Patent Publication Number: US-8979842-B2

Title: Wire electrode devices for tonsillectomy and adenoidectomy

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/495,853, filed Jun. 10, 2011, the contents of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The field is electrosurgery, and in particular, tonsillectomy and adenoidectomy. 
     BACKGROUND 
     The tonsils and adenoids are generally located in the back of the human (mammalian) nose and throat, and are part of the lymphatic system that samples bacteria and viruses entering the body. Once sampled, the immune system is activated to produce antibodies that fight infection. When bacteria and viruses become trapped in the tonsils and adenoids, these tissues are able to break down their cell wall and deliver the fragments to areas of the body that produce antibodies modeled against the fragments. However, repeated inflammation of the tonsils and adenoids impedes their ability to destroy the bacteria that become entrapped therein, resulting in bacterial colonization of these tissues. The colonies of bacteria can then serve as a reservoir for repeated infections (e.g., tonsillitis or ear infections). Tonsillectomy and/or adenoidectomy may be indicated when antibiotic treatment fails to remove the bacterial reservoir. Tonsil tissue may also need to be removed if it enlarges to the point of causing airway obstruction, which may manifest as snoring or sleep apnea. Some individuals are also born with larger tonsils that are more prone to cause obstruction. Adenoidectomy may also be required to remove adenoid tissue when ear pain persists, or when nose breathing or function of the Eustachian tubes is impaired. 
     The devices and techniques used for tonsillectomy and adenoidectomy will usually depend on such factors as the type and amount of tissue to be removed and surgeon preference. The two procedures are routinely performed together. A common method for tonsillectomy and adenoidectomy employs cold surgical dissection. Here tissue is removed using a scalpel or other sharp instrument such as a curette or punch device. Sharp dissection oftentimes results in heavy bleeding, which can be stemmed with electrocautery. 
     In addition to coagulation, electrosurgery devices (e.g., suction-tipped, blade, or needle tip Bovies) may also be employed to resect tonsil or adenoid tissue. The suction tipped Bovie typically has a hollow center to suction blood, secretions, and smoke from the surgical field, and a rim of metal for cutting and coagulation. A separate aspirator is used when blade and needle tip Bovies are used. Although the use of Bovies reduces blood loss intraoperatively in comparison to cold techniques, it is associated with increased postoperative pain due to spread of the thermal injury from the heat of electrosurgery (average temperatures are above 300° C.). Despite their increased thermal injury profile, use of the Bovie remains the most popular method of tonsil removal in the U.S. due to its speed, convenience, universal availability, and surgeon familiarity with the device. 
     Other energy-type devices have been commercialized that attempt to minimize thermal injury. These include the Harmonic Scalpel® system (Ethicon Endo-Surgery, Cincinnati, Ohio) (ultrasonic energy), lasers (e.g., KTP, Nd:YAG, or CO 2  lasers), and Coblation® devices (Arthrocare, Austin, Tex.) (bipolar radiofrequency ablation). However, the decrease in thermal injury provided by these devices is questionable. Even if they do result in less thermal injury, it is offset by reduced control of bleeding and surrounding tissue trauma, longer operative times, or less precise cutting. Some of the instruments also obscure the surgical field and are difficult to maneuver due to their large size. 
     When Coblation® devices are employed, the procedure requires saline delivery in order to establish an electrosurgical effect. Pre-operative time is prolonged due to the inclusion of the saline delivery set-up. Coblation® device aspiration lumens also periodically clog during the procedure, which causes saline to pool in the patient&#39;s throat. The pooled saline must then be suctioned using a separate aspirator. Additionally, the Coblation® device lumen typically has to be manually cleared in order to finish the surgery. 
     Accordingly, new devices for resecting tonsil and adenoid tissue would be useful. In particular, devices that precisely cut tonsil and adenoid tissue while effectively controlling bleeding and surrounding tissue trauma would be desirable. Devices that provide easier access to the tonsils and adenoids and manipulation of those tissues would also be desirable. 
     SUMMARY 
     Described here (but not limiting) are electrically “monopolar” electrosurgical devices that optimize many functions required in performing tonsillectomy or adenoidectomy while minimizing side-effects (the return electrode is applied to the patient remote from the active electrode). For example, the precise cutting of tissue is provided by a thin layer of plasma that surrounds the electrode edge. In some instances the plasma is formed with pulsed radiofrequency (RF) energizing waveforms having a lower range of duty cycles so that tissue has time to cool between pulses. This coupled with the mostly insulated tips helps to reduce thermal damage by limiting the extent of thermal diffusion from the electrode into surrounding tissue. Continuous or 100% duty cycle energizing waveforms may also be employed when faster cutting is desired. When hemostasis is needed, suction and plasma may be directly applied to the target area to mechanically and electrically stop the bleeding. Tension of the electrode surface(s) against the tissue is generally optimized with a configuration where suction is applied through the electrode or in very close proximity thereto. The aspiration port being closely associated with the blade allows a “dry field” surgical technique. This is advantageous here because it allows a concave blade to function well unlike the case with a wet field. This is because current flows from the blade to the tissue only via the part of the blade in actual tissue contact with the dry field. Further, the suction decreases the width of the tissue in contact with the blade, further reducing the contact area and also further drying the tissue. Given that it may be difficult to access the portions of the oropharynx and nasopharynx where the tonsils and adenoids are located, the devices described herein may be designed with one or more malleable portions so that they can be shaped to improve access to these regions and/or accommodate variations in patient anatomy. 
     It has been found that for ENT (ear-nose-throat) surgery as described here, a monopolar approach is advantageous because the remote return electrode guarantees good electrical contact. In contrast, given the nature of such energizing, a bipolar device with both electrodes on one shaft makes good electrical contact for the return electrode difficult. 
