be disturbed or falsified and occur, for example, when using a peristaltic pump whenever the pressure rollers contact the pump tubing. Antistatic sprays are known to be inadequate approaches to eliminating such charges. For reasons of biocompatibility, tubing made of certain metal-containing materials is also unsuitable for reducing charges.Although some ECG devices can filter out these disturbances, and in particular the interference pulses, by using appropriate filters, this is complex and expensive and cannot be used in special applications, such as the testing of pacemaker signals, because such interference signals are very similar to the pacemaker signals to be measured.

[0007] Furthermore, it is known to reduce the interference pulse by creating a common potential equalization between the injector or the injector pump and the diagnostic device, e.g., through the use of a potential equalization conductor (POAG). In addition, the POAG protects the patient from mains carryover, in which, for example, a defective power cable lying around energizes the injector housing, resulting in a current flow via the patient to ground, e.g., a patient bed. This current flow is prevented by the POAG. Prior art US 10,265,025 B2 discloses a flexible cardiac catheter through which an electrically conductive fluid is pumped into a patient's heart by means of a peristaltic pump. While the fluid is being pumped, an ECG is performed on the patient to monitor the heart's electrical activity.An electrically conductive cable conducts charges induced in the fluid from catheter electrodes, for example, by short-circuiting them to a rotating element in the peristaltic pump. A triboelectric effect occurs in the cardiac catheter, particularly where a rotating contact of the pump compresses the pump tubing of the peristaltic pump, causing a triboelectric charge to build up in the fluid conveyed in the pump tubing, e.g., a saline solution. The charge flows through the tubing to the tip of the catheter and is conducted back to the pump via a cable from an ablation electrode in the tip of the catheter. The triboelectrically generated charges are intended to be disrupted, interrupted, or redirected to prevent them from flowing through the ECG electrodes in order to suppress noise in the ECG.The electrically conductive cable, which is preferably shielded, ultimately electrically short-circuits the patient with the fluid contained in the tube via a fluid connector on the tube. This virtually completely eliminates the pump-induced currents; the voltage difference of only 0.05 mV between a standard noise signal with an amplitude of 0.02 mV and the noise signal influenced by the pump-induced charges, with an amplitude of approximately 3.5 times that of 0.07 mV without a discharge, is completely eliminated by the use of the cable and the fluid connector. This requires the use of the best possible, lowest-impedance, and particularly lowest-resistance electrical connection along the entire conduction path from the ablation electrode via the cable to the fluid connector. The specialist will therefore keep the resistance and capacitance values ​​of these components as low as possible.

[0008] In view of the problems outlined above and based on the cited prior art, it is an object of the present invention to avoid or at least reduce the disruptive influences of electrostatic charges or electrical impulses from a peristaltic pump on electronic devices and at the same time to prevent the patient from being exposed to danger from high electrical currents.

[0009] This object is achieved with an injection system having the features of claim 1 and with a method having the features of claim 23. Preferred embodiments of the device and the method can be found in the dependent claims. In particular, the object is achieved in that a conductive connection is established between the patient and conductive parts of the pump or injector via a conduction path with an intermediate impedance. This allows the electrical charges generated by the peristaltic pump through frictional electricity to be conducted safely and safely from the patient to the injector or its pump, with the impedance limiting the current flow in the conduction path to limits that are safe for the patient. This makes it possible to avoid accidents that could occur, for example, due to improper operation of the electrical equipment or due to mains contamination, caused, for example, by a power failure.caused by a defective power cable.

[0010] The impedance is appropriately dimensioned to prevent dangerous currents while diverting the currents that interfere with ECG measurements, which are caused by the triboelectric effect in roller pumps. This eliminates the need for a potential equalization conductor (POAG). For this reason, the concept of the invention is more user-friendly and safer for the patient, as it no longer relies on the correct connection of the POAG, for example, to avoid the risk of grid contamination. Furthermore, the upgrade effort and costs for eliminating or mitigating triboelectrically generated voltages and their effects, such as interference pulses, are reduced.

