Patent Publication Number: US-2011060209-A1

Title: Intracorporeal monitoring apparatus having flection

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-206095, filed on Sep. 7, 2009, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments of the present invention relate to an intracorporeal monitoring apparatus having a flection for ultrasonic diagnosis such as a transesophageal echocardiography probe, endoscope, and ultrasonic laparoscope. 
     BACKGROUND 
     A transesophageal echocardiography (TEE) probe is an ultrasonic probe to diagnose the heart through esophageal walls or stomach walls after being perorally inserted into the esophagus. The TEE probe includes a tip unit that transmits/receives an ultrasonic wave, a guiding unit to insert the TEE probe into the esophagus, a flection that connects the guiding unit and the tip unit and whose angle of bend is operable, an operation unit that operates the angle of bend of the flection, and a connector unit to connect the TEE probe to the body of ultrasonic diagnostic equipment. 
     The flection normally has, like an endoscope for a digestive organ, a plurality of metallic bending mechanisms linked by a link mechanism coated with an angle tube. Elasticity of the angle tube determines the degree of bendability of the flection. 
     Rubber material superior in durability and biocompatibility such as fluorubber and silicon rubber is generally used for the angle tube. To prevent an unintentional current from being passed to a patient from an external power supply, it is necessary for the guiding unit, the flection, and the tip unit that come into contact with the patient to adopt an F-type applied portion to be electrically floating. Thus, also the angle tube preferably has insulating properties. 
     A flection that can be bent as flexibly as possible is demanded for an endoscope for a digestive organ to improve operability thereof in the stomach or duodenum. On the other hand, a TEE probe does not normally have an optical system and thus, the laryngopharynx, esophagus, gastric mucosa and the like may be damaged depending on how the probe is inserted or operated. Therefore, flexing resistance properties that do not allow the flection to bend easily are demanded to prevent the tip unit from being abruptly bent when the TEE probe is inserted or operated. 
     There are mainly two methods to realize such flexing resistance properties. One method is to enhance flexing resistance properties of the flection itself by changing the elastic constant of the angle tube used for the flection. The other method is to attach a mechanism to a control knob that operates the flection so that the flection is not easily bent. 
     For the former method of improving flexing resistance properties by changing the elastic constant of the angle tube, rubber material that does not stretch much is selected and used from the start or the rubber is made thicker to be able to enhance the restoring force or repulsive force. 
     However, if the angle rubber of a TEE probe is made thicker, the rubber will not stretch so that the angle tube cannot be passed through the tip unit having a larger diameter than the guiding unit during assembly or repairs/replacement. Thus, depending on the stretch amount of the angle tube, the diameter of the tip unit may be limited. 
     Making the tip unit still smaller can reduce a physical burden of the patient during insertion because smooth movement of the tip unit is thereby enabled inside a body cavity, but there is a problem that image quality deteriorates due to a smaller aperture of ultrasonic transducers. Thus, to make replacement of the angle tube easier while giving the same elastic constant to the angle rubber, for example, a method of doubling the angle tube with half a thickness each to make each angle tube easier to stretch and replacement thereof easier can be considered. 
     Though not intended to make replacement of the angle tube easier, an example of doubling the angle tube in a flection is known in an endoscope for the purpose of detecting an occurrence of angle tube defects (see, for example, Japanese Patent Application Laid-Open No. 2005-211432). 
     The control knob can be made not to rotate easily by a friction mechanism or a rotary click mechanism as a mechanism that does not allow the flection to bend easily. However, a problem of long-term stability or a problem of causing the cost to rise due to more complex mechanisms may arise. 
     The angle tube may be bitten by the patient while being used, or fractured due to an external force while being handled or ageing. If the angle tube is fractured and a hole is cut, a problem of the inner mechanism being affected by a liquid breaking into the probe or of becoming a source of infection after bacteria being propagated in the hole may arise. 
     An endoscope disclosed by Japanese Patent Application Laid-Open No. 2005-211432 has a structure in which a gas can be infused into a space between rubber members of the double angle tubes so that a break in the angle tubes can easily be detected. 
     A TEE probe having no structure allowing a gas to infuse into, on the other hand, has a mechanism to detect presence/absence of a hole by soaking the tip unit in water in the inspection before the use to measure insulation between water around the tip unit and metal inside the probe. If the insulating angle tube is doubled in such a TEE probe, insulation properties are maintained even if a hole is cut in outer rubber so that an occurrence of the defect cannot be detected. Then, there is a danger of infection among patients after bacteria breaking into a space between the outer rubber and inner rubber from the hole in the outer rubber. 
