Abstract:
A method of treating tissue of a body during a surgical procedure is provided comprising providing tissue comprising normal tissue and abnormal tissue; inserting at least one temperature indicating device into the tissue with the temperature indicating device comprising an indicator to provide an indication of when a trigger temperature has been attained and a trigger mechanism configured to operate when heated to the trigger temperature and trigger the activation of the indicator; heating the tissue sufficiently to ablate at least a portion of the abnormal tissue; and transferring heat from the tissue to the trigger mechanism, the heat sufficient to heat the trigger mechanism to the trigger temperature and trigger the activation of the indicator.

Description:
FIELD  
       [0001]     This invention relates generally to the field of a temperature indicating device for use upon a body. More particularly, the invention relates to a disposable, thermally responsive temperature indicating device for use within tissues of a living human body during surgery, particularly open surgery and minimally invasive surgery such as laparoscopic surgery.  
       BACKGROUND  
       [0002]     Disposable instruments for indicating the internal temperature of food products have been known for some time. One example of such a device is commonly referred to as a “pop-up” temperature indicating device, which includes a cylindrical housing and an indicator rod. The indicator rod is held in a retracted position in the housing by a fusible material, with the retracted position biased by a compressed coil spring. Upon achieving a predetermined temperature, the fusible material softens and looses its hold on the indicator rod. Upon release of the indicator rod from the fusible material, the spring decompresses and moves the indicator rod into an extended position out of the housing.  
         [0003]     According to U.S. Pat. No. 5,323,730 entitled “Thermally Responsive Indicator With Organic Retaining Means” to Ou-Yang, the retaining material has typically comprised metal alloys, as in U.S. Pat. Nos. 3,140,611; 3,682,130; 3,693,579 and 3,713,416. The &#39;611 patent, for example, refers to an alloy consisting of bismuth—52%, lead—40%, cadmium—8%, to which is added two parts of Wood&#39;s alloy. The &#39;730 Patent goes on to indicate that, while devices employing such alloy retaining materials have proven useful, they have certain drawbacks. For example, such alloys are typically prepared from toxic metallic substances such as bismuth, lead, cadmium and tin.  
         [0004]     While disposable temperature indicating devices have been used for indicating the internal temperature of food products, such devices have not been considered for use upon tissues of a living human body during surgery.  
         [0005]     Some forms of surgery involve killing tissue to achieve a therapeutic result. The term “ablative surgery” as used herein refers to any of a variety of methods used to kill tissue, with one specific method comprising radio frequency ablation.  
         [0006]     To be successful, ablation treatment may require a certain precision. The surgeon must target a particular region, and be careful not to cause unnecessary trauma to surrounding areas of the patient&#39;s body near the target area. Just as important, the surgeon must be confident that the procedure within the target area has been appropriately performed. For example, the surgeon may need to determine whether the tissue has been ablated.  
         [0007]     What is needed is a disposable temperature indicating device suitable for use upon tissues of a living human body during surgery, particularly during surgery involving ablation.  
       SUMMARY OF THE INVENTION  
       [0008]     According to one embodiment of the present invention, a method of treating tissue of a body during a surgical procedure is provided which comprises: providing tissue comprising normal tissue and abnormal tissue; inserting at least one temperature indicating device into the tissue, with the temperature indicating device comprising an indicator to provide an indication of when a trigger temperature has been attained and a trigger mechanism to trigger an activation of the indicator when heated to the trigger temperature; heating the tissue sufficiently to ablate at least a portion of the abnormal tissue; and transferring heat from the tissue to the trigger mechanism, with the heat sufficient to heat the trigger mechanism to the trigger temperature and trigger the activation of the indicator.  
