Patent Publication Number: US-2021169580-A1

Title: Medical tube position confirmation system

Description:
TECHNICAL FIELD 
     The present invention relates to a medical tube position confirmation system. 
     BACKGROUND ART 
     Conventionally, in a medical setting, food is supplied directly into the stomach of a patient who finds oral ingestion of food difficult using a method known as nasal tube feeding. More specifically, a soft nasal tube is inserted through the nasal cavity of the patient until a tip end portion thereof reaches the stomach, whereupon liquid food and nutritional supplements are injected through a base end portion of the tube. 
     During nasal tube feeding, a method of inserting a nasal tube coated with lubricating jelly into the nostril, having the patient perform a swallowing action repeatedly while feeding the tip end portion of the tube more deeply little by little, and guiding the tip end portion of the nasal tube toward the esophagus side until the tip end portion reaches the stomach is implemented. 
     However, the back of the throat of a human bifurcates into two passages, namely the trachea and the esophagus, making the operation to insert the nasal tube extremely difficult, and when food or the like enters the lungs mistakenly, aspiration pneumonia or the like may occur. It is therefore necessary to perform an operation to confirm that the tip end portion of the nasal tube has reached the stomach. 
     Patent Document 1 discloses a detection line having a pair of insulated wires and a sensor portion formed on the tip end thereof. The detection line is inserted into a medical tube so that when the sensor portion comes into contact with gastric juice, a resistance value between the pair of insulated wires varies. Hence, by detecting variation in the resistance value between the pair of insulated wires, it can be determined that the sensor portion has come into contact with gastric juice and accordingly that the medical tube has correctly reached the stomach. 
     Further, Patent Document 2 discloses a nasal tube tip end position confirmation device including a casing, a connecting portion that communicates with the outside from the casing and is connected to a base end side of a nasal tube inserted into the body of a patient, a sensor element disposed in the casing, an electronic circuit, and display means. The electronic circuit outputs air pressure variation received by the sensor element in the form of an electric signal, and the display means receives the output from the electronic circuit and displays the air pressure variation in a recognizable state. Hence, by pressing the abdomen of the patient from the outside, air pressure variation is generated in the stomach, and by having the display means display information indicating that the sensor element has received the air pressure variation, it is possible to determine whether or not the nasal tube has been inserted to an appropriate position. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: Patent Publication JP-A-2016-77450 
     Patent Document 2: Japanese Patent No. 6245870 
     SUMMARY 
     Technical Problem 
     However, with a method employing a detection line, such as that of Patent Document 1, it is necessary for gastric juice to be secreted in an appropriate location. This means that the types of patients to which the method can be applied are limited, and runs counter to the aim of determining the position of the medical tube with precision. Further, with a method employing air pressure variation, such as that of Patent Document 2, a complicated configuration is required to control the air pressure, leading to an increase in manufacturing cost. 
     An object of the present invention is therefore to provide a medical tube position confirmation system with which the position of a medical tube can be confirmed more easily. 
     Solution to Problem 
     A medical tube position confirmation system according to an aspect of the present invention is a medical tube position confirmation system for confirming the position of a medical tube that is used to supply nutrients to the interior of a body by means of tube feeding while an end portion thereof is inserted into (placed in) the stomach. The system includes a light guide that is configured to guide light entering through an incident end portion so that the light exits through an exit end portion and is inserted into the medical tube so that the exit end portion is disposed in the interior of the stomach, and a light source that is optically connected to the incident end portion of the light guide and emits light containing wavelengths that pass through a living body. 
     According to this aspect, the light emitted from the light source, which contains wavelengths that pass through a living body, is guided through the interior of the light guide inserted into the medical tube so as to exit through the exit end portion of the light guide, which is disposed in the stomach. Having exited through the exit end portion, the light then passes through the stomach and the living body. Hence, an operator can confirm the position of the medical tube by checking the position in which the light passes through the stomach and the living body from the exterior of the living body. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to provide a medical tube position confirmation system with which the position of a medical tube can be confirmed more easily. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a pattern diagram showing an example of a configuration of a medical tube position confirmation system  1  according to an embodiment of the present invention. 
         FIG. 2  is a schematic view showing an example of a functional configuration of a light  10 . 
         FIG. 3  is a view illustrating wavelengths of light emitted by the light  10 . 
         FIG. 4  is a schematic view showing an example of a functional configuration of a camera  30 . 
         FIG. 5  is a schematic view showing an example of a functional configuration of a user terminal  40 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Referring to the attached figures, a preferred embodiment of the present invention will be described (note that in the figures, identical reference numerals denote identical or similar configurations). 
