Abstract:
A method of measuring conditions of an ultrasonic instrument includes providing an ultrasonic instrument that includes an end effector and a waveguide operably coupled to a generator and the end effector. The method involves generating one or more pulses with the generator, transmitting the one or more pulses to one or both of the waveguide and the end effector, generating one or more waves that scatter in an interferential pattern in response to the transmission of the one or more pulses, registering a signal indicative of the interferential pattern, generating an actual interferential pattern based upon the signal, and identifying one or more conditions of the end effector based upon the actual interferential pattern.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to surgical instruments and, more particularly, to methods of measuring conditions of ultrasonic surgical instruments. 
     2. Background of Related Art 
     As an alternative to open instruments for use with open surgical procedures, many modern surgeons use endoscopes and endoscopic electrosurgical apparatuses (e.g., endoscopic or laparoscopic forceps) for remotely accessing organs through smaller, puncture-like incisions. These instruments are particularly suited for use in minimally invasive procedures, such as endoscopic or laparoscopic procedures where patients tend to benefit from less scarring, less pain, and reduced healing time. Typically, the endoscopic forceps is inserted into the patient through one or more various types of cannulas or access ports (typically having an opening that ranges from about five millimeters to about fifteen millimeters) that has been made with a trocar; as can be appreciated, smaller cannulas are usually preferred. 
     Some endoscopic instruments may utilize ultrasound vibrations to effectuate certain medical procedures. In particular, ultrasonic instruments utilize mechanical vibration energy transmitted at ultrasonic frequencies to treat tissue. When transmitted at suitable energy levels, ultrasonic vibrations may be used to coagulate, cauterize, fuse, cut, desiccate, and/or fulgurate tissue to effect hemostasis. 
     An endoscopic forceps that utilizes ultrasound and is configured for use with small cannulas (e.g., cannulas less than five millimeters) may present design challenges for a manufacturer of endoscopic instruments. 
     SUMMARY 
     According to one aspect, a method of measuring conditions of an ultrasonic instrument includes providing an ultrasonic instrument that includes an end effector and a waveguide operably coupled to a generator and the end effector. The waveguide may be curved. The method involves generating one or more pulses with the generator, transmitting the one or more pulses to one or both of the waveguide and the end effector, generating one or more waves that scatter in an interferential pattern in response to the transmission of the one or more pulses, registering a signal indicative of the interferential pattern, generating an actual interferential pattern based upon the signal, and identifying one or more conditions of the end effector based upon the actual interferential pattern. 
     The method may include providing the ultrasonic instrument with one or more sensors in electrical communication with the generator, registering the signal indicative of the interferential pattern with the sensor, and electrically communicating the signal from the sensor to the generator. The method may involve registering the signal for a predetermined time period, wherein the waveguide defines a predetermined length, wherein sound velocity in the waveguide is predetermined, and wherein the predetermined time period is greater than twice the predetermined length of the waveguide divided by the sound velocity in the waveguide. The method may involve sensing the signal with the generator and registering the signal with the generator. 
     One step may include positioning the end effector in contact with tissue, wherein the one or more conditions correspond to the interaction of the end effector and the tissue. The one or more conditions may include temperature, mechanical load, and/or relative positioning of the end effector. Each condition has one or more predetermined interferential patterns. 
     The method may involve adjusting the one or more pulses based upon the one or more conditions. The method may include adjusting the one or more pulses in response to differences between the actual interferential pattern and the one or more predetermined interferential patterns. The method may involve generating a series of pulses with the generator. The method may include providing a memory device operably coupled to the ultrasonic instrument, the memory device including one or more predetermined interferential patterns based upon the one or more conditions and comparing the actual interferential pattern with the one or more predetermined interferential patterns. The method may include calibrating an operating temperature range of the ultrasonic instrument from about room temperature to about three-hundred degrees centigrade. 
     One aspect of the present disclosure provides a method of measuring conditions of an ultrasonic instrument. The method includes the step of providing an ultrasonic instrument including a housing having a shaft extending therefrom, an end effector operably coupled to a distal end of the shaft, a waveguide operably associated with the shaft, and a transducer operably associated with the waveguide. The waveguide defines a predetermined length. Sound velocity in the waveguide is predetermined. The method involves generating one or more pulses with the transducer, transmitting the one or more pulses to the waveguide, registering one or more ultrasound waves reflected by one or both of the waveguide and the end effector in response to transmission of the one or more pulses, generating an interferential pattern of the one or more registered reflected ultrasound waves, and identifying one or more conditions of the end effector based upon the interferential pattern. 
     The method may involve the step of positioning the end effector in contact with tissue. The one or more conditions may correspond to the interaction of the end effector and tissue. The one or more conditions may include temperature, mechanical load, and/or positioning of the end effector relative to the shaft. 
