Electronic stethoscope

Abstract

To provide an electronic stethoscope that can always accurately discern shunt sounds generated when blood flows from a high-pressure artery to a low-pressure vein at a shunt anastomosis of a dialysis patient by keeping the degree of application (force, pressing force) of a chest piece almost constant at all times. [Solution] Electronic stethoscope 1 includes a horn 3 for collecting sound by placing it against a target for auscultation, and a case 4 for supporting horn 3. Horn 3 also includes a horn body 10 that is substantially cylindrical with a bottom, and a chest piece 11 that is inserted into horn body 10 from the front end opening and supported therein so as to be slidable back and forth. A coil spring 18 is interposed between bottom plate 23 of horn body 10 and the rear end face of chest piece 11, and chest piece 11 can be pushed into horn body 10 by a certain distance from a state in which coil spring 18 is at its free length.

Description

[Technical Field]

[0001] The present invention relates to an electronic stethoscope, and more particularly to an electronic stethoscope that can always accurately hear the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein through a shunt anastomosis in, for example, a dialysis patient. [Background technology]

[0002] Conventional electronic stethoscopes are highly versatile and can be used to diagnose a variety of diseases when used by skilled medical professionals. However, in exchange for this versatility, some challenges may arise when using them for specific purposes.

[0003] For example, for patients requiring dialysis (dialysis patients), a bypass may be created by shunting a vein in the arm to an artery to ensure sufficient blood flow to the vein. (The area where the artery and vein are joined is called a "shunt anastomosis," and it can sometimes become uneven (called a shunt aneurysm).) Whether a stenosis has occurred at the shunt anastomosis can be determined by listening to the so-called shunt sound, which occurs when blood flows from a high-pressure artery to a low-pressure vein through the shunt anastomosis, using an electronic stethoscope. While this determination is easy for a skilled medical professional, it is often difficult for dialysis patients or their family members to make. Furthermore, conventional electronic stethoscopes have an extremely robust structure to withstand long-term use while suppressing noise interference, which results in cumbersome disassembly and assembly.

[0004] Incidentally, shunt sounds produce specific frequencies or waveforms depending on whether or not there is stenosis at the shunt anastomosis. Therefore, converting sound waves into electrical signals and processing them analogically to extract specific signals can make the diagnosis easier. Furthermore, digital processing of the signals is expected to enable automatic and highly sensitive identification of the presence or absence of stenosis at the shunt anastomosis. These developments will allow dialysis patients or their families to routinely make auscultatory diagnosis.

[0005] In electronic auscultation technology, the technical focus is on the means and structure for collecting sounds emitted by the living body and converting them into electrical signals. Sounds emitted by the living body, such as shunt sounds, are very weak, and even the slightest noise can interfere with accurate diagnosis. Furthermore, electronic stethoscopes must be particularly easy to use, as patients often have physical functional problems. Furthermore, the ease of disassembly and reassembly for maintenance and other purposes must also be taken into consideration.

[0006] Therefore, the present applicant has previously proposed an electronic stethoscope that is simple and easy to handle, yet capable of eliminating noise contamination (see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7377560 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the electronic stethoscope proposed in Patent Document 1 is simple and easy to use and can eliminate noise contamination, the following problems remain. That is, when placing the chest piece of an electronic stethoscope on a dialysis patient, especially on the shunt anastomosis, it is generally ideal to place it in the same place (point) and with the same degree of pressure (same amount of force, same amount of pressure), but there is a problem that depending on the degree of pressure (degree of force, amount of pressure), the blood vessel may be crushed, causing the auscultation sound (shunt sound) to change (there is a risk of misjudging whether or not stenosis has occurred at the shunt anastomosis). This problem is particularly pronounced when the auscultation is performed by the dialysis patient themselves or their family members who do not have sufficient skills. Therefore, the inventors conducted further intensive research and as a result came up with a mechanism that can keep the chest piece's contact (force, pressing force) almost constant at all times, thereby completing the present invention.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide an electronic stethoscope that keeps the fit (force, pressure) of the chest piece almost constant at all times, making it possible to always accurately hear the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein at the shunt anastomosis of a dialysis patient, for example. [Means for solving the problem]

[0010] In order to achieve the above object, the electronic stethoscope according to the present invention comprises: (1) An electronic stethoscope comprising a horn for collecting sound by placing it on the object of auscultation and a case for supporting the horn, The horn includes a horn body having a generally cylindrical shape with a bottom, and a chest piece inserted and supported in the horn body from a front end opening thereof so as to be slidable back and forth, An elastic body is interposed between the bottom plate of the horn body and the rear end surface of the chest piece, The chestpiece is characterized in that the elastic body can be pushed into the inside of the horn body by a certain distance from a state in which the elastic body is at a free length.

