Patent Publication Number: US-2021177444-A1

Title: Feedback dependent lithotripsy energy delivery

Description:
RELATED APPLICATION 
     The present application is a Continuation of a U.S. Non-Provisional application Ser. No. 14/486,483, filed Sep. 15, 2014, which claims priority to U.S. Provisional Application No. 61/904,214, filed Nov. 14, 2013, the contents of each of the above-identified applications are herein incorporated by reference in their entirety. 
    
    
     FIELD 
     The present disclosure relates to a medical device and method, and more particularly to a lithotripter for fragmenting stones in a patient&#39;s body and a method for fragmenting stones. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     Lithotripsy is a common method for fragmenting stones, or calculi, in the urinary tract, kidneys, and/or bladder. Most lithotripsy devices use ultrasound, laser, or pneumatic energy sources to fragment such stones into smaller pieces for easier removal from the patient&#39;s urologic system. Typically, the lithotripter includes a shaft connected to an electrically controlled driver or a pneumatic actuator. The shaft is inserted into the patient&#39;s anatomy to a location near the stone, and energy of a determined pattern is sent through the shaft to impact the stone with the shaft to create a jackhammer or drilling effect on the stone. The tip of the shaft typically has a flat surface. The stone fragments are then removed by irrigation and/or baskets, typically through the center of the shaft by suction. 
     Among the literature that can pertain to this technology include the following patent documents and published patent applications: US 2010/0204617; U.S. Pat. Nos. 4,708,127; 5,042,460; 5,192,889; 5,358,466; 6,689,087; 8,038,693; 6,402,046; 7,942,809; US 2003/0222535; and U.S. Pat. No. 8,038,630, all incorporated by reference for all purposes. 
     The tip of the lithotripter shaft typically has a smooth, flat surface. Usage of tips with smooth faces on bladder, kidney, or ureter tissue has been found in studies to be safe against tissue damage or perforation. While providing more protection, however, the smooth, flat tip easily slips off of the stone, which may prolong the stone-breaking procedure as the physician repeatedly tries to contact the stone with the tip. Furthermore, if the physician applies excess pressure to the stone via the tip, the vibration of the shaft is dampened and less effective. Accordingly, there exists a need for an improved apparatus and procedure for fragmenting stones. 
     SUMMARY 
     The present disclosure provides an improved lithotripter that utilizes sensing technology and methods to determine when it is most effective to apply stone-breaking energy through a lithotripsy shaft. 
     Accordingly, pursuant to one aspect of the invention, which may be combined with or separate from other aspects of the invention, there is contemplated a lithotripter that comprises a lithotripsy apparatus for treatment of a urinary tract stone by fragmentation. The lithotripsy apparatus comprises a lithotripsy wave guide shaft configured to transmit an energy form to at least one urinary tract stone and a sensing device configured to provide signal data for determining optimal application of energy by the lithotripsy apparatus during treatment with the lithotripsy apparatus. A processor is configured to collect the signal data. The processor has a control logic configured to determine at least one of the following: a) if the lithotripsy wave guide shaft is in contact with a tissue; b) if the lithotripsy wave guide shaft is in contact with a stone; c) type of stone; d) if a user is applying force in excess of a predetermined threshold; and e) physical characteristics of a stone. 
     Accordingly, pursuant to another aspect of the invention, which may be combined with or separate from other aspects of the invention, there is contemplated a method for providing feedback to a lithotripsy apparatus having a lithotripsy shaft for fragmenting stones. The method comprises sensing an operational parameter and determining whether the operational parameter indicates at least one of the following operational conditions: a) the lithotripsy shaft is in contact with a tissue; b) the lithotripsy shaft is in contact with a stone; c) type of stone; d) amount of force being applied by a user; e) the user is applying force in excess of a predetermined threshold; and f) physical characteristics of a stone. The method further comprises providing feedback to a user regarding the at least one operational condition. 
