Automatic control for energy from an electrosurgical generator

• US 6,210,403 B1
• Filed: 10/07/1993
• Issued: 04/03/2001
• Est. Priority Date: 10/07/1993
• Status: Expired due to Term

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Sherwood Services AG
• Inventors: Klicek, Michael S.
• Primary Examiner(s): Shay, David M.
• Application Number:
  US08/132,940
• Time in Patent Office: 2,735 Days
• Field of Search: 606/32, 606/34, 606/35, 606/37-42
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00755 Resistance or impedance
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00779 Power or energy
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00892 Voltage

Abstract

An electrosurgical generator control responds to tissue impedance between active and return electrodes during desiccation. Active and return generator leads to supply energy and a user control sets the level of energy desired for electrosurgery. Voltage and current sensing circuits respond to high frequency energy in the leads to signal voltage and current in the leads. A multiplier receives the signals to calculate power. A clock sets units of time during for which power calculation. An integrator calculates the energy supplied through the leads per time unit. The user control sets a reference signal for the energy level desired. A correlation circuit receives the energy calculations from the integrator and the reference signal and provides a feedback signal to indicate when the energy calculation equals the user control setting for altering the generator supply of energy to the leads. A counter assesses the number of packets of energy delivered against a setting of the user control and the total energy delivered is a function of multiple packet sequences containing pulses wherein the time between the pulses is controlled by the user control. The method uses the automatic control in measuring impedance during tissue desiccation and altering the output of an electrosurgical generator.

Claims

1. An electrosurgical generator responsive to levels of tissue impedance between an active electrode and a return electrode wherein each electrode is electrically connected to the electrosurgical generator comprising:

an active lead and a return lead, each electrically connected to the electrosurgical generator to supply high frequency electrosurgical energy in the form of at least one energy packet;

a user control, electrically connected to the electrosurgical generator, for setting a preset level of energy desired for electrosurgery and for setting a reference signal in the electrosurgical generator indicative of the preset energy level desired by the user;

said user control further comprising a first adjuster for setting a total number of energy packets and a second adjuster for setting a time between delivery of energy packets;

an automatic control circuit, electrically connected to the electrosurgical generator;

a voltage sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the leads, the voltage sensing circuit capable of providing a signal of voltage level between the active and return leads;

a current sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the return lead, the current sensing circuit capable of providing a signal of current level;

a multiplier, within the automatic control circuit, connected to the voltage and current sensing circuits to receive the signals from the voltage and current sensing circuits and to multiply those signals together for calculating power flow through the leads of the electrosurgical generator;

a clock, within the automatic control circuit, connected to the multiplier and the electrosurgical generator, the clock for establishing units of time during which power flow calculated by the multiplier is considered;

an integrator, within the automatic control circuit, joined to the multiplier and the clock and responsive thereto, the integrator to calculate an amount of energy supplied through the leads per each unit of time established by the clock based on power flow calculations of the multiplier, and

a correlation circuit, within the automatic control circuit, coupled to the integrator to receive the amount of energy calculated from the integrator and the reference signal in accord with the setting of the user control to which the correlation circuit is connected, the correlation circuit electrically connected to the electrosurgical generator to provide a feedback signal to indicate when the amount energy calculated equals the reference signal of the user control setting for altering the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads responsive to impedance changes between active and return electrodes during tissue desiccation.

2. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 1 wherein a comparator in the correlation circuit is connected to receive the energy calculations from the integrator and the reference signal in accord with the setting of the user control, the comparator to provide the feedback signal to indicate when the energy calculation equals the user control setting for terminating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads so the supply of high frequency is automatically adjusted.

3. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 1 wherein a differential amplifier in the correlation circuit is connected to receive the energy calculations from the integrator and reference signal in accord with the setting of the user control, the differential amplifier to provide feedback quantity as a measure of the difference between the energy calculations and the user control setting for matching the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads is automatically adjusted in accord with the feedback quantity to narrow the difference between the energy calculations and the setting of the user control.

4. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 1 wherein the clock has structure that sets units of time which are about a millisecond thus providing feedback useful for immediate use in real time to the electrosurgical generator for regulating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads.

5. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 1 wherein the electrosurgical generator output is terminated in response to said feedback signal by altering a drive circuit in the electrosurgical generator thereof so the supply of high frequency electrosurgical energy to the active and return leads is terminated.

6. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 1 wherein the integrator has a place therein that calculates the energy applied over each unit of time established by the clock during the operation of the electrosurgical generator.

7. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 6 wherein a bipolar electrode configuration connects the active and return leads for use on the tissue.

8. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 6 wherein a monopolar electrode is connected to the active lead for use on the tissue.