     The electrosurgical devices generally include an elongate body having a proximal end, a distal end, and an aspiration lumen extending therethrough, an interchangeable tip removably attached to the distal end of the elongate body, and a handle at the proximal end of the elongate body where control mechanisms for cutting and coagulation are located. The interchangeable tip typically also has a proximal end, a distal end, and a tip lumen that is fluidly connected to the aspiration lumen of the elongate body. A housing that is secured to the distal end of the interchangeable tip will usually have an aperture and an integrated blade assembly, e.g., an electrode assembly, that includes an active electrode. The phrases “blade assembly” and electrode assembly” are used herein interchangeably. In some variations, the active electrode is a wire or loop electrode. The blade assembly or portion thereof may define an aspiration port that communicates with the aperture of the housing. 
     The devices generally include a connector at the proximal end of the interchangeable tips for removably attaching them to the elongate body. In some variations, the connector comprises a compressible barrel and one or more tabs that are located circumferentially around the connector. The compressible barrel may be inserted into the distal end of the elongate body to create a friction fit between the components and to thereby removably attach them to one another. The one or more tabs may be used to attach an ergonomic finger grip to the connector that may make insertion and removal of the interchangeable tip easier. 
     The interchangeable tips may be specifically configured for adenoidectomy or tonsillectomy. For example, when adenoidectomy is to be performed, the devices may include a blade assembly that optimizes tissue removal using a raking motion. Here the blade assembly may include an active electrode that has a cutting edge and a flat coagulation surface. A plurality of arms extending from the active electrode may secure the active electrode to the housing. The arms may have an angle that positions the cutting edge against the tissue in a manner that allows it to be easily and precisely scooped or shaved into the aspiration port. The particular arm angle may also be useful in achieving hemostasis by optimizing the position of the coagulation surface against the tissue. Alternatively, the electrode is a wire electrode. 
     When tonsillectomy is to be performed, the devices may include a blade assembly having a curved and tapered active electrode. This curvature may result in a more precise tonsil resection because the electrode surface approximately conforms to the contour of tonsil tissue. The curved and tapered electrode may also define an aspiration port therethrough. Here bleeding may be more effectively controlled since suction may be applied directly through the aspiration port of the electrode when the device is in the coagulation mode. This would combine mechanical pressure with plasma coagulation to achieve hemostasis. 
     The interchangeable tips may also be configured to be malleable so that their shape can be tailored to navigate access to the tissues or accommodate variations in patient anatomy. In some instances the interchangeable tips may be made for single use. Kits including one or more interchangeable tips are also contemplated. 
     Methods for resecting tonsil or adenoid tissue may generally include applying a pulsed electrical signal to the active electrode of the devices described herein to form a plasma on the active electrode, and cutting or coagulating the tissue with the plasma. In some variations, suction is applied simultaneously with proximal movement of the electrode to suction cut the tissue. In other variations, the tissue is coagulated while suction is simultaneously applied. In yet further variations, the methods will include exchanging one interchangeable tip, e.g., a tonsillectomy tip, with another interchangeable tip, e.g., an adenoidectomy tip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  depicts a side view of an exemplary electrosurgical device with an adenoidectomy tip. 
         FIG. 1B  depicts an expanded side view of the adenoid tip shown in  FIG. 1A . 
         FIG. 1C  is an expanded perspective view of the blade assembly shown in  FIGS. 1A and 1B . 
         FIG. 1D  shows the components of the housing in  FIGS. 1A and 1B  and how they are joined to integrate the blade assembly of  FIG. 1C . 
         FIG. 1E  is an expanded side view of the blade assembly shown in  FIGS. 1A-1D . 
         FIG. 1F  shows an expanded inferior view of an exemplary housing and blade assembly for adenoidectomy. 
         FIG. 1G  depicts a variation of the cutting edge that may be used in the blade assembly for adenoidectomy. 
         FIG. 2A  depicts an exemplary housing and blade assembly for tonsillectomy. 
         FIG. 2B  shows the components of the housing in  FIG. 2A  and how they are joined to integrate the blade assembly also shown in  FIG. 2A . 
         FIG. 3  is an inferior view (showing the bottom surface) of an exemplary adenoid tip including a wire as the active electrode. 
         FIGS. 4A and 4B  depict in various views the two main components of the housing shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Described here are electrosurgical devices that can be customized for either adenoidectomy or tonsillectomy. Customization may be provided by the use of interchangeable tips that can be removably attached to the elongate body of the device. Specifically, the design of the blade assemblies and location of the aspiration port from which suction is applied may be varied to optimize manipulation, cutting, and hemostasis of the tissue being operated on. 
     The present electrosurgical devices are generally monopolar instead of bipolar. Both types of devices use high frequency alternating current and a pair of electrodes, one designated the active electrode and the other the return electrode. However, the difference lies in the placement of these electrodes. In a monopolar device, current is passed from the active electrode through the patient&#39;s body to a grounding pad (return electrode) placed on the body, usually the thigh or shoulder. A monopolar device may be particularly useful in tonsil and adenoid surgery because contact with the body is guaranteed. In a bipolar device, the active and return electrodes are both placed at the site of electrosurgery, for example, on the same shaft of the device, and electrosurgery occurs only on the tissue on the active electrode(s) if there is a conductive path back to the return electrode. 