     One step includes registering the one or more ultrasound waves for a predetermined time period that is greater than twice the predetermined length of the waveguide divided by the sound velocity in the waveguide. 
     The method may include the step of generating a series of pulses with the transducer. One step involves adjusting, the one or more pulses based upon the one or more conditions. 
     According to another aspect, the method includes providing a memory device operably coupled to the ultrasonic instrument. The memory device includes one or more predetermined interferential patterns based upon the one or more conditions. One step involves comparing the generated interferential pattern of the one or more registered reflected ultrasound waves with the one or more predetermined interferential patterns. 
     One step may involve calibrating the operating temperature range of the ultrasonic instrument from about room temperature to about three-hundred degrees centigrade. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which: 
         FIG. 1  shows a perspective view of one example of an ultrasonic instrument; 
         FIG. 2  is a block diagram depicting the interaction between an energy source and a transducer assembly of the ultrasonic instrument of  FIG. 1 ; 
         FIG. 3  is a block diagram depicting the transducer assembly of  FIG. 2 ; 
         FIG. 4  shows a perspective view of one embodiment of an ultrasonic instrument in accordance with the principles of the present disclosure; 
         FIG. 5  is a block diagram depicting the operation of the presently disclosed ultrasonic instrument; 
         FIG. 6  shows a depiction of a predetermined interferential pattern in accordance with the present disclosure; and 
         FIG. 7  shows a depiction of an actual interferential pattern produced by the presently disclosed ultrasonic instrument. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Detailed embodiments of the present disclosure are disclosed herein; however, the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. 
     In the drawings and in the descriptions that follow, the term “proximal,” as is traditional, will refer to an end which is closer to the user, while the term “distal” will refer to an end that is farther from the user. 
     With initial reference to  FIG. 1 , an embodiment of an ultrasonic instrument  10  (e.g., a forceps) is shown for use with various surgical procedures and generally includes a housing  20 , a transducer assembly  30 , an energy assembly  40 , a shaft assembly  50 , a waveguide assembly  60 , a trigger assembly  70 , a rotating assembly  80 , and an end effector assembly  90  that mutually cooperate to grasp, seal, and divide tubular vessels and vascular tissue. 
     Ultrasonic instrument  10  is powered by the energy assembly  40  when the energy assembly  40  is operably connected to the ultrasonic instrument  10 . The energy assembly  40  may include one or more batteries  42  and/or one or more electrosurgical cables (not shown) to transfer energy, e.g. voltage from DC and/or AC signals, to the ultrasonic instrument  10 . The ultrasonic instrument  10  may include a smart battery that controls the charge and discharge of its battery cells and communicates with the transducer assembly  30  as illustrated in  FIG. 2 . 
     In embodiments with one or more electrosurgical cables, the ultrasonic instrument  10  is connectable to an external source of electrosurgical energy, e.g., an electrosurgical generator (not shown). One such source of electrosurgical energy is described in commonly-owned U.S. Pat. No. 6,033,399 entitled “ELECTROSURGICAL GENERATOR WITH ADAPTIVE POWER CONTROL.” 
     The transducer assembly  30  includes one or more ultrasonic transducers  30   a  operably coupled to the housing  20 . Each transducer, which may be positioned within the housing  20 , converts the energy transmitted thereto from the energy assembly  40  into high frequency mechanical motion, e.g., ultrasonic vibration. As such, the frequency of the ultrasonic vibration in the one or more transducers is controlled by the frequency of the energy signal, e.g., high voltage AC signal, applied to the one or more transducers. As depicted in  FIG. 3 , this frequency control may be accomplished by a phase-lock loop in the transducer assembly  30 . 
     With reference to  FIG. 1 , the shaft assembly  50 , which may be at least partially disposable, includes a shaft  52  which extends from the housing  20  and defines a central lumen  52   a  therethrough. The central lumen  52   a  receives at least a portion of the waveguide assembly  60  and a drive assembly  54  therein. The drive assembly  54  is operably coupled to the trigger assembly  70  at a proximal end of the drive assembly  54  and is operably coupled to the end effector assembly  90  at a distal end of the drive assembly  54  for operating the end effector assembly  90  upon the actuation of the trigger assembly  70 . 
     The end effector assembly  90 , which may be at least partially disposable, includes a pair of opposing jaw members  92 ,  94 . The first jaw member  92  pivots relative to the second jaw member  94  via the drive assembly  54  upon the actuation of the trigger assembly  70 , positioning jaw members  92 ,  94  between approximated (closed) and unapproximated (open) configurations. Second jaw member  94  defines a channel  94   a  therethrough. 
