Controlling impedance rise in electrosurgical medical devices

• US 9,737,355 B2
• Filed: 03/31/2014
• Issued: 08/22/2017
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Ethicon, LLC (Johnson & Johnson)
• Inventors: Yates, David C., Messerly, Jeffrey D., Davison, Mark A.
• Primary Examiner(s): Giuliani, Thomas
• Application Number:
  US14/230,349
• Publication Number:
  US 20150272657A1
• Time in Patent Office: 1,240 Days
• Field of Search: 606 34, 606 37, 606 41, 606 42, 606 50- 52
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/1445 at the distal end of a shaft, e.g. forceps or scissors at the end of a rigid rod
• CPC Class Codes: A61B 18/1447 wherein sliding surfaces cause opening/closing of the end effectors
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 2018/00589 Coagulation
• CPC Class Codes: A61B 2018/00595 Cauterization
• CPC Class Codes: A61B 2018/0063 Sealing
• CPC Class Codes: A61B 2018/00672 lower
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00767 Voltage
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00892 Voltage
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/1455 having a moving blade for cutting tissue grasped by the jaws

Abstract

Various embodiments are directed to electrosurgical systems for providing an electrosurgical signal to a patient. A control circuit may, for a first application period, apply the electrosurgical signal to first and second electrodes according to a first mode. In the first mode, the control circuit may limit the electrosurgical signal to a first maximum power when the impedance between the first and second electrodes exceeds a first mode threshold. The control circuit may also, for a second application period after the first application period, apply the electrosurgical signal according to a second mode. In the second mode, the control circuit may limit the electrosurgical signal to a second mode maximum power when the impedance between the first and second electrodes exceeds a second mode threshold. The second maximum power may be greater than the first maximum power.

Claims

1. An electrosurgical system for providing an electrosurgical signal to a patient, the system comprising:

a control circuit programmed to;

for a first application period during a coagulation cycle, apply the electrosurgical signal to first and second electrodes according to a first mode, wherein in the first mode, the control circuit is configured to;

limit the electrosurgical signal to a first first-mode maximum power when an impedance between the first and second electrodes is less than a first mode threshold; and

limit the electrosurgical signal to a second first-mode maximum power when the impedance between the first and second electrodes exceeds the first mode threshold, wherein the first first-mode maximum power is greater than the second first-mode maximum power; and

for a second application period after the first application period during the coagulation cycle, apply the electrosurgical signal according to a second mode, wherein in the second mode, the control circuit is configured to;

limit the electrosurgical signal to a first second-mode maximum power when the impedance between the first and second electrodes is less than a second mode threshold; and

limit the electrosurgical signal to a second second-mode maximum power when the impedance between the first and second electrodes exceeds the second mode threshold, wherein the first second-mode maximum power is greater than the second second-mode maximum power,

wherein the second second-mode maximum power is greater than the second first-mode maximum power.

2. The electrosurgical system of claim 1, wherein the first mode threshold is less than the second mode threshold.

3. The electrosurgical system of claim 1, wherein the control circuit is further programmed to:

for a third application period after the second application period during the coagulation cycle, apply the electrosurgical signal according to a third mode, wherein in the third mode, the control circuit is configured to;

limit the electrosurgical signal to a first third-mode maximum power when the impedance between the first and second electrodes is less than a third mode threshold; and

limit the electrosurgical signal to a second third-mode maximum power when the impedance between the first and second electrodes exceeds the third mode threshold.

4. The electrosurgical system of claim 3, wherein in the third mode, the control circuit is configured to limit the electrosurgical signal to the second third-mode maximum power when the impedance between the first and second electrodes exceeds the third mode threshold during an application period of a first sub-mode, and wherein the control circuit is further programmed to:

for a fourth application period after the third application period during the coagulation cycle, apply the electrosurgical signal according to a second sub-mode, wherein in the second sub-mode, the control circuit is configured to;

limit the electrosurgical signal to a first second-sub-mode maximum power when the impedance between the first and second electrodes is less than the third mode threshold; and

limit the electrosurgical signal to a second second-sub-mode maximum power when the impedance between the first and second electrodes exceeds the third mode threshold, wherein the second second-sub-mode maximum power is greater than the second third-mode maximum power.

5. The electrosurgical system of claim 4, wherein the control circuit is further programmed to:

for a fifth application period after the fourth application period during the coagulation cycle, apply the electrosurgical signal according to a third sub-mode, wherein in the third sub-mode, the control circuit is configured to limit the electrosurgical signal to a third-sub-mode maximum power when the impedance between the first and second electrodes exceeds the third mode threshold, wherein the third-sub-mode maximum power is greater than the second second-sub-mode maximum power.

6. The electrosurgical system of claim 3, wherein the control circuit is programmed to continue the third application period until the impedance between the first and second electrodes reaches a terminal threshold.

7. The electrosurgical system of claim 1, wherein the control circuit is configured to limit the electrosurgical signal to the second first-mode maximum power by limiting the electrosurgical signal to a first maximum voltage.

8. The electrosurgical system of claim 1, wherein in the first mode, the control circuit is also configured to limit the electrosurgical signal to a third first-mode maximum power when the impedance between the first and second electrodes exceeds a second first-mode threshold.

9. The electrosurgical system of claim 1, wherein the control circuit is further programmed to apply the electrosurgical signal during the first mode as a plurality of pulses.

10. The electrosurgical system of claim 1, wherein the control circuit is further programmed to:

after the first and second application periods, determine whether a new tissue bite has been initiated; and

upon determining that a new tissue bite has been initiated, apply the electrosurgical signal to the first and second electrodes according to the first mode.

11. The electrosurgical system of claim 1, wherein the second application period is longer than the first application period.

12. The electrosurgical system of claim 11, wherein the first application period is about 1.4 seconds and the second application period is about 4 to 5.4 seconds.