Staged impedance values to control thermal margins in electrosurgical systems

Patent metadata

Field	Value
Publication number	US-12303183-B2
Application number	US-202016874486-A
Country	US
Kind code	B2
Filing date	May 14, 2020
Priority date	May 9, 2019
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

Apparatus and associated methods relate to controlling electrical power of an electrotherapeutic signal that is provided to a biological tissue engaged by an electrosurgical instrument during a medical procedure. Electrical power—a product of a voltage difference across and an electrical current conducted by the engaged biological tissue—is controlled according to a therapeutic schedule. The electrotherapeutic schedule can be reduced or terminated in response to a termination criterion being met. In some examples, the termination criterion is a current characteristic, such as, for example, a decrease in current conducted by the engaged biological tissue. In some examples, the termination criterion is a biological tissue resistance characteristic, such as, for example, an increase in the biological tissue resistance that exceeds a predetermined delta resistance value.

First claim

The invention claimed is:

1. A surgical system comprising:
a control circuit; and
an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to couple to an electrosurgical device with at least one electrode,
wherein the control circuit is configured to:
count and deliver a pulse of a sequence of electrosurgical energy pulses to biological tissue in communication with the at least one electrode;
for the delivered pulse of the sequence of electrosurgical energy pulses:
compare a parameter to only a first threshold value; and
adjust, based on a pulse number of the delivered pulse in the sequence, the first threshold value to a second threshold value;

count and deliver a subsequent pulse of the sequence of electrosurgical energy pulses; and
for the delivered subsequent pulse:
compare the parameter to only the second threshold value; and
adjust, based on the pulse number of the delivered subsequent pulse in the sequence, the second threshold to a third threshold value.

2. The surgical system of claim 1 , wherein the parameter is selected from the group consisting of: an impedance of the biological tissue, a change in impedance of the biological tissue, a rate of change of the impedance of the biological tissue, a change in a phase angle, a change in a current of the delivered pulse, and a change in an output voltage of the delivered pulse.

3. The surgical system of claim 1 , wherein the control circuit is configured to:
retrieve data representing the first threshold value or the second threshold value from a memory device.

4. The surgical system of claim 1 , wherein the control circuit is configured to:
compare a first measured parameter to a second measured parameter, and
wherein the control circuit configured to adjust, based on the pulse number of the delivered pulse, the first threshold value is configured to:
adjust the threshold value based on a difference between the first measured parameter and the second measured parameter.

5. The surgical system of claim 1 , wherein the control circuit is configured to:
compare a first measured parameter to a second measured parameter, and
wherein the control circuit configured to adjust, based on the pulse number of the delivered pulse, the threshold value is configured to:
adjust the threshold value based on the first measured parameter being greater than the second measured parameter.

6. The surgical system of claim 1 , wherein the control circuit is configured to:
compare a first measured parameter to a second measured parameter, and
wherein the control circuit configured to adjust, based on the pulse number of the delivered pulse, the first threshold value is configured to:
adjust the first threshold value based on the first measured parameter being less than the second measured parameter.

7. The surgical system of claim 1 , wherein the control circuit is configured to:
determine a rate of change between a first measured parameter and a second measured parameter, and
wherein the control circuit is configured to adjust, based on the pulse number of the delivered pulse, the first threshold value is configured to:
adjust the first threshold value based on the rate of change between the first measured parameter and a second measured parameter.

8. The surgical system of claim 1 , wherein the control circuit is configured to:
adjust the first threshold value based on the parameter.

9. The surgical system of claim 1 , wherein the control circuit is configured to:
reduce the delivery of the sequence of electrosurgical energy pulses when a measured representation of impedance meets or exceeds an endpoint value.

10. A surgical system comprising:
a control circuit; and
an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to couple to an electrosurgical device having two jaws with corresponding electrodes,
wherein the control circuit is configured to:
count and deliver a pulse of a sequence of electrosurgical energy pulses to biological tissue in electrical communication with two electrodes of the electrosurgical device;
compare a first measured representation of impedance of the biological tissue to only a first threshold value;
reduce delivery of the pulse when the first measured representation of impedance meets or exceeds the first threshold value;
increase, based on a pulse number of the delivered pulse in the sequence, the first threshold value to a second threshold value;
count and deliver a subsequent pulse of the sequence to the tissue;
compare a second measured representation of impedance of the tissue to the second threshold value; and
reduce delivery of the delivered subsequent pulse when the second measured representation of impedance meets or exceeds the second threshold value.

11. The surgical system of claim 10 , wherein the control circuit is configured to:
retrieve data representing the first and second threshold values from a memory device.

12. The surgical system of claim 10 , wherein the control circuit is configured to:
compare the first measured representation of impedance to the second measured representation of impedance; and
determine the second threshold value based on a difference between the first measured representation of impedance and the second measured representation of impedance.

13. The surgical system of claim 10 , wherein the control circuit is configured to:
compare the first measured representation of impedance to the second measured representation of impedance; and
determine the second threshold value based on the first measured representation of impedance being greater than the second measured representation of impedance.

14. The surgical system of claim 10 , wherein the control circuit is configured to:
compare the first measured representation of impedance to the second measured representation of impedance; and
determine the second threshold value based on the first measured representation of impedance being less than the second measured representation of impedance.

15. The surgical system of claim 10 , wherein the control circuit is configured to:
determine a rate of change between the first measured representation of impedance and the second measured representation of impedance; and
determine the second threshold value based on the rate of change.

16. The surgical system of claim 10 , wherein the control circuit is configured to:
determine the second threshold value based on the first measured representation of impedance.

17. A method of delivering electrical energy to an electrosurgical device, the method comprising:
counting and delivering a pulse of a sequence of electrosurgical energy pulses to biological tissue in electrical communication with two electrodes of the electrosurgical device;
for the delivered pulse of the sequence of electrosurgical energy pulses:
comparing a parameter to only a first threshold value;
adjusting, based on a pulse number of the delivered pulse in the sequence, the first threshold value to a second threshold value; and
counting and delivering a subsequent pulse of the sequence of electrosurgical energy pulses; and

for the delivered subsequent pulse:
comparing the parameter to only the second threshold value; and
adjusting, based on the pulse number of the delivered subsequent pulse in the sequence, the second threshold to a third threshold value.

Assignees

• Gyrus Acmi Inc

Inventors

• Batchelor Kester Julian
• La Anh Tri
• Williams Wayne

Classifications

• A61B2018/1467

  using more than two electrodes on a single probe · CPC title

• A61B2018/00767

  Voltage · CPC title

• A61B2018/00714

  Temperature · CPC title

• A61B2017/00154

  pulsed · CPC title

• A61B18/1442

  Probes having pivoting end effectors, e.g. forceps · CPC title