         [0009]     According to another embodiment of the present invention, a method of treating tissue of a body during a surgical procedure is provided which comprises: providing tissue comprising normal tissue and abnormal tissue; inserting at least one temperature indicating device into the tissue, with the temperature indicating device comprising a pop-up temperature indicating device; heating the tissue sufficiently to ablate at least a portion of the abnormal tissue; and transferring heat from the tissue to the pop-up temperature indicating device, with the heat sufficient to trigger the pop-up temperature indicating device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     To better understand and appreciate the invention, refer to the following detailed description in connection with the accompanying drawings, hand and/or computer generated:  
         [0011]      FIG. 1  is a cross-sectional side view of a temperature indicating device according to the present invention with the treatment indicator in a retracted position;  
         [0012]      FIG. 2  is a top end view of the temperature indicating device of  FIG. 1 ;  
         [0013]      FIG. 3  is a bottom end view of the temperature indicating device of  FIG. 1 ;  
         [0014]      FIG. 4  is a cross-sectional side view of the temperature indicating device of  FIG. 1  with the treatment indicator in an extended position;  
         [0015]      FIG. 5  is a side view of the temperature indicating device of  FIG. 1 ;  
         [0016]      FIG. 6  is a side view of the temperature indicating device of  FIG. 1  inserted into tissue and used with a body imaging device;  
         [0017]      FIG. 7  is a side view of an alternative imaging probe for use with the body imaging device of  FIG. 6 ;  
         [0018]      FIG. 8  is a side view of another embodiment of inserting the temperature indicating device of  FIG. 1  into tissue;  
         [0019]      FIG. 9  is a block diagram of an electrosurgical system used with the temperature indicating device of  FIG. 1 ;  
         [0020]      FIG. 10  is an exploded perspective view of an assembly of an electrosurgical device used with the temperature indicating device of  FIG. 1   
         [0021]      FIG. 11  is a cross-sectional side view of a distal end portion of the electrosurgical device of  FIG. 10  in conjunction with the temperature indicating device of  FIG. 1  in tissue;  
         [0022]      FIG. 12  is a top (plan) view of the tissue after being treated with the electrosurgical device of  FIG. 10 ;  
         [0023]      FIG. 13  is a cross-sectional side view of the tissue of  FIG. 12  taken along section line  13 - 13  of  FIG. 12 ;  
         [0024]      FIG. 14  is a cross-sectional side view of a distal end portion of another embodiment of an electrosurgical device used with the temperature indicating device of  FIG. 1 ; and  
         [0025]      FIG. 15  is a cross-sectional side view of a distal end portion of another embodiment of an electrosurgical device used with the temperature indicating device of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0026]     Throughout the present description, like reference numerals and letters indicate corresponding structure throughout the several views, and such corresponding structure need not be separately discussed. Furthermore, any particular feature(s) of a particular exemplary embodiment may be equally applied to any other exemplary embodiment(s) of this specification as suitable In other words, features between the various exemplary embodiments described herein are interchangeable as suitable, and not exclusive.  
         [0027]     Reference will now be made to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the preferred embodiments of the invention describe exemplary temperature indicating devices and methods of use, it should be understood that their combination is for purposes of illustration only. In other words, it should be understood that the use of the temperature indicating devices of the present invention is not limited to the surgical methods disclosed herein. Conversely, it should be equally understood that the methods of the present invention can potentially be used with a wide variety of temperature indicating devices.  
         [0028]     An exemplary temperature indicating device  10  according to the present invention is shown throughout  FIGS. 1-5 . As shown, device  10  preferably comprises a disposable pop-up temperature indicating device. The pop-up temperature indicating device  10  provides a visual indicator to a surgeon, via a two-position, mechanical mechanism, of when a predetermined internal tissue temperature has been achieved upon tissue treatment, without having to measure tissue temperature itself, or monitor temperature gauges over a time period. Furthermore, the temperature indicating device  10  preferably is configured for both open surgery and minimally invasive surgery, such as laparoscopic surgery. For example, for laparoscopic surgery, preferably device  10  is configured to fit through either a 5 mm or 10 mm trocar cannula, and be inserted into tissue at an internal treatment site with reduced trauma to the tissue and patient as compared to open surgery.  
         [0029]     The temperature indicating device  10  preferably includes an elongated tubular shaped housing  12  having an intermediate barrel portion  14 , a distal (conical) tip portion  16  terminating in a distal pointed tip  18  and a transversely extending ring flange  20  formed opposite the distal pointed tip  18 .  
         [0030]     Device  10  may be inserted into the tissue of a patient by positioning distal pointed tip  18  against the tissue and pushing the tip  18  manually into the tissue. Device  10  will continue to penetrate through the tissue until the underside surface  22  of flange  20  makes contact with the surface of the tissue.  
         [0031]     As shown, preferably the narrowed distal portion  25  of barrel portion  14  includes at least one, and more preferably a plurality (series) of semi-circular tissue engagement protrusions  26  extending at least partially circumferentially around barrel portion  14  and near the distal end of barrel portion  14 . Protrusions  26  may be used to better retain the housing  12  in the tissue and inhibit housing  12  from sliding out of tissue when in use.  
         [0032]     Apart from protrusions  26 , a variety of retention mechanisms may be used with the present invention to help retain the housing  12  in the tissue. However, in order in order to reduce potential trauma to tissue at the time the device  10  is removed from the patient, preferably the housing  12  does not make use of any retention mechanisms which may result in the tearing of tissue with removal of housing  12  therefrom, such as may occur with, for example, reverse, sharp-tip barbs.  
         [0033]     Proximal portion  28  of barrel portion  14  may include at least one planar exterior surface  27 , as shown in  FIGS. 3 and 5 , extending longitudinally thereon. More preferably, the proximal portion  28  of barrel portion  14  forms the shape of a polygon as shown in  FIG. 3  and, even more preferably, the polygon has an even number of sides such as a hexagon, octagon or decagon.  
