Patent Description:
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.

<CIT> 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, <CIT> 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.

<CIT> discloses a tube distal end position confirmation device capable of confirming a distal end position of a tube for supplying liquid substance, such as glucose liquid, to an inside the body or deriving blood. <CIT> refers to a light-emitting optical fiber with worked tip end and in-body illumination device using same. <CIT> discloses a feeding tube assembly with a light element attachable thereto.

However, with a method employing a detection line, such as that <CIT>, 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 <CIT>, 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.

The object of the invention is defined by the appended claims <NUM>-<NUM>. A medical tube position confirmation system according to an aspect of the 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, a light source for emitting light including a wavelength passing through a living body, the light source being optically connected to the incident end of the light guide so that the light enters the light guide, and optionally a scattering part optically connected to the light guide on the exit end portion of the light guide so as to scatter light emitted by the light guide.

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, and to be scattered extensively by the scattering portion. Since the emitted light is scattered extensively, an operator can
easily confirm the light which has passed through the stomach and the living body, which makes it easier to confirm the position of the medical tube.

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.

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).

<FIG> is a pattern diagram showing an example of a configuration of a medical tube position confirmation system <NUM> according to an embodiment of the present invention. As shown in <FIG>, the medical tube position confirmation system <NUM> includes, for example, a light <NUM>, an optical fiber <NUM>, a camera <NUM>, a user terminal <NUM>, and a database <NUM>. The user terminal <NUM> is connected communicably to each of the light <NUM>, the camera <NUM>, and the database <NUM> via a communication network.

<FIG> is a schematic view showing an example of a functional configuration of the light <NUM>. The light <NUM> is an example of a light source that emits light containing wavelengths that pass through a living body. The light <NUM> is formed by providing a light-emitting unit <NUM>, a drive circuit <NUM>, a processing unit <NUM>, a storage unit <NUM>, and a communication unit <NUM> in a substantially cylindrical casing formed from metal, resin, or the like, for example.

The light-emitting unit <NUM> is constituted by a light-emitting LED, for example, and emits light containing wavelengths that pass through a living body. When the light <NUM> receives a supply of electric energy from a power supply (not shown) via the drive circuit <NUM> while a switch (not shown) provided on the light <NUM> is switched ON, the light <NUM> emits light of predetermined wavelengths by converting the electric energy into optical energy. Note that the light-emitting unit <NUM> 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 <NUM> is optically connected to an incident end portion 20I of the optical fiber <NUM>, to be described below, so that the light emitted by the light-emitting unit <NUM> of the light <NUM> enters the incident end portion 20I of the optical fiber <NUM>.

The processing unit <NUM> 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 <NUM> based on a program or the like stored in the storage unit <NUM>.

The storage unit <NUM> 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 <NUM>.

The communication unit <NUM> includes a communication interface circuit for connecting the light <NUM> to the communication network, and communicates with the communication network. Note that the light <NUM> may have a simpler configuration not including the communication unit <NUM> and so on.

Here, using <FIG>, the wavelengths of the light emitted by the light <NUM> will be described. <FIG> 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>, the horizontal axis shows the wavelength (nm) and the vertical axis shows the absorption coefficient.

As shown in <FIG>, absorption by blood (in other words, hemoglobin) is high in a wavelength region at or below approximately <NUM>, while absorption by water is high in a wavelength region exceeding approximately <NUM>. In a wavelength region of no less than approximately <NUM> and no more than approximately <NUM>, 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 <NUM> and no more than approximately <NUM>) 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 <NUM> of the light <NUM> 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 <NUM> and no more than approximately <NUM>.

Further, as shown in <FIG>, the absorption rate of oxyhemoglobin is particularly low in a wavelength region of no less than approximately <NUM> and no more than approximately <NUM>. Therefore, the wavelengths of the light emitted by the light-emitting unit <NUM> of the light <NUM> preferably include at least a part of a wavelength region of no less than approximately <NUM> and no more than approximately <NUM>.

