U.S. patent number RE29,088 [Application Number 05/625,845] was granted by the patent office on 1976-12-28 for surgical cutting instrument having electrically heated cutting edge.
Invention is credited to Robert F. Shaw.
United States Patent |
RE29,088 |
Shaw |
December 28, 1976 |
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.
Inventors: |
Shaw; Robert F. (Portola
Valley, CA) |
Family
ID: |
26969386 |
Appl.
No.: |
05/625,845 |
Filed: |
October 28, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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63645 |
Aug 13, 1970 |
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681737 |
Nov 9, 1967 |
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Reissue of: |
295879 |
Oct 10, 1972 |
03768482 |
Oct 30, 1973 |
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Current U.S.
Class: |
606/29;
30/140 |
Current CPC
Class: |
A61B
18/082 (20130101); A61B 18/1402 (20130101); A61B
2018/00119 (20130101) |
Current International
Class: |
A61B
18/08 (20060101); A61B 18/04 (20060101); A61B
18/14 (20060101); A61B 017/32 (); A61N
003/00 () |
Field of
Search: |
;128/303.1,303.14,303.17
;30/140 ;219/233,242 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Lyon & Lyon
Parent Case Text
RELATED APPLICATION
This application is a reissue of Pat. 3,768,482 which matured from
application 295,879 filed October 10, 1972 and which is a
continuation of continuation-in-part of U.S. Pat. Application Ser.
No. 63,645 filed August 13, 1970, now abandoned, which is a
continuation of U.S. Pat. Application Ser. No. 681,737 filed Nov.
9, 1967, now abandoned. .Iaddend.
Claims
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.
Description
The control of bleeding during surgery accounts for a major portion
of the total time involved in an operation. The bleeding that
occurs when tissue is incised obscures the surgeon's vision,
reduces his precision and often dictates slow and elaborate
procedures in surgical operations. Each bleeding vessel must be
grasped in pincer-like clamps to stop the flow of blood and the
tissue and vessel within each clamp must then be tied with pieces
of fine thread. These ligated masses of tissue die and decompose
and thus tend to retard healing and promote infection.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a surgical cutting
instrument having a cutting edge which is electrically heated to a
constant high temperature for sterilizing the blade, cutting the
tissue and cauterizing the surfaces of the incision, thereby
allowing surgery to be more rapidly performed. This is accomplished
in accordance with the illustrated embodiment of this invention by
providing electrically heated elements disposed to form the cutting
edge of the blade and by providing a common constant voltage source
which operates to maintain the cutting edge at a high substantially
constant temperature during its use. The hot cutting edge according
to the present invention decreases the amount of tissue that is
damaged and reduces the tendency of the instrument to stick to the
heated tissue in the incision. In one embodiment, the material used
in the electrically heated cutting edge has a positive temperature
coefficient of resistance. The temperature at which the cutting
edge of the blade is maintained depends upon such factors as the
nature of the tissue to be cut, the speed of cutting desired, the
degree of tissue coagulation desired, and the non-adherence of the
blade to the incised tissue and generally is maintained between
300.degree.-1,000.degree. Centigrade for typical incisions in
typical human tissue. The cutting edge includes many parallel
current paths in a conductive material connected between the
terminals of a constant-voltage power source. The operating
temperature of the cutting edge is controlled by altering the
voltage between the terminals.
The handle of the cutting instrument is thermally insulated from
the blade to permit comfortable use of the instrument and the
handle and blade with its electrically-heated cutting edge are
detachable for easy replacement and interchangeability with blades
having cutting edges of various shapes and sizes determined by the
nature of the incision to be made and the tissue to be cut.