     The invention may be further characterized by one or any combination of the features described herein, such as: the signal data includes at least one of current, voltage, frequency, resonance energy information, and positional information; the sensing device is at least one of a piezoelectric element, an electromagnetic element, a variable impedance element, an electro-optic element, or a strain element; the apparatus further comprises a display device configured to indicate to a user at least one of: a) whether the lithotripsy wave guide shaft is in contact with a tissue; b) whether the lithotripsy wave guide shaft is in contact with a stone; c) type of stone; d) whether a user is applying force in excess of a predetermined threshold; e) an amount of force effected upon a stone; and f) physical characteristics of a stone; the lithotripsy wave guide shaft has a distal end; the distal end has sharp edges to aggressively break up a stone; the lithotripsy wave guide shaft is straight and rigid; the lithotripsy wave guide shaft is flexible; the lithotripsy apparatus further comprises a lithotripsy driver; the lithotripsy apparatus further comprises a driver housing; the sensing device is coupled with the lithotripsy device; the method further comprises displaying to a user at least one of the following: a) whether the lithotripsy shaft is in contact with a tissue; b) whether the lithotripsy shaft is in contact with a stone; c) type of stone; d) an amount of force effected upon a stone by the user; e) whether the amount of force effected upon a stone by the user is above or below a predetermined threshold; and f) physical characteristics of a stone; the method further comprises determining whether to deliver stone-breaking energy through the lithotripsy shaft, based on the operational condition; the method further comprising determining an amount of stone-breaking energy to deliver through the lithotripsy shaft, based on the operational condition; the method further comprising delivering stone-breaking energy through the lithotripsy shaft; and the step of sensing an operational parameter includes delivering a sensing energy through the lithotripsy shaft, the sensing energy being lesser than the stone-breaking energy. 
     Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1A  is a schematic perspective view of a lithotripter for fragmenting stones, in accordance with the principles of the present disclosure; 
         FIG. 1B  is a perspective view of a piezoelectric stack of the lithotripter of  FIG. 1A , according to the principles of the present disclosure; 
         FIG. 2  is a schematic perspective view of another lithotripter for fragmenting stones, in accordance with the principles of the present disclosure; 
         FIG. 3  is a schematic perspective view of yet another lithotripter for fragmenting stones, in accordance with the principles of the present disclosure; 
         FIG. 4  is a block diagram illustrating a method for fragmenting stones, according to the principles of the present disclosure; 
         FIG. 5A  is a block diagram illustrating a first portion of another method for fragmenting stones, which may be used in conjunction with the method of  FIG. 4 , in accordance with the principles of the present disclosure; and 
         FIG. 5B  is a block diagram illustrating a second portion the method of  FIG. 5A , according to the principles of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. The present invention relates to a lithotripter for fragmenting stones. 
     A lithotripter for fragmenting a stone inside a patient&#39;s body is provided. The lithotripter may include a lithotripsy apparatus for treatment of a urinary tract stone by fragmentation. The lithotripsy apparatus, for example, comprises a lithotripsy wave guide shaft configured to transmit an energy form to at least one urinary tract stone and a sensing device configured to provide signal data for determining optimal application of energy by the lithotripsy apparatus during treatment with the lithotripsy apparatus. A processor is configured to collect the signal data. The processor has a control logic configured to determine at least one of the following: a) if the lithotripsy wave guide shaft is in contact with a tissue; b) if the lithotripsy wave guide shaft is in contact with a stone; c) type of stone; d) if a user is applying force in excess of a predetermined threshold; and e) physical characteristics of a stone. 
     With reference to the figures, wherein like numerals indicate like components, and specifically with reference to  FIG. 1A , an example of a lithotripter in accordance with the principles of the present disclosure is illustrated and generally designated at  10 . The lithotripter  10  may be used for fragmenting stones in a patient&#39;s anatomy, such as in a patient&#39;s urinary tract, bladder, or kidneys. 
