Temperature indicating devices and methods of use

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.

FIELD

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

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.

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 '611 patent, for example, refers to an alloy consisting of bismuth-52%, lead-40%, cadmium-8%, to which is added two parts of Wood's alloy. The '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.

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.

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.

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'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.

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

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.

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.

DETAILED DESCRIPTION

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.

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.

An exemplary temperature indicating device10according to the present invention is shown throughoutFIGS. 1-5. As shown, device10preferably comprises a disposable pop-up temperature indicating device. The pop-up temperature indicating device10provides 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 device10preferably is configured for both open surgery and minimally invasive surgery, such as laparoscopic surgery. For example, for laparoscopic surgery, preferably device10is 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.

The temperature indicating device10preferably includes an elongated tubular shaped housing12having an intermediate barrel portion14, a distal (conical) tip portion16terminating in a distal pointed tip18and a transversely extending ring flange20formed opposite the distal pointed tip18.

Device10may be inserted into the tissue of a patient by positioning distal pointed tip18against the tissue and pushing the tip18manually into the tissue. Device10will continue to penetrate through the tissue until the underside surface22of flange20makes contact with the surface of the tissue.

As shown, preferably the narrowed distal portion25of barrel portion14includes at least one, and more preferably a plurality (series) of semi-circular tissue engagement protrusions26extending at least partially circumferentially around barrel portion14and near the distal end of barrel portion14. Protrusions26may be used to better retain the housing12in the tissue and inhibit housing12from sliding out of tissue when in use.

Apart from protrusions26, a variety of retention mechanisms may be used with the present invention to help retain the housing12in the tissue. However, in order to reduce potential trauma to tissue at the time the device10is removed from the patient, preferably the housing12does not make use of any retention mechanisms which may result in the tearing of tissue with removal of housing12therefrom, such as may occur with, for example, reverse, sharp-tip barbs.

Proximal portion28of barrel portion14may include at least one planar exterior surface27, as shown inFIGS. 3 and 5, extending longitudinally thereon. More preferably, the proximal portion28of barrel portion14forms the shape of a polygon as shown inFIG. 3and, even more preferably, the polygon has an even number of sides such as a hexagon, octagon or decagon.

As shown inFIG. 5, planar surface27also preferably includes a series of markings29which correspond to the distance from pointed tip18. In this manner, a length measurement scale is provided which corresponds to the depth of penetration of device10into 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.

Once in the tissue, the location of device10may be located by a surgeon using body imaging techniques including intraoperative ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI). The planar surface27of the proximal portion28of barrel portion14will generally provide a more detailed ultrasonic image than a curved surface.

As best shown inFIG. 4, the housing12is preferably formed with a longitudinally extending blind bore30extending from an open end32in the middle (center) of ring flange20to a closed end34near tip18. As shown, the open end32preferably has a greater cross sectional opening area than the remainder of bore30to help facilitate assembly of temperature indicating device10as discussed in greater detail below.

As shown inFIG. 1, and looking into the bore30of the housing12, a localized annular restriction36is created in bore30by an inward (narrowing) conical tapered portion38in barrel portion14which initially narrows bore30from about the open end32, and thereafter an outward (widening) conical tapered portion40in barrel portion14enlarges bore30. As discussed in greater detail below, the tapered portions38,40defining annular restriction36provide both a lead-in for assembly of a treatment indicator rod52to housing12, and thereafter a shoulder which inhibits the removal of indicator rod52from the housing12once the indicator rod52has been assembled thereto.

Spaced inwardly from restriction36, the bore30is made up of a first interior cylindrical portion42which extends to inward (narrowing) conical tapered portion44. Conical tapered portion44thereafter extends to second interior cylindrical portion46which terminates in closed end34. In accordance with bore30, the interior cavity of housing12comprises a first cylindrical cavity48and a second cylindrical cavity50.

As shown inFIG. 1, the cylindrical portion46of housing12may include at least one outward (widening) recess86, and at least one inward (narrowing) protrusion88into cavity50. Here, recess86comprises a semi-circular recess extending at least partially circumferentially around interior cylindrical portion46, while protrusion88comprises a semi-circular protrusion extending at least partially circumferentially around interior cylindrical portion46.

As shown inFIGS. 1 and 4, an indicator rod52is positioned in the bore30of housing12. InFIG. 1the indicator rod52is shown in a retracted untriggered (unfired) position relative to the housing12while inFIG. 4the indictor rod52is shown in an extended triggered (fired) position relative to the housing12. During use of device10, the indictor rod52slides between the retracted and extended positions as discussed in greater detail below.