DESCRIPTiON OF THE DRAWINGS
FIGS. 1 and 2 are pictorial views of embodiments of cutting
instruments according to the present invention; and
FIG. 3 is an end sectional view of the embodiment of FIG. 1 showing
the heater element disposed as the cutting edge of the blade
between electrodes on opposite sides thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGS. 1 and 3 of the drawing, there is shown the
surgical cutting instrument 9 including a thin ceramic card 63 in
the desired shape of a surgical cutting blade which is detachable
from the handle or holder 10. An electrical heating element 61 is
disposed in the region of, i.e. on or about, the cutting edge 62 of
ceramic card 63 between electrodes 65 and 67 which are electrically
connected to a constant voltage source through the cable 14 and the
connectors 71 and 73. The element 61 may be a continuous conductive
film attached to the card 63, for example, using conventional
vapor-deposition processes. The material used for the element 61
may be tantalum nitride or other similar material having a positive
temperature coefficient of resistance. Thus, as a portion of the
element cools when in contact with tissue, the resistance of such
portion of the element decreases and draws increased current from
the constant voltage source 75. This localizes the portion of the
element 61 in which additional power is dissipated to the portion
cooled on contact with tissue. The temperature of such portions of
the element may thus be maintained substantially constant as the
cutting edge comes in contact with tissue being cut. Other suitable
materials having positive temperature coefficients of resistance
for use as the element 61 include tungsten, nickel, platinum,
chromium, alloys of such metals, and the like.
In the embodiment of the present invention illustrated in FIGS. 1
and 3, the heating element 61 is laterally disposed across the
cutting edge 62 of the blade-like support card 63 to form a
continuum of current-conducting paths along the length of the
cutting edge. These current-conducting paths of heating element 61
are all parallel-connected between the contact electrodes 65 and 67
and which are disposed on opposite sides of the support card 63.
These contact electrodes may be formed of a material such as
platinum or tungsten, or the like, which makes good contact with
the heating element material and which does not readily oxidize at
elevated operating temperatures. Alternatively, the heating element
61 may also be arranged to traverse the cutting edge 62 as
discrete, closely-spaced elements 69 that are all
parallel-connected between opposite-side electrodes 65 and 67 on
the card 63, as shown in FIG. 2. Such discrete elements are
connected on one side of the card 63 to the electrode 67 and on the
other side of the card to electrode 65. In the limit, the heating
elements 69, as shown in FIG. 2, may be sufficiently closely
located along the cutting edge 62 in parallel connection between
the opposite-side electrodes 65 and 67, as to perform substantially
as a continuous conductive film, as shown in FIG. 1.
In each of the illustrated embodiments, the electrodes 65 and 67
and heating elements 61 or 69 may be conductive material which is
vapor-deposited in the desired interconnected patterns on a
suitable electrically-insulating ceramic card 63. Alternatively,
the electrodes and heater elements may be etched to shape on a card
63 whose side surfaces and edges are coated with the selected
conductive materials.
In each of these embodiments, the electrodes 65, 67 are connected
through conductors 14 and suitable electrical connectors 71, 73
mounted in the handle 10 to a source 75 of substantially constant
voltage. This source 75 may be a conventional, well-regulated power
supply or other low-output impedance supply which is capable of
delivering the total current required by all portions of heating
element 61 (or by all discrete elements 69) while maintaining the
voltage between electrodes 65 and 67 substantially constant. In
this way, each portion of heating element 61 (or discrete element
69) which cools down when placed in contact with tissue during
surgical use decreases in resistance between electrodes (for
positive temperature coefficient of resistance). With constant
voltage applied to the electrodes, the cooled regions draw
correspondingly more current and dissipate more power in the cooled
region, thereby tending to maintain the heating element all along
the cutting edge at the preselected operating temperature. The
operating temperature of the cutting edge is thus selected by
altering the value of the constant voltage supplied by source 75.
To assure substantially uniform operating temperature over the
length of the cutting edge 62, the heating element 61 (or the
discrete elements 69 closely spaced about the edge) may have
substantially uniform resistance per unit area. The ceramic card 63
may be formed of high thermal conductivity material such as
aluminum oxide, or the like, to assure more uniform operating
temperature along the length of the cutting edge.
* * * * *