WO2018100345A1

WO2018100345A1 - Electrode shield

Info

Publication number: WO2018100345A1
Application number: PCT/GB2017/053562
Authority: WO
Inventors: Aardash MISHRA; Jason Brewer; Dominic GRIFFITHS
Original assignee: Alesi Surgical Ltd
Current assignee: Alesi Surgical Ltd
Priority date: 2016-12-02
Filing date: 2017-11-27
Publication date: 2018-06-07
Anticipated expiration: 2019-06-02
Also published as: GB2557261A; GB201620481D0

Abstract

An electrode shield is disclosed. The shield comprises an elongate conduit having a passageway for receiving an electrode, which extends between an entrance aperture disposed at a proximal end of the conduit and an exit aperture disposed at a distal end of the conduit. The electrode shield further comprises a shroud disposed at a distal end of the conduit for receiving a distal portion of an electrode, the shroud comprising a base and a side wall which extends from the base and which terminates at an open, distal end of the shroud to form an enclosure. The base comprises an opening formed therein which is aligned with the exit aperture of the passageway, such that the electrode can pass from the conduit into the shroud. The passageway comprises a cross-sectional area which is less than a cross-sectional area of the enclosure, such that the shroud maintains a minimum separation of the distal portion of the electrode from electrically conducting surfaces.

Description

ELECTRODE SHIELD

The present invention relates to an electrode shield.

During intracorporeal surgery a working environment is created by introducing an insufflation gas, such as carbon dioxide, at the surgical site, which effectively inflates the local environment. Target tissues can be conveniently dissected and coagulated using energised instrumentation, such as laser, ultrasonic or electro-surgical accessories. An unwanted side effect of such powered instruments is the production of surgical smoke. During intracorporeal "minimally invasive procedures" this side effect is exacerbated owing to the closed environment, since the surgical smoke can rapidly build up and obscure the surgical site from the surgeon's view. The poor view can be hazardous to the patient when surgical procedures are being performed and as such it is desirable to remove the surgical smoke and to improve the surgeons' visibility.

A method of removing the smoke is to apply a vacuum tube that removes the smoke particles from the localised region to an external collecting device. Alternatively, it is possible to remove smoke particles suspended in local atmosphere using ionised particles, as described in the Applicants own international patent application WO201 1/010148. The ionised particles are created by creating a potential difference between the patient and an electrode located within the intracorporeal cavity. The ions generated from the electrode attach to the smoke particles and become attracted to the tissue of the patient. However, in order to create ionised particles, the electrode is required to maintain a minimum electrical potential relative to the patient and in situations where (electrically conducting) surgical devices for example, pass close to the electrode, the potential difference can fall dramatically. Also, the surgeon must avoid direct contact of the surgical instruments with the electrode in order to avoid an electrostatic discharge. We have now devised an electrode shield which addresses the above-mentioned problem. In accordance with the present invention, there is provided an electrode shield comprising an elongate conduit having a passageway for receiving an electrode, the passageway extending between an entrance aperture disposed at a proximal end of the conduit and an exit aperture disposed at a distal end of the conduit,

the electrode shield further comprising a shroud disposed at a distal end of the conduit for receiving a distal portion of the electrode, the shroud comprising a base and a side wall which extends from the base and which terminates at an open, distal end of the shroud to form an enclosure, the base comprising an opening formed therein which is aligned with the exit aperture of the passageway, such that the electrode can pass from the conduit into the shroud,

wherein the passageway comprises a cross-sectional area which is less than a cross-sectional area of the enclosure.

In an embodiment, the opening is disposed substantially centrally of the base. The conduit and shroud separately comprise a longitudinal axis which are substantially collinear. In an embodiment, a cross-sectional area of the passageway reduces along the length thereof, from the entrance to the exit aperture. The passageway thus comprises a taper so that radial movement of an electrode positioned therein becomes further restricted toward the exit aperture. Preferably, the exit aperture comprises a cross-sectional shape and area which substantially matches the cross-sectional shape and area of the opening. In an embodiment, the shroud and conduit comprise a substantially circular cross- sectional shape and the side wall of the shroud extends along a radius, around the opening.

In an embodiment, at least an internal surface of the side wall forming the shroud diverges with respect to a longitudinal axis of the shroud, in a direction which is along the longitudinal axis, away from the base. The internal surface of side wall preferably extends at an angle of at least 1 ° with respect to the longitudinal axis of the shroud, and more preferably 1 °-3°. The splay of the side walls provides for the electric field generated by the distal portion of the electrode to spread out from the distal portion, via the open end thereof, through a larger angular range than the situation where the side wall extends substantially parallel to the longitudinal axis of the enclosure, for example.

