Condition responsive gas flow adjustment in gas-assisted electrosurgery

• US 6,206,878 B1
• Filed: 05/07/1999
• Issued: 03/27/2001
• Est. Priority Date: 05/07/1999
• Status: Expired due to Term

• Current Assignee: Aspen Laboratories, Inc. (Jefferies Financial Group, Inc.)
• Original Assignee: Aspen Laboratories, Inc. (Jefferies Financial Group, Inc.)
• Inventors: Crenner, James C., Bishop, David K.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US09/307,293
• Time in Patent Office: 690 Days
• Field of Search: 606/37-42, 606/45-50, 219/121.51, 219/121.55
• US Class Current: 606/49
• CPC Class Codes: A61B 18/042 using additional gas becoming plasma

Abstract

A gas delivery apparatus used in gas-assisted electrocoagulation temporarily reduces a gas flow rate in a flowpath to an application which applies the flow of gas and electrical energy to the tissue during an arc initiation sequence. The reduced gas flow rate enhances the arc initiation capabilities and reduces the possibilities of embolism. After the arc initiation sequence is complete, the gas flow rate returns to a greater rate used during electrocoagulation. The back pressure in the flowpath and a user requested flow rate are control variables used to reduce the flow rate upon the occurrence of back pressure-related conditions and to increase the flow rate after the dissipation of those back pressure conditions.

Claims

1. A gas delivery apparatus for gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue in response to an electrocoagulation activation request, comprising:

a gas flow-controlling valve connected in the flowpath; and

a flow controller connected to the valve and responsive to the activation request to supply a control signal to the valve to set an initiation gas flow rate in the flowpath to more readily initiate the transfer of arcs from the applicator, the controller also supplying a control signal to the valve to set an electrocoagulation gas flow rate in the flowpath to conduct the arcs during electrocoagulation after initiation of the arc transfer, the initiation gas flow rate being less than the electrocoagulation gas flow rate.

2. A gas delivery apparatus as defined in claim 1 wherein the initiation gas flow rate occurs for a predetermined time duration after the occurrence of the activation request.

3. A gas delivery apparatus as defined in claim 1 wherein the initiation gas flow rate is set only if the electrocoagulation gas flow rate exceeds a predetermined value.

4. A gas delivery apparatus as defined in claim 1, further comprising:

a pressure sensor connected in the flowpath and connected to the controller to supply a signal related to pressure in the flowpath resulting from the gas flow in the flowpath; and

wherein;

the controller controls the valve to terminate the gas flow in the flowpath upon the pressure-related signal exceeding a predetermined pressure limit.

5. A gas delivery apparatus as defined in claim 4 wherein:

the controller controls the valve to set the initiation gas flow rate for a predetermined time after the occurrence of the activation request; and

the controller controls the valve to terminate the gas flow upon the pressure-related signal exceeding the predetermined pressure limit during the predetermined time of the initiation gas flow rate.

6. A gas delivery apparatus as defined in claim 5 wherein:

the pressure limit first aforesaid applies during initiation gas flow rates;

the controller also controls the valve to terminate the gas flow upon the pressure-related signal exceeding a second predetermined pressure limit which is different from the first predetermined pressure limit, the second predetermined pressure limit applying during electrocoagulation gas flow rate conditions; and

the controller controls the valve to terminate the gas flow upon the pressure-related signal exceeding the second predetermined pressure limit after the cessation of the initiation gas flow rate and during the electrocoagulation gas flow rate.

7. A gas delivery apparatus as defined in claim 5 wherein:

the controller also terminates the gas flow upon the pressure-related signal exceeding a second predetermined pressure limit which is different from that predetermined limit first aforesaid, the second predetermined pressure limit applying after expiration of the predetermined time during which the initiation gas flow rate occurs.

8. A gas delivery apparatus as defined in claim 1 further comprising:

a pressure sensor connected in the flowpath and connected to the controller to supply a signal related to pressure in the flowpath resulting from the gas flow in the flowpath; and

wherein;

the controller responds to the pressure-related signal to determine whether an occlusion condition is present in the flowpath.

9. A gas delivery apparatus as defined in claim 8 wherein:

the controller controls the valve to reduce the gas flow rate in the flowpath by a predetermined increment in response to the pressure-related signal indicating a partial occlusion condition in the flowpath.

10. A gas delivery apparatus as defined in claim 9 wherein:

the controller controls the valve to increase the gas flow rate in the flowpath in response to the pressure-related signal indicating a dissipation of the partial occlusion in the flowpath.

11. A gas delivery apparatus as defined in claim 1 further comprising:

a pressure sensor connected in the flowpath and connected to the controller to supply a signal related to pressure in the flowpath resulting from the gas flow in the flowpath; and

wherein;

the controller controls the valve to terminate the gas flow in the flowpath upon the pressure-related signal exceeding a predetermined alarm limit.

