An apparatus for electrosurgical insulation

Abstract

An apparatus for applying an insulating sleeve (114, figure 1) to an electrosurgical instrument (100, figure 1), comprising a casing 202 comprising a first support structure 210 for supporting an insu

Description

Field of the invention This invention relates to the insulation of an electrosurgical instrument, and in particular to a device for applying an insulating sleeve to an electrosurgical instrument. Background of the invention Electrosurgery is a type of surgery that uses a high frequency electrical current to generate heat that provides a means to cut, dissect, fulgurate, ablate or shrink organic tissue. It has been shown to provide advantages such as increased cutting precision and minimised blood loss over more mechanical forms of surgery. Instruments that are used for electrosurgery typically comprise one or more electrical (or drive) cables that extend through the body of the instrument and that provide electrical current to an end effector of the instrument. It is important that these instruments are well insulated, electrically, to prevent electrical current that is carried through their cables or instrument shaft from being passed onto the body of a patient during a surgical procedure. Such passing of electrical current would result in electrocution of the patient. It is known to provide an applicator tool that is able to apply an insulating sleeve to an electrosurgical instrument. However, existing applicator tools are limited in the degree of precision with which they are able to apply a sleeve to the required position on the instrument. A high degree of precision is required in the insertion of insulating sleeves in order to: (i) provide a low likelihood of the sleeve leaving a portion of the instrument exposed that may result in electrocution of a patient, and (ii) reduce the likelihood of the sleeve becoming damaged due to poor positioning which may result in exposure of the patient to the instrument. Summary of the invention According to a first aspect, there is provided an apparatus for applying an insulating sleeve to an electrosurgical instrument, the apparatus comprising: a casing comprising a first support structure for supporting an insulating sleeve; and an applicator configured to be moved between a first position in which it is contained within the casing and a second position in which it is external to the casing; wherein the applicator comprises a second support structure configured to engage a proximal end of the insulating sleeve such that the insulating sleeve is carried by the applicator as the applicator is moved from the first position to the second position. The casing may comprise a channel that extends along the longitudinal axis of the casing, and the first support structure is located within the channel. The channel may comprise a first portion and a second portion, wherein the first portion is narrower than the second portion. The proximal end of the first support structure may be located on a ledge that separates the first portion of the channel from the second portion of the channel. The ledge may comprise an orifice and the proximal end of the first support structure surrounds the orifice. The support structure may comprise a plurality of protrusions, each protrusion of the plurality of protrusions comprising: a length that extends away from the ledge along the longitudinal axis of the casing; and a ridge positioned partially along the length. The plurality of protrusions may comprise three protrusions, each protrusion having the same length. The protrusions of the support structure may be concentrically positioned around the orifice about the longitudinal axis of the casing. The protrusions may be configured to deflect outwardly from the orifice. The casing may comprise an outer surface with a compliant portion that is configured to be deflected inwards. The casing may comprise an opening at its distal end and one or more internal grooves extending proximally of the opening along the length of the casing, the one or more internal grooves being configured to engage the applicator when the applicator is in the first position. The second support structure of the applicator may form a rim, wherein the rim surrounds the first orifice when the applicator is in the first position. The applicator may comprise a pair of opposing lever arms and the rim is formed from a plurality of portions that are attached to and extend outwardly from the lever arms. The portions may be concentrically arranged around the longitudinal axis of the applicator. When the applicator is in the first position, each protrusion of the plurality of protrusions may be arranged between two portions of the plurality of portions around the longitudinal axis of the applicator. The lever arms of the applicator may be connected at a fulcrum such that, when the lever arms are pressed together on a first side of the fulcrum they are separated on a second side of the fulcrum that opposes the first side. The apparatus may further comprise a removeable guide, wherein the casing is configured to receive the guide. The removeable guide may comprise a first end, a second end and an elongate shaft extending between the first and second ends. The apparatus may be configured to apply an insulating sleeve to an electrosurgical instrument. The second end of the applicator may comprise an aperture for housing an end effector tip of the electrosurgical instrument. The apparatus may further comprise a sleeve removal feature located in the channel proximal to the first support structure, the sleeve removal feature surrounded by a removal channel for capturing the insulating sleeve. The sleeve removal feature may comprise a prong terminating in a tip, the tip shaped to push between the electrosurgical instrument and the insulating sleeve as the apparatus is pushed over the electrosurgical instrument causing the insulating sleeve to be removed from the electrosurgical instrument and captured in the removal channel. According to a second aspect, there is provided a method for applying an insulating sleeve to an electrosurgical instrument, the method comprising: applying the insulating sleeve to a first support structure of an apparatus, the apparatus comprising a casing with the support structure and an applicator configured to be moved between a first position in which it is contained within the casing and a second position in which it is external to the casing, the applicator comprising a second support structure, the applicator being in the first position when the insulating sleeve is applied to the first support structure; engaging the insulating sleeve with the second support structure; and moving the applicator from the first position to the second position such that the insulating sleeve is carried by the applicator. The method may further comprise deflecting the first support structure so that the internal width of the insulating sleeve is greater than the internal width of the second support structure. The deflection may be caused by the device to which the insulating sleeve is to be applied, and the device may be progressed by a guide. Brief description of the figures The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings: figure 1 illustrates an electrosurgical instrument comprising electrical insulation; figure 2 illustrates a first view of an apparatus for applying an insulating sleeve to an electrosurgical instrument; figure 3 illustrates a second view of an apparatus for applying an insulating sleeve to an electrosurgical instrument; figure 4 illustrates a detailed view of an applicator for use within the apparatus of figure 3; figure 5 illustrates the applicator of figure 4 in use; figures 6A to 6D illustrate a process for applying an insulating sleeve to an electrosurgical instrument using the apparatus of figures 2 to 5; figure 7 illustrates features of the apparatus used for removing an insulating sleeve from an electrosurgical instrument; and figures 8a and 8b illustrate a detailed view of features of the apparatus used for removing an insulating sleeve from an electrosurgical instrument. Detailed description An example of the arrangement of an electrosurgical instrument 100 is illustrated in figure 1. The instrument comprises an instrument interface (not shown), a