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

• US 7,837,679 B2
• Filed: 07/17/2006
• Issued: 11/23/2010
• Est. Priority Date: 10/17/2000
• Status: Expired due to Term

• 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:
  US11/458,084
• Publication Number:
  US 20060247727A1
• Time in Patent Office: 1,590 Days
• Field of Search: 606 32- 35, 606/41, 606 48- 50, 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 method for treating a lung by transferring energy from an active region of an energy delivery apparatus to an airway wall of said lung, said energy delivery apparatus having a flexible elongate body and a distal section and said active region being located in said distal section, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said airway wall, said method comprising:

setting a preset temperature (T_s);

determining a power set point (P_i) to deliver energy from said active region to said target medium;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁) based on an error (e) between said preset temperature (T_s) and said measured temperature (T_M) using a PID algorithm; and

terminating said energy delivery when the temperature does not rise a predetermined amount in a specified period of time.

2. The process of claim 1 comprising terminating said energy delivery if said energy delivered exceeds a maximum energy.

3. The process of claim 2 wherein said maximum energy is 120joules.

4. The process of claim 1 further comprising measuring impedance and terminating said energy delivery when said impedance, drops below a preset impedance value.

5. The process of claim 4 wherein said preset impedance value is from 40 to 60 ohms.

6. The process of claim 1 comprising terminating said energy delivery if said T_M exceeds T_s by a pre-selected value.

7. The process of claim 6 wherein said pre-selected value is 10°

C.

8. The process of claim 6 wherein said pre-selected value is 15°

C.

9. The process of claim 6 wherein said pre-selected value is 20°

C.

10. The process of claim 1 wherein said delivering energy to a target medium is performed by delivering energy to an airway wall of a lung in vivo.

11. The process of claim 1 wherein the power is terminated when the temperature does not rise by more than about 10°

C. in about 3 seconds.

12. The process of claim 1 wherein the power is terminated when the temperature does not rise by more than about 10°

C. in about 1 second.

13. A process for transferring energy to a target medium using an energy delivery apparatus, said energy delivery apparatus having a flexible elongate body and a distal section wherein said distal section includes an expandable basket with at least one active region for transferring energy to said target medium, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said target medium, said process comprising:

setting a preset temperature (T_s);

determining a power set point (P_i) to deliver energy from said active region to said target medium;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁) based on an error (e) between said preset temperature (T_s) and said measured temperature (T_M) using an algorithm having a variable gain factor, wherein said algorithm is;

P_{i +1}=P_i+G(α

e_i+β

e_i-1+γ

e_i-2) where α

, β and

γ

are preset values, and wherein at least one of α

, β and

γ

is from −

0.5 to 0.5.

14. The process of claim 13 wherein the algorithm further includes a gain factor (G).

15. The process of claim 14 comprising resetting G 0.1 to 2seconds after energy delivery has begun.

16. The process of claim 15 comprising resetting G 0.5 seconds after energy delivery has begun.

17. The process of claim 16 comprising resetting G to 0.9 to 1.0 if a temperature rise in °

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

18. The process of claim 16 comprising resetting G to 0.4 to 0.5 if a temperature rise in °

C. per Joule is between 2.5 to 5.0.

19. The process of claim 16 comprising resetting G to 0.2 to 0.3 if a temperature rise in °

C. per Joule is equal to 5.0 to 7.5.

20. The process of claim 16 comprising resetting G to 0.1 to 0.2 if a temperature rise in °

C. per Joule is greater than 7.5.

21. The process of claim 13 comprising setting α

between 1 and 2.

22. The process of claim 21 comprising setting β

between −

1 to −

2.

23. The process of claim 13 comprising setting α

, β

, γ

to 1.6, −

1.6, and 0.0 respectively.

24. The process of claim 13 wherein energy is delivered for an activation period.

25. The process of claim 24 wherein said activation period up to 15seconds.

26. The process of claim 25 wherein said activation period is 8 to 12 seconds.

27. The process of claim 26 wherein said activation period is 10seconds.

28. The process of claim 13 comprising setting T_s at a value between 60 to 80°

C.

29. The process of claim 28 comprising setting T_s at 65°

C.

30. The process of claim 13 wherein said delivering energy to a target medium is performed by delivering energy to an airway wall of an excised lung.

31. The process of claim 13 wherein said delivering energy to a target medium is performed by delivering energy to a sponge or towel.