[0011] The triboelectrically generated charges in the peristaltic pump arise from the fact that the pump tubing is first pressed against both the tubing bed and the pressure rollers by the pressure force of the pressure rollers. As the pump tubing continues to roll, the respective pressure roller lifts off the pump tubing. In the area where the pump tubing exits the peristaltic pump, the pressure rollers even lift completely off the pump tubing. However, during liftoff, the generated charges cannot be balanced quickly enough, so they remain as electrostatic charges on the respective surfaces of the pump tubing, the tubing bed, and the pressure rollers.As the rotor continues to rotate, driving the pressure rollers, the respective pressure roller comes into contact with the pump hose again in the area where the pump hose is inserted. This causes the electrostatic charges that have accumulated on the pressure roller to be transferred to the pump hose, thus causing a corresponding interference pulse. These charges lead to an electrostatic charge on the outer surface of the pump hose. The charge separation is caused by the triboelectric effect. Different materials have different electron affinities, and when certain materials, such as the pump hose and the pressure roller(s), are separated, the electrons cannot move freely enough. Therefore, no charge equalization takes place.

[0012] In addition to the generation of charges when the pressure roller comes into contact with the pump hose, electrostatic charges can also build up between the pump hose and the hose bed. When the pressure roller lifts off the corresponding section of hose as the rotor continues to rotate, the elastic restoring forces within the pump hose cause it to return to its basic round shape, so that the pump hose is no longer in surface contact with its hose bed, but only in line contact. This causes the pump hose to partially lift off the hose bed, which can lead to the creation of electrostatic charges. The triboelectrically generated charges on the surface of the pump hose are passed on to the patient hose connected to the pump hose and can thus flow to the patient.

[0013] Due to the periodicity of the peristaltic pump's pumping motion, which is generated by the rotation of the pressure rollers at a predetermined rotational frequency, the triboelectric currents generated by the pump have a frequency that depends on the pump's rotational frequency and the number of pressure rollers. The frequency of the currents generated by the pump is the product of the number of pressure rollers and the pump's rotational frequency, which is determined by the rotational frequency of a rotor on which the pressure rollers are arranged. Depending on the pump's rotational frequency and the number of pressure rollers, this frequency of the triboelectric currents generated by the pump can range from 0.5 Hz to 20 Hz.

[0014] According to one aspect of the invention, an injection system for injecting or infusing fluids into a patient's body is provided, wherein the injection system comprises an injector comprising a housing, a fluid container, a peristaltic pump for conveying the fluid from the fluid container to the patient, and a flexible tube connected to the patient for transporting the fluid. Furthermore, the injection system comprises an electrode attachable to the patient and an electrical line electrically connected to the electrode, which is electrically connected to the pump or the housing of the injector. The pump and the tube form a first conduction path that conducts triboelectrically generated charges via the tube to the patient.The electrical line and either the pump or the injector housing form a second conduction path that conducts the triboelectrically generated charges from the patient to the pump or housing. According to the invention, an impedance-generating component is located in the second conduction path to limit the current discharged through the second conduction path. The impedance-generating component is also referred to herein as the "impedance."

[0015] A further aspect of the present invention is directed to the special design of the impedance-generating component. The impedance-generating component preferably comprises a resistor for limiting alternating current and / or a capacitor for limiting direct current. In a preferred embodiment, the resistor limits the alternating current to a maximum of 500 pA and / or the capacitor limits the direct current to a maximum of 50 pA. The specified values ​​meet the requirements of the IEC 60601-1 standard for medical electrical equipment, which can prevent serious harm to the patient.

[0016] A further aspect of the present invention is that the impedance-generating component is preferably not in direct contact with the fluid. This is advantageous because triboelectrically generated charges do not enter the patient's body via the fluid, but are dissipated via the patient, particularly the contact point of the electrode on the patient (usually the patient's skin). This is intended to prevent the fluid itself from becoming a conductor and distributor of the triboelectrically generated charges.

