Electrosurgical laryngeal wand

Abstract

A bipolar electrosurgical wand for treating tissue along a patient airway. The wand includes a tubular end effector with an electrically insulative spacer, a return electrode, and an active electrode at its distal end. The active electrode defines a planar top surface, which includes a proximal portion and a tip projection extending directly distally therefrom. The tip projection may include bilateral linear side surfaces, symmetrical about a longitudinal axis of the active electrode. The wand may also include a fluid delivery aperture and a fluid delivery cavity ramp, to direct fluid towards the active electrode for a range of wand orientations.

Description

[0001]PT-6149-WO-PCT Electrosurgical Laryngeal Wand FIELD This application relates generally to methods and apparatus for accessing and treating tissue. More specifically disclosed, is an apparatus and associated method for electrosurgically treating a range of pathological conditions that affect the laryngeal and / or airway anatomy. BACKGROUND Access and treatment of areas along a patient airway, around the larynx presents a unique set of challenges. For example, the airway is narrow, limiting device size. The airway is relative long, requiring a substantial length of device. Visibility at the end of the device may also be limited. Some of the tissues along the airway are sensitive to energy- based treatments, such that inadvertent treatment or simply contact with a hot surface may cause significant complications. For example, a polyp may require removal from a vocal cord, the vocal cord being particularly sensitive to heat. The tissues or pathologies along the airway are generally small and therefore overtreatment, including applying excessive energy may generally be a risk. Some procedures require a combination of both fine dissection and some larger scale debulking, often requiring multiple devices for a single procedure. Devices may be provided with suction to remove fluids and treated tissue from the treatment site and improve overall visibility, the suction pathways prone to clogging due to the overall size limitations of the devices. Devices may alter in their tissue effect as the device orientation changes. Therefore, there is a need for a single device that addressed the shortcomings described above. There is a need for a single device that offers targeted tissue removal in narrow anatomies via electrosurgical treatment of tissue and offers a consistent tissue effect while in a variety of orientations. There is a need for a single device that provides access to narrow anatomies while providing increased surgical field visualization. There is a need for a single device that limits inadvertent tissue damage. There is a need for a device that accesses a plurality of pathologies along the airway, that may also offer a plurality of tissue treatment modes, such as fine dissection and debulking. PT-6149-WO-PCT SUMMARY An improved electrosurgical wand for treatment of a variety of pathologies along the patient airway, and more specifically tissues in and around the larynx. The improved wand may include a multifunctional treatment electrode that may both finely dissect tissues and / or debulk tissue. The wand, in cooperation with an electrosurgical controller may treat tissues by means of ablation as defined herein. A more detailed description of the ablation can be found in at least commonly assigned U.S. Pat. No. 5,697,882, the complete disclosure of which is incorporated herein by reference. This electrode may include a planar treatment surface configured to debulk tissue along the larynx, via ablation. This electrode may also include an edge surface and / or distally projecting tip configured to dissect the tissue along the larynx via ablation using a plasma. The wand may deliver an electrically conductive fluid to the target site and aspirate tissue, fluid and plasma by-products therefrom. The wand may be a handheld wand and thereby used directly by a clinician or may be configured to be controlled via a robotically controlled surgical setup. The wand may include improvements to suction openings and suction pathways to significantly reduce the potential for clogging the wand, as is prone to occur in related art wands. The wand may include improvements to fluid delivery to provide a consistent fluid delivery despite the wand orientation. An example bipolar electrosurgical wand embodiment disclosed herein may include a tubular end effector with an electrically insulative spacer, a return electrode and an active electrode at its distal end. The active electrode may define a longitudinal axis, a proximal portion and a single tip projection extending distally from the proximal portion. The proximal portion is coextensive with the insulative spacer, and the single tip projection extends beyond a distal-most surface of the insulative spacer. The single tip projection is defined by bilateral linear tapering edges that are coextensive with the insulative spacer and extend up to a distal-most end of the single tip projection. In some example embodiments the active electrode may include an aspiration opening extending therethrough, through both the proximal portion and the single tip projection. This aspiration opening may have a proximal curved end and may taper along PT-6149-WO-PCT as it extends along and through the single tip projection towards a distal curved end, such that the distal curved end is smaller or has a smaller radius, than a radius of the corresponding proximal curved end. This aspiration opening may taper along the single tip projection with bilateral linear tapering edges. These bilateral linear tapering edges may be parallel to the linear tapering edges of the single tip projection. In some example embodiments, the return electrode may include a fluid delivery aperture including a slot portion and a notch portion that extends distally therefrom. The slot portion and notch portion may be continuous with each other, and the notch portion may have a smaller circumferential width or lateral extent than a corresponding slot portion circumferential width or lateral extent. The insulative spacer may include a cavity ramp for directing a conductive fluid being delivered along the wand towards the fluid delivery aperture. The notch portion may be axially coincident with a distal-most end of the cavity ramp. A distal most edge of the notch portion may be coincident with a distal most edge of the cavity ramp. A distal most edge of the cavity ramp may be proximally spaced from the active electrode. In some example embodiments, the insulative spacer proximal end surface may define a ramped surface, the ramped surface may direct an electrically conductive fluid being delivery along the bipolar electrosurgical wand up towards the notch portion. This ramped surface and notch portion may cooperate to direct fluid in a distal direction towards the active electrode, despite wand orientation. Another example bipolar