Furthermore, as shown in <FIG>, the absorption rate of reduced hemoglobin is particularly low in a wavelength range of no less than approximately <NUM> and no more than approximately <NUM>. Therefore, the wavelengths of the light emitted by the light-emitting unit <NUM> of the light <NUM> preferably include at least a part of a wavelength region of no less than approximately <NUM> and no more than approximately <NUM>.

Moreover, as shown in <FIG>, the absorption rate of water is particularly low in a wavelength range of no less than approximately <NUM> and no more than approximately <NUM>. Therefore, the wavelengths of the light emitted by the light-emitting unit <NUM> of the light <NUM> preferably include at least a part of a wavelength region of no less than approximately <NUM> and no more than approximately <NUM>.

The optical fiber <NUM> 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>. The optical fiber <NUM> 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>, the incident end portion 20I through which the light emitted by the light <NUM> and so on enters is formed on one end of the optical fiber <NUM>. The incident end portion 20I is positioned so as to be optically connectable to the light <NUM> in a state where the optical fiber <NUM> is inserted into the interior of the medical tube T. The refractive index of the core of the optical fiber <NUM> is set to be higher than that of the cladding of the optical fiber <NUM>. Therefore, the light entering from the incident end 20I propagates inside the optical fiber <NUM> while undergoing total reflection at the boundary of the core and cladding.

As shown in <FIG>, an exit end portion 20E through which the light exits is formed on the other end of the optical fiber <NUM>. When the optical fiber <NUM> correctly reaches the stomach while inserted into the interior of the medical tube T, the exit end portion 20E is disposed inside the stomach (indicated by a reference symbol S in <FIG>).

Here, referring to <FIG>, the configuration of the exit end portion 20E side of the optical fiber <NUM> will be explained. As shown in <FIG>, a scattering portion <NUM> is optically connected to the exit end portion 20E of the optical fiber <NUM>. The scattering portion <NUM> is composed of, for example, a light transmissive resin having a cylindrical shape containing a predetermined scattering material. The light that propagates through the core of the optical fiber <NUM> and reaches the exit end portion 20E is scattered in various directions by the scattering portion <NUM> after being emitted from the exit end portion 20E. The scattered light passes through the stomach and other body parts and exits the living body so as to partially reach the camera <NUM>.

As a predetermined scattering material contained by the scattering portion <NUM>, for example, a scattering material having the property that the degree of scattering against light is greater for light with a shorter wavelength is suitably used. The predetermined scattering material may be, for example, a fluorescent pigment. The scattering portion <NUM> may contain a plurality of types of scattering materials. The content rate of the scattering material of the scattering portion <NUM> may be uniform throughout the scattering portion <NUM>. Alternatively, the content rate of the scattering material in the scattering portion <NUM> may be non-uniform throughout the scattering portion <NUM>. For example, the content rate of the scattering material of the scattering portion <NUM> may be distributed with a predetermined gradient along the optical axis L or other directions, or may differ between the optical fiber <NUM> side and the other side of the optical fiber <NUM>.

The protective portion <NUM> is composed of, for example, a light transmissive resin or synthetic quartz glass, etc., which presents a substantially cylindrical shape having a through hole along the axial direction. The protective portion <NUM> protects at least a part of the optical fiber <NUM> and at least a part of the scattering portion <NUM> along the optical axis L (see <FIG>). The light scattered by the scattering portion <NUM> passes through the protective portion <NUM>.

Here, referring to <FIG>, the dimensions of the scattering portion <NUM> will be explained. <FIG> schematically shows the cross section according to the A-A' line in <FIG>. In <FIG>, the dotted arrow indicates the optical axis L of the optical fiber <NUM>. The dimension of the scattering portion <NUM> in the direction parallel to the optical axis L is H, and the dimension of the scattering portion <NUM> in the direction perpendicular to the optical axis L is W. As shown in <FIG>, the dimensions of the scattering portion <NUM> are set so that H is longer than W. As a result, the optical path with a smaller angular difference from the optical axis L generally has a longer distance to travel in the scattering portion <NUM>, and the probability of light being scattered by the scattering material contained in the scattering portion <NUM> becomes higher. Therefore, the light emitted from the optical fiber <NUM> spreads out and travels in directions other than the direction of the optical axis L.