[0017] In a further aspect of the present invention, the impedance-generating component is integrated either into the electrical line or into the injector. If the impedance-generating component is integrated into the injector, this has the advantage that the electrode and the electrical line, as comparatively simple and inexpensive components, can be quickly replaced in the event of damage, since they are correspondingly quickly available and easy to replace. If, on the other hand, the impedance-generating component is integrated into the electrical line, this has the advantage that a so-called ECG kit can be used, which consists of the electrode, the electrical line, and the impedance-generating component. Thus, for example, known ECG kits for an injector can be retrofitted with the impedance-generating component.

[0018] In a further aspect of the present invention, the electrical line is electrically connected to the injector housing via a connection socket in the housing. Advantageously, the connection socket in the housing is selected such that contact between the electrical charges or current in the electrical line and any liquid in the vicinity of the patient and / or the injector can be avoided. Thus, short circuits due to contact between the electrical line and the liquid can be ruled out. This further increases the safety of the patient, as well as that of the injector, against injury.

[0019] In a further aspect of the present invention, the electrical line is electrically connected to the housing downstream or upstream of the pump. Advantageously, this takes into account the fact that, depending on the material selected for the pump, hose, and hose bed, a different electron affinity is caused by the different materials of these parts, which leads to triboelectric voltages. It is desirable for the electron affinity to be as low as possible. The location for returning the triboelectrically generated charges to the injector can be selected accordingly. Depending on the use of certain materials, it may be expedient to return the triboelectrically generated charges either downstream or upstream of the pump. Accordingly, the electrical line is electrically connected to the housing either downstream or upstream of the pump.

[0020] In a further aspect of the present invention, the electrical line is electrically connected to a frame or at least one rotating element (at least one pressure roller) of the peristaltic pump. As explained for the previous aspect, the location for returning the triboelectrically generated charges to the injector can be selected such that the electron affinity is as low as possible. It can be advantageous to return the triboelectrically generated charges directly to the pump, for example to a frame of the pump or to at least one rotating element of the pump. Since the charges arise from friction between the at least one rotating element of the pump (pressure roller) and the pump hose, it can be useful to return triboelectric charges that have already been generated and returned to their place of origin.This has the advantage that fewer components are exposed to the charges, consequently fewer materials contribute to the electron affinity and the electron affinity is therefore as low as possible.

[0021] In a further aspect of the invention, an injector for injecting or infusing fluids into a patient's body can be retrofitted with an electrical line incorporating an impedance-generating component for limiting the current discharged through this line. The electrical line with the integrated impedance component is electrically connected to the pump or the housing of the injector, so that the line, together with the pump or the housing, forms a second conduction path for discharging the triboelectrically generated charges from the patient to the pump or the housing. In this case, the line with the integrated impedance component is expediently located entirely outside the housing of the injector.

[0022] Preferably, the impedance-generating component of the injection system can have a high-pass filter function. This advantageously and easily keeps direct current or low-frequency current away from the patient, and also safely diverts the higher-frequency current components typically caused by triboelectrically generated charges, thereby reducing or completely preventing their interference with the detected useful signal, for example, an ECG signal.

[0023] The high-pass function can preferably be formed by passive electrical components, in particular resistors, capacitors, and / or inductors. The use of passive components has the advantage of a simple and cost-effective implementation of the high-pass function. It also eliminates the need for additional sensors. In a preferred, particularly cost-effective, and structurally simple embodiment, the impedance-generating component consists of a series circuit of at least one resistor and at least one capacitor.

[0024] Preferably, the core properties of one or more of the electrical components can be adjustable, for example the resistance value of a resistor, the capacitance of a capacitor or the inductance of a coil. This advantageously allows the characteristic properties of the high-pass filter to be subsequently adjusted and, if necessary, adapted on-site to specific environmental conditions, system designs or even the wear and aging of the components or parts of the system. If, for example, a different, new or differently long patient tube is used in a system, the triboelectric properties may change. The same applies to the replacement of or changes to the properties of the pump, for example a change in the pump speed. For example, potentiometers, trimming capacitors, tuning coils, etc. can be used for this purpose.

