Abstract:
A cautery apparatus and method are provided that coagulate tissue along a seam and near the ends of the seam. The cautery apparatus and method include a cautery device and an EMG system. When a set of electrodes for the EMG are placed in the lower extremities of a patient, the cautery method injects a current at the cautery device and monitors the EMG electrodes. When nerve stimulation is detected at the EMG electrodes, during tissue coagulation, the position of the cautery device is changed. Generally, the cautery device is repositioned to eliminate nerve stimulation, thereby avoiding nerve damage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority benefit from U.S. Provisional Patent Application No. 61/649,701 filed on May 21, 2012, and U.S. Provisional Patent Application No. 61/709,442 filed on Oct. 4, 2012. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates generally to surgical coagulation tools and nerve detection during surgical coagulation. 
       BACKGROUND 
       [0003]    Various surgical tools are available for coagulation or cauterization of tissue. The general, prior art designs include a set of electrodes to which a current is applied. In a monopolar configuration, one electrode is placed against the tissue of interest and the current is returned at a distant electrode. In a bipolar configuration, two local electrodes are placed against the tissue of interest and the current flows between the two electrodes. 
         [0004]    Referring to  FIG. 1 , prior art cautery devices generally require a set of wire frame electrodes at the tip. The geometry of the wire frame electrodes is necessitated by a suction hole  105  through which burned material is removed. Cautery probe  101  includes electrode  102  and electrode  103  which are insulated so that electrode  102  and electrode  103  are not in electrical contact. 
         [0005]    Referring to  FIG. 2 , switching for a prior art cautery device is shown. Coagulation current source  204  is connected at a first electric potential to switch  205  which is further connected by a conductor  207  to electrode  102 . Coagulation current source  204  is connected at a second electric potential to switch  206  which is further connected by a conductor  209  to electrode  103 . Switch  205  and switch  206  are SPST (single pole single throw) normally-open switches. 
         [0006]    In operation, the prior art cautery device is placed in contact with tissue. Switch  205  and switch  206  are then closed to energize an electric potential difference between electrode  102  and electrode  103 . The electric potential difference initiates a current flow from electrode  102  to electrode  103  through the tissue. 
         [0007]    U.S. Pat. No. 6,109,268 to Thapliyal et al. discloses an electrosurgical probe that has a tip region which comprises electrode terminals designed to deliver electrical energy in the vicinity of the tip. The return electrodes may comprise a single tubular member of conductive material proximal to the electrode terminals. 
         [0008]    U.S. Patent Application Publication No. 2012/0089141 to Lee et al. discloses an electrode body which is flexible and includes a first electrode, an insulator, and a second electrode. A process is disclosed including detecting a nerve responsible for pain and ablation of tissue with electrocautery. 
         [0009]    U.S. Pat. No. 7,693,562 to Marino et al. discloses a probe which includes electrodes which may detect an EMG response to detect a nerve. 
         [0010]    In U.S. Patent Application Publication No. 2010/0152726 to Cadouri et al., an electrosurgical system with selective control of active and return electrodes is disclosed. The electrosurgical system comprises a wand and a controller. The controller comprises a non-conductive outer surface, at least three electrodes disposed on a distal end of the wand and at least three electrical leads extending from a proximal end of the wand. A control circuit is configured to selectively activate the electrodes. 
       SUMMARY 
       [0011]    Disclosed is a system and method for cauterizing tissue in tightly constrained surgical situations. The system generally includes several electrodes attached to a cautery probe in a unique geometry. Two of the electrodes are co-planar and are of a semicircular shape. The cautery probe also includes annular electrodes adjacent the co-planar electrodes. The arrangement of the probes creates a variable electric field which allows focused cauterization energy that can be changed during use. 
         [0012]    The system includes a power source for supplying an electric current to the electrodes through a set of switches. The cautery system can include an automatic controller operatively connected to the set of switches to set them. 
         [0013]    In another aspect, the system is provided with an electromyograph connected to the controller to detect nerve responses to the cautery probe. The controller is programmed to determine if a response is received from the electromyograph when the probe is utilized. If a response is received, then the controller causes an alert signal. If a response is not received, then the controller initiates cauterization current flow. 
         [0014]    A preferred method is also disclosed. The method provides for iterative energization of a set of current pulses to flow to the electrodes if a response signal is not received from the electromyograph within a predetermined time period. 