<FIG> is a schematic view showing an example of a functional configuration of the camera <NUM>.

The camera <NUM> 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) based at least on the light that passes through the living body after being scattered by a scattering portion <NUM>. The camera <NUM> includes, for example, an image sensor <NUM>, a processing unit <NUM>, a storage unit <NUM>, and a communication unit <NUM>. The camera <NUM> may be an infrared sensor or an infrared camera that particularly has a high capability of sensing infrared rays, for example.

The image sensor <NUM> 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 <NUM>, the image sensor <NUM> 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 <NUM> 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 based on a program or the like stored in the storage unit <NUM>. The processing unit <NUM> generates image data based on the electric signal generated by the image sensor <NUM>, for example. Further, the processing unit <NUM> transmits the generated image data to the user terminal <NUM> or the database <NUM> via the communication unit <NUM>.

The storage unit <NUM> 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 <NUM> is an example of an image data storage unit for storing the image data generated when the camera <NUM> captures an image of the living body.

The communication unit <NUM> includes a communication interface circuit for connecting the camera <NUM> to the communication network, and communicates with the communication network.

Note that the camera <NUM> may also include a display unit (not shown) for displaying the image data generated by the processing unit <NUM> and so on.

<FIG> is a schematic view showing an example of a functional configuration of the user terminal <NUM>. The user terminal <NUM> may be any general-purpose information processing terminal and includes, for example, a communication unit <NUM>, a storage unit <NUM>, a processing unit <NUM>, an operation unit <NUM>, a display unit <NUM>, and so on.

The communication unit <NUM> includes a communication interface circuit for connecting the user terminal <NUM> to the communication network, and communicates with the communication network.

The storage unit <NUM> 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 <NUM> is an example of the image data storage unit for storing the image data generated when the camera <NUM> captures an image of the living body.

The processing unit <NUM> 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 based on a program or the like stored in the storage unit. The processing unit <NUM> may determine whether or not the position of the medical tube T is appropriate by analyzing image data received from the camera <NUM> over the communication network. Further, the processing unit <NUM> may transmit the image data received from the camera <NUM> over the communication network to the database <NUM>, for example. Furthermore, the processing unit <NUM> may transmit a control signal for switching the switch of the light <NUM> ON and OFF to the light <NUM>, for example.

The operation unit <NUM> 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 <NUM> 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.

The database <NUM> 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 <NUM> receives image data from the camera <NUM> or the user terminal <NUM>, for example, and stores the received image data. In other words, the database <NUM> is an example of the image data storage unit for storing the image data generated when the camera <NUM> captures an image of the living body. The database <NUM> 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 <NUM> and execute processing corresponding to various aims on the image data.

Next, a use method and an operation of the medical tube position confirmation system <NUM> 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 <NUM> into the interior of the medical tube T by a predetermined length, starting with the exit end portion 20E which is optically connected with a scattering portion <NUM>.

Next, the switch (not shown) provided on the light <NUM> is switched ON so that the light <NUM> emits light. At this time, the operator may cause the light <NUM> to emit light by operating the switch of the light <NUM>, for example. Alternatively, the operator may cause the light <NUM> to emit light by operating the user terminal <NUM> so that a control signal for switching the switch of the light <NUM> ON is transmitted from the user terminal <NUM> to the light <NUM>.

When the light <NUM> emits light, the light emitted by the light <NUM> enters the incident end portion 20I of the optical fiber <NUM>. The light that enters the incident end portion 20I propagates through the interior of the optical fiber <NUM> by total reflection so as to reach the exit end portion 20E. Having reached the exit end portion 20E, the light exits through the exit end portion 20E and then is scattered by a scattering portion <NUM>, and a part of the light 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 <NUM>. In the method employing the image data generated by the camera <NUM>, for example, the user terminal <NUM> receives from the camera <NUM> the image data generated by the camera <NUM> based at least on the light passing through the stomach and other body parts. The user terminal <NUM> then analyzes the image data to determine whether or not the position of the light is a position corresponding to the stomach.

