Control system and process for application of energy to airway walls and other mediums

• US 7,854,734 B2
• Filed: 07/17/2006
• Issued: 12/21/2010
• Est. Priority Date: 10/17/2000
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Asthmatx, Inc. (Boston Scientific Corporation)
• Inventors: Danek, Christopher J., Biggs, Michael, Stern, Roger A.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US11/458,074
• Publication Number:
  US 20060247726A1
• Time in Patent Office: 1,618 Days
• Field of Search: 606 32- 35, 606/41, 607101-102
• US Class Current: 606/34
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 2018/00541 Lung or bronchi
• CPC Class Codes: A61N 1/06 for high-frequency therapy
• CPC Class Codes: A61N 1/40 Applying electric fields by inductive or capacitive coupling microwave apparatus A61N5/00; Applying radio-frequency signals

Abstract

The present invention includes a system for delivering energy to an airway wall of a lung comprising an energy delivering apparatus and a PID controller having one or more variable gain factors which are rest after energy deliver has begun. The energy delivering apparatus may include a flexible elongated member and a distal expandable basket having at least one electrode for transferring energy to the airway wall and at least one temperature sensor for measuring temperature. The PID controller determines a new power set point base on an error between a preset temperature and the measured temperature. The algorithm can be P_i+1=P_i+G(αe_i+βe_i−1+γe_i−2) where α, β and γ are preset values and α is from 1 to 2; β is from −1 to −2; and γ is from −0.5 to 0-5. In another variation, the controller is configured to shut down if various measured parameters are exceeded such as, for example, energy, impedance, temperature, temperature differences, activation time and combinations thereof. Methods for treating a target medium using a PID algorithm are also provided.

Claims

1. A system for delivering energy to an airway wall of a lung comprising:

an energy delivering apparatus comprising a flexible elongated member and a distal expandable basket, said expandable basket having at least one electrode for transferring energy to said airway wall and at least one temperature sensor for measuring temperature (T_M) of said airway wall when energy is delivered to said airway wall; and

a PID controller for determining a new power set point (P_i+1) based on an error (e) between a preset temperature (T_S) and said measured temperature (T_M) wherein said PID controller applies an algorithm having a variable gain factor (G), wherein the controller includes instructions that cause the controller to terminate the power when the measured temperature TM decreases by about more then 10°

C. in a sample period.

2. The system of claim 1 wherein said controller is configured such that G is reset 0.1 to 2 seconds after energy delivery has begun.

3. The system of claim 2 wherein said controller is configured such that G is reset 0.5 seconds after energy delivery has begun.

4. The system of claim 3 wherein said controller is configured such that G is reset to 0.9 to 1.0 if a temperature rise in °

C. per Joule is less than or equal to 2.5.

5. The system of claim 3 wherein said controller is configured such that G is reset to 0.4 to 0.5 if a temperature rise in °

C. per Joule is between 2.5 to 5.0.

6. The system of claim 3 wherein said controller is configured such that G is reset to 0.2 to 0.3 if a temperature rise in °

C. per Joule is equal to 5.0 to 7.5.

7. The system of claim 3 wherein said controller is configured such that G is reset to 0.1 to 0.2 if a temperature rise in °

C. per Joule is greater than 7.5.

8. The system of claim 1 wherein said algorithm further includes a PID algorithm:

P_i+1=P_i+G(α

e_i+β

e<sub>i−

1</sub>+γ

e<sub>i−

2</sub>) where α

, β and

γ

are preset values.

9. The system of claim 8 wherein α

is from 1 to 2.

10. The system of claim 9 wherein β

is from −

1 to −

2.

11. The system of claim 10 wherein γ

is from −

0.5 to 0.5.

12. The system of claim 11 wherein α

, β

, γ

are 1.6, −

1.6, and 0.0 respectively.

13. The system of claim 1 wherein said controller is configured such that said energy delivery is tetininated if said energy delivered exceeds a maximum energy.

14. The system of claim 13 wherein said maximum energy is 120 joules.

15. The system of claim 1 wherein said controller is configured to deliver energy for an activation time period.

16. The system of claim 15 wherein said controller is configured such that the activation time period is up to 15 seconds.

17. The system of claim 16 wherein said controller is configured such that the activation time period is 8 to 12 seconds.

18. The system of claim 17 wherein said controller is configured such that the activation time period is 10 seconds.

19. The system of claim 1 wherein said controller is configured such that T_S is set at a value between 60 to 80°

C.