     The devices will generally include an elongate body having a proximal end, a distal end, and an aspiration lumen extending therethrough. Depending on the materials used, all or a portion of the elongate body may be formed to be stiff, flexible, or malleable. Exemplary materials for making the elongate body include, without limitation, fluoropolymers; thermoplastics such as polyetheretherketone, polyethylene, polyethylene terephthalate, polyurethane, nylon, and the like; and silicone. Another material is fluoroelastomer. 
     The elongate body may be between about 5.0 cm to about 20 cm in length. For example, the elongate body may be between about 5.0 cm to about 15 cm, between about 5.0 cm to about 10 cm, or between about 5.0 cm to about 8.0 cm in length. In some instances, the elongate body may be about 8.0 cm in length. In other instances the devices lack an elongate body, and the interchangeable tip is directly connected to the handle. 
     In some variations, the elongate body is coated with a lubricious polymer to reduce friction between the mucosa and device during the procedure. Lubricious polymers are well known in the art, and are typically hydrophilic. Exemplary hydrophilic polymers that may be used as lubricious coatings include, without limitation, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, cellulosic polymers and polyethylene oxide. 
     A handle is usually coupled to the proximal end of the elongate body that allows the surgeon to hold the device. The handle may include a hand grip on the bottom and a pad with at least two control buttons on the top. The control buttons may be depressed to activate electric switches for turning on the cutting or coagulation regimes. The button pad and hand grip are incorporated into the handle using spring clips or other well-know attachments and conventional techniques such as overmolding. A standard electrical connector and cable may be used with the handle to connect electrical leads to a generator. The handle may be between about 5.0 cm to about 30 cm, about 5.0 cm to about 25 cm, about 5.0 to about 20 cm, or about 5.0 cm to about 15 cm in length. In one variation, the handle is about 20 cm in length. 
     The aspiration lumen of the elongate body continues through the handle to a suction connector, which in turn connects tubing to a collection canister. The dimensions of the handle may be varied such that it is comfortably held in a hand, yet able to be manipulated during tonsillectomy and adenoidectomy. In some variations, the handle may be made for single use. As used herein, the term “suction handle” shall refer to the handle when coupled to the elongate body. 
     An interchangeable tip, as further described below, may be removably attached to the distal end of the elongate body. The interchangeable tip will typically have a proximal end, a distal end, and a tip lumen that is fluidly connected to the aspiration lumen to allow continuous flow of fluids, tissue, smoke, etc. away from the surgical field. The length of the interchangeable tip varies, but may be from about 1.0 cm to about 15 cm. For example, the adenoidectomy tip may be between about 5.0 cm to about 10 cm, and the tonsillectomy tip may be from about 1.5 cm to about 5.0 cm. In one variation, the adenoidectomy tip is about 9.0 cm. In another variation, the tonsillectomy tip is about 2.5 cm. The materials used to make the elongate body may also be employed in forming the interchangeable tip. 
     In one variation, the interchangeable tip is malleable. Malleability may be provided by wires running through the wall of the elongate body that are capable of being shaped by bending the elongate body. For example, the wires may be made from stainless steel or alloys thereof, nickel-titanium alloy, etc. Malleability may also be provided by forming the elongate body or portions thereof with metals or polymers that can be shaped. In some variations, joints or hinges are included. By having the ability to manipulate the shape of the interchangeable tip, it may be easier and quicker to access the tonsils and adenoids with the devices and easier to accommodate anatomical variations in that area. The interchangeable tips may be bent directly, e.g., by finger manipulation, or remotely through cables or wires using mechanisms commonly employed with steerable catheters. The interchangeable tips may be designed for single use. 
     The devices generally include a connector at the proximal end of the interchangeable tips for removably attaching them to the elongate body. An ergonomic finger grip may be used on the connector that may ease insertion and removal of the interchangeable tip. In some variations, the interchangeable tip may be configured to rotate about the connector. The connectors may be configured to removably attach to the elongate body by friction fit mechanisms. For example, they may include a compressible component that has a larger diameter when not connected to the elongate body. Compression of the component typically allows it to be slidingly engaged with the elongate body at which point the component is capable of expanding to its uncompressed diameter against the internal wall of the elongate body. In one variation, the connector comprises a compressible barrel and one or more tabs that are located circumferentially around the connector. The compressible barrel may be inserted into the distal end of the elongate body to create a friction fit between the components and to thereby removably attach them to one another. The one or more tabs may be used to attach an ergonomic finger grip to the connector that may make insertion and removal of the interchangeable tip easier. 
     Connection between the elongate body and interchangeable tip may also be supplied by locking-unlocking mechanisms. For example, the interchangeable tip may include a groove or channel, e.g., a L-shaped channel, in its wall configured so that upon receipt of a pin or other protrusion on the elongate body, the interchangeable tip may be rotated to be locked in placed. Other tongue-and-groove type locks and mechanisms including depressible pins or tabs are also contemplated. 
     The electrosurgical devices described here also generally include a housing at the distal end of the interchangeable tip for holding and securing the blade assembly thereto. The housing may be a single unit component or be made from multiple components. For example, the housing may be made by pressing together two components, an upper portion and lower portion. In some variations, the housing is configured with a blunt nose. In other variations, the housing is designed with a taper. 
     The housing may include an aperture through which suction can be applied to the tissues. The aperture may be of any shape and size so long as it provides an opening for aspiration of smoke, tissue, fluids, etc. For example, the aperture may be spherical, elliptical, egg-shaped, rectangular, triangular, diamond-shaped, or heart-shaped. These shapes are not meant to be limiting. When tissue is to be aspirated, the aperture may be larger than conventional suction openings. For example, the aperture may have a diameter from about 0.1 cm to about 1.0 cm. In some variations, the aperture diameter is larger than about 0.4 cm or about 0.5 cm. 