In an embodiment, the opening is separated from the side walls by at least 3mm, and preferably 3-5mm. This separation defines a minimum separation of an electrode, when positioned within the shroud, from conducting surfaces and bodies which would otherwise act to reduce an electrical potential between the electrode and bodily tissue.

In an embodiment, the shroud comprises a plurality of windows or holes disposed in the side wall thereof. The windows are angularly separated around the shroud and may comprise a square, rectangular or circular shape, for example. The windows may be disposed closer toward the distal end of the side wall than the base of the shroud.

In an embodiment, the side wall comprises a plurality of serrations or castellations formed at the distal end thereof.

In an embodiment, a proximal end of the conduit comprises means for detachably coupling the shield with medical devices. For example, the means for detachable coupling may comprise an external thread such as the Luer-Lok ® or an internal taper formed in the passageway at the entrance aperture, such as the Luer-Slip ®.

In an embodiment, the conduit and shroud at formed of a hydrophobic material.

In an embodiment, the electrode shield is formed of an electrically insulating material, such as silicone, fluoroethylene copolymer or polytetrafluoroethylene (PTFE).

Whilst the invention has been described above, it extends to any inventive combination of features set out above or in the following description. Although illustrative embodiments of the invention are described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to these precise embodiments. Furthermore, it is contemplated that a particular feature described either individually or as part of an embodiment can be combined with other individually described features, or parts of other embodiments, even if the other features and embodiments make no mention of the particular feature. Thus, the invention extends to such specific combinations not already described.

The invention may be performed in various ways, and, by way of example only, embodiments thereof will now be described, reference being made to the accompanying drawings in which:

Figure 1 is a perspective view of an electrode shield according to a first embodiment of the present invention;

Figure 2a is a longitudinal sectional view through the electrode shield illustrated in figure 1 ;

Figure 2b is an enlarged view from the distal end of the shroud illustrated in figure 1 ;

Figure 3 is a perspective view of an electrode shield according to a second embodiment of the present invention;

Figure 4a is a longitudinal sectional view through the electrode shield illustrated in figure 3;

Figure 4b is an enlarged view from the distal end of the shroud illustrated in figure 3;

Figure 5 is a perspective view of an electrode shield according to a third embodiment of the present invention;

Figure 6a is a longitudinal sectional view through the electrode shield illustrated in figure 5; and,

Figure 6b is an enlarged view from the distal end of the shroud illustrated in figure 5. Referring to figure 1 of the drawings, there is illustrated a perspective view of an electrode shield 100 according to a first embodiment of the present invention. The shield 100 is designed to preserve an electrical potential difference between an electrode (not shown), which in the simplest configuration may comprise a wire, positioned within the shield 100 and electrically conducting bodies and surfaces (not shown), such as those associated with medical instruments, located proximate to the electrode, so that a suitable potential difference is maintained to generate ions in the environment local to the electrode.

The shield 100 comprises a conduit 1 10, which may be formed of a hydrophobic, electrically insulating material such as silicone, fluoroethylene copolymer or polytetrafluoroethylene, for receiving the electrode. The conduit 1 10 comprises a substantially cylindrical shape having a passageway 1 1 1 which extends along the length thereof, between a proximal and distal end of the conduit. In an embodiment, the conduit 1 10 may be rigid and comprise a substantially linear shape, however, the skilled reader will recognise that the conduit 1 10 may alternatively comprise at least a flexible portion, so that it can be manipulated to conform to a particular profile.

The shield further comprises a shroud 120 disposed at a distal end of the conduit 1 10 which is arranged to receive a distal portion (not shown) of an electrode from the conduit 1 10. The shroud 120 may be formed integrally with the conduit 1 10 or formed separately and secured thereto, and is similarly formed of an electrically insulating material such fluroethylene copolymer or polytetrafluoroethylene. The shroud 120 comprises a base 121 disposed at a proximal end thereof, which may comprise a planar disc, which extends in a plane substantially transverse to a longitudinal axis of the conduit 1 10. The shroud 120 further comprises a side wall 122 which extends around a periphery of the base 121 , away from the base 121 and the conduit 1 10, to form an enclosure 123. The side wall 122 terminates at an open periphery 124 of the shroud 120 that extends in a plane which is substantially parallel with a plane of the base 121 , and is spaced from the base 121 by approximately 16mm, such that the enclosure 123 forms a cup-shape which is open at a distal end 125 thereof.