     With continued reference to  FIG. 1 , the waveguide assembly  60  is positioned within the shaft  52  of the shaft assembly  50  and is configured to receive and transmit the ultrasonic mechanical vibration generated by the one or more transducers. The waveguide assembly  60  includes a waveguide  62  and an ultrasonic treatment member  64  operably coupled to the distal end of the waveguide  62 . The waveguide assembly  60  is at least partially positionable within one or both jaw members  92 ,  94  of the end effector assembly  90 . More particularly, at least a portion of the ultrasonic treatment member  64  is positionable within the channel  94   a  defined by jaw member  94  of the end effector assembly  90 . The ultrasonic treatment member  64  is configured to receive the mechanical vibration from the one or more transducers and transmit the mechanical vibration to treat tissue positioned within end effector assembly  90 . The waveguide assembly  60  may be longitudinally translatable with respect to the end effector assembly  90 . 
     The rotating assembly  80  is operatively connected to the housing  20  and is rotatable in either direction about the longitudinal axis of the shaft assembly  50  to rotate the shaft assembly  50  and the end effector assembly  90  about the longitudinal axis “A” of the shaft assembly  50 . This enables the user to position and re-position the ultrasonic instrument  10  prior to activation and sealing. The rotating assembly  80  is operably coupled to the shaft assembly  50 . A more detailed description of rotating assembly  80  is described in U.S. Pat. No. 7,101,371, entitled “VESSEL SEALER AND DIVIDER” by Dycus et al. 
     The trigger assembly  70  includes an activation trigger  72  for activating energy from the energy assembly  40  and a clamping trigger  74  for operating the end effector assembly  90 . The trigger assembly  70  is operably coupled to the housing  20 . The activation trigger  72  is configured to facilitate the transmission of the energy from the energy source  42  to the one or more transducers upon the actuation thereof. The clamping trigger  74  is configured to move the drive assembly  54  in order to move the opposing jaw members  92 ,  94  between unapproximated and approximated configurations upon the actuation of the clamping trigger  74 . In this manner, the clamping trigger  74  of the trigger assembly  70  is operatively connected to the shaft assembly  50  to impart movement to first and second jaw members  92 ,  94  from an unapproximated (open) position, where the jaw members  92 ,  94  are in spaced relation relative to one another, to a clamping or approximated (closed) position, where the jaw members  92 ,  94  cooperate to grasp tissue therebetween. 
     In use, when the activation trigger  72  is actuated, the energy assembly  40  applies energy, e.g., the high voltage AC signal, to the transducer assembly  30 . The activation trigger  72  may be configured to operate the ultrasonic instrument  10  in multiple modes of operation, including, but not limited to a low-power mode of operation and a high-power mode of operation. As discussed above, the energy is then converted by the transducer assembly  30  and transmitted from the transducer assembly  30  along the waveguide assembly  60  to the end effector assembly  90  in order to treat tissue grasped between the first and second jaws  92 ,  94  with ultrasonic vibrations. 
     One embodiment of an ultrasonic instrument, generally referred to as  100 , is depicted in  FIG. 4 . Ultrasonic instrument  100  is similar to ultrasonic instrument  10  and is described herein only to the extent necessary to describe the differences in construction and operation thereof. In particular, ultrasonic instrument  100  includes a housing  20  having a shaft assembly  50  extending therefrom, an end effector assembly  90  operably coupled to a distal end of the shaft assembly  50 , a waveguide assembly  60  operably associated with the shaft assembly  50 , and a transducer assembly  30  operably associated with the waveguide assembly  60 . The waveguide assembly  60  defines a predetermined length and may be curved. Sound velocity in the waveguide assembly  60  may be predetermined. 
     Ultrasonic instrument  100  also includes one or more sensors  110  secured thereto that are electrically coupled to the transducer assembly  30  (e.g., via a generator  32  including a microcontroller  34  and/or any suitable electrical, mechanical, and/or electro-mechanical device(s) known in the art). With continued reference to  FIG. 4 , a first sensor  110   a  is shown positioned on the shaft assembly  50  and a second sensor  110   b  is shown positioned on jaw member  94  of end effector assembly  90 . The sensors  110  may be positioned on any suitable portion of the ultrasonic instrument  100 . The sensors  110  are configured to obtain data for enabling the generator  32  to determine one or more conditions of the ultrasonic instrument  100 . 
     The ultrasonic instrument  100  may include an internal and/or external memory device  120 . The memory device  120  may include one or more predetermined interferential patterns  200  ( FIG. 6 ) based upon one or more conditions of the end effector assembly  90  and/or the waveguide assembly  60  (e.g., one or more of temperature, mechanical load, and positioning of the end effector assembly  90  relative to the shaft assembly  50 ) and/or may provide space to store data related to the one or more conditions (e.g., an actual interferential pattern  300  produced by the ultrasonic instrument as illustrated in  FIG. 7 ). As such, this embodiment of the ultrasonic instrument  100  enables a user to measure various conditions of the ultrasonic instrument  100 . 