[0025] Furthermore, the high-pass function can preferably block the discharge of direct current or current with a frequency below a lower limit frequency of a current caused by the triboelectrically generated charges, typically periodic or quasi-periodic, via the second conduction path. This can ensure that no direct currents or low-frequency currents can affect the patient. In this case, the high-pass function can advantageously block currents with a frequency less than or equal to 5 Hz, preferably less than or equal to 1 Hz, and particularly preferably less than or equal to 0.2 Hz. Furthermore, the high-pass function can preferably allow currents with a frequency greater than or equal to 15 Hz, preferably greater than or equal to 10 Hz, and particularly preferably greater than or equal to 0.2 Hz to pass through.This ensures that the tribo-electric currents generated by the peristaltic pump, which typically lie in the frequency range of 0.5 to 20 Hz, are allowed to pass through.

[0026] Preferably, the impedance-generating component can further comprise a bandpass function that blocks the discharge of current with a frequency above an upper limit frequency of a current generated by the triboelectrically generated charges via the second conduction path. As a result, the high-pass function described above and below and defined in the claims, and in particular its low-frequency stopband, can be supplemented by a stopband for higher frequencies that lie above the typical and, in particular, the highest frequencies of the current generated by the triboelectrically generated charges.

[0027] Preferably, the second conduction path can comprise the electrical line and, in addition to the electrical line, the impedance-generating component. A conventional electrical line, such as that proposed, for example, in US Pat. No. 10,265,025 B2 for short-circuiting the patient with the fluid to be introduced, cannot therefore be understood as an impedance-generating component, because such lines should have the lowest possible impedance values, in particular resistance values, in order to be able to compensate for charge differences without hindrance. In contrast, the minimum value of an effective resistance of the impedance-generating component, in particular in the case of an ohmic resistor as a component of the impedance-generating component, can preferably be at least 200 kΩ, 220 kΩ, 240 kΩ, 242 kΩ, 264 kΩ, 440 kΩ, 460 kΩ, 480 kΩ, 484 kΩ, 506 kΩ, or 528 kΩ.Likewise, additionally or alternatively, a minimum value of a DC resistance of the impedance-generating component, in particular a capacitance, preferably a capacitor, as a component of the impedance-generating component, can preferably be at least 3.46 MQ, 3.81 MQ, 4.16 MQ, 4.19 MQ, 4.57 MQ, 7.62 MQ, 7.97 MQ, 8.31 MQ, 8.38 MQ, 8.76 MQ, and / or 9.15 MQ. Preferably, the minimum value of the effective resistance can be switchable between two or more of the specified values ​​and / or the minimum value of the DC resistance can be switchable between two or more of the specified values, so that it can be quickly adapted to changing or different conditions.

[0028] A further aspect of the present invention is a method for setting up the injection system according to the invention with the following steps:

[0029] - Connect the fluid container to the injector pump via the flexible hose,

[0030] - Attaching the tube to the patient,

[0031] - Attaching the electrode, which is electrically connected to the electrical line and the impedance-generating component, to the patient, and

[0032] - Establish an electrical connection between the electrical line and either the pump or the injector housing.

[0033] This procedure ensures that triboelectrically generated charges can be safely discharged from the patient. The pump should only be put into operation once the above steps have been completed, as the first and second conduction paths are then already established.

[0034] These and other advantages and features of the invention will become apparent from the embodiment described in more detail below with reference to the accompanying drawings. The drawings show:

[0035] Fig. 1: View of an injector for injecting a fluid into a patient; Fig. 2: Detailed view of a conduction path with an impedance-generating component;

[0036] Fig. 3: Impedance-frequency diagram for the course of the apparent resistance Rtotal of the

[0037] Impedance-generating component, the effective resistance of the ohmic resistor R of the impedance-generating component and the reactance Xc of the capacitor of the impedance-generating component.

[0038] Fig. 1 shows an injection system 1 having an injector 2 and an electrical line 4 with an electrode 3 and an impedance-generating component 5. The injector 2 comprises at least one receptacle 22 for a fluid container (not shown here), which is connected to an exchangeable cassette 22b via at least one supply tube 22a. In the exemplary embodiment in Figure 1, three receptacles 22 are provided, into each of which a fluid container can be inserted and connected to the cassette 22b via a supply tube 22a. Each fluid container contains a fluid to be injected (e.g., a contrast agent CM or a rinsing solution, e.g., NaCl), which flows into the cassette 22b via the respective supply tube 22a. The cassette 22b comprises a body with fluid channels formed therein, wherein an inlet channel is connected to a fluid container via a supply tube 22a.