[0011] The above-mentioned configuration (1) of the electronic stethoscope of the present invention has the following effects. Here, the distance the chestpiece can be pushed in from the state where the elastic body is at its free length is set as the allowable range of the chestpiece's sliding movement, taking into account the free length and elastic constant of the elastic body, etc. In other words, within this allowable range, the repulsive force of the elastic body falls within a certain range, making it possible to always place the chestpiece against the target of auscultation (for example, the skin surface of the forearm at the site of the shunt anastomosis of a dialysis patient) with a nearly constant degree of contact (force, pressure). Therefore, according to the configuration (1) above, it is possible to provide an electronic stethoscope that can always accurately hear the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein at the shunt anastomosis of a dialysis patient, by always keeping the fit of the chest piece (force, pressure) almost constant. Furthermore, by using the electronic stethoscope configured as described in (1) above, even when a dialysis patient or their family member is performing the auscultation, it is possible to always apply the chest piece to the skin surface of the dialysis patient's forearm at the location of the shunt anastomosis with a nearly constant contact force (force, pressure). As a result, it is possible to prevent the blood vessel from being crushed, which would change the auscultation sound (shunt sound) (there is also no risk of misjudging whether or not a stenosis has occurred at the shunt anastomosis).

[0012] In the above-mentioned configuration (1) of the electronic stethoscope of the present invention, it is preferable to have the following configurations (2) to (10).

[0013] (2) In the above configuration (1), the elastic body is one selected from the group consisting of a spring, rubber, plastic, and silicone.

[0014] (3) In the configuration of (1) above, the chest piece is lightly attached to the inner surface of the horn body in a state where it can slide back and forth. The preferred configuration of (3) above allows the chestpiece to slide back and forth while increasing the airtightness of the space enclosed by the horn (horn body and chestpiece). As a result, sound waves picked up by the chestpiece can be transmitted to the microphone inside the case without loss (see configuration (5) below), and the effects of external noise can be eliminated.

[0015] (4) In the configuration of (1) above, a hole is drilled through the bottom plate of the horn body.

[0016] (5) In the configuration of (1) above, a substrate to which a microphone is fixed is housed inside the case, and the horn and the microphone are connected by a cylindrical joint member made of an elastic material with openings on both ends.

[0017] (6) In the above configuration (5), the joint member is made of a viscoelastic material. According to the preferred configuration (6) above, the viscoelastic joint member deforms appropriately, facilitating assembly and disassembly. Furthermore, the viscoelastic joint member maintains close contact with the horn and microphone, enhancing the airtightness of the space enclosed by the horn, joint member, and microphone. As a result, sound waves picked up by the chestpiece can be transmitted to the microphone without loss. Furthermore, the viscoelastic joint member also helps eliminate noise through its vibration-damping effect.

[0018] (7) In the configuration of (1) above, the chestpiece comprises a chestpiece body and a diaphragm provided so as to cover the front end surface of the chestpiece body.

[0019] (8) In the configuration of (7) above, the diaphragm is made of a soft material. According to the preferred configuration of (8) above, the diaphragm can be fitted more closely to the shunt anastomosis, which has become uneven due to a shunt aneurysm on the forearm of a dialysis patient, for example. As a result, it becomes possible to pick up more of the shunt sound transmitted from the shunt anastomosis and reduce external noise.

[0020] (9) In the above configuration (8), the soft material is one selected from polyurethane, soft PVC, and silicone.

[0021] (10) In any of the above configurations (7) to (9), the diaphragm is formed in a dome shape that protrudes forward. The preferred configuration of (10) above makes it possible to improve the adhesion of the diaphragm to the shunt anastomosis, which has become uneven due to a shunt aneurysm, for example, on the forearm of a dialysis patient, thereby making it possible to pick up more of the shunt sound transmitted from the shunt anastomosis and reduce external noise. [Effects of the Invention]

[0022] According to the present invention, an electronic stethoscope can be provided that keeps the fit (force, pressure) of the chest piece almost constant at all times, making it possible to always accurately hear the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein at the shunt anastomosis of a dialysis patient, for example. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing the external configuration of an electronic stethoscope according to one embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view (with the diaphragm omitted) showing the external configuration of the electronic stethoscope according to one embodiment of the present invention. [Figure 3] FIG. 3 is an exploded perspective view of the electronic stethoscope according to one embodiment of the present invention, showing the horn removed from the case. [Figure 4] 4 is a cross-sectional view taken along line IV-IV-IV in FIG. [Figure 5] FIG. 5 is a cross-sectional view showing a state in which the chestpiece is pushed into the horn body in the electronic stethoscope shown in FIG. [Figure 6] Figure 6 is a schematic diagram showing how to use an electronic stethoscope in one embodiment of the present invention (with the diaphragm of the chestpiece lightly pressed against the skin surface of the forearm of a dialysis patient at the location of the shunt anastomosis). [Figure 7] FIG. 7 is a schematic diagram showing how to use the electronic stethoscope according to one embodiment of the present invention (with the case pressed forward (towards the chestpiece; downward in FIG. 7)). DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described in more detail below using preferred embodiments, but the following embodiments are merely examples of realizing the present invention and the present invention is not limited thereto.