     In the foregoing, only a TEE probe has been described, but an endoscope and an ultrasonic laparoscope also have a flection and similar problems also arise in each flection. 
     The present invention provides an intracorporeal monitoring apparatus having a flection in which an occurrence of defects in the angle tube can easily be detected and also the angle tube can easily be replaced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a transesophageal echocardiography probe according to an embodiment. 
         FIG. 2  is a diagram showing an internal structure of a flection of the transesophageal echocardiography probe according to an embodiment. 
         FIG. 3  is a diagram showing a sectional structure of the flection of the transesophageal echocardiography probe according to an embodiment. 
         FIG. 4  is a diagram illustrating an apparatus to inspect whether there is a hole in the flection in the present embodiment. 
         FIG. 5  is a perspective view showing the structure of an ultrasonic laparoscope in another embodiment. 
         FIG. 6  is a perspective view showing the structure of an endoscope in still another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment of the present invention, an intracorporeal monitoring apparatus having a flection, includes 
     a tip unit that receives an ultrasonic signal or light from inside a subject and converts the ultrasonic signal or light into an electric signal; 
     a guiding unit that transmits the electric signal obtained by the tip unit; and 
     a flection that is provided between the guiding unit and the tip unit, transmits the electric signal obtained by the tip unit to the guiding unit, and can be bent, the flection has a conductor that is curved and extensible, one or a plurality of layers of conductive tubes coating the conductor, and a layer of an insulating tube coating the conductive tubes. 
     According to an embodiment of the present invention, an occurrence of an angle tube defect can be detected so that an intracorporeal monitoring apparatus having a flection in which the angle tube can easily be replaced and flexing properties of the flection are improved can be obtained. 
     An embodiment of the present invention will be described in detail with reference to drawings.  FIG. 1  is a schematic view of a transesophageal echocardiography (TEE) probe according to an embodiment. The TEE probe includes a tip unit  11  that transmits/receives an ultrasonic wave into/from a subject, a guiding unit  12  used for insertion into the esophagus, and a flection  13  that connects the tip unit  11  and the guiding unit  12  and whose angle of bend is operable. 
     Though not illustrated, the TEE probe further includes an operation unit that can operate the angle of bend of the flection  13  and a connector unit to connect to the body of ultrasonic diagnostic equipment. The tip unit  11  contains ultrasonic transducers  14 , which transmit/receive an ultrasonic wave. The flection  13  has angle links described later coated with an angle tube therearound. 
       FIG. 2  is a diagram showing an internal structure of the flection of the TEE probe according to an embodiment of the present invention and the internal structure of the flection  13  is shown in such a way that the internal structure becomes evident by removing a portion of the angle tube from the state in  FIG. 1 .  FIG. 3  shows a sectional structure of the flection  13 . 
     As shown in  FIGS. 2 and 3 , the flection  13  has angle links  21  in an annular shape coated with two angle tubes  22  and  23  on an outer circumference thereof. The angle tube  22  on the inner side is electrically-conductive and the angle tube  23  on the outer side is insulating. 
     The flection  13  connects the guiding unit  12  and the tip unit  11  by a plurality of the angle links  21 . The angle links are axis-connected by a knot ring  24  of each and can rotate around the axis up to a fixed angle determined for each. By adopting such a configuration, the tip unit  11  can be arranged at an angle with respect to the guiding unit  12  while drawing a curve. Further, the knot ring  24  is also arranged at adjacent 90 degrees rotated positions and thus, the tip unit  11  can also be arranged at an angle with respect to a directional axis perpendicular to the axis. In this manner, the angle links constitute a conductor that is curved and extensible. 
     The angle tubes  22  and  23  are coated to cover the angle links  21 . Both ends of the angle tubes  22  and  23  are fixed to the guiding unit  12  and the tip unit  11  by fixtures  25   a  and  25   b  respectively. Accordingly, internal airtightness can be ensured to prevent a liquid such as a body fluid from penetrating into the mechanism. 
