U.S. patent application number 11/706121 was filed with the patent office on 2007-12-27 for bipolar cutting and coagulating forceps.
This patent application is currently assigned to Gyrus Medical, Inc.. Invention is credited to Nigel Mark Goble, Scott T. Latterell, Colin Charles Owen, Scott R. Sanders, Douglas S. Wahnschaffe.
Application Number | 20070299439 11/706121 |
Document ID | / |
Family ID | 34808254 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070299439 |
Kind Code |
A1 |
Latterell; Scott T. ; et
al. |
December 27, 2007 |
Bipolar cutting and coagulating forceps
Abstract
A bipolar electrosurgical instrument comprises a handle (5), a
body (1) joined to the handle, and a jaw assembly (12) joined to
the body and arranged such that manipulation of the handle allows
the opposed jaws of the jaw assembly to be opened and closed with
respect to one another. A first of said opposed jaws (14) has at
least a first coagulating electrode, and the other of said opposed
jaws (13) has at least a second coagulating electrode and a cutting
electrode (16) separated from the second coagulating electrode by
an insulating member (17). The instrument is manipulated at the
surgical site such that the jaws of the jaw assembly (12) are open
with respect to one another, with the cutting electrode (16) and at
least one of the first and second coagulating electrodes contacting
tissue at the surgical site. A radio frequency electrosurgical
signal is supplied between the cutting electrode and the at least
one coagulating electrode, and the electrosurgical instrument is
moved while maintaining the jaws (13, 14) in their open position so
as to cut tissue at the surgical site.
Inventors: |
Latterell; Scott T.;
(Minneapolis, MN) ; Wahnschaffe; Douglas S.;
(Otsego, MN) ; Sanders; Scott R.; (Longmont,
CO) ; Goble; Nigel Mark; (Berkshire, GB) ;
Owen; Colin Charles; (Surrey, GB) |
Correspondence
Address: |
NIKOLAI & MERSEREAU, P.A.
900 SECOND AVENUE SOUTH
SUITE 820
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Gyrus Medical, Inc.
Maple Grove
MN
|
Family ID: |
34808254 |
Appl. No.: |
11/706121 |
Filed: |
March 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10770133 |
Feb 2, 2004 |
7204835 |
|
|
11706121 |
Mar 26, 2007 |
|
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|
Current U.S.
Class: |
606/48 ; 606/45;
606/50; 606/51; 606/52 |
Current CPC
Class: |
A61B 18/1442 20130101;
A61B 18/1206 20130101; A61B 2018/00607 20130101; A61B 2018/0063
20130101; A61B 2018/124 20130101; A61B 18/1445 20130101 |
Class at
Publication: |
606/048 ;
606/045; 606/050; 606/051; 606/052 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1-14. (canceled)
15. A bipolar electrosurgical instrument according to claim 14
wherein the rail protrudes from the insulating member by a distance
of between 25 and 75 microns.
16. A bipolar electrosurgical instrument according to claim 15
wherein the rail protrudes from the insulating member by a distance
of between 40 and 60 microns.
17. A bipolar electrosurgical instrument according to claim 16
wherein the rail protrudes from the insulating member by a distance
of approximately 50 microns.
18. A bipolar electrosurgical instrument according to any of claims
14 to 17 wherein the width of the rail is between 25 and 75
microns.
19. A bipolar electrosurgical instrument according to claim 18
wherein the width of the rail is between 40 and 60 microns.
20. A bipolar electrosurgical instrument according to claim 19
wherein the width of the rail is approximately 50 microns.