[0025] [Electronic stethoscope configuration] First, the configuration of the electronic stethoscope in this embodiment will be described with reference to FIGS.

[0026] FIG. 1 is a perspective view showing the external configuration of the electronic stethoscope in this embodiment, FIG. 2 is a perspective view showing the external configuration of the electronic stethoscope (with the diaphragm omitted), FIG. 3 is an exploded perspective view showing the electronic stethoscope with the horn removed from the case, FIG. 4 is a cross-sectional view taken along line IV-IV-IV in FIG. 1, and FIG. 5 is a cross-sectional view showing the state in which the chest piece is pushed into the horn body in the electronic stethoscope shown in FIG. 4.

[0027] In the following description and the appended claims, the distinction between "front" and "rear" is based on the direction toward the target of auscultation (for example, the skin surface of the forearm 30 of a dialysis patient at the location of the shunt anastomosis 2; see Figures 6 and 7 described below). That is, the direction closer to the target of auscultation is "front," and the direction closer to the case 4 or the operator holding the case 4 (e.g., a medical professional, the dialysis patient, or their family member) is "rear" (see Figure 1, etc., and Figures 6 and 7 described below). For ease of explanation, arrows indicating "upper" and arrows indicating "lower" are attached to Figure 1. In Figures 4 and 5, "upper" corresponds to "front" in Figure 1, and "lower" corresponds to "rear" in Figure 1. In Figures 6 and 7 described below, "lower" corresponds to "front" in Figure 1, and "upper" corresponds to "rear" in Figure 1.

[0028] The electronic stethoscope 1 of this embodiment shown in Figure 1 etc. can be used, for example, to convert sounds generated by blood flow (vascular murmurs) into electrical signals, and in particular, can be used to detect shunt sounds generated when blood flows from a high-pressure artery to a low-pressure vein at a site where an artery and a vein are artificially connected (short-circuited) for hemodialysis (shunt anastomosis 2 (see Figures 6 and 7 described below)). Needless to say, the electronic stethoscope 1 of this embodiment can be used more generally and can also be used to detect sounds generated in other parts of the body, such as other circulatory or respiratory organs.

[0029] As shown in Figures 1 to 4, the electronic stethoscope 1 of this embodiment comprises a horn 3 for collecting sound by placing it against the object of auscultation (for example, the skin surface of the forearm 30 of a dialysis patient at the location of the shunt anastomosis 2; see Figures 6 and 7 described below), and a case 4 for supporting the horn 3.

[0030] (Case configuration) As shown in Figures 1 to 4, case 4 has a substantially circular opening 5 that receives horn 3. An electronic board (not shown) is housed inside case 4, and a thin, truncated cone-shaped microphone 6 is fixed on the electronic board. Horn 3 and microphone 6 are connected by a cylindrical joint member 7 that is open on both ends, and a cylindrical through-hole 7a that passes through joint member 7 transmits sound waves collected by horn 3 to microphone 6.

[0031] A suitable elastic material can be used for the joint member 7. The elastic material is preferably a viscoelastic material, one example of which is an elastomer such as silicone. The joint member 7 made of such a viscoelastic material can be deformed appropriately, making it easy to assemble and disassemble. Furthermore, the joint member 7 made of such a viscoelastic material can maintain close contact with the horn 3 and microphone 6, thereby improving the sealing of the space surrounded by the horn 3, joint member 7, and microphone 6. As a result, sound waves picked up by the chestpiece 11 can be transmitted to the microphone 6 without loss. Furthermore, the joint member 7 made of such a viscoelastic material also helps to eliminate noise through its vibration-damping effect. The joint member 7 has an outer diameter of approximately 12.0 mm, and the through-hole 7a has a diameter of approximately 6.0 mm. The height of the joint member 7 in the front-to-back (up-and-down) direction is approximately 10.0 mm.

