Self-removal detection device, sensor sheet and data processing system used in the device, and self-removal prevention system

Abstract

To provide a self-removal prevention system capable of preventing self-removal by detecting a sign of self-removal in advance and predicting it in advance.SOLUTION: A self-removal prevention system 1 includes: a deformable sheet-shaped sensor sheet 10 that has individual electrodes 2 distributed two-dimensionally, disposed on an outer surface side of a skin surface 99, with at least a part of a medical instrument 9 installed on the skin surface 99 interposed therebetween, for measuring capacitance between the skin surface 99 and the individual electrodes; a data processing device 20 that receives measurement data from the electrodes 2 of the sensor sheet 10 and calculates a capacitance distribution corresponding to the distribution of the electrodes 2 in time series from the measurement data; and alarm means 30 that notifies of a sign of removal. The data processing device 20 obtains a capacitance change distribution representing a temporal variation between a capacitance distribution in an initial state when the medical instrument 9 is placed on the skin surface 99 and a capacitance distribution after the initial state, and detects a sign of the medical instrument 9 being removed from the skin surface 99 using the capacitance change distribution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a self-removal detection device that detects the detachment of a medical instrument from a living body, a sensor sheet and a data processing device used in the device, and a self-removal prevention system. [Background technology]

[0002] In the medical field, there has long been a problem of patients unintentionally removing or unplanned self-removal of medical devices such as intravenous catheters and tubes placed along the skin surface of living bodies, and reducing the occurrence of such accidents has been an issue. For example, data shows that there are 2.27 cases of self-removal of intravenous tubes per 100 days of intubation. Cases such as the removal of blood transfusion tubes or tracheostomy tubes can lead to serious accidents.

[0003] Removal accidents occur for many reasons. Possible countermeasures include increasing the number of patrols, strengthening surveillance with cameras, and physical restraints. However, these countermeasures not only increase the burden on both nurses and patients, but also do not eliminate the problem of delayed detection of accidents. Therefore, it is necessary to detect or prevent removal accidents without patrols or surveillance.

[0004] As a technique for detecting self-removal, a technique is known in which a combination pair of a magnetic sensor and a permanent magnet is used to detect tube detachment (see, for example, Patent Document 1).

[0005] In addition, a device is known that, when a patient's fingers touch or approach a sensor electrode attached to the intubation section, the sensor electrode detects the approach through a change in capacitance and issues an alert, thereby preventing the intubation section from being removed (see, for example, Patent Document 2).

[0006] Also known is a device that detects the pulling action of a tube by detecting the deformation of the shape of a tube support portion that occurs when the tube is pulled using an expansion sensor, and issues a removal alarm (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-159035 [Patent Document 2] Japanese Patent Publication No. 2020-118626 [Patent Document 3] Japanese Patent Publication No. 2022-165721 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology disclosed in the above-mentioned Patent Document 1 is a system that sounds an alarm when the tube becomes detached from a fixed sensor, but the intubation position and the sensor are separated, and the detection occurs after the tube is removed by the patient. Furthermore, it is necessary to attach sensors to both the tube and the body and to adjust their positions, making the operation complicated.

[0009] The device disclosed in the above-mentioned Patent Document 2 is thought to react simply by touching it or bringing your hand close to it, so there are problems with usability and reliability.

[0010] The device disclosed in the aforementioned Patent Document 3 uses an expansion sensor to determine the relationship between the amount of pulling and removal using a threshold value, but the output of the expansion sensor is a single measurement value. Therefore, even if the complicated tasks of attaching the expansion sensor, adjusting it, and setting the threshold value are carefully performed in the medical field, it is thought that there is a limit to the ability to detect various pulling movements using a single measurement value.

[0011] The present invention aims to solve the above-mentioned problems and to provide a self-removal detection device that detects signs of self-removal in advance, a sensor sheet and data processing device used in the self-removal detection device, and a self-removal prevention system. [Means for solving the problem]

[0012] In order to achieve the above object, the self-removal detection device of the present invention comprises: A self-removal detection device that detects unplanned removal of a medical instrument placed along the skin surface of a living body, comprising: a deformable sheet-like sensor sheet that is placed on the outer surface of the skin surface with at least a part of the medical device placed on the skin surface in between, and has a plurality of individual electrodes that are two-dimensionally distributed to measure capacitance between the skin surface and the sensor sheet; a data processing device that acquires measurement data from the electrodes of the sensor sheet and obtains time-series data of a capacitance distribution corresponding to a distribution of the electrodes from the measurement data; The data processing device is characterized in that it detects signs of the medical device being removed from the skin surface or the result of removal based on temporal variations in the capacitance distribution from the initial state in which the medical device is placed on the skin surface.

[0013] In this self-removal detection device, The sensor sheet is characterized in that it is integrated with a protective fixation sheet that fixes the medical device to the skin surface, and / or is used in combination with a medical sheet that fixes the medical device to the skin surface.

[0014] In this self-removal detection device, The data processing device is characterized in that it detects the signs or removal results using the results of learning the temporal fluctuations in the capacitance distribution for a series of states regarding the placement state of the medical device on the skin surface, from the initial state to the end of use of the medical device.

[0015] In this self-removal detection device, The data processing device is characterized in that it records or outputs for recording time series data of the capacitance distribution, or in addition to the time series data of the capacitance distribution, data on the surrounding environment in which the living body is located during a series of states from the initial state to the end of use of the medical device, together with time data.

[0016] In this self-removal detection device, The sensor sheet is characterized in that it is configured so that unnecessary electrodes can be cut away from the two-dimensionally distributed electrodes, or cut into a shape suitable for fixing the medical device.