     The lithotripter  10  includes a handle  12  that houses a piezoelectric driver  30  (shown in  FIG. 1B ). The driver  30  is connected by a cable  14  to a control console  16 , which may be driven by a foot pedal  18 , by way of example. In this example, the cable  14  is connected to the driver  30  through a proximal end  20  of the handle  12 . A wave guide shaft  22  is connected to a distal end  24  of the handle  12 . 
     The wave guide shaft  22  may be rigid, semi-rigid, or flexible, by way of example. In the example of  FIG. 1A , the wave guide shaft  22  is illustrated as being rigid. The wave guide shaft  22  is provided for transmitting a waveform generated by the driver  30  to at least one stone, such as a urinary tract stone. Thus, the wave guide shaft  22  is configured to transmit an energy form to the urinary tract stone. The wave guide shaft  22  may be partially inserted into the patient through the patient&#39;s urethra or percutaneously by way of an incision through the patient&#39;s skin, by way of example. The waveforms may be delivered to the stone by way of the distal end  26  of the wave guide shaft  22 . The distal end  26  may be pressed up against a stone to create a jackhammer effect on the stone and break up the stone, by way of example. In the illustrated example, the distal end  26  of the wave guide shaft  22  has a plurality of sharp prongs  28  extending therefrom. The sharp prongs  28  may have sharp edges to aggressively break up a stone. The sharp prongs  28  may be tapered, beveled, or a combination of both tapered and beveled, by way of example. The prongs  28  help secure the wave guide shaft  22  to a stone when the lithotripter  10  is being operated. It should be understood, however, that the end  26  could have any shape, such as a smooth, flat surface or a different shape textured surface. 
     Referring now to  FIG. 1B , the driver  30  is illustrated, which is in the form of a piezoelectric stack in this variation. It should be understood that, in this example, the piezoelectric driver  30  is not shown in  FIG. 1A  because the piezoelectric driver  30  is housed in the handle  12  of the lithotripter  10 . The piezoelectric driver  30  is configured to drive the lithotripter  10  when an electric charge is applied to a stack of first elements  32 , which ultimately sends a longitudinal vibration through the wave guide shaft  22  to create a jackhammer effect on a stone when the wave guide shaft  22  is in contact with the stone. 
     A piezoelectric sensor  36  is disposed adjacent to the piezoelectric driver  30 . Both the piezoelectric sensor  36  and the piezoelectric driver  30  are disposed in the handle  12  in this example, and thus, the piezoelectric sensor  36  and the piezoelectric driver  30  are coupled together. The piezoelectric sensor  36  includes a stack of second elements  34  disposed adjacent to the stack of first elements  32 . The piezoelectric sensor  36  is not configured to be energized by an electric energy source like the piezoelectric driver  30 . Rather, the stack of second elements  34  acts as a sensor. For example, when subject to vibration, the second elements  34  will vibrate. The mechanical strain on the second elements  34  created by the vibration may then be measured and converted to an electrical signal. 
     Thus, the piezoelectric sensor  36  is part of a sensing device that is configured to provide signal data based on the mechanical strain and/or vibration of the piezoelectric sensor  36 . The strain and/or vibration of the piezoelectric sensor  36  may be related to the state of the end  26  or other parts of the shaft  22 . In other words, a different state is sensed based on whether the shaft  22  is in contact with a stone or not in contact with a stone; or more specifically, a different vibration or strain is measured based on whether the shaft is in contact with a stone. Similarly, if the shaft  22  is pressed against a stone with excessive force, the sensor  36  may be able to sense the same based on the amount of vibration and/or strain to which the second elements  34  have been subjected. Accordingly, the piezoelectric sensor  36  may be used to determine optimal application of energy by the lithotripsy apparatus  10  during treatment with the lithotripsy apparatus  10 . 