     (1) Overall Configuration 
       FIG. 1  is a pattern diagram showing an example of a configuration of a medical tube position confirmation system  1  according to an embodiment of the present invention. As shown in  FIG. 1 , the medical tube position confirmation system  1  includes, for example, a light  10 , an optical fiber  20 , a camera  30 , a user terminal  40 , and a database  50 . The user terminal  40  is connected communicably to each of the light  10 , the camera  30 , and the database  50  via a communication network. 
     (2) Configurations of Respective Parts 
     (2-1) Light  10   
       FIG. 2  is a schematic view showing an example of a functional configuration of the light  10 . The light  10  is an example of a light source that emits light containing wavelengths that pass through a living body. The light  10  is formed by providing a light-emitting unit  11 , a drive circuit  12 , a processing unit  13 , a storage unit  14 , and a communication unit  15  in a substantially cylindrical casing formed from metal, resin, or the like, for example. 
     The light-emitting unit  11  is constituted by a light-emitting LED, for example, and emits light containing wavelengths that pass through a living body. When the light  10  receives a supply of electric energy from a power supply (not shown) via the drive circuit  12  while a switch (not shown) provided on the light  10  is switched ON, the light  10  emits light of predetermined wavelengths by converting the electric energy into optical energy. Note that the light-emitting unit  11  is not limited to a light-emitting LED and may be any light-emitting body that emits light containing a wavelength that passes through a living body. 
     The light  10  is optically connected to an incident end portion  20 I of the optical fiber  20 , to be described below, so that the light emitted by the light-emitting unit  11  of the light  10  enters the incident end portion  20 I of the optical fiber  20 . 
     The processing unit  13  is a CPU or the like, for example, having one or a plurality of processors and corresponding peripheral circuits, and performs overall control of the entire operation of the light  10  on the basis of a program or the like stored in the storage unit  14 . 
     The storage unit  14  is constituted by a nonvolatile memory or the like, such as an EEPROM (Electronically Erasable and Programmable Read Only Memory), for example, and stores preset control information and the like relating to the light  10 . 
     The communication unit  15  includes a communication interface circuit for connecting the light  10  to the communication network, and communicates with the communication network. Note that the light  10  may have a simpler configuration not including the communication unit  15  and so on. 
     Here, using  FIG. 3 , the wavelengths of the light emitted by the light  10  will be described.  FIG. 3  shows the light absorption coefficient of each of oxyhemoglobin, reduced hemoglobin, melanin, and water, which are the main constituent elements of a living body. On the graph in  FIG. 3 , the horizontal axis shows the wavelength (nm) and the vertical axis shows the absorption coefficient. 
     As shown in  FIG. 3 , absorption by blood (in other words, hemoglobin) is high in a wavelength region at or below approximately 650 nm, while absorption by water is high in a wavelength region exceeding approximately 950 nm. In a wavelength region of no less than approximately 650 nm and no more than approximately 950 nm, meanwhile, the respective absorption coefficients of hemoglobin and water are comparatively low. It can therefore be said that light in this wavelength region (no less than approximately 650 nm and no more than approximately 950 nm) passes through a living body more easily than light in another wavelength region. 
     There are no particular limitations on the wavelengths of the light emitted by the light-emitting unit  11  of the light  10  as long as wavelengths that pass through a living body are included therein, but as noted above, the wavelengths preferably include wavelengths within a range of no less than approximately 650 nm and no more than approximately 950 nm. 
     Further, as shown in  FIG. 3 , the absorption rate of oxyhemoglobin is particularly low in a wavelength region of no less than approximately 650 nm and no more than approximately 800 nm. Therefore, the wavelengths of the light emitted by the light-emitting unit  11  of the light  10  preferably include at least a part of a wavelength region of no less than approximately 650 nm and no more than approximately 800 nm. 
     Furthermore, as shown in  FIG. 3 , the absorption rate of reduced hemoglobin is particularly low in a wavelength range of no less than approximately 800 nm and no more than approximately 950 nm. Therefore, the wavelengths of the light emitted by the light-emitting unit  11  of the light  10  preferably include at least a part of a wavelength region of no less than approximately 800 nm and no more than approximately 950 nm. 
     Moreover, as shown in  FIG. 3 , the absorption rate of water is particularly low in a wavelength range of no less than approximately 650 nm and no more than approximately 700 nm. Therefore, the wavelengths of the light emitted by the light-emitting unit  11  of the light  10  preferably include at least a part of a wavelength region of no less than approximately 650 nm and no more than approximately 700 nm. 