[0017] In order to achieve the above object, the present invention provides the sensor sheet, characterized in that it is used in the self-removal detection device. In order to achieve the above object, the present invention provides a data processing device that is used in the above self-removal detection device. In order to achieve the above object, the self-removal prevention system of the present invention comprises: The self-removal detection device of the present invention; an alarm means for notifying an external device of the self-removal detection device that the data processing device has detected the sign of removal or the result of removal; The present invention is characterized by comprising: [Effects of the Invention]

[0018] According to the self-removal detection device and self-removal prevention system of the present invention, the sensor sheet is deformable, allowing it to be easily installed along the shape of the medical instrument when installing the medical instrument in the medical field. Furthermore, because the data processing device detects signs of self-removal, it is possible to reduce the need for nurse patrols, camera monitoring, and restraints on the patient. Furthermore, because the data processing device monitors the temporal fluctuations in the capacitance distribution between the skin surface on which the medical instrument is installed and the sensor sheet, it is possible to detect various signs of self-removal in advance, predict self-removal in advance, and prevent self-removal. As a result, the self-removal detection device and self-removal prevention system of the present invention 1) reduce the psychological and physical burden on the patient, 2) reduce the burden on medical personnel who install the sensor sheet during treatment, and 3) enable advance prediction of self-removal rather than detection after the fact, and issue an alarm based on the advance prediction. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing an example of use of a self-removal prevention system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of a sensor sheet constituting the self-removal prevention system. [Figure 3] FIG. 10 is an exploded plan view illustrating the integration of the sensor sheet and the attached protective sheet for fixing. [Figure 4] FIG. [Figure 5] FIG. 10 is a plan view showing how the placement state of the medical instrument is detected by the sensor sheet that constitutes the self-removal prevention system. [Figure 6] This figure shows how one of the electrodes that make up the sensor sheet of the self-removal prevention system moves away from the skin surface over time, as a result of the change in pulse count corresponding to the change in capacitance detected by the electrode. [Figure 7] 4 is a flowchart showing the flow of processing from the start to the end of use of the self-removal prevention system. [Figure 8] FIG. 10 is a perspective view illustrating a method for evaluating a prototype of a sensor sheet that constitutes the self-removal prevention system of the present invention. [Figure 9] (a) is a perspective view of the initial state in which a urethane tube, assumed to be a dummy medical device, is fixed to the evaluation table using a prototype sensor sheet, and (b) is a distribution diagram corresponding to the capacitance distribution detected by the sensor sheet in the state of (a). [Figure 10] (a) is a perspective view of the state in which the urethane tube is pulled upward and the sensor sheet prototype is peeled off from the evaluation stand, and (b) is a distribution diagram corresponding to the capacitance distribution detected by the sensor sheet in the state of (a). [Figure 11] (a) is a perspective view of the initial state in which a urethane tube, assumed to be a dummy medical device, is fixed to the evaluation table using a prototype sensor sheet, and (b) is a distribution diagram corresponding to the capacitance distribution detected by the sensor sheet in the state of (a). [Figure 12] (a) is a perspective view of the state in which the urethane tube is moved along the surface of the sensor sheet and the sensor sheet is peeled off from the evaluation table, and (b) is a distribution diagram corresponding to the capacitance distribution detected by the sensor sheet in the state of (a). DETAILED DESCRIPTION OF THE INVENTION

[0020] A self-removal prevention system according to one embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2 , the self-removal prevention system 1 includes a self-removal detection device 1A, which is composed of a sensor sheet 10 and a data processing device 20, and an alarm unit 30. The data processing device 20 includes a data acquisition unit 20A and a control unit 20B. The self-removal detection device 1A detects signs of removal or unplanned removal of a medical instrument 9 placed along the skin surface 99 of a living body. The self-removal prevention system 1 uses the alarm unit 30 to report the detection result to the outside of the self-removal detection device 1A, i.e., the outside of the self-removal prevention system 1, thereby preventing unplanned removal or taking appropriate measures after removal. The medical instrument 9 is, for example, a catheter and its accessories that receives a solution supplied via a tube 9a and delivers the solution into the patient's body.

[0021] (sensor sheet) The sensor sheet 10 is a group of sensors configured in a deformable sheet shape, and is placed on the outer surface of the skin surface 99, sandwiching, i.e., placing at least a portion of, the medical instrument 9 placed on the skin surface 99. The sensor sheet 10 is provided with a multi-electrode array electrode, in which a large number of individual electrodes 2 are distributed two-dimensionally to form a multi-electrode array electrode, in order to measure the electrostatic capacitance between the sensor sheet 10 and the skin surface 99 when in use. The electrodes 2 in this embodiment are arranged in a two-dimensional array with approximately constant spacing between them. Note that the spacing between the electrodes 2 does not necessarily need to be approximately constant, and may be set to an appropriate spacing and distribution depending on the shape of the medical instrument 9 and the installation situation.

[0022] As shown in Figures 2 and 3, the sensor sheet 10 is a flexible printed circuit board (FPC) and is used together with the fixing protection sheet 4. The sensor sheet 10 is a deformable sheet, meaning that it can flexibly deform together with the fixing protection sheet 4. The sensor sheet 10 includes an insulating layer, which is an insulating substrate 3 with a contoured shape, and a conductor layer, such as patterned electrodes 2. The insulating substrate 3 is an insulating film made of polyimide or polyester. The sensor sheet 10 is produced from a blank sheet substrate, in which a conductor layer, such as pre-formed copper foil, is laminated on the pre-formed insulating substrate 3, using techniques such as printed wiring formation and cutting and forming. Therefore, the patterned conductor layer is supported by the insulating substrate 3. The conductor layer is formed thin enough to maintain the necessary electrical properties, thereby providing flexibility to the electrodes 2. The conductor pattern can be easily formed using common techniques such as resist coating, exposure, and etching.

[0023] The sensor sheet 10 of this embodiment includes a plurality of circular electrodes 2 and wiring patterns 2a individually connected to each electrode 2. The wiring patterns 2a are surface-treated to prevent corrosion and short-circuiting, for example, by coating with an insulating layer or coating agent. Ends of the wiring patterns 2a are aggregated to form a parallel terminal group 2b. The parallel terminal group 2b is a terminal that is inserted into and connected to a connector 21. The parallel terminal group 2b is backed and reinforced by an insulating substrate 3 on the back surface, as needed. The parallel terminal group 2b is surface-treated to prevent corrosion, for example, by plating, as needed. The shape of the electrodes 2 does not necessarily have to be circular, and any shape may be used as long as the magnitude and distribution of the capacitance obtained from each electrode 2 can be measured with the required accuracy.

