Energy delivery algorithm impedance trend adaptation

• US 8,162,932 B2
• Filed: 01/12/2009
• Issued: 04/24/2012
• Est. Priority Date: 01/12/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Tyco Healthcare Group LP (Medtronic Plc)
• Inventors: Podhajsky, Ronald J., Heckel, Donald W.
• Primary Examiner(s): BOUCHELLE, LAURA A
• Application Number:
  US12/351,960
• Publication Number:
  US 20100179534A1
• Time in Patent Office: 1,198 Days
• Field of Search: 607/96, 607/98, 607/99, 606/32, 606/34, 606/38, 606/41
• US Class Current: 606/38
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance

Abstract

A method for controlling an electrosurgical generator configured to apply energy to tissue as a function of a detected tissue property is contemplated by the present disclosure. The method includes the step of applying energy to the tissue in a first state, wherein the first state is configured to adjust the power output of the generator to continuously achieve peak tissue conductance as a function of the detected tissue property. The method also includes the step of monitoring a trend of the at least one detected tissue property indicative of a bubble field formation during a second state, which is running concurrently with the first state. The second state is configured to interrupt the bubble field to collapse the bubble field based on the trend of the at least one detected tissue property.

Claims

1. A method for controlling an electrosurgical generator configured to apply energy to tissue as a function of at least one detected tissue property, comprising the steps of:

applying energy to the tissue in a first state, wherein the first state is configured to adjust the power output of the generator to continuously achieve peak tissue conductance as a function of the at least one detected tissue property;

monitoring a trend of the at least one detected tissue property indicative of a bubble field formation during a second state, which is running concurrently with the first state, wherein the second state is configured to interrupt the bubble field to collapse the bubble field based on the trend of the at least one detected tissue property; and

comparing a calculated trend of the at least one detected tissue property to a plurality of predetermined impedance trends to determine a degree of bubble field formation.

2. The method according to claim 1, wherein the monitoring step further includes the step of:

calculating the trend of the at least one detected tissue property as a function of an average impedance or a change in impedance and a predetermined time period.

3. The method according to claim 1, wherein the monitoring step further includes the step of:

calculating the trend of the at least one detected tissue property as a function of a rate of change of impedance.

4. The method according to claim 1, further comprising the step of:

selecting at least one energy adjustment from a plurality of energy adjustments based on the comparison of the comparing step, each of the plurality of energy adjustments associated with each of the plurality of predetermined impedance trends.

5. The method according to claim 4, further comprising the step of:

performing the selected energy adjustment to adjust the energy being applied to the tissue, wherein the at least one energy adjustment is configured to interrupt the bubble field.

6. The method according to claim 1, wherein the applying energy step further comprising the steps of:

activating an electrosurgical generator to produce an electrosurgical waveform;

increasing power of the electrosurgical waveform during a first sample window;

determining a direction of change in a first average impedance during the first sample window in response to the increase in power of the electrosurgical waveform;

performing a first adjustment of power of the electrosurgical waveform in response to the direction of change in the first average impedance during a subsequent sample window;

determining a direction of change in a subsequent average impedance during the subsequent sample window in response to the first adjustment of power; and

performing a subsequent adjustment of power of the electrosurgical waveform in response to the direction of change in the subsequent average impedance, wherein the subsequent adjustment of power is reverse to that of the first adjustment of power when the direction of change in the first and subsequent average impedances is the same.

7. A method according to claim 6, wherein the step of adjusting power further comprises the steps of:

increasing the power of the electrosurgical waveform in response to a decrease in the first average impedance curve; and

decreasing the power of the electro surgical waveform in response to an increase in the average impedance.

8. A method according to claim 6, wherein the step of performing a subsequent adjustment of power further comprises the steps of:

decreasing the power of the electrosurgical waveform in response to a decrease in the first average impedance; and

increasing the power of the electrosurgical waveform in response to an increase in the average impedance.

9. A method according to claim 6, wherein after the step of performing a subsequent adjustment of power, the method further comprises the steps of:

continuously measuring peak impedance during a third sample window; and

comparing the peak impedance to a predetermined threshold change in impedance to determine a rapid rise in impedance.

10. A method according to claim 6, wherein after the step of performing a subsequent adjustment of power, the method further comprises the steps of:

determining a third average impedance during a third sample window;

determining a fourth average impedance during a fourth sample window; and

applying the electrosurgical waveform for a fifth sample window if the third and fourth average impedance are substantially equal.

11. A control system for use with an electrosurgical generator comprising:

a memory configured to store at least two states implemented as executable instructions, the at least two states configured for controlling energy applied to tissue, the memory further configured to store a plurality of predetermined impedance trends; and

a controller configured to signal the electrosurgical generator to apply energy to the tissue in a first state, during which the controller adjusts the power output of the electrosurgical generator to continuously achieve peak tissue conductance as a function of the at least one detected tissue property, the controller being further configured to monitor a trend of the at least one detected tissue property indicative of a bubble field formation during a second state, which is running concurrently with the first state, wherein during the second state the controller is configured to interrupt the bubble field to collapse the bubble field based on the trend of the at least one detected tissue property, wherein the controller is further configured to compare the calculated trend of the at least one detected tissue property to the plurality of predetermined impedance trends to determine a degree of bubble field formation.

12. The system according to claim 11, wherein the controller is further configured to calculate the trend of the at least one detected tissue property as a function of an average impedance or a change in impedance and a predetermined time period.

13. The system according to claim 11, wherein the controller is further configured to calculate the trend of the at least one detected tissue property as a function of a rate of change of impedance.

14. The system according to claim 11, wherein the controller is further configured to select at least one energy adjustment from a plurality of energy adjustments based on the comparison of the calculated trend, each of the plurality of energy adjustments associated with each of the plurality of predetermined impedance trends.

15. The system according to claim 14, wherein the controller is further configured to signal the selected energy adjustment to the electrosurgical generator to adjust the energy being applied to the tissue, wherein the at least one energy adjustment is configured to interrupt the bubble field.

16. A method for controlling energy applied by an electrosurgical generator to tissue as a function of at least one detected tissue property, comprising the steps of:

applying energy to the tissue in a first state, wherein the first state is configured to adjust the power output of the generator to continuously achieve peak tissue conductance as a function of the at least one detected tissue property; and

calculating a trend of the at least one detected tissue property indicative of a bubble field formation during a second state, wherein the second state is running concurrently with the first state and is configured to compare the calculated trend of the at least one detected tissue property to a plurality of predetermined impedance trends to determine a degree of bubble field formation, further wherein the second state is configured to interrupt the bubble field based on the comparison of the calculated trend of the at least one detected tissue property with the plurality of predetermined impedance trends.

17. The method according to claim 16, wherein the monitoring step further includes the step of:

calculating the trend of the at least one detected tissue property as a function of an average impedance or a change in impedance and a predetermined time period.

18. The method according to claim 16, wherein the monitoring step further includes the step of:

calculating the trend of the at least one detected tissue property as a function of a rate of change of impedance.