shaft 102 and an end effector 104. The shaft 102 is coupled at its distal end to the end effector 104, and at its proximal end to the instrument interface. The instrument can be mounted on a surgical robot arm by means of the instrument interface engaging with a drive assembly interface of the surgical robot arm. The surgical robot arm mechanically drives the electrosurgical instrument 100 through the engagement of the drive assembly interface and the instrument interface. Power may be applied to the electrosurgical instrument at the instrument interface. The surgical robotic system may comprise a user interface allowing the electrosurgical instrument 100 to be electrically manipulated by an operator. For example, a surgeon's console may comprise hand controllers, a screen, and, optionally, foot pedals. A surgeon may operate an electrosurgical instrument by manipulating a hand controller, a touch screen, or a foot pedal. As an example, the surgeon may control the motion of the electrosurgical instrument by moving a hand controller, and the application of power to the electrosurgical instrument by operating a user input, such as a button, on the hand controller. The surgical robotic system may further comprise a number of different electrosurgical instruments, both electrosurgical and non-electrosurgical. The end effector 104 is configured for insertion into the body of the patient, to perform a method of surgery. In the example illustrated in figure 1, the end effector 104 comprises a pair of curved blades 104a, 104b that form a pair of forceps. The forceps can be used to cut the organic tissues of a patient during a surgical procedure. It will be appreciated that, whilst the end effector in figure 1 is illustrated as a pair of forceps, an alternative end effector could be used in its place. The end effector 104 is coupled to the shaft 102 by an articulation 106. The articulation 106 allows the forceps to rotate about the shaft 102 in at least one degree of freedom. During an electrosurgical procedure, power is supplied to the electrosurgical instrument 100, for example by the surgical robotic system. This power is supplied in the form of a high frequency, alternating electrical current. Current that is provided to the end effector 104 is passed through the shaft 102 of the electrosurgical instrument and the articulation 106. In known electrosurgical instruments, one or more drive cables located within the shaft are used to power the end effector. In contrast, for the arrangement illustrated in figure 1, the whole of the electrosurgical instrument 100, including the shaft 102, becomes live when current is provided to the end effector 104. The current heats the end effector 104 so that, when the end effector 104 is applied to organic tissue, the heated end effector 104 can coagulate and desiccate the tissue, which results in the occlusion of blood vessels and halting of bleeding. The end effector 104 may also be used to penetrate and dissect the tissue. As, for the transfer of current through the electrosurgical instrument 100, the whole of the instrument 100 becomes live, it is necessary for the shaft 102 and the articulation 106 to be electrically insulated so as not to cause unwanted burns to the patient, either via direct contact or capacitively. To provide initial protection, the shaft 102 comprises two layers of insulation along its length. The first layer of insulation is a powder coating 108. The powder coating 108 may be an Ethylene Tetrafluoroethylene (ETFE) powder coating. The powder coating 108 extends to cover all but the distal end 112 of the shaft. The second layer of insulation comprises a heat shrink 110. The heat shrink may be a MT-1000 heat-shrink. The heat shrink 110 ends at the distal end of the shaft, but proximally to the end of the powder coating 108. The powder coating and heat shrink insulation cannot be applied to the articulation 106 of the electrosurgical instrument 100, as this would limit the range of motion of the articulation. Furthermore, the distal end of the shaft 112 and the articulation 106 must be capable of being effectively cleaned and sterilised between surgical procedures. At the same time, it is important that the distal end of the end effector 104 remains exposed. Where the end effector is a pair of forceps, it is important that the blades 104a, 104b of the forceps are exposed and are able to perform their full range of motion. To provide electrical insulation to the distal end of the shaft 112 and the articulation 106 of the electrosurgical instrument 100, an insulating sleeve 114 is provided. The insulating sleeve comprises a first end 116, a second end 118 and at least one portion that extends between the first and the second ends. The first end 116 and the second end 118 each comprise an opening. The insulating sleeve 114 may be configured to stretch around the respective parts of the electrosurgical instrument that it is configured to cover. The insulating sleeve 114 may be cylindrical in shape. The insulating sleeve 114 may be formed of a material such as silicon, which is capable of resisting high temperatures that arise during electrosurgery. In addition to this, the material of the insulating sleeve 114 may be resistive to fatigue for the range of strains expected during end effector movement. The material of the insulating sleeve 114 may also be elastic, so that it is able to expand to surround the electrosurgical instrument 100. The inner surface of the insulating sleeve 114 is coated to ensure a smooth finish. The coating of the inner surface may be glutinous. This enables the surface of the electrosurgical instrument 100, which is polished, to stick to the inner surface of the insulating sleeve 114. Thus, high friction between the surface of the electrosurgical instrument 100 and the insulating sleeve 114 is ensured. When the insulating sleeve 114 is placed overthe electrosurgical instrument 100, the first end 116 of the sleeve interfaces with the distal end of the heat shrink 110 that insulates the shaft 102. The first end 116 of the sleeve is positioned over and interfaces with the powder coating 108. At least one portion of the insulating sleeve 114 overlies the distal part 112 of the shaft. The second end 118 of the insulating sleeve overlies a portion of the end effector 104. Where the end effector is a pair of forceps, second end 118 overlies a portion of the blades of the end effector 104. The first end 116 of the insulating sleeve does not necessarily have to directly abut the distal end of the heat shrink 110. However, to ensure that an operator of the electrosurgical instrument is protected from electrical shocks induced by the live system, it is important that the creepage and clearance distances between the proximal end of the insulating sleeve 114 and the live portions of the shaft 102 are maintained. The creepage distance is the shortest distance along the surface of a solid insulating material between two conductive parts. Clearance distance is the shortest distance in air between two conductive parts. To ensure that both the creepage and clearance distances are maintained, an appropriate positioning of the insulating sleeve 114 over the electrosurgical instrument 100 is essential. This is because it may be difficult to reposition the insulating sleeve 114 once it has been placed on the instrument 100. The insulating sleeve 114 can be positioned on the shaft 102 of the instrument manually. However, this process incurs considerable time and effort. Manual positioning of the sleeve 114 may also result in perforation of the sleeve with the tip of the end effector 104 or harm caused by the tip of the end effector if the sleeve is displaced. A sleeve applicator device has been provided to ensure the correct application of an insulating sleeve onto the shaft. An example of this apparatus 200 is illustrated in figures 2 and 3. The apparatus 200 comprises a casing 202 that is configured to house an internal mechanism. The casing 202 is small and ergonomically arranged so that it can fit within the hand of a user. In the example illustrated in figure 2, the casing 202 has a generally ovular shape. The casing 202 may be formed of a thermoelastic polymer, such as polypropylene. The casing 202 comprises a first end 204 and a second end 206. The casing 202 may further