     In addition, the housing may be made from transparent materials or include a marker to aid visualization or provide an electrode locator in the surgical field. Materials with suitable transparency are typically polymers such as acrylic copolymers, acrylonitrile butadiene styrene (ABS), polycarbonate, polystyrene, polyvinyl chloride (PVC), polyethylene terephthalate glycol (PETG), and styrene acrylonitrile (SAN). Acrylic copolymers that may be particular useful include, but are not limited to, polymethyl methacrylate (PMMA) copolymer and styrene methyl methacrylate (SMMA) copolymer (e.g., Zylar 631® acrylic copolymer). 
     A blade assembly may be integrated within the housing, and generally includes the active electrode. The active electrode typically defines a cutting edge. The edge, however, is not like that of an ordinary knife which does the cutting solely via mechanical application to the tissue being cut. Instead here the edge of the electrode focuses the electric field induced by the applied electrical signal. This field that is concentrated at the edge generates a local plasma discharge. In some instances, the edge is formed by the onlay of metal foil. The tissue cutting may be assisted by mechanical force supplied by the edge of the electrode, as in conventional cutting, or by application of suction. 
     The active electrode may be made from any material having suitable electrical properties. For example, the active electrode may include without limitation, metals such as molybdenum, nickel, platinum, stainless steel, tantalum, titanium, tungsten, and alloys thereof. Thickness of the active electrode may be from about 0.1 mm to about 1.0 mm thick with an edge of about 10 μm to about 70 μm in thickness. In one variation, the active electrode thickness is about 0.25 mm (0.01 inch). In another variation, the thickness is about 0.025 mm (0.001 inch). The active electrodes may be etched or stamped or machined out of a large sheet of metal, which has been annealed for hardness. The electrodes may be made from layers, or multiple metals, alloys, or in part from non-conductive materials. 
     An electric insulating layer may be overlaid upon the active electrode to mostly cover it but leaving an exposed edge or surface that would be used for cutting or coagulation. The insulation is typically a coating of glass or ceramic approximately 0.005 mm to 0.5 mm thick, or in some instances approximately 0.01 mm to 0.2 mm thick. When glass insulation is used, it may be applied by a conventional process of dipping each relevant component prior to assembly in liquid (molten) glass and then annealing the glass. The glass insulation may also be applied by spraying. 
     The configuration of the blade assembly may vary depending on the intended use of the electrode. For example, technical features that enhance removal of adenoid tissue may differ from other features of interest in tonsillectomy. These design features are further elucidated below. 
     Adenoidectomy Tip 
     Adenoid tissue, which lies at the back of the nose/throat, may be removed through the mouth or nose, but typically through the mouth under general anesthesia. Thus, not only are the adenoids difficult to get to, but the presence of an endotracheal tube further cramps an already limited surgical field. The adenoid tips described here are interchangeable tips specifically configured to address many of these difficulties with adenoidectomy. 
     In one variation, as illustrated in  FIG. 1A , electrosurgical device  100  includes an elongate body  102  having a proximal end  104  and a distal end  106 . Proximal end  104  is coupled to a handle  108  where a finger grip  110  and pair of control buttons  112  are located. Adenoid tip  114  also has a proximal end  116  and a distal end  118 , and is removably attached to the elongate body distal end  106  by a connector  120  positioned at the elongate body distal end  106 . Here connector  120  includes a compressible basket  121  that can be depressed and slid into the distal end of the elongate body where it will then decompress to expand and create a friction fit against the internal wall of the elongate body ( FIG. 1B ). The elongate body  102  may be permanently or removably attached to the handle  108 , but will typically be permanently attached. Adenoid tip  114  is malleable and can be bent, as shown in  FIG. 1A . Here the adenoid tube  122  comprises a flexible material such as polyurethane, and includes two lumens (not shown) within its wall where bendable wires (not shown) run longitudinally between the adenoid tip distal end  118  and proximal end  116 . Additional lumens and wires may be employed as desired. 
     Although shown as bent upwards, the adenoid tip may be bent in other directions, so long as the device materials or functionality is not compromised. For example, the adenoid tip may be bent to form an angle with the elongate body of up to about 45°, up to about 60°, or up to about 90° or more with respect to the horizontal axis of the elongate body. Adenoid tip  114  may also be rotated to any angle about the axis of the connector  120 . As previously mentioned, the bendable nature of the adenoid tip allows easier access to the adenoids. It also provides more precise positioning of the active electrode. 
     The adenoid distal tip also includes a housing for holding the blade assembly. As shown in  FIGS. 1B and 1D , housing  124  is comprised of an upper portion  126  and a lower portion  128  that integrate a blade assembly  130  when both portions are joined together. Upper  126  and lower  128  portions may be joined by snap fitting, adhesives, welding, etc. The lower portion  128  may have an aperture  132  that defines an aspiration port  152  when the blade assembly  130  is integrated into the housing  124 . In some variations, the housing may be formed using a single component instead of a plurality of components. 
     As shown in the enlarged housing-blade assembly of  FIG. 1F , the housing  124  and integrated blade assembly  130  may define an aspiration port  152 , as explained above, through which suction is applied to aspirate fluids and smoke. However, the aspiration port  152  will generally also be dimensioned so that the device is capable of aspirating tissue through the port. In such instances, the port in cross-section may be spherical, ellipsoid, egg-shaped, rectangular, triangular, diamond-shaped, or heart-shaped, and thus wider than conventional suction openings. Here the aspiration port is about 0.1 cm to about 1.5 cm along its major axis and about 0.1 cm to about 1.0 cm along its minor axis. It is understood that these dimensions are exemplary and not limiting. 
