Electrosurgical system
View Patent ↗An electrosurgical system includes a generator for generating radio frequency (RF) power, and an electrosurgical instrument including at least three electrodes. The generator comprises an RF output stage having at least a pair of RF output lines, a power supply coupled to the output stage for supplying power to the output stage, and a controller capable of varying the RF power signal supplied to the output lines. The system also includes a selection circuit having at least three output connections each in electrical connection with a respective one of the at least three electrodes. This selection circuit operates to vary the coupling between the RF output stage and the three or more output connections. A switching device operable by the user causes the selection circuit to vary the electrode or electrodes to which RF power is supplied, and also causes the RF power signal supplied to at least one of the at least three output connections to vary depending on the electrode or electrodes to which RF power is supplied. In one arrangement of the selection circuit, one of the electrodes has no direct connection to the output stage of the generator and is connected via a capacitor to another of the electrodes.
1. An electrosurgical system including a generator for generating radio frequency power, and an electrosurgical instrument including at least three electrodes, the generator comprising at least one source of radio frequency (RF) power, and the system also including a selection arrangement operable to vary the coupling between the at least one RF source and the at least three electrodes, the system further including a switching device operable to cause the selection arrangement to vary the electrode or electrodes to which RF power is supplied, the arrangement of the system being such that the RF power signal applied to at least one of the electrodes varies depending on the electrode or electrodes to which radio frequency power is supplied, and also such that one of the electrodes has no direct connection to the output stage of the generator and is connected via a capacitor to another of the electrodes.
2. A system according to claim 1 , wherein:
the source of RF power includes an RF output stage having at least a pair of RF output lines;
the generator includes a controller capable of varying the RF power signal supplied to the output lines;
the selection arrangement comprises a switching circuit having at least three output connections each in electrical connection with a respective one of the at least three electrodes, and is operable to vary the connections between the RF output lines and the output connections; and
the switching device is operable to cause the RF power signal applied to at least one of the three or more output connections to vary depending on the electrode or electrodes to which radio frequency power is supplied.
3. A system according to claim 2 , wherein the RF output stage of the generator is coupled to an RF driver and the controller is capable of varying an RF signal applied by the driver to the RF output stage.
4. A system according to claim 2 , wherein the controller automatically adjusts the RF power supplied to at least one of said output connections to limit the peak generator output voltage to at least a first value when operation of the switching device causes RF power to be fed to a first combination of electrodes, and to at least a second value when operation of the switching device causes RF power to be fed to a second combination of electrodes.
5. A system according to claim 1 , wherein the capacitor has a value of between 1 and 10 nF.
6. A system according to claim 1 , wherein two of the three or more electrodes are in the form of jaws adapted to grasp tissue therebetween.
7. A system according to claim 6 , wherein the third electrode is mounted on one of the jaws, separated therefrom by an insulating member.
8. A system according to claim 7 , wherein the third electrode is mounted on an external face of one of the jaws.
9. A system according to claim 7 , wherein the third electrode is mounted on an internal face of one of the jaws.
10. A system according to claim 7 , wherein the third electrode is mounted at the tip of one of the jaws.
11. A system according to claim 1 , wherein at least one of the electrodes is in the form of a hook.
12. A system according to claim 11 , wherein at least one hook electrode extends distally beyond the other electrodes.
13. A system according to claim 12 , wherein there is a centrally positioned electrode extending distally beyond the other electrodes.
14. A system according to claim 11 , wherein at least three of the electrodes are in the form of a hook.
15. A system according to claim 1 , wherein at least one of the electrodes is longitudinally movable such that it can be extended and retracted with respect to the other electrodes.
16. A system according to claim 15 , wherein the longitudinally movable electrode is positioned centrally between the other electrodes.
17. A system according to claim 1 , wherein the RF source and selection arrangement are such that the output stage supplies RF power to at least three electrodes simultaneously, the output voltage being limited to a first peak value between a first combination of electrodes, and to a second peak value between a second combination of electrodes.
18. A system according to claim 17 , wherein, in a first mode of operation, a first one of the electrodes has no direct connection to the RF source of the generator and is connected via a capacitor to another of the electrodes, and, in a second mode of operation, a second one of the electrodes has no direct connection to the output stage of the generator and is connected via a capacitor to another of the electrodes.
19. A system according to claim 1 , wherein the selection arrangement is located within the generator.
20. A system according to claim 1 , wherein the selection arrangement is located within the electrosurgical instrument.