         [0034]     As shown in  FIG. 5 , planar surface  27  also preferably includes a series of markings  29  which correspond to the distance from pointed tip  18 . In this manner, a length measurement scale is provided which corresponds to the depth of penetration of device  10  into tissue upon insertion. As shown, the length measurement scale comprises numeric reference characters, and is divided into units comprising millimeters with increments from about 6 mm to 40 mm. Other reference characters such as alphanumeric characters may also be used, and other suitable units/increments may comprise, for example, centimeters or inches.  
         [0035]     Once in the tissue, the location of device  10  may be located by a surgeon using body imaging techniques including intraoperative ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI). The planar surface  27  of the proximal portion  28  of barrel portion  14  will generally provide a more detailed ultrasonic image than a curved surface.  
         [0036]     As best shown in  FIG. 4 , the housing  12  is preferably formed with a longitudinally extending blind bore  30  extending from an open end  32  in the middle (center) of ring flange  20  to a closed end  34  near tip  18 . As shown, the open end  32  preferably has a greater cross sectional opening area than the remainder of bore  30  to help facilitate assembly of temperature indicating device  10  as discussed in greater detail below.  
         [0037]     As shown in  FIG. 1 , and looking into the bore  30  of the housing  12 , a localized annular restriction  36  is created in bore  30  by an inward (narrowing) conical tapered portion  38  in barrel portion  14  which initially narrows bore  30  from about the open end  32 , and thereafter an outward (widening) conical tapered portion  40  in barrel portion  14  enlarges bore  30 . As discussed in greater detail below, the tapered portions  38 ,  40  defining annular restriction  36  provide both a lead-in for assembly of a treatment indicator rod  52  to housing  12 , and thereafter a shoulder which inhibits the removal of indicator rod  52  from the housing  12  once the indicator rod  52  has been assembled thereto.  
         [0038]     Spaced inwardly from restriction  36 , the bore  30  is made up of a first interior cylindrical portion  42  which extends to inward (narrowing) conical tapered portion  44 . Conical tapered portion  44  thereafter extends to second interior cylindrical portion  46  which terminates in closed end  34 . In accordance with bore  30 , the interior cavity of housing  12  comprises a first cylindrical cavity  48  and a second cylindrical cavity  50 .  
         [0039]     As shown in  FIG. 1 , the cylindrical portion  46  of housing  12  may include at least one outward (widening) recess  86 , and at least one inward (narrowing) protrusion  88  into cavity  50 . Here, recess  86  comprises a semi-circular recess extending at least partially circumferentially around interior cylindrical portion  46 , while protrusion  88  comprises a semi-circular protrusion extending at least partially circumferentially around interior cylindrical portion  46 .  
         [0040]     As shown in  FIGS. 1 and 4 , an indicator rod  52  is positioned in the bore  30  of housing  12 . In  FIG. 1  the indicator rod  52  is shown in a retracted untriggered (unfired) position relative to the housing  12  while in  FIG. 4  the indictor rod  52  is shown in an extended triggered (fired) position relative to the housing  12 . During use of device  10 , the indictor rod  12  slides between the retracted and extended positions as discussed in greater detail below.  
         [0041]     The indicator rod  52  preferably includes an enlarged cap portion  54  which completely covers the open end  32  of bore  30 . Furthermore, the planar underside surface  56  of the cap portion  54  is preferably configured to mate with the planar upper surface  24  of the flange  20  on the housing  12 . In the above manner, the device  10  is configured to inhibit fluids present during surgery from entering the housing  12 .  
         [0042]     At the upper or proximal end of the indicator rod  52  beneath the enlarged cap portion  54  is located a rod head portion  58  which extends to a collar portion  60 . As shown, the rod head portion  58  preferably has a diameter smaller than the diameter of annular restriction  36  such that rod head portion  58  may slide within annular restriction  36 .  
         [0043]     Preferably the diameter of rod head portion  58  is only slightly smaller than the diameter of annular restriction  36  (about 0.025 mm-0.1 mm) as to inhibit fluids present during surgery from entering the housing  12  between the rod head portion  58  and annular restriction  36 . Furthermore, with this configuration annular restriction  36  is also configured to guide the sliding of rod  52  within bore  30 .  
         [0044]     As shown, collar portion  60  preferably has a diameter smaller than the diameter of cylindrical portion  42  such that collar portion  60  may slide within cylindrical portion  42 , but greater than the diameter of annular restriction  36  to inhibit the removal of indicator rod  52  from the housing  12  once the indicator rod  52  has been assembled thereto. To assembly rod  52  to housing  12 , collar portion  60  may be forced into cavity  48  past annular restriction  36  at a high rate of speed possibly while the housing  12  is simultaneously heated to soften and/or expand.  
