System and method for monitoring electrosurgical instruments

Abstract

A system and method for performing an electrosurgical procedure are disclosed. The method includes applying an active electrode to a patient and placing a return electrode on the patient so as to create a current path in tissue of the patient between the active electrode and the return electrode. A conductive element, which is operatively coupled to the active electrode, is coupled to a reference voltage with a low impedance path and a voltage is imparted to the active electrode so as to generate current in the current path. Any undesirable current flow that would otherwise flow from the active electrode to the reference voltage through the patient is limited to reduce a risk of harm to the patient.

1 . A method for performing an electrosurgical procedure comprising: 
 applying an active electrode to a patient, the active electrode being operatively coupled to a conductive body of a surgical instrument;    placing a return electrode on the patient so as to create a current path in tissue of the patient between the active electrode and the return electrode;    coupling the conductive body to a reference voltage with a low impedance path;    imparting a voltage to the active electrode so as to generate current in the current path, wherein the current in the current path alters some tissue of the patient; and    limiting any undesirable current flow that would otherwise flow, absent the limiting, from the active electrode to the reference voltage through the patient, conductive body and the low impedance path.    
   
   
       2 . The method of  claim 1  including: 
 monitoring, while continuing to impart the voltage to the active electrode, a non-zero level of conduction between the conductive body and the active electrode; and    altering the voltage to the active electrode in response to a variation of the non-zero level of conduction.    
   
   
       3 . The method of  claim 1 , wherein the limiting includes limiting the undesirable current flow with an insulator interposed between the patient and the conductive body.  
   
   
       4 . The method of  claim 1 , wherein the limiting includes limiting a difference between a voltage of the conductive body and a voltage of the patient.  
   
   
       5 . The method of  claim 4 , wherein limiting the difference between the voltage of the conductive body and the voltage of the patient includes the coupling the conductive body to the reference voltage, wherein the reference voltage is substantially the same as the voltage of the patient.  
   
   
       6 . The method of  claim 5 , wherein the coupling includes coupling the conductive body to the patient with the low impedance path, and wherein the reference voltage is the voltage of the patient.  
   
   
       7 . The method of  claim 4 , wherein the reference voltage is a derived reference, wherein the derived reference is derived from at least one physical characteristic of the patient.  
   
   
       8 . The method of  claim 7 , wherein the derived reference is derived so as to render the voltage of the conductive body substantially the same as the voltage of the patient.  
   
   
       9 . The method of  claim 7 , including: 
 measuring an impedance of the patient; and    measuring a return current in the return electrode, wherein the derived reference is derived, at least in part, from the impedance of the patient and the return current in the return electrode.    
   
   
       10 . The method of  claim 7 , wherein the derived reference is derived from a characteristic of the patient selected from the group consisting of a hydration level and a body fat level.  
   
   
       11 . The method of  claim 7 , wherein the derived reference is derived, at least in part, from at least one voltage measurement of at least one portion of the patient.  
   
   
       12 . The method of  claim 6  including: 
 placing, at a distance from the return electrode, a reference electrode on the patient, wherein the reference voltage is a voltage of the reference electrode.    
   
   
       13 . The method of  claim 1 , wherein the coupling includes coupling the conductive body to the return electrode with the low impedance path, wherein the reference voltage is a voltage of the return electrode.  
   
   
       14 . The method of  claim 2 , wherein the monitoring the non-zero level of conduction includes measuring current in the low impedance path.  
   
   
       15 . The method of  claim 2 , wherein the monitoring the non-zero level of conduction includes monitoring a voltage of the conductive body.  
   
   
       16 . The method of  claim 1 , wherein the low impedance path is less than 100 ohms.  
   
   
       17 . The method of  claim 16 , wherein the low impedance path is greater than or equal to 15 ohms and less than or equal to 50 ohms.  
   
   
       18 . The method of  claim 2 , wherein the altering includes modulating, in relation to the non-zero level of conduction, the voltage to the active electrode.  
   
   
       19 . The method of  claim 18 , wherein the modulating includes sustaining a magnitude of the voltage to the active electrode for a predetermined period of time before inhibiting the voltage to the active electrode.  
   
   
       20 . The method of  claim 1 , including: 
 monitoring a level of conduction between a shield and the return electrode, wherein an insulating layer separates the shield from the active electrode and the shield surrounds a substantial portion of the active electrode and the insulating layer; and    altering the voltage to the active electrode in response to the level of conduction between the shield and the return electrode.    
   
   
       21 . The method of  claim 1 , wherein the conductive body is a conductive body selected from the group consisting of an endoscope working element and a conductive body of a colonoscope.  
   
   
       22 . A method for performing an electrosurgical procedure on a patient with an electrosurgical instrument comprising: 
 placing a return electrode between the patient and a return line of an electrosurgical generator;    coupling a conductive body of the electrosurgical instrument to a reference voltage via a low impedance path, wherein the reference voltage is substantially isolated from the return electrode and the reference voltage is selected so as to limit a difference between a patient voltage and a voltage of the conductive body;    coupling an active electrode of the electrosurgical instrument between the patient and an active line of the electrosurgical generator, wherein the electrosurgical generator is capable of providing, to the active electrode, a range of surgical-level voltages that are sufficient to alter tissue of the patient;    detecting undesirable current between the active electrode and the working element; and    imparting a voltage to the active electrode that is within the range of surgical-level voltages while there are tolerable non-zero levels of the undesirable current between the active electrode and the working element.    
   
   
       23 . A system for performing an electrosurgical procedure comprising: 
 an electrosurgical instrument comprising an active electrode and a conductive body, wherein the active electrode is operatively coupled to the conductive body and the active electrode is configured to impart, when coupled with an electrosurgical generator, a voltage to a region of a patient so as to alter tissue in the region of the patient;    a return electrode configured to be coupled between the patient and the electrosurgical generator;    a reference electrode configured to be coupled to the patient so as to attain a patient voltage; and    a monitor coupled between the conductive body of the electrosurgical instrument and the reference electrode, wherein the monitor is configured to monitor a fault current between the conductive body and reference electrode.