[0032] The case 4 is made of a resin such as a white grade of polycarbonate (PC) and has a cavity therein capable of accommodating the electronic boards and the like. The outer shape of the case 4 is appropriately shaped so that it can be easily held by an operator (such as a medical professional, a dialysis patient, or a family member). Specifically, as shown in FIGS. 1 to 3, the outer shape of the case 4 is a generally rectangular parallelepiped (approximately 21.0 mm × approximately 53.0 mm × approximately 44.0 mm) that is short in the front-to-back direction, long in the up-to-down direction, and has rounded corners. Of course, the outer shape of the case is not limited to the example shown in the drawings, and any appropriate shape can be adopted taking into consideration the ease of accommodating the electronic boards and the ease of gripping by the operator.

[0033] The case 4 can have several openings in addition to the opening 5 for receiving the horn 3. In the example shown, it has an earphone jack opening 9 on the side for exposing the earphone jack. Also, although not shown in the drawings, it may have an opening for connecting a general-purpose bus connector. Of course, other openings can also be provided as appropriate.

[0034] To facilitate the installation of the electronic boards and other components inside, the case 4 is preferably disassembled into two or more parts, either front to back or top to bottom (see FIG. 1). The case 4 is preferably composed of a case body made of a resin such as white polycarbonate (PC) and a cover that covers the case body. For the cover, an elastomer such as silicone can be used for anti-slip or sound insulation purposes, but this is not a limitation. When assembling, the electronic boards and other components are first installed in the disassembled case body, and then the case bodies are joined together and the cover is placed over the case body.

[0035] Opening 5 is opened in the front (top) surface of case 4 and receives rear end (lower end) 8 of horn 3. Microphone 6 has the outline of a thin truncated cone as described above, and is fixed on the electronic board with its sound collecting end facing opening 5. The position of microphone 6 on the electronic board is set so that microphone 6 is coaxial with opening 5 when the electronic board is installed in case 4.

[0036] The electronic board includes at least an electrical circuit that converts the sound waves picked up by the microphone 6 into an analog signal, and more preferably an amplifier circuit that amplifies the analog signal and a digital-to-analog converter circuit that converts the analog signal into a digital signal. The circuit on the electronic board may further include a processor that processes the digital signal and controls the operation of the entire circuit, and an interface for outputting signals. The earphone jack and general-purpose bus connector described above can be used to output these analog and digital signals.

[0037] Any microphone can be used as the microphone 6, for example, a well-known dynamic microphone, a carbon microphone, a condenser microphone, a piezoelectric microphone, etc. Alternatively, an alternative element such as a vibration sensor can also be used as the microphone 6.

[0038] (Horn configuration) As shown in Figures 1 to 4, horn 3 is made of a resin such as a white grade of polycarbonate (PC) and includes a horn body 10 that is approximately cylindrical and has a bottom, and a chestpiece 11 that is inserted into and supported by the front (top) opening of horn body 10 so that it can slide back and forth (up and down) (see arrows A and B in Figure 1 and arrows C and D in Figure 4).When horn 3 is supported by case 4, it protrudes forward (upward) from case 4.A circular hole 24 is drilled through the center of bottom plate 23 of horn body 10.The diameter of circular hole 24 is approximately 5.8 mm. The length by which horn 3 protrudes from case 4 can be selected as appropriate, and for example, horns of various lengths may be interchangeable depending on the application.

[0039] The chestpiece 11 includes a chestpiece body 12 and a diaphragm 13 provided to cover the front end (upper end) surface of the chestpiece body 12. The chestpiece main body 12 comprises a two-stage, approximately cylindrical front (upper) section 14 and a cylindrical rear (lower) section 15 that is inserted and supported from the front (upper) opening of the horn main body 10 into the interior of the horn main body 10 so that it can slide back and forth (up and down) (see arrows A and B in Figure 1 and arrows C and D in Figure 4).

[0040] The outer diameter of the small diameter portion of the front (upper) section 14, which is a two-stage, approximately cylindrical section, is approximately 18.5 mm, and the outer diameter of the large diameter portion is approximately 35.0 mm. The height of the small diameter portion of the two-stage, approximately cylindrical front (upper) portion 14 in the front-to-back (upper-to-lower) direction is approximately 3.0 mm, and the height of the large diameter portion is approximately 5.0 mm. The cylindrical rear (lower) portion 15 has an outer diameter of approximately 11.5 mm and a length in the front-to-rear (up-and-down) direction of approximately 15.0 mm.

[0041] A generally cylindrical cavity 16 with an opening at the front end (top end) is formed on the front end (top end) side of the front (upper) section 14 of the chestpiece body 12, and a through-hole 17 that communicates with the cavity 16 is formed from the center of the bottom surface of the cavity 16 to the center of the rear (lower) surface of the rear (lower) section 15. The bottom surface of the cavity 16 slopes downward from the periphery toward the center. The diameter of the through-hole 17 is the same as the diameter of the circular hole 24 in the bottom plate 23 of the horn body 10, and when the rear (lower) section 15 of the chestpiece body 12 is inserted and supported inside the horn body 10, the through-hole 17 is coaxial with the circular hole 24.