21. A method of electrosurgically cutting tissue at a surgical site
comprising the steps of (i) providing a bipolar electrosurgical
instrument including a handle, a jaw assembly arranged such that
manipulation of the handle allows the opposed jaws of the jaw
assembly to be opened and closed with respect to one another; a
first of said opposed jaws having at least a first coagulating
electrode; the other of said opposed jaws having at least a second
coagulating electrode and a cutting electrode separated from the
second coagulating electrode by an insulating member, (ii)
providing an electrosurgical generator comprising one or more
sources of RF output power, a controller operable to control the
generator such that it is capable of providing a first cutting RF
signal to the electrosurgical instrument or a second coagulating RF
signal to the electrosurgical instrument, and, in a combined mode,
to deliver both first and second RF signals, the signals being fed
to the electrosurgical instrument such that, in the combined mode,
the cutting signal is delivered between the cutting electrode and
at least one of the first and second coagulating electrodes, and
the coagulating RF signal is delivered between the first and second
coagulating electrodes, (iii) manipulating the electrosurgical
instrument at the surgical site such that the jaws of the jaw
assembly are open with respect to one another, (iv) closing the
jaws of the jaw assembly such that tissue at the target site is
contained therebetween, (v) supplying the combined radio frequency
electrosurgical signal to the electrosurgical instrument from the
electrosurgical generator, (vi) applying a first, relatively low,
pressure to the tissue by the jaw assembly in order to cause the
coagulation of the tissue held therebetween, and (vii) applying a
second, relatively higher, pressure to the tissue by the jaw
assembly in order to cause the cutting of the tissue.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a method of electrosurgically
cutting tissue, and to an electrosurgical system for cutting
tissue.
[0003] 2. Discussion of the Prior Art
[0004] Electrosurgical cutting forceps are a commonly used tool in
electrosurgery. U.S. Pat. No. 5,445,638 is a typical example, in
which a pair of jaws are used to grip and coagulate tissue, and
then a mechanical cutting blade moves between the jaws in order to
cut the tissue. U.S. Pat. No. 6,554,829 is a more recent version of
this type of instrument, still employing a pair of jaws and a
mechanical cutting blade.
[0005] An alternative form of cutting forceps uses an
electrosurgical cutting member as opposed to a mechanical cutting
member. U.S. Pat. No. 6,174,309 is one such example, in which
tissue is grasped between jaws, and then an electrosurgical cutting
voltage is supplied to a cutting member located on one of the jaws.
In all of these devices, the amount of tissue able to be cut is
limited by the size of the jaws used to grasp the tissue while it
is being cut.
[0006] The present invention attempts to provide an improvement
over these prior art cutting devices, especially in that the
cutting of relatively larger amounts of tissue is facilitated.
SUMMARY OF THE INVENTION
[0007] Accordingly, the invention provides a method of
electrosurgically cutting tissue at a surgical site comprising the
steps of
[0008] (i) providing a bipolar electrosurgical instrument including
a handle, a jaw assembly arranged such that manipulation of the
handle allows the opposed jaws of the jaw assembly to be opened and
closed with respect to one another; a first of said opposed jaws
having at least a first coagulating electrode; the other of said
opposed jaws having at least a second coagulating electrode; and a
cutting electrode separated from the second coagulating electrode
by an insulating member,
[0009] (ii) manipulating the electrosurgical instrument at the
surgical site such that the jaws of the jaw assembly are open with
respect to one another, with the cutting electrode and at least one
of the first and second coagulating electrodes contacting tissue at
the surgical site,
[0010] (iii) supplying a radio frequency electrosurgical signal
between the cutting electrode and the at least one coagulating
electrode, and
[0011] (iv) moving the electrosurgical instrument while maintaining
the jaws in their open position so as to cut tissue at the surgical
site.
[0012] Unlike the prior art devices, in which only tissue grasped
between the jaws is cut, the present method moves the instrument
with its jaws in the "open" position in order to cause tissue
cutting. Preferably the electrosurgical instrument has a
longitudinal axis and the instrument is moved longitudinally along
said axis in order to cut tissue at the surgical site. Conveniently
the first jaw has an inner face opposite the second jaw, and the
cutting electrode is positioned on the inner face of the first jaw.
In one convenient arrangement, the cutting electrode comprises a
longitudinally extending rail.