         [0015]    In another aspect, the method additionally provides the cautery probe with a controller responsive to the electromyograph. The controller is configured in an idle state wherein the first electrode and the second electrode are not energized. The controller is then configured in a test state which iteratively energizes the set of current pulses and determines if the response signal is received from the electromyograph within a predetermined time from the beginning of each iteration. If the response signal is received within the predetermined time, then the method continues by iteratively energizing the set of current pulses and determining if the response signal is received. If the response signal is not received within the predetermined time, then the method continues by energizing the coagulation current. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]    The disclosed inventions will be described with reference to the following drawings: 
           [0017]      FIG. 1  is a schematic representation of a cauterization probe of the prior art. 
           [0018]      FIG. 2  is a circuit diagram of a cauterization probe of the prior art. 
           [0019]      FIG. 3  is a schematic representation of a preferred embodiment of the cautery system. 
           [0020]      FIG. 4  is a perspective view of a preferred embodiment of a cautery device. 
           [0021]      FIG. 5  is a circuit diagram of a preferred embodiment of a switching circuit for a cautery device. 
           [0022]      FIG. 6  is a perspective view of an alternate embodiment of a cautery device. 
           [0023]      FIG. 7  is a circuit diagram of an alternate embodiment of a switching circuit for a cautery device. 
           [0024]      FIG. 8  is a block diagram depicting a system for nerve detection during coagulation using a preferred embodiment of the cautery device. 
           [0025]      FIG. 9  is a schematic representation of a preferred embodiment of a cautery device including an integrated electromyograph. 
           [0026]      FIG. 10  is device state diagram for a preferred embodiment of a preferred embodiment of a cautery device including an integrated electromyograph. 
           [0027]      FIG. 11  is a flow diagram for a preferred embodiment of a method for testing and coagulation. 
           [0028]      FIG. 12  is a flow diagram for a preferred embodiment of a method for coagulation. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Referring to  FIG. 3 , a block diagram of a preferred embodiment of a cautery system is described. Cautery system  300  includes a cautery probe  301  for coagulating tissue, a switching circuit  303  connected to cautery probe  301 , a power source  304  connected to switching circuit  303  for powering the cautery probe and controller  305  for controlling the switching circuit  303 . 
         [0030]    In one embodiment, controller  305  is a mechanical control such as a resilient button connected to a switch. In another embodiment, controller  305  is an electronic controller. The switch states are set by applying an electrical signal through the electronic controller. 
         [0031]    Cautery probe  301  further comprises a state indicator  306 . State indicator  306  is provided in the cautery system to indicate an operational state as selected by controller  305 . State indicator  306  is any device or combination of devices configured to alert a user of the system state. For example, state indicator  306  is configured to control a set of indicator LEDs or a piezoelectric speaker for generation of an audible tone. 
         [0032]    In a preferred embodiment, the cautery probe can include a housing or handle encapsulating the switch, the control and the state indicator connected by a set of wires to an external power source. In another embodiment, the switch, the control, the state indicator and the power source are housed separately from the cautery probe. 
         [0033]    In other preferred embodiments, controller  305  may be implemented entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) or combining software and hardware implementation that may all generally be referred to herein as a “circuit,” “module,” “component,” or “system.” Further, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable media having computer readable program code embodied thereon. 
         [0034]    Any combination of one or more computer readable media may be utilized. The computer readable media may be a computer readable signal medium or a computer readable storage medium. For example, a computer readable storage medium may be, but not limited to, an electronic, magnetic, optical, electromagnetic, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include, but are not limited to: a portable computer diskette, a hard disk, a random access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or Flash memory), an appropriate optical fiber with a repeater, a portable compact disc read-only memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. Thus, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
         [0035]    A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. The propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable signal medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, or any suitable combination thereof. 
         [0036]    Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python or the like, conventional procedural programming languages, such as the “C” programming language, Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages such as Python, Ruby and Groovy, or other programming languages. 
         [0037]    Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable instruction execution apparatus, create a mechanism for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0038]    These computer program instructions may also be stored in a computer readable medium that when executed can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions when stored in the computer readable medium produce an article of manufacture including instructions which when executed, cause a computer to implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer, other programmable instruction execution apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatuses or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0039]    Referring to  FIG. 4 , a first embodiment is shown. Cautery probe  410  is comprised of an elongated shaft  408  made of a disposable rigid plastic such as Dacron®, Teflon®, or polyvinyl chloride. More durable materials may be employed such as porcelain and other non-conductive ceramic materials. Stainless steel may also be employed for the shaft, but the electrodes must be insulated from the shaft. Cautery probe  410  includes three electrodes disposed on distal end surface  409 . Electrode  411  and electrode  412  are each a semicircular “D” configuration. In the preferred embodiment, the electrodes are diametrically opposed, and set in the same plane, generally perpendicular to the longitudinal axis of the probe. In another preferred embodiment, the electrodes are set in the same plane; but, the plane is set at an oblique angle, such as 30°, 45°, 60°, to the longitudinal axis of the probe. Each of the electrodes is composed of polished stainless steel, embedded in the distal end of the probe during manufacture. Alternatively, the electrodes can be affixed with an epoxy adhesive. 