12. A gas delivery apparatus as defined in claim 1 further comprising:

a pressure sensor connected in the flowpath and connected to the flow controller to supply a signal related to pressure in the flowpath resulting from the gas flow in the flowpath; and

wherein;

the controller determines the type of applicator connected in the flowpath in response to the pressure-related signal.

13. A gas delivery apparatus as defined in claim 12 wherein:

the controller controls the valve to establish a maximum gas flow rate through the flowpath to the determined type of applicator in response to the pressure-related signal.

14. A gas delivery apparatus as defined in claim 1 further comprising:

a selector to establish a user requested electrocoagulation gas flow rate and to supply a signal to the controller related to the user requested electrocoagulation gas flow rate;

a sensor connected in the flowpath to measure a mass flow rate of gas in the flowpath and to supply a signal to the controller related to the mass flow rate; and

wherein;

the controller controls the valve in relation to a difference between the user requested gas flow rate signal and the mass flow rate-related signal.

15. A gas delivery apparatus for gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator in response to an electrocoagulation activation request and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising:

a gas flow-controlling valve connected in the flowpath;

a selector to establish a user requested electrocoagulation gas flow rate in the flowpath and to supply a signal related to the user requested electrocoagulation gas flow rate;

a pressure sensor connected in the flowpath and operative to supply a signal related to pressure in the flowpath resulting from the gas flow in the flowpath; and

a flow controller connected to the valve and receptive of the pressure-related signal and the user requested flow rate signal, the controller controlling the valve to reduce the gas flow rate in the flowpath from the electrocoagulation gas flow rate corresponding to the user requested flow rate upon the pressure-related signal indicating a pressure in the flowpath exceeding a predetermined limit.

16. A gas delivery apparatus as defined in claim 15 wherein:

the controller determines the type of applicator connected in the flowpath in response to the pressure-related signal.

17. A gas delivery apparatus as defined in claim 15 wherein:

the controller establishes a maximum gas flow rate to the applicator in response to the relationship of the pressure-related signal to one of either a predetermined maximum pressure limit or the user requested flow rate signal.

18. A gas delivery apparatus as defined in claim 17 wherein:

the controller controls the valve to terminate the flow of gas in the flowpath in response to the pressure-related signal exceeding the predetermined maximum pressure limit.

19. A gas delivery apparatus as defined in claim 18 in combination with an electrosurgical generator connected to deliver electrical energy to the applicator for ionizing the gas and transferring electrical energy in arcs, and wherein:

the controller is connected to the generator to control the generator to terminate the delivery of electrical energy in response to the termination of gas flow in the flowpath.

20. A gas delivery apparatus as defined in claim 18 in combination with an electrosurgical generator connected to deliver electrical energy to the applicator for ionizing the gas and transferring electrical energy in arcs, and wherein:

the controller is connected to the generator to control the generator to terminate the delivery or electrical energy in response to the pressure-related signal exceeding the predetermined maximum pressure limit.

21. A gas delivery apparatus as defined in claim 15 wherein:

the controller controls the valve to increase the gas flow rate in the flowpath to the gas flow rate corresponding to the user requested flow rate signal upon the pressure-related signal indicating that the pressure in the flowpath has decreased below the predetermined pressure limit.

22. A gas delivery apparatus as defined in claim 21 in combination with an electrosurgical generator connected to deliver electrical energy to the applicator for ionizing the gas and transferring electrical energy in arcs, and wherein:

the user requested flow rate signal is established in relation to a user requested power level for the electrosurgical generator.

23. A gas delivery apparatus as defined in claim 15 wherein:

the controller determines whether one of a gastrointestinal probe applicator or an endoscopic probe applicator is connected in the flowpath in response to the pressure-related signal; and

the controller controls the valve to establish predetermined maximum flow rates for the gastrointestinal probe applicator and for the endoscopic probe applicator, and the predetermined maximum flow rate for the gastrointestinal probe is less than the predetermined maximum flow rate for the endoscopic probe applicator.

24. A gas delivery apparatus as defined in claim 23 wherein:

the controller controls the valve to establish the maximum gas flow rate in the flowpath to the gastrointestinal probe applicator on the basis of the smaller one of the predetermined maximum flow rate for the gastrointestinal probe applicator or the gas flow rate corresponding to the user requested flow rate signal.

25. A gas delivery apparatus as defined in claim 24 wherein:

the controller controls the valve to reduce the gas flow rate in the flowpath to the gastrointestinal probe applicator by an incremental amount in response to the pressure-related signal exceeding a predetermined fold pressure limit which is related to gas flow rate in the flowpath immediately before the reduction in gas flow rate.

