Endoscopic instrument with auto-regulating heater and method of using same

• US 5,593,406 A
• Filed: 01/14/1994
• Issued: 01/14/1997
• Est. Priority Date: 05/01/1992
• Status: Expired due to Fees

• Current Assignee: Hemostatic Surgery Corporation
• Original Assignee: Hemostatic Surgery Corporation
• Inventors: Manlove, Anthony J., Eggers, Philip E.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/182,528
• Time in Patent Office: 1,096 Days
• Field of Search: 606/28-34, 606/37-42, 606/45-52, 219/10.75
• US Class Current: 606/29
• CPC Class Codes: A61B 17/00234 for minimally invasive surgery A61B17/0218, A61B17/0469, A61B17/12013, A61B17/1285, A61B17/29, A61B17/320016 take precedence
• CPC Class Codes: A61B 18/082 Probes or electrodes therefor
• CPC Class Codes: A61B 18/10 Power sources therefor
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 18/1482 having a long rigid shaft for accessing the inner body transcutaneously in minimal invasive surgery, e.g. laparoscopy
• CPC Class Codes: A61B 2018/00107 Coatings on the energy applicator
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/126 bipolar
• CPC Class Codes: A61B 2218/002 Irrigation
• CPC Class Codes: A61B 2218/007 Aspiration

Abstract

An instrument for use in endoscopic surgery is provided. The instrument has a heating element with a working surface for providing hemostasis at an auto-regulated temperature. The working surface may include a tapered edge for providing thermally-enhanced cutting and a non-stick coating for operating the instrument at low auto-regulation temperatures. A process for making the instrument is also provided. Additionally, a method of performing endoscopic surgery on a patient'"'"'s internal tissue is also provided.

Claims

1. An instrument for use in endoscopic surgery comprising:

an elongated shaft having a proximal end and a distal end;

a working end connected to the distal end of the elongated shaft, the working end having a working surface for contacting tissue and a cross-section extending perpendicularly to the working surface, the working end integrally formed of a heating element, the working surface maintained at an auto-regulated temperature by conducting a current throughout the cross-section of the working end, the heating element comprising a material having a skin depth extending substantially throughout the cross-section of the working end responsive to the temperature of the heating element and that decreases as the temperature of the element falls below the auto-regulated temperature, the working end including a U-shaped portion having first and second legs and an electrically insulative gap located between the first and second legs;

first and second electrode leads connected to the proximal end of the elongated shaft; and

means for connecting the first and second electrode leads to the working end.

2. An instrument as defined in claim 1 wherein the material of said heating element further comprises a material that exhibits a Curie transition in permeability.

3. An instrument as defined in claim 2 wherein the material further comprises a ferromagnetic material.

4. An instrument as defined in claim 3 wherein the material further comprises an alloy of iron and nickel, wherein the alloy further comprises nickel having a concentration in the range of approximately 35 percent to approximately 55 percent by weight.

5. An instrument as defined in claim 1 wherein the working surface further comprises a tapered edge for thermally-enhanced cutting of tissue at a temperature in the range of the auto-regulated temperature, wherein the tapered edge defines an apex having an angle in the range of approximately 15 to approximately 50 degrees.

6. An instrument as defined in claim 1 wherein the heating element further comprises a material that can be bent and configured during surgery in order to reach tissue otherwise difficult to access.

7. An instrument as defined in claim 6 wherein the material has a hardness value of less than about 40 Rockwell C.

8. An instrument as defined in claim 1 wherein the working surface further comprises a coating of electrically-insulating non-stick material to reduce the accumulation of coagulum on the working surface.

9. An instrument as defined in claim 1 wherein the elongated shaft has a distal region adjacent to the distal end, the instrument further comprising a heater support member adjacent to the distal end and interposed between the working end and the electrode leads, the heater support member having a low thermal conductance so that conduction of heat from the working end to the distal region of the elongated shaft is reduced.

10. An instrument as defined in claim 1 wherein the elongated shaft further comprises a flexible portion near the distal end to permit insertion of the elongated shaft into a curved passageway.

11. A heating element for use in an endoscopic instrument comprising:

a substrate integrally formed of a heating element and having both a high-temperature working surface region for contacting tissue, and a low-temperature region for disposing the heating element adjacent a distal end of an elongated shaft, the high-temperature working surface region having a working surface and a cross-section extending perpendicularly to the working surface, the working surface maintained at an auto-regulated temperature, the substrate comprising a material having a skin depth extending throughout the cross-section of the high temperature working region responsive to the temperature of the high-temperature working surface region and that decreases as the temperature of the high-temperature working surface region falls below the auto-regulated temperature; and

an overlayer disposed on the low-temperature region of the substrate, and the overlayer having a low thermal conductance for reducing the conductance of heat from the high-temperature working surface region to the low-temperature region of the substrate.

12. A working end as defined in claim 11 wherein the overlayer further comprises a material having a low electrical resistance.

13. A working end as defined in claim 12 wherein the material of said metal substrate further comprises a material that exhibits a Curie transition in permeability.

14. A working end as defined in claim 13 wherein the material further comprises a ferromagnetic material.

15. A working end as defined in claim 14 wherein the material further comprises an alloy of iron and nickel, wherein the alloy further comprises nickel having a concentration in the range of approximately 35 percent to approximately 55 percent by weight.

16. A working end as defined in claim 11 wherein the substrate has a thickness approximately eight to ten times the skin depth of the substrate at working surface temperatures below the auto-regulation temperature.

17. A working end as defined in claim 11 wherein the working surface further comprises a tapered edge for thermally-enhanced cutting of tissue at a temperature in the range of the auto-regulated temperature, wherein the tapered edge defines an apex having an angle in the range of approximately 15 to approximately 50 degrees.

18. A working end as defined in claim 11 wherein the heating element further comprises a material that can be bent and configured during surgery in order to reach tissue otherwise difficult to access.

19. A working end defined in claim 18 wherein the material has a hardness value of less than about 40 Rockwell C.

20. A working end as defined in claim 11 wherein the working surface further comprises a coating of electrically-insulating non-stick material to reduce coagulum accumulation on the working surface.