comprise a channel 208 that extends between the first end 204 and the second end 206. The channel 208 may extend along the longitudinal axis 220 of the casing 202. In other words, the length of the channel 208, may extend between the first end 204 and the second end 206 of the casing 202. The longitudinal axis of the channel 208 may be parallel to the longitudinal axis of the casing 202. The dimensions of the channel 208 may be such that it is configured to receive an electrosurgical instrument as illustrated in figure 1, for example. As illustrated in figure 1, the electrosurgical instrument 100 comprises an instrument interface (not shown), a shaft 102, a distal articulation 106 and an end effector 104 that is located distally of the distal articulation. The smallest diameter of the channel 208 must therefore be larger than the largest diameter of the electrosurgical instrument 100. The casing 202 further comprises a first support structure 210. First support structure 210 is located internally of the outer profile of the casing 202. The first support structure 210 surrounds the channel 208. The first support structure is configured to support an insulating sleeve as illustrated in figure 2, for example. The first support structure 210 is configured to mount the insulating sleeve 114 such that the sleeve surrounds the electrosurgical instrument 100 when the instrument is positioned within the channel 208. The arrangement of the casing 202 is such that, when an electrosurgical instrument 100 is advanced through the channel 208 from the first end 204 to the second end 206, the insulating sleeve is released onto the instrument by the first support structure 210. In figure 2, the insulating sleeve 114 is illustrated as mounted on the first support structure 210. As is visible from figure 3, the casing 202 may comprise a first part 236 and a second part 238. Preferably, the internal mechanisms of the two parts 236, 238 of the casing 202 are identical. The two parts 236, 238 may be pivotally coupled together. For example, the two parts 236, 238 may be coupled together by a hinge 246, about a pivot point located within the hinge. The hinge 246 has a hinge axis 248 about which the first part 236 and the second part 238 are able to rotate. By forming the casing 202 from two parts 236, 238, the casing 202 can be opened to enable the electrosurgical instrument 100 to be removed from the casing 202 once the insulating sleeve 114 has been applied from the casing 202 to the electrosurgical instrument by advancing the electrosurgical instrument through the closed casing 202. The channel 208 of the casing 202 is formed from recesses located in both the first and second parts 236, 238 of the casing 202. When these parts of the casing 202 are interconnected by virtue of the casing being closed, the channel 208 forms a closed passage located within the casing 202. The channel 208 further comprises a first portion 224 and a second portion 226. The first portion 224 of the channel 208 extends along the length of the casing 202 from its first end 204 along a central axis 220 of the casing 202. In figure 3, the axis 220 is illustrated as intersecting the channel 208 in the first part 236 of the casing 202. However, it will be appreciated that, when the casing 202 is closed, the axis 220 is located in the middle of the first part 236 and the second part 238 of the casing 202. The second portion 226 of the channel 208 extends in a direction opposing the direction of extension of the first portion 224 of the channel 208 along the length of the casing 202 from its second end 206. The first portion 224 and the second portion 226 of the channel 208 intersect at a ledge 228. The ledge 228 may be located within the channel 208 of the casing 202. The ledge 228 separates the first portion 224 of the channel from the second portion 226 of the channel. That is, the ledge is positioned between the first portion 224 of the channel and the second portion 226 of the channel and forms a barrier between at least part of the first and second portions. A first part of the ledge 228 may be located in the first part 236 of the casing 202, and a second part of the ledge 228 may be located in the second part 238 of the casing 202. The ledge 228 surrounds an opening or orifice 240 interconnecting the first portion 224 and the second portion 226 of the channel 208. The channel 208 may be circular in cross section, such that both the first portion 224 and the second portion 226 of the channel 208 form a cylinder. The first and second portions 224, 226 may alternatively have a cross section of any other geometric shape. The first and second portions 224, 226 of the channel 208 may have the same diameter. Alternatively, the second portion 226 of the channel 208 may have a diameter that is larger than the diameter of the first portion 224 of the channel 208. In other words, the first portion 224 of the channel 208 may be narrower than the second portion 226 of the channel 208. The second portion 226 of the channel 208 may be wider than the first portion 224 of the channel 208 in order to accommodate more components. This is because more components may be required to pass through the second portion 226 of the channel 208 than the first portion 224 of the channel 208. Specifically, an insulating sleeve may be housed, and applied to an electrosurgical instrument, within the second portion 226 of the channel 208. Additionally, the first support structure 210 of the casing 202 may be located within the second portion 226 of the channel 208. The additional space requirements for housing these components may result in the second portion 226 of the channel 208 being chosen to be wider than the first portion 224 of the channel 208. The first support structure 210 of the casing 202 is located on the ledge 228 that connects the first portion 224 and the second portion 226 of the channel 208. More precisely, the proximal end of the first support structure is located on and connected to the ledge 228. The proximal end of the first support structure may be defined as the end of the support structure that is closest to the first end 204 of the casing 202. The proximal end of the first support structure 210 may otherwise be referred to as the base of the first support structure. The first support structure 210 may be formed of a plurality of protrusions 230. The plurality of protrusions 230 may surround the opening 240 located on the ledge 228. More specifically, the proximal ends of the plurality of protrusions 230 may surround the opening 240 located on the ledge 228. That is, the proximal ends of the plurality of protrusions 230 may be positioned around the orifice 240. The proximal ends of the plurality of protrusions may be positioned uniformly around the orifice 240. Each protrusion of the plurality of protrusions may be concentrically positioned around the orifice 240 about the longitudinal axis of the casing 202. That is, each protrusion may be positioned in a circular arrangement around the orifice 240, with the longitudinal axis of the casing 202 in the centre of that circular arrangement. In the example illustrated in figure 3, each protrusion in the plurality of protrusions 230 extends along an axis that is parallel to the axis 220 of the channel 208. The plurality of protrusions 230 extends towards the second end 206 of the casing 202. Each protrusion of the plurality of protrusions has a length 232 in the direction of the axis 220. In some examples, each protrusion of the plurality of protrusions has the same length 232. This may be advantageous as it allows an insulating sleeve to be released from each protrusion of the plurality of protrusions at the same time as the remaining protrusions as the instrument is advanced through the sleeve applicator device, which allows for the even application of the insulating sleeve to the instrument. In other examples, one or more protrusions of the plurality of protrusions may have a different length as one or more other protrusions of the plurality of protrusions. The length of each protrusion of the plurality of protrusions extends away from the ledge 228 along the longitudinal axis 220 of the casing 202. The first length extends towards the second end 206 of the casing 202. Each protrusion of the plurality protrusions 230 of the first support