         [0045]     Preferably the diameter of collar portion  60  is only slightly smaller than the diameter of cylindrical portion  42  (about 0.025 mm-0.1 mm) as to inhibit fluids present during surgery from entering cavities  48  and  50  of the housing  12  between the collar portion  60  and cylindrical portion  42 . Furthermore, preferably the collar portion  60  is configured to seat against the annular restriction  36  (when the indicator rod  52  is in its extended position) to also inhibit fluids present during surgery from entering cavities  48  and  50  of the housing  12  between the collar portion  60  and annular restriction  36 . To provide a better seal, o-rings may also be used in a manner known in the art.  
         [0046]     Beneath the collar portion  60  is located an indicator rod intermediate portion  62  which extends to a conical tapered portion  66 . As shown, preferably intermediate portion  62  has a diameter smaller than that of collar portion  62  such that a linear coiled spring  68  overlying intermediate portion  62  may seat against and be compressed against the collar shoulder  64 . Furthermore, in this manner, intermediate portion  62  provides a mandrel to support the interior of spring  68 .  
         [0047]     As shown in  FIG. 1 , conical tapered portion  66  is configured to seat against conical tapered portion  44  of housing  12  to inhibit fluids present during surgery from entering cavity  50  of the housing  12  between conical tapered portion  66  of rod  52  and conical tapered portion  44  of housing  12 .  
         [0048]     As shown, conical tapered portion  44  of housing  12  also provides an opposing shoulder portion  70  for seating spring  68  there against. In this manner, spring  68  may now be compressed between the collar shoulder  64  of the indicating rod  52  and slanted shoulder  70  of the housing when the indicator rod  52  is fully inserted in the housing  12 .  
         [0049]     Beneath tapered portion  66  of rod  52 , a rod distal portion  72  comprises cylindrical portion  74  which thereafter extends to conical tapered portion  76  and cylindrical portion  78  with the rod terminating in expanded distal tip portion  80 . As shown, preferably the rod distal portion  72  has a diameter smaller than the diameter of cylindrical portion  46  of housing  12  such that rod distal portion  72  may enter cylindrical cavity  50 .  
         [0050]     Conical tapered portion  76  provides a lead-in for cylindrical portion  74  into cylindrical cavity  50 . Cylindrical portion  74  preferably has a diameter only slightly smaller than the diameter of cylindrical portion  46  to promote the centering of cylindrical portion  78  and expanded distal tip portion  80  within cavity  50 .  
         [0051]     A fusible material  84  at least partially fills cavity  50  around the distal portion  72  of rod  52 . The fusible material  84  is preferably in the form of a solid under normal room temperature conditions, about 22° C. (degrees Celsius), as shown in  FIG. 1 .  
         [0052]     As also shown in  FIG. 1 , cylindrical portion  78  is partially embedded in fusible material  84  and expanded distal tip portion  80  is completely embedded in fusible material  84  to retain the indicator rod  52  in the housing  12 . Increasing or decreasing the amount of fusible material  84  may be used to respectively increase or decrease both the surface area of the cylindrical portion  78  of rod  52  and cylindrical portion  46  of housing  12  engaged by the fusible material  84 , and hence increase or decrease the retention strength of the indicator rod  52  to the housing  12  by fusible material  84 .  
         [0053]     As shown in  FIG. 1 , when fusible material  84  is a solid, a mechanical engagement between the fusible material  84  and rod  52  is created by the fusible material  84  overlying shoulder  82  of expanded distal tip portion  80 . Similarly, mechanical engagement between the fusible material  84  and housing  12  is created by the fusible material  84  within recess  86  and the fusible material  84  underlying protrusion  88 . These various mechanical engagements further increase the retention strength of the indicator rod  52  to the housing  12  by fusible material  84 .  
         [0054]     The fusible structural link between indicator rod  52  and housing  12  provided by material  84  is configured to physically weaken (e.g. by softening and/or melting into a liquid) and deform, and lose its ability to retain indicator rod  52  at its retracted position against the force of spring  68  at a predetermined trigger temperature, thus providing a trigger mechanism for the release of indicator rod  52 . Thereafter, the decompression force associated with compressed spring  68  provides a propulsion mechanism for the travel of indicator rod  52  from its retracted to extended positions.  
         [0055]     Preferably the fusible material has a melting temperature or softening temperate in the range between and including about 45° C. to 80° C. (113° F. to 176° F.), and more preferably in the range between and including about 50° C. to 75° C. (122° F. to 167° F.), and even more preferably in the range between and including about 55° C. to 70° C. (131° F. to 158° F.). As discussed in greater detail below, the fusible material is heated with heat which has transferred to from the tissue to device  10 .  
