Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ELECTRICAL SURGICAL INSTRUMENT
Related Application
This application is a divisional application of application serial number
2,629,276
which corresponds to International Application WO 2007/137304 filed on May 31,
2007.
Technical Field
The present invention lies in the field of surgical instruments, in particular
but not
necessarily, stapling devices. The stapling device described in the present
application is a hand-
held, fully electrically powered and controlled surgical stapler.
Medical stapling devices exist in the art. Ethicon Endo-Surgery, Inc. (a
Johnson &
Johnson company; hereinafter "Ethicon") manufactures and sells such stapling
devices. Circular
stapling devices manufactured by Ethicon are referred to under the trade names
PROXIMATE 0
PPH, CDH, and ILS and linear staplers are manufactured by Ethicon under the
*trade names
CONTOUR and PROXIMATE. In each of these exemplary surgical staplers, tissue is
compressed
between a staple cartridge and an anvil and, when the staples are ejected, the
compressed tissue is
also cut. Depending upon the particular tissue engaged by the physician, the
tissue can be
compressed too little (where blood color is still visibly present in the
tissue),.too much (where
tissue is crushed), or correctly (where the liquid is removed from the tissue,
referred to as
dessicating or blanching).
Staples to be delivered have a given length and the cartridge and anvil need
to be within an
acceptable staple firing distance so that the staples close properly upon
firing. Therefore, these
staplers have devices indicating the relative distance between the two planes
and whether or not
this distance is within the staple length firing range. Such an indicator is
mechanical and takes the
form of a sliding bar behind a window having indicated thereon a safe staple-
firing range. These
staplers are all hand-powered, in other words, they require physical
actuations by the
user/physician to position the anvil and stapler cartridge about the tissue to
be stapled and/or cut,
to close the anvil and stapler cartridge with respect to one another, and to
fire and secure the
staples at the tissue (and/or cut the tissue). No prior art staplers are
electrically powered to carry
out each of these operations because the longitudinal force necessary to
effect staple firing is
typically on the order of 250 pounds at the staple cartridge. Further, such
staplers do not have any
kind of active compression indicator that would optimizes the force acting
upon the tