Electrosurgery system

Abstract

An electrosurgery system includes an electrosurgical generator ( 10 ) coupled to or part of an electrosurgical instrument, the generator being operable to generate electrosurgical power in low frequency (typically at 1 MHz) and high frequency bands (typically at 2.45 GHz) either simultaneously or individually. The generator includes a load-responsive control circuit which, in one mode, causes power to be generated predominantly at 1 MHz when the load impedance is high and predominantly at 2.45 MHz when it is low. This allows automatic switching between cutting and coagulation operation. In one embodiment, the instrument includes a gas plasma generator operating such that an ionisable gas is energised in a gas supply passage by the 2.45 GHz component to form a plasma stream which acts as a conductor for delivering the 1 MHz component to a tissue treatment outlet of the passage.

1 . An electrosurgery system comprising an electrosurgical generator, a feed structure and an electrode assembly, the electrode assembly having at least one active electrode and at least one adjacent return electrode, each of which is coupled to the generator via the feed structure, wherein the feed structure comprises an adder, the generator and feed structure are capable of delivering radio frequency (r.f.) power to the active and return electrodes in lower and upper frequency ranges, the upper range containing frequencies at least three times the frequencies of the lower frequency range, and the adder linearly adds the lower and upper frequency ranges such that the generator and feed structure deliver r.f. power to the electrodes in the lower and upper frequency ranges simultaneously.  
   
   
       2 . A system according to  claim 1 , wherein the lower frequency range is 100 kHz to 100 MHz and the upper frequency range is 300 MHz to 10 GHz.  
   
   
       3 . A system according to  claim 2 , wherein upper frequency range is above 1 GHz and the operating frequencies in the said upper and lower ranges have a frequency ratio of 5:1 or greater.  
   
   
       4 . A system according to  claim 2 , wherein the generator is arranged such that the r.f. power delivered in the upper frequency range is at a fixed frequency which is at least ten times the frequency of r.f. power delivered in the lower frequency range.  
   
   
       5 . A system according to  claim 4 , wherein the fixed frequency is fixed to the extent that it remains within 50 MHz of 2.45 GHz.  
   
   
       6 . A system according to  claim 1 , comprising a supply unit, a handpiece, and a cable connecting the handpiece to the supply unit, wherein: 
 the electrode assembly is mounted in the handpiece,    the generator has first and second stages for generating power in the lower and upper frequency ranges respectively, both stages being contained in the supply unit, and    the supply unit and the cable are configured such that power is supplied to the handpiece in both the lower and the upper frequency range via the cable.    
   
   
       7 . A system according to  claim 1 , comprising a supply unit, a handpiece, and a cable connecting the handpiece supply unit, wherein 
 the electrode assembly is mounted in the handpiece, and    the generator has first and second stages for generating power in the lower and upper frequency ranges respectively, the first stage being contained in the supply unit and the second stage being contained in the combination of the handpiece and the electrode assembly.    
   
   
       8 . A system according to  claim 1 , wherein the feed structure comprises: 
 a rigid or resilient coaxial feed supporting the electrodes at a distal end, the coaxial feed having an inner supply conductor and an outer supply conductor, and    an isolating choke element in the form of a conductive sleeve connected to the outer supply conductor in the region of the said distal end, and having an axial length which is an odd number multiple (1, 3, 5, . . . ) of a quarter wavelength at an operating frequency of the generator in the upper frequency band.    
   
   
       9 . A system according to  claim 1 , wherein the return electrode comprises a conductive sleeve.  
   
   
       10 . A system according to  claim 9 , wherein: 
 the active electrode comprises a rod projecting from the conductive sleeve;    the feed structure comprises a rigid or resilient coaxial feed; and    the active electrode and the return electrode are connected to the inner and outer conductors respectively of the feed at its distal end, and extend respectively distally and proximally with respect to the said connection to form a dipole at an operating frequency of the generator in the upper frequency range.    
   
   
       11 . A system according to  claim 1 , wherein the return electrode is covered with a electrically insulative layer.  
   
   
       12 . A system according to  claim 1 , wherein the electrode assembly includes a gas supply passage and the active electrode is located in the passage to act as a gas ionising electrode.  
   
   
       13 . A system according to  claim 12 , wherein the active electrode is capacitively coupled to the return electrode.  
   
   
       14 . A system according to  claim 1 , wherein the electrode assembly includes a gas supply passage and the active electrode is located in the passage to act as a gas ionising electrode, and wherein the active electrode is an elongate conductor having an electrical length in the region of a quarter wavelength at the operating frequency of the generator in the upper frequency range.  
   
   
       15 . A system according to  claim 1 , wherein: 
 the adder comprises a low frequency input that inputs the r.f. power in the low frequency range to the adder, a high frequency input that inputs the r.f. power in the high frequency range to the adder, and an output that delivers the r.f. power from the adder to the electrodes in the lower and upper frequency ranges simultaneously;    the adder isolates the input r.f. power in the low frequency range from the high frequency input; and    the adder isolates the input r.f. power in the high frequency range from the low frequency input.    
   
   
       16 . A dual frequency electrosurgical system configured to perform electrosurgical cutting or vaporisation at a first frequency within a lower frequency range and electrosurgical coagulation at a second frequency within an upper frequency UHF range, wherein the electrosurgical system comprises an adder that linearly adds the lower and upper frequency ranges to deliver r.f. power to electrodes in the lower and upper frequency ranges simultaneously.  
   
   
       17 . A system according to  claim 16 , wherein the first frequency is within the range of from 100 kHz to 5 MHz and the second frequency is within the range of from 300 MHz to 10 GHz.  
   
   
       18 . An electrosurgical system comprising an electrode assembly with at least a pair of electrodes for receiving radio-frequency electrosurgical power, and a gas supply passage containing at least one of the said electrodes, the arrangement of the electrodes and the passage being such that when the electrodes are energised with sufficient radio frequency power at an upper frequency in the range of from 300 MHz to 10 GHz, and when an ionisable gas is passed through the passage, a gas plasma is formed in the passage, the electrosurgical system comprises an adder that linearly adds the lower and upper frequency ranges to deliver r.f. power to electrodes in the lower and upper frequency ranges simultaneously.  
   
   
       19 . A system according to  claim 18 , wherein the passage terminates in a distal nozzle downstream of the said at least one electrode.  
   
   
       20 . A system according to  claim 18 , wherein the electrode assembly is part of a sterilised electrosurgical device.  
   
   
       21 . A system according to  claim 18 , including a generator coupled to the electrodes and operable to generate electrosurgical power at a frequency in the range of from 300 MHz to 10 GHz.