[0013] The method of the present invention also allows the
electrosurgical instrument to be used to coagulate as well as cut
tissue. Accordingly, the method includes the additional steps of
manipulating the handle in order to close the jaw assembly such
that tissue at the surgical site is grasped therebetween, and
supplying a radio frequency electrosurgical signal between the
first and second coagulating electrodes so as to cause the
coagulation of the tissue grasped between the jaws. In one
arrangement the coagulation step is carried out following the
movement of the instrument in order to cut tissue at the surgical
site. In this way, the instrument can be used in order to control
any bleeding caused by the cutting of the tissue.
[0014] Alternatively, the method includes the step of supplying a
combined radio frequency signal consisting of a first cutting RF
signal and a second coagulating RF signal, the first RF cutting
signal being delivered between the cutting electrode and the at
least one coagulating electrode, and the second coagulating RF
signal being delivered between the first and second coagulating
electrodes. In this way, the instrument is capable of
simultaneously delivering a coagulating signal to the tissue as the
tissue is being cut by the movement of the instrument. In a
preferred arrangement, the combined radio frequency signal
comprises a signal alternating constantly between the first cutting
RF signal and the second coagulating RF signal so that the two are
interleaved. There may also conveniently be provided adjustment
means for varying the ratio of the blend mode so as to vary that
part of the blend signal that is the first RF cutting signal as
compared with the part of the blend signal that is the second RF
coagulating signal. The adjustment means is conveniently operable
by the user of the electrosurgical instrument, but can
alternatively be automatically adjusted in response to feedback
from one or more sensors detecting a parameter of the tissue, such
as electrical impedance.
[0015] By the terms "RF cutting signal" and "RF coagulating signal"
there is hereby meant any RF signal capable of cutting or
coagulating tissue respectively. For example the signals may differ
with respect to their voltage, the RF cutting signal having a
higher voltage such that it is capable of cutting tissue, whereas
the RF coagulating signal having a relatively lower voltage such
that it is capable of coagulating but not cutting tissue.
Additionally or alternatively, the RF cutting signal may differ
from the RF coagulating signal in terms of its waveform rather than
voltage. For example the RF coagulating signal may comprise shorter
bursts of the same signal used for the cutting of tissue.
[0016] Where the terms "coagulate" or coagulating" are used, there
is hereby meant the prevention of bleeding following a
tissue-cutting operation, as well as a process in which the
collagen within tissue is made viscous so as to prevent blood flow
through a blood vessel, for example prior to cutting. The terms are
also herein meant to include vessel sealing, in which the walls of
the vessel are fused together in order to seal the vessel.
[0017] The invention further resides in an electrosurgical system
comprising
[0018] (i) a bipolar electrosurgical instrument including a handle,
a jaw assembly arranged such that manipulation of the handle allows
the opposed jaws of the jaw assembly to be opened and closed with
respect to one another; a first of said opposed jaws having at
least a first coagulating electrode; the other of said opposed jaws
having at least a second coagulating electrode; and a cutting
electrode separated from the second coagulating electrode by an
insulating member, and
[0019] (ii) an electrosurgical generator comprising one or more
sources of RF output power, a controller operable to control the
generator such that it is capable of providing a first cutting RF
signal to the electrosurgical instrument or a second coagulating RF
signal to the electrosurgical instrument, and, in a combined mode,
to deliver both first and second RF signals, the signals being fed
to the electrosurgical instrument such that, in the combined mode,
the cutting signal is delivered between the cutting electrode and
at least one of the first and second coagulating electrodes, and
the coagulating RF signal is delivered between the first and second
coagulating electrodes.
[0020] As described in our co-pending UK patent application
0305018.4, the generator may comprise a single RF source so that in
the combined mode the generator system alternates constantly
between delivering the cutting and coagulating signals.
Alternatively, the generator comprises first and second RF sources
operating at different frequencies, so as to deliver the cutting
and coagulating signals simultaneously. As described in the patent
application mentioned above, there is conceivably provided
adjustment means for varying the ratio of the combined mode so as
to vary that part of the combined signal that is the first RF
cutting signal as compared with the part of the combined signal
that is the second RF coagulating signal. Conveniently, the
adjustment means is operable by the user of the electrosurgical
instrument, but it may conceivably also be automatically adjusted
in response to feedback from one or more sensors detecting a
parameter of the tissue, such as the tissue impedance.