20. The system of claim 19 wherein T_S is set at 65°

C.

21. The system of claim 1 wherein said controller is configured to measure impedance and said energy delivery is terminated when said impedance drops below a preset impedance value.

22. The system of claim 21 wherein said preset impedance value is 40 to 60 ohms.

23. The system of claim 1 wherein said controller is configured to terminate said energy delivery if said T_M exceeds T_S by a pre-selected value.

24. The system of claim 23 wherein said pre-selected value is 10°

C.

25. The system of claim 23 wherein said pre-selected value is 15°

C.

26. The system of claim 23 wherein said pre-selected value is 20°

C.

27. The system of claim 1 wherein a nominal output power of the energy delivered is set at a value of at least 17 watts.

28. The system of claim 27 wherein said sampling period is set at a value of at least 0.5 seconds.

29. The system of claim 28 wherein said critical temperature difference is 2°

C.

30. The system of claim 1 further comprising terminating the energy delivery if the T_M averaged over a time window exceeds T_S by a fixed temperature difference.

31. The system of claim 30 wherein said fixed temperature difference is 5°

C.

32. The system of claim 31 wherein said time window is between 1 and 5 seconds.

33. The system of claim 32 wherein said time window is 2 seconds.

34. The system of claim 1 wherein the sample period is 1.0 seconds.

35. The system of claim 1 wherein the sample period is 0.2 seconds.

36. The system of claim 1 wherein the gain factor is initially equal to a value between 0.4 and 0.5.

37. The system of claim 1 wherein said PID controller applies an algorithm having a plurality of variable gain factors.

38. The system of claim 37 wherein said algorithm is P_i+1=+(G₁e_i+G₂e_i−

1+G₃e<sub>i−

2</sub>) where G₁, G₂ and G₃ are variable gain factors.

39. The system of claim 38 wherein said controller is configured such that said variable gain factors are reset 0.1 to 2 seconds after energy delivery has begun.

40. The system of claim 39 wherein said controller is configured such that said variable gain factors are reset 0.5 seconds after energy delivery has begun.

41. The system of claim 40 wherein said controller is configured such that G₁, G₂ and G₃ are reset to 0.90 to 2.00, −

0.90 to −

2.00 and 0.5 to −

0.5 respectively if a temperature rise in °

C. per Joule is less than or equal to 2.5.

42. The system of claim 40 wherein said controller is configured such that G₁, G₂ and G₃ are reset to 0.40 to 1.00, −

0.40 to −

1.00 and 0.25 to −

0.25 respectively if a temperature rise in °

C. per Joule is between 2.5 to 5.0.

43. The system of claim 40 wherein said controller is configured such that G₁, G₂ and G₃ are reset to 0.20 to 0.60, −

0.20 to −

0.60 and 0.15 to −

0.15 respectively if a temperature rise in °

C. per Joule is equal to 5.0 to 7.5.

44. The system of claim 40 wherein said controller is configured such that G₁, G₂ and G₃ are reset to 0.10 to 0.40, −

0.10 to −

0.40 and 0.10 to −

0.10 respectively if a temperature rise in °

C. per Joule is greater than 7.5.

45. The system of claim 38 wherein each of said variable gain factors is equal to a product of at least one preset value and at least one variable value.

46. The system of claim 1 wherein the energy delivery apparatus is configured to deliver an amount of power up to a maximum power.

47. The system of claim 46 wherein the maximum power is 10 to 40 watts.

48. The system of claim 47 wherein the maximum power is 15 to 20 watts.

49. A system for delivering energy to an airway wall of a lung comprising:

an energy delivering apparatus comprising a flexible elongated member and a distal expandable basket, said expandable basket having at least one electrode for transferring energy to said airway wall and at least one temperature sensor for measuring temperature (T_M) of said airway wall when energy is delivered to said airway wall; and

a PID controller for determining a new power set point (P_i+1) based on an error (e) between a preset temperature (T_S) and said measured temperature (T_M) wherein said PID controller applies an algorithm having a variable gain factor (G), wherein the controller includes instructions that cause the controller to terminate the power when the power exceeds 15-20 W and the temperature decreases by about more the 2°

C. over a sampling period of about 0.1 to 1.0 second.

50. The system of claim 49 wherein the controller includes instructions that cause the controller to terminate power when the power exceeds about 17 W.