Apparatus for disintegrating calculuses

Abstract: An apparatus for disintegrating calculuses (22) of the type in which a calculus in a human body of a patient (21) is disintegrated with a shock wave generated by a shock wave generator (12) through medium liquid (16) in an expandable container (13), the medium liquid (16) allowing the shock wave to propagate therethrough, the apparatus comprising a tank (29) storing the medium liquid, a sensor (31), (32) for detecting pressure in the container (13), and liquid control system (25 to 27, 33 to 35), when detected pressure exceeds a preset value, the liquid control system (25 to 27, 33 to 35) draining the medium liquid (16) from the container (13) to the tank (29) till the detected pressure drops below the preset value.

Description: The present invention relates to an apparatus for disintegrating calculuses of the type in which a calculus in a human body of a patient is disintegrated with a disintegrating energy of a shock wave externally applied. The calculus disintegrating apparatus using the disintegrating energy of a shock wave for disintegrating a calculus or calculuses in a human body have been developed as an apparatus for curing a disease by renal calculus or gallstone without surgical operations. In this type of the apparatus, a shock wave is generated by making use of electric spark or ultrasonic wave oscillation, and a calculus in a human body is irradiated with the shock wave to be disintegrated. To effectively irradiate the calculus with the shock wave, it is required that no air layer exists in a propagating path of the shock wave (i.e., between a shock wave generator and the body surface of a patient). The reason for this is that the air layer impedes propagation of the shock wave within the human body because it is reflected by the air layer. This requirement may be readily satisfied by filling the propagation path with medium liquid, e.g., water. There have been known two specific approaches to realize this. In a first method, a shock wave generator is placed in a bath tub filled with water. A patient is sunk into the bath tub. Under this condition, shock wave is radiated toward the patient through the water. In a second method, an expandable container like as rubber bag filled with the medium liquid is disposed in the front of a shock wave generator. The container is made closely contact the body of a patient when the shock wave is radiated. The shock wave generator and the container form a called applicator. In the second method, a patient need not to sink into the bath tub. In this respect, mental and physical strain of a patient is lessened. It is desirable that the applicator is disposed above a patient laid on the bed. The reason for this is that the direction of shock wave radiation may be readily checked, and that an operation of the applicator resembles that of a conventional medical apparatus, such as X-rays apparatus and ultrasound diagnostic apparatus, and therefore such a layout of the applicator above the patient allows an operator, e.g., a doctor, to be easily accessible to the applicator. With the layout of the applicator above the patient, when the applicator is positioned to focus the shock wave generator on the calculus, an operator excessively moves down the applicator or supplies an excessive amount of medium liquid into the applicator, by mistake. Consequently, a patient is strongly pressed against the bed. In other words, where the position of the applicator and the amount of the liquid are both proper, the patient may be comfortably subjected to treatment, without any feeling of the weight of the applicator an the liquid. On other hand, where those are improper, the applicator strongly presses the patient against the bed. Under this condition, the patient feels uncomfortable, and in an extreme case, he has difficulty in breathing, and he may suffer a fracture by an excessive pressure applied. EP-A-0227929 discloses an apparatus for disintegrating calculuses of the type of which a calculus in the human body of a patient is disintegrated with a shock wave generated by a shock wave generator through medium liquid in an expandable container. The medium liquid allows the shock wave to propagate therethrough and is fed from storage means. The medium liquid in the expandable container is connected to a compensating cushion of liquid medium. The Proceedings of the First International Symposium on Biliary Lithotripsy which took place in July 1988 (Editors J.T.Ferrucci et al.) disclose a patient-handling system designed to afford the physician various lithotripsy treatment options. The patient table has longitudinal and transverse travel capabilities, as well as height, head up/head down angulation and side-to-side tilt. The longitudinal and transverse movements are used to move the target into position. Table tilt and angulation are designed to allow the physician to compensate for anatomical variations and present the target in an optimum treatment position. Shock-wave generator means generate shock waves which propagate through a pressure controlled expandable water cushion. The vertical position of the shock-wave generator means and the water cushion can be varied by rotation along a C-arm. Accordingly, an object of the present invention is to provide an apparatus for disintegrating calculuses which protects a patient from an excessive pressure applied thereto even if the applicator, the drain pump and/or the feed water pump improperly operates and/or is mistakenly operated. According to the present invention, there is provided an apparatus for disintegrating calculuses such as calculuses in a human body of a patient with shock waves, the apparatus comprising a shock wave generator which generates shock waves which propagate through a liquid medium in an expandable container, said medium liquid allowing the shock wave to propagate therethrough and being fed from storage means, means for vertically moving said shock wave generator and said container above said patient, pressure detecting means for detecting the pressure in said container, liquid control means, which, when the detected pressure exceeds a preset value, drains said liquid medium from said container to said storage means until said detected pressure drops below said preset value, and means for generating an alarm signal during a period that said detected pressure exceeds said preset value. Preferably, said liquid control means stopping the supply of said liquid medium when said detected pressure exceeds a preset value during the supply of said liquid medium from said storage means to said container. Because the applicator is hermetically closed, pressure in the applicator, particularly pressure in an upper part of the liquid medium within the applicator, acts as a negative pressure in accordance with a depth of the liquid medium, when the apparatus is operated for calculus treatment. Under this condition, if the applicator is pressed against the patient or an amount of the liquid medium is increased, the pressure within the applicator increases and inclines towards a positive pressure. The "preset value" is set at a pressure value at which a patient begins to uncomfortably feel weight of the applicator. When the pressure within the applicator is above the preset value, the liquid medium is drained from the applicator to drop the pressure. When the liquid medium is being supplied to the applicator, the supply of the liquid is stopped when the drainage of the liquid starts. The problems of the uncomfortable feeling and feeling choky are successfully eliminated. Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 shows in block and schematic form an arrangement of an apparatus for calculuses disintegration according to an embodiment of the present invention; Fig. 2 is a flowchart showing a sequence of control steps by a control circuit of the apparatus of Fig. 1; and Figs. 3A to 3D form a timing chart useful in explaining an operation of the apparatus of Fig. 1. A preferred embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 shows in block and schematic form an arrangement of an apparatus for calculuses disintegration according to an embodiment of the present invention. In the figure, the applicator 10 is comprised of a tubular support 11 opened at the bottom (as viewed in the drawing), a shock wave generator 12, and an expandable rubber bag container 13. The generator 12 is shaped like a spherical shell having a plurality of ring-shaped piezoelectric elements of different diameters which are concentrically arrayed. The generator 12 is mounted on the support 11, closing the opening of the support 11. The rubber bag container 13 includes a bellows 14 and a contact thin film 15, which comes in contact with the body surface of a patient 21 on a bed 20 when he takes medical treatment. The top of the bellows 14 is located in the front of the shock wave generator 12, and is supported by the support 11. The contact thin film 15, as a rubber film, for example, is fixed to the bottom of the bellows 14. The inside of the container 13, viz., a space defined by the shock wave generator 12, bellows 14, and contact film 15, is filled with a liquid medium 16 allowing a shock wave to propagate. The liquid 16 is preferably degased water. When treatment is made, an operator, e.g., a doctor, instructs emission of a shock wave on a console 18. By the instruction, a drive circuit 17 is driven to apply a pulse voltage to the shock wave generator 12. In response to the pulse, the shock wave generator 12 generates or emits a shock wave. The shock wave propagates through the liquid medium 16 and the contact film 15, and hits a calculus 22 in a human body of the patient 21. The support 11 is coupled with an applicator locater 24 by means of a support arm 23. In response to an instruction entered from the console 18, the locater 24 vertically moves the applicator 10 as in the direction of arrow. One end of a pipe 25 is communicably joined with the rubber bag 13. The pipe 25 is bifurcated at the middle into branch pipes 25A and 25B by means of a branching means 26. A drain pump 27 and a feed water pump 28 are inserted in the branch pipes 25A and 25B, respectively. The ends of the branch pipes 25A and 25B, which are respectively opposite to those connecting to the branching means 26, are communicably coupled with a tank 