Infusion system, infusion filter for use in an infusion system of this type and method for operating an infusion system of this type

Abstract

The invention relates to an infusion system (10) having an infusion line (12), said infusion line (12) comprising an infusion filter (16) with a filter membrane (18), and a method for operating the infusion system. In the infusion system, a respective electrode (22) is arranged at opposite ends (20) of the filter membrane (18) in the flow direction of an infusion fluid (14), wherein the infusion system (10) comprises at least one measuring device (24) for detecting a current between the electrodes (22).

Description

[0001] Title: Infusion system, infusion filter for use in such an infusion system and method for operating such an infusion system

[0002] Description

[0003] The invention relates to an infusion system with a filter membrane and a method for operating the infusion system.

[0004] State of the art

[0005] Infusion systems for healthcare applications are known from the prior art, which include measuring devices for determining the flow rate of an infusion fluid. The measuring devices used are mostly based on calorimetric methods for measuring the

[0006] Flow rate. It is also known to derive information about the flow rate based on mechanical energy transfer via inline turbines. A disadvantage of the known systems is that they cannot provide accurate dynamic measurements over a large measuring range and / or are susceptible to environmental influences. Furthermore, the laminarity of the flow must be taken into account to obtain an accurate measurement result.

[0007] The present invention is based on the objective of providing an improved infusion system.

[0008] This problem is solved by an infusion system having the features of claim 1.

[0009] The infusion system comprises an infusion line, which in turn comprises an infusion filter with a filter membrane. The filter membrane is, for example, a cellulose or polysulfone membrane, which are used in infusion or dialysis systems. The invention provides that an electrode is arranged at each of the ends of the filter membrane opposite the end in the direction of flow. The infusion system further comprises a measuring device for detecting a current between the electrodes.

[0010] An infusion solution is electrically conductive due to electrolytic dissociation. The invention utilizes the zeta potential that builds up during operation of the infusion system at an interface between a surface, for example the electrode, and the liquid, for example the infusion solution. As the infusion solution flows through the infusion line, the current between the electrodes can now be measured.

[0011] The flow of the infusion solution itself can be caused, for example, by a hydrostatic pressure gradient, an active pumping device, or additional pressure. In particular, it may be intended that the flow of the infusion solution itself is not electrically induced.

[0012] Based on the recorded current, a conclusion can therefore be drawn about the flow rate of the infusion solution.

[0013] For example, the relative change in current can be used to monitor parenteral access, particularly the infusion system. The relative change in current can serve as a criterion for detecting an infusion, especially to identify and verify a bolus infusion.

[0014] In one advantageous embodiment, each electrode is formed by coating the edge regions at the respective end of the filter membrane with a conductive material. For example, conductive material can be deposited using a suitable deposition method. In this way, a flow measurement system can be realized that can be integrated inline into existing systems, such as disposable infusion systems, without major modifications.

[0015] The electrode can advantageously be formed across a cross-section of the filter membrane and / or across a cross-section of the infusion line. According to an advantageous embodiment, the infusion system comprises at least one measuring device for detecting a pressure difference across the filter membrane.

[0016] In an advantageous embodiment, the measuring device for detecting the pressure difference comprises a strain gauge-based pressure sensor. For example, a strain gauge is arranged on each side of the filter membrane in the infusion line, particularly at or near each end of the filter membrane.

[0017] According to an advantageous embodiment, the infusion system further comprises a computing device, wherein the computing device is configured to determine a flow rate of the infusion fluid based on the pressure difference across the filter membrane and the current between the electrodes. For example, a continuous infusion can thus be monitored.

[0018] Determining the flow rate is based on a linear relationship between flow rate and zeta potential, which can be determined using the pressure difference across the filter membrane and the current between the electrodes.

[0019] The ratio between the measured current between the electrodes and the flow between the electrodes in the steady state of the infusion fluid depends on the following parameters:

[0020] - Conductivity of the infusion fluid - Surface area of ​​the infusion filter, in particular the surface area of ​​the infusion filter per linear segment of the infusion filter in the direction of flow,

[0021] - Flow potential of the infusion filter.