[0039] A looped pump tube 24a is arranged on the underside of the cassette 22b and is connected to an output channel and an input channel of the cassette 22b. A connecting tube 24c is in turn connected to another output channel of the cassette 22b and leads via an analyzer 25 to a patient tube 24b, which is connected intravenously to the patient. The at least one supply tube 22a and the cassette 22b, as well as the tube system 24, which comprises the pump tube 24a, the connecting tube 24c, and the patient tube 24b, form a transfer device between the at least one fluid container and the patient 10, wherein the volume flows of the fluid are controlled in the cassette 22b.From the cassette 22b, the fluid to be injected flows into the pump tube 24a, from there back into the cassette 22b, and finally via the connecting tube 24c and the connected patient tube 24b into the patient's bloodstream. A peristaltic pump (hose pump or roller pump) 23 is provided to convey the fluid to be injected from the at least one fluid container through the corresponding fluid channel of the cassette 22b and the connected pump tube 24a into the connecting tube 24c and the patient tube 24b. This peristaltic pump 23 cyclically squeezes the pump tube 24a in a tube bed 23c of the pump 23, thereby conveying the fluid in the pump tube 24a via the connecting tube 24c into the patient tube 24b. In addition to the hose bed 23c, the pump further comprises a frame 23a and at least one rotating element, for example at least one pressure roller, 23b.

[0040] When the injector 2 is in operation and a patient is connected to the patient tube 24b, a triboelectric effect occurs in parts of the injection system 1, where the at least one roller 23b of the pump 23 compresses the tube 24, thereby pressing the tube 24 against the tube bed 23c as well as against the at least one roller 23b. As it continues to roll, the at least one roller 23b lifts off the pump tube 24a. However, during liftoff, the generated charges cannot be balanced quickly enough, so they remain as electrostatic charges on the respective surfaces of the pump tube 24a, the tube bed 23c, and the at least one pressure roller 23b.

[0041] In the area where the pump hose 24a is inserted, the at least one pressure roller 23b also comes into contact with the pump hose 24a again, resulting in the electrostatic charges that have accumulated on the at least one pressure roller 23b being transferred to the pump hose 24a and leading to an electrostatic charging of the outer surface of the pump hose 24a. These triboelectrically generated charges flow from the pump hose 24a via the patient hose 24b to the patient 10. Therefore, the pump 23 and the hose system 24 form a first conduction path that conducts the triboelectrically generated charges by the pump 23 and the hose 24 via the hose 24 to the patient 10.

[0042] The electrode 3 is applied to the patient 10 in an electrically conductive manner, e.g., adhered to the patient's skin with an electrically conductive paste, so that the patient is electrically connected to the injector 2, in particular the pump 23 or the housing 21 of the injector 2, via the electrical line 4. The electrical line 4 forms a second conduction path either with the pump 23 or with the housing 21, which conducts the triboelectrically generated charges from the patient 10 either to the pump 23 or to the housing 21. In particular, the triboelectrically generated charges can be conducted to the electrically conductive frame 23a or the at least one pressure roller 23b of the pump 23 or to an electrically conductive connection 21a of the housing 21.Thus, the tribo-electrically generated charges that have flowed onto the body of the patient 10 via the first conduction path can be guided back to the injector 2 via the electrode 3 and the second conduction path.

[0043] An impedance-generating component 5 is arranged in the second conduction path to limit the current discharged through the second conduction path. Alternatively, the impedance-generating component 5 can also be integrated into the injector. The impedance-generating component 5 has a resistor R for limiting alternating current and / or a capacitor C for limiting direct current. In a preferred embodiment, the resistor R limits the alternating current to a maximum of 500 pA and / or the capacitor C limits the direct current to a maximum of 50 pA. This ensures compliance with the maximum currents that may flow through the patient 10, as defined in the IEC 60601-1 standard.

