GB2261379A

GB2261379A - Electrosurgery apparatus associated with a video camera

Info

Publication number: GB2261379A
Application number: GB9222309A
Authority: GB
Inventors: Keith Hannant; Geoffrey Percy Taylor
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 1991-11-12
Filing date: 1992-10-23
Publication date: 1993-05-19
Anticipated expiration: 2012-10-23
Also published as: GB2261379B; GB9222309D0

Abstract

An electrosurgery system includes a power supply 10, an endoscope 21, a video camera 22 and a display 24. The power supply supplies pulses of RF current synchronised 11 with the camera so that interference from the pulses occurs on the peripheral regions 28 of the display surrounding the desired image 27. A mask may be used to cover the peripheral regions and hence mask the interference. <IMAGE>

Description

ELECTROSURGERY SYSTEM This invention relates to an electrosurgery system including electrosurgery apparatus and a video camera.

Electrosurgery, such as diathermy, units are often used during surgery such as to cut tissue and coagulate blood vessels. Radio frequency current is supplied via a hand-held electrode that is applied to the surgical site; a return path is provided from the patient by means of a large area electrode fixed to some other part of the patient's body. Electrosurgery is particularly useful for operations on internal organs where access is restricted. Such operations are commonly carried out under observation by a television camera coupled to an endoscope, the camera's video output being supplied to a monitor by which progress of the operation can be viewed. One problem with this arrangement is that the electrosurgery output can interfere with the video output, especially in some modes, such as the spray coagulation mode.This can make observation very difficult, especially in view of the fact that the area of the image of interest on the monitor screen is generally confined to a circular region at the centre of the screen. Although it is possible to screen electrically the electrosurgery apparatus and the cables leading to the electrodes, it will be appreciated that it is inherent that the electrodes must be exposed so that they can be brought into contact with patient tissue, and also that there will be an unscreened path for electrical energy through the body.

Several proposals have been made to reduce the effects of this interference. In US 4,517,976 there is described a synchronized system in which electrosurgery current is only applied during the horizontal blanking period, or flyback, of the video signal. This ensures that no interference is produced on the screen but it has the disadvantage that the time period during which electrosurgery signals can be produced is severely limit, thereby reducing the effectiveness of the electrosurgery.

In EP 429204A there is described another synchronized system but, in this case, the synchronization is selected so that interference is visible on the screen but is confined to two vertical bands down opposite edges of the screen. The effect of the interference is reduced because the regions in which interference is produced is confined outside the central region of interest. This arrangement enables the electrosurgery current to be generated during longer time periods but there is still an appreciatable time period during each video scan in which the electrosurgery current must be blocked.

It is an object of the present invention to provide a system including electrosurgery apparatus by which the effects of interference on a video signal are reduced whilst enabling a minimum interruption in the electrosurgery current.

According to one aspect of the present invention there is provided a system including electrosurgery apparatus and a video camera arranged to provide video output signals for display in a region of a display, the electrosurgery apparatus including a power supply unit arranged to supply pulses of high frequency power to an active patient electrode, and synchronization means having an input adapted to receive a synchronization pulse derived from the video camera, and the synchronization means being arranged to synchronize the generation of the pulses to the camera output such that interference is limited to peripheral regions of the display representation, the peripheral regions varying in width along their length substantially to fill. that part of the display not occupied by the region of the display in which the video camera output of interest is represented.

In this way, the time for which electrosurgery pulses can be supplied to the electrode is maximized without any interference being produced in the region of the screen of interest.

The region of the display in which the output signals of interest from the video camera are represented may be of circular shape with a diameter less than both the height and width of the screen on which the signals are represented. In this case, the peripheral region extends entirely across the width of the screen at the top or bottom at least of the screen. The system may include a screen on which the video signals are represented and a mask corresponding in shape to the peripheral regions so that the interference in the peripheral regions is not visible to the user.

The system may include user-operable means for varying the size of the peripheral regions.

A system including electrosurgery apparatus and a video camera, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows the system schematically; Figure 2 illustrates a display produced by an output of the camera; Figures 3 and 4 illustrate different displays; and Figure 5 shows a display screen with a mask.

The electrosurgery/diathermy apparatus is contained in a housing 1 and is connected to an active patient electrode 2 and a large area, return electrode 3. The housing 1 contains a power supply 10 which may be of conventional kind and includes the usual control and safety features to be found on such equipment. One example of a suitable power supply is described in GB 2225656. The housing 1 also includes a synchronization unit 11 which controls the generation of pulses produced by the power supply. The synchronization unit 11 is connected via a cable 12 to video monitoring apparatus 20 forming a part of the system.

The apparatus 20 comprises a conventional fibre-optic endoscope 21 having a television or video camera 22 coupled at its rear end which provides a video output on line 23 to a visual display monitor 24 having a screen 25. The video output can also be supplied to a recorder 26. The cable 12 is coupled to line 23 so that information about both the line number and video synchronization pulses produced by the camera 22 are supplied to the sychronization unit 11 in the electrosurgery housing 1. The periodicity of the video screen is 64 microseconds per line with approximately 52 microseconds appearing on the screen 25 of the monitor 24.The nature of the fibre-optic endoscope 21 is such that the image of the surgical site, as seen through the endoscope and as presented on the monitor 24, is a circular region 27 in the centre of the monitor, the diameter of which is less than both the height and width of the screen 25. The surrounding, peripheral region 28 of the display representation is blank.