     Bringing the upper and lower housing portions together with the blade assembly therebetween integrates the blade assembly into the housing. Here the housing is made from a transparent polymer such as Zylar 631® acrylic copolymer (SMMA copolymer) so as not to block visualization at the adenoid tip distal end  118 . Although not shown here, a marker can also be included on the surface of upper housing portion  126  to indicate the blade location underneath. 
     Turning to  FIG. 1C , blade assembly  130  includes an active electrode  136  having a cutting edge  138  and a coagulation surface  140 . A plurality of arms  142  having a first portion  144  and a second portion  146  secure the active electrode  134  to the housing  124 . The arms may be secured to the housing with medical grade adhesives such as cyanoacrylate or epoxy adhesives, and other adhesives, which are well known. Referring to  FIG. 1E , first  144  and second  146  arm portions form an angle  148  of about 110° to about 140°. In one variation, a 120° angle is defined between the first  144  and second  146  portions. This angle may optimize opposition of the coagulation surface  140  onto tissue to effectively achieve hemostasis. Further, the angle  148  may optimize the point of contact of plasma to the tissue from the cutting edge  138  to effect a more precise cut as well as resection of tissue while minimizing clogging of the aspiration port. 
     In another variation, as shown in  FIG. 1G , the cutting edge  138  may be shaped to include a leading edge  154 . The leading edge may aid initiation of plasma cutting and more effectively remove adenoid tissue. In some variations, the leading edge may extend about 0.2 mm to about 2.0 mm from the cutting edge. 
     After the blade assembly is integrated into the housing, cutting edge  138  defines an aspiration port  152  with the aperture  132 . With this adenoid tip configuration, cut adenoid tissue is directly and immediately suctioned into the aspiration port. Thus, proximal movement (movement toward the operator) of the adenoid tip while simultaneously maintaining suction may result in shaving strips of tissue. 
     Some variations of the adenoid tip include a wire as the active electrode. Compared to the other electrode configurations described herein, use of a wire electrode may particularly improve the cutting performance of the adenoid tip. This is because the decreased surface area of the wire generally produces less eschar build up, and thus, less sticking of tissue to the electrode. Furthermore, given that cutting is quicker with a wire electrode, contact of the wire electrode with adenoid tissue is less, resulting in decreased thermal injury to the adenoid tissue in comparison to the electrode configuration depicted in  FIGS. 1A-1G  (see Example 2). Another advantage of the wire design, e.g., instead of using the active electrode shown in  FIGS. 1A-1G , is that it allows greater freedom of movement during the adenoidectomy procedure. For example, with the active electrode depicted in  FIGS. 1A-1G , adenoid tissue would have to be approached at a specific angle because cutting of the tissue can only be made effectively when made perpendicular to the adenoids. Given the limited operative field, exposure of the adenoids is already difficult. Limiting the angle of approach would thus further frustrate the procedure. When a wire electrode is employed in the electrode assembly, cutting is not orientation specific. Another benefit is that a wire electrode is generally easier to manufacture than the active electrode of  FIGS. 1A-1G . 
     The wire may be completely embedded within the material of the housing except for the portion that extends across the housing aperture at the distal end of the adenoid tip. The wire may be embedded by overmolding the wire into a slot provided in the housing. Seating the wire in the slot may also recess the wire a certain distance from the distal end of the adenoid tip. For example, the wire may be recessed from the distal end of the adenoid tip a distance ranging from about 0.0005 inch (0.013 mm) to about 0.20 inch (5.1 mm). The wire may be of any suitable geometry, but will typically be round or circular in cross-section, and have a diameter ranging from about 0.008 inch (0.20 mm) to about 0.010 inch (0.25 mm). In another variation, the diameter ranges from about 0.005 inch (0.0125 mm) to about 0.020 inch (0.5 mm). In one variation, the wire has a diameter of about 0.008 inch (0.20 mm). 
     As previously stated, the housing may be of any suitable dimension and geometry. However, when a wire electrode is used, the housing configuration shown in FIGS.  3  and  4 A- 4 B may be particularly suitable. Referring to  FIG. 3 , adenoid tip  300  includes a housing  302  having a triangular shaped aperture  304 . A wire electrode  306  extends across the aperture  304  at the distal end  308  of the adenoid tip  300 . The wire electrode  306  is fully encapsulated, i.e., there is no exposed metal, within the material of the housing except for the portion that extends across the aperture  304 . Wire electrode  306  is seated in a slot  310  so that the exposed portion of the wire electrode  306  is recessed from the distal end  308  of the adenoid tip  300 . 
     Housing  302  is comprised of an upper portion and lower portion, as better shown in respectively  FIGS. 4A and 4B . In  FIG. 4A , upper portion  312  (shown in perspective in the upper left part of the figure) has a length of about 0.440 inch (11.18 mm) and is configured to be tapered toward its distal end  308 . The taper (shown in the side view, upper right of the figure) extends over a distance of about 0.315 inch (8.0 mm). As shown in the cross-section (lower right in the figure) taken along line A-A, the width of an opening at the distal end  308  is about 0.200 inch (5.1 mm).  FIG. 4B  shows the lower portion  316  of housing  302  (in an x-ray view, left part of the figure). Here the wire  306  is embedded within the material of the housing lower portion  316  except for the part that extends across triangular shaped aperture  304 . The wire  306  is also shown recessed a small distance from the distal end  308 . The length of housing lower portion  316  may be about 0.315 inch (8.0 mm). The aperture  304  may be about 0.144 inch (3.7 mm) in length and about 0.170 inch (4.3 mm) in width (at its widest part) (shown in side view, upper right of the figure). The wire  306  will usually extend across the aperture  304  at or near its widest part. Accordingly, in  FIG. 4B , the exposed portion of the wire is about 0.170 inch (4.3 mm) long. The housing  302  will generally be configured with a profile suitable for accessing and operating on the adenoids. Is some variations, and as shown in the cross-section (lower right of the figure) taken along line A-A in  FIG. 4B , the lower portion of the housing  316  has a smooth, gradually tapering profile. 