26. A gas delivery apparatus as defined in claim 25 wherein:

the controller controls the valve to terminate the flow of gas in the flowpath in response to the pressure-related signal exceeding a predetermined trip point pressure limit related to the gas flow rate in the flowpath immediately before the termination of the gas flow.

27. A gas delivery apparatus as defined in claim 25 wherein:

the controller controls the valve to increase the gas flow rate in the flowpath to the gastrointestinal probe applicator by an incremental amount in response to the pressure-related signal falling below an increase-inducing predetermined pressure limit related to the predetermined fold pressure limit.

28. A gas delivery apparatus as defined in claim 23 wherein:

the controller controls the valve to establish the maximum gas flow rate in the flowpath to the endoscopic probe applicator on the basis of the smaller one of the predetermined maximum flow rate for the endoscopic probe applicator or the gas flow rate corresponding to the user requested flow rate signal.

29. A gas delivery apparatus as defined in claim 28 wherein:

the controller controls the valve to terminate the flow of gas in the flowpath in response to the pressure-related signal exceeding a predetermined trip point pressure limit related to the gas flow rate in the flowpath immediately before the termination of the gas flow.

30. A gas delivery apparatus as defined in claim 28 wherein:

the controller controls the valve to increase the gas flow rate in the flowpath by an incremental amount to the endoscopic probe applicator in response to the pressure-related signal falling below an increase-inducing predetermined pressure limit related to a predetermined maximum pressure limit for the endoscopic probe applicator.

31. A gas delivery apparatus as defined in claim 15 in combination with an electrosurgical generator connected to deliver electrical energy to the applicator for ionizing the gas and transferring electrical energy in arcs, and wherein:

the user requested flow rate signal is established in relation to a user requested power level for the electrosurgical generator.

32. A gas delivery apparatus as defined in claim 31, wherein the applicator is an open surgery applicator.

33. A gas delivery apparatus as defined in claim 15 further comprising:

a gas flow sensor connected in the flowpath to supply a gas flow rate signal related to the amount of gas flowing in the flowpath; and

wherein;

the controller receives the gas flow rate signal and determines an actual gas flow rate in the flowpath;

the controller further determines whether the gas flow rate is within one of a plurality of predetermined different gas flow ranges;

the controller controls the valve to reduce the gas flow rate in the flowpath upon the pressure-related signal indicating a pressure in the flowpath which exceeds a predetermined limit for a predetermined gas flow range.

34. A method of gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising the steps of:

flowing gas in the flowpath to the applicator;

initially setting an initiation gas flow rate to the applicator;

transferring electrical energy in arcs to the tissue in the gas flowing from the applicator at the initiation gas flow rate; and

setting the gas flow rate to an electrocoagulation gas flow rate after the arcs have been transferred to the tissue and while continuing to transfer arcs in the gas flowing at the electrocoagulation gas flow rate, the electrocoagulation gas flow rate being greater than the initiation gas flow rate.

35. A method as defined in claim 34 further comprising the steps of:

maintaining the initiation gas flow rate for a predetermined time period after commencing the delivery of the initiation gas flow rate.

36. A method as defined in claim 34 further comprising the steps of:

sensing pressure in the flowpath; and

reducing the initiation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a predetermined initiation pressure limit while the gas flows at the initiation gas flow rate.

37. A method as defined in claim 36 further comprising the step of:

terminating the initiation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a second predetermined initiation pressure limit which is greater than the predetermined initiation pressure limit first aforesaid while the gas flows at the initiation gas flow rate.

38. A method as defined in claim 37 further comprising the step of:

reducing the electrocoagulation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a predetermined electrocoagulation pressure limit while the gas flows at the electrocoagulation gas flow rate.

39. A method as defined in claim 38 further comprising the step of:

terminating the electrocoagulation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a second predetermined electrocoagulation pressure limit which is greater than the predetermined electrocoagulation pressure limit first aforesaid while the gas flows at the initiation gas flow rate.

40. A method as defined in claim 34 further comprising the steps of:

sensing pressure in the flowpath; and

reducing the electrocoagulation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a predetermined electrocoagulation pressure limit while the gas flows at the electrocoagulation gas flow rate.

41. A method as defined in claim 40 further comprising the step of:

terminating the electrocoagulation gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a second predetermined electrocoagulation pressure limit which is greater than the predetermined electrocoagulation pressure limit first aforesaid while the gas flows at the initiation gas flow rate.

42. A method as defined in claim 34 further comprising the steps of:

requesting a value of the electrocoagulation gas flow rate;

determining whether the requested electrocoagulation gas flow rate exceeds a predetermined value; and

setting the initiation gas flow rate to the electrocoagulation gas flow rate if the requested electrocoagulation gas flow rate does not exceed the predetermined value.

43. A method as defined in claim 34 wherein the step of sensing pressure in the flowpath further comprises the step of:

sensing a pressure in the flowpath which relates to a back pressure resulting from the gas flow in the flowpath.