29. The tank 29 stores the degased water as the medium liquid 16. A pressure transfer pipe 30 is communicably connected at one end with the top of the rubber bag container 13, while is connected at the other end with a pressure sensor 31. The pressure sensor 31 generates an electrical signal whose amplitude depends on pressure within the pipe 30, viz., pressure within the container 13. The pressure sensor 31 may be any suitable known semiconductor pressure sensor. An output signal of the sensor 31 is digitized by an A/D converter (ADC) 32, and is applied to a CPU (central processing unit) 33. The CPU 33 compares an output digital signal of the ADC 32 (which is indicative of a pressure sensed by the sensor 31). On the basis of the comparison result and the on- and off-states of the pumps 27 and 28, the CPU 33 drives through an interface 34 pump drivers 35 and 36 for driving the drain pump 27 and the feed water pump 28. A control flow of the CPU 33 is as illustrated in Fig. 2. At the start of treatment, the CPU 33 fetches pressure data collected by the sensor 31, that is, reads a digital signal outputted from the ADC 32 (step S1). In step S2, the CPU 32 checks if the pressure data > a preset value. When the answer is YES, the CPU checks the feed water pump 28 is operating or in an on state, in step S3. Of course, the CPU 33 has known the present state of the pump 28, on- or off-state. If the pump 28 is in an on state, the CPU 33 stops a signal supplied to the pump driver 36 and turns off of the pump 28, in step S4. Then, it proceeds to step S5. In step S5, the CPU 33 sends a signal to the pump driver 35, to turn on the drain pump 27. In the next step S6, the CPU 33 reads a pressure sensed by the pressure sensor 31 as in step S1, and checks if the pressure is greater than the preset value, in step S7. If the answer is YES, the CPU 33 returns to step S6. If NO, it goes to step S8. In this step, the CPU 33 stops the signal to the pump driver 35, thereby to turn off the drain pump 27. After departing from step S8, the CPU 33 returns to step S1, and repeats the similar sequence of processings. An operation of the apparatus for disintegration of calculuses thus arranged will be described with reference to Figs. 3A through 3D. Fig. 3A shows a variation of pressure "P" within the container 13 that is sensed by the sensor 31; Fig. 3B, a variation of height "H" of the contact film 15; Fig. 3C, on- and off-states of the drain pump 27; Fig. 3D, on- and off-states of the feed water pump 28. Returning to Fig. 1, there is illustrated how to disintegrate the renal calculus 22 by using the calculus disintegrating apparatus under discussion. As shown, the patient 21 lies on his face on the bed 20. The applicator 10 is previously positioned above a kidney of the patient 21 by the applicator locater 24. Before treatment, the contact thin film 15 is not in contact with the patient 21. Under this condition, a space is created under the contact thin film 15. Accordingly, the pressure sensor 31 detects a negative pressure. This state continues till time point t1 where the applicator 10 is dropped by the locater 24 and comes in contact with the patient 21. When the contact film 15 contacts the patient 21 at time t1, the pressure within the container 13 as being detected by the sensor 31 gradually increases, and reaches a preset value "X" at time t2. The preset value "X" is a pressure, i.e., 0 kg/cm², at which the patient 21 begins to uncomfortably feel the pressure applied from the applicator 10 or to feel the weight of the medium liquid 16. When the pressure reaches the preset value "X" at time t2, the CPU 33 operates the drain pump 27 to cause it to start drainage of the liquid 6 from the rubber bag container 13 to the tank 29. Then, the pressure in the container 13 gradually decreases. At time t3, the pressure drops below the preset value "X", the CPU 33 stops the drain pump 27 again. As the result of such operation, the patient 21 little feels the weight of the applicator 10, and may undergo comfortable treatment. At time t4, in response to an instruction by an operator, the applicator locater 24 is driven and the applicator 10 starts to lift. At time t5, the contact film 5 disengages from the patient 21, and at time t6, the operator enters an instruction of starting up the feed water pump 28 from the console 18. In turn, the the pump 28 starts up its operation, and starts to supply the liquid 16 to the container 13. Accordingly, the pressure within the container 13 starts to increase. When a proper amount of the liquid 16 is reached within the container 13, the operator enters an instruction to stop the pump 28. Accordingly, such pressure as to make the patient irritative or uncomforted will never be applied to the patient. When the pump stop instruction is not entered, the increase of the container pressure continues and at time t7, the pressure exceeds the preset value "X". The excessive pressure is applied through the sensor 31 and the ADC 32 to the CPU 33. In turn, the CPU 33 turns on the drain pump 27 again, to reduce the pressure within the container 13. In this case, if the feed water pump 28 is turned off at this time t7, a time that