     Further, the angle tubes  22  and  23  have flexibility and thus, the flection  13  can be brought to a bent state accompanying a wire operation of the angle links  21 . Common technology of an endoscope is used as a means for bending the flection  13 . A wire (not shown) connected to the knot ring  24  is arranged inside the guiding unit  12  and the flection  13  and the flection  13  can be bent in any direction by operating the wire. 
     A TEE probe may be bitten by the patient while being used or the angle tube may be damaged due to an external force while being handled or ageing. If the angle tube is fractured and a hole is cut, a problem of the inner mechanism being affected by a liquid breaking in or of becoming a source of infection after bacteria being propagated in the hole may arise. 
     Thus, a mechanism capable of detecting insulation between water around the tip unit  11  and metal inside the probe by soaking the tip unit  11  and the flection  13  in the inspection before using the TEE probe is used. 
     Before describing an operation to detect presence/absence of a hole in the outer angle tube  23 , an overall configuration of the TEE probe shown in  FIG. 4  will be described. The TEE probe includes, as described above, the tip unit  11  introduced into the esophagus, the flection  13 , and the guiding unit  12  and also includes an air connector  41  provided at some midpoint of the guiding unit and containing a pump to send a liquid or an air to the tip unit  11  in the manufacturing process, a bending operation unit  42  that performs a bending operation of the flection  13 , a connector unit  43 , a signal transmission/reception unit  44  that transmits a driving signal to the connector unit  43  and the ultrasonic transducers  14  via the connector unit  43  and receives an electric signal converted from a wave received by the ultrasonic transducers  14 , and an electric signal line  45  connected to the signal transmission/reception unit  44  and the ultrasonic transducers  14 . With one electrode grounded, the ultrasonic transducers  14  vibrate due to a driving signal applied to the other electrode and transmitted from the signal transmission/reception unit  44 . Normally, a liquid or a gas is emitted from the tip unit  11 . 
     In  FIG. 4 , the electric signal line  45  is shown by a dotted line. Though the electric signal line  45  is shown in  FIG. 4  as a curve, the electric signal line  45  is actually constituted of, for example, a wire inside the flection  13  and the guiding unit  12  and provided in a spiral shape. Moreover, instead of one line, the electric signal line  45  is composed of a plurality of lines such as two drive controlling lines to drive the ultrasonic transducers and a received signal transmission line that transmits a received signal from the ultrasonic transducers. Therefore, the TEE probe constitutes an intracorporeal monitoring apparatus having a flection. 
     An operator operates the bending operation unit  42  to manipulate the bending direction of the flection  13  and the angle thereof. The orientation of the tip unit can be changed by changing the direction of the flection  13 . Accordingly, an ultrasonic wave transmitted/received by the ultrasonic transducers  14  provided in the tip unit  11  can be oriented in a desired direction. 
       FIG. 4  shows an example of the configuration to detect presence/absence of a hole in the outer angle tube  23  of the flection  13 . 
     The tip unit  11 , the flection  13 , and a portion of the guiding unit  12  of a TEE probe are soaked in a liquid bath  47  filled with a physiological saline solution  46 . 
     An electrode  48  is soaked in the physiological saline solution  46  of the liquid bath  47 . A ground-side line of the drive controlling lines leading to the connector  43  and driving the ultrasonic transducers and a lead wire  49  are connected to the electrode  48  and an ammeter  50  is connected to some midpoint of the lead wire  49  to apply a high voltage. 
     The outer angle tube  23  is insulating and if the outer angle tube  23  functions normally, almost no current flows through the ammeter. If the angle tube  23  has a hole, the needle of the ammeter  50  jumps, which indicates that the outer angle tube  23  is not insulated. 
     If the presence of a hole in the outer angle tube  23  is detected, it is necessary to replace the angle tube. In contrast to an endoscope, a TEE probe secures a wide surface that emits an ultrasonic wave of the ultrasonic transducers to obtain an excellent ultrasonic image so that in most cases the diameter thereof is larger in the tip unit  11  than in the guiding unit  12 . 
     This is because with a wider ultrasonic emitting surface, the signal to noise ratio (S/N) becomes better and the focus can advantageously be reduced in terms of resolution. 
     An angle tube has almost the same diameter as the guiding unit  12  and it is necessary for the angle tube to pass through the tip unit  11  having a larger diameter for replacement. While the angle tube has stretching properties necessary for bending, fluorubber is frequently used as a material thereof and has its limit to stretchability. Thus, if the angle tube is made thicker, the overall stretch amount decreases so that the angle tube may not be replaceable beyond the tip unit  11 . 