[0024] The electrode 2 is a sensor that forms a parallel-plate capacitor facing the skin surface 99 and measures the capacitance that depends on the distance from the skin surface 99. The surface of the electrode 2 is subjected to a surface treatment, for example, to prevent corrosion and to avoid system instability due to direct contact and conduction with the skin surface 99. The electrode 2 may have cuts to facilitate three-dimensional deformation.

[0025] The electrodes 2 are gathered together by a dendritic wiring pattern 2a and individually connected to a group of parallel terminals 2b at the end. The parallel terminals 2b are then individually connected to a data acquisition unit 20A of a data processing device 20 via general-purpose or dedicated connectors 21. The insulating substrate 3 is dendritic, conforming to the contours of the electrodes 2 and wiring pattern 2a, in order to facilitate three-dimensional deformation of the sensor sheet 10 and reduce the distance between each electrode 2 and the skin surface 99, thereby increasing sensor sensitivity. The wiring pattern 2a is also designed to reduce stray capacitance. Multiple parallel terminal groups 2b may be provided for one sensor sheet 10, and the number of connectors 21 used may be increased or decreased as needed.

[0026] The sensor sheet 10 may be cut, for example, along cutting lines a and b to remove unnecessary electrodes 2 from the two-dimensionally distributed electrodes 2, for example, to facilitate installation of the medical device 9 during use. Similarly, the fixing protective sheet 4 may be cut or removed to form a shape suitable for fixing the medical device 9. Furthermore, in order to facilitate three-dimensional deformation during use, notches may be made in the electrodes 2. A dendritic pattern can be easily cut to fit the size of the medical device 9. However, cutting is not necessary if the wiring patterns 2a are prepared to fit the respective standard sizes of various medical devices 9 from the beginning. Furthermore, although a dendritic pattern is used to aggregate the wiring patterns 2a so that they do not cross each other, this is not limiting.

[0027] As shown in the cross-sectional view of Figure 4, the fixing protective sheet 4 is used as a sheet for supporting the sensor sheet 10. The fixing protective sheet 4 may be, for example, a standard medical sheet or tape used in medical settings, such as a dressing or bandage, or may be formed using a sheet material with the same material and function as a medical sheet. The fixing protective sheet 4 is preferably one that has an adhesive layer protected by a removable covering film on one or both sides. The fixing protective sheet 4 supports the sensor sheet 10 by being adhered to the insulating substrate 3 side of the sensor sheet 10 via an adhesive layer 5 made of adhesive.

[0028] Unlike the conductive layers of the electrodes 2 and the insulating substrate 3, which are deformable but not stretchable, the fixing protective sheet 4 is made of a stretchable material. The fixing protective sheet 4 stretches and connects the gaps between the electrodes 2, the gaps between the electrodes 2 and the wiring patterns 2b, and the gaps between the wiring patterns 2b, thereby effectively utilizing the deformable structure of the sensor sheet 10 to easily install and fix the medical device 9 on the skin surface 99. Furthermore, the adhesive layer 5 of the fixing protective sheet 4, located in the gaps where the insulating substrate 3, electrodes 2, and wiring patterns 2a are not present, allows the sensor sheet 10 to adhere to the skin surface 99. The fixing protective sheet 4 may be provided sufficiently wide around the periphery of the sensor sheet 10, thereby enhancing the fixing function. In this way, the fixing protective sheet 4 is used together with the sensor sheet 10 as a sheet to fix the medical device 9 to the skin surface 99.

[0029] As a modification of the sensor sheet 10, the shape of the insulating substrate 3 may be a simple rectangle that does not depend on the shape and distribution of the electrodes 2 and wiring patterns 2a. To facilitate three-dimensional deformation of the sensor sheet 10, it is sufficient to form separation cuts or slits in the insulating substrate 3.

[0030] The fixing protective sheet 4 and the sensor sheet 10 may be configured and used in various ways, for example, as follows, depending on the structure, material, thickness, etc. The fixing protective sheet 4 may be placed on either side of the sensor sheet 10. The fixing protective sheet 4 may have adhesive layers 5 on both sides. The sensor sheet 10 may be configured and used in such a way that an insulating substrate 3 is interposed between the electrodes 2 and the skin surface 99. The sensor sheet 10 may be configured and used in such a way that a fixing protective sheet 4 is interposed between the electrodes 2 and the skin surface 99.

[0031] Various layer configurations of the sensor sheet 10 and the fixing protective sheet 4 relative to the skin surface 99 will now be described. The layer configuration in Figure 4 can be expressed as 99 / 10(2 / 3) / 4 using the reference symbols for each layer. Here, the diagonal line / indicates an adhesive layer that bonds each layer together. The sensor sheet 10 and the fixing protective sheet 4 may be used in any of the following four layer configurations represented using this notation. 99 / 10(2 / 3) / 4, 99 / 10(3 / 2) / 4, 99 / 4 / 10(2 / 3), 99 / 4 / 10(3 / 2).

[0032] The fixing protective sheet 4 and the sensor sheet 10 may be supplied to the medical site in an integrated state, or may be supplied to the medical site in a separated state and then integrated at the medical site. Alternatively, only the sensor sheet 10 may be supplied, and the medical instrument 9 may be placed on the skin surface 99 together with the sensor sheet 10 using a medical sheet, tape, or other material that replaces the fixing protective sheet 4. Alternatively, the medical instrument 9 and sensor sheet 10 may be placed on the skin surface 99 using a combination of the fixing protective sheet 4 integrated with the sensor sheet 10 and any medical sheet.