electrosurgical wand is disclosed herein including a tubular end effector with an electrically insulative spacer, a return electrode, and an active electrode at a distal end thereof. The insulative spacer may support and electrically insulate the active electrode from the return electrode. The active electrode may define a proximal portion and a tip projection, the tip projection defining an isosceles trapezoid shape extending distally from the proximal portion. The tip projection may have a central axis that lies on a plane that bisects the active electrode. The active electrode proximal portion may be coextensive with the insulative spacer, and the tip projection may extend beyond a distal-most surface of the insulative spacer. In some example embodiments, the active electrode may include an aspiration opening that extends along both the proximal portion and tip projection. This aspiration PT-6149-WO-PCT opening may have a proximal curved end and tapers along the tip projection towards a distal curved end that is smaller than the proximal curved end. The aspiration opening may taper along the tip projection with bilateral linear tapering edges. In some example embodiments, the return electrode may include a fluid delivery aperture including a slot portion and a notch portion extending distally therefrom. The slot portion and a notch portion are portions of the same aperture and are therefore continuous with each other. The notch portion may have a smaller circumferential width than a corresponding slot circumferential width. The insulative spacer may include a cavity ramp for directing a conductive fluid being delivered along the wand towards the fluid delivery aperture and wherein the notch portion may be coincident with a distal-most end of the cavity ramp. A distal most edge of the notch portion may be coincident with a distal most edge of the cavity ramp. A distal most edge of the cavity ramp maybe proximally spaced from the active electrode. In some example embodiments the insulative spacer proximal surface may define a ramped surface configured to direct a fluid being delivery along the bipolar electrosurgical wand up towards the notch. Another example bipolar electrosurgical wand is disclosed herein including a tubular end effector with an electrically insulative spacer, a return electrode, and an active electrode at a distal end thereof, the insulative spacer supporting and electrically insulating the active electrode. The active electrode defines a proximal portion and a tip projection extending distally from the proximal portion. The proximal portion is coextensive with the insulative spacer, and the tip projection extends distally therefrom and beyond a distal-most surface of the insulative spacer. The active electrode includes an aspiration opening that extends through the active electrode through both the proximal portion and the tip projection. The return electrode includes a fluid delivery aperture having a slot portion and a notch portion, that are continuous with each other to form the aperture. The notch portion extends distally from the slot portion and has a smaller circumferential width than the slot portion. The notch portion funnels a fluid being delivered through the fluid delivery aperture in a distal direction. These and other features and advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. It is to be PT-6149-WO-PCT understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed. NOTATION AND NOMENCLATURE Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, companies that design and manufacture electrosurgical systems may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to .... ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections. Reference to a singular item includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said” and “the” include plural references unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement serves as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Lastly, it is to be appreciated that unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. “Ablation” shall mean removal of tissue based on tissue interaction with a plasma. “Mode of ablation” shall refer to one or more characteristics of an ablation. Lack of ablation (i.e., a lack of plasma) shall not be considered an “ablation mode.” A mode which performs coagulation shall not be considered an “ablation mode.” “Debulking” shall refer to removing tissue using ablation. PT-6149-WO-PCT “Active electrode” shall mean an electrode of an electrosurgical wand which produces an electrically induced tissue-altering effect when brought into contact with, or close proximity to, a tissue targeted for treatment. “Return electrode” shall mean an electrode of an electrosurgical wand which serves to provide a current flow path for electrical charges with respect to an active electrode, and / or an electrode of an electrical surgical wand which does not itself produce an electrically induced tissue-altering effect on tissue targeted for treatment. Where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure will be more fully understood by reference to the detailed description, in conjunction with the following figures, wherein: FIG.1 illustrates an electrosurgical system in accordance with this disclosure; FIG.2 illustrates an example embodiment of an electrosurgical wand in accordance with this disclosure; FIG.3A illustrates a perspective view of an electrosurgical wand distal end in accordance with this disclosure; FIG.3B illustrates a top view thereof, perpendicular to an active electrode planar face of the electrosurgical wand in accordance with this disclosure; FIG.3C illustrates a side view thereof, in accordance with this disclosure; FIG.3D illustrates a perspective view of an underside thereof, in accordance with this disclosure; FIG.3E illustrates a partial cross section of the electrosurgical wand distal end, in accordance with this disclosure; FIG.3F illustrates a perspective view of the partial cross section of the electrosurgical wand distal end, in accordance with this disclosure PT-6149-WO-PCT FIG.3G illustrates a bottom view of the electrosurgical wand distal end, in accordance with this disclosure; FIG.3H illustrates another perspective view of the electrosurgical wand distal end, in accordance with this disclosure; FIG.4A illustrates an active electrode of the electrosurgical wand distal end, in accordance with this disclosure; and FIG.4B illustrates a cross section view of the active electrode of the electrosurgical wand distal end, in accordance with this disclosure. DETAILED DESCRIPTION In the description that follows, like components have been given the same reference numerals, regardless of whether they are shown in different examples. To illustrate example(s) in a clear and concise manner, the drawings may not necessarily be to scale and certain features may be shown in somewhat schematic form. Features that are described and / or illustrated with respect to one example may be used