Referring to figure 2 of the drawings, the conduit 1 10 and shroud 120 separately comprise a longitudinal axis which extend substantially collinearly. The passageway 1 1 1 of the conduit 1 10 comprises a substantially circular cross-sectional shape and extends out from the proximal and distal end of the conduit to form at an entrance and exit aperture 1 12, 1 13, respectively. The base 121 of the shroud 120 comprises an opening 126 disposed at a central region thereof, which is aligned with the exit aperture 1 13 of the conduit 1 10, to permit the electrode to pass along the passageway 1 1 1 into the enclosure 123. The electrode may comprise an elongate wire or similar and the cross-sectional area of the passageway 1 1 1 reduces from approximately 8mm² at the entrance aperture 1 12 to approximately 4mm² at the exit aperture 1 13, such that radial movement of the electrode becomes reduced along the passageway 1 1 1 . The opening 126 formed in the base 121 is sized and shaped to match the exit aperture 1 13 such that radial movement of the electrode is minimised within the enclosure 1 13. This reduced radial movement maintains a separation of the electrode from the side wall 122 and thus the proximity of the electrode to any electrically conducting surfaces (not shown). In an embodiment, the side wall 122 extends at a radius of at least 3mm from a centre of the opening 126 and more preferably 3-5mm from the central opening 126 to establish a minimum separation of approximately 3-5mm of the electrode from the side wall 122. This separation is found to preserve an electrical potential difference of at least 3kV between the electrode and the surrounding bodies. However, it is to be appreciated that this separation may be varied depending on the particular potential difference required at the electrode.

The electric field is generated from the distal portion of the electrode which extends within the enclosure 123 and the electrode or the shield 100 is sized, such that that a distal end of the electrode is spaced from the open end 125 of the shroud 120 by a least 8mm and from the base 121 by approximately 3-5mm, when fully inserted. This again establishes a minimum separation of the electrode from surrounding bodies, since the shroud 120 acts as a physical barrier to prevent direct contact of any bodies with the electrode. The electric field generated from the distal portion is permitted to pass out from the enclosure 123 via the open end 125 and can thus generate ions in a region directed forwardly of the shroud 120. The electric field emanating from the distal portion of the electrode, out from the enclosure 123, extends through an angular range by virtue of the cross-sectional area of the enclosure 123 which increases from the base 121 to the open end 125 of the shroud 120. The side wall 122, or at least an internal surface thereof, diverge with respect to a longitudinal axis of the shroud 120 by at least 1 °, and typically 1 °-3°, to facilitate a more divergent electric field pattern from the enclosure 123.

Referring to figures 3 and 4 of the drawings, there is illustrated an electrode shield 200 according to a second embodiment of the present invention. The electrode shield 200 of the second embodiment is substantially the same as the electrode shield 100 of the first embodiment and so like features have been referenced using the same numerals but increased by 100. The electrode shield 200 of the second embodiment differs from the first embodiment in that the open periphery 225 of the shroud 220 comprises a plurality of castellations or serrations 227 formed at the distal end of the side wall 222. The castellations 227 extend from the open end 225 of the side wall 222 to a depth of approximately 6mm along the side wall 222, toward the base 221 , and are angularly separated around the side wall 222 such that each castellation 227 comprises a width of approximately 3-4mm and is separated from adjacent castellations 227 by approximately 3-4mm. The castellations 227 serve to maintain a physical barrier between the electrode and any electrically conducting bodies (not shown), to maintain a minimum separation therebetween, while enabling the electric field to spread out from the enclosure 223 through a larger angular range by virtue of the openings 228 between the castellations 227. Referring to figures 5 and 6 of the drawings, there is illustrated an electrode shield 300 according to a third embodiment of the present invention. The electrode shield 300 of the third embodiment is substantially the same as the electrode shield 100 of the first embodiment and so like features have been referenced using the same numerals but increased by 200. The electrode shield 300 of the third embodiment differs from the first embodiment in that the side wall 322 comprises a plurality of windows 329 or openings disposed therein. The windows 329 may comprise a square, circular or rectangular shape for example, and are angularly separated around the shroud 320. In an embodiment, the windows 329 are spaced from the open end 325 of the shroud 320 by approximately 1 .5mm and extend to a depth of approximately 7.5mm from the open end 325. In this respect, it is evident that the windows 329 are disposed preferentially toward the open end 325 of the enclosure 323, beyond the distal end of the electrode. Similar to the electrode shield 200 of the second embodiment, the windows 329 permit the electric field to spread out from the enclosure 323 through a larger angular range to generate ions over a greater volume. The conduit 1 10, 210, 310 associated with the electrode shields 100, 200, 300 of each of the above described embodiments further comprises means 130, 230, 330 for detachably coupling the shield with medical devices, such as a trocar fitment (not shown) for enabling the shield to penetrate a gel membrane cover (not shown) of a medical port (not shown) used in transanal minimally invasive surgery. The means 130, 230, 330 may comprise an external thread 131 , 231 , 331 , such as that associated with the Luer Lok ® and/or an internal taper 132, 232, 332 formed in the passageway 1 1 1 , 21 1 , 31 1 at the entrance aperture 1 12, 212, 312, such as the Luer-Slip ®.