[0033] The sensor sheet 10 in the self-removal prevention system 1 is a disposable medical product that is not reused, similar to the fixing protective sheet 4. The sensor sheet 10 can be separated from the data acquisition unit 20A of the data processing device 20 by removing the parallel terminal group 2b from the connector 21. The sensor sheet 10 is a structure that places emphasis on the pattern shape, and can be mass-produced at low cost using materials and manufacturing techniques that are well known as general industrial products. The data acquisition unit 20A is an advanced electronic component that is reused.

[0034] (Data processing device: data acquisition unit and control unit) The data processing device 20 acquires measurement data from each electrode 2 of the sensor sheet 10 and calculates the capacitance distribution corresponding to the distribution of the electrodes 2 from the measurement data. The data acquisition unit 20A of the data processing device 20 is connected to the control unit 20B of the data processing device 20 via a wireless or wired connection. The data acquisition unit 20A is a field device placed near the sensors (electrodes 2) to quickly digitize weak signals. Since the digitized measurement data can be transmitted to a remote device without degradation, the control unit 20B can be a remote device and can be remotely located at any location. In this embodiment, the control unit 20B is equipped with an alarm means 30. A relay device may also be provided between the data acquisition unit 20A and the control unit 20B. The relay device may be equipped with devices such as a power source, an operation and display panel, and an input / output device as necessary, and may be installed, for example, on a mobile pole placed next to a bed.

[0035] The data acquisition unit 20A includes a connector 21, a sensor controller 22, and a transmitting / receiving device 23 (also referred to as an input / output device 23). The parallel terminal group 2b is inserted into the connector 21, thereby electrically connecting each electrode 2 of the sensor sheet 10 to the sensor controller 22. The transmitting / receiving device 23 is used for data communication between the data acquisition unit 20A and the control unit 20B. The transmitting / receiving device 23 may be, for example, a data communication device or communication means based on a standardized general-purpose specification.

[0036] The transmitting / receiving device 23 may be a terminal or a transmitting antenna that outputs an alarm signal to operate a warning light, an alarm speaker, a display monitor, a mobile terminal, or other notification device, or may be a device dedicated to transmission. The transmitting / receiving device 23 may be configured to output an alarm signal, so that it functions as an alarm means 30 for notification to the outside.

[0037] The sensor controller 22 is equipped with a microcomputer for the capacitive touch sensor (such as a sensor IC, described later), and uses this microcomputer to periodically or irregularly acquire a group of measurement data relating to the distribution of capacitance from each electrode 2 of the sensor sheet 10 as time-series data. This time-series data is data in chronological order, and it is sufficient that the measurement time is known; the measurement intervals do not need to be constant. It is preferable that the capacitance measurement by the electrode 2 is digitized at a position close to the electrode 2 to reduce the influence of stray capacitance and the like. The acquired measurement data is transmitted to a remote control unit 20B.

[0038] The control unit 20B is configured, for example, by a general personal computer (PC), and receives the measurement data, and calculates a capacitance distribution corresponding to the distribution of the electrodes 2 from the measurement data and displays it on a monitor screen. The control unit 20B calculates a capacitance change distribution that represents the temporal variation between the capacitance distribution in the initial state when the medical instrument 9 is placed on the skin surface 99 and the capacitance distribution after the initial state. The control unit 20B uses the capacitance change distribution to detect signs that the medical instrument 9 is being removed from the skin surface 99.

[0039] The control unit 20B is used to present the status and measurement data of the data acquisition unit 20A to relevant parties through a monitor screen, to store the measurement data transmitted from the data acquisition unit 20A as a database, to display the capacitance distribution, etc. Furthermore, the control unit 20B displays signs of self-removal, displays the results of unexpected removal (referred to as removal results), issues warnings, notifies relevant parties, etc.

[0040] The above-mentioned display, issuance of an alarm, notification, etc. may be performed directly by the alarm means 30, or may be performed by utilizing existing or dedicated equipment in response to an alarm signal output by the alarm means 30. The alarm means 30 may be configured appropriately depending on the scale and installation environment of the self-removal prevention system 1 to which it is applied.

[0041] The control unit 20B may be configured as a mobile device such as a smartphone or tablet PC. The control unit 20B does not need to be highly functional and may be a microcomputer or SBC (single board computer) with various communication functions and Wi-Fi functions. The control unit 20B may be a dedicated device with a minimal configuration that has the processing functions and performance required by the user.

[0042] As another configuration of self-removal detection device 1A and self-removal prevention system 1, a configuration without using control unit 20B may be used. In this case, for example, data processing device 20 configured as a standalone device consisting of only data acquisition unit 20A is provided with a function for processing measurement data as well as a function for issuing a warning or informing relevant parties based on the detection of signs of self-removal or the removal result, i.e., an alarm function by alarm means 30. If necessary, a transmitting / receiving device 23 of an appropriate size, such as an external connection terminal to which a PC or a monitor screen can be connected, may be provided.

[0043] (Example of capacitance distribution) Fig. 5 shows a schematic diagram of the capacitance distribution in the initial state when the medical device 9 including the tube 9a is placed on the skin surface 99. In this diagram of the initial state, the white electrode 2 indicates an electrode placed close to the skin surface 99, and the gray electrode 2x indicates an electrode that is separated from the skin surface 99 due to the medical device 9 being interposed between the skin surface 99 and the electrode 2. Fig. 5 shows that the placement state of the medical device 9 including the tube 9a is obtained by the capacitance distribution of the electrode 2x.

[0044] Based on the capacitance distribution in the initial state shown in FIG. 5 as a reference, signs of removal of the medical instrument 9 from the skin surface 99 or removal results are detected based on the increase in the number of electrodes that have become electrodes 2x over time. The self-removal prevention system 1 measures and monitors changes in capacitance between each electrode 2 of the sensor sheet 10 and the skin surface 99. Therefore, in terms of measuring the capacitance between the skin and the electrodes, the self-removal prevention system 1 can use technology similar to capacitance measurement in capacitive touch sensors on operation display screens such as smartphones. However, while touch sensor technology is primarily used to detect whether or not a touch has occurred, the sensor sheet 10 is used to detect separation from the initial state in which it is close to the skin surface 99, and therefore the detection in the present invention is separation detection, an application of touch detection.