structure 210 may be uniformly positioned around the orifice, or opening, 240. The orifice 240 may otherwise be referred to as a hole. The orifice 240 may pass entirely through the ledge 228. The orifice 240 may be circular in shape, as viewed from the first end 204 along the longitudinal axis 220 of the casing 202. In one example, the plurality of protrusions 230 may comprise three protrusions. In this example, two protrusions of the plurality of protrusions may be located on the first part 236 of the casing 202, and a third protrusion of the plurality of protrusions may be located on the second part 238 of the casing 202. Alternatively, two protrusions of the plurality of protrusions may be located on the second part 238 of the casing 202, and a third protrusion of the plurality of protrusions may be located on the first part 236 of the casing 202. A set of three protrusions has been identified by the inventors as being an appropriate number of protrusions for insertion into the casing 202, as this number is low enough to ensure ease of removal of the sleeve onto an electrosurgical instrument, whilst also high enough to ensure that the sleeve is supported within the casing 202 prior to its application. The protrusions of the plurality of protrusions 230 are structured so that, as they extend in a longitudinal direction away from the ledge 240 towards the second end 206 of the casing 202, they are angled inwards. Hence, the diameter that is formed by the distance between the tips of each protrusion of the plurality of protrusions 230 is smaller than the diameter of the orifice 240. The protrusions may be configured to deflect outwardly from the orifice. That is, the protrusions may be compliant so that they can extend outwards (transverse to the axis 220) when something is pushed through the inside of the plurality of protrusions. In other words, the protrusions may be configured to deflect outwardly from the orifice. The protrusions of the plurality of protrusions 230 may be constructed from a flexible plastic material to enable this compliance. Each protrusion 230 of the plurality of protrusions may further comprise a ridge 234. The ridge 234 may be positioned partially along the length 232 of each protrusion of the plurality of protrusions. That is, each ridge 234 may be positioned on its respective protrusion at a position along the length of the protrusion that is between the proximal and the distal end of the protrusion. The distal end of the protrusion is the end of the protrusion that is closest to the second end 206 of the casing 202. Each ridge 234 may be positioned on its respective protrusion so that it is closer to the proximal end of that protrusion than it is to the distal end of the protrusion. The proximal end of each protrusion is the end that is closest to the ledge 228. Each ridge is a narrow band of material that is raised out of the surface of its respective protrusion. Thus, each ridge 234 increases the outer diameter of the protrusion at the position along the length of the protrusion at which it is located. Each ridge 234 of each protrusion provides an increase in diameter of the protrusion at the location of the ridge over the diameter of the remaining proximal end of the protrusion. Each ridge may be located at the same position, along the length of its respective protrusion, as the position of the ridges on the remaining protrusions in the plurality of protrusions. Each ridge 234 of a respective protrusion 230 of the plurality of protrusions is configured to support a first end of an insulating sleeve that is to be applied to an electrosurgical instrument. Thus, the function of the plurality of protrusions 230, collectively, is to support an insulating sleeve within the casing 202 so that the sleeve is suited to be placed over the electrosurgical instrument. When the casing 202 is closed, the protrusions 230 are disposed in a circular arrangement around the orifice 240 on the ledge 228 of the casing 202. Thus, each ridge 234 of a respective protrusion provides a mounting surface on which the insulating sleeve 114 can be located. The casing 202 may be arranged so that it is ergonomically suited for use by an operator. As mentioned above, the overall size of the casing 202 is such that it fits within the hand of a user. The casing 202 may comprise a compliant portion 214 that is configured to be deflected inwards. The compliant portion 214 may be located on an outer surface of the casing 202. The compliant portion may be located on a first part 236 of the casing 202 and / or the second part 238 of the casing 202. The casing 202 may comprise one or more compliant portions 214. Preferably the casing 202 comprises two compliant portions, one on each of the first and second parts of the casing 202. The compliant portion 214 may be located externally of the first portion 224 of the channel 208. The compliant portion 214 may be configured to be pressed down by a user. The compliant portion may therefore be formed as a button, or a spring. The purpose of the compliant portion is to allow a user to grip the casing 202, and to move components through the casing 202 with ease. This provides purchase to aid the user in advancing the instrument through the applicator when applying the sleeve to the instrument. It also provides purchase to aid the user in pulling the instrument out of the sleeve applicator device so as to remove the sleeve after use. The casing 202 may be configured so that the first part 236 of the casing 202 can be removed from the second part 238 of the casing 202. In other words, the first part 236 of the casing 202 may be completely separable from the second part 238 of the casing 202. This means that, following the use of the casing 202 to apply an insulating sleeve, the casing 202 can be discarded so that the assembled electrosurgical instrument can be removed from the casing 202 with ease. The compliant portion 214 may assist with holding the first and second parts of the casing 202 together during use by allowing a user to apply a force that presses the two portions towards each other. The apparatus of figure 3 further comprises an applicator 216. The applicator 216 is illustrated in detail in figure 4. The applicator 216 is provided, together with the casing 202, to assist with the application of an insulating sleeve onto an electrosurgical instrument. More specifically, the applicator 216 is configured to ensure that the insulating sleeve is applied to the electrosurgical instrument at the correct position on the instrument. To enable this correct positioning, the applicator comprises a second support structure 244 (separate to the first support structure 210 of the casing 202) that is configured to engage a first end 116 of the insulating sleeve. The applicator 216 is configured, in use, to move between a first position in which it is contained within the casing 202 and a second position in which it is external to the casing 202. The applicator is, more specifically, configured to move from the first position to the second position along the longitudinal axis 220 of the casing 202. In figure 3 the applicator 216 is illustrated in the first position within the casing 202. The second position will be described in further detail below. The applicator 216 and the casing 202 may comprise complimentary features to enable the housing of the applicator 216 within the casing 202 in the first position. The applicator comprises its own longitudinal axis 302 that extends from a first end 304 of the applicator (which is housed towards the upper end 206 of the casing) to a second end 306 of the applicator (which is housed towards the lower end 204 of the casing). The applicator 216 is sized and shaped so that it is configured to fit within a human hand. This sizing and shaping allows the applicator 216 to be straightforwardly handled by a user when it is used to apply an insulating sleeve to an electrosurgical instrument. The second support structure 244 of the applicator may form a rim 326. The rim 326 has at least one upper surface 308. The at least one upper surface may face towards the second end 304 of the applicator. The at least one upper surface 308 may come into contact with an insulating sleeve during use of the applicator. More specifically, the at least one upper surface 308 may come into