The indicator rod52preferably includes an enlarged cap portion54which completely covers the open end32of bore30. Furthermore, the planar underside surface56of the cap portion54is preferably configured to mate with the planar upper surface24of the flange20on the housing12. In the above manner, the device10is configured to inhibit fluids present during surgery from entering the housing12.

At the upper or proximal end of the indicator rod52beneath the enlarged cap portion54is located a rod head portion58which extends to a collar portion60. As shown, the rod head portion58preferably has a diameter smaller than the diameter of annular restriction36such that rod head portion58may slide within annular restriction36.

Preferably the diameter of rod head portion58is only slightly smaller than the diameter of annular restriction36(about 0.025 mm-0.1 mm) as to inhibit fluids present during surgery from entering the housing12between the rod head portion58and annular restriction36. Furthermore, with this configuration annular restriction36is also configured to guide the sliding of rod52within bore30.

As shown, collar portion60preferably has a diameter smaller than the diameter of cylindrical portion42such that collar portion60may slide within cylindrical portion42, but greater than the diameter of annular restriction36to inhibit the removal of indicator rod52from the housing12once the indicator rod52has been assembled thereto. To assemble rod52to housing12, collar portion60may be forced into cavity48past annular restriction36at a high rate of speed possibly while the housing12is simultaneously heated to soften and/or expand.

Preferably the diameter of collar portion60is only slightly smaller than the diameter of cylindrical portion42(about 0.025 mm-0.1 mm) as to inhibit fluids present during surgery from entering cavities48and50of the housing12between the collar portion60and cylindrical portion42. Furthermore, preferably the collar portion60is configured to seat against the annular restriction36(when the indicator rod52is in its extended position) to also inhibit fluids present during surgery from entering cavities48and50of the housing12between the collar portion60and annular restriction36. To provide a better seal, o-rings may also be used in a manner known in the art.

Beneath the collar portion60is located an indicator rod intermediate portion62which extends to a conical tapered portion66. As shown, preferably intermediate portion62has a diameter smaller than that of collar portion62such that a linear coiled spring68overlying intermediate portion62may seat against and be compressed against the collar shoulder64. Furthermore, in this manner, intermediate portion62provides a mandrel to support the interior of spring68.

As shown inFIG. 1, conical tapered portion66is configured to seat against conical tapered portion44of housing12to inhibit fluids present during surgery from entering cavity50of the housing12between conical tapered portion66of rod52and conical tapered portion44of housing12.

As shown, conical tapered portion44of housing12also provides an opposing shoulder portion70for seating spring68there against. In this manner, spring68may now be compressed between the collar shoulder64of the indicating rod52and slanted shoulder70of the housing when the indicator rod52is fully inserted in the housing12.

Beneath tapered portion66of rod52, a rod distal portion72comprises cylindrical portion74which thereafter extends to conical tapered portion76and cylindrical portion78with the rod terminating in expanded distal tip portion80. As shown, preferably the rod distal portion72has a diameter smaller than the diameter of cylindrical portion46of housing12such that rod distal portion72may enter cylindrical cavity50.

Conical tapered portion76provides a lead-in for cylindrical portion74into cylindrical cavity50. Cylindrical portion74preferably has a diameter only slightly smaller than the diameter of cylindrical portion46to promote the centering of cylindrical portion78and expanded distal tip portion80within cavity50.

A fusible material84at least partially fills cavity50around the distal portion72of rod52. The fusible material84is preferably in the form of a solid under normal room temperature conditions, about 22° C. (degrees Celsius), as shown inFIG. 1.

As also shown inFIG. 1, cylindrical portion78is partially embedded in fusible material84and expanded distal tip portion80is completely embedded in fusible material84to retain the indicator rod52in the housing12. Increasing or decreasing the amount of fusible material84may be used to respectively increase or decrease both the surface area of the cylindrical portion78of rod52and cylindrical portion46of housing12engaged by the fusible material84, and hence increase or decrease the retention strength of the indicator rod52to the housing12by fusible material84.

As shown inFIG. 1, when fusible material84is a solid, a mechanical engagement between the fusible material84and rod52is created by the fusible material84overlying shoulder82of expanded distal tip portion80. Similarly, mechanical engagement between the fusible material84and housing12is created by the fusible material84within recess86and the fusible material84underlying protrusion88. These various mechanical engagements further increase the retention strength of the indicator rod52to the housing12by fusible material84.

