GB2549992A

GB2549992A - Electrosurgical instrument

Info

Publication number: GB2549992A
Application number: GB1607982.4A
Authority: GB
Inventors: John Keogh Richard
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2016-05-06
Filing date: 2016-05-06
Publication date: 2017-11-08
Anticipated expiration: 2036-05-06
Also published as: GB201607982D0; GB2549992B

Abstract

An electrosurgical instrument is provided for the treatment of tissue, the instrument 1 comprising a handle 2, an instrument shaft 5 extending from the handle and an electrode assembly 6 at the distal end of the shaft. The electrode assembly comprises a tissue treatment electrode 10 and a return electrode 12 that is electrically insulated from the tissue treatment electrode by means of an insulation member 13. The tissue treatment electrode 10 has an exposed surface for treating tissue, where the return electrode 12 has a fluid contact surface that in use define a conductive fluid path that completes an electrical circuit between the electrodes 10&12. The instrument shaft 5 provides a conductive pathway for one of the electrodes and is subjected to a surface treatment so that its surface 7 has been altered whilst maintaining its electrical conductivity. The surface of the instrument shaft 5 may be: oxidised, coloured or matt finished by the surface treatment. The surface treatment may be selected from a list of treatments including phosphate conversion coating, zinc or manganese phosphating, black oxide conversion coating, chrome or nickel plating, or ferritic itrocarburising. The surface treatment may comprise depositing a coating on the instrument shaft 5.

Description

ELECTROSURGICAL INSTRUMENT

This invention relates to an electrosurgical instrument for the treatment of tissue. Such systems are commonly used for the vaporisation and/or coagulation of tissue in surgical intervention, most commonly in “keyhole” or minimally invasive surgery, but also in “open” surgery.

One type of electrosurgical instrument has an instrument shaft which is electrically conductive, and the shaft is used either as one of the electrosurgical electrodes, or as a way of transferring electrosurgical energy from the distal end of the instrument to one of the electrodes at the distal end of the instrument. Whichever arrangement is employed, the majority of the shaft is covered with a sleeve of insulating material, so that only the electrode or a designated part of the shaft constituting the electrode is exposed.

The present invention attempts to provide an alternative to this type of electrosurgical instrument, and comprises an electrosurgical instmment for the treatment of tissue in the presence of an electrically-conductive fluid medium, the instrument comprising a handle, an instrument shaft extending from the handle, and an electrode assembly at the distal end of the shaft, the electrode assembly comprising a tissue treatment electrode and a return electrode which is electrically insulated from the tissue treatment electrode by means of an insulation member, the instrument including first and second connections by which the tissue treatment electrode and the return electrode may be connected to a source of electrosurgical energy, the tissue treatment electrode having an exposed surface for treating tissue, and the return electrode having a fluid contact surface so as to define, in use, a conductive fluid path that completes an electrical circuit between the tissue treatment electrode and the return electrode, wherein the instrument shaft provides a conductive pathway between one of the electrodes and one of the first and second connections, characterised in that the instrument shaft has been subjected to a surface treatment such that its surface has been altered while maintaining its electrical conductivity.

Preferably, the surface treated shaft is exposed along a majority of its length. The invention relies on the surprising realisation that it is not necessary to cover the conductive shaft with an insulating sleeve such as a heat-shrink polymer sleeve. Damage to the polymer sleeve can lead to debris being generated which can create problems during a surgical procedure, in extreme cases leading to small pieces of polymer finding their way into the patient’s body. In addition, if damage or wear to the polymer sleeve results in pin-holes in the sleeve, this can result in areas of high electric field leading to current leakage and the possibility of thermal burns to the patient. Replacing the insulating sleeve with a surface treatment reduces these potential problems. Conceivably, the surface treated shaft is exposed along its entire length.

It is still advantageous to ensure that the surface treated shaft is visibly different from the other surrounding areas of the instrument, such that the surgeon can clearly establish which areas are intended to contact tissue and which areas are not. Therefore, the surface treatment conveniently provides a matt finish for the instrument shaft. Alternatively or additionally, the surface treatment conceivably provides a coloured finish, the colour of the surface being different from that of the original instrument shaft.

According to one convenient arrangement, the surface treatment results in the surface of the shaft being oxidised. Suitable surface treatment techniques include conversion coating processes such as phosphate conversion coating (typically zinc or manganese phosphating), black oxide conversion coating, or chrome or nickel plating. Also possible is ferritic nitrocarburising (salt bath, plasma or gaseous nitrocarburising). Whichever process is used, the treatment alters the physical appearance of the shaft, while maintaining its electrical conductivity. Alternatively or additionally, the surface treatment comprises depositing a coating on the instrument shaft.