the patient feels the pressure from the applicator 10 is reduced, and the reduction of the patient's pressure feeling time brings about better results. In this way, the CPU 33 turns on the drain pump 27 when the pressure within the container 13 is an excess of the preset value "x", and turns off the pump 27 when the pressure is below the preset value. When the pressure > the preset value, if the feed water pump 28 is operating, the CPU 33 turns on the drain pump 27 while at the same time turns off the feed water pump 28. Through the controls by the CPU, the patient 21 may undergo treatment while being free from the uncomfortable pressure from the applicator 10. Further, the applicator locater 24, for example, is mistakenly operated or improperly operates, the patient 21 can be protected from the resultant danger. With the control by the CPU, the positioning of the applicator 10 by the operator and the adjustment of the amount of the medium liquid 16 in the container are made easy. Although the operator is under continuing pressure to keep the pressure applied from the applicator to the patient 21 below a preset value, the present invention releases the operator from such mental strain. In this embodiment, the CPU 33 generates an alarm signal 37 during a period that the pressure sensed by the sensor 31 is above the preset value. The alarm signal 37 is sent to the console 18, and is visually presented by a display 14 on the console 18. The alarm may be generated acoustically by means of a speaker. From the alarm, the operator recognizes that the uncomfortable pressure is being applied to the patient 21 and may enter a proper instruction on the console. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices, shown and described herein. Accordingly, various modifications may by without departing from the pirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims: An apparatus for disintegrating calculuses (22) such as calculuses in a human body of a patient (21) with shock waves, the apparatus comprising a shock wave generator (12) which generates shock waves which propagate through a liquid medium (16) in an expandable container (13), said liquid medium (16) allowing the shock wave to propagate therethrough and being fed from storage means (29), means (23,24) for vertically moving said shock wave generator (12) and said container (13) above said patient (21), pressure detecting means (30 to 32) for detecting the pressure in said container (13), liquid control means (25 to 27, 33 to 35), which, when the detected pressure exceeds a preset value, drains said liquid medium (16) from said container (13) to said storage means (29) until said detected pressure drops below said preset value, and means (33,19) for generating an alarm signal (37) during a period that said detected pressure exceeds said preset value. The apparatus according to claim 1, characterized in that said shock wave generator (12) contains a piezoelectric element, said element producing a shock wave in response to a pulse voltage. The apparatus according to claim 1, characterized in that said container (13) includes a bellows (14) whose opening is closed by said shock wave generator (12), and a contact film (15) which comes in contact with the body surface of said patient (21) to close another opening of said bellows (14). The apparatus according to claim 1, characterized in that said pressure detecting means includes a pressure transfer pipe (30) communicably coupled at one end with the top surface of said container (13), and a pressure sensor (31) coupled with the other end of said pipe (30) for producing an electric signal in accordance with pressure in said container (30). The apparatus according to claim 1, characterized in that said liquid control means (25 to 27, 33 to 35) stops the supply of said liquid medium (16) when said detected pressure exceeds a preset value during the supply of said liquid medium (16) from said storage means (29) to said container (13). The apparatus according to claim 5, characterized in that said liquid control means includes a pipe (25) coupled at a first end with said container (13) and bifurcated at the middle of said pipe into two branch pipes (25A, 25B) whose second ends are coupled with said storage means (29), a first pump inserted in one (25A) of said branch pipes (25A, 25B) and for draining said liquid medium (16) from said container (13) into said storage means (29), and a second pump (28) inserted in the other branch pipe (25B) and for supplying said liquid medium from said storage means (29) into said container (13). The apparatus according to claim 6, characterized in that when said detected pressure exceeds said preset value, pump control means (33 to 36) turning on said first pump (27) till said detected pressure drops below said preset value, and when said detected pressure exceeds said preset value during the on-state of said second pump (28), said pump control means (33 to 36) starting up said first pump (27).

Inventors: OGURA ICHIRO, OGURA, ICHIRO, OGURA, ICHIRO, C/O INTELLECTUAL PROPERTY DIVISION
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1990
Main classification: A61B17
IPC codes: A61B18, A61B17