         [0056]     Fusible material  84  may comprise various materials, including metals, metal alloys, polymers and organic materials. However, preferably fusible material  84  comprises a material biocompatible with the human body. As used herein, a “biocompatible material” refers to a material having the properties of not producing toxic or injurious effects on biological function, and not provoking a significant rejection or immune response. Preferably, the material as used complies with international standard ISO 10993 (International Standards Organization) for biological evaluation of medical devices. An exemplary fusible material comprises wax, and more preferably sterile beeswax.  
         [0057]     An exemplary medical use for the temperature indicating device  10  disclosed herein involves the treatment of at least one mass of abnormal tissue (e.g. tumor, neoplasm, cyst) at least partially surrounded by normal (healthy) tissue. As shown in  FIG. 6 , tissue  100  comprises normal tissue  104 , as well as abnormal tissue  106  and  108 . As shown, abnormal tissue  106  comprises a tumor and, more specifically, a completely “sub-surface” tumor. In other words, a tumor which is located completely beneath the tissue surface  102 . Alternatively, abnormal tissue  108  comprises a “surface” tumor where at least a portion of the tumor is present at the tissue surface  102 .  
         [0058]     As shown in  FIG. 6 , in order to locate the boundaries of abnormal tissue  106  and  108 , a surgeon preferably will first use a body imaging apparatus  110  in a known manner. Body imaging apparatus  110  preferably comprises an ultrasonic body imaging apparatus. However, other body imaging methodologies and apparatus may be used, including computerized tomography (CT), magnetic resonance imaging (MRI) and X-ray.  
         [0059]     As shown, body imaging apparatus  110  makes use of a disc-shaped imaging probe  112  configured for open surgery. However, imaging probe  112  may also be configured for laparoscopic surgery and passage through a trocar cannula, such as the cylindrical imaging probe  114  shown in  FIG. 7 .  
         [0060]     Once the surgeon has located and positioned the abnormal tissue  106 ,  108  through the use of the body imaging apparatus  110 , the surgeon may then insert temperature indicating device  10  into the tissue  100 . As indicated above, temperature indicating device  10  may be inserted into the tissue  100  of a patient by positioning distal pointed tip  18  against the tissue  100  and pushing the tip  18  into the tissue  100 . As shown in  FIG. 6 , temperature indicating device  10  has been inserted into tissue  100  at an angle of about 30-60° (forty-five degrees) normal to the tissue surface  102 .  
         [0061]     Before inserting temperature indicating device  10  into tissue  100 , preferably the surgeon has identified a targeted tissue treatment section  117  with a border  115  which includes a predetermined margin M of normal tissue  104  around abnormal tissue  106 ,  108 . From predetermined margin M of normal tissue  104 , preferably the surgeon will then insert the temperature indicating device  10  into tissue  104  as to position the thermally responsive fusible material portion of temperature indicating device  10  at the border  115  of the predetermined margin M and targeted tissue treatment section  117 . In this manner, the surgeon will be alerted by the triggering of temperature indicating device  10  once the tissue  104  at the border  115  has been treated as desired, and the treatment of tissue  104 ,  106  and  108  within the targeted tissue treatment section  117  should be considered complete.  
         [0062]     As shown in  FIG. 6 , preferably the surgeon will insert temperature indicating device  10  only into normal tissue  104  as to inhibit any spread of abnormal tissue  106 ,  108 . The size of the predetermined margin M depends on numerous factors including whether the abnormal tissue  106 ,  108  is capsulized. If the abnormal tissue  106 ,  108  is capsulized, the predetermined margin may be somewhat small than if the abnormal tissue  106 ,  108  is uncapsulized.  
         [0063]     In certain instances it is recognized that temperature indicating device  10  may have to be partially inserted into abnormal tissue  106 , such as shown in  FIG. 8 , where the mass of abnormal tissue  106  is particularly large. In this situation, it may be desirable to have the thermally responsive fusible material portion of temperature indicating device  10  penetrate through the abnormal tissue  106  and be located in normal tissue  104  to provide predetermined margin M.  
         [0064]     After temperature indicating device  10  has been inserted into normal tissue  104 , the tissue  100  is then preferably treated with a hand held and manipulated surgical device configured to provide energy to the tissue  100  to heat the tissue  100 . An exemplary system  94  having a surgical device  120  is shown in  FIG. 9 . Surgical device  120  preferably comprises an electrosurgical device and more preferably comprises a bipolar, radio frequency, electrosurgical device. Even more preferably, surgical device  120  comprises a fluid-assisted, bipolar, radio frequency, electrosurgical device. Such devices assigned to the assignee of the present invention are disclosed in PCT International Publication Nos. WO 03/024349 A1 and WO 03/082134 A1, both entitled “Fluid-Assisted Medical Devices, Systems and Methods” and hereby incorporated by reference in their entirety.  
