Surgical cutting instrument having electrically heated cutting edge

Abstract

A surgical cutting instrument includes an electrically heated cutting edge and a power supply 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). .Iadd.

I claim: 
     
       1. A surgical instrument for cutting tissue with simultaneous hemostasis, the instrument comprising: insulating support means having .Iadd.as a portion thereof .Iaddend.a tissue-cutting edge .[.and including thereon.]. .Iadd.region and including in physical contact with said support means .Iaddend.an electrically-heatable element of electrically-conductive material disposed on said edge region defining a cutting edge to contact tissue and to conduct electrical current along a plurality of parallel current paths for directly heating the cutting edge in response to electrical signal applied thereto; and   connection means on said instrument providing electrical connections to said element for supplying electrical signal thereto to be conducted along a plurality of parallel current paths.   
     
     
       2. A surgical instrument as in claim 1 wherein said electrically-heatable element includes a substantially continuous conductive layer disposed adjacent the cutting edge; and said connection means includes a pair of electrodes which are disposed in spaced relationship on opposite sides of said support means and which are connected to said conductive layer on opposite sides of the cutting edge for conducting current along a plurality of parallel current paths oriented substantially laterally across the cutting edge.   
     
     
       3. A surgical instrument as in claim 1 wherein: .[.said.]. electrodes are disposed on opposite sides of said support means; and   the electrically-heatable element includes a plurality of discrete electrically-heatable elements disposed to traverse the cutting edge .[.of said support means.]. and connected at the ends thereof to electrodes on opposite sides of said support means.   
     
     
       4. A surgical instrument as in claim 1 wherein: said electrically-heatable element on said support means is formed of electrically-conductive material which has positive-temperature coefficient of resistance; and   said connection means includes a source of substantially constant voltage connected to .[.said pair of.]. electrodes for maintaining the voltage across the element substantially constant as portions of said element contact tissue. .Iadd.5. A hemostatic surgical cutting blade comprising:   a cutting blade having a tissue cutting edge;   an electrically heatable element of electrically conductive material thermally connected to and at least extending along the area of the cutting edge such that said edge may be maintained within a predetermined temperature range; and   two or more electrodes disposed in spaced relationship on the cutting blade and connected to said electrically conductive material for conducting current along a plurality of parallel current paths. .Iaddend..Iadd. 6. The hemostatic surgical cutting blade claimed in claim 5 wherein said electrodes are disposd in lateral spacial relationship on opposite sides of said cutting edge for conducting current along a plurality of parallel current paths oriented substantially laterally across the cutting edge. .Iaddend..Iadd. 7. The hemostatic surgical cutting blade claimed in claim 5 wherein said electrically heatable element is further defined as comprising a plurality of discrete electrically heatable elements. .Iaddend..Iadd. 8. The hemostatic surgical cutting blade claimed in claim 5 wherein said electrically heatable element is formed from a material having a positive-temperature coefficient. .Iaddend. .Iadd. 9. The method of cutting tissue with simultaneous hemostasis comprising the steps of:   contacting the tissue to be cut with a tissue cutting edge at an elevated temperature;   establishing the elevated temperature by conducting current along a plurality of substantially parallel current paths located along said tissue cutting edge; and   increasing power dissipation in regions of the edge which are selectively cooled upon contact with tissue for maintaining the temperature of the edge within a selected range. .Iaddend..Iadd. 10. A method of cutting tissue with simultaneous hemostasis comprising:   conducting current along a plurality of substantially parallel current paths oriented laterally across a supported tissue cutting edge;   dissipating power in regions of said tissue cutting edge responsive to selective cooling of said regions by reason of contact with tissue; thereby maintaining said tissue cutting edge at a selected temperature range. .Iaddend..Iadd. 11. A method of hemostatic surgery as in claim 9 wherein:   current is conducted along a plurality of substantially parallel current paths which are discrete. .Iaddend..Iadd. 12. A method of hemostatic surgery according to claim 9 wherein:   the resistance of the parallel current paths increases with increasing temperature thereof. .Iaddend..Iadd. 13. A method of hemostatic surgery according to claim 12 wherein:   a constant voltage is impressed upon the current paths. .Iaddend.