[0022] The real-world environmental conditions under which medical procedures are typically performed allow the conductivity of the infusion fluid and the surface area of ​​the infusion filter to be considered constant. The flow potential depends on the following parameters:

[0023] - Relative dielectric constant of the infusion fluid,

[0024] - Viscosity of the infusion fluid,

[0025] - Zeta potential of the infusion fluid,

[0026] - Pressure difference across the filter membrane.

[0027] The parameters relative dielectric constant of the infusion fluid, viscosity of the infusion fluid and zeta potential of the infusion fluid can again be considered constant during the operation of the infusion system.

[0028] The pressure difference across the filter membrane depends, for example, on the flow profile and its laminarity, and therefore cannot be considered constant. However, the pressure difference can be measured by the pressure sensor.

[0029] Based on this, the following relationship can be derived between the measured current between the electrodes and the flow rate: where I_electrical is the measured electric current between the electrodes, I_flow is the flow rate of the infusion fluid through the infusion system, C describes all constant parameters in the form of an aggregated value, and AP is the measured pressure difference across the filter membrane.

[0030] Since C is constant and both I_electrical and AP can be measured, the flow rate can be determined based on this.

[0031] The linearity of the relationship between flow rate and zeta potential basically applies in the case that the measurement of electric current and differential pressure can be considered linear.

[0032] The determination of the flow rate is therefore largely independent of environmental influences such as temporary temperature changes, flow laminarity, and changes in the flow profile. In particular, the latter two parameters are only linear within very narrow flow ranges. The described method according to the present invention is therefore easier to implement than, for example, a method that would require compensation for changes in the flow profile or flow laminarity.

[0033] According to one embodiment, the infusion system, in particular the computing unit, is configured to output a signal for controlling a display device, wherein the display device is configured to output at least one piece of information. The display device may also be part of the infusion system. The information that can be output via the display device includes, for example, a value of the measured current and / or the rate of change of current and / or the flow rate, and / or an indicator relating to one of the aforementioned values, for example, a color indicator or a text-based indicator.

[0034] Further embodiments relate to an infusion line for an infusion system according to the described embodiments, the infusion line comprising an infusion filter with a filter membrane, wherein an electrode is arranged at each end of the filter membrane opposite the end in the direction of flow. Advantageously, the electrodes can also be arranged at the ends. For example, each electrode can be formed by coating edge regions at the respective end of the filter membrane with a conductive material. The infusion line can also include a measuring device for detecting the pressure difference across the filter membrane, for example, a strain gauge-based pressure sensor.

[0035] Further embodiments relate to a filter membrane for an infusion line according to the described embodiments, wherein an electrode is formed on the filter membrane by a coating with a conductive material at the edges of the membrane at opposite ends in the direction of flow of the infusion fluid. Further embodiments relate to a method for operating an infusion system according to the described embodiments, wherein a measurable current is detected between the electrodes of the infusion system by the infusion fluid flowing in the infusion line. The detected current or rate of change serves as a detection criterion for a bolus infusion.

[0036] According to one implementation, a pressure difference across the filter membrane is detected, and based on the detected current between the electrodes and the detected pressure difference between the electrodes, a flow rate of the infusion fluid flowing in the infusion line is determined within the infusion system. Determining the flow rate serves to monitor the duration of the infusion.

[0037] According to one implementation form, the method includes a step for outputting a signal to control a display device, wherein the display device is configured to output at least one piece of information.

[0038] In a further development of the foregoing inventive concept, an application can also be provided in which a voltage is applied across the electrodes of the infusion system in order to generate a current flow and maintain a specific flow rate of the infusion fluid in the infusion system. For example, a low flow rate can be maintained in this way, particularly to prevent clogging of the infusion line. Further advantages will become apparent from the description and the accompanying drawing, which illustrates exemplary embodiments of the invention.

[0039] Fig. 1 shows in schematic form an infusion system for use in healthcare.

[0040] The infusion system is a medical device for connecting an infusion container (not shown) to a parenteral access point, for example, an intravenous access point (not shown). In addition to the components shown in Fig. 1 and described below, the infusion system may include other components not shown, such as a drip chamber, a flow regulator, and a connection connector.