32. The process of claim 13 wherein the energy delivery apparatus is configured to deliver an amount of power up to a maximum power.

33. The process of claim 32 wherein the maximum power is 10 to 40 watts.

34. The process of claim 33 wherein the maximum power is 15 to 20 watts.

35. A process for transferring energy to a target medium using an energy delivery apparatus, said energy delivery apparatus having a flexible elongate body and a distal section wherein said distal section includes an expandable basket with at least one active region for transferring energy to said target medium, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said target medium, said process comprising:

setting a preset (T_s);

determining a power set point (P_i) to deliver energy from said active region to said target medium;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁ )based on an error (e) between said preset temperature (T_s) and said measured temperature(T_M) using an algorithm having a variable gain factor; and

terminating said energy delivery if an output power is greater or equal to a nominal output power and said T_M drops by a critical temperature difference within a sampling period.

36. The process of claim 35 wherein said nominal output power is set at a value of at least 17 watts.

37. The process of claim 36 wherein said sampling period is set at a value of at least 0.5 seconds.

38. The process of claim 37 wherein said critical temperature difference is 2°

C.

39. A process for transferring energy to a target medium using an energy delivery apparatus, said energy delivery apparatus having a flexible elongate body and a distal section wherein said distal section includes an expandable basket with at least one active region for transferring energy to said target medium, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said target medium, said process comprising:

setting a preset(T_s);

determining a power set point (P_i)to deliver energy from said active region to said target medium;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁)based on an error (e) between said preset temperature (T_S) and said measured temperature (T_M)using an algorithm having a variable gain factor; and

terminating said energy delivery if said T_M averaged over a time window exceeds T_S by a fixed temperature difference.

40. The process of claim 39 wherein said fixed temperature difference is a value between 1 and 10°

C.

41. The process of claim 40 wherein said fixed temperature difference is 5°

C.

42. The process of claim 41 wherein said time window is between 1and 5 seconds.

43. The process of claim 42 wherein said time window is 2seconds.

44. A process for transferring energy to a target medium using an energy delivery apparatus, said energy delivery apparatus having a flexible elongate body and a distal section wherein said distal section includes an expandable basket with at least one active region for transferring energy to said target medium, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said target medium, said process comprising:

setting temperature (T_s);

determining a power set point (P_i) to deliver energy from said active region to said target medium;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁) based on an error (e) between said preset temperature (T_s) and said measured temperature (T_M) using an algorithm having a variable gain factor; and

wherein said algorithm is P_i+1=P_i+(G₁e_i+G₂e_i-1+G₃e_i-2) where G₁, G₂ and G₃ are variable gain factors.

45. The process of claim 44 wherein said controller is configured such that said variable gain factors are reset 0.1 to 2 seconds after energy delivery has begun.

46. The process of claim 45 wherein said controller is configured such that said variable gain factors are reset 0.5 seconds after energy delivery has begun.

47. The process of claim 46 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 0.50 to −

0.50respectively if a temperature rise in °

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

48. The process of claim 46 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 −

0.25respectively if a temperature rise in °

C. per Joule is between 2.5 to 5.0.

49. The process of claim 46 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 −

0.15respectively if a temperature rise in °

C. per Joule is equal to 5.0 to 7.5.

50. The process of claim 46 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 −

0.10respectively if a temperature rise in °

C. per Joule is greater than 7.5.

51. The process of claim 46 wherein each of said variable gain factors is equal to a product of at least one preset value and at least one variable value.

52. A method for treating a lung by transferring energy from an active region of an energy delivery apparatus to an airway wall of said lung, said energy delivery apparatus having a flexible elongate body and a distal section and said active region being located in said distal section, said energy delivery apparatus further having a temperature sensor located in said distal section for measuring a temperature (T_M) of said airway wall, said method comprising:

setting a preset temperature (T_s);

determining a power set point (P_i) to deliver energy from said active region to said target medium;

delivering energy from the energy delivery apparatus to the airway wall during an energy delivery phase;

measuring said T_M using said temperature sensor;

determining a new power set point (P_i+₁) based on an error (e) between said preset temperature (T_s) and said measured temperature (T_M) using a PID algorithm; and

terminating said energy delivery when the temperature ramp rate is not within a predetermined range at a selected portion of the energy delivery phase.

53. The method of claim 52 wherein the temperature ramp rate is 8-15°

C. for the first 2-5 seconds of the energy delivery phase.