[0021] The invention also resides in a bipolar electrosurgical
instrument including a handle, a jaw assembly arranged such that
manipulation of the handle allows the opposed jaws of the jaw
assembly to be opened and closed with respect to one another; a
first of said opposed jaws having at least a first coagulating
electrode; the other of said opposed jaws having at least a second
coagulating electrode; and a cutting electrode and separated from
the second coagulating electrode by an insulating member, wherein
the cutting electrode is in the form of a longitudinal rail mounted
on the insulating member, the rail protruding from the insulating
member by a distance of less than 100 microns. The dimensions of
the rail have been found to be very important for ensuring that an
effective electrosurgical cut occurs. Preferably the rail protrudes
from the insulating member by a distance of between 25 and 75
microns, more preferably between 40 and 60 microns, and most
preferably approximately 50 microns. Preferably, the width of the
rail is between 25 and 75 microns, more preferably between 40 and
60 microns, and most preferably approximately 50 microns.
[0022] According to a further aspect of the invention, a method of
electrosurgically cutting tissue at a surgical site comprises the
steps of
[0023] (i) providing a bipolar electrosurgical instrument including
a handle, a jaw assembly arranged such that manipulation of the
handle allows the opposed jaws of the jaw assembly to be opened and
closed with respect to one another; a first of said opposed jaws
having at least a first coagulating electrode; the other of said
opposed jaws having at least a second coagulating electrode; and a
cutting electrode separated from the second coagulating electrode
by an insulating member,
[0024] (ii) providing an electrosurgical generator comprising one
or more sources of RF output power, a controller operable to
control the generator such that it is capable of providing a first
cutting RF signal to the electrosurgical instrument or a second
coagulating RF signal to the electrosurgical instrument, and, in a
combined mode, to deliver both first and second RF signals, the
signals being fed to the electrosurgical instrument such that, in
the combined mode, the cutting signal is delivered between the
cutting electrode and at least one of the first and second
coagulating electrodes, and the coagulating RF signal is delivered
between the first and second coagulating electrodes,
[0025] (iii) manipulating the electrosurgical instrument at the
surgical site such that the jaws of the jaw assembly are open with
respect to one another,
[0026] (iv) closing the jaws of the jaw assembly such that tissue
at the target site is contained therebetween,
[0027] (v) supplying the combined radio frequency electrosurgical
signal to the electrosurgical instrument from the electrosurgical
generator,
[0028] (vi) applying a first, relatively low, pressure to the
tissue by the jaw assembly in order to cause the coagulation of the
tissue held therebetween, and
[0029] (vii) applying a second, relatively higher, pressure to the
tissue by the jaw assembly in order to cause the cutting of the
tissue.
DESCRIPTION OF THE DRAWINGS
[0030] The invention will now be further described, by way of
example only, with reference to the accompanying drawings, in
which;
[0031] FIG. 1 is a schematic sectional view of an endoscopic
electrosurgical instrument in accordance with the invention,
[0032] FIG. 2 is a perspective view of the jaw assembly of the
instrument of FIG. 1,
[0033] FIG. 3 is a cross-sectional view of the body of the
instrument of FIG. 1,
[0034] FIG. 4 is an end view of the jaw assembly of FIG. 2,
[0035] FIG. 5 is a side view of the jaw assembly of FIG. 2,
[0036] FIG. 6 is a circuit diagram of a switching circuit used in
conjunction with the electrosurgical instrument of FIG. 1,
[0037] FIG. 7 is a schematic side view of an alternative embodiment
of electrosurgical instrument for use in open procedures and
constructed in accordance with the invention,
[0038] FIG. 8 is an enlarged view of a portion of one of the jaws
of the instrument of FIG. 7,
[0039] FIG. 9 is a sectional end view of one of the jaws of the
instrument of FIG. 7, and
[0040] FIG. 10 is a sectional end view of the other jaw of the
instrument of FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] Referring to FIG. 1, a bipolar forceps device includes an
elongated tubular shaft 1 with a proximal end 2, distal end 3, and
a lumen 4 which extends for the entire length of the tubular
member. At the proximal end 2 of the tubular member 1 is a
scissors-type handle assembly 5 with a first handle 6 and a second
handle 7. The second handle 7 is pivotable with respect to the
first, about pivot pin 8. In a known design of actuation mechanism,
the second handle 7 has a pin 9 affixed to the top thereof, such
that movement of the handle causes a corresponding movement to a
sphere 10 supported in a U-shaped cradle 11.