     In operation, one or more pulses “P” are generated with the transducer assembly  30  (e.g., by virtue of the one or more transducers  30   a ; see  FIG. 1 ) as depicted in  FIG. 5 . In embodiments, the generator  32  may be configured to generate and transmit the one or more pulses “P” or a series of pulses “P.” The transducer  30  assembly may generate a series of pulses “P” with the one or more transducers  30   a . The series of pulses “P” may have a frequency of at least about 200 cycles per nanosecond. The pulses “P” may be transmitted to the waveguide assembly  60  and the end effector assembly  90 , for example, with a frequency of 5 MHz, a duration of 3 microseconds, and repetition rate of 4 kHz. However, any suitable frequency, duration, and repetition rate may be utilized. As the pulses “P” propagate or scatter through the waveguide assembly  60  and the end effector assembly  90 , one or more waves “W”, which may be ultrasonic waves, are reflected by one or both of the waveguide assembly  60  and the end effector assembly  90  in response to transmission of the one or more pulses “P.” In this regard, the waveguide assembly  60  and/or the end effector assembly  90  may act collectively, or individually as a resonator to produce “echo” signals of the reflected waves “W.” 
     To this end, pulse duration “t” may be selected to be noticeably shorter than double the length “L” of the resonator (e.g., one or both of the waveguide assembly  60  and end effector assembly  90 ) over the sound velocity V: t=2L/V. In this regard, the pulse repletion rate should be close to the resonant frequency (e.g., V/2L) of the resonator. The changes in the conditions in the end effector assembly  90  result in changes of the resonator properties. In particular, the changes make the resonant frequency deviate from its initial value. Variations of the resonator properties also result in shape changes in the actual interference pattern. For example, where temperature is a condition, then increasing temperature results in a slight change of the distance between scattering points of the propagated waves, resulting in a phase change of the propagated waves. The phase change is manifested by shape changes in the actual interference pattern when comparing the actual interference patterns of the lower and higher temperatures. 
     The sensors  110  collect data representative of the reflection of the one or more waves “W” and transmit the data via one or more signals “S” to the generator  32 . In some embodiments, the generator  32  may also be used as a sensor to collect the data (e.g., by collecting the “echo” signal and converting the energy into an electrical signal). The generator  32  then registers (e.g., via microcontroller  34 ) the data transmitted via the one or more signals “S” and generates an interferential pattern of the one or more reflected waves “W.” Based upon the interferential pattern produced, the generator (e.g., via the microcontroller  34 ) identifies the one or more conditions of the end effector assembly  90  and/or the waveguide assembly  60 . The generator  32  may provide an output (e.g., via a display  36  operatively coupled to the ultrasonic instrument  100 ) of the one or more conditions. The output may be an audible, visual, or tactile signal of the one or more conditions. When the end effector assembly  90  is positioned in contact with tissue, the one or more conditions may correspond to the interaction of the end effector assembly  90  and tissue. 
     Further to the above, the one or more waves “W” may be registered for a predetermined time period (e.g., at least about 200 microseconds) that is greater than twice the predetermined length of the resonator (e.g., the waveguide assembly  60  and/or the end effector assembly  90 ), or portions thereof, divided by the sound velocity in the resonator. 
     Generated interferential patterns of the one or more registered reflected waves “W” may be compared (e.g., via the microcontroller  34 ) with the one or more predetermined interferential patterns stored on the memory device  120 . The pulses “P” may be adjusted in response to differences between one or more generated interferential patterns and one or more predetermined interferential patterns. Each condition of the end effector assembly  90  and/or waveguide assembly  60  may have one or more predetermined interferential patterns. 
     In one mode of operation, the operating temperature range of the ultrasonic instrument  100  may be calibrated from about room temperature to about three-hundred degrees centigrade. 
     In use, the operator of one of the presently disclosed ultrasonic instruments  10 ,  100  receives information about conditions of the ultrasonic instrument, in real-time during operation thereof. For example, when the operator is aware of the temperature of the end effector assembly  90 , the operator can avoid thermal damage of tissue being manipulated by the ultrasonic instrument. 
     With this purpose in mind, the presently disclosed ultrasonic instruments  10 ,  100  may include any suitable number of electrical connections, configurations, and/or components (e.g., resistors, capacitors, inductors, rheostats, etc.), mechanical connections, configurations, and/or components (e.g., gears, links, springs, members, etc.), and/or electro-mechanical connections, configurations, and/or components such that presently disclosed ultrasonic instrument  10 ,  100  may function as intended. 
     While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.