     Flexing resistance properties are demanded for a TEE probe having no optical system so that the TEE probe is not abruptly bent in the throat or esophagus during insertion. Therefore, an optimal thickness is calculated from the elastic constant of the rubber used for the angle tube. However, the angle tube cannot be made to have an optimal thickness due to a problem of stretchability for replacement so that there is a tradeoff relation between ultrasonic image performance and flexing resistance properties. 
     Thus, in the present embodiment, a configuration of coating the flection  13  doubly with the angle tubes  22  and  23  is adopted. In this manner, each angle tube is made easier to stretch and also easier to replace. Then, the elastic constant of rubber can be made an optimal value of flexing resistance properties with the whole rubber of two angle tubes. 
     Further, while the outer angle tube  23  (outermost layer) uses non-conductive rubber such as fluorubber like a conventional TEE probe, the inner angle tube  22  (inner layer) is configured to have conductivity. 
     Angle tube materials having conductivity include a material obtained by mixing a conductive filler with silicon tube as a base material. Silicon rubber is a material superior in biocompatibility and also rich in stretchability while ensuring safety of a living body, making silicon rubber a suitable material for the angle rubber  22 . The inner angle tube  22  having conductivity and the angle links  21  are electrically connected. Accordingly, if a hole is cut in the outer angle tube  23 , a fracture of the outer angle tube  23  can be detected by the above inspection. 
     If the degree of fracture is severe and a hole reaches the angle  2 , a fracture of the outer angle tube  23  can be detected by a similar inspection. However, whether only the outer angle tube  23  is fractured or both the angle tubes  22  and  23  are fractured cannot be distinguished and thus, it is desirable to replace both the angle tubes  22  and  23  when an angle tube fracture is detected. 
     By adopting a double structure of the outermost layer and the inner layer of angle rubber in the present embodiment, as described above, the thickness of the whole angle tube can be made a thickness having the optimal flexing resistance properties so that the flexing resistance properties can be improved. Moreover, the thickness of each angle tube can be made thinner than a conventional angle tube and thus, the angle tube can be replaced without changing the size of the tip unit. Therefore, excellent ultrasonic images can be obtained without sacrificing obtained ultrasonic images. 
     In the present embodiment, a case of one inner layer, that is, an angle tube of a two-layer structure as a whole is described. In some cases, it is advantageous to design two inner layers or more, instead of one later. That is, after the size of the tip unit  11  that decides ultrasonic image performance and the thickness of the whole angle tube of the flection  13  so as to have optimal flexing resistance properties being independently designed, the number of layers of the angle tube is decided so that the angle tube can be replaced beyond the tip unit  11 . 
     In such a case, the angle tube in the outermost layer is made insulating and other inner layers conductive. Accordingly, a TEE probe can be made an F-type applied portion. 
     According to a TEE probe in the present invention, the angle tube can be inspected by a method similar to a conventional one and further, a tip unit of the conventional size can be used so that no image quality is sacrificed. Moreover, flexing resistance properties of the flection can be improved without affecting durability or costs of a mechanism unit. 
     In the above embodiment, a case where a structure having a flection of the present invention is applied to a TEE probe is described. However, the present invention can be applied not only to a TEE probe, but also to a laparoscope or endoscope having a flection. 
       FIG. 5  shows a perspective view when an embodiment of the present invention is applied to an ultrasonic laparoscope. This perspective view shows a notch sectional view in a portion thereof. A flection  52  is provided between a tip unit  50  and a guiding unit  51  of the ultrasonic laparoscope and the flection  52  has, as shown in  FIG. 2  of the above embodiment, angle links  51   a  coated doubly with an inner angle tube  52  and an outer angle tube  53  therewithout. The angle links  51   a  are axis-connected by a knot ring  54 . 
     The tip unit  50  has a structure in which ultrasonic transducers  55  are arranged around the side surface of a cylindrical body in a longitudinal direction with respect to the central axis. These ultrasonic transducers  55  are driven by being sequentially switched by, for example, a driving signal from the signal transmission/reception unit  44  via the connector unit  43  shown in  FIG. 4  and the flection  52 . A reflected wave of an ultrasonic wave transmitted from a plurality of the ultrasonic transducers  55  is received again by these ultrasonic transducers  55  and processed by the signal reception unit after being converted into an electric signal and passed through the flection. 