[0042] Fitted into the distal end 3 of the tubular member 1 is a
forceps jaw assembly 12, more particularly shown in FIG. 2. The jaw
assembly 12 comprises a first jaw member 13 and a second jaw member
14, pivotally joined to each other by an insulated rivet 15. Jaw
member 13 is provided with a relatively long, but narrow cutting
electrode 16 that is isolated from jaw member 13 by a ceramic
insulator strip 17 that supports the cutting electrode. As shown in
FIG. 3, three generally rigid electrically conductive rods 18, 19
and 20, each covered with a layer of electrical insulation, extend
through the lumen 4 of the tubular member 1. The rods 18, 19 are
pivotally connected to the respective jaw members 13, 14 by rigid
links 21, whilst rod 20 is connected by means of a wire 24 (as best
shown in FIG. 5) to the cutting electrode 16. The proximal ends of
the rods 18, 19 and 20 extend from the tubular member through the
sphere 10 and terminate in a connector 22, by which means the
device can be attached to an electrosurgical generator 26.
[0043] As shown in FIG. 2, the cutting electrode 16 is in the form
of an elongate metal rail, extending along the length of the jaw
member 13. The rail 16 is mounted atop the ceramic insulator 17
such that it is insulated from the conductive jaw member 13. The
rail 16 is typically 50 to 100 microns in width, and protrudes from
the ceramic insulator 17 by a distance of approximately 50 microns.
When the jaw assembly 12 is in its closed position, the rail 16 is
received in a corresponding longitudinal recess 23 in the jaw
member 14, best shown in FIG. 4. A compressible strip 27 of
insulting material is provided in the recess 23.
[0044] The operation of the device will now be further described.
When tissue is to be cut, the jaw assembly 12 is brought adjacent
the tissue to be cut, with the jaw assembly in its open position
and the tissue positioned in the nip 25 of the jaw assembly. A
cutting signal from the electrosurgical generator 26 is supplied,
via the rod 20, to the cutting electrode 16, and the forceps device
is moved longitudinally in the direction of the arrow shown in FIG.
5. Tissue bridging the cutting electrode 16 and one or both of the
jaw members 13 and 14 is severed by the electrosurgical signal as
the device is translated longitudinally, thereby forming a
continuously progressing longitudinal cut line in the tissue. The
jaw assembly is maintained in its open position throughout this
process, defining the nip 25 in which the tissue is
constrained.
[0045] The device can also be used to coagulate tissue, in a more
conventional manner, using the jaw assembly in its closed position.
The jaw assembly is closed, capturing tissue between the jaw member
13 and the jaw member 14. The cutting rail 16 is received in the
recess 23 and, without the electrosurgical cutting signal
previously described, does not have a cutting effect on the tissue
therebetween. A coagulating signal from the electrosurgical
generator 26 is supplied between the jaw members 13 and 14, via
rods 18 and 19. This causes the coagulation of the tissue held
between the jaws.
[0046] The device can also be used in a blended cutting and
coagulation mode, as described in co-pending UK patent application
0305018.4. An example of an electrical circuit to provide such an
arrangement is shown in FIG. 6. The circuit is shown generally at
30 and may be provided as a part of the output stage of the
generator 26, as a part of the forceps instrument, or as a separate
unit located between the generator and the instrument. Whichever
arrangement is employed, input connections 31 and 32 are connected
to the output of the generator 26, and output connections 33 and 34
to the rods 18 and 19, and, hence, to jaw members 13 and 14. Output
connection 35 is connected to rod 20 and, hence, to the cutting
electrode 16.