During use, such as when smoke clearing is required in the anal canal during transanal minimally invasive surgery, a trocar fitment (not shown) is coupled to the proximal end of the conduit 1 10 of the shield 100 (of the first embodiment, for example) and used to penetrate a gel membrane cover (not shown) of a medical access port (not shown) from an inner facing side thereof. The proximal end of the conduit 1 10 is thus arranged to extend at an exterior of the port (not shown) and the membrane cover (not shown) is then secured in place upon the port such that the shroud 120 extends at the interior side thereof, within the anal canal.

The trocar fitment (not shown) is then removed from the conduit 1 10 and an electrode (not shown) is inserted within the conduit 1 10 via the entrance aperture 1 12. The electrode is passed along the passageway 1 1 1 and when fully inserted, a distal portion of the electrode is arranged to extend out from the exit aperture 1 13 within the shroud 120, proximate the base 121 . The electrode may then be coupled to a source of electrical potential (not shown) via a connecting wire (not shown) for example, to create a potential difference between the distal portion of the electrode and the surrounding tissue of the anal canal. Medical instruments (not shown) may also be inserted through the gel membrane (not shown) for use in the surgical procedure, and the shield 100 is arranged to maintain a physical separation of the distal portion of the electrode from the medical devices to maintain a suitable potential difference for generating ions within the canal and to further prevent a direct contact between the electrode and the medical instruments which may otherwise lead to an electrostatic discharge.

From the foregoing therefore, it is evident that the shield provides an effective barrier which preserves an electrical potential difference between the electrode and a patient.

Claims

1 . An electrode shield comprising an elongate conduit having a passageway for receiving an electrode, the passageway extending between an entrance aperture disposed at a proximal end of the conduit and an exit aperture disposed at a distal end of the conduit,

2. An electrode shield according to claim 1 , wherein the opening is disposed substantially centrally of the base.

3. An electrode shield according to claim 1 or 2, wherein the conduit and shroud separately comprise a longitudinal axis which are substantially collinear.

4. An electrode shield according to any preceding claim, wherein a cross-sectional area of the passageway reduces along the length thereof, from the entrance to the exit aperture.

5. An electrode shield according to claim 4, wherein a cross-sectional shape and area of the opening substantially matches the cross-sectional shape and area of the exit aperture.

6. An electrode shield according to any preceding claim, wherein the shroud and conduit comprise a substantially circular cross-sectional shape and the side wall of the shroud extends along a radius, around the opening.

7. An electrode shield according to any preceding claim, wherein at least an internal surface of the side wall forming the shroud diverges with respect to a longitudinal axis of the shroud, in a direction which is along the longitudinal axis, away from the base.

8. An electrode shield according to claim 7, wherein the internal surface of side wall extends at an angle of at least 1 ° with respect to the longitudinal axis of the shroud.

9. An electrode shield according to claim 7 or 8, wherein the internal surface of the side wall extends at an angle of 1 °-3° with respect to the longitudinal axis of the shroud.

10. An electrode shield according to any preceding claim, wherein the opening is separated from the side walls by at least 3mm.

1 1 . An electrode shield according to any preceding claim, wherein the opening is separated from the side walls by 3-5mm.

12. An electrode shield according to any preceding claim, wherein the shroud comprises a plurality of windows or holes disposed in the side wall thereof.

13. An electrode shield according to claim 12, wherein the windows are angularly separated around the shroud.

14. An electrode shield according to claim 12 or 13, wherein the windows are disposed closer toward the distal end of the side wall than the base of the shroud.

15. An electrode shield according to any preceding claim, wherein the side wall comprises a plurality of serrations or castellations formed at the distal end thereof.

16. An electrode shield according to any preceding claim, wherein a proximal end of the conduit comprises means for detachably coupling the shield with medical devices.

17. An electrode shield according to any preceding claim, wherein the conduit and shroud at formed of a hydrophobic material.

18. An electrode shield according to any preceding claim, wherein the conduit and shroud are formed of an electrically insulating material.