The fusible structural link between indicator rod52and housing12provided by material84is configured to physically weaken (e.g. by softening and/or melting into a liquid) and deform, and lose its ability to retain indicator rod52at its retracted position against the force of spring68at a predetermined trigger temperature, thus providing a trigger mechanism for the release of indicator rod52. Thereafter, the decompression force associated with compressed spring68provides a propulsion mechanism for the travel of indicator rod52from its retracted to extended positions.

Preferably the fusible material84has 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 from the tissue to device10.

Fusible material84may comprise various materials, including metals, metal alloys, polymers and organic materials. However, preferably fusible material84comprises 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.

An exemplary medical use for the temperature indicating device10disclosed 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 inFIG. 6, tissue100comprises normal tissue104, as well as abnormal tissue106and108. As shown, abnormal tissue106comprises a tumor and, more specifically, a completely “sub-surface” tumor. In other words, a tumor which is located completely beneath the tissue surface102. Alternatively, abnormal tissue108comprises a “surface” tumor where at least a portion of the tumor is present at the tissue surface102.

As shown inFIG. 6, in order to locate the boundaries of abnormal tissue106and108, a surgeon preferably will first use a body imaging apparatus110in a known manner. Body imaging apparatus110preferably 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.

As shown, body imaging apparatus110makes use of a disc-shaped imaging probe112configured for open surgery. However, imaging probe112may also be configured for laparoscopic surgery and passage through a trocar cannula, such as the cylindrical imaging probe114shown inFIG. 7.

Once the surgeon has located and positioned the abnormal tissue106,108through the use of the body imaging apparatus110, the surgeon may then insert temperature indicating device10into the tissue100. As indicated above, temperature indicating device10may be inserted into the tissue100of a patient by positioning distal pointed tip18against the tissue100and pushing the tip18into the tissue100. As shown inFIG. 6, temperature indicating device10has been inserted into tissue100at an angle of about 30-60° (e.g.,forty-five degrees) normal to the tissue surface102.

Before inserting temperature indicating device10into tissue100, preferably the surgeon has identified a targeted tissue treatment section117with a border115which includes a predetermined margin M of normal tissue104around abnormal tissue106,108. From predetermined margin M of normal tissue104, preferably the surgeon will then insert the temperature indicating device10into tissue104as to position the thermally responsive fusible material portion of temperature indicating device10at the border115of the predetermined margin M and targeted tissue treatment section117. In this manner, the surgeon will be alerted by the triggering of temperature indicating device10once the tissue104at the border115has been treated as desired, and the treatment of tissue104,106and108within the targeted tissue treatment section117should be considered complete.

As shown inFIG. 6, preferably the surgeon will insert temperature indicating device10only into normal tissue104as to inhibit any spread of abnormal tissue106,108. The size of the predetermined margin M depends on numerous factors including whether the abnormal tissue106,108is capsulized. If the abnormal tissue106,108is capsulized, the predetermined margin may be somewhat smaller than if the abnormal tissue106,108is uncapsulized.

In certain instances it is recognized that temperature indicating device10may have to be partially inserted into abnormal tissue106, such as shown inFIG. 8, where the mass of abnormal tissue106is particularly large. In this situation, it may be desirable to have the thermally responsive fusible material portion of temperature indicating device10penetrate through the abnormal tissue106and be located in normal tissue104to provide predetermined margin M.

After temperature indicating device10has been inserted into normal tissue104, the tissue100is then preferably treated with a hand held and manipulated surgical device configured to provide energy to the tissue100to heat the tissue100. An exemplary system94having a surgical device120is shown inFIG. 9. Surgical device120preferably comprises an electrosurgical device and more preferably comprises a bipolar, radio frequency, electrosurgical device. Even more preferably, surgical device120comprises 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.

As shown inFIG. 9, electrosurgical device120is preferably part of a system94comprising a fluid source90and an electrical energy source92. Electrosurgical device120is preferably coupled to energy source92via insulated wire conductors96a,96b. With respect to the fluid coupling, fluid116from the fluid source90is preferably communicated from fluid source90to electrosurgical device120through a flexible, polyvinylchloride (PVC) fluid line98having a lumen99.