     The ultrasonic laparoscope constitutes an intracorporeal monitoring apparatus having a flection. 
     With the configuration shown in  FIG. 4 , an ultrasonic laparoscope in the present embodiment can also detect presence/absence of a hole in the outer angle tube easily. That is, an ammeter is provided between a signal line passing from the tip unit through the flection and guiding unit and an electrode soaked in a liquid bath filled with a physiological saline solution and a high voltage is applied. Based on the magnitude of a current flowing through the electric signal line, presence/absence of a hole on the outer angle tube can be detected. 
     Angle tube materials having conductivity include a material obtained by mixing a conductive filler with silicon rubber as a base material. Silicon rubber is a material superior in biocompatibility and also rich in stretchability while ensuring safety of a living body, making silicon rubber a suitable material for the angle tube. 
     According to the present embodiment, an ultrasonic laparoscope whose angle tube can easily be replaced and capable of easily detecting a hole in the outer angle tube can be obtained. 
     Next, another embodiment when the structure of a flection of the present invention is applied to an endoscope will be described. 
       FIG. 6  shows a perspective view when an embodiment of the present invention is applied to an endoscope. This perspective view shows a notch sectional view in a portion of a flection  62 . The flection  62  is provided between a tip unit  60  and a guiding unit  61  of the endoscope and the flection  62  has, as shown in  FIG. 2  of the above embodiment, angle links  61   a  coated doubly with an inner angle tube  62  and an outer angle tube  63  therewithout. The angle links  61   a  are axis-connected by a knot ring  64 . 
     Two optical systems are provided at the tip of the tip unit  60 . One is an illuminating optical system  65  and the other an observational optical system  66 . Light is shone from the tip unit  60  by the illuminating optical system  65 . This light is guided by, for example, a light guide via the flection and guiding unit. The observational optical system  66  is used to receive reflected light from tissues of a subject of the light shone by the illuminating optical system. 
     The received light undergoes photoelectric conversion by CCD connected thereafter before being transmitted as an electric signal to the signal transmission/reception unit as shown, for example, in  FIG. 4  via the flection and guiding unit. 
     A liquid or a gas may be emitted from the tip unit  60 . The endoscope constitutes an intracorporeal monitoring apparatus having a flection. Angle tube materials having conductivity include a material obtained by mixing a conductive filler with silicon rubber as a base material. Silicon rubber is a material superior in biocompatibility and also rich in stretchability while ensuring safety of a living body, making silicon rubber a suitable material for the angle rubber  22 . 
     With the configuration shown in  FIG. 4 , an endoscope in the present embodiment can also detect presence/absence of a hole in the outer angle tube easily. That is, an ammeter is provided between a signal line passing from the tip unit through the flection and guiding unit and an electrode soaked in a liquid bath filled with a physiological saline solution and a high voltage is applied. Based on the magnitude of a current flowing through the electric signal line, presence/absence of a hole on the outer angle tube can be detected. In the case of the endoscope, a dedicated valve (air connector) to send the air to the tip unit is in most cases provided. 
     In the above embodiments, a laparoscope using an ultrasonic wave and an endoscope using optical systems have been described. However, if the above structure of a flection is provided, the present invention can also be applied to a laparoscope using optical systems or an endoscope using an ultrasonic wave and thus, such embodiments are also included in the scope of the present invention. 
     Conventionally, an endoscope detects a tube break or a pinhole based on a change in pressure after pneumatic pressure being applied from a control unit. However, a TEE probe normally does not have a means for detecting air leakage. In the present invention, insulation properties of the outermost tube are electrically detected without applying pneumatic pressure. Therefore, according to detection of insulation shown in  FIG. 4 , when compared with detection by applying pneumatic pressure, there is an advantage of a shorter measuring time. 
     Conductive tubes are used for inner tubes and a break of only the outer layer can also be detected by measurement of electric insulation resistance so that a break of the outermost layer can be detected by measurement of insulation resistance as a product structure. 
     The present invention is not limited to the above embodiments only and can be embodied by modifying components thereof without deviating from the scope thereof when the present invention is carried out. Various inventions can be formed by appropriately combining a plurality of components disclosed in the above embodiments. 
     For example, some components may be deleted from all components shown in an embodiment. Further, components common to different embodiments may appropriately be combined. These modifications are also included in the present invention as long as technical ideas of the present invention are used.