     Though the piezoelectric sensor  36  is illustrated as being discrete from and disposed adjacent to the piezoelectric driver  30  in  FIG. 1B , it should be understood that, in some variations, the piezoelectric sensor  36  and the piezoelectric driver  30  may be a unitary device, wherein the elements of the stack may be used as both the driver and the sensor. In one variation, an extra element  32  of the piezoelectric driver  30  is used as the piezoelectric sensor. Information from the sensor  36  may be either dependent or independent from the stimulating energy. 
     The control console  16  includes a processor configured to collect the signal data regarding an operational parameter, such as current, voltage, or frequency, which could be based on vibration or strain, or other measurable parameters, to determine an operational condition. In some variations, the processor includes a control logic configured to determine at least one of the following operational conditions, based on the measured operational parameter: a) if the wave guide shaft  22  is in contact with a tissue, such as a cavity wall of the patient; b) if the wave guide shaft  22  is in contact with a stone; c) type of stone; d) if a user is applying force in excess of a predetermined threshold; and e) physical characteristics of a stone. The detection of stone contact may indicate that it would be suitable to apply stone-breaking energy to the shaft  22 , and the detection of no stone contact may indicate that it would not be suitable to apply stone-breaking energy to the shaft  22 . Applied force information might be used to adjust the drive frequency, amplitude or other characteristic. Such an adjustment may be made to improve the performance of the lithotripter given the level of applied force, or it may be made to cease supplying the drive energy to reduce or prevent tissue damage. 
     Analysis might be used to determine what kind of stone, or stone hardness, or stone size was encountered, and the lithotripsy energy delivered may then be tailored to provide a better stone-breaking effect based on the stone characteristics detected. For example, the frequency, drive pattern, or modulation might be adjusted based on the information detected. Detection of resonance energy reduction may be used to identify the effect of too much force being applied by the user, thus diminishing the effectiveness of the applied stone-breaking energy. If the force detected exceeds a predetermined threshold, an alert may be provided to the user to reduce the applied force. The predetermined threshold could be any suitable amount, such as, for example, 1500 g. 
     To break up a stone, a high frequency of about 21.4 kHz, square wave 50% duty cycle could be used, with a gating/modulating low frequency of different ranges. For coarse fragmentation and large stones of about 10-20 mm, the low frequency used for gating the ultrasonic frequency could be a sweeping 5-30 Hz. Optionally, for medium size stones of about 5-10 mm, the low frequency range used for gating the ultrasonic frequency could be a sweeping 25-50 Hz. For fine fragmentation and small size stones of about 1-7 mm, the low frequency range used for gating the ultrasonic frequency could be a sweeping 60-90 Hz. The displacement at the end  26  could be about 20 μm for the ultrasonic frequency and about 0.5-2 mm for the mechanical oscillation in an unloaded state (e.g., in free air). 
     The signal data that is provided by the piezoelectric sensor  36  to the processor could include one or more of the following operational parameters: current, voltage, frequency, and resonance energy information. The control console  16  includes a display window  38  configured to indicate to a user one or more of the following operational conditions: a) whether the wave guide shaft  22  is in contact with a tissue, such as a cavity wall; b) whether the wave guide shaft  22  is in contact with a stone; c) type of stone; d) whether a user is applying force in excess of a predetermined threshold; e) an amount of force effected upon a stone; and f) physical characteristics of a stone. 
     In  FIG. 1A , the wave guide shaft  22  is straight and rigid. It should be understood, however, that the wave guide shaft  22  could alternatively be semi-rigid or flexible. 
     The lithotripter  10  may have portions (not shown) forming a lumen or channel through the wave guide shaft  22  for suctioning and/or irrigating a urinary tract. For example, the wave guide shaft  22  may have a lumen formed through the center of the wave guide shaft  22  and extending along the length of the wave guide shaft  22 . In addition, the handle  12  may have openings formed through both the proximal and distal ends  20 ,  24  of the handle  12 . 