Energy source92preferably comprises a generator, and more preferably a radio frequency alternating current generator which may provide radio frequency power therefrom at selected increments. Fluid source90preferably 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.

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'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'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.

An exemplary electrosurgical device120configured to provide radio frequency power and fluid simultaneously during the treatment of tissue100, and which may be used in conjunction with the system and methods of the present invention, is shown inFIGS. 10 and 11. As shown electrosurgical device120comprises 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.

As shown inFIG. 10, bipolar electrosurgical device120preferably includes two arms comprising rigid, self-supporting, hollow shafts122a,122b, a proximal handle comprising mating handle portions124a,124band arm tip portions as shown by circles126a,126b. In this embodiment, shafts122a,122bpreferably comprise thick walled metal hypo-tubing. In this manner, the shafts122a,122bhave sufficient rigidity to maintain their form during use of device120without kinking or significant bending. The handle is configured for hand holding of device120, and for hand manipulation of tip portions126a,126bof device120. It is preferably made of a sterilizable, rigid, non-conductive material, such as a polymer (e.g., polycarbonate).

As shown inFIGS. 9, fluid116for device120is first communicated down lumen99of fluid line98. As shown inFIGS. 10 and 11, fluid116then flows from lumen99of fluid line98to lumens99a,99bof fluid lines98a,98b. Fluid lines98a,98bare preferably interference fit over the outside diameter of shafts122a,122bto provide a press fit seal there between. As shown inFIG. 11, fluid116then flows within the lumens128a,128bof shafts122a,122band through the lumens130a,130band cavities132a,132bof metal sleeves134a,134bdisposed at the end of shafts122a,122bwhere it is expelled from outlet openings136a,136baround the electrodes138a,138b, which comprise solid metal balls. Electrodes138a,138bare retained within sleeves134a,134bby crimps located at the distal end of the sleeves138a,138b.

Radio frequency energy for electrodes138a,138bis provided from electrical energy source92through insulated wire conductors96a,96bwhich are electrically coupled (e.g. welded) to shafts122a,122band connectable to energy source92via two banana (male) plug connectors97a,97b. Electric current from energy source92thereafter flows from shafts122a,122bto metal sleeves134a,134b, springs140a,140band finally to electrodes138a,138bwhich are all in physical contact. Electrical insulators142a,142b, preferably comprising shrink wrap polymer tubing, surround shafts122a,122band sleeves134a,134balong substantially their entire exposed length.

As best shown inFIG. 11, when device120is in use electrodes138a,138bare laterally spaced adjacent tissue surface102of tissue100. As shown, the electrodes138a,138bare fluidly coupled to the surface102of tissue100by fluid couplings118a,118bwhich preferably comprise discrete, localized webs and more specifically comprise triangular shaped web portions which provide a film of fluid116between surface102of tissue100and electrodes138a,138b. When the user of electrosurgical device120places electrodes138a,138bat a tissue treatment site and moves electrodes138a,138bacross surface102of tissue100, fluid116is expelled around and on the surfaces of electrodes138a,138bat the distal ends of sleeves134a,134band onto surface102of tissue100via couplings118a,118b. At the same time, radio frequency electrical energy (current), shown by electrical field lines144, is provided to tissue100at tissue surface102and below tissue surface102into tissue100through fluid couplings118a,118b.

In addition to fluid116providing an electrical coupling between the electrosurgical device120and tissue100, fluid116lubricates surface102of tissue100and facilitates the movement of electrodes138a,138bacross surface102of tissue100. During movement of electrodes138a,138b, electrodes138a,138btypically slide across the surface102of tissue100, but also may rotate as electrodes138a,138bmove across surface102of the tissue100. Typically the user of electrosurgical device120slides electrodes138a,138bacross surface102of tissue100back and forth with a painting motion, preferably in an outwardly spirally circular pattern over the abnormal tissue106,108while using fluid116as, among other things, a lubricating coating. Preferably the thickness of the fluid116between the distal end surface of electrodes138a,138band surface102of tissue100at the outer edge of couplings118a,118bis in the range between and including about 0.05 mm to 1.5 mm. More preferably, fluid116between the distal end surface of electrodes138a,138band surface102of tissue100at the outer edge of coupling118a,118bis in the range between and including about 0.1 mm to 0.3 mm. In certain embodiments, the distal end tip of electrodes138a,138bmay contact surface102of tissue100without any fluid116in between.