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 <NUM>, 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.

<FIG> illustrates another scattering portion <NUM>. <FIG> is a cross-sectional view similar to that of <FIG> described above. As shown in <FIG>, a scattering portion <NUM> is coupled to the emit end portion 20E of the optical fiber <NUM> by an adhesive resin <NUM>. The scattering portion <NUM> has a substantially conical shape formed from an apex 60T (protruded portion), a side surface 60R, and a bottom surface 60B. The apex 60T of the scattering portion <NUM> faces the optical fiber <NUM>. The side surface 60R of the scattering portion <NUM> has a mirror surface formed, for example, by aluminum vapor deposition. The bottom surface 60B of the scattering portion <NUM> faces the opposite side of the optical fiber <NUM>.

As shown by the solid arrows in <FIG>, when the light propagating in the optical fiber <NUM> and emitted from the exit end portion 20E reaches the side surface 60R of the scattering portion <NUM>, it is reflected by the side surface 60R. By adjusting the angle θ formed between the optical axis L and the side surface 60R of the scattering portion <NUM>, the direction of the reflected light can be adjusted. The value of the angle θ is not particularly limited, but approximately <NUM> degrees is preferred.

The shape of the scattering portion <NUM> described above is an example, and the scattering portion <NUM> may present any shape as long as a reflective surface is formed to reflect the light propagating in the optical fiber <NUM> and emitted from the exit end portion 20E. The shape of the bottom surface of the scattering portion <NUM> (the surface provided on the opposite side of the optical fiber <NUM>) is not particularly limited, but may include, for example, an ellipse, a polygon (including polygons in which the length of each side is not equal), or any other arbitrary shape in addition to a regular circle. These illustrated shapes may be abbreviated shapes that do not necessarily meet the geometric definition. The bottom surface of the scattering portion <NUM> may be shaped to cover only a part of the exit end portion 20E of the optical fiber <NUM> in a plane perpendicular to the optical axis L. As a result, a portion of the light emitted from the exit end portion 20E of the optical fiber <NUM> will travel toward the living body without being reflected by the scattering portion <NUM>. By adjusting the size of the bottom surface of the scattering portion <NUM>, it is possible to adjust the distribution of the light traveling direction.

As described above, the side surface 60R of the scattering portion <NUM> presents an abbreviated linear shape in the cross-sectional view shown in <FIG> (cross-sectional view by a plane passing through the optical axis L) and has a predetermined gradient (θ) with respect to the optical axis L. However, the side surface of the scattering portion <NUM> may not present a straight line shape in the said cross-sectional view, and the gradient with respect to the optical axis L may vary depending on the position. Also, the side surface of the scattering portion <NUM> may have a mirror surface formed by a method other than aluminum vapor deposition. The side surface of the scattering portion <NUM> does not have to be a specular surface that reflects light, but may be, for example, a scattering surface that scatters light.

Claim 1:
A medical tube position confirmation system for confirming the position of a medical tube (T) 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 and/or placed in the stomach, the system comprising:
a light guide (<NUM>) that is configured to guide light entering through an incident end portion (20I) so that the light exits through an exit end portion (20E), and is configured to be insertable into the medical tube (T) so that the exit end portion (20E) is disposed in the interior of the stomach;
a light source (<NUM>) for emitting light including a wavelength passing through a living body, the light source (<NUM>) being optically connected to the incident end of the light guide (<NUM>) so that the light enters the light guide (<NUM>); and
a scattering part (<NUM>) optically connected to the light guide (<NUM>) on the exit end portion (20E) of the light guide (<NUM>) so as to scatter light emitted by the light guide (<NUM>),
characterized in that the light source (<NUM>) is 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.