     The upper portion  312  and lower portion  316  are brought together to make the housing  302 . The upper and lower portions may be joined by methods previously described. It is understood that features such as tabs, pins, barbs, hooks, etc., and their corresponding grooves, channels, depressions, and the like, may be included to mate the upper and lower portions. The upper and lower portions may be fixedly or removable secured together. 
     Tonsillectomy Tip 
     The tonsils are located on either side of the throat and removed under general anesthesia. In this procedure, the unattached end of the tonsil is usually grasped with forceps while an incision is made at the other end to remove it from the throat. Thus, similar to adenoidectomy, access is also difficult and the surgical field cramped. The tonsillectomy tips described here are interchangeable tips specifically configured to address many of these difficulties with tonsillectomy. 
     The suction handle (handle with the elongate body attached) and connector are generally of the same configuration and made from the same materials as described for the adenoidectomy tips. The tonsillectomy tips may also be malleable and provide the same advantages as those previously described. Further, the housing, blade assembly, and active electrode are typically made with the same materials. However, their configuration will differ. 
     In one variation, as depicted in  FIG. 2A , the tonsillectomy tip has a housing  200  that is tapered. Blade assembly  202  is integrated within the housing  200 . An opening in the active electrode  204  defines an aspiration port  206  through which suction may be applied to a tissue surface, usually the tonsil bed, as explained above. A rim of active electrode results that has a rim thickness  205  from about 0.5 mm to about 3.0 mm. The rim is insulated except for a about a 5 mm to about a 20 mm portion running along the outer edge  209 . About a 2 mm to about a 15 mm exposed (uninsulated) portion may also run along the inner edge  207 . Upon application of an energizing electrical signal (waveform), pulsed or continuous, plasma may be formed along the inner  207  and/or outer  209  edges of the rim to cut or coagulate tissue. As previously mentioned, cutting precision is typically not a result of the degree of sharpness of the electrode edge, and is not the case here. However, in some variations, one or more sides of the active electrode may be sharpened to form about a 10° to 40° edge. 
     Although shown as a triangular shaped opening in  FIGS. 2A and 2B , the aspiration port  206  may take various other shapes. The triangular configuration of the aspiration port may optimize suction at the tip of the device without compromising the preciseness of tissue dissection. 
     The active electrode may have a length from about 0.1 cm to about 1.5 cm. In one variation, the active electrode has a length of about 0.4 cm. At its widest portion, the active electrode has a width from about 0.1 cm to about 1.0 cm. In some instances, the active electrode has a width of 0.4 cm. The active electrode may also be configured with an upward curve so that it approximately conforms to the curvature of the tonsil (e.g., the palatine tonsil). This upward angle of the active electrode may be of any degree. For example, the upward angle may be from about 5° to about 60°. In some variations, the upward angle is about 30°. 
     The relationship between the housing and blade assembly components of  FIG. 2A  is further detailed in  FIG. 2B . In  FIG. 2B , housing  200  is shown as being formed by an upper portion  208  and a lower portion  210 . A pin  212  extending inferiorly from the internal surface of the upper portion  208  is threaded through a hole  216  of the blade assembly  214  to integrate the blade assembly  214  within the housing  200 . An adhesive may further be used to secure the housing and blade assembly components to one another. 
     The housing in  FIGS. 2A-2B  is shown as tapered, but need not be. In this variation, upper portion  208  is longer than bottom portion  210 . The upper portion  208  will generally be from about 0.3 cm to about 3.0 in length. The bottom portion  210  will generally also be from about 0.3 cm to about 3.0 cm in length. The difference in length between the upper and lower portions results in complete coverage of the aspiration port  206  on the top of the active electrode  204  but only partial coverage of the aspiration port  206  on the bottom of the active electrode  204 . With this configuration, suction may be provided through the undersurface of the active electrode. The aspiration port  206  may be from about 0.03 cm to about 0.5 cm wide, and about 0.03 cm to about 1.0 cm in length. In one variation, the aspiration port is about 0.17 cm in width and about 0.5 cm in length. A connective piece  218  is also shown in  FIG. 2B  that allows the integrated housing and blade assembly to be attached to the tip lumen. 
     The tonsillectomy tips herein described may provide more precise cutting and coagulation because of the particular suction electrode design. Here not only does the aspiration port suction smoke and fluids from the operative field to improve visualization, but suction and coagulation is capable of being directly and immediately placed on the tonsil bed from which the tonsil tissue has been resected. This is the raw surface where hemostasis is needed most, not on the tonsil itself, which is removed from the body. The active electrode rim also provides a larger surface that could be swept across the tissue to more effectively control bleeding. 
     Furthermore, use of the tonsil devices described here may result in less thermal injury. As further detailed below in Example 1, the depth of thermal injury was found to be less when the instant tonsil devices were employed in comparison to Bovie needles (0.26 mm vs. 0.77 mm) on tonsil tissue. Thermal injury was decreased by 66% when cut settings were used and by 73% when coagulation settings were used. 
     The electrical signals (radio frequency in this case) for generating the plasma may be provided by generators and electrical circuits of the kind well known in the art, or by those described in pending co-owned application Ser. Nos. 11/982,734 and 12/136,683, which are incorporated by reference in their entirety. The electrical signals are conventionally applied to the electrode by a conductor(s) extending through the electrosurgical device and not shown here. As previously mentioned, the plasma is formed along the edge of the active electrode by application of the electrical signals to the electrode. To further decrease the heat accumulation and associated collateral tissue damage, low duty cycle waveforms may be used. As well known, duty-cycle refers to the proportion of time that the electrical energy is actually being applied. Low duty-cycle here typically refers to duty-cycles of less than 10% which may be, for instance, 1% or less, or 0.1% or less. In some cases the low duty-cycle refers to the pulse voltage regime that is applied to the active electrode. For instance, a pulsed low duty-cycle signal may include a plurality of pulse bursts that are separated by more than one millisecond (e.g., has a frequency of less than 1 KHz) where each burst is shorter than one millisecond. The burst of pulses may include pulses that are biphasic (e.g., of alternating polarity) and the pulses may have different peak voltages. Again, none of this is limiting. The low duty-cycle is intended to minimize the spread of thermal injury, including tissue charring or burning. However, in some instances the devices described here may employ continuous waveforms or duty cycles of greater than about 50% or greater than about 75%. 