     The driver  30  may take on various forms, without departing from the spirit and scope of the present invention. For example, the driver  30  could have ultrasonic and/or sonic driver components, and it need not be solely a piezoelectric driver. Instead, the driver  30  could also comprise electromagnetic coils, such as a voice coil motor, in one variation. In some forms, the driver  30  could be configured to produce a waveform at a frequency that oscillates at a natural frequency, or resonance frequency, of the targeted stone. 
     Referring now to  FIG. 2 , another example of a lithotripter is illustrated and generally designated at  110 . Like the lithotripter  10  hereinbefore described in  FIG. 1A , the lithotripter  110  shown in  FIG. 2  may be used for fragmenting stones in a patient&#39;s anatomy, such as in a patient&#39;s urinary tract, bladder, or kidneys. Similar to the lithotripter  10  shown above, the lithotripter  110  may include a handle  112  that houses a piezoelectric driver (not shown, see  FIG. 1B  for a similar piezoelectric driver  30 ). The driver and handle  112  are connected by a cable  114  to a control console (not shown, see  FIG. 1A  for a similar control console  16 ). In this example, the cable  114  is connected to a proximal end  120  of the handle  112 . A wave guide shaft  122  is connected to a distal end  124  of the handle  112 . 
     The wave guide shaft  122  is illustrated as being flexible, in this example, however, it should be understood that the wave guide shaft  122  could alternatively be semi-rigid or rigid. The wave guide shaft  122  is provided for transmitting a wave form generated by the driver to at least one stone, such as a urinary tract stone. Thus, the wave guide shaft  122  is configured to transmit an energy form to the urinary tract stone. For the case of a flexible wave guide shaft, the energy form transmitted through the shaft to deliver stone breaking energy to a urinary tract stone may preferably be transverse or shear waves. For example, the wave guide shaft  122  may be partially inserted into the patient through the patient&#39;s urethra or percutaneously by way of an incision through the patient&#39;s skin, by way of example. The waveforms may be delivered to the stone by way of the end  126  of the wave guide shaft  122 . The end  126  may be pressed up against a stone to deliver the transverse or shear waves to the stone and break up the stone, by way of example. The end  126  of the wave guide shaft  122  may include a plurality of sharp prongs, as illustrated at reference numeral  28  in  FIG. 1A , a flat surface, or any other desired shape. 
     A sensing device  140  is attached to, or coupled to, the end  126  of the wave guide shaft  122 . The sensing device  140  may be incorporated into, coaxial with, attached to, or coupled in any suitable way to the end  126  of the wave guide shaft  122 . The sensing device  140  could alternatively be attached to another portion of the lithotripter  110 , other than the end  126  of the wave guide shaft  122 . For example, the sensing device  140  could be disposed in the handle  112 . The sensing device  140  could include one or more piezoelectric elements, one or more electromagnetic elements, one or more electro-optic elements, one or more strain elements or strain gauges, a vibration sensor, laser, a Doppler device, a variable impedance element, an electro-optical impedance element, a flow rate sensor, an accelerometer, a shaft displacement sensor, or any other suitable sensing device. 
     The sensing device  140  is configured to provide signal data to the processor, which may be included in the control console  16 , as described above. The sensing device  140  is configured to sense different operational parameters, based on whether the shaft  122  is in contact with a stone or not in contact with a stone. Similarly, the sensing device is configured to sense an operational parameter that may indicate whether the shaft  122  is pressed against a stone with excessive force. Accordingly, the sensing device  140  may be used to determine optimal application of energy by the lithotripsy apparatus  110  during treatment with the lithotripsy apparatus  110 , as described above with respect to the lithotripter  10  of  FIG. 1A . 