[0042] The cavity 16 has an inner diameter of about 28.0 mm and a height in the front-to-back (up-and-down) direction of about 3.5 mm. The diameter of the through-hole 17 is approximately 5.8 mm.

[0043] A cylindrical hole 22 is formed inside the horn body 10, into which the cylindrical rear (lower) section 15 of the chestpiece body 12 is inserted and supported. The diameter of the cylindrical hole 22 is slightly smaller at the rear (lower) section, and the rear (lower) section of a coil spring 18 (shown by a two-dot chain line) is fitted into this smaller diameter section. The coil spring 18 is positioned so that its central axis faces the front-to-rear (up-and-down) direction. The rear (lower) surface of the rear (lower) section 15 of the chestpiece body 12 abuts against the front (upper) surface of the coil spring 18. In other words, the coil spring 18 is interposed between the bottom plate 23 of the horn body 10 and the rear (lower) surface of the chestpiece 11. Therefore, when the rear (lower) section 15 of the chest piece main body 12 is pushed inward (rearward (downward)) of the horn main body 10 from the state shown in Figure 4 (see arrow B in Figure 1 and arrow D in Figure 4), the coil spring 18 contracts in the front-to-back (up-and-down) direction as shown in Figure 5, and the repulsive force of the coil spring 18 generates a pressing force in the front (upward) direction on the chest piece 11 (see arrow E in Figure 5).

[0044] The cylindrical hole 22 has a depth in the front-to-back (up-and-down) direction of about 12.5 mm and a hole diameter of about 12.0 mm (the hole diameter of the small diameter portion is about 10 mm).

[0045] Two parallel annular grooves 25, 26 are formed in the outer peripheral surface of the rear (lower) part of rear (lower) part 15 of chestpiece body 12, and O-rings 27, 28 are fitted into these annular grooves 25, 26. O-rings 27, 28 lightly fit into the inner peripheral surface of cylindrical hole 22 of horn body 10, allowing chestpiece 11 to slide back and forth (up and down) while improving the airtightness of the sound wave transmission space (see FIG. 4) consisting of cavity 16, through-hole 17, cylindrical hole 22, circular hole 24, and through-hole 7a (improving the airtightness of the space surrounded by horn 3, joint member 7, and microphone 6). A rounded annular ridge 29 is provided on the inner peripheral surface of the front end (top end) of horn body 10. An O-ring 27 is engaged with annular ridge 29 to prevent chestpiece 11 from easily coming off horn body 10. As a result, chestpiece 11 can slide back and forth (up and down) only between the rear end (bottom end) surface of front stage (top stage) part 14 of chestpiece body 12 and the front end (top end) surface of horn body 10 (distance L) when coil spring 18 is at its free length, as shown in FIG. Here, "the distance L between the rear end (lower end) surface of the front (upper) section 14 of the chest piece main body 12 and the front end (upper end) surface of the horn main body 10 when the coil spring 18 is at its free length" can also be defined as "the distance the chest piece 11 can be pushed in from the state when the coil spring 18 is at its free length."

[0046] This distance L that the chestpiece 11 can slide back and forth (up and down) (the distance the chestpiece 11 can be pushed in from a state in which the coil spring 18 is at its free length) is set as the allowable range of the sliding movement of the chestpiece 11, taking into consideration the free length, spring constant, etc. of the coil spring 18. In other words, within this allowable range, the repulsive force of the coil spring 18 is within a certain range, allowing the chestpiece 11 to be placed against the target of auscultation (for example, the skin surface of the forearm 30 of a dialysis patient at the location of the shunt anastomosis 2; see Figures 6 and 7 described below) with a nearly constant degree of contact (force, pressure).

[0047] Therefore, according to the configuration of the electronic stethoscope 1 of this embodiment, it is possible to provide an electronic stethoscope that can always accurately hear the shunt sound generated when blood flows from a high-pressure artery to a low-pressure vein through the shunt anastomosis 2 of a dialysis patient, by always keeping the fit (force, pressing force) of the chest piece 11 almost constant.

[0048] Furthermore, by using the electronic stethoscope 1 of this embodiment, even when a dialysis patient or their family members who do not have sufficient skills perform auscultation, it is possible to always place the chestpiece 11 on the target of auscultation (for example, the skin surface of the forearm 30 of a dialysis patient at the location of the shunt anastomosis 2; see Figures 6 and 7 described below) with a nearly constant contact (force, pressure). As a result, it is possible to prevent the blood vessel from being crushed, which would cause a change in the auscultation sound (shunt sound) (there is also no risk of misjudging whether or not a stenosis has occurred at the shunt anastomosis 2).