in the same way or in a similar way in one or more other examples and / or in combination with or instead of the features of the other examples. As used in the specification and claims, for the purposes of describing and defining the invention, the terms “about” and “substantially” are used to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “about” and “substantially” are also used herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. “Comprise,” “include,” and / or plural forms of each are open ended and include the listed parts and can include additional parts that are not listed. “And / or” is open-ended and includes one or more of the listed parts and combinations of the listed parts. Use of the terms “upper,” “lower,” “upwards,” and the like is intended only to help in the clear description of the present disclosure and are not intended to limit the structure, positioning and / or operation of the disclosure in any manner. PT-6149-WO-PCT Methods recited herein may be carried out in any order of the recited events, which is logically possible, as well as the recited order of events. Furthermore, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. In addition, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. All existing subject matter mentioned herein (e.g., publications, patents, patent applications and hardware) is incorporated by reference herein in its entirety except insofar as the subject matter may conflict with that of the present invention (in which case what is present herein shall prevail). The referenced items are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtue of prior invention. Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Last, it is to be appreciated that unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Referring to FIG.1, an exemplary electrosurgical system 11 for treatment of tissue in accordance with the present disclosure will now be described in detail. Electrosurgical system 11 generally comprises electrosurgical wand 10, hereinafter “wand”, that may be electrically connected to an electrosurgical controller (i.e., power supply) 28, hereinafter “controller”; the controller 28 general configured to provide a high frequency voltage to the wand 10 and thereby to a target tissue site. The system may also include a fluid PT-6149-WO-PCT source 21 for supplying electrically conductive fluid 50 to wand 10 via fluid delivery tube 15 / 16. Fluid delivery may be controlled by pump 40, to provide a controlled fluid flow supply to wand 10 via delivery tube 16. Pump 40 may be in communication (shown as dotted line) with controller 28, such that selection of different electrosurgical power supply modes (described in detail later) may also communicate instructions to the pump 40, to alter a parameter of the pump 40 and adjust the fluid delivery rate. Pump 40 is shown as a separate enclosure but may be part of the same enclosure as the controller 28. In addition, electrosurgical system 11 may include a scope (not shown), that may include a fiber optic head light for viewing the surgical site, particularly useful in procedures in the back of the mouth. The scope may be integral with wand 10, or it may be a separate object. The scope may be a laryngoscope. The system 11 may also include a suction or aspiration tube 42 that may be configured to couple to a vacuum source (not shown), such as wall suction. Tube 42 as shown may be associated with the wand 10 for aspirating tissue debris and fluid from the target site. Tube 42 may also be operatively coupled to a pump (not shown) for example, such as a peristaltic pump, to control an aspiration flow rate. Wand 10 generally comprises a handle 19 and an elongate tubular shaft 17 extending distally from handle 19. The handle 19 typically comprises a plastic material that is easily molded into a suitable shape for handling by the surgeon. As shown, a connecting cable 34 has a connector 26, and together they electrically couple the wand 10 to controller 28. Controller 28 may have an operator controllable energy / voltage level adjustment 30 to change the applied voltage level, which is observable at a display 32. Controller 28 may also include first second- and third-foot pedals 37, 38, 39 and a cable 36, which may be removably operatively coupled to controller 28. The foot pedals 37, 38, 39 may allow the surgeon to remotely adjust the voltage, mode or energy level applied to active electrode. In an exemplary embodiment, first foot pedal 37 may be used to direct the controller 28 to deliver energy to the wand 10 in the “ablation” mode and second foot pedal 38 may place electrosurgical controller 28 into a thermally heating mode (i.e., contraction, coagulation, or other types of tissue modification without volumetric tissue removal / debulking). Alternatively, second foot pedal may direct the electrosurgical controller to supply energy in a “blended” mode (blend of tissue removal or debulking and PT-6149-WO-PCT concomitant hemostasis). The third foot pedal 39 (or in some embodiments a foot- activated button) may allow the user to adjust the voltage level within the mode. In other embodiments, a series of hand switches along the wand handle 19 may replace at least some of the foot pedals. The electrosurgical system 11 of the various embodiments may have a variety of operational modes. One such mode may employ Coblation® technology. The assignee of the present invention owns and developed Coblation® technology. A more detailed description of this technology can be found in commonly assigned U.S. Pat. No. 5,697,882, 6,355,032; 6,149,120 and 6,296,136, the complete disclosure of which is incorporated herein by reference. The electrosurgical system 11 may include a blended mode wherein a blend of tissue debulking and thermal shrinkage may occur within the same mode. A more detailed description of this mode can be found in commonly assigned U.S. Patent 11,116,569, the complete disclosure of which is incorporated herein by reference. The electrosurgical system 11 may include a pulsing thermal mode wherein the tissue is thermally treated to coagulate and shrink the turbinate tissue, pulsing intermittently with an ablation output, wherein the ionized vapor formed may be configured to reduce tissue sticking. In the thermal heating or shrinking (coagulation) mode, the controller 28 may apply a sufficiently low voltage to the active electrode to avoid vaporization of the electrically conductive fluid and subsequent molecular dissociation of the tissue. The surgeon may automatically toggle the controller 28 between the ablation and thermal heating modes, by alternatively stepping on foot pedals 37, 38, respectively. This allows, for example, the surgeon to quickly move between coagulation and ablation in situ, without having to remove his / her concentration from the surgical field or without having to request an assistant to switch the controller. By way of example, as the surgeon sculpts or dissects soft tissue in the ablation mode, the wand