[0047] Between the input connections 31 and 32 there is a bridge
circuit comprising a first transformer 36 and a second transformer
37. First transformer 36 comprises primary winding 38 and secondary
winding 39. A switch element 40 is provided in parallel with
primary winding 38. Second transformer 37 comprises primary winding
41 and secondary winding 42. A switch element 43 is provided in
parallel with primary winding 41. Switch elements 40 and 43 are
operated by control unit 44.
[0048] The second transformer 37 is a step-down transformer in
which the secondary winding 42 is itself the primary to a further
center-tapped secondary winding 45 connected across the output
connections 33 and 34. Isolation capacitor 46 is provided between
the bridge circuit and output connection 35, and isolation
capacitors 47 and 48 between the bridge circuit and output
connections 33 and 34.
[0049] The operation of the circuit is as follows. For a
predetermined period, control unit 44 operates switch 43 to close
and provide a short circuit across the primary winding 41 of the
second transformer 37. In this arrangement, with the secondary
transformer effectively short-circuited, the output of the
generator is directed between the output connection 35 and both of
the output connections 33 and 34. This has the effect of energizing
the cutting rail 16 with a cutting voltage, as compared to the jaw
members 13 and 14, which effectively act as return electrodes for
the electrosurgical cutting operation.
[0050] After a predetermined period, the control unit 44 operates
to open switch 43 and then close switch 40 to provide a short
circuit across the primary winding 38 of the first transformer 36.
There is a short predetermined delay between the opening of switch
43 and the closing of switch 40 to ensure that both switches are
never closed at the same time (as this would provide a short
circuit across the output connections of the generator 26). With
switch 40 closed, the first transformer is effectively
short-circuited, and the output of the generator is directed
entirely to the second transformer 37. The second transformer is a
step-down transformer, and provides a lower voltage signal between
the output connections 33 and 34. This has the effect of energizing
the first and second jaw members 13 and 14 with a coagulating
voltage.
[0051] After a predetermined time, the control unit 44 opens switch
40 and then closes switch 43, reverting to the arrangement
initially described in which a cutting voltage is delivered to the
cutting rail 16. By constantly alternating between the two
conditions herein described, the circuit provides a rapidly
alternating cut and coagulation signal to a forceps device
connected thereto. In this way, the forceps device is able to cut
tissue as previously described, while simultaneously coagulating
the tissue in order to curtail bleeding.
[0052] Although the forceps device of FIGS. 1 to 5 is shown as an
endoscopic instrument, the invention can also be employed in
connection with open instruments, as will be described with
reference to FIGS. 7 to 10. The instrument shown generally at 50,
comprises two longitudinal members 51 and 52, mounted for pivotal
movement by means of pivot pin 53. The proximal end of member 51 is
in the form of handle portion 54, and the proximal end of member 52
is in the form of handle portion 55. A ratchet mechanism 56 is
provided on each handle portion for locking the handle portions
when they are moved together into their closed position.
[0053] Distal of the pivot pin 53, the longitudinal member 51 forms
a jaw member 57, while the longitudinal member 52 forms a jaw
member 58. Movement of the handle portions 54 and 55 causes the jaw
members 57 and 58 to open and close.
[0054] With reference to FIGS. 8 and 9, the jaw member 57 comprises
an integral base portion 59 on which is mounted a shim member 60,
secured by means of clips 74. The shim member comprises an
insulating strip 61, covered by a metallic surface electrode 62. A
cutting electrode assembly 63 is mounted in a recess 64 running
longitudinally along the jaw member 57. The cutting electrode
assembly 63 comprises a raised insulator block 65, typically of a
ceramic material, and a cutting electrode 66 mounted in a further
longitudinal recess in the insulator block 65. The cutting
electrode 66 is typically 100 microns in width, and protrudes from
the insulator block 65 by a distance of approx 425 microns.