9. An electrosurgical generator responsive to levels of tissue impedance between an active electrode and a return electrode wherein each electrode is electrically connected to the electrosurgical generator comprising:

an active lead and a return lead wherein each electrically connected to the electrosurgical generator to supply high frequency electrosurgical energy;

a user control, electrically connected to the electrosurgical generator, for setting a preset level of energy desired for electrosurgery and for setting a reference signal in the electrosurgical generator indicative of the preset energy level desired by the user;

an automatic control circuit, electrically connected to the electrosurgical generator;

a voltage sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the leads, the voltage sensing circuit capable of providing a signal of voltage level between the active and return leads;

a current sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the return lead, the current sensing circuit capable of providing a signal of current level;

a multiplier, within the automatic control circuit, connected to the voltage and current sensing circuits to receive the signals from the voltage and current sensing circuits and to multiply those signals together for calculating power flow through the leads of the electrosurgical generator;

a clock, within the automatic control circuit, connected to the multiplier and the electrosurgical generator, the clock for establishing units of time during which power flow calculated by the multiplier is considered;

an integrator, within the automatic control circuit, joined to the multiplier and the clock and responsive thereto, the integrator to calculate an amount of energy supplied through the leads per each unit of time established by the clock based on power flow calculations of the multiplier;

a correlation circuit, within the automatic control circuit, coupled to the integrator to receive the amount of energy calculated from the integrator and the reference signal in accord with the setting of the user control to which the correlation circuit is connected, the correlation circuit electrically connected to the electrosurgical generator to provide a feedback signal to indicate when the amount energy calculated equals the reference signal of the user control setting for altering the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads responsive to impedance changes between active and return electrodes during tissue desiccation; and

wherein the user control has two added adjusters one for setting a number of packets of energy and another for setting a preset level of energy delivered per packet.

10. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 9 wherein a counter in the electrosurgical generator assesses the number of packets of energy delivered against the setting of the one adjuster of the number of packets, as established by the user control, with a second comparator.

11. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 9 wherein the adjuster for energy level per packet includes a potentiometer that provides a direct current voltage as the reference signal of energy level.

12. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 10 wherein the counter in the electrosurgical generator assesses the number of packets of energy delivered against the setting of the adjuster of the number of packets as established by the user control with the second comparator and the total energy delivered is a function of multiple packet sequences containing pulses wherein the time between the pulses is controlled by the user control.

13. An electrosurgical generator setting responsive to levels of tissue impedance between an active electrode and a return electrode wherein each electrode is electrically connected to the electrosurgical generator comprising:

an active lead and a return lead wherein each electrically connected to the generator to supply high frequency electrosurgical energy in the form of at least one energy packet;

a user control, electrically connected to the electrosurgical generator, for a preset level of energy desired for electrosurgery and for setting a reference signal in the electrosurgical generator indicative of the preset energy level desired by the user;

said user control further comprising a first adjuster for setting a total number of energy packets and a second adjuster for setting a time between delivery of energy packets;

an automatic control circuit, electrically connected to the electrosurgical generator;

a voltage sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the leads, the voltage sensing circuit capable of providing a signal of voltage level between the active and return leads;

a current sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the return lead, the current sensing circuit capable of providing a signal of current level;

a multiplier, within the automatic control circuit, connected to the voltage and current sensing circuits to receive the signals from the voltage and current sensing circuits and to multiply those signals together for calculating power flow through the leads of the electrosurgical generator;

a clock, within the automatic control circuit, for establishing units of time during which power flow calculated by the multiplier is considered, the clock connected to the multiplier and the electrosurgical generator for setting units of time which are about a millisecond for thus providing feedback useful for immediate use in real time to the electrosurgical generator for regulating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads;

an integrator, within the automatic control circuit, joined to the multiplier and clock and responsive thereto, the integrator to calculate an energy supplied through the leads per each unit of time established by the clock based on an instantaneous power flow calculation of the multiplier, the integrator for calculating the energy applied over each unit of time during the operation of the electrosurgical generator during desiccation of tissue between the electrodes, and

a correlation circuit, within the automatic control circuit, coupled to the integrator to receive amount of energy calculated from the integrator and the reference signal in accord with the setting of the user control to which the correlation circuit is connected, the correlation circuit electrically connected to the electrosurgical generator to provide a feedback signal to indicate when the amount of energy calculated equals the user control setting for altering the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads and wherein the correlation circuit is a comparator to receive the energy calculations from the integrator and a reference signal in accord with the setting of the user control, the comparator to provide a feedback signal to indicate when the amount of energy calculated equals the user control setting for terminating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads by altering a drive circuit thereof so the supply of high frequency electrosurgical energy to the active and return leads is automatically adjusted.