typically may simultaneously seal and / or coagulation small, severed vessels within the tissue. However, larger vessels, or vessels with high fluid pressures (e.g., arterial vessels) may not be sealed in the ablation mode. Accordingly, the surgeon can simply step on foot pedal 38, automatically lowering the voltage level below the threshold level for ablation and apply sufficient pressure onto the severed vessel for a sufficient period to seal and / or coagulate the vessel. After this is PT-6149-WO-PCT completed, the surgeon may quickly move back into the ablation mode by stepping on foot pedal 37. By way of a second example, the surgeon may finely dissect nodes or polyps along the patient airway via an ablation mode and then coagulate any bleeders with a coagulation mode. In another example, the surgeon may fine dissect a portion of the vocal cord using a higher voltage Ablation mode during a Cordectomy and then reduce the voltage or chose a “coag” mode, to coagulate any resulting bleeders. In some procedures, the surgeon may select a high voltage ablation mode to debulk inflamed or scar tissue along the Subglottis to treat subglottic stenosis. Selecting each mode may also automatically adjust a fluid delivery rate to the wand distal end. For example, selecting the debulking mode(s) may also direct the controller 28 to operate the pump 40 to deliver fluid at a rate configured to support the target rate of debulking the tissue, and selecting a thermal heating mode may direct the controller 28 to operate the pump 40 to deliver fluid at a rate figured to support thermally heating the tissue. The fluid delivery flow rate for debulking may be higher than the fluid delivery flow rate for thermally heating. FIG.2 illustrates a side view of electrosurgical wand 10 constructed according to the principles of the present disclosure and configured to operate as part of system 11. As shown in FIG. 2, wand 10 generally includes an elongate shaft 17 and a handle 19 coupled to the proximal end of shaft 17. Handle 19 may comprise a plastic housing that is easily molded into a suitable shape for handling by the surgeon. Handle 19 defines an inner cavity that may house electrical cabling and connections (not shown). Housing may provide a suitable interface for connection to an electrical connecting cable, such as cable 34. Inner cavity may also house fluid conduits for aspiration and fluid delivery. Fluid inlet 216 may form a part of the fluid delivery conduit of the whole system, fluid delivery conduit defining a multi-component construct that is configured to deliver electrically conductive fluid 50 from the source 21 to the wand distal portion 120. Fluid inlet 216 may be fluidly coupled or fluidly couplable to tube 16. Fluid inlet 216 may be fluidly coupled by an operator to a tube 16, that may be provided separated from handle 19 and fluid supply source 50. In other example embodiments wand 10 may be provided with fluid delivery tube 16 pre-attached such that tube 16 may extend through inlet 216; inlet 216 defining an opening through the handle 19 for receiving tube 16 therethrough. Fluid delivery conduit may extend through handle 19 (not shown) and along shaft 17. PT-6149-WO-PCT Fluid delivery conduit may be defined by an inner bore surface of shaft 17. In some embodiments, wand 10 may also include a valve or equivalent structure (not shown) on the wand 10 or tubing 16, for controlling the flow rate of the electrically conducting fluid delivered to the target site. In other embodiments, as disclosed herein the flow rate may be controlled by pump 40. A fluid and debris aspiration conduit (hereinafter “aspiration conduit”) may also extend through an opening 242 in handle 19, aspiration conduit defining a construct configured to remove fluid and debris from the wand distal end 120 and away from the treatment site. Fluid aspiration conduit may extend from wand distal working end 120, to remove fluid and debris therefrom. Fluid aspiration conduit may be fluidly coupled to or selectively coupled to tubing 42 that may couple to a vacuum source. Fluid aspiration conduit may include a tube (not shown) that extends from the wand distal working end 120 proximally along the shaft 17 and handle 19 up to tube 42. A portion of the fluid aspiration conduit may extend through spacer 360 and can be seen in FIG.3E and FIG. 3F. Aspiration may be controlled manually via a switch 205 on the handle 19 that is in communication with a valve (either mechanically or electrically). In other embodiments aspiration may be automatically controlled via controller 28 and may automatically initiate or adjust a valve while energy is being delivered to the wand distal working end 120. Wand 10 is generally configured to improve access to tissues within a patient’s airway that may be adjacent the larynx, and therefore shaft 17 may include a bend or curve 201. Curve 201 may be closer to the handle 19 than distal working end 120. If we allocate the shaft to include a distal segment 17a and a proximal segment 17b, as shown, bend 201 may angularly offset the proximal shaft segment 17b at an angle α between 30- 55 angular degrees from a longitudinal axis (L-L) of the shaft distal segment 17a. This angular offset may improve access along the patient airway and visualization of the target area. More preferably the angle α may be approximately 35 degrees, as the inventors have found that this shallow angle may more precisely control the distal working end 120, while allowing some visibility of the projecting distal tip of active electrode (discussed in more detail hereinafter). Shaft distal segment 17a may be a working length (X) that extends through an inner opening of a laryngoscope and is sufficiently long to gain access to the target area, and may be at least 17cm long, as measured from an apex of the bend PT-6149-WO-PCT 201. In some preferred embodiments, the distal segment 17a may be approximately 25cm long, as this may improve subglottic access. Shaft 17 may be formed of annealed steel, to add elastic flexibility to the shaft for improved manipulation along the patient airway. FIGS.3A-3H show an example embodiment of a distal working end 120 of wand 10. Distal working end 120 may have a bipolar arrangement and include a return electrode 310 and an active electrode 330. An electrically insulative spacer 360 (hereinafter “spacer”) may support the active electrode 330 and electrically isolate the return electrode 310 from the active electrode 330. Spacer 360 may be formed of a plasma resistant ceramic and may also define a portion of the back side of distal end 120 (best seen in FIGS.3C, 3D and 3G). This may help thermally isolate the back or bottom side, as discussed in more detail, hereinafter. In general, the distal working end 120 left side is a mirror image of the right side, and therefore features shown on one side are not specifically shown in a figure but are inherently present. Distal working end 120 may be configured to treat tissue via plasma generation