     The sensing device  140  may be used to measure movement of the handle  112  to determine the angle and speed of stone penetration. Movement of the shaft  122  inside the handle  112  could be measured, for example. Rate and direction of motion could be measured to determine the forward (axial) speed of movement of the handle  112  or shaft  122 , for example. The orientation of the lithotripter  110  relative to a force sensor can help to determine off-axis forces on the shaft. The sensing device  140  may be used to determine how far into a stone the device  140  is penetrating by observing the force and forward speed of movement of the lithotripsy shaft  122 . Feedback from the sensing device  140  to the user via the control console (similar to control console  16 , but not shown in  FIG. 2 ) would allow for use of optimal operational parameters through refinement of applied energy characteristics to facilitate faster and more complete stone destruction. 
     The sensing device  140  may be used to measure a flow rate of air during use of a suction function. During the case where the suction function is blocked or impeded, an indicator may be sent to control console to indicate to a user that there is a shaft blockage. This indication may trigger to a user to perform a shaft blockage clearing sequence. A shaft blockage clearing sequence may include reversing suction and forcing the shaft blockage free with forced air, for example. An alternative shaft blockage clearing sequence may include indicating to a user to remove lithotripsy apparatus  110  from the patient, pulsing forced air or applying an aggressive vibrational waveform to rattle the shaft blockage loose, for example. 
     Referring now to  FIG. 3 , yet another example of a lithotripter is illustrated and generally designated at  210 . Like the lithotripter  10  hereinbefore described in  FIG. 1A , the lithotripter  210  shown in  FIG. 3  may be used for fragmenting stones in a patient&#39;s anatomy, such as in a patient&#39;s urinary tract, bladder, or kidneys. The lithotripter  210  includes a lithotripsy apparatus  211  that includes a handle  212  and a wave guide shaft  222  extending from the handle  212 . The handle  212  houses a piezoelectric driver (not shown, see  FIG. 1B  for a similar piezoelectric driver  30 ). The driver and handle  212  are connected by a cable  214  to a control console  216 , which may be driven by a foot pedal  218 . In this example, the cable  214  is connected to a proximal end  220  of the handle  212 . The wave guide shaft  222  is connected to a distal end  224  of the handle  212 . 
     The wave guide shaft  222  is illustrated as being straight and rigid, in this example; however, it should be understood that the wave guide shaft  222  could alternatively be semi-rigid or flexible. The wave guide shaft  222  is provided for transmitting a waveform generated by the driver to at least one stone, such as a urinary tract stone. Thus, the wave guide shaft  222  is configured to transmit an energy form to the urinary tract stone. The wave guide shaft  222  may be partially inserted into the patient through the patient&#39;s urethra or percutaneously by way of an incision through the patient&#39;s skin, by way of example. The waveforms may be delivered to the stone by way of the end  226  of the wave guide shaft  222 . The distal end  226  may be pressed up against a stone to create a jackhammer effect on the stone and break up the stone, by way of example. The distal end  226  of the wave guide shaft  222  may include a plurality of sharp prongs, as illustrated as reference numeral  28  in  FIG. 1A , a flat surface, or any other desired shape. 
     The lithotripter  210  may include an independent sheath, such as an access sheath  242 , that is used in conjunction with the lithotripsy apparatus  211 . For example, a physician could place the lithotripsy apparatus  211  inside an access sheath  242  when performing a stone-breaking procedure. Access sheath  242  could be an endoscope, percutaneous nephrolithotomy (PCNL) access sheath, a ureteral access sheath or the like. The access sheath may be provided with a sensing capability. The access sheath may be electrically connected to the lithotripsy apparatus to facilitate communication back to the user via control console  216 . The lithotripsy apparatus  211  could be inserted through a working channel  243  defined by the cylindrical wall of the access sheath  242  to gain access to the stone. The access sheath  242  includes a sensing device  240  disposed circumferentially on a distal end  244  of the access sheath  242 . However, it should be understood that the sensing device  240  could alternatively be disposed in another location of the access sheath  242 , such as in a handle (not shown) of the access sheath  242 . The sensing device  240  may be incorporated into, coaxial with, or attached in any suitable way to the end  244  or another part of the access sheath  242  or another device. The sensing device  240  could include one or more piezoelectric elements, one or more electromagnetic elements, one or more electro-optic elements, one or more strain elements or strain gauges, a vibration sensor, laser, a Doppler device, or any other suitable sensing device. 