[0045] Therefore, a commercially available sensor IC for a capacitive touch sensor can be suitably used as the sensor controller 22. Such a sensor IC has a multi-channel configuration with multiple terminals that enable input and output to and from multiple electrodes 2.

[0046] (Method of measuring capacitance and example of measurement over time) Figure 6 shows an example of the change in capacitance measured using a commercially available sensor IC. There are two methods for measuring capacitance: a self-capacitance method and a mutual capacitance method, depending on the electrode structure. The capacitance measurement of the capacitor formed by the electrode 2 of the sensor sheet 10 is a self-capacitance method. In addition, methods for measuring the minute capacitance of the capacitor formed by the electrode 2 include a method of measuring the impedance of the capacitor and a method of charging and discharging the capacitor and measuring the time it takes, and the self-removal prevention system 1 may use either of these methods.

[0047] Figure 6 shows the results of measurements taken by charging and discharging a capacitor and measuring the time required. To measure the capacitance, a square-wave pulse train is applied to electrode 2, i.e., the capacitor formed by electrode 2, to charge it. The number of counts required for charging is measured, and the capacitor is discharged after charging is complete. The count number corresponds to the amount of charge used to charge the capacitor, and therefore the capacitance of the capacitor. Measurements are performed repeatedly, charging and discharging at predetermined intervals to obtain count data, i.e., time-series data, and the change in count number over time is monitored. In this measurement example, the count number decreases after approximately 70 seconds, indicating that electrode 2 has separated from the skin surface 99. These measurement results enable detection of electrode 2 separation from the skin surface 99. In an embodiment of the self-removal prevention system 1, count numbers are measured for all associated electrodes 2 at predetermined intervals, and the number and distribution of separated electrodes 2 are monitored at each interval.

[0048] (Processing flow in the self-removal prevention system) 7 and 1, we will explain the process flow from the start to the end of use of the self-removal prevention system 1. Use of the self-removal prevention system 1 begins, for example, by temporarily fastening the medical instrument 9 and the tube 9a to the patient's skin surface 99, and then fixing and placing the sensor sheet 10 together with the medical instrument 9 on the patient's skin surface 99 (S1).

[0049] The sensor sheet 10 is preferably integrated with the fixing protective sheet 4 or integrated in the preparation stage prior to installation, but in addition to, or without being limited to, any medical fixing member (medical sheet) may be used to install the sensor sheet 10. The installation work of the sensor sheet 10 is completed when the sensor sheet 10 is fixed to the skin surface 99 and connected to the data processing device 20.

[0050] The self-removal prevention system 1 checks the specified operation by turning on the power to the data processing device 20 (data acquisition unit 20A, control unit 20B), acquires measurement data of the capacitance in the initial state, and displays it on a monitor screen, etc. The person involved in the system setup checks the displayed data and, if necessary, adjusts the installation state or reinitializes, etc., to confirm that the system is properly installed (S2).

[0051] Whether the installation is normal or not is determined by looking at the distribution of capacitance in the initial state measured at each electrode 2 of the sensor sheet 10 (see, for example, the initial state shown in FIG. 5). If the installation is not normal, the cause is investigated and normalization work is carried out.

[0052] The capacitance measurement value has an arbitrary unit such as the number of pulse counts, etc. The capacitance distribution is displayed on the monitor screen using, for example, three color levels, with the state of the electrode 2 relative to the skin surface 99 indicated by blue (normal) if in close contact, yellow (caution) if in close proximity, and red (abnormal) if completely floating.

[0053] The self-removal prevention system 1 periodically or irregularly acquires measurement data as time-series data and checks for signs of self-removal or the result of removal based on the temporal fluctuation of the capacitance distribution (S3). The relevant medical personnel check the monitor screen of the data processing device 20 as appropriate.

[0054] The self-removal prevention system 1 or a relevant person determines whether there is a significant time variation in the measured capacitance distribution and whether the variation indicates a self-removal or is the result of removal (S4).

[0055] In step (S4), if it is determined that there is a significant time variation in the measured capacitance distribution and that there is a sign of self-removal or that there is a result of removal (Yes in S4), a notification process or an alert process is performed to that effect. If the determination is made by the self-removal prevention system 1, the alarm means 30 will automatically notify the user, or if the determination is made by a relevant person, the alarm will be sent to a predetermined contact point or a predetermined relevant area will be notified by issuing an alarm or flashing a light, etc., and the relevant person will check the site and take appropriate action (S5).

[0056] In step (S4), if it is determined that there is no significant temporal variation in the measured capacitance distribution (No in S4), or after step (S5), it is determined (S6) whether monitoring has ended (end of use of the self-removal prevention system 1). If there is no significant temporal variation (No in S4), monitoring is automatically continued, and the process from step (S3) is repeated.

[0057] End of monitoring (Yes in S6) is usually a forced end caused by an interruption by a relevant person. End of monitoring is the end of use of the self-removal prevention system 1, such as the normal end or interruption of use of the medical device, the resetting of the medical device and sensor sheet, or other reasons.

[0058] If it is determined in step (S6) that monitoring has ended (Yes in S6), the self-removal prevention system 1 records the measurement values ​​and other data in a predetermined database, or outputs or transmits them for recording (S7), and use of the self-removal prevention system 1 ends. The data recorded, output, or transmitted by the data processing device 20 is basically data in which time data has been added to time-series data of capacitance distribution. The data recorded, output, or transmitted by the data processing device 20 may also be data in which time data has been added to time-series data of capacitance distribution and data related to the surrounding environment in which the living body is located throughout a series of states from the initial state to the end of use of the medical device, or any other data.