around the active electrode 330 which may therefore be formed of material or materials that are resistant to plasma degradation. Example materials include, but are not limited to, tungsten, titanium, molybdenum, stainless steel, aluminum, gold, copper or the like. Active electrode 330 may be a complex unibody with a variety of edges and surfaces, some of which are intended to control the tissue effect, and some of the edges and surfaces are intended to aid in resisting or mitigating clogging of the wand. In general, the volume and surface area of the active electrode 330 overall is minimized, thereby requiring a minimal amount of energy to treat the delicate structures along a patient’s airway. Being small in size also helps confine the overall profile of the wand distal end 120. The active electrode 330 may be formed as a single molded electrically conductive body. Return electrode 310 may be a tubular shaped conductive material, that may be an extension of and electrically exposed portion of shaft 17. Return electrode 310 may be formed of annealed stainless steel. Most of the shaft 17 may be covered with shrink tubing 370 formed of an insulating material, to limit the return electrode exposed surface area and avoid inadvertent tissue damage along the patient airway, proximal of the distal working end 120. Return electrode 310 may include a single aperture 312 therethrough PT-6149-WO-PCT that may be in fluid communication with the fluid delivery conduit extending along shaft 17. Fluid delivery conduit may be defined for a least a portion of its length by an inner lumen surface of the shaft 17. Fluid aperture 312 may be in fluid communication with fluid delivery tubes 15 / 16. Aperture 312 may therefore function as a fluid delivery aperture for delivering electrically conductive fluid 50 to external surfaces of the distal working end 120. Aperture 312 may define an elongate 360-degree bounded hole that may have a proximal oblong portion that has a longer dimension extending circumferentially around the tubular return electrode 310. Aperture 312 may be centered relative to a longitudinal axis of the working end 120. Aperture 312 includes a distally projecting notch 314, that may also be centered relative to a longitudinal axis of the working end 120. Notch 314 may have a circumferential opening width that is less than a corresponding circumferential opening width of the oblong portion of aperture 312. Notch 314 is configured to extend the aperture distally, and direct fluid flowing out of aperture 312 in a general distal direction and concentrate the flow it towards the active electrode 330. This notch 314 has been found to help direct the electrically conductive fluid distally and towards the active electrode 330 for a wider range of wand orientations than an elongate aperture absent a notch, helpful as the user manipulates the wand down the patient airway. The environment within the patient airway is semi-open and therefore may be somewhat dry, unlike arthroscopic procedures where wands or devices may be immersed in an electrically conductive fluid within a joint space. Therefore, this device relies upon a consistent supply of electrically conductive fluid around the distal end and on the active electrode 330, to form a consistent plasma. This notch 314 has been found to improve the supply consistency to the distal end, as the wand moves around in a range of orientations down the patient’s airway. Turning to FIGS.3E and 3F, that both illustrate a partial cross section of the wand distal end 120, spacer proximal most end 363 may define a transverse surface 365 and a ramped portion 364 extending distally therefrom. Ramped surface 364 may slope up towards the aperture 312 as it extends distally, and a distal most end of ramped surface 364 may be axially coincident with aperture 312. More specifically, a distal most end of ramped portion 364 may be located directly adjacent aperture notch 314. More specifically, a distal most end of ramped surface 364 may terminate at a location adjacent PT-6149-WO-PCT with a distal most end edge of notch 314, illustrated as line D-D. The ramped portion 364 defines a sloped surface located relative to the delivery aperture 312 and notch 314, to direct the fluid being delivered along the shaft 17 up through the aperture 312 and notch 314 and then distally along the external surfaces of the wand towards the active electrode 330; illustrated with arrows. The notch 314 and ramp surface portion 364 cooperate to maintain a distally flowing direction of fluid flow, for a variety of wand orientations. Spacer 360 may fill the shaft lumen. FIG.3E also illustrates a suction tube 388, that may extend through spacer 360, along and within the shaft 17, through the handle and may be fluidly coupled to suction or aspiration tubing. Return electrode 310 may also include a window 316 (best seen in FIG.3D and 3G) on the wand under side, that may receive a portion of the spacer 360 therethrough. This may reduce a thermal footprint of the return electrode 310 and may limit inadvertent thermal damage should adjacent tissue touch the back side of the wand distal end 120. Window 316 may extend for over half of the return electrode length. Window 316 may be coextensive with aperture 312 and may extend both proximally and distally further along the longitudinal axis of wand than the entire aperture 312. Window 316 may extend up to a distal end of tubing 370. Spacer 360 may be formed or coated with a ceramic that is a material that may act as a heat sink. Spacer 360 may include a radial projection 362 that extends through window 316 up to at least the circumferential outer-most surface of return 310, to provide a smooth continuous outer-most back surface between the return 310 and spacer projection 362. This may reduce snagging and provide a preferable contact surface to engage the adjacent tissues on the back side of the wand distal end 120, which may reduce inadvertent contact between this tissue and the return electrode 310. Window 316 may be bounded by bilateral arms 315a, 315b of return electrode 310, and each arm 315a, 315b may encircle a distal-most surface of spacer 360. Aperture 316 may be formed by obtaining the return electrode 310 with the bilateral arms 315a, 315b in a substantially straight or spaced apart orientation, configured to receive the spacer 360 therebetween. Spacer 360 may then be assembled and placed between the bilateral arms 315a, 315b, before plastically deforming the bilateral arms 315a, 315b towards each other and around a distal most surface of spacer 360. Return electrode 310 PT-6149-WO-PCT may therefore be formed of a readily plastically formable electrically conductive material, such as annealed stainless steel. Wrapping these arms 315a, 315b may place a portion of the return electrode 310 close the distal tip (340) of active electrode 330, while maintaining a small distal end wand profile. Having a portion of the return electrode (such as arms 315a, 315b) wrapped around a