     In another variation (not shown), rather than provide the sheath as an access sheath  242 , the sheath bearing the sensing device  240  may be an endoscope, and the sensing device  240  could be a camera with a light, disposed on the distal end of the endoscope. 
     The sensing device  240  may be configured to provide signal data to the processor, which may be included in the control console  216 , as described above. The sensing device  240  may be configured to sense different values of operational parameters including speed of vibration of shaft  222  as well as displacement of shaft  222 , for example, to help determine if shaft  222  is in contact with a stone or not in contact with a stone. Similarly, the sensing device  240  may be configured to sense whether a suction flow rate is slowed or stopped due to blockage from a large stone. Accordingly, the sensing device  240  may be used to determine optimal application of energy by the lithotripsy apparatus  211  during treatment with the lithotripsy apparatus  211 , as described above with respect to the lithotripters  10 ,  110  of  FIGS. 1A and 2 . 
     Referring now to  FIG. 4 , a method for providing feedback to a lithotripsy apparatus having a lithotripsy shaft for fragmenting stones is illustrated in a block diagram and generally designated at  300 . The method  300  includes a step  302  of sensing an operational parameter of the lithotripter system. For example, the step  302  could include sensing a parameter such as strain, vibration, or any other suitable parameter. 
     The method  300  further includes a step  304  of determining whether the operational parameter indicates at least one of the following operational conditions: a) the lithotripsy shaft is in contact with a tissue; b) the lithotripsy shaft is in contact with a stone; c) type of stone; d) amount of force being applied by a user; e) the user is applying force in excess of a predetermined threshold; and/or f) physical characteristics of a stone. 
     The method  300  includes a step  306  of providing feedback to a user regarding the operational parameter or condition that has been sensed or determined. The feedback may be provided by way of the display  38  on the control console  16 ,  216 , through an audio signal, or in any other suitable manner. For example, the step  306  of the method  300  could include displaying to a user at least one of: a) whether the lithotripsy shaft is in contact with a tissue; b) whether the lithotripsy shaft is in contact with a stone; c) type of stone; d) amount of force effected upon a stone by the user; e) whether the amount of force effected upon a stone by the user is above or below a predetermined threshold; and f) physical characteristics of a stone. The user can then determine whether to deliver stone-breaking energy through the lithotripsy shaft, based on the operational condition, and the user can also determine the amount of stone-breaking energy to deliver through the lithotripsy shaft, based on the at least one operational condition. The method could further include delivering stone-breaking energy through the lithotripsy shaft when it is determined that such an energy should be applied. 
     The step  302  of sensing an operational parameter may include delivering a sensing energy through the lithotripsy shaft, wherein the sensing energy is lesser than the stone-breaking energy. For example, the piezoelectric driver  30  may be used to generate a sensing energy for the purposes of measuring the vibration, strain, or other parameter and determining whether the shaft is in contact with a stone or tissue, characteristics of the stone, or the amount of force that is being applied. Thereafter, once it is determined that a stone-breaking energy should be applied, the user can then increase the amount of energy from the sensing level of energy to the stone-breaking level of energy. The sensing energy level is much lower than the stone-breaking energy level, such that the sensing energy is merely used to obtain a measurement of the operational parameter and does little to alter or break up stones or other tissue. The stone-breaking energy is a high level of energy that is sufficient to break up a stone. 