         [0065]     As shown in  FIG. 9 , electrosurgical device  120  is preferably part of a system  94  comprising a fluid source  90  and an electrical energy source  92 . Electrosurgical device  120  is preferably coupled to energy source  92  via insulated wire conductors  96   a,    96   b.  With respect to the fluid coupling, fluid  116  from the fluid source  90  is preferably communicated from fluid source  90  to electrosurgical device  120  through a flexible, polyvinylchloride (PVC) fluid line  98  having a lumen  99 .  
         [0066]     Energy source  92  preferably comprises a generator, and more preferably a radio frequency alternating current generator which may provide radio frequency power therefrom at selected increments. Fluid source  90  preferably comprises an intravenous bag containing electrically conductive fluid, which more preferably comprises saline. More preferably, the saline comprises sterile, and even more preferably, normal saline. Although the description herein will specifically describe the use of saline as the fluid, other electrically conductive fluids, as well as non-conductive fluids, can be used in accordance with the invention.  
         [0067]     For example, in addition to the conductive fluid comprising physiologic saline (also known as “normal” saline, isotonic saline or 0.9% sodium chloride (NaCl) solution), the conductive fluid may comprise hypertonic saline solution, hypotonic saline solution, Ringers solution (a physiologic solution of distilled water containing specified amounts of sodium chloride, calcium chloride, and potassium chloride), lactated Ringer&#39;s solution (a crystalloid electrolyte sterile solution of distilled water containing specified amounts of calcium chloride, potassium chloride, sodium chloride, and sodium lactate), Locke-Ringer&#39;s solution (a buffered isotonic solution of distilled water containing specified amounts of sodium chloride, potassium chloride, calcium chloride, sodium bicarbonate, magnesium chloride, and dextrose), or any other electrolyte solution. In other words, a solution that conducts electricity via an electrolyte, a substance (salt, acid or base) that dissociates into electrically charged ions when dissolved in a solvent, such as water, resulting solution comprising an ionic conductor.  
         [0068]     An exemplary electrosurgical device  120  configured to provide radio frequency power and fluid simultaneously during the treatment of tissue  100 , and which may be used in conjunction with the system and methods of the present invention, is shown in  FIGS. 10 and 11 . As shown electrosurgical device  120  comprises a bipolar electrosurigcal device. With a bipolar device, in the presence of alternating current, an electrical circuit is created with the electrodes of the device, which alternate in polarity between positive and negative charges with the current flow from the positive to the negative charge.  
         [0069]     As shown in  FIG. 10 , bipolar electrosurgical device  120  preferably includes two arms comprising rigid, self-supporting, hollow shafts  122   a,    122   b,  a proximal handle comprising mating handle portions  124   a,    124   b  and arm tip portions as shown by circles  126   a,    126   b.  In this embodiment, shafts  122   a,    122   b  preferably comprise thick walled metal hypo-tubing. In this manner, the shafts  122   a,    122   b  have sufficient rigidity to maintain their form during use of device  120  without kinking or significant bending. The handle is configured for hand holding of device  120 , and for hand manipulation of tip portions  126   a,    126   b  of device  120 . It is preferably made of a sterilizable, rigid, non-conductive material, such as a polymer (e.g., polycarbonate).  
         [0070]     As shown in  FIGS. 9 , fluid  116  for device  120  is first communicated down lumen  99  of fluid line  98 . As shown in  FIGS. 10 and 11 , fluid  116  then flows from lumen  99  of fluid line  98  to lumens  99   a,    99   b  of fluid lines  98   a,    98   b.  Fluid lines  98   a,    98   b  are preferably interference fit over the outside diameter of shafts  122   a,    122   b  to provide a press fit seal there between. As shown in  FIG. 11 , fluid  116  then flows within the lumens  128   a,    128   b  of shafts  122   a,    122   b  and through the lumens  130   a,    130   b  and cavities  132   a,    132   b  of metal sleeves  134   a,    134   b  disposed at the end of shafts  122   a,    122   b  where it is expelled from outlet openings  136   a,    136   b  around the electrodes  138   a,    138   b,  which comprise solid metal balls. Electrodes  138   a,    138   b  are retained within sleeves  134   a,    134   b  by crimps located at the distal end of the sleeves  138   a,    138   b.    