distal-most surface of spacer and directly adjacent distally projecting tip 340 of active electrode 330 (without making electrical contact) may help to initiate a rapid and uniform vapor layer and ultimately speed up plasma initiation at the projecting tip 340. Having the return electrode 310 directly under the projecting tip 340 may provide increased energy density directly between the active electrode projecting tip 340 and return electrode 310, helping to initiate more rapid plasma formation at the distal projecting tip 340. Having a proximity between the projecting tip 340 and return electrode 310 (and more specifically arms 315a, 315b) also eases the burden for sufficient electrically conductive fluid between the electrodes. This burden stems from having to flow sufficient electrically conductive fluid from the delivery aperture 312, proximal of the entire active electrode 330 all the way around to this distal facing surface and near the tip 340, which can be frustrated depending on a variety of factors. For example, fluid 50 may be drawn into the aspiration opening 380 located through the active electrode 330 before reaching this distal most surface, or this fluid 50 may fall away from the wand 10, depending on the orientation of the wand 10. Secondly, moving sufficient fluid from the delivery aperture 312 that is proximal of the entire active electrode 330 all the way around to this distal facing surface may take time, causing a frustrating time delay between actuating the fluid delivery and energy and the fluid reaching around to this distal facing surface and near the tip 340. As a reminder this fluid 50 is key to enabling plasma formation. Therefore, placing a return electrode 310 directly under and close to the active electrode tip 340 may ease the burden on supplying sufficient electrically conductive fluid in a reasonable time, to electrically bridge the two electrodes, required for forming uniform or consistent plasma. This reduced burden helps initiate a vapor layer more immediately after energy and fluid delivery actuation, ultimately providing plasma initiation in a reasonable time. PT-6149-WO-PCT In addition, having the return electrode 310 wrap around this distal end, enables the return electrode 310 to have direct contact with tissue closer to the target tissue. This forms a more concentrated and more uniform electric field around the distal radius, so when the wand distal surfaces touch tissue, there is less distance for some of the electrical current to travel through tissue. This results in more tissue cutting with ablation and less resistive heating of the tissue. This provides for fine tissue dissection by molecular dissociation, with reduced thermal spread. This is important for laryngeal applications, to limit inadvertent thermal damage to surrounding delicate airway anatomy. FIG.3C shows a side view of distal working end 120. Distal working end 120 may have a longitudinal axis A-A that is angularly offset by angle β from shaft longitudinal axis L-L. Angle β may be between 5-35 degrees and may more preferably be approximately 20 degrees to enable visibility of the target tissues within the patient airway, while also fitting within a laryngoscope opening. Active electrode 330 may define a top planar surface 331 that extends an angle Ω relative to working end longitudinal axis A-A. Angle Ω may be between 5 and 15 degrees. Angle Ω is configured to allow the operator to see the projecting tip 340 of the active electrode while treating tissues within the patient airway. Angle β may angularly offset the distal working end 120 and thereby active electrode planar surface 331 in a first direction relative to the longitudinal axis L-L and angle Ω may angularly offset the active electrode planar surface in a second direction, relative to the longitudinal axis L-L, the second direction opposite the first direction. FIG. 3B shows a top view of distal working end 120, perpendicular to active electrode planar top surface 331. Active electrode top surface 331 may be planar along its entire length (best seen in FIG.3C). During use, this planar surface 331 may be placed on the target tissue and upon application of electrosurgical energy, may debulk this target tissue. Active electrode 330 may include a 360-degree bounded aspiration opening 380 therethrough. Opening 380 may be axially coextensive with spacer 360. Active electrode 330 may include a proximal rectangular shaped portion 332 having sides that are parallel to the longitudinal axis of wand. Proximal portion 332 may define the widest portion of active electrode 330. Active electrode 330 may define an active electrode with a single projection. Extending directly from the rectangular shaped portion 332 is a single distally projecting tip 340. The projecting tip 340 has a top planar surface that forms a PT-6149-WO-PCT portion of the active electrode top surface 331. Stated another way, projecting tip 340 has a top planar surface continuous with and coplanar with rectangular portion top planar surface. A portion of the projecting tip 340 may be supported with spacer 360 and a portion of the projecting tip 340 may extend axially beyond spacer distal-most surface and be unsupported by spacer 360. Projecting tip 340 is generally configured to finely dissect a target tissue via a formation of plasma therealong and having the tip 340 project beyond the spacer 360 provides surfaces on a plurality of sides (up to 5 sides) of the projecting tip 340 that may better access and treat this target tissue. Projecting tip 340 may define a single projection with bilateral tapering edges 341 that are linear. Bilateral tapering edges 341 mirror each other relative to a plane that bisects the active electrode 330. Projecting tip 340 may be a single distal tip of the active electrode 330 and the bilateral tapering edges 341 may taper linearly along the entire length of the projecting tip. Having this linear taper has been found to provide preferred tissue energy-based dissection with minimal thermal spread or unwanted tissue hearing. Projecting tip 340 may define bilateral tapering edges 341 that define an isosceles trapezoid shape. The inventors have found that linear edges may be preferable over curvilinear tapering edges as curvilinear edges may reduce tissue dissection capabilities and / or increase thermal damage to other tissues. The aspiration opening 380 is disposed through both the proximal portion 332 and projecting tip 340. Aspiration opening 380 is configured to aspirate plasma by-products, partially digested tissue, and fluid therethrough, and is fluidly coupled to the fluid aspiration conduit of the system 11. More specifically, aspiration opening 380 may be in direct fluid communication with an aspiration cavity within the spacer 360, which is in direct fluid communication with a suction tube (not shown) that extends along the shaft 17. Aspiration opening 380 defines a complex opening that extends from the top planar surface 331 to a bottom end surface of