[0049] A round wire coil spring (model number: UF10-10) manufactured by Misumi Group Holdings Co., Ltd. was used as the coil spring (spring) 18. This round wire coil spring has a free length of 10 mm, a solid height of approximately 4.6 mm (design value), a wire diameter of 0.65 mm, an outer diameter Φ of 10 mm, and a spring constant of 0.49 N / mm. Furthermore, when the coil spring 18 is at its free length as shown in Figure 4, the distance L between the rear end (lower end) surface of the front (upper) section 14 of the chest piece main body 12 and the front end (upper end) surface of the horn main body 10 (the allowable width of the sliding movement of the chest piece 11) is approximately 7.0 mm.

[0050] The rear end (lower end) portion 8 of the horn 3 is used to connect to the case 4 and is sized to fit into the opening 5 of the case 4. The rear end (lower end) portion 8 may also have a structure for fixing it to the opening 5, an example of which is a key 19 shown in FIG. 3 . Correspondingly, the opening 5 may have a lip 20 and a keyway 21. Here, the keys 19 and the keyways 21 are provided in pairs, each spaced 180° apart. The rear end (lower end) portion 8 of the horn 3 can be inserted into the opening 5 by aligning the key 19 with the keyway 21. Further, by twisting the horn 3 around its axis, the key 19 engages with the lip 20, and the horn 3 is supported and fixed to the case 4. Of course, the structure for supporting and fixing the horn 3 to the case 4 is not limited to this. For example, screws, a latch mechanism, or a simple interference fit may be freely selected.

[0051] The rear (lower) end 8 of the horn 3 is cylindrical and has an open rear (lower) end. That is, a cylindrical recess is formed in the rear (lower) surface of the rear (lower) end 8. When the horn 3 is fixedly supported by the case 4, the joint member 7 is inserted and held in the cylindrical recess in the rear (lower) end 8 of the horn 3. The diameter of the through hole 7a in the joint member 7 is the same as the diameter of the circular hole 24 in the bottom plate 23 of the horn body 10. When the joint member 7 is inserted and held in the cylindrical recess in the rear (lower) end 8 of the horn 3, the through hole 7a is coaxial with the circular hole 24.

[0052] In this manner, when the horn 3 is supported and fixed to the case 4, the through hole 7a of the joint member 7 is of the same diameter and coaxial with the circular hole 24 in the bottom plate 23 of the horn body 10, and as described above, the through hole 17 of the chest piece body 12 is of the same diameter and coaxial with the circular hole 24 in the bottom plate 23 of the horn body 10. That is, when the horn 3 is supported and fixed to the case 4, a straight cylindrical sound wave transmission space extends from the cavity 16 in the front (upper) part 14 of the chestpiece body 12 to the microphone 6.

[0053] (Diaphragm configuration) The diaphragm 13 is preferably made of a soft material. This preferred configuration allows the diaphragm 13 to fit more closely to the shunt anastomosis 2 (see Figures 6 and 7, described later) of a dialysis patient's forearm 30, which may be uneven due to a shunt aneurysm. As a result, it becomes possible to pick up more of the shunt sound transmitted from the shunt anastomosis 2 and reduce external noise. Examples of soft materials include polyurethane, soft PVC, and silicone.

[0054] As described above, in the electronic stethoscope 1 of this embodiment, the sound wave transmission space consisting of the cavity 16, through-hole 17, cylindrical hole 22, circular hole 24, and through-hole 7a is made highly airtight, so sound waves picked up by the chestpiece 11 can be transmitted to the microphone 6 without loss and the effects of external noise can be eliminated. In addition, the joint member 7 made of a viscoelastic material contacts the horn 3 and microphone 6 and damps their vibration, thereby suppressing the generation of noise itself.

[0055] In addition, the sealed sound wave transmission space surrounded by the horn 3, joint member 7, and microphone 6 becomes a vacuum when the rear (lower) part 15 of the chest piece main body 12 is pushed inward (rearward (downward)) of the horn main body 10 (see arrow B in Figure 1 and arrow D in Figure 4). Therefore, the moment the chest piece 11 is lightly placed against the object of auscultation (for example, the skin surface of the forearm 30 of a dialysis patient at the location of the shunt anastomosis 2; see Figures 6 and 7 described below) (as shown in Figure 6 described below), the soft diaphragm 13 becomes taut, making it easier for the auscultated shunt sounds to be transmitted.