         [0040]    Ring electrode  413  is disposed on radial surface of shaft  408 . Ring electrode  413  is located adjacent to and proximate electrodes  411  and  412  and forms an annular band surrounding the probe. In a preferred embodiment, the ring electrode is made of polished stainless steel and is embedded in the surface of the probe. 
         [0041]    Electrodes  411  and  412  are separated from each other by insulating gap  414 . Ring electrode  413  is separated from electrodes  411  and  412  by insulating gap  415 . Gaps  414  and  415  serve to insulate electrodes  411 ,  412  and ring electrode  413  from one another and from shaft  408 . 
         [0042]    Referring to  FIG. 5 , switching circuit  500  is disclosed. Switching circuit  500  employs three SPDT (single pole double throw) normally-open switches, switch  505 , switch  506  and switch  507 . Power supply  504 , connected to switching circuit  500 , supplies an electric current across power terminals  515  and  516 . In another preferred embodiment, the three SPDT switches are operable as momentary switches in one of several fixed states. In a preferred embodiment, the three SPDT switches are transistor based relays responding to the controller. In an alternate embodiment the three SPDT switches are mechanical. 
         [0043]    Switch  505  includes terminal  525  connected to electrode  411 , terminal  526  connected to terminal  531  of switch  506  and terminal  527  connected to power terminal  515 . Terminal  526  is further connected to power terminal  515 . In a first position of switch  505 , terminal  525  is connected to terminal  526 . In a second position of switch  505 , terminal  525  is connected to terminal  527 . 
         [0044]    Switch  506  includes terminal  530  connected to electrode  412 , terminal  531  connected to terminal  526  of switch  505  and terminal  532  connected to power terminal  516 . In a first position of switch  506 , terminal  530  is connected to terminal  531 . In a second position of switch  506 , terminal  530  is connected to terminal  532 . 
         [0045]    Switch  507  includes terminal  540  connected to ring electrode  413 , terminal  541  connected to power terminal  516 , and floating terminal  542  which is normally unconnected. In a first position of switch  507 , terminal  540  is connected to terminal  541 . In a second position of switch  507 , terminal  540  is connected to floating terminal  542 . 
         [0046]    In a preferred embodiment, there are two selectable modes of instantaneous operation, “tip” mode and “ring” mode. 
         [0047]    To enable the “tip” mode, terminal  525  is connected to terminal  527 , terminal  530  is connected to terminal  532  and terminal  540  is connected to floating terminal  542 , thereby sending current across electrodes  411  and  412 . Alternatively, terminal  507  can be left in its normally open state. In the “tip” mode, tissue is cauterized between electrodes  411  and  412 . 
         [0048]    To enable the “ring” mode, terminal  525  is connected to terminal  526 , terminal  530  is connected to terminal  531  and terminal  540  is connected to terminal  541  thereby connecting electrodes  411  and  412  together to power terminal  515  and connecting ring electrode  413  to power terminal  516 . The “ring” mode results in a current across ring electrode  413  and electrodes  411  and  412 . In the “ring” mode tissue is cauterized at the side of the cautery probe, between ring electrode  413  and either electrode  411  or electrode  412 . 
         [0049]    Referring to  FIG. 6 , a second preferred embodiment is described. Cautery probe  610  is comprised of an elongated shaft  608  made of a disposable rigid plastic such as Dacron®, Teflon®, or polyvinyl chloride. More durable materials may be employed such as porcelain and other non-conductive ceramic materials. Stainless steel may also be employed for the shaft, but the electrodes must be insulated from the shaft. Shaft  608  has a generally cylindrical surface and distal end  609 . Electrode  611  and electrode  612  are disposed on distal end  609 . Electrode  611  and electrode  612  are semicircular “D” shaped and are diametrically opposed from each other. Electrode  611  and electrode  612  are co-planar and are generally perpendicular to the longitudinal axis of the shaft. Electrode  613  is disposed on shaft  608  adjacent electrode  612 . Electrode  614  is disposed on the shaft  608  adjacent to electrode  609 . Each electrode  613  and  614  is semi-annular. The electrodes are diametrically opposed. Holes  618  are provided for a supply of irrigation fluid. 