[0059] The determination of the presence or absence of signs of self-removal and the result of removal in step (S4) above can be made, for example, based on the rate of increase in the number of electrodes corresponding to yellow, red, or yellow and red relative to the total number of electrodes 2 used in the measurement. When making this determination, it is effective to consider the distribution in which the number of electrodes corresponding to yellow and red increases in relation to the initial positioning state of the medical instrument 9. This can be considered a signal processing or image processing issue, and artificial intelligence (AI) can be utilized.

[0060] The self-removal prevention system 1 may also have an artificial intelligence (AI) function for machine learning using the measurement values ​​and other data recorded in the database in the above-mentioned step (S7) and / or a function for utilizing the results of learning by such machine learning. The learning content may be, for example, the time change in capacitance distribution for a series of states from the initial state to the withdrawal state of the medical device 9, regarding the state of attachment of the medical device 9 to the skin surface 99.

[0061] The signs of self-removal or the results of removal can be suitably detected using the results of learning by artificial intelligence (AI) of a large amount of accumulated measured data regarding the time change in capacitance distribution from the initial installation state to self-removal or removal due to normal termination. Data processing device 20 may have a function for performing such machine learning, a function for using the results learned by such machine learning, or a function for using the results learned by machine learning performed outside self-removal prevention system 1.

[0062] Furthermore, while monitoring is being performed by the self-removal prevention system 1, the measurement values ​​and other data necessary to determine whether or not the state is normal and there are no signs of self-removal or removal results are stored in the storage device, but after monitoring has ended, these data are not essential for the operation of the system. Therefore, when it is determined that monitoring has ended (Yes in S6), the self-removal prevention system 1 may be terminated without performing the processing of step (S7).

[0063] The self-removal prevention system 1 may include a database for multiple living organisms, which records data on the surrounding environment in which the living organism is located as situation data along with time data for a series of states from the initial state to the medical instrument removal state. This database is a collection of various available information and may include a wide range of information, including information based on measurement data, information based on empirical knowledge, and information on the history and origin of the living organism. The data processing device 20 may use such a database to calculate or use artificial intelligence (AI) derived associations (e.g., coefficients, scales, evaluation values, risk levels, correlation coefficients) related to signs of removal, and use these results to detect signs of self-removal. The data processing device 20 may, for example, set a warning time period based on the calculated or derived associations to perform detailed detection processing for signs of self-removal.

[0064] Here, the relationship between the self-removal prevention system 1 and the self-removal detection device 1A will be described. The self-removal detection device 1A can be used alone. In this case, since the self-removal detection device 1A is a detection device, it naturally includes means for externally presenting, providing, notifying, or issuing an alert regarding the detection results, such as a transceiver device 23, so that the detection results can be utilized. The self-removal prevention system 1 is configured by combining the self-removal detection device 1A with alarm means 30. The alarm means 30 is means for notifying external parties of the self-removal detection device 1A that the data processing device 20 constituting the self-removal detection device 1A has detected a sign of removal of the medical instrument 9 from the skin surface 99 or the result of removal. Therefore, when used as a component of the self-removal prevention system 1, the self-removal detection device 1A may or may not include means for externally presenting, providing, or notifying the detection results.

[0065] The self-removal prevention system 1 of this embodiment has the following advantages. By monitoring the temporal variation in capacitance distribution between the sensor sheet 10 and the skin surface 99 on which the medical instrument 9 including the tube 9a is placed, signs of self-removal can be detected in advance, predicting self-removal in advance and preventing self-removal. Because the sensor sheet 10 is a deformable, flexible sheet, it can be easily installed along the shape of the medical instrument 9 when installing the medical instrument 9 in a medical setting. Because the data processing device 20 detects signs of self-removal, it is possible to reduce the need for medical personnel to patrol the area, monitor with camera footage, and restrain the patient. As a result, the self-removal prevention system 1 of this embodiment 1) reduces the psychological and physical burden on the patient, 2) reduces the burden on medical personnel who install the sensor sheet 10 during treatment, and 3) enables advance prediction of self-removal rather than detection after the fact and the issuance of an alarm based on the advance prediction.

[0066] According to the self-removal prevention system 1 of this embodiment, the sensor sheet 10 has a large number of electrodes 2 distributed two-dimensionally and is integrated with the fixing protective sheet 4, allowing it to be attached together when fixing the medical device 9 including the tube 9a. This eliminates the need to adjust the positioning of the electrodes 2 during installation. Because the sensor sheet 10 and the fixing protective sheet 4 are integrated, and the degree of peeling of the electrodes 2 (the degree of separation from the skin surface 99) is obtained as a capacitance change map, the amount of peeling can be directly used as a risk of removal. Signs of self-removal can be detected by judging the peeling state of the fixing protective sheet 4 before the tube 9a is removed from the body due to self-removal. Even if signs of self-removal cannot be detected due to the rapid progression of self-removal, the removal result can be detected based on multiple measurement data from the multiple two-dimensionally distributed electrodes 2, allowing for more reliable detection of the removal result than detection based on a single measurement data. Therefore, even after self-removal, the removal result can be detected in a short time, allowing for prompt and appropriate treatment.

[0067] From the change over time in the two-dimensional distribution of the capacitance of the parallel plate capacitor formed by each electrode 2 of the sensor sheet 10 and the skin surface 99, it is possible to detect events other than the electrode 2 or the fixing protective sheet 4 separating from the skin surface 99. For example, it is possible to read the change in the position of the medical instrument 9 including the tube 9a located between the fixing protective sheet 4 and the skin surface 99. For example, it is possible to detect the event of the tube 9a coming out from under the fixing protective sheet 4. In this case, the space where the tube 9a (relative dielectric constant = approximately 4) comes out becomes an air layer (relative dielectric constant = 1), which reduces the dielectric constant and therefore reduces the capacitance, and therefore it is possible to detect the event of the tube 9a coming out by measuring the capacitance with the electrode 2.