[0056] In other words, when using the electronic stethoscope 1 of this embodiment, the diaphragm 13 is initially soft, allowing the diaphragm 13 to fit over the shunt anastomosis 2 (auscultation point; see Figures 6 and 7 described below) which has become uneven due to the formation of a shunt aneurysm, and when it is time to auscultate, a forward (downward) force is applied to the case 4 of the electronic stethoscope 1 (see arrow F in Figure 6 described below) to push the rear (lower) part 15 of the chest piece main body 12 inward (rearward (downward)) of the horn main body 10, causing the diaphragm 13 to become taut, making it easier for the auscultated shunt sounds to be transmitted.

[0057] As shown in FIGS. 1 and 3 to 5, it is more preferable that the diaphragm 13 is formed in a dome shape that is convex toward the front (upward). This preferred configuration makes it possible to improve the adhesion of the diaphragm 13 to the shunt anastomosis 2 (see Figures 6 and 7 described below) of a dialysis patient's forearm 30, which may have become uneven due to a shunt aneurysm. As a result, it becomes possible to pick up more of the shunt sound transmitted from the shunt anastomosis 2 and reduce external noise. As shown in FIGS. 4 and 5, the rear end (lower end) surface of the diaphragm 13 is formed flat. However, the diaphragm may have a uniform thickness as long as it is formed in a dome shape that is convex toward the front (upward).

[0058] [How to use an electronic stethoscope] Next, the method of using the electronic stethoscope in this embodiment will be explained with reference to Figures 6 and 7, taking as an example the case of listening to the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein at a site where an artery and a vein are artificially short-circuited for hemodialysis (shunt anastomosis).

[0059] Figure 6 is a schematic diagram showing how to use the electronic stethoscope in this embodiment (with the diaphragm of the chest piece lightly pressed against the skin surface of the forearm of a dialysis patient at the location of the shunt anastomosis), and Figure 7 is a schematic diagram showing how to use the electronic stethoscope (with the case pressed forward (towards the chest piece; downward in Figure 7)).

[0060] First, as shown in Figure 6, a dialysis patient grasps the case 4 of the electronic stethoscope 1 and lightly presses the diaphragm 13 of the chestpiece 11 against the skin surface of the patient's forearm 30 at the location of the patient's shunt anastomosis 2. Here, because the diaphragm 13 is made of a soft material, it is possible to fit the diaphragm 13 more closely to the shunt anastomosis 2 on the patient's forearm 30, which has become uneven due to a shunt aneurysm.

[0061] Next, as also shown in FIG. 6, with the artificial dialysis patient gripping the case 4 of the electronic stethoscope 1, a downward (forward) force is applied to the case 4 of the electronic stethoscope 1 (see arrow H in FIG. 6). As a result, as shown in FIG. 7, the rear (upper) portion 15 of the horn body 10 and the chest piece body 12 slide relative to each other, the coil spring 18 contracts in the front-back (up-down) direction, and a pressing force in the front (down) direction is generated on the chest piece 11 by the repulsive force of the coil spring 18 (see arrow T in FIG. 7). And in this case, as shown in FIGS. 4 and 5, the distance between the rear (lower) end surface of the front (upper) portion 14 of the chest piece body 12 and the front (upper) end surface of the horn body 10 changes from L (see FIG. 4) to L1 (<L; see FIG. 5). This change in the distance (L→L1) between the rear (lower) end surface of the front (upper) portion 14 of the chest piece body 12 and the front (upper) end surface of the horn body 10 can be visually observed from the side of the electronic stethoscope 1, so it can be confirmed on the spot that the chest piece 11 is sufficiently pressed against the auscultation target (in this embodiment, the skin surface of the forearm 30 at the location where the shunt anastomosis 2 of the artificial dialysis patient is present). Also, it can be confirmed from the feeling of the palm of the hand pushing the case 4 of the electronic stethoscope 1 downward (forward) that the chest piece 11 is sufficiently pressed against the auscultation target.

[0062] Here, the distance (the possible pushing-in distance of the chest piece 11 from the state where the coil spring 18 is at its free length) L between the rear (lower) end surface of the front (upper) portion 14 of the chest piece body 12 and the front (upper) end surface of the horn body 10 when the coil spring 18 is at its free length, as shown in FIG. 4, is set as the allowable width of the sliding (sliding) operation of the chest piece 11 in consideration of the free length of the coil spring 18, the spring constant, etc. That is, within this allowable width, due to the repulsive force within a certain range of the coil spring 18, the chest piece 11 can always be applied to the skin surface of the forearm 30 at the location where the shunt anastomosis 2 of the artificial dialysis patient is present with a substantially constant condition (force adjustment, pressing force).