         [0050]    Electrodes  611  and  612  are insulated from each other by gap  615 . Electrodes  613  and  614  are electrically insulated from electrodes  611  and  612  by gap  616  and from each other by gap  617  and a similar gap (not shown) diametrically opposed to gap  617 . 
         [0051]    Referring to  FIG. 7 , a preferred embodiment of switching circuit  700  is described. Switching circuit  700  employs three SPST (single pole single throw) normally-open switches, switch  705 , switch  706  and switch  707 . Power source  704 , connected to switching circuit  700 , supplies an electric potential difference across power terminals  730  and  731 . In a preferred embodiment, the switches are mechanical momentary switches. Switches  706  and  707  may be configured to open and close in tandem. 
         [0052]    In an alternate embodiment, the switches are transistor based relays operated by the controller. In one embodiment, all switches are capable of independent closure. In another embodiment, switches  706  and  707  are mechanically linked and close and open at the same time. 
         [0053]    Switch  705  includes terminal  735  connects to terminal  730  and terminal  736  to electrode  611 . Electrode  612  is directly connected to power terminal  731 . Switch  706  connects terminal  740  to electrode  613  and terminal  741  to terminal  736 . 
         [0054]    Switch  707  connects terminal  745  to electrode  614  and terminal  746  connected to electrode  612 . 
         [0055]    When switch  705  is closed, electric current is supplied to electrode  611  and terminal  741  of switch  706  and returned through electrode  612 . In the open state of switch  705 , no electric current flows through any of the electrodes  611 ,  612 ,  613  or  614 . 
         [0056]    In the closed state of switch  706 , electrode  611  is connected to electrode  613  and electric current is allowed to flow from power source  704  to electrode  613  based on the state of switch  705 . In the open state of switch  706  no electric current flows to electrode  613 . 
         [0057]    In the closed state of switch  707 , electrode  612  is connected to electrode  614  and electric current is allowed to return to power source  704  from electrode  614  based on the state of switch  705 . In the open state of switch  707  no electric current is returned from electrode  614 . 
         [0058]    The selectable modes offer different cauterization field patterns that are related to the geometry of the tip and are novel and highly useful in certain surgical situations. For example, when only switch  705  is closed, a “tip” mode is created in which a field is provided directly ahead and perpendicular to the shaft. The mode is useful in cauterizing vessels as the tip is pressed against them longitudinally, preventing blood flow. When switches  705  and  706  are closed simultaneously, a cauterization field is produced which is biased toward the tip and the right side of the end of the probe. This mode is called the “tip right” mode. It is useful in tight surgical situations where cauterization must occur beside the probe but reorientation is not possible. In a similar way, when switches  705  and  707  are closed, a field is produced that is biased toward the tip and the left side of the probe. This mode is called the “tip left” mode. 
         [0059]    Finally, when switch  705 ,  706 , and  707  are closed simultaneously the probe is placed in “side” mode. In side mode, coagulation can occur circumferentially at the side of the probe tip, perpendicular to the long-axis of probe  608 . This mode is useful in situations where coagulation is desired on the side-wall of a tightly constrained surgical filed. 
         [0060]    Referring to  FIG. 8 , a block diagram of a combined cautery and nerve detection system is shown. In a preferred embodiment, a cautery device  802  is applied to cauterize and coagulate a wound area  804  on patient  801 . A set of EMG electrodes  806  is connected to another area  805  of patient  801  and further connected to an electromyograph system  803  for detecting nerve activity. Electromyograph system  803  is also in communication with cautery device  802 . The presence of an electromyograph provides an opportunity for nerve detection to reduce or eliminate the possibility of inadvertent nerve damage during coagulation. 
         [0061]    Referring to  FIG. 9 , a detailed diagram of a preferred embodiment of the combined cautery and nerve detection system is described. Combined system  900  includes a cautery probe  901  having a set of electrodes  902  and a state indicator  906 , a switching circuit  903  connected to cautery probe  901 , a power source  904  connected to switching circuit  903  for powering the cautery probe, a controller  910  for automatically controlling the state of the switching circuit and for communications with electromyograph system  912  and a control  905  for user interaction with the combined system. 
         [0062]    Combined system  900  further comprises electromyograph system  912  having a set of EMG electrodes  913  for placement at a known responsive area of a patient. Electromyograph system  912  and set of EMG electrodes  913  are configured to detect electrical response to nerve excitations in the vicinity of a tissue surface interacting with the cautery probe. Electromyograph system  912  is in communication with controller  910  over a link  911  to indicate detection of the nerve excitations. 