[0068] The sensor sheet 10 is a group of electrodes that constitute a capacitance-type sensor, and the initial value is the measured capacitance when the sensor sheet 10 is first attached to the patient's skin surface 99, for example. Examples of fluctuations in the measured value include a decrease in the measured capacitance from the initial value when the tube 9a is removed or the protective sheet for fixation 4 is peeled off, and an increase in the measured capacitance from the initial value when the patient touches the sensor sheet 10 with their fingers. By having the data processing device 20 or a separately used device learn (through machine learning using AI technology) the types of temporal fluctuations in the measured capacitance, such as a decrease or increase from the initial value, a self-removal prevention system 1 that can accurately detect signs of self-removal can be realized.

[0069] The self-removal prevention system 1 of this embodiment uses a multi-electrode array electrode in its sensor sheet 10, which can cover a wide area of ​​the skin surface. It is deformable and flexible, making it easy to attach to the patient, greatly helping to reduce the burden on both patients and medical professionals in medical settings. Furthermore, the removal status can be monitored in real time and the data can be stored in any device. Furthermore, by calculating the correlation between the patient's surrounding environment (temperature, humidity, air pressure, etc.) and time of day and signs of removal, it is possible to determine the alert period and establish a safe and detailed medical system. The data stored in the device is multi-dimensional data that combines event data in three-dimensional space, which incorporates temporal pattern changes in the two-dimensional distribution of measurement values, with surrounding environmental data, etc.

[0070] The self-removal prevention system 1 of this embodiment can be easily applied to medical instruments of different shapes because its sensor sheet 10 and data processing device 20 are highly scalable to accommodate multiple channels and large scale applications. In addition, the data processing device 20 can flexibly accommodate applications using technology similar to image recognition processing (AI technology) as software for detecting signs of removal.

[0071] The self-removal prevention system 1 of this embodiment basically performs automatic calibration using measurements taken at the start of operation, so there are no significant limitations on the installation method or location of the sensor sheet 10 at the site of use, allowing for flexible response in emergencies, etc. For example, while tapes are often cut according to the location of use in medical settings, the electrodes 2 of the sensor sheet 10 can be configured to be easily cut, and by clearly indicating the cuttable positions, it can be used more easily in clinical settings. Electrodes 2 that have been cut and removed are automatically excluded from processing by the data processing device 20, which processes the measurement data. The present application includes the sensor sheet 10 and data processing device 20 in the embodiment of the self-removal prevention system 1 or self-removal detection device 1A described above as the present invention, and further includes the sensor sheet and data processing device used in the self-removal detection device of the present invention as the present invention.

[0072] (Example) In proposing the self-removal prevention system of this application, a prototype sensor sheet was fabricated and evaluated for its ability to detect stretching and disconnection of tubes connected to medical instruments, as well as signs of self-removal of the medical instrument. When securing a medical instrument or tube to the skin, the medical instrument connected to the tip of the tube is generally inserted into the patient's body and secured with a medical dressing from above. The prototype sensor sheet was created with the assumption that touch sensors (electrodes) would be mounted in an array on the dressing used to secure such medical instruments.

[0073] The prototype sensor sheet has two layers: an electrode layer that makes up the sensor group, and a dressing layer that holds the electrode layer. The electrodes are placed on top of the tube, just like regular dressings. The electrodes that make up the touch sensor measure capacitance, which changes depending on the distance from the skin. The capacitance-type touch sensor's measurement value changes continuously depending on the proximity to the skin, making it possible to detect the location of tubes located under the dressing and electrodes (see Figure 5), as well as the detachment of the dressing and electrodes from the skin (see Figure 6).

[0074] Therefore, it is possible to detect the state in which the dressing material and electrode are about to detach before self-removal, and to realize advance detection of self-removal. Dressing materials are common in medical institutions and can be used without any problems in medical settings. Furthermore, when a patient pulls on the tube, for example, if the tube moves along the skin so that it is no longer under the electrode, the capacitance decreases even though the electrode does not move, making it possible to detect tube detachment. This type of detachment detection also makes it possible to detect (detect signs of) advance self-removal.

[0075] (Prototype sensor sheet and evaluation method) As shown in Figure 8, a prototype sensor sheet 80 and evaluation equipment were set up. Instead of a dressing material, a 0.16 mm thick polypropylene film with 1 mm thick double-sided adhesive tape attached was used. Copper foil tape (15 mm x 10 mm) was attached on top of this as the electrodes 2 of the touch sensor. Each electrode 2 was connected to the microcomputer 83 for acquiring sensor values ​​with a flexible cable. The flexible cable was fixed to the polypropylene film to prevent changes in capacitance due to movement.

[0076] An aluminum plate 82, which is a conductor, was used in place of human skin. A urethane tube (diameter 4 mm, spring constant 2.4 N / mm) was placed on top of the aluminum plate 82 as a dummy tube 81, and the prototype sensor sheet 80 was then placed on top of it to fix the tube 81. The prototype sensor sheet 80 was attached to the aluminum plate 82 with double-sided adhesive tape. When evaluating the prototype sensor sheet 80, a predetermined tensile stress was continuously applied to the dummy tube 81 (30 mm / min), and the behavior of the measured capacitance was observed. In addition, the tensile stress was applied in two directions: a direction perpendicular to the surface of the aluminum plate 82 (prototype sensor sheet 80) (z direction) and a direction parallel to it (x direction), and observations were made in these directions.

[0077] The microcontroller used to acquire the touch sensor values ​​was the CY8C5888LTI-LP097 (manufactured by Infineon Technologies), and the sensor values ​​were acquired using the internal function CAPSENSE (registered trademark). CAPSENSE sends a square wave to the capacitor formed by electrode 2 and calculates the capacitance value from the amount of charge (charge) that is charged and discharged. The integrated value of the current amount has a positive correlation with the capacitance, and the microcontroller outputs a pulse count corresponding to the integrated current value.