         [0071]     Radio frequency energy for electrodes  138   a,    138   b  is provided from electrical energy source  92  through insulated wire conductors  96   a,    96   b  which are electrically coupled (e.g. welded) to shafts  122   a,    122   b  and connectable to energy source  92  via two banana (male) plug connectors  97   a,    97   b.  Electric current from energy source  92  thereafter flows from shafts  122   a,    122   b  to metal sleeves  134   a,    134   b,  springs  140   a,    140   b  and finally to electrodes  138   a,    138   b  which are all in physical contact. Electrical insulators  142   a,    142   b,  preferably comprising shrink wrap polymer tubing, surround shafts  122   a,    122   b  and sleeves  134   a,    134   b  along substantially their entire exposed length.  
         [0072]     As best shown in  FIG. 11 , when device  120  is in use electrodes  138   a,    138   b  are laterally spaced adjacent tissue surface  102  of tissue  100 . As shown, the electrodes  138   a,    138   b  are fluidly coupled to the surface  102  of tissue  100  by fluid couplings  118   a,    118   b  which preferably comprise discrete, localized webs and more specifically comprise triangular shaped web portions which provide a film of fluid  116  between surface  102  of tissue  100  and electrodes  138   a,    138   b.  When the user of electrosurgical device  120  places electrodes  138   a,    138   b  at a tissue treatment site and moves electrodes  138   a,    138   b  across surface  102  of tissue  100 , fluid  116  is expelled around and on the surfaces of electrodes  138   a,    138   b  at the distal ends of sleeves  134   a,    134   b  and onto surface  102  of tissue  100  via couplings  118   a,    118   b.  At the same time, radio frequency electrical energy (current), shown by electrical field lines  144 , is provided to tissue  100  at tissue surface  102  and below tissue surface  102  into tissue  100  through fluid couplings  118   a,    118   b.    
         [0073]     In addition to fluid  116  providing an electrical coupling between the electrosurgical device  120  and tissue  100 , fluid  116  lubricates surface  102  of tissue  100  and facilitates the movement of electrodes  138   a,    138   b  across surface  102  of tissue  100 . During movement of electrodes  138   a,    138   b,  electrodes  138   a,    138   b  typically slide across the surface  102  of tissue  100 , but also may rotate as electrodes  138   a,    138   b  move across surface  102  of the tissue  100 . Typically the user of electrosurgical device  120  slides electrodes  138   a,    138   b  across surface  102  of tissue  100  back and forth with a painting motion, preferably in an outwardly spirally circular pattern over the abnormal tissue  106 ,  108  while using fluid  116  as, among other things, a lubricating coating. Preferably the thickness of the fluid  116  between the distal end surface of electrodes  138   a,    138   b  and surface  102  of tissue  100  at the outer edge of couplings  118   a,    118   b  is in the range between and including about 0.05 mm to 1.5 mm. More preferably, fluid  116  between the distal end surface of electrodes  138   a,    138   b  and surface  102  of tissue  100  at the outer edge of coupling  118   a,    118   b  is in the range between and including about 0.1 mm to 0.3 mm. In certain embodiments, the distal end tip of electrodes  138   a,    138   b  may contact surface  102  of tissue  100  without any fluid  116  in between.  
         [0074]     With use of electrosurgical device  120 , the heating of the tissue  100  is generated due to the electrical resistance of the tissue  100 . In other words, increasing the temperature of the tissue  100  as a result of electric current flow through the tissue  100 , with the electrical energy being absorbed from the voltage and transformed into thermal energy (i.e. heat) via accelerated movement of ions as a function of the tissue&#39;s electrical resistance. In addition to the heating of tissue  100 , thermal heat generated in tissue  100  is transferred to device  10  and thereafter to fusible material  84 .  
         [0075]     Deleterious effects in the cells making up the tissue  100  begin to occur at about 42° C. As the temperature of the tissue  100  increases due to heat generated by the tissue&#39;s resistance, the tissue  100  will undergo profound changes and eventually, as the temperature becomes high enough, that is, generally greater than 45° C., the cells will die. As the temperature increases beyond cell death temperature, complete disintegration of the cell walls and cells may be caused by boiling of the tissue&#39;s (intracellular and intercellular) water. Cell death temperatures can vary with the type of tissue to which the power is being applied, but generally will begin to occur within the range of about 45° C. to 60° C., though actual cell death of certain tissue cells may occur at a higher temperature.  
         [0076]      FIGS. 12 and 13  show tissue  100  after it has been treated with use of electrostirgical device  120 .  FIG. 12  shows a top view of the tissue  100 , which also shows a plurality of temperature indicating devices  10  arranged so as to surround abnormal tissue  106 ,  108 .  