active electrode 330, the opening 380 including several structural features that provide a sufficiently large opening for efficient aspiration of plasma by-products and partially digested tissue therethrough while reducing the likelihood of clogging with the partially digested tissue, along the aspiration conduit. Too large an aspiration opening may allow larger size tails or strings of partially digested tissue into the wand 10, that may clog the aspiration conduit. In addition, too large an aspiration PT-6149-WO-PCT opening has been found to form a central untreated core of tissue. However, too small an aspiration opening may limit aspiration completely, and leave the plasma by-products and partially digested tissue in the field. This complex opening is configured to provide sufficient opening size for effective aspiration, while managing the aspirated plasma by- products and partially digested tissue to avoid clogging. At least some of the means of managing the aspirated tissue to mitigate clogging includes means to further digest the partially digested tissue. This means is best described while viewing FIGS.4A and 4B. Consider first that as partially digested tissue enters the opening 380, some of this tissue may further interact with plasma formed along the inner surface wall 381 of opening 380 as this tissue flows along the opening 380. However, at a certain radial distance away from this inner surface wall 381 along and more central to opening 380, the partially digested tissue may not interact with any plasma. This forms or defines a plasma-remote zone 386 along the opening 380, that is remote from the inner surface wall 381 and thereby less effected by the plasma. Tissue debris that may include plasma by-products within the plasma-remote zone 386 may be too remote for further digestion as it is aspirated through the opening. Stated another way, as some tissue debris flows through the opening 380 radially spaced from inner surface wall 381, a central zone 386, that may be cylindrical may not be digested further via plasma. This can lead to clogging of the aspiration pathway. A first means to diminish this plasma-remote zone 386 and further digest this tissue is provided via angling the aspiration opening inner surface wall 381 so that it extends non-perpendicularly from the electrode top surface 331. This inner surface wall 381 may extend through the active electrode 330 defining a constant cross section therethrough, extending along a central axis (C) that extends at an incline relative to the planar top surface 331. The central axis C may extend along the longitudinal axis of the active electrode and proximally between 10 and 45 angular degrees (o) from an axis perpendicular to the top planar surface 331. More preferably, the central axis C may extend along the longitudinal axis of the active electrode and proximally between 15 and 30 angular degrees (o) from an axis perpendicular to the top planar surface 331. In some preferred embodiments, the central axis C may extend along the longitudinal axis of the active electrode and proximally approximately 20 angular degrees (o) from the axis PT-6149-WO-PCT perpendicular to the top planar surface 331. For thin and small electrodes, such as active electrode 330, the incline angle helps to mitigate clogging. The incline angle acts to increase the effective length of the inner surface walls 381, and thereby increase a length available for further debris digestion via interacting with the plasma formed therealong. Too sharp an angle (45 angular degrees or more), while adding more surface available to form plasma, may however also convolute the flow path through the opening 380, resulting in a higher risk of tissue clogging. To shallow an angle, may allow for more tissue to pass, but does not provide significant added benefit from further digestion via interacting of the plasma formed along wall or bore 381. This angled opening places a 360-degree edge boundary 385 on the top planar surface 331 axially offset from a corresponding 360-degree edge boundary 383 on a corresponding bottom surface of the active electrode 330. The central axis C (and thereby the aspiration opening wall) may incline so to extend proximally as the opening 380 extends through the active electrode 330 and away from the top planar surface 331, so that the edge boundary 383 on the bottom surface is proximally offset from the top surface edge boundary 385. This axial offset helps to reduce the effective diameter (or size) of zone 386, as the flow of tissue and debris is at least partially interrupted by the bottom surface edge boundary 383. The incline angle is configured to provide a larger overall opening dimension while limiting the plasma-remote zone 386. Aspiration opening 380 may be non-circular and may be shaped like a rounded wedge. Aspiration opening 380 may define a 360-degree bounded hole with a proximal- most curve 382 with a first radius of curvature that may be between 0.38-0.65mm, (R1), and a distal-most curve 384 (R2) with a second radius of curvature that may be between 0.15-0.25 mm. Two bilateral linear edges may extend linearly and proximally from the distal-most curve 384. In some embodiments, the ratio of R2 to R1 may be at least 1:3. In some embodiments the two bilateral linear edges may extend at least a 60 degree (angular) relative to each other. This aspiration opening shape provides a large opening (as defined by proximal-most curve 382) sufficient to remove sufficient tissue debris therethrough. The larger radius of curvature (R1) provides an increased opening size, while also providing a larger surface area for further digestion via plasma along this proximal-most segment of inner surface wall (381), as the aspirating tissue flows along PT-6149-WO-PCT the aspiration opening. The narrower apex 384 however limits a size of a distal side of the zone 386, and therefore reduces the plasma-remote zone cross section size 386. Tissue debris may enter the aspiration opening 380 at an angle approximately perpendicular to the top planar face 331, illustrated as arrow A. Therefore, as tissue debris enters the opening 380, it may be first digested at top surface edge boundary 385. Furthermore, tissue debris may be further digested as it interacts with plasma formed along the inner surface wall 381, including the inclined distal portion of inner surface wall 381. The inclined distal surface may increase the length of contact and thereby plasma interaction to improve tissue digestion. This incline may also deflect the flow of tissue debris though the aspiration opening 380 away from a distal most wall of the spacer cavity 366, to avoid the tissue debris from collecting there. This may direct flow of tissue debris proximally along the suction conduit. One skilled in the art will realize the disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing examples are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the disclosure is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