[0055] The opposite jaw member 58 shown in FIG. 10 also comprises a
base portion 67 and a shim member 68. The shim member 68 also
comprises an insulting strip 69, covered by a metallic surface
electrode 70. The shim member 68 includes a central recess 71 in
which the cutting electrode assembly 63 of the jaw member 57 can be
received when the jaw members are in their closed position. At the
base of the recess 71 is a strip 72 of resilient material such as
an elastomer, such that the cutting electrode 66 bears against the
strip 72 when the jaw members are closed one against the other. A
stop member 73 (FIG. 7), mounted on one of the jaws, regulates the
separation of the jaws when they are in their closed position.
[0056] The operation of the instrument 50 will now be described.
Firstly, the instrument can be used to cut tissue, as previously
described. The jaw members 57 and 58 are held in their open
position, and tissue is manoeuvred between the jaw members. An
electrosurgical cutting signal is supplied to the cutting electrode
66, and the instrument 50 is moved longitudinally, thereby
continuously severing tissue in a longitudinal cut line as the
instrument is advanced. The surface electrodes 62 and 70 act as
return electrodes for the electrosurgical cutting signal.
[0057] In a second technique, tissue can be cut using a 2-step
process. The jaw members 57 and 58 are moved to their closed
position, gripping tissue to be cut therebetween. Then a first
coagulating RF signal is supplied between the surface electrodes 62
and 70, causing the coagulation of the tissue held between the jaw
members. Without releasing the tissue, a second cutting RF signal
is then supplied to the cutting electrode 66, causing the cutting
of the tissue held by the jaw members.
[0058] Finally in a further technique, tissue can be coagulated and
or cut using a process employing a blended signal as described with
reference to FIG. 6. In this arrangement, a signal constantly
alternating between the RF coagulating signal and the RF cutting
signal is supplied to the jaw members, the RF coagulating signal
being supplied between the surface electrodes 62 and 70, and the RF
cutting signal being supplied to the cutting electrode 66 and with
electrodes 62 and 70 acting as the return. The effect of the
alternating RF signal upon the tissue is determined by the pressure
applied to the tissue by the jaw members 57 and 58. The user of the
instrument 50 closes the jaw members 57 and 58 to grip tissue
therebetween. When the pressure applied by the jaws is at a first
relatively low level, the predominant effect of the alternating RF
signal is to cause the coagulation of the tissue held between the
jaw members. When the user of the instrument wishes to sever the
tissue held between the jaws, the user increases the pressure
applied by the jaws to a second relatively higher level. At this
relatively higher level of pressure, the predominant effect of the
alternating RF signal is to cause the cutting of the tissue held
between the jaw members 57 and 58. In this way, the user of the
instrument 50 is able to switch between the coagulation and cutting
of tissue merely by altering the pressure applied to the tissue by
the jaw members.
[0059] The devices described herein can be used in a cutting
technique in which tissue is cut, either with or without
simultaneous coagulation, in which a forceps device is moved with
its jaws held in an open condition, and in which a cutting rail
acts to cut tissue as the device is moved in a longitudinal
direction. Although suitable for both open and laparoscopic
surgery, this technique is particularly advantageous in
laparoscopic surgery, in which the excessive opening and closing of
the jaws is to be avoided or is difficult to achieve. Also
described are techniques for coagulating and cutting tissue in a
2-step process, in which the tissue is first coagulated and then
severed with the jaws maintained in a closed position. One
technique employs the pressure exerted by the jaws to regulate
whether the effect of the instrument is primarily that of tissue
coagulation or cutting.
[0060] This invention has been described herein in considerable
detail in order to comply with the patent statutes and to provide
those skilled in the art with the information needed to apply the
novel principles and to construct and use such specialized
components as are required. However, it is to be understood that
the invention can be carried out by specifically different
equipment and devices, and that various modifications, both as to
the equipment and operating procedures, can be accomplished without
departing from the scope of the invention itself.
* * * * *