     (2-2) Optical Fiber  20   
     The optical fiber  20  is an example of a light guide that takes the shape of a narrow, flexible fiber, for example, and can be inserted into the interior of a medical tube T, as shown in  FIG. 1 . The optical fiber  20  has a two-layer structure constituted by, for example, a central core (not shown) formed from silica glass, plastic, or the like, and cladding (not shown) covering the periphery of the central core. 
     As shown in  FIG. 1 , the incident end portion  20 I through which the light emitted by the light  10  and so on enters is formed on one end of the optical fiber  20 . The incident end portion  20 I is positioned so as to be optically connectable to the light  10  in a state where the optical fiber  20  is inserted into the interior of the medical tube T. 
     Further, as shown in  FIG. 1 , an exit end portion  20 E through which the light exits is formed on the other end of the optical fiber  20 . When the optical fiber  20  correctly reaches the stomach while inserted into the interior of the medical tube T, the exit end portion  20 E is disposed inside the stomach (indicated by a reference symbol S in  FIG. 1 ). 
     The refractive index of the core of the optical fiber  20  is set to be higher than the refractive index of the cladding of the optical fiber  20 . Accordingly, the light entering through the incident end portion  20 I is totally reflected on the boundary between the core and the cladding so as to propagate through the core. Having propagated through the core and reached the exit end portion  20 E, the light exits through the exit end portion  20 E. Having exited through the exit end portion  20 E, the light passes through the stomach and other body parts and exits the living body so as to partially reach the camera  30 . 
     (2-3) Camera  30   
       FIG. 4  is a schematic view showing an example of a functional configuration of the camera  30 . 
     The camera  30  is an example of an imaging unit that generates image data by capturing an image of the living body (including a part of the living body) on the basis of at least the light that passes through the living body after exiting through the exit end portion  20 E of the optical fiber  20 . The camera  30  includes, for example, an image sensor  31 , a processing unit  32 , a storage unit  33 , and a communication unit  34 . The camera  30  may be a camera that is particularly sensitive to infrared rays, for example. 
     The image sensor  31  is constituted by a CCD (a Charge Coupled Device), a CMOS (a Complementary Metal Oxide Semiconductor), or the like, for example, and under the control of the processing unit  32 , the image sensor  31  detects light that has been condensed by a lens, not shown in the figure, and converts the light into an electric signal. 
     The processing unit  32  is a CPU or the like, for example, having one or a plurality of processors and corresponding peripheral circuits, and performs overall control of the entire operation of the information processing device on the basis of a program or the like stored in the storage unit  33 . The processing unit  32  generates image data on the basis of the electric signal generated by the image sensor  31 , for example. Further, the processing unit  32  transmits the generated image data to the user terminal  40  or the database  50  via the communication unit  34 . 
     The storage unit  33  includes at least one of a magnetic tape device, a magnetic disk device, and an optical disk device, for example, and stores a computer program, data, and so on used in the processing executed by the processing unit. The storage unit  33  is an example of an image data storage unit for storing the image data generated when the camera  30  captures an image of the living body. 
     The communication unit  34  includes a communication interface circuit for connecting the camera  30  to the communication network, and communicates with the communication network. 
     Note that the camera  30  may also include a display unit (not shown) for displaying the image data generated by the processing unit  32  and so on. 
     (2-4) User Terminal  40   
       FIG. 5  is a schematic view showing an example of a functional configuration of the user terminal  40 . The user terminal  40  may be any general-purpose information processing terminal and includes, for example, a communication unit  41 , a storage unit  42 , a processing unit  43 , an operation unit  44 , a display unit  45 , and so on. 
     The communication unit  41  includes a communication interface circuit for connecting the user terminal  40  to the communication network, and communicates with the communication network. 
     The storage unit  42  includes at least one of a magnetic tape device, a magnetic disk device, and an optical disk device, for example, and stores a computer program, data, and so on used in the processing executed by the processing unit. The storage unit  42  is an example of the image data storage unit for storing the image data generated when the camera  30  captures an image of the living body. 
     The processing unit  43  is a CPU or the like, for example, having one or a plurality of processors and corresponding peripheral circuits, and performs overall control of the entire operation of the information processing device on the basis of a program or the like stored in the storage unit. The processing unit  43  may determine whether or not the position of the medical tube T is appropriate by analyzing image data received from the camera  30  over the communication network. Further, the processing unit  13  may transmit the image data received from the camera  30  over the communication network to the database  50 , for example. Furthermore, the processing unit  13  may transmit a control signal for switching the switch of the light  10  ON and OFF to the light  10 , for example. 