contact with the first end 116 of an insulating sleeve, such that the surface is engaged by the insulating sleeve. The rim 326 may be referred to as such due to its ringshaped structure. The rim 326 may be configured to surround the orifice 240 when the applicator is in the first position within the casing 202. More specifically, the rim 326 may be viewed as surrounding the orifice 240 when it is viewed along the longitudinal axis 220 of the casing 202. The rim 326 may comprise an outer circumference and an inner circumference, with a hole 318 positioned within the inner circumference. The rim 326 may be circular in shape. The innerdiameter of the rim 326 may be greater than the diameter of the orifice 240. The rim 326 may be discontinuous around its inner and / or outer circumference. That is, the rim 326 may be formed of two or more portions 310, 312, 314, 324 that are separated from each other around the circumference of the rim 326. In other words, there may be one or more gaps 316 in the rim 326 between adjacent portions of the rim 326. The portions may be positioned around the longitudinal axis of the casing. The rim 326 may be bifurcated. The ring may be trifurcated. That is, there may be three gaps around the circumference of the rim 326 that separate adjacent portions of the rim 326 from each other. The applicator 216 may also comprise two or more lever arms 320, 322. Preferably the applicator comprises two lever arms 320, 322, otherwise referred to as a pair of lever arms 320, 322. Where the applicator comprises a pair of lever arms 320, 322, the arms may oppose each other (i.e., sit on opposing sides of the applicator axis 302) The applicator may have any alternatively suitable number of arms. The rim 326 may be connected to the lever arms 320, 322. The lever arms 320, 322 may extend, in an unloaded state, in a direction that is parallel to the longitudinal axis 302 of the applicator. The lever arms 320, 322 may extend away from the second support structure 244 towards the second end of the applicator. The lever arms 320, 322 may also extend away from the second support structure towards the first end of the applicator. The rim 326 of the second support structure may be attached to the lever arms 320, 322. More specifically, each portion of the rim 326 may be attached to one of the lever arms 320, 322. That is, each portion of the rim 326 may be attached to and extend outwardly from a respective lever arm. In one example, where the rim 326 has three portions and two lever arms 320, 322, two portions may be attached to a first lever arm and a third portion may be attached to the second lever arm. In another example, the lever arm may have four portions and each lever arm may have two portions attached to it. Where the rim 326 has four portions, two of the four portions may be smaller in length than the remaining two portions. The two smaller portions may join together, when the applicator is in the first position, to form a portion of the ledge that is the same size as the other larger portions. The lever arms 320, 322 of the applicator may be connected together at a fulcrum. The fulcrum, by definition, forms a point about which the arms are able to rotate relative to each other. The fulcrum may be located at a point, such that the two lever arms 320, 322 are adjoining at the fulcrum. Alternatively, the fulcrum may be located on a bracket 328 that spans between the lever arms 320, 322. The bracket 328 may separate the lever arms 320, 322 from each other. The bracket 328 may be connected to each lever arm 320, 322 towards the first end 304 of the application. The lever arms 320, 322 may be pressed above the fulcrum in order to cause them to extend below the fulcrum. That is, a force may be applied to the lever arms 320, 322 to push them inwards towards the axis 302. Depressing the lever arms 320, 322 towards each other above the fulcrum causes the arms to expand away from each other below the fulcrum. The arms are moved away below the fulcrum to move the portions away from each other. The lever arms 320, 322 above the bracket 328 may have indents on them to aid manipulation by the fingers of a hand. The bracket 328 of the applicator may comprise a hole 310. The hole 310 may be sized so that a surgical instrument can pass through it. The hole 310 may enable a removeable guide (described below) to pass through the applicator. The inner diameter of the rim 326 may be smaller than that of an insulating sleeve when the insulating sleeve is applied to the instrument. This means that, when the applicator is in the first position and a surgical instrument is pushed through the applicator, the sleeve is attached to, or engaged with, the rim 326. Specifically, the first end 116 of the sleeve is attached to the rim 326. This means that the sleeve cannot retract proximally along the surgical instrument once the sleeve has been engaged with the applicator. In other words the rim 326 ensures that, in the second position, the insulating sleeve is applied to the electrosurgical instrument at the correct distance along the instrument. The correct distance may be different for different surgical instruments, but generally is a position that ensures that the sleeve covers the distal articulation 106 of the instrument. This positioning ensures that electrically live components of the instrument do not come into contact with the patient during electrosurgery. Where the lever arms 320, 322 extend below the rim 326, towards the second end 306 of the applicator, the arms are provided to interact with the casing 202 when the applicator is in the first position. The ratio of the length of the lever arms 320, 322 below the rim 326, verses above the rim 326, may be between 1:5 and 1:2. The ratio of the length of the lever arms 320, 322 below the rim 326, verses above the rim 326, may be more specifically between 1:3 and 1:4. Each lever arm 320, 322, below the rim 326, is configured to fit within a corresponding opening (not illustrated) located on the ledge 228 around the orifice 240 of the casing 202 when the applicator is in the first position. The openings may be positioned around the longitudinal axis 220 of the casing 202. The openings may extend entirely through the ledge of the casing 202. Each opening may have a width and depth (as observed perpendicularly to the longitudinal axis 220 of the casing 202) that is the same as, or wider than, the corresponding dimensions of the lever arms 320, 322 of the applicator. When the applicator is in the first position, each lever arm of the applicator fits within a respective opening in the casing 202. Thus, the interaction between the small openings and the lever arms 320, 322 provides a mechanism that enables the applicator to be securely housed within the casing 202 when the applicator is in the first position. In the first position, the second support structure 244 of the applicator is configured to interact with, or compliment, the first support structure 210 of the casing 202. More specifically, when the applicator is in the first position, the rim 326 may interact with the protrusions 230 of the casing 202. More specifically, each gap 316 between two adjacent portions of the rim 326 may be filled by a protrusion 230 of the plurality of protrusions. In the first position, the at least one upper surface 308 of the rim 326 of the applicator may be positioned at the same location along the longitudinal axis 220 of the casing 202 as the ridges of the protrusions. This means that, together with the ridges on the protrusion, the rim 326 of the applicator forms a solid ring on which an insulating sleeve may rest when the applicator is in the first position. The number of portions of the rim 326 may be the same as the number of protrusions 230 in the casing 202. In an example, where the casing 202 comprises three protrusions 230, the rim 326 may be formed of three portions. Having the same number of portions and protrusions means that the portions can be evenly located between the protrusions. The second end 206 of the casing 202 may comprise an opening. The opening may be wider than the width of the applicator, where the width of the applicator extends perpendicularly to the longitudinal axis of the casing. The walls of the second portion of the channel may comprise one or more grooves 212. The opening