System and method for dc tissue impedance sensing

Abstract

A system and method for transmitting electrosurgical energy from a generator to an electrosurgical instrument are provided. The electrosurgical system includes a generator adapted to generate electrosurgical energy for treating tissue. The generator includes one or more active output terminals which supply energy to the tissue. The active output terminals are operatively connected to one or more active leads. The generator also includes one or more return output terminals which returns energy from the tissue. The return output terminals are operatively connected to at least one return lead. The system also includes an electrosurgical instrument operatively connected to the one or more active leads and one or more return electrodes operatively connected to one or more return leads. The system further includes an electrosurgical cable including one or more active leads and one or more return leads. The one or more active leads and one or more return leads are wound in a double helix fashion such that the electrical field along the cable is mitigated along the length thereof.

1 - 20 . (canceled) 
     
     
         21 . An electrosurgical generator, comprising:
 a direct current power supply configured to supply direct current;   a radio frequency output stage electrically coupled to the direct current power supply, the radio frequency output stage configured to generate a radio frequency waveform based on the direct current;   a direct current power supply sensor coupled to the direct current power supply and configured to measure at least one property of the direct current; and   a controller configured to derive at least one property of the radio frequency waveform based on a measured property of the direct current.   
     
     
         22 . The electrosurgical generator according to  claim 21 , wherein the radio frequency output stage includes at least one active output terminal and at least one return output terminal. 
     
     
         23 . The electrosurgical generator according to  claim 22 , further comprising:
 a radio frequency output stage sensor coupled to at least one of the at least one active output terminal or the at least one return output terminal and configured to measure at least one property of the radio frequency waveform.   
     
     
         24 . The electrosurgical generator according to  claim 23 , wherein the controller is further configured to compare a derived property of the radio frequency waveform with the measured property of the radio frequency waveform. 
     
     
         25 . The electrosurgical generator according to  claim 24 , wherein the controller is further configured to determine a dosage error based on the comparison. 
     
     
         26 . The electrosurgical generator according to  claim 21 , wherein the radio frequency output stage is disposed within a housing of a handheld electrosurgical instrument. 
     
     
         27 . The electrosurgical generator according to  claim 21 , wherein the handheld electrosurgical instrument is an electrosurgical forceps including at least one shaft member having an end effector assembly disposed at a distal end thereof, the end effector assembly including two jaw members, at least one of the jaw members being movable from a first position in spaced relation relative to the other jaw member to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween, each of the jaw members including an electrically conductive sealing surface. 
     
     
         28 . The electrosurgical generator according to  claim 21 , wherein the controller is further configured to derive the at least one property of the radio frequency waveform based on the measured property of the direct current using a transfer function. 
     
     
         29 . An electrosurgical system, comprising:
 an electrosurgical instrument; and   an electrosurgical generator coupled to the electrosurgical instrument, the electrosurgical generator including:
 a direct current power supply configured to supply direct current; 
 a radio frequency output stage electrically coupled to the direct current power supply, the radio frequency output stage configured to generate a radio frequency waveform based on the direct current; 
 a direct current power supply sensor coupled to the direct current power supply and configured to measure at least one property of the direct current; and 
 a controller configured to derive at least one property of the radio frequency waveform based on a measured property of the direct current. 
   
     
     
         30 . The electrosurgical system according to  claim 29 , wherein the electrosurgical instrument is an electrosurgical forceps including at least one shaft member having an end effector assembly disposed at a distal end thereof, the end effector assembly including two jaw members, at least one of the jaw members being movable from a first position in spaced relation relative to the other jaw member to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween, each of the jaw members including an electrically conductive sealing surface. 
     
     
         31 . The electrosurgical system according to  claim 30 , wherein the radio frequency output stage includes at least one active output terminal and at least one return output terminal, each of which is coupled to one of the electrically conductive sealing surfaces. 
     
     
         32 . The electrosurgical system according to  claim 31 , further comprising:
 a radio frequency output stage sensor coupled to at least one of the at least one active output terminal or the at least one return output terminal and configured to measure at least one property of the radio frequency waveform.   
     
     
         33 . The electrosurgical system according to  claim 32 , wherein the controller is further configured to compare a derived property of the radio frequency waveform with the measured property of the radio frequency waveform. 
     
     
         34 . The electrosurgical system according to  claim 33 , wherein the controller is further configured to determine a dosage error based on the comparison. 
     
     
         35 . The electrosurgical system according to  claim 32 , wherein the controller is further configured to derive the at least one property of the radio frequency waveform based on the measured property of the direct current using a transfer function.