[0044] For clarity, Fig. 2 shows a detailed view of the second conduction path with the impedance-generating component 5. In Fig. 2, the first conduction path from the pump 23 to the patient 10 is drawn in thick, and the second conduction path from the patient 10 via the impedance-generating component 5 to the connection 21a of the housing 21 of the injector 2 is drawn in thin.

[0045] To set up the injection system 1, the following steps are performed: connecting at least one fluid container to the pump 23 of the injector 2 via the hose system 24, attaching the patient hose 24b to the patient 10, attaching the electrode 3, which is electrically connected to the electrical line 4 and the impedance-generating component 5, to the patient 10, and establishing an electrical connection between the electrical line 4 and either the pump 23 or the housing 21 of the injector 2. Only after these process steps have been performed should the pump 23 be started, since the first conduction path and the second conduction path are then already established. This ensures that the triboelectrically generated charges can be dissipated.The injector system of the invention is not limited to the above components and features of the embodiment shown in the drawings and further advantageous embodiments, developments and modifications are within the scope of the claimed invention, which is defined by the claims.

[0046] As explained in detail in the description of the invention, the focus of the invention is to prevent the disruptive influence of electrostatic charges or electrical impulses from a peristaltic pump on electronic devices, as well as to ensure patient safety. This is achieved by using an impedance-generating component in a conduction path to divert these charges away from the patient and back to the injector. The impedance-generating component limits the currents through the conduction path to permissible limits, thereby reliably protecting the patient from excessive currents that could endanger the patient's health or even life.

[0047] Preferably, the impedance-generating component 5 can act as a high-pass filter, wherein in the present embodiment the capacitor C completely blocks any direct current that may occur up to a predetermined cut-off frequency or at least reduces it to a predetermined limit value, preferably max. 50 pA.

[0048] To achieve this condition, the capacitor C has a DC resistance of at least 8.00 MO at a capacitance value of 470 nF, for example, at a DC voltage of 400 V (assuming a rectified AC mains voltage of 264 V). Preferably, the capacitor C is suitable for operation at AC mains voltage, particularly between the outer conductor and protective earth, in order to efficiently serve as a protective barrier for the patient 10. The contribution of the resistor R to current limitation at DC voltage, however, is very small and negligible.

[0049] The resistor R of the impedance-generating component 5 limits the alternating current in a preferred embodiment to a maximum of 500 pA. This can be achieved, for example, if the value of the resistor R has a value of at least 530 kΩ at a maximum mains voltage of 264 V. In the present exemplary embodiment, a resistance value of 680 kΩ was used. The contribution of the capacitor C to current limitation at alternating voltage is, in contrast, very small and negligible, e.g. at 60 Hz mains alternating voltage and 470 nF capacitance of the capacitor C only around 5 kΩ. The cutoff frequency of the high pass filter, here the RC high pass filter, is fundamentally determined by the speed of the roller pump 23 and the number of its pressure rollers 23b and is fundamentally between 0.01 Hz and 20 Hz, specifically in the range between 0.1 Hz and 20 Hz and in particular at 1 Hz.Accordingly, the cutoff frequency of the high-pass filter is in the range between 0.01 Hz and 20 Hz, preferably between 0.2 and 10 Hz, and most preferably between 1 and 6 Hz, and in particular at 5 Hz.

[0050] The impedance-frequency diagram shown in Fig. 3 plots the impedance Rtotal of the impedance-generating component 5, i.e., its frequency-dependent resistance formed by the ohmic resistor R and the capacitor C, over a logarithmically represented frequency range from 0.01 Hz to 1000 Hz. Additionally, the reactance Xc of the capacitor C and the constant resistance of the resistor R are also plotted against frequency. The impedance Rtotal assumes values ​​such that an alternating current is limited to less than 500 pA at 264 V (240 V mains voltage + 10% safety margin and 60 Hz) and a direct current to less than 50 pA at 400 V DC.