The synchronization unit 11 is arranged to control the power supply 10 such that the electrosurgery pulses are only produced at times when the interference that they cause to the display is limited to the blank, peripheral regions 28 and thereby avoids obscuring the central region 27 of interest, that is, the region in which the image of the surgical site is presented.

More particularly, the synchronization unit 11 is programmed with information about the size and location of the circular region 27 of interest to the user. This information may be preset, if the system is always used with the same camera and endoscope, or may be controlled by the user by means of a user-operable control 29. The synchronization unit 11 is arranged so that the width of the peripheral regions in which interference can be produced varies along the length of the regions, that is, along the height of the screen 25. At the top and bottom of the screen 25, it can be seen that there is a gap of several lines between the central region 27 of interest and the edge of the screen. The time occupied by these lines can, therefore, be utilized for the generation of electrosurgery pulses.The control 29 can be varied by the surgeon during use, if desired, either to improve the efficiency of the electrosurgery apparatus, by allowing some encroachment of interference into the central display region 27 where this is acceptable, or to increase the size of the display region that is free of interference, at the expense of a reduction in the efficiency of the electrosurgery apparatus.

A normal spray coagulation output from electrosurgery apparatus would consist of sequence of single pulses with a fundamental frequency of approximately f OOkHz having a pulse separation of about 32 microseconds. The synchronization unit 11 is arranged such that two electrosurgery pulses can be produced along each line with a spacing of 32 microseconds. For example, the pulses might be produced 16 microseconds and 48 microseconds along the line of 64 microseconds. At lines closer towards the centre of the screen which include the circular region 27, the synchronization unit 11 is arranged such that the pulses are generated for as many lines as possible with the desired spacing of 32 microseconds.Midway down the screen 25, where the central region 27 has its maximum width, it may be necessary to reduce or increase the spacing between pulses below or above the preferred spacing. Because the width of the region in which the pulses are generated is varied along its length, this maximises the time for which the pulse separation is at its optimum and hence maximises the efficiency of the apparatus. In this example, it should be noticed that the spacing between pulses is approximately equal to the diameter of the central region 27 but the advantages of the invention are even greater where the optimum spacing between the pulses for the desired surgical effect is appreciably greater or less than the width of the region of the display of interest.Where the desired spacing between pulses is short, it is possible to generate considerably more pulses during one video frame period than in previous proposed systems in which interference was confined either to the flyback period or to two narrow vertical bands on the screen of constant width along their length. Where the desired spacing between the pulses is long compared with the width of the region of interest, the present invention enables a maximum proportion of the pulses to be produced at their optimum spacing because the spacing need only depart from the optimum in the region midway up the screen, where the endoscope display has its maximum width.

It will be appreciated that it is not essential for the diameter of the circular region to be less than the height of the screen. The invention will also have advantages where the region 27' of the display in which the output of the video camera is represented extends to the top and bottom edges of the screen as shown in Figure 3. Furthermore, the display region 27" need not be circular and need not be located centrally of the screen, as shown in Figure 4.

In order to improve the appearance of the screen 25, a mask 30 can be used to cover the peripheral regions of the. screen in which the interference occurs, as shown in Figure 5.

The mask has a central circular aperture 31 of substantially the same diameter as the region of interest seen through the endoscope. The mask 30 may take the form of a card or adhesive sheet applied to the outside surface of the screen. Different endoscopes and cameras may be provided with an appropriate different mask for the user to place on the screen and remove after use. Alternatively, where the screen is always used with a camera and endoscope that produce a region of interest of the same size and position, a mask may be permanently applied to the screen such as by painting or printing. A mask could, alternatively, be applied to the inside of the screen either on top of the phosphor layer, to prevent electrons falling on the phosphor, or underneath the phosphor to prevent light from the phosphor emerging from the screen.

Claims

1. A system including electrosurgery apparatus and a video camera arranged to provide video output signals for display in a region of a display, the electrosurgery apparatus including a power supply unit arranged to supply pulses of high frequency power to an active patient electrode, and synchronization means having an input adapted to receive a synchronization pulse derived from the video camera, wherein the synchronization means is arranged to synchronize the generation of the pulses to the camera output such that interference is limited to peripheral regions of the display representation, and wherein the peripheral regions vary in width along their length substantially to fill that part of the display not occupied by the region of the display in which the video output of interest is represented.

2. A system according to Claim 1, wherein the region of the display in which the output signals of interest from the video camera are represented is of circular shape.

3. A system according to Claim 2, wherein the diameter of the circular shape is less than both the height and width of the screen on which the signals are represented.

4. A system according to Claim 3, wherein a peripheral region extends across the width of the screen at the top or bottom at least of the screen.

5. A system according to any one of the preceding claims including a screen on which the video signals are represented and a mask corresponding in shape to the peripheral regions so that interference in the peripheral regions is not visible to the user.

6. A system according to any one of the preceding claims including user-operable means for varying the size of the peripheral regions.

7. A system substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

8. A system substantially as hereinbefore described with reference to Figures 1 and 2 as modified by any one of Figures 3 to 5 of the accompanying drawings.

9. Any novel feature or combination of features as hereinbefore described.