Electrically heated surgical cutting instrument

Abstract

A surgical cutting instrument includes an electrically heated cutting edge and an automatic control system for maintaining the cutting edge at a constant high temperature for sterilizing the blade, cutting tissue, and cauterizing the incised tissue to reduce hemorrhage from the cut surfaces of the tissues (hemostasis).

I claim: 
     
       1. A surgical instrument for cutting tissue with simultaneous hemostasis, the instrument comprising: a blade .[.shaped support wafer of electrically insulating material.]. having .[.disposed thereon.]. an electrically heatable element of electrically conductive material having a resistance which varies as a function of the temperature thereof, the element including a plurality of sections which form segments or portions .[.of a.]. .Iadd.disposed in the region along the .Iaddend.tissue cutting edge of said .[.support wafer.]. .Iadd.blade,.Iaddend.each of said sections conducting electrical current .[.along said edge.]. for .[.directly.]. heating .Iadd.segments along said .Iaddend.edge; and   connection means .Iadd.for .Iaddend.providing electrical connections to each of said sections for independently supplying electrical power thereto for maintaining the resistance of each of said sections at a substantially constant selected value.   
     
     
       2. A surgical instrument as in claim 1 comprising: means for each of said sections operatively coupled thereto for sensing the electrical resistance of the corresponding section;   circuit means for each of said sections having an input for receiving electrical current from a source and being responsive to the electrical resistance of the corresponding section of said element for altering the electrical power supplied through said connection means to the corresponding section from the signal received at said input to maintain the temperature of the corresponding section substantially at a preselected value independent of the temperature of another section of said element.   
     
     
       3. A surgical instrument as in claim 2 wherein each of said circuit means comprise a plurality of circuit elements and said corresponding section connected in a bridge circuit having first and second pairs of bridge terminals, and including control means coupling said input to the first pair of bridge terminals, and bridge-balance sensing means connected to the second pair of bridge terminals and to said control means for altering the electrical power applied through the bridge circuit to said corresponding section for maintaining the resistance thereof substantially at a preselected value. .Iadd. 4. A surgical instrument for cutting tissue with simultaneous hemostasis, the instrument comprising: blade-shaped means of said instrument that has an edge which forms the tissue-cutting edge thereof; and   a plural number of heater means each disposed along the tissue-cutting edge and each capable of being heated to elevate the temperature of the blade-shaped means in said regions of the tissue-cutting edge. .Iaddend..Iadd. 5. A surgical instrument as in claim 4 wherein:   each of said heater means elevates the temperature in the corresponding region of said tissue-cutting edge to within the range between 300° C. and 1000° C. .Iaddend..Iadd. 6. A surgical instrument as in claim 4 wherein:   said blade-shaped means is formed of non-metallic material. .Iaddend..Iadd. 7. A surgical instrument as in claim 4 wherein:   said blade-shaped means includes a ceramic material. .Iaddend. .Iadd. 8. A surgical instrument as in claim 4 wherein:   said blade-shaped means includes electrically insulative material. .Iaddend..Iadd. 9. A surgical instrument as in claim 4 wherein:   each of said heater means elevates the temperature of said corresponding region in response to an electrical signal independently applied thereto. .Iaddend..Iadd. 10. A surgical instrument as in claim 4 comprising:   a circuit means connecting each of said heater means to a source of electrical power for independently controlling the flow of an electrical current through a corresponding one of said heater means to maintain the average operating temperature thereof within said range. .Iaddend. .Iadd. 11. A surgical instrument as in claim 10, said circuit means further including: resistance measuring means disposed adjacent said tissue-cutting edge for measuring the resistance of said heater means for said independently controlling of said flow of electrical current through said heater means in response thereto. .Iaddend..Iadd. 12. A surgical instrument as in claim 10, said circuit means further including: thermocouple means, disposed near said tissue-cutting edge, for measuring the temperature of said tissue-cutting edge for said independently controlling of said flow of electrical current through said heater means in response thereto. .Iaddend. .Iadd. 13. A surgical instrument for cutting tissue with simultaneous hemostasis, the instrument comprising:   blade means having a tissue-cutting edge; and   a plural number of heater means each disposed along a region of the cutting edge and each capable of being heated in the corresponding region of said edge and each having a physical parameter which varies as a function of temperature to increase power dissipation in response to selective cooling of regions along said edge upon contact with tissue being cut such that each of said corresponding regions of said tissue-cutting edge is maintained at a selected temperature range. .Iaddend..Iadd. 14. A surgical instrument as in claim 13 wherein:   each of said heater means elevates the temperature in the corresponding region of said tissue-cutting edge to within the range between 300° C. and 1000° C. .Iaddend. .Iadd. 15. A surgical instrument as in claim 13 wherein:   said blade-shaped means is formed of non-metallic material. .Iaddend..Iadd. 16. A surgical instrument as in claim 13 wherein:   said blade-shaped means includes a ceramic material. .Iaddend..Iadd. 17. A surgical instrument as in claim 13 wherein:   said blade-shaped means includes electrically insulative material. .Iaddend..Iadd. 18. A surgical instrument as in claim 13 wherein:   each of said heater means elevates the temperature of said corresponding region in response to an electrical signal independently applied thereto. .Iaddend..Iadd. 19. A surgical instrument as in claim 13 wherein:   a circuit means connecting each of said heater means to a source of electrical power for independently controlling the flow of an electrical current through a corresponding one of said heater means to maintain the average operating temperature thereof within said range. .Iaddend.