     The operation unit  44  is constituted by a touch panel, key buttons, or the like, for example, and serves to receive operations performed by a user to input alphabetic characters, numerals, symbols, and so on and supply signals corresponding to the operations to the processing unit. 
     The display unit  45  is constituted by a liquid crystal display, an organic EL (Electro-Luminescence) display, or the like, for example, and displays images based on display data supplied from the processing unit and so on. 
     (2-5) Database  50   
     The database  50  is a database managed by a medical institution such as a hospital, for example, and includes at least one of a magnetic tape device, a magnetic disk device, and an optical disk device. The database  50  receives image data from the camera  30  or the user terminal  40 , for example, and stores the received image data. In other words, the database  50  is an example of the image data storage unit for storing the image data generated when the camera  30  captures an image of the living body. The database  50  may be connected to an external information processing device, such as a management server used by a medical institution or the like, for example, via a communication network. The external information processing device may obtain the image data stored in the database  50  and execute processing corresponding to various aims on the image data. 
     (3) Use Method and Operation 
     Next, a use method and an operation of the medical tube position confirmation system  1  will be described. 
     First, an operator checks the end portion of the medical tube T in the nasal cavity or the like of the patient and then inserts the optical fiber  20  into the interior of the medical tube T by a predetermined length, starting with the exit end portion  20 E. 
     Next, the switch (not shown) provided on the light  10  is switched ON so that the light  10  emits light. At this time, the operator may cause the light  10  to emit light by operating the switch of the light  10 , for example. Alternatively, the operator may cause the light  10  to emit light by operating the user terminal  40  so that a control signal for switching the switch of the light  10  ON is transmitted from the user terminal  40  to the light  10 . 
     When the light  10  emits light, the light emitted by the light  10  enters the incident end portion  20 I of the optical fiber  20 . The light that enters the incident end portion  20 I propagates through the interior of the optical fiber  20  by total reflection so as to reach the exit end portion  20 E. Having reached the exit end portion  20 E, the light exits through the exit end portion  20 E and passes through the body of the patient. 
     The operator then checks the position of the light passing through the body of the patient in order to determine whether or not the position of the light is a position corresponding to the stomach. When the position of the light is a position corresponding to the stomach, it can be determined that the medical tube T has reaches the stomach appropriately. When the position of the light is not a position corresponding to the stomach or when the presence of the light cannot be confirmed, it can be determined that the medical tube T has not reached the stomach. Here, the position of the light may be checked using either a method of visual confirmation by the operator or a method employing the image data generated by the camera  30 . In the method employing the image data generated by the camera  30 , for example, the user terminal  40  receives from the camera  30  the image data generated by the camera  30  on the basis of at least the light passing through the stomach and other body parts. The user terminal  40  then analyzes the image data to determine whether or not the position of the light is a position corresponding to the stomach. 
     (4) Miscellaneous 
     Note that generally, the optical intensity required for light to pass from the interior of the stomach to the exterior of the body is lower than the optical intensity required for light to pass from the interior of the lungs and trachea to the exterior of the body. Therefore, the light source, such as the light  10 , may be set to emit light at an intensity that equals or exceeds a first intensity required for light to pass from the interior of the stomach to the exterior of the body but is lower than a second intensity required for light to pass from the interior of the lungs and trachea to the exterior of the body. According to this configuration, there is no need to determine the position of the stomach during visual confirmation of the light by the operator or analysis of the image data, and it can be determined that the medical tube T has appropriately reached the stomach simply by determining whether or not the light can be confirmed. 
     The embodiment described above is to be used to facilitate understanding of the present invention, and the present invention is not limited thereto. The elements included in the embodiment, as well as the arrangements, materials, conditions, shapes, sizes, and so on thereof, are not limited to the cited examples and may be modified as appropriate. Moreover, configurations illustrated in different embodiments may be partially replaced or combined. 
     REFERENCE SIGNS LIST 
     
         
           1  Medical tube position confirmation system 
           10  Light 
           11  Light-emitting unit 
           12  Drive circuit 
           13  Processing unit 
           14  Storage unit 
           15  Communication unit 
           20  Optical fiber 
           20 I Incident end portion 
           20 E Exit end portion 
           30  Camera 
           31  Image sensor 
           32  Processing unit 
           33  Storage unit 
           34  Communication unit 
           40  User terminal 
           41  Communication unit 
           42  Storage unit 
           43  Processing unit 
           44  Operation unit 
           45  Display unit