         [0063]    Control  905  is provided to change the state of switching circuit  903  thereby changing the system state. Control  905 , for example, can be as simple as an on/off button or include a set of buttons. Additionally, state indicator  906  is provided to indicate a system state. 
         [0064]    In a preferred embodiment, set of electrodes  902  comprise a set of end electrodes and a set of ring electrodes, as previously disclosed. 
         [0065]    In a preferred embodiment, controller  910  comprises a processor, such as a microcontroller, and memory. However, controller  910  can be any electrical circuit capable of changing the state of the switching circuit and responding to communications from the electromyograph system, such as a digital state machine. For example, controller  910  can be a discrete electronic circuit or a programmable logic device such as an ASIC or FPGA. 
         [0066]    State indicator  906  is any device or combination of devices configured to alert a user of the system state. For example, state indicator  906  is configured to control a set of indicator LEDs or an auditory speaker. 
         [0067]    Link  911  is any communications link compatible with electromyograph system  912 . In one example, link  911  can be a proprietary wired or optical connection. In another example, link  911  can be a wireless connection such as a Bluetooth link. 
         [0068]    In another embodiment, controller  910  and switching circuit  903  are combined as a single circuit. 
         [0069]    Referring to  FIG. 10 , a state diagram for the combined cautery and nerve detection system is disclosed. The cautery system begins in a “standby” state  1001  until moved into the “coagulate” mode  1003  or into a “test and coagulate” mode  1002 . In “coagulate” mode  1003 , cauterization current is applied to the desired electrodes as long as the set of switches is actuated by the control. In “test and coagulate” mode  1002 , the set of switches are momentarily actuated to issue a test pulse to the coagulation electrodes. An absence of electromyographic response is awaited from the electromyographic system prior to energizing the coagulation current. Coagulation current is withheld if there is synchronous nerve activity detected. If no nerve activity is detected then the coagulation current is applied for a specified duration until another test pulse is delivered or the user returns the system to standby state  1001 . 
         [0070]    In use, the system states are traversed by depressing or releasing the various switches. For example, a user presses a switch to cause the test pulse and manually await the electromyographic response. The user then applies the coagulation current if no nerve activity is detected. 
         [0071]      FIG. 11  shows a flowchart for the “test and coagulate” mode  1002 . At step  1101 , the control is operated, for example, by depressing a momentary button switch. At step  1102 , the controller checks the switch for a closed condition. If the switch is open, then the system returns to standby state  1001 . If the switch is closed, then the method moves to step  1104 . At step  1104 , a stimulating current pulse is sent through electrodes  411  and  412 , for tip mode or electrodes  411 ,  412 , and  413  for side mode, or alternatively, electrodes  611  and  612  for tip mode or electrodes  611 ,  612 ,  613  and  614  for side mode. At step  1105 , electromyograph is signaled to start detection. Step  1106  implements a time delay after the electromyograph is signaled. In the preferred embodiment, the time delay is about 100 ms. The time delay may be varied. At step  1107 , the electromyograph is queried for detection of nerve activity. 
         [0072]    If nerve activity is detected, then at step  1108 , a warning message is sent and the method returns to step  1101 . The warning message can be, for example, a light activated by the state indicator or a warning sound emitted from a speaker. 
         [0073]    If nerve activity is not detected, then at step  1109 , the cautery device energizes coagulation current from at least one of the “tip” mode and the “ring” mode as selected by the control. Step  1110  implements a time delay. At step  1111 , the coagulation current is turned off and the method repeats at step  1102  for a different position of the cautery device. 
         [0074]    At step  1109 , the state indicator can be additionally programmed to indicate that coagulation occurs, for example, by activating a light or by emitting a sound. 
         [0075]      FIG. 12  demonstrates a flow chart for the “coagulate” mode  1003 . At step  1215 , the “coagulate” mode is started when the control is operated, for example, a button switch is depressed. At step  1216 , the controller determines if the corresponding switch is still closed. If the switch is closed, then at step  1217 , the cautery device energizes coagulation current “tip” mode or the “side” mode as selected by the control. The method repeats at step  1216 . If the switch is released and open, then in step  1218 , the coagulation current is turned off. The system then returns to step  1215 . 
         [0076]    While the present invention has been described in terms of specific embodiments thereof, it will be understood in view of the present disclosure, that numerous variations upon the invention are now enabled to those skilled in the art, which variations yet reside within the scope of the present teaching. Accordingly, the invention is to be broadly construed and limited only by the scope and spirit of the claims now appended hereto.