[0078] The GND potential of the microcomputer was connected to the aluminum plate 82. The microcomputer was connected to a PC (personal computer) via a wired connection. Using MATLAB (registered trademark) on the PC, the position of the sensor (electrode 2) and the capacitance measurement results were displayed for observation by the positions and colors of circles arranged in six columns and five rows corresponding to the two-dimensional arrangement of the electrodes 2. The electrode 2 contacted the aluminum plate 82 via the polypropylene film and double-sided adhesive tape, that is, the part of the electrode 2 where the double-sided adhesive tape was in contact with the aluminum plate 82, was displayed in green (white in the figure), and the other part of the electrode 2 was displayed in red (gray in the figure; the same applies below).

[0079] (Results due to tension in the z direction) Fig. 9(a) shows the initial state in which a dummy tube 81, set as a dummy medical instrument, is fixed to an aluminum plate 82 using a prototype sensor sheet 80. Fig. 9(b) is an example of a display in MATLAB of the measurement results of the capacitance distribution by the prototype sensor sheet 81 in the initial state.

[0080] Fig. 10(a) shows the state in which the dummy tube 81 is pulled upward (z direction) and the prototype sensor sheet 80 peels off from the aluminum plate 82. Fig. 10(b) is an example of a display in MATLAB of the measurement results of the capacitance distribution by the prototype sensor sheet 81 in the peeled state.

[0081] 9(a) and 9(b), the dummy tube 81 is attached so that it passes through the center of the prototype sensor sheet 80. It can be seen that in the initial state, peeling is detected not only in the central part of the prototype sensor sheet 80 but also in the area adjacent to it. This result is thought to be because the installation of the dummy tube 81 caused the prototype sensor sheet 80 to swell, resulting in peeling from the aluminum plate 82.

[0082] Furthermore, in the state where peeling has occurred as shown in Figures 10(a) and (b), it can be seen that peeling begins at the end of the prototype sensor sheet 80 on the side where a tensile load is applied to the dummy tube 81, and the peeled area increases.

[0083] (Results due to tension in the x direction) Fig. 11(a) shows the initial state in which a dummy tube 81, set as a dummy medical instrument, is fixed to an aluminum plate 82 using a prototype sensor sheet 80. Fig. 11(b) is an example of a display in MATLAB of the measurement results of capacitance distribution using the prototype sensor sheet 81 in the initial state.

[0084] Fig. 12(a) shows the state in which the prototype sensor sheet 80 peels off from the aluminum plate 82 when the dummy tube 81 is moved in the direction along the surface of the prototype sensor sheet 80 (x direction). Fig. 12(b) is an example of a display in MATLAB of the measurement results of the capacitance distribution by the prototype sensor sheet 81 in the peeled state.

[0085] According to the evaluation results of the tension along the surface direction of the prototype sensor sheet 80 in Figure 12(b), it can be seen that peeling of the prototype sensor sheet 80 occurs in response to the movement of the dummy tube 81, and that this peeling can be reliably detected. [Industrial Applicability]

[0086] Medical devices such as catheters and tubes placed on the skin surface of living bodies come in a wide variety of applications and sizes and are used in a wide range of medical settings. The self-removal prevention system of the present invention can be used appropriately for applications in the settings where such medical devices are used. For example, the data processing device that detects signs of removal in this system is highly scalable to multiple channels and large scale, allowing for flexible use in a variety of applications. Furthermore, for example, when applied to medical devices with different shapes, the system can be used by changing the arrangement and configuration of the sensor electrodes in the sensor sheet.

[0087] The self-removal prevention system of the present invention can be automatically calibrated using measurements taken at the start of operation, making it easy to use regardless of the method or position of attachment of the sensor sheet at the site of use, and can be used flexibly in emergency medical fields. The self-removal prevention system of the present invention can also be used to detect and prevent the removal of medical sheets that protect implantable medical devices inside the body. [Explanation of symbols]

[0088] 1 Self-removal prevention system 1A Self-removal detection device 10 Sensor sheet 2 electrodes 20 Data processing device (data acquisition unit 20A, control unit 20B) 23 Transmitting and receiving equipment 3. Insulating substrate 30 Alarm means 4 Protective sheet for fixing 9 Medical equipment 9a tube 99 Skin surface

Claims

1. A self-removal detection device that detects unplanned removal of a medical instrument placed along the skin surface of a living body, comprising: a deformable sheet-like sensor sheet that is placed on the outer surface of the skin surface with at least a part of the medical device placed on the skin surface in between, and has a plurality of individual electrodes that are two-dimensionally distributed to measure capacitance between the skin surface and the sensor sheet; a data processing device that acquires measurement data from the electrodes of the sensor sheet and obtains time-series data of a capacitance distribution corresponding to a distribution of the electrodes from the measurement data; The data processing device is characterized in that it detects signs of the medical device being removed from the skin surface or the result of removal based on temporal variations in the capacitance distribution from the initial state in which the medical device is placed on the skin surface.

2. The self-removal detection device according to claim 1, characterized in that the sensor sheet is integrated with a protective fixation sheet that fixes the medical instrument to the skin surface, and / or is used in combination with a medical sheet that fixes the medical instrument to the skin surface.

3. 2. The self-removal detection device according to claim 1, wherein the data processing device detects the sign or removal result using a result of learning the temporal variation of the capacitance distribution for a series of states regarding the attachment state of the medical device on the skin surface from the initial state to the end of use of the medical device.

4. The self-removal detection device according to claim 3, characterized in that the data processing device records or outputs for recording the time series data of the capacitance distribution, or in addition to the time series data of the capacitance distribution, data related to the surrounding environment in which the living body is located throughout a series of states from the initial state to the end of use of the medical instrument, together with time data.

5. The self-removal detection device according to claim 1, characterized in that the sensor sheet is configured to enable cutting to remove unnecessary electrodes from the two-dimensionally distributed electrodes, or cutting to fit a shape suitable for fixing the medical instrument.

6. The sensor sheet is used in the self-removal detection device according to any one of claims 1 to 5.

7. 6. The data processing device, which is used in the self-removal detection device according to claim 1.

8. The self-removal detection device according to any one of claims 1 to 5, an alarm means for notifying an external device of the self-removal detection device that the data processing device has detected the sign of removal or the result of removal; A self-removal prevention system comprising:

Images