PT-6149-WO-PCT What is claimed is:

1. A bipolar electrosurgical wand, comprising: a tubular end effector having an electrically insulative spacer, a return electrode and an active electrode at a distal end thereof; wherein the active electrode defines a longitudinal axis and has a proximal portion and a single tip projection extending distally from the proximal portion, the proximal portion coextensive with the insulative spacer, the single tip projection extending beyond a distal-most surface of the insulative spacer, the single tip projection defined by bilateral linear tapering edges that are coextensive with the insulative spacer and extend up to a distal-most end of the single tip projection.

2. The bipolar electrosurgical wand of claim 1 wherein the active electrode includes an aspiration opening that extends along both the proximal portion and single tip projection.

3. The bipolar electrosurgical wand of claim 2, wherein the aspiration opening has a proximal curved end and tapers along the single tip projection towards a distal curved end that is smaller than the proximal curved end.

4. The bipolar electrosurgical wand of claim 3 wherein the aspiration opening tapers along the tip projection with bilateral linear tapering edges.

5. The bipolar electrosurgical wand of claim 1 wherein the return electrode includes a fluid delivery aperture including a slot and a notch extending distally therefrom and continuous with each other and wherein the notch has a smaller circumferential width than a corresponding slot circumferential width.

6. The bipolar electrosurgical wand of claim 5 wherein the insulative spacer includes a cavity ramp for directing a conductive fluid being delivered towards the fluid delivery aperture and wherein the notch is coincident with a distal-most end of the cavity ramp.

7. The bipolar electrosurgical wand of claim 6 wherein a distal most edge of the notch is coincident with a distal most edge of the cavity ramp.PT-6149-WO-PCT 8. The bipolar electrosurgical wand of claim 6 wherein a distal most edge of the cavity ramp is proximally spaced from the active electrode.

9. The bipolar electrosurgical wand of claim 5 wherein the insulative spacer proximal surface defines a ramped surface configured to direct a fluid being delivery along the bipolar electrosurgical wand up towards the notch.

10. The bipolar electrosurgical wand of claim 8 wherein the ramped surface and notch cooperate to direct fluid in a distal direction towards the active electrode, despite wand orientation.

11. A bipolar electrosurgical wand, comprising: a tubular end effector comprising an electrically insulative spacer, a return electrode, and an active electrode at a distal end thereof, the insulative spacer supporting and electrically insulating the active electrode; wherein the active electrode defines a proximal portion and a tip projection, the tip projection defining an isosceles trapezoid shape extending distally from the proximal portion, the tip projection having a central axis that lies on a plane that bisects the active electrode, and wherein the active electrode proximal portion is coextensive with the insulative spacer, and the tip projection extend beyond a distal-most surface of the insulative spacer.

12. The bipolar electrosurgical wand of claim 11 wherein the active electrode includes an aspiration opening that extends along both the proximal portion and tip projection.

13. The bipolar electrosurgical wand of claim 12, wherein the aspiration opening has a proximal curved end and tapers along the tip projection towards a distal curved end that is smaller than the proximal curved end.

14. The bipolar electrosurgical wand of claim 13 wherein the aspiration opening tapers along the tip projection with bilateral linear tapering edges.

15. The bipolar electrosurgical wand of claim 11 wherein the return electrode includes a fluid delivery aperture including a slot and a notch extending distally therefrom andPT-6149-WO-PCT continuous with each other and wherein the notch has a smaller circumferential width than a corresponding slot circumferential width.

16. The bipolar electrosurgical wand of claim 15 wherein the insulative spacer includes a cavity ramp for directing a conductive fluid being delivered towards the fluid delivery aperture and wherein the notch is coincident with a distal-most end of the cavity ramp.

17. The bipolar electrosurgical wand of claim 16 wherein a distal most edge of the notch is coincident with a distal most edge of the cavity ramp.

18. The bipolar electrosurgical wand of claim 16 wherein a distal most edge of the cavity ramp is proximally spaced from the active electrode.

19. The bipolar electrosurgical wand of claim 15 wherein the insulative spacer proximal surface defines a ramped surface configured to direct a fluid being delivery along the bipolar electrosurgical wand up towards the notch.

20. A bipolar electrosurgical wand, comprising: a tubular end effector comprising an electrically insulative spacer, a return electrode and an active electrode at a distal end thereof, the insulative spacer supporting and electrically insulating the active electrode; wherein the active electrode defines a proximal portion and a tip projection extending distally from the proximal portion, the proximal portion coextensive with the insulative spacer and the tip projection extending distally therefrom and beyond a distal- most surface of the insulative spacer; wherein the active electrode includes an aspiration opening that extends along both the proximal portion and tip projection; and wherein the return electrode includes a fluid delivery aperture having a slot and a notch continuous with and distally extending therefrom and wherein the notch has a smaller circumferential width than the slot and is configured to funnel a fluid being delivered through the fluid delivery aperture in a distal direction.

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