     Referring now to  FIGS. 5A-5B , a more detailed version of a method for providing feedback to a lithotripsy apparatus having a lithotripsy shaft for fragmenting stones is illustrated in a block diagram and generally designated at  400 . The method  400  begins with a step  402  of turning on the lithotripsy system and performing basic console initialization. The method  400  then includes a step  404  of initializing the hand piece and initiating optimum resonance frequency detection. The method  400  includes a step  406  of sweeping through the system&#39;s frequency range, saving feedback data, and identifying the peak feedback response. 
     Once steps  402 - 406  are complete, the method  400  proceeds to a step  408  of determining whether the peak feedback response meets a predetermined minimum requirement for the attached hand piece and shaft performance. If no, the method  400  follows a path  410  to a step  412  that indicates a signal handpiece error. If yes, the method  400  follows a path  414  to a step  416  that indicates that the signal handpiece initialization was successful. The method  400  then proceeds to a step  418 . In some variations, the step  416  could be eliminated, and the method  400  could proceed to step  418  without completing step  416 . 
     In step  418 , the optimum operational frequency is identified, the system is identified as active, and the hand piece is inactive. In step  420 , the footswitch is pressed. The method  400  then proceeds to step  422 , in which the hand piece is put into contact detection mode. For example, in this step  422 , a periodic low power pulse could be applied. The method  400  next proceeds to step  424 , in which it is determined whether a stone contact is detected. If no, the method  400  proceeds along a path  426  back to the step  422 , in which the hand piece is in detection mode. If yes, however, the method  400  proceeds along a path  428  to a step  430  that includes activating the hand piece with an initial (or previous) standard energy pattern and starting the feedback analysis. The standard energy pattern is the low-level sensing energy described above, wherein applying the standard energy level allows the position and other operational conditions to be sensed. 
     Next, the method  400  proceeds to a step  432  in which it is determined whether a stone is detected or whether the footswitch status has changed. If no stone is detected, the method  400  proceeds along a path  434  back to step  422 . If a stone is detected, however, the method  400  proceeds along a path  436  to a step  438 . If the footswitch is released, the method  400  proceeds along a path  440  back to step  418  (or  420 ). 
     In step  438 , the method  400  includes determining whether excessive resonance reduction has occurred or whether excessive force has been detected. If yes, the method  400  proceeds along path  442  to a step  444 , where a signal excessive force warning is activated. From step  444 , the method  400  proceeds along path  446  back to step  432 . If, however, there is no excessive resonance reduction or excessive force, the method  400  proceeds along path  448  to step  450 . 
     In step  450 , the method  400  includes analyzing the feedback for stone type and status (e.g., whether there is contact with a stone). The method  400  then proceeds to step  452  in which the method  400  determines whether to modify the energy pattern. If no, the method  400  proceeds along path  454  back to step  432 . If yes, the method  400  proceeds along path  456  to step  458 . 
     In step  458 , the method  400  includes applying an appropriate hand piece energy pattern. From step  458 , the method  400  proceeds along a path  460  back to step  432 . 
     It should be understood that the methods  300 ,  400  described in  FIGS. 4, 5A, and 5B  are merely examples, and variations may occur without departing from the spirit and scope of the invention, as defined by the claims. Likewise, the specific illustrations of the lithotripters  10 ,  110 ,  210  are examples and are not meant to limit the invention in any way. The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. For example, variations in the various figures can be combined with each without departing from the spirit and scope of the present disclosure. 
     The preferred embodiment of the present invention has been disclosed. A person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention. 
     Any numerical values recited in the above application include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. As an example, if it is stated that the amount of a component or a value of a process variable such as, for example, temperature, pressure, time and the like is, for example, from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in this specification. For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. 
     Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints, the use of “about” or “approximately” in connection with a range apply to both ends of the range. Thus, “about 20 to 30” is intended to cover “about 20 to about 30”, inclusive of at least the specified endpoints. 
     The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. 
     The term “consisting essentially of” to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. 
     The use of the terms “comprising” or “including” describing combinations of elements, ingredients, components or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components or steps.