         [0077]      FIG. 13  shows a cross-section of the tissue treated with use of electrosurgical device  120  taken along line  13 - 13  of  FIG. 12 . More specifically,  FIG. 12  shows a cross-sectional side view of a semi-spherical treated tissue section  148  which is defined by border  158 . Treatment section  148  may be sub-divided into an ablation zone  150  and a hemorrhagic zone  152 . In addition to border  158  defining the tissue treatment section  148 , border  158  also defines the outer border of hemorrhagic zone  152 . The transition between ablation zone  150  and a hemorrhagic zone  152  is defined by border  156 .  
         [0078]     Ablation zone  150  comprises tissue which has been thermally heated during the surgical procedure sufficiently to kill the cells thereof, while hemorrhagic zone  152  comprises tissue which has been thermally heated during the surgical procedure, but not sufficiently to kill the cells thereof. Native zone  154  comprises tissue unaltered by the surgical procedure.  
         [0079]     As shown in  FIGS. 12 and 13 , it is important that the ablation zone  150  at least encompass the detected abnormal tissue  106  and  108 . Furthermore, as shown in  FIG. 12 , preferably ablation zone  150  typically includes at least a portion, and more preferably all, of the predetermined margin M of normal tissue  104  around the abnormal tissue  106 ,  108  to better ensure that all the abnormal tissue  106 ,  108  is within ablation zone  140 .  
         [0080]     While obtaining a predetermined margin M of normal tissue  104  ablation may be preferred, minimizing the amount of normal tissue  104  ablation outside the margin M is also desirable. By positioning the thermally responsive fusible material portion of temperature indicating device  10  at the border  115  of the predetermined margin M and targeted tissue treatment section  117  (as shown in  FIG. 6 ), the surgeon is assured that the ablation zone  150  substantially coincides with the targeted tissue treatment section  117 . In this manner, no more normal tissue  104  is ablated than desired.  
         [0081]     While the use of a margin M has been described with respect to the use of one of the temperature indicating devices  10  shown in  FIG. 12 , it should be understood that all the temperature indicating devices  10  shown in  FIG. 12  preferably make use of a margin M. It should also be understood that the exact shape of the treated tissue section  148  depends on the shape of the abnormal tissue  106 ,  108  and that a spherical treated tissue section  148  as described herein is merely exemplary.  
         [0082]     In other embodiments, as shown in  FIG. 14 , electrosurgical device  120  may comprises a bipolar device having electrodes  138   a,    138   b  comprising two needles with each having at least one fluid outlet opening  136   a,    136   b  through which fluid  116  and radio frequency energy may be delivered into tissue  100 . Zones  160   a,    160   b  of tissue  100  comprise tissue  100  which has been infiltrated by fluid  116 .  
         [0083]     In still other embodiments, as shown in  FIG. 15 , electrosurgical device  120  may comprise a monopolar device. More specifically, as shown in  FIG. 15 , electrosurgical device comprises a single electrode  138  comprising a needle having at least one fluid outlet opening  136  through which fluid  116  and radio frequency energy may be delivered into tissue  100 . As shown, electrode  138  has been inserted into and through abnormal tissue  106 , and fluid  116  has completely infiltrated abnormal tissue as shown by fluid infiltration zone  160  which is defined by fluid infiltration border  162 .  
         [0084]     With use of a monopolar device  120 , the first electrode, often referred to as the active electrode, comprises electrode  138  of the electrosurgical device  120  while a second electrode, often referred to as the indifferent or return electrode, comprises a ground pad dispersive electrode  164  located on the patient and coupled to energy source  92 , typically on the back or other suitable anatomical location. An electrical circuit is formed between electrode  138  and ground pad dispersive electrode  164  with electrical current flowing from electrode  138  through the patient to ground pad dispersive electrode  164  in a manner known in the art.  
         [0085]     In addition to the monopolar device shown in  FIG. 15 , it should be understood that the bipolar device shown in  FIGS. 10 and 11  can be also used as a monopolar device with the elimination of one of the electrodes thereof.  
         [0086]     From the specification, it should be clear that any use of the terms “distal” and “proximal” are made in reference from the user of the device  10 , and not the patient. Furthermore, it should also be understood that such terms are used to distinguish the various portions of device  10  relative to one another, and as device  10  will preferably be used as shown in the figures. Consequently, these terms should not be understood to be otherwise limiting since device  10  may obviously be disposed in many different orientations when in actual use.  
         [0087]     While a preferred embodiment of the present invention has been described, it should be understood that various changes, adaptations and modifications can be made therein without departing from the spirit of the invention and the scope of the appended claims. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.  
         [0088]     Furthermore, it should be understood that the appended claims do not necessarily comprise the broadest scope of the invention which the Applicant is entitled to claim, or the only manner(s) in which the invention may be claimed, or that all recited features are necessary.  
         [0089]     All publications and patent documents cited in this application are incorporated by reference in their entirety for all purposes, to the extent they are consistent.