in the second end of the casing and the grooves 212 in the channel are configured to enable the location of the applicator within the casing when the applicator is in the first position. The grooves 212 allow the applicator to be slid towards the second end of the casing, and out of the casing, in order to move the applicator from the first to the second position. Note that the grooves 212 may also be used to move the applicator from the second to the first position. The applicator may be made of a compliant material such that, when it is in the first position, the inner diameter of its rim 326 is smaller than it is when it is in the second position. This compliance allows the applicator to be compactly housed within the casing in the first position, but also allows the rim 326 to be widened so that a surgical instrument can be removed from the applicator after an insulating sleeve has been applied to that instrument. The apparatus 200 may further comprise a removable guide 222 which is used to guide the electrosurgical instrument 100 through the casing 202. The casing 202 may be configured to receive the guide. In other words, the casing may comprise a recess within which the guide may be housed. The removeable guide comprises a first end 402, a second end 406 and an elongate shaft 408 that extends between the first and second ends. The second end 406 of the removable guide 222 forms a tip that leads the removable guide 222 (and thereby the electrosurgical instrument) through the casing 202. The first end 402 of the removable guide 222 may comprise two diverging branches 412, 414. Each of the two branches 412, 414 is preferably formed from a rigid plastic, and comprises a proximal end that is connected to the shaft 408. The two branches 412, 414 may be configured to separate from each other at their distal ends. The separation of the branches provides an opening 416 between the branches at the first end 402 of the removable guide 222. The opening 416 is configured to be interfaced by the end effector of an electrosurgical instrument. For example, where the end effector is a pair of forceps, the opening 416 is configured to interface with and house the tips of the blades of the forceps when they are closed. When the end effector interfaces with the opening 416, the longitudinal axis of the shaft 102 of the electrosurgical instrument 100 may be aligned with the longitudinal axis of the shaft 408 of the removable guide 222. Thus, when the removable guide 222 is placed within the casing 202 of the device and the end effector 104 is engaged with the opening 416, the removable guide 222 enables the electrosurgical instrument 100 to be guided though the casing 202 in alignment with the applicator. The electrosurgical instrument 100 can therefore be guided accurately through the casing 202. The diameter of the shaft 408 of the removable guide 222 is smaller than the diameter of the shaft 102 of the electrosurgical instrument 100. The diameter of the shaft 408 of the removable guide 222 is similar to the diameter that is formed by the distance between the tips of each protrusion of the plurality of protrusions 230. The shaft 408 is configured to pass through both the first portion and second portions of the channel 208 of casing 202 without interfering with the orifice 240 or the first support structure 210. The diameter of the shaft 408 of the removable guide 222 is also smaller than the diameter that is formed by the distance between the tips of each protrusion of the plurality protrusions 230. Thus, the shaft 408 of the applicator can be progressed through the casing 202 without altering the positioning of the protrusions. The removable guide 222 further comprises a limiting ring 510. The limiting ring 510 prevents the insulating sleeve from sliding off the second end 406 of the shaft once it has been positioned on the shaft 408. To position the insulating sleeve 114 on the removable guide 222, the first end 116 of the sleeve may slide onto the second end 406 of the applicator and may be pulled down the shaft 408 over the limiting ring 510. As the sleeve is made of a compliant material, it may extend and stretch over the limiting ring 510 as it is pulled down the shaft. Once the insulating sleeve has been pulled down over the limiting ring it may be retracted so that it can only be pushed back up to the second end 406 of the applicator until its second end abuts the limiting ring. Thus, the second end of the insulating sleeve abuts the limiting ring when the sleeve is positioned within the casing 202. Thus, the limiting ring 510 prevents the sleeve from being displaced off the removable guide 222, for example during storage due to temperature or time dependent deformations in the sleeve. Figures 6A-6D illustrate the method of applying an insulating sleeve 114 to an electrosurgical instrument 100 using the apparatus illustrated in figures 2-5. At the start of this method, as illustrated in figure 6A, the casing 202 is in a closed configuration. That is, the first and second parts of the casing 202 are interfaced together. The applicator 216 is in the first position, within the casing 202. The insulating sleeve 114 is first arranged so that it is mounted on both the first and second support structures. More specifically, the insulating sleeve 114 is mounted on the ridges 234 of the plurality of protrusions 230 and on the rim 326 of the applicator, such that the first end 116 of the insulating sleeve 114 interfaces with these ridges. The removable guide 222 may also be located within the casing 202 at the step of the method illustrated in figure 6A. The removable guide 222 may interface with the insulating sleeve such that the distal end of the insulating sleeve interfaces with the limiting ring 510 of the removable guide 222. At step 6A, the insulating sleeve is applied to the support structure of the apparatus. As described above, the apparatus comprises a casing with the support structure and an applicator configured to be moved between a first position in which it is contained within the casing and a second position in which it is external to the casing. More specifically, the insulating sleeve is applied to the first support structure 210 (i.e., the plurality of protrusions) of the apparatus. The applicator is in the first position when the insulating sleeve is applied to the first support structure. Also at step 6A, the distal end of the electrosurgical instrument 100 is introduced into the casing 202. More specifically the electrosurgical instrument is introduced to the first end 204 of the casing 202. The insulating sleeve is positioned on both the rim 326 of the applicator and the protrusions 230 of the casing , within the casing 202. That is, the applicator is in the first position within the casing 202. The distal end of the electrosurgical instrument 100 may be introduced into the casing 202 via the removable guide 222. In this example, the end effector 104 of the electrosurgical instrument 100 may be introduced into the opening of the removable guide 222. Where the end effector 104 is a pair of forceps, the closed blades 104a, 104b of the forceps may be inserted into the aperture 416. When the end effector 104 is engaged with the aperture 416, the longitudinal axis of the shaft 102 of the surgical instrument 100 is aligned with the longitudinal axis of the removable guide 222. At step 6B, the surgical instrument is progressed through the casing 202 by pushing it along the longitudinal axis 220 of the casing towards the second end of the casing 202. The applicator moves with the instrument along the longitudinal axis of the casing. At the same time, the compliant portions of the casing 202 may be held down to force the first and second parts of the casing 202 together. The insulating sleeve will remain stationary on the applicator and the protrusions 230 of the casing 202 until the instrument is pushed through the orifice 240 of the casing. At this point, as the shaft 102 of the electrosurgical instrument is significantly wider than the distance between the distal end of the protrusions of the first support structure 210, the shaft 102 engages with and pushes the plurality of protrusions outward as it is progressed through the orifice. This, in turn, expands the inner diameter of the insulating sleeve that is positioned on the