[0041] According to Fig. 1, the infusion system 10 in the example comprises an infusion line 12 through which an infusion solution 14 flows during operation of the infusion system 10. The infusion line includes an infusion filter 6 with a filter membrane 18. The filter membrane 18 is, for example, a cellulose or polysulfone membrane, which are used in infusion or dialysis systems. An electrode 22 is arranged at each of the ends 20 of the filter membrane 18 opposite each other in the direction of flow. A current I can be measured via a measuring device 24. eiectricai between the electrodes.

[0042] Each electrode is formed, for example, by coating edge regions 26 at the respective end 20 of the filter membrane 18 with a conductive material. In this example, the electrodes 22 extend over the entire cross-section of the filter membrane 18. According to the example, the infusion system 10 further includes a measuring device 28 for detecting the pressure difference AP across the filter membrane 18. According to the illustrated embodiment, the measuring device 28 for detecting the pressure difference AP comprises a strain gauge-based pressure sensor 30. For example, a strain gauge 32 is arranged on each side of the filter membrane 18 in the infusion line 12, particularly at or on a respective end 20 of the filter membrane 18.

[0043] The infusion system 10 further includes a computing unit 34. The computing unit 34 is designed to calculate, based on the pressure difference AP and the current I eiectricai to determine a flow rate of the infusion fluid 14 between the electrodes 22 .

[0044] According to one embodiment, the infusion system 10, in particular the computing unit 34, may be configured to output a signal 36 for controlling a display device 38, wherein the display device 38 is configured to output at least one piece of information 40. The display device 38 may also be part of the infusion system 10. The information 40 that can be output via the display device includes, for example, a value of the measured current and / or the rate of change of current and / or the flow rate, and / or an indicator relating to one of the aforementioned values, for example, a color indicator or a text-based indicator.

Claims

Patent claims 1. Infusion system (10) with an infusion line (12) , the infusion line (12) comprising an infusion filter (16) with a filter membrane (18) , characterized in that an electrode (22) is arranged at each of the ends (20) of the filter membrane (18) opposite each other in the direction of flow of an infusion fluid (14) , wherein the infusion system (10) comprises at least one measuring device (24) for detecting a current between the electrodes (22).

2. Infusion system (10) according to claim 1, wherein a respective electrode (22) is formed by coating edge regions (26) at the respective end (20) of the filter membrane (18) with a conductive material.

3. Infusion system (10) according to one of claims 1 or 2, wherein the infusion system (10) comprises at least one measuring device (28) for detecting a pressure difference across the filter membrane (18).

4. Infusion system (10) according to claim 3, wherein the measuring device (28) for detecting the pressure difference comprises a strain gauge, DMS,-based pressure sensor (30).

5. Infusion system (10) according to one of claims 3 or 4, wherein the infusion system (10) comprises a computing device (34), wherein the computing device (34) is configured to calculate, based on the pressure difference across the filter membrane and the current between the electrodes (22) to determine a flow rate of the infusion fluid (14) in the infusion system (10).

6. Infusion system (10) according to claim 5, wherein the computing device (34) is configured to determine the flow rate Ifi ow based on the formula to determine where I_electrical is the measured electric current between the electrodes (22), I_flow is the flow rate of the infusion fluid (12) through the infusion system (10), C describes constant parameters in the form of an aggregated value, and AP is the measured pressure difference across the filter membrane (18).

7. Infusion line (12) for an infusion system (10) according to one of claims 1 to 6, comprising an infusion filter (16) with a filter membrane (18) , characterized in that an electrode (22) is arranged at each of the ends (20) of the filter membrane (18) opposite each other in the direction of flow.

8. Filter membrane (18) for an infusion line (12) according to claim 7, wherein an electrode (22) is formed on the filter membrane (18) by a coating with a conductive material from edge areas (26) at ends (20) of the filter membrane (18) opposite each other in the direction of flow of an infusion fluid (14).

9. Method for operating an infusion system (10) according to one of claims 1 to 6, wherein infusion fluid flowing in the infusion line (12) (14) a measurable current is detected between the electrodes (22) of the infusion system (10).

10. Method according to claim 9, wherein a pressure difference across the filter membrane (18) is detected and, based on the detected current between the electrodes (22) and the detected pressure difference across the filter membrane, a flow rate of the infusion fluid (14) flowing in the infusion line (12) in the infusion system (10) is determined.

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