[0051] As can be seen from Fig. 3, the proportion of the reactance Xc of the apparent resistance Rtotal decreases steeply, starting from very high values ​​at low frequencies, and then at higher frequencies approximates the curve of the purely ohmic effective resistance R. The desired high-ohmic value of the apparent resistance Rtotal of 8 MQ is already achieved here at frequencies below 0.02 Hz, so that pure direct current or very low-frequency currents are efficiently blocked and there is no danger to the patient 10. It can also be seen that at frequencies greater than 0.1 Hz the apparent resistance Rtotal quickly approximates the pure ohmic effective resistance R, whereby the periodic triboelectric currents generated by the pump 23 can be efficiently dissipated and do not negatively affect the useful signal, e.g. ECG signal.

[0052] Instead of the impedance-generating component 5 shown in Figs. 1 and 2 and described above, with a capacitor and resistor connected in series as a simple implementation of a first-order high-pass filter, the high-pass function can also be implemented in another way. For example, an impedance-generating component can be implemented as a second-order high-pass filter by connecting a capacitor, a resistor, and a coil in series. The high-pass function can also be implemented using a resistor and an inductor, in particular a coil. These purely passive implementations of the high-pass function have the advantage of being simple and cost-effective and, in particular, do not require additional sensors.

[0053] In a preferred embodiment, adjustable components can also be used in the passive circuits described above, for example potentiometers, trimming capacitors, tuning coils, etc. This allows the cutoff frequency of the high-pass filter to be set and readjusted on site, e.g., when environmental properties such as humidity or temperature change, resulting in an influence on the strength of the triboelectric charge, to which the properties of the impedance-generating component 5 can then be adapted.

[0054] The high-pass function can also be realized by active components or circuits, for example by an operational amplifier circuit.

[0055] Instead of a high-pass filter, a band-pass filter can also be used, the upper cut-off frequency of which is then chosen so that the dissipation of the typically occurring periodic tribo-electric currents is not blocked, while the permeability for signals with an even higher frequency is then reduced.

[0056] List of reference symbols:

[0057] 1 - Injection system

[0058] 2 - Injector

[0059] 21 - Housing

[0060] 21a - Connection

[0061] 22 - Recording

[0062] 22a - Supply hose

[0063] 22b - Cassette

[0064] 23 - Pump

[0065] 23 a - Frame

[0066] 23b - rotating element

[0067] 23c - Tube bed

[0068] 24 - Hose

[0069] 24a - Pump hose

[0070] 24b - Patient tube

[0071] 24c - Connection hose

[0072] 25 - Analyzer

[0073] 3 - Electrode

[0074] 4 - Electrical cable

[0075] 5 - Impedance-generating component

[0076] 10 - Patient

[0077] Rtotal - Apparent resistance of the impedance-generating component (series circuit

[0078] capacitor and resistor)

[0079] R - Effective resistance of the impedance-generating component

[0080] Xc - reactance capacitor of the impedance-generating component

Claims

Claims 1. An injection system (1) for injecting or infusing fluids into the body of a patient (10), comprising: a) an injector (2) with i) a housing (21), ii) a fluid container (22), iii) a peristaltic pump (23) suitable for conveying fluid from the fluid container (22) to the patient (10), and iv) a flexible tube (24) connected to the patient (10) and suitable for transporting the fluid from the fluid container (22) to the patient (10), and b) an electrode (3) attachable to the patient (10) and an electrical line (4) electrically connected to the electrode (3), c) wherein the pump (23) and the tube (24) form a first conduction path that conducts triboelectrically generated charges by the pump (23) and the tube (24) via the tube (24) to the patient (10),and d) wherein the electrical line (4) is electrically conductively connected to the pump (23) or the housing (21) of the injector (2) and forms a second conduction path with the pump (23) or the housing (21) for discharging the triboelectrically generated charges from the patient (10) to the pump (23) or the housing (21), e) characterized in that an impedance-generating component (5) for limiting the current discharged through the second conduction path is arranged in the second conduction path.

2. System according to claim 1, wherein the impedance-generating component (5) comprises a resistor for limiting alternating current and / or a capacitor for limiting direct current.

3. System according to claim 2, wherein the resistor (R) limits the alternating current to max. 500 pA.

4. System according to claim 2 or 3, wherein the capacitor (C) limits the direct current to max. 50 pA.

5. System according to one of the preceding claims, wherein the impedance-generating component (5) is not in direct contact with the fluid.