first support structure 210. This expansion in the inner diameter of the insulating sleeve results in an increase in friction that pushes the sleeve upwards towards the second end 206 of the casing 202. The diameter that is formed by the distance between the tips of each protrusion 230 of the plurality of protrusions is smaller than the diameter of the orifice 240. Thus, as the electrosurgical instrument 100 and the removable guide 222 continue to advance through the casing 202, the insulating sleeve 114 is pushed off the ridges 234 of the plurality of protrusions 230 and onto the shaft of the electrosurgical instrument 100 through the engagement of the first support structure 210 with the shaft 102. At step 6C, the insulating sleeve 114 is advanced such that it is removed from the tips of the plurality of protrusions 230. At this point, the insulating sleeve is fully engaged with the second support structure 244 of the applicator, as it is no longer supported by the protrusions 230. The insulating sleeve is engaged with the applicator, via the at least one upper surface of the applicator which supports the sleeve as described above. Thus, the applicator, the instrument and the sleeve are moved together from the first to the second end of the casing. The applicator is therefore moved between its first and second positions. The applicator is moved upwardly with the sleeve. The sleeve 116 is therefore fully applied to the electrosurgical instrument 100. The diameter of the sleeve 116 has reduced from the diameter of the second support structure over which the sleeve 116 was stretched. When wrapped around the instrument shaft, the sleeve 116 has a larger diameter than its diameter at rest. Thus, the sleeve 116 envelopes the instrument shaft in a tight fit. The first end of the sleeve 116 is removed from the protrusions. However, the first end of the sleeve 116 remains on the rim 326 of the applicator. Thus, the sleeve is adhered to the instrument at an appropriate location on the instrument via the location of the sleeve on the rim 326. Once the insulating sleeve 114 has been applied to the electrosurgical instrument 100, then at step 6D both the casing 202 and the applicator 216 may be removed from the instrument. The casing 202 may be removed from the instrument by releasing the compliant portions of the casing 202, which removes the force that biases the two portions together. The two portions of the casing 202 may then be separately removed and discarded. The applicator may be removed by pressing down on the two distal portions of the lever arms 320, 322, which causes the arms to pivot apart from each other about the fulcrum as illustrated by the arrows in figure 6D. In figure 6D the applicator is in the second position, in which it is external to the casing. Pivoting the arms away from each other widens the radius of the rim 326 or, in other words, separates the portions of the rim 326 from each other. This means that the rim 326 is cleared of the first end of the insulating sleeve, and enables the applicator to be moved upwardly and away from the surgical instrument. The applicator can then be discarded. Where the apparatus comprises a removable guide 222, the guide may be removed with the applicator. The sleeve applicator device may also be used to remove the sleeve from the electrosurgical instrument 100. Figure 7 illustrates the features of the casing which aid this. Specifically, the casing 202 comprises a sleeve removal feature located in the channel 208 between the first support structure 210 and the first end 204 of the casing. The sleeve removal feature has two parts, one in one portion of the casing, the other in the other portion of the casing. These two parts may be identical. Each sleeve removal feature comprises a prong 701a,701b which is part-cylindrical in shape which extends from a proximal end midway between the first end 204 of the casing and the first support structure 210 and terminates at a distal end in a tip 702a,702b. The tip 702a,702b is part-conical in shape. The base of the part-cone meets the distal end of the prong 701a,701b. The top of the part-cone lies short of the first support structure 210. As is more easily seen in figure 8a, the tip 702a,702b may comprise two part-conical sections 801, 802. The first part-conical section 801 extends between the distal end of the prong 701a,701b and the base of the second part-conical section 802. The second part-conical section 802 extends between the top of the first part-conical section 801 and the top of the part-cone. The walls of the second part-conical section 802 are angled towards the longitudinal axis of the casing 220 at a steeper angle than the walls of the first part-conical section 801. When the two portions of the casing are closed together, the prongs 701a,701b and tips 702a,702b meet to form the whole sleeve removal feature having a cylindrical profile terminating in a tip having a conical profile and ending proximal to the first support structure 210. Although the whole sleeve removal feature is cylindrical in profile when the two portions of the casing are brought together, the prongs 701a,701b do not touch to form a solid cylinder. Instead, there remains a gap between the prongs 701a,701b. Similarly, although the tip has a conical profile when the two portions of the casing are brought together, the tips 702a,702b do not touch to form a solid cone. Instead, there remains a gap between the tips 702a,702b. Suitably, the longitudinal axis of the whole sleeve removal feature is coincident with the longitudinal axis 220 of the casing. Surrounding the sleeve removal feature (other than at its base) is a slot or gap 703a,703b. This gap forms a channel around the sleeve removal feature. This gap is at least as wide as the sleeve to be removed from the electrosurgical apparatus. The method to remove the sleeve from the electrosurgical instrument will now be described. For the purposes of this explanation, the proximal end of the sleeve is that furthest away from the end effector element when the sleeve is on the instrument. The distal end of the sleeve is that closest to the end effector element when the sleeve is on the instrument. Firstly, the two portions of the casing are closed around the shaft of the electrosurgical instrument such that: (i) the tip 702a,702b of the sleeve removal feature is located just below the proximal end of the sleeve of the instrument, and (ii) the tip 702a,702b of the sleeve removal feature is pointing towards the end effector of the instrument. Next, the user applies pressure to the compliant portion 214 of both case portions causing the compliant portions to bend against the instrument shaft. Then the user slides the sleeve applicator device towards the end effector whilst maintaining pressure against the compliant portions 214. This movement causes the sleeve, along with the sleeve applicator device, to slide off the distal end of the instrument over the end effector. As the user performs this movement, the tip 802 pushes up on the proximal edge of the sleeve and / or catches between the sleeve and the shaft of the instrument thereby causing the sleeve to push off the instrument. The sleeve removal feature pushes up through the sleeve causing the sleeve to be captured in the channel around the sleeve removal feature. The tip 802 may instead catch on the outer surface of the sleeve causing the sleeve to push off the instrument by friction. An advantage of the apparatus described above is that it allows the simple and accurate application of an insulating sleeve to an electrosurgical instrument. With many other apparatuses that perform such a function, the manual adjustment of the location of an insulating sleeve may be required after the sleeve is applied, to ensure that the correct location has been reached. In contrast, the use of the applicator to provide a rim 326 on which the insulating sleeve can be located even after the sleeve has been applied to the instrument ensures that the sleeve is not displaced during the assembly process (i.e., during removal of the instrument from the casing 202). The applicant hereby discloses in isolation each individual feature described herein and any 5 combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present 10 invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