44. A method as defined in claim 43 further comprising the step of:

determining whether an occlusion condition is present in the flowpath based on the sensed pressure.

45. A method as defined in claim 44 further comprising the step of:

reducing the gas flow rate in the flowpath in response to the sensed pressure indicating a partial occlusion condition in the flowpath.

46. A method as defined in claim 44 further comprising the step of:

reducing the gas flow rate in the flowpath by a predetermined increment in response to the sensed pressure indicating a partial occlusion condition in the flowpath.

47. A method as defined in claim 44 further comprising the step of:

increasing the gas flow rate in the flowpath in response to the sensed pressure indicating a dissipation of the partial occlusion condition in the flowpath.

48. A method as defined in claim 44 further comprising the step of:

establishing a maximum gas flow rate for the applicator in response to the sensed pressure.

49. A method as defined in claim 43 further comprising the step of:

determining the type of applicator connected in the flowpath in response to the sensed pressure.

50. A method as defined in claim 49 further comprising the step of:

flowing gas at a maximum gas flow rate through the flowpath to the determined type of applicator in response to the pressure-related signal.

51. A method as defined in claim 34 further comprising the steps of:

requesting a value of the electrocoagulation gas flow rate;

measuring a mass flow rate of gas in the flowpath; and

varying the gas flow through the flowpath relative to any difference between the requested gas flow rate and the measured mass flow rate.

52. A method of gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising the steps of:

flowing gas through the flowpath;

sensing a pressure in the flowpath resulting from gas flow in the flowpath; and

reducing the gas flow rate in the flowpath without terminating the gas flow in the flowpath upon the sensed pressure exceeding a predetermined limit.

53. A method as defined in claim 52 further comprising the step of:

terminating the flow of gas in the flowpath in response to the sensed pressure exceeding a predetermined maximum pressure limit.

54. A method as defined in claim 53 further comprising the steps of:

delivering electrical energy to the applicator to ionize the gas and transfer electrical energy in arcs; and

terminating the delivery of electrical energy in response to the termination of gas flow in the flowpath.

55. A method as defined in claim 52 further comprising the steps of:

requesting a value of the electrocoagulation gas flow rate; and

establishing a maximum gas flow rate to the applicator in response to the relationship of the sensed pressure to one of either a predetermined maximum pressure or the requested electrocoagulation flow rate.

56. A method as defined in claim 52 comprising the steps of:

requesting a value of the electrocoagulation gas flow rate; and

increasing the gas flow rate in the flowpath to the gas flow rate corresponding to the requested flow rate value upon the sensed pressure decreasing below the predetermined limit.

57. A method as defined in claim 52 further comprising the steps of:

delivering electrical energy at a power level to ionize the gas and transfer electrical energy in arcs; and

setting the electrocoagulation gas flow rate in relation to the power level of the delivered electrical energy.

58. A method of gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising the steps of:

flowing gas through the flowpath;

sensing a pressure in the flowpath resulting from gas flow in the flowpath;

reducing the gas flow rate in the flowpath upon the sensed pressure exceeding a predetermined limit; and

determining the type of applicator connected in the flowpath from sensing the pressure in the flowpath.

59. A method of gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising the steps of:

flowing gas through the flowpath;

sensing a pressure in the flowpath resulting from gas flow in the flowpath;

reducing the gas flow rate in the flowpath upon the sensed pressure exceeding a predetermined limit;

determining whether one of a gastrointestinal probe applicator or an endoscopic probe applicator is connected in the flowpath by sensing the pressure; and

establishing predetermined maximum flow rates for the gastrointestinal probe applicator and for the endoscopic probe applicator, the predetermined maximum flow rate for the gastrointestinal probe being less than a predetermined maximum flow rate for the endoscopic probe applicator.

60. A method as defined in claim 59 further comprising the steps of:

requesting a value of the electrocoagulation gas flow rate; and

establishing the maximum gas flow rate in the flowpath to the gastrointestinal probe applicator on the basis of the smaller one of a predetermined maximum flow rate for the gastrointestinal probe applicator or the requested gas flow rate.

61. A method of gas-assisted electrocoagulation in which a flow of gas is supplied in a flowpath to an applicator and the gas is ionized at the applicator to transfer electrical energy in arcs to coagulate bleeding from tissue, comprising the steps of:

flowing gas through the flowpath;

sensing a pressure in the flowpath resulting from gas flow in the flowpath;

reducing the gas flow rate in the flowpath upon the sensed pressure exceeding a predetermined limit;

measuring the gas flow rate in the flowpath;

determining one of a plurality of predetermined different gas flow ranges in which the measured gas flow rate falls; and

reducing the gas flow rate in the flowpath upon the sensed pressure in the flowpath exceeding a predetermined limit for the predetermined gas flow range within which the measured gas flow rate falls.