6. System according to one of the preceding claims, wherein the impedance-generating component (5) is integrated either into the electrical line (4) or into the injector (2).

7. System according to one of claims 1 to 6, wherein the electrical line (4) is electrically connected to the housing (21) of the injector (2) via a connection socket (21a).

8. System according to one of claims 1 to 7, wherein the electrical line (4) is electrically connected to the housing (21) downstream or upstream of the pump (23).

9. System according to one of claims 1 to 7, wherein the electrical line is electrically connected to a frame (23a) or at least one rotating element (23b) of the peristaltic pump (23).

10. System according to claim 9, wherein the at least one rotating element (23b) of the pump (23) builds up the tribo-electrically generated charges when rotating on the hose (24).

11. System according to one of the preceding claims, wherein the impedance-generating component (5) has a high-pass function.

12. System according to claim 11, wherein the high-pass function is formed by passive electrical components, in particular resistors (R), capacitors (C) and / or inductors, in particular a series circuit of at least one resistor (R) and at least one capacitor (C).

13. The system of claim 12, wherein the core properties of one or more of the electrical components are adjustable.

14. The system of any one of claims 11 to 13, wherein the high-pass function blocks the dissipation of direct current or current having a frequency below a lower cutoff frequency of a current caused by the triboelectrically generated charges via the second conduction path.

15. System according to one of claims 11 to 14, wherein the high-pass function blocks currents with a frequency less than or equal to 5 Hz, preferably less than or equal to 1 Hz and particularly preferably less than or equal to 0.2 Hz.

16. System according to one of claims 11 to 15, wherein the high-pass function passes currents with a frequency greater than or equal to 15 Hz, preferably greater than or equal to 10 Hz and particularly preferably greater than or equal to 0.2 Hz.

17. System according to one of the preceding claims, wherein the impedance-generating component (5) has a bandpass function which blocks the dissipation of current having a frequency which is above an upper limit frequency of a current caused by the tribo-electrically generated charges via the second conduction path.

18. System according to one of the preceding claims, wherein the second conduction path comprises the electrical line (4) and, in addition to the electrical line (4), the impedance-generating component (5).

19. System according to one of the preceding claims, wherein a minimum value of an effective resistance of the impedance-generating component, in particular of an ohmic resistance as a component of the impedance-generating component, is preferably at least 200 kQ, 220 kQ, 240 kQ, 242 kQ, 264 kQ, 440 kQ, 460 kQ, 480 kQ, 484 kQ, 506 kQ and / or 528 kQ.

20. System according to one of the preceding claims, wherein a minimum value of a DC resistance of the impedance-generating component, in particular a capacitance as a component of the impedance-generating component, is preferably at least 3.46 MO, 3.81 MQ, 4.16 MO, 4.19 MQ, 4.57 MQ, 7.62 MQ, 7.97 MO, 8.31 MQ, 8.38 MQ, 8.76 MQ and / or 9.15 MQ.

21. System according to claim 19 or 20, wherein the minimum value of the effective resistance is switchable between two or more of the specified values ​​and / or the minimum value of the DC resistance is switchable between two or more of the specified values.

22. A method for setting up the injection system (1) according to any one of the preceding claims, comprising the following steps: a) connecting a fluid container (22) of an injector (2) containing a fluid to a peristaltic pump (23) of the injector (2) via a flexible hose (24) of the injector (2); b) attaching the hose (24) to a patient (10); c) attaching an electrode (3) electrically connected to an electrical line (4) and an impedance-generating component (5) to the patient (10), and d) establishing an electrical connection between the electrical line (4) and the pump (23) or the housing (21) of the injector (2).

23. The method according to claim 22, wherein the electrical connection is formed with a connection socket (21a) in the housing (21) of the injector (2).

24. The method according to claim 22 or 23, wherein the electrical connection downstream or upstream of the pump (23) is formed electrically with the housing (21).

25. The method according to claim 22, wherein the electrical connection is formed with the frame (23a) or the rotating element (23b) of the peristaltic pump (23).

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