14. An electrosurgical generator setting responsive to levels of tissue impedance between an active electrode and a return electrode wherein each electrode is electrically connected to the electrosurgical generator comprising:

an active lead and a return lead wherein each electrically connected to the generator to supply high frequency electrosurgical energy;

a user control, electrically connected to the electrosurgical generator, for a preset level of energy desired for electrosurgery and for setting a reference signal in the electrosurgical generator indicative of the preset energy level desired by the user,

an automatic control circuit, electrically connected to the electrosurgical generator;

a voltage sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the leads, the voltage sensing circuit capable of providing a signal of voltage level between the active and return leads;

a current sensing circuit, within the automatic control circuit, responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the return lead, the current sensing circuit capable of providing a signal of current level;

a multiplier, within the automatic control circuit, connected to the voltage and current sensing circuits to receive the signals from the voltage and current sensing circuits and to multiply those signals together for calculating power flow through the leads of the electrosurgical generator;

a clock, within the automatic control circuit, for establishing units of time during which power flow calculated by the multiplier is considered, the clock connected to the multiplier and the electrosurgical generator for setting units of time which are about a millisecond for thus providing feedback useful for immediate use in real time to the electrosurgical generator for regulating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads;

an integrator, within the automatic control circuit, joined to the multiplier and clock and responsive thereto, the integrator to calculate an energy supplied through the leads per each unit of time established by the clock based on an instantaneous power flow calculation of the multiplier, the integrator for calculating the energy applied over each unit of time during the operation of the electrosurgical generator during desiccation of tissue between the electrodes;

a correlation circuit, within the automatic control circuit, coupled to the integrator to receive amount of energy calculated from the integrator and the reference signal in accord with the setting of the user control to which the correlation circuit is connected, the correlation circuit electrically connected to the electrosurgical generator to provide a feedback signal to indicate when the amount of energy calculated equals the user control setting for altering the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads and wherein the correlation circuit is a comparator to receive the energy calculations from the integrator and a reference signal in accord with the setting of the user control, the comparator to provide a feedback signal to indicate when the amount of energy calculated equals the user control setting for terminating the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads by altering a drive circuit thereof so the supply of high frequency electrosurgical energy to the active and return leads is automatically adjusted; and

wherein the user control has two added adjusters one for setting a number of packets of energy and another for setting the preset level of energy delivered per packet.

15. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 14 wherein the adjuster for energy level per packet includes a potentiometer that provides a direct current voltage as the reference signal of energy level.

16. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 14 wherein a counter in the electrosurgical generator assesses the number of packets of energy delivered against the setting of the one adjuster of the number of packets as established by the user control with a second comparator.

17. The electrosurgical generator responsive to the level of tissue impedance between active and return electrodes of the electrosurgical generator of claim 16 wherein the counter in the electrosurgical generator assesses the number of packets of energy delivered against the setting of the adjuster of the number of packets as established by the user control with the second comparator and the total energy delivered is a function of multiple packet sequences containing pulses wherein the time between the pulses is controlled by the user control.

18. A method of automatically controlling an electrosurgical generator in response to the level of tissue impedance between active and return electrodes of the electrosurgical generator during tissue desiccation includes the steps of:

using an electrosurgical generator having an active lead and a return lead to supply high frequency electrosurgical energy in the form of at least one energy packet to an active electrode and a return electrode;

setting a user control on the electrosurgical generator at an amount of energy desired for electrosurgery;

setting a first adjuster to a total number of energy packets to be supplied to said active electrode and said return electrode;

setting a second adjuster to a time between delivery of energy packets;

providing a signal of voltage level between the active and return leads with a voltage sensing circuit responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the leads;

providing a signal of current level with a current sensing circuit responsive to high frequency electrosurgical energy supplied by the electrosurgical generator and flowing through the active or return lead;

calculating power flow through the leads of the electrosurgical generator with a multiplier receiving the signals from the voltage and current sensing circuits by multiplying those signals together;

establishing units of time with a clock during a time during which power flow calculated by the multiplier is considered;

calculating with an integrator an energy supplied through the leads per each unit of time established by the clock based on an instantaneous power calculation of the multiplier;

setting with the user control a reference signal indicative of the amount of energy desired by the user;

providing, with a correlation circuit connected to receive energy calculated from the integrator, the reference signal in accord with the setting of the user control, and a feedback signal to indicate when the energy calculation equals the user control setting, and

altering the electrosurgical generator supply of high frequency electrosurgical energy to the active and return leads in accord with the feedback signal.

19. An electrosurgical generator responsive to levels of tissue impedance comprising:

an active lead and a return lead wherein each lead is electrically coupled to said electrosurgical generator for supplying high frequency electrosurgical energy in the form of at least one energy packet;

a user control, electrically coupled to said electrosurgical generator, for setting a preset level of energy desired for electrosurgery and for setting a reference signal in said electrosurgical generator indicative of said preset energy level desired by a user, said user control comprising a first adjuster for setting a number of packets of energy and a second adjuster for setting a preset level of energy delivered per packet;

circuitry, electrically coupled to said active lead and said return lead, for calculating power flow through said active and return leads;

an integrator coupled to said circuitry for calculating an amount of energy supplied through said leads, per unit of time, based on said calculated power flow; and

,

a correlation circuit, coupled to said integrator to receive said calculation of an amount of energy from said integrator, and coupled to said user control to receive said reference signal, said correlation circuit providing a feedback signal to indicate when said calculation of an amount of energy equals said reference signal for terminating the supply high frequency electrosurgical energy to the active and return leads.