With use of electrosurgical device120, the heating of the tissue100is generated due to the electrical resistance of the tissue100. In other words, increasing the temperature of the tissue100as a result of electric current flow through the tissue100, 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's electrical resistance. In addition to the heating of tissue100, thermal heat generated in tissue100is transferred to device10and thereafter to fusible material84.

Deleterious effects in the cells making up the tissue100begin to occur at about 42° C. As the temperature of the tissue100increases due to heat generated by the tissue's resistance, the tissue100will 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'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.

FIGS. 12 and 13show tissue100after it has been treated with use of electrostirgical device120.FIG. 12shows a top view of the tissue100, which also shows a plurality of temperature indicating devices10arranged so as to surround abnormal tissue106,108.

FIG. 13shows a cross-section of the tissue treated with use of electrosurgical device120taken along line13-13ofFIG. 12. More specifically,FIG. 13shows a cross-sectional side view of a semi-spherical treated tissue section148which is defined by border158. Treatment section148may be sub-divided into an ablation zone150and a hemorrhagic zone152. In addition to border158defining the tissue treatment section148, border158also defines the outer border of hemorrhagic zone152. The transition between ablation zone150and a hemorrhagic zone152is defined by border156.

Ablation zone150comprises tissue which has been thermally heated during the surgical procedure sufficiently to kill the cells thereof, while hemorrhagic zone152comprises tissue which has been thermally heated during the surgical procedure, but not sufficiently to kill the cells thereof. Native zone154comprises tissue unaltered by the surgical procedure.

As shown inFIGS. 12 and 13, it is important that the ablation zone150at least encompass the detected abnormal tissue106and108. Furthermore, as shown inFIG. 13, preferably ablation zone150typically includes at least a portion, and more preferably all, of the predetermined margin M of normal tissue104around the abnormal tissue106,108to better ensure that all the abnormal tissue106,108is within ablation zone150.

While obtaining a predetermined margin M of normal tissue104ablation may be preferred, minimizing the amount of normal tissue104ablation outside the margin M is also desirable. By positioning the thermally responsive fusible material portion of temperature indicating device10at the border115of the predetermined margin M and targeted tissue treatment section117(as shown inFIG. 6), the surgeon is assured that the ablation zone150substantially coincides with the targeted tissue treatment section117. In this manner, no more normal tissue104is ablated than desired.

While the use of a margin M has been described with respect to the use of one of the temperature indicating devices10shown inFIG. 12, it should be understood that all the temperature indicating devices10shown inFIG. 12preferably make use of a margin M. It should also be understood that the exact shape of the treated tissue section148depends on the shape of the abnormal tissue106,108and that a spherical treated tissue section148as described herein is merely exemplary.

In other embodiments, as shown inFIG. 14, electrosurgical device120may comprises a bipolar device having electrodes138a,138bcomprising two needles with each having at least one fluid outlet opening136a,136bthrough which fluid116and radio frequency energy may be delivered into tissue100. Zones160a,160bof tissue100comprise tissue100which has been infiltrated by fluid116.

In still other embodiments, as shown inFIG. 15, electrosurgical device120may comprise a monopolar device. More specifically, as shown inFIG. 15, electrosurgical device comprises a single electrode138comprising a needle having at least one fluid outlet opening136through which fluid116and radio frequency energy may be delivered into tissue100. As shown, electrode138has been inserted into and through abnormal tissue106, and fluid116has completely infiltrated abnormal tissue as shown by fluid infiltration zone160which is defined by fluid infiltration border162.

With use of a monopolar device120, the first electrode, often referred to as the active electrode, comprises electrode138of the electrosurgical device120while a second electrode, often referred to as the indifferent or return electrode, comprises a ground pad dispersive electrode164located on the patient and coupled to energy source92, typically on the back or other suitable anatomical location. An electrical circuit is formed between electrode138and ground pad dispersive electrode164with electrical current flowing from electrode138through the patient to ground pad dispersive electrode164in a manner known in the art.

In addition to the monopolar device shown inFIG. 15, it should be understood that the bipolar device shown inFIGS. 10 and 11can be also used as a monopolar device with the elimination of one of the electrodes thereof.

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 device10, and not the patient. Furthermore, it should also be understood that such terms are used to distinguish the various portions of device10relative to one another, and as device10will preferably be used as shown in the figures. Consequently, these terms should not be understood to be otherwise limiting since device10may obviously be disposed in many different orientations when in actual use.

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.

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.

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.