1. An apparatus for applying an insulating sleeve to an electrosurgical instrument comprising an end effector coupled to a shaft by an articulation, the apparatus comprising:5 a casing comprising a first support structure for supporting an insulating sleeve; andan applicator configured to be moved between a first position in which it is contained within the casing and a second position in which it is external to the casing;wherein the applicator comprises a second support structure configured to engage a proximal end of the insulating sleeve, the proximal end of the insulating sleeve being the end10 that is furthest away from the end effector of the electrosurgical instrument when the insulating sleeve is on the electrosurgical instrument, such that the insulating sleeve is carried by the applicator as the applicator is moved from the first position to the second position.

2. The apparatus of claim 1, wherein the casing comprises a channel that extends along15 the longitudinal axis of the casing, and the first support structure is located within the channel.

3. The apparatus of claim 2, wherein the channel comprises a first portion and a second portion, wherein the first portion is narrower than the second portion.

204. The apparatus of claim 3, wherein the proximal end of the first support structure is located on a ledge that separates the first portion of the channel from the second portion of the channel.25 5. The apparatus of claim 4, wherein the ledge comprises an orifice and the proximal endof the first support structure surrounds the orifice.

6. The apparatus of claim 5, wherein the support structure comprises a plurality of protrusions, each protrusion of the plurality of protrusions comprising:a length that extends away from the ledge along the longitudinal axis of the casing;11 04 25anda ridge positioned partially along the length.5 7. The apparatus of claim 6, wherein the plurality of protrusions comprises threeprotrusions, each protrusion having the same length.

8. The apparatus of claim 6 or claim 7, wherein the protrusions of the support structure are concentrically positioned around the orifice about the longitudinal axis of the casing.

109. The apparatus of any of claims 6 to 8, wherein the protrusions are configured to deflect outwardly from the orifice.

10. The apparatus of any preceding claim, wherein the casing comprises an outer surface 15 with a compliant portion that is configured to be deflected inwards.

11. The apparatus of any preceding claim, wherein the casing comprises an opening at its distal end and one or more internal grooves extending proximally of the opening along the length of the casing, the one or more internal grooves being configured to engage the 20 applicator when the applicator is in the first position.

12. The apparatus of any preceding claim, wherein the second support structure of the applicator forms a rim, and wherein the rim surrounds the first orifice when the applicator is in the first position.2513. The apparatus of claim 12, wherein the applicator comprises a pair of opposing lever arms and the rim is formed from a plurality of portions that are attached to and extend outwardly from the lever arms.

14. The apparatus of claim 13, wherein the portions are concentrically arranged around11 04 25the longitudinal axis of the applicator.

15. The apparatus of claim 13 or 14, wherein there are gaps in the rim between adjacent 5 portions.

16. The apparatus of any of claims 12 to 15 when dependent on claim 6, wherein together with the ridges on the protrusions, the rim forms a solid ring on which the insulating sleeve can rest when the applicator is in the first position.

017. The apparatus of any of claims 13 to 16 when dependent on claim 6, wherein when the applicator is in the first position, each protrusion of the plurality of protrusions is arranged between two portions of the plurality of portions around the longitudinal axis of the applicator.

518. The apparatus of claim 13, wherein the lever arms of the applicator are connected at a fulcrum such that, when the lever arms are pressed together on a first side of the fulcrum they are separated on a second side of the fulcrum that opposes the first side.20 19. The apparatus of any preceding claim, further comprising a removeable guide,wherein the casing is configured to receive the guide.

20. The apparatus of claim 19, wherein the removeable guide comprises a first end, a second end and an elongate shaft extending between the first and second ends.2521. The apparatus of any preceding claim, wherein the apparatus is configured to apply an insulating sleeve to an electrosurgical instrument.11 04 2522. The apparatus of claim 21 when dependent on claim 20, wherein the second end of the applicator comprises an aperture for housing an end effector tip of the electrosurgical instrument.5 23. The apparatus of any of claims 2 to 22, further comprising a sleeve removal featurelocated in the channel proximal to the first support structure, the sleeve removal feature surrounded by a removal channel for capturing the insulating sleeve.

24. The apparatus of claim 23, wherein the sleeve removal feature comprises a prong 10 terminating in a tip, the tip shaped to push between the electrosurgical instrument and the insulating sleeve as the apparatus is pushed over the electrosurgical instrument causing the insulating sleeve to be removed from the electrosurgical instrument and captured in the removal channel.15 25. A method for applying an insulating sleeve to an electrosurgical instrument comprisingan end effector connected to a shaft by a distal articulation, the method comprising:applying the insulating sleeve to a first support structure of an apparatus, the apparatus comprising a casing with the first support structure and an applicator configured to be moved between a first position in which it is contained within the casing and a second 20 position in which it is external to the casing, the applicator comprising a second support structure, the applicator being in the first position when the insulating sleeve is applied to the first support structure;introducing the end effector of the electrosurgical instrument into a first end of the casing and progressing the electrosurgical instrument through the casing towards a second 25 end of the casing;engaging the insulating sleeve with the second support structure by a surface of the second support structure coming into contact with a proximal end of the insulation sleeve, the proximal end of the insulating sleeve being the end that is furthest away from the end effector of the electrosurgical instrument when the insulating sleeve is on the instrument; 30 andmoving the applicator from the first position to the second position such that the insulating sleeve is carried by the applicator to apply the insulating sleeve to the electrosurgical instrument.5 26. The method of claim 25, further comprising deflecting the first support structure sothat the internal width of the insulating sleeve is greater than the internal width of the second support structure.

27. The method of claim 26, wherein the deflection is caused by the device to which the 10 insulating sleeve is to be applied, and the device is progressed by a guide.

28. The method of any of claims 25 to 27, wherein in the first position, the insulating sleeve is attached to a rim of the second support structure, the inner diameter of the rim being smaller than the diameter of the insulating sleeve when the insulating sleeve is applied 15 to the instrument, thereby preventing the insulating sleeve from retracting along the surgical instrument once the insulating sleeve is engaged with the second support structure.11 04 25

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