[0063] In this way, by using the electronic stethoscope 1 of this embodiment, even when a dialysis patient without sufficient skills performs auscultation, it is possible to always apply the chestpiece 11 to the skin surface of the forearm 30 at the location of the shunt anastomosis 2 of the dialysis patient with a nearly constant application (force, pressure). As a result, it is possible to prevent the blood vessels from being crushed, which would cause a change in the auscultation sound (shunt sound). In other words, by using the electronic stethoscope 1 of this embodiment, it is possible to always keep the pressure (force, pressing force) of the chestpiece 11 almost constant and always accurately hear the shunt sound that occurs when blood flows from a high-pressure artery to a low-pressure vein through the shunt anastomosis 2 of a dialysis patient. This also eliminates the risk of making an incorrect judgment as to whether or not stenosis has occurred at the shunt anastomosis 2.

[0064] Furthermore, in the electronic stethoscope 1 of this embodiment, the chest piece 11 is allowed to slide back and forth (up and down), while increasing the airtightness of the sound wave transmission space surrounded by the horn 3, joint member 7, and microphone 6. Therefore, when a downward (forward) force is applied to the case 4 of the electronic stethoscope 1 (see arrow F in Figure 6) and the rear (upper) part 15 of the chest piece main body 12 is pushed inward (rearward (upward)) of the horn main body 10, the sound wave transmission space becomes a vacuum. Therefore, the moment the chest piece 11 is lightly placed in contact with the skin surface of the forearm 30 of the dialysis patient at the location of the shunt anastomosis 2 (as shown in Figure 6), the soft diaphragm 13 becomes taut, making it easier for the shunt sounds heard through the stethoscope to be transmitted.

[0065] In this embodiment, the elastic body interposed between the bottom plate 23 of the horn body 10 and the rear end surface of the chestpiece 11 is a coil spring 18. However, the present invention is not necessarily limited to this configuration. The elastic body may be a "spring" other than a coil spring, and may also be made of, for example, rubber, plastic, silicone, etc.

[0066] In addition, in this embodiment, the horn 3 components, horn body 10, chest piece 11, and joint member 7, have a generally cylindrical outer shape. However, the present invention is not necessarily limited to this configuration. For example, the horn body, chest piece, and joint member may each have a rectangular parallelepiped outer shape. [Explanation of symbols]

[0067] 1 electronic stethoscope 2 Shunt anastomosis 3 Horn 4 cases 5 aperture 6. Microphone 7 Joint material 7a,17 Through hole 8 Rear end 9 Earphone jack opening 10 Horn body 11 Chest Piece 12 Chest piece body 13 Diaphragm 14 Front section 15. Later part 16 Cavity 18 Coil spring 19 keys 20. Relationship 21 Keyway 22 Cylindrical hole 23 Bottom plate 24 Circular hole 25,26 Annular groove 27,28 O-ring 29 Annular ridge 30 Forearm

Claims

1. An electronic stethoscope comprising a horn for collecting sound by placing it on a target for auscultation, and a case for supporting the horn, The horn includes a horn body having a generally cylindrical shape with a bottom, and a chest piece inserted and supported in the horn body from a front end opening thereof so as to be slidable back and forth, An elastic body is interposed between the bottom plate of the horn body and the rear end surface of the chest piece, The chestpiece is capable of being pushed into the horn body by a certain distance from a state in which the elastic body is at a free length.

2. 2. The electronic stethoscope of claim 1, wherein the elastic body is one selected from the group consisting of a spring, rubber, plastic, and silicone.

3. 2. The electronic stethoscope according to claim 1, wherein the chestpiece is lightly attached to the inner surface of the horn body in a manner that allows it to slide back and forth.

4. 2. The electronic stethoscope of claim 1, wherein a hole is drilled through the bottom plate of the horn body.

5. 2. The electronic stethoscope according to claim 1, wherein a base plate to which a microphone is fixed is housed inside the case, and the horn and the microphone are connected by a cylindrical joint member made of an elastic material and having openings at both ends.

6. The electronic stethoscope of claim 5, wherein the joint member is made of a viscoelastic material.

7. 2. The electronic stethoscope according to claim 1, wherein the chestpiece comprises a chestpiece body and a diaphragm provided to cover a front end surface of the chestpiece body.

8. 8. The electronic stethoscope of claim 7, wherein the diaphragm is made of a soft material.

9. 9. The electronic stethoscope according to claim 8, wherein the soft material is one selected from the group consisting of polyurethane, soft PVC, and silicone.

10. 10. The electronic stethoscope according to claim 7, wherein the diaphragm is formed in a dome shape that is convex toward the front.

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