     Cutting or coagulation is generally obtained by energizing the active electrode with a suitable electrical signal (typically of different frequency, duty-cycle, etc.) for each surgical function. For example, when cutting is desired, the applied signal is an RF (radio frequency) signal having a frequency in the range of 100 KHz to 10 MHz. This energy may be applied in the form of bursts of pulses. Each burst will typically have a duration in the range of 10 microseconds to 1.0 millisecond. The individual pulses in each burst typically each have a duration of 0.1 to 10 microseconds with an interval therebetween of 0.1 to 10 microseconds. The actual pulses are typically square waves and bi-phasic, that is alternating positive and negative amplitudes. Generally the interval between pulses must be shorter than a lifetime of the plasma vapor cavity in order to maintain the cavity and the plasma regime during each pulse burst. In one variation the bursts each are separated by a duration of at least one millisecond. Typically the time between the pulse bursts is sufficient so that the duty-cycle is relatively low as explained above. This minimizes the undesirable heating effects. Coagulation may be achieved in the same manner, but by increasing output power of the device. 
     The generator associated with the electrosurgical devices may also allow varying degrees of cutting and coagulation. For example, in addition to a default power setting when the device is turned on, other settings to which the device could be adjusted are provided. This would provide in some instances higher hemostasis when cutting. 
     The electrosurgical devices described here are intended for single use, and can be employed with tonsillectomy, adenoidectomy, or combined procedures. In use, the tonsils and/or adenoids are accessed and a pulsed electrical signal applied to the active electrode of the interchangeable tip to form a plasma. In some variations, the active electrode is a wire electrode. The tissue is then cut or coagulated with the plasma. Suction may or may not be used when cutting or coagulating. In some instances, suction is applied simultaneously with proximal movement (pulling) of the device to suction cut the tissue. In other instances, suction is applied through the active electrode, as described above. 
     The electrosurgical devices described here may also be useful in “dry field” surgical procedures where there is no electrically conductive fluid added to the surgical field to, for example, aid conduction of energy between the active and return electrodes and/or to provide a cooling effect to the electrodes. When a dry field approach is employed, energy is typically transmitted only by the portion(s) of the active electrode that contacts tissue. In this instance the energy can be selectively provided to the areas in which it is desired. The application of suction to the tissue may further remove body fluids that would be naturally present in the field to further facilitate tissue contact. 
     Contrastingly, in a wet field (e.g., when the active and/or return electrodes are immersed or submerged in an electrically conductive fluid provided from outside the body), all parts of the active electrode that are in contact with the electrically conductive fluid provide energy. As a result, more energy than required is generally transmitted to the tissue, and less precisely. 
     Moreover it has been found that a concave blade does not operate well in a wet field (conductive medium) because components of the blade&#39;s electric field directed in opposite directions cancel each other. This does not occur in a dry field since current (energy) only flows to the tissue from that part of the blade in direct contact with the tissue. Hence a dry field approach is advantageous here, so the use of aspiration as described here is beneficial to create the dry field. Further, the suction (aspiration) here directed from the center of the blade pulls the tissue into the aspiration port thereby further decreasing the width of the tissue touching the blade and rendering the field even drier, thereby further improving the accuracy of current flow and the electric field effects described above. 
     The interchangeable tip may be exchanged for another at any time during the procedure. Thus, it may be useful to provide the suction handle and interchangeable tips with blade assemblies in a kit. Given that the device is intended for single use, one or more suction handles could be packaged with one or more interchangeable tips with blade assemblies. The interchangeable tips could be of the same type, e.g., all adenoidectomy tips or all tonsillectomy tips, or a mixture of the two types. In other instances, the kits may include a plurality of interchangeable tips without the suction handle. The interchangeable tips and suction handles may also be individually packaged. 
     The kits will also generally contain instructions for use. The instructions may include directions on how to start, operate, and shut down the device, as well as directions on how to adjust power level settings. Steps for changing one interchangeable tip to another, e.g., an adenoidectomy tip for a tonsillectomy tip, may also be provided. 
     The invention described herein will be further understood by the following non-limiting example. 
     EXAMPLE 1 
     Comparative Data on Thermal Injury to Tonsil Tissue 
     Excised human palatine tonsils were subjected to a series of surgical incisions using conventional “Bovie” needle tips at settings of 30 W Cut and 30 W Coag. Additional incisions were made using the electrosurgical tonsillectomy devices described here (“Tonsil Blade”) on settings of Cut 5 (20 W power output) for cutting and Coag 6 (30 W power output) for coagulation. Histology samples were harvested immediately after incision and evaluated for residual thermal injury using microscopy. A comparison of the depth of thermal injury (mm) and percent reduction in thermal injury is provided in Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Comparison of Thermal Injury Depth in Tonsil Tissue 
               