The invention will now be further described, by way of example only, with reference to the accompanying drawings in which;

Figure lisa schematic side view of an electrosurgical instrument in accordance with the present invention, and

Figure 2 is an enlarged view of the distal tip of the instrument of Figure 1.

Referring to Figure 1, an electrosurgical instrument is shown generally at 1, and includes an instrument handle 2, cord 3 and plug 4. Extending distally from the handle 2 is an instrument shaft 5, and a bipolar electrode assembly 6 is present at the distal end of the shaft. The shaft 5 has been subjected to a surface treatment process such that its surface 7 has been oxidised. The surface 7 has a matt finish, and has a colour different from that of the steel shaft itself. A suction tube 8 and suction connector 9 complete the instrument 1, forming a suction path through the instrument 1.

Figure 2 shows the tip of the instrument 1. A tissue treatment electrode 10 is present at the tip of the instrument, and forms the active electrode in the bipolar electrode assembly 6. As previously described, the surface of the instrument shaft 5 has been oxidised, but one area 11 is left unoxidised to form the return electrode 12 for the electrode assembly 6. A ceramic insulating housing 13 separates the tissue treatment electrode 10 from the shaft 5. The tissue treatment electrode 10 has suction apertures 14, forming a suction pathway from the tissue treatment electrode 10, through the hollow shaft 5, through the handle 2 and out through the suction tube 8.

In use a source of electrosurgical energy is supplied to the electrode assembly 6. The instrument is typically used submerged in an electrically conductive fluid, such as normal saline, with the RF energy flowing from the tissue treatment electrode 10, through the conductive liquid to the return electrode 12, with any tissue entering the region of the tissue treatment electrode 10 being vaporised or coagulated depending on the circumstances. Although the oxidised area of the shaft 5 is electrically conductive, if the shaft inadvertently comes into contact with tissue, its distance from the tissue treatment electrode 10 means that little or no current will flow into the tissue. Thus, patient safety is maintained and there is no need for a polymeric heat-shrink sleeve to be provided covering the shaft 5.

Alternative embodiments will be envisaged by those skilled in the art without departing from the scope of the present invention. For example, rather than using an unoxidised region of the instrument shaft as a return electrode, the whole of the conductive shaft can be oxidised, with the distal end of the oxidised shaft constituting the return electrode. Alternatively, the oxidised shaft can be used as a lead to conduct electrosurgical current from a separate return electrode mounted on the shaft. Whichever type of instrument is employed, the shaft 5 does not have an insulating sleeve fitted thereto, the oxidised surface 7 being sufficient to visibly distinguish those areas of the instrument designed for tissue contact from other areas of the instrument not intended for tissue contact.

Claims

1. An electrosurgical instrument for the treatment of tissue in the presence of an electrically-conductive fluid medium, the instrument comprising a handle, an instrument shaft extending from the handle, and an electrode assembly at the distal end of the shaft, the electrode assembly comprising a tissue treatment electrode and a return electrode which is electrically insulated from the tissue treatment electrode by means of an insulation member, the instrument including first and second connections by which the tissue treatment electrode and the return electrode may be connected to a source of electrosurgical energy, the tissue treatment electrode having an exposed surface for treating tissue, and the return electrode having a fluid contact surface so as to define, in use, a conductive fluid path that completes an electrical circuit between the tissue treatment electrode and the return electrode, wherein the instrument shaft provides a conductive pathway between one of the electrodes and one of the first and second connections, characterised in that the instrument shaft has been subjected to a surface treatment such that its surface has been altered while maintaining its electrical conductivity.

2. An electrosurgical instrument according to claim 1, wherein the surface treated shaft is exposed along the majority of its length.

3. An electrosurgical instrument according to claim 2, wherein the surface treated shaft is exposed along its entire length.

4. An electrosurgical instrument according to any of claims 1 to 3, wherein the surface treatment provides a matt finish for the instrument shaft.

5. An electrosurgical instrument according to any of claims 1 to 4, wherein the surface treatment provides a coloured finish, the colour of the surface being different from that of the original instrument shaft

6. An electrosurgical instrument according to any preceding claim, wherein the surface treatment results in the surface of the shaft being oxidised.

7. An electrosurgical instrument according to any preceding claim, wherein the surface treatment is selected from a list of treatments including phosphate conversion coating, zinc or manganese phosphating, black oxide conversion coating, chrome or nickel plating, or ferritic nitrocarburising.

8. An electrosurgical instrument according to any of claims 1 to 5, wherein the surface treatment comprises depositing a coating on the instrument shaft.