            
           
           
               
               
               
            
               
                   
                 Thermal Injury 
                   
               
               
                   
                 Depth (mm) 
               
            
           
           
               
               
               
            
               
                   
                 Cut 
                 Coag 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Tonsil Blade 
                 0.26 
                 0.26 
               
               
                   
                 (20 W Cut) 
               
               
                   
                 (30 W Coag) 
               
               
                   
                 Bovie 
                 0.77 
                 0.96 
               
               
                   
                 (30 W Cut) 
               
               
                   
                 (30 W Coag) 
               
               
                   
                 Percent Reduction 
                 66% 
                 73% 
               
               
                   
                 p value 
                 p &lt; 0.05 
                 p &lt; 0.005 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 2 
     Comparative Data on Thermal Injury to Adenoid Tissue 
     Excised porcine adenoid tissue was subjected to a series of incisions using an electrosurgical device comprising the active electrode configuration shown in  FIGS. 1A-1G  at settings of Cut 9 (power output 40 W at 600 Ohms with 1930 Volts peak to peak maximum) for cutting and Coag 7 (power output 30 W at 1000 Ohms with 3960 Volts peak to peak maximum) for coagulation and Cut 10 (power output 50 W at 600 Ohms with 2110 Volts peak to peak maximum) for cutting and Coag 10 (power output 50 W at 1000 Ohms with 5000 Volts peak to peak maximum) for coagulation. Thermal injury from these incisions was compared to thermal injury resulting from an electrosurgical device using the wire electrode and housing design of FIGS.  3  and  4 A- 4 B at the same settings. Histology samples were harvested immediately after incision and evaluated for residual thermal injury using microscopy. A comparison of the depth of thermal injury (mm) is shown in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Comparison of Thermal Injury Depth in Adenoid Tissue 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Electrode of FIGS. 
                   
               
               
                   
                 Settings 
                 1A-1G 
                 Wire Electrode 
               
               
                   
                   
               
               
                   
                 Cut 9 
                 0.45 
                 0.32 
               
               
                   
                 Coag 7 
                 0.48 
                 0.31 
               
               
                   
                 Cut 10 
                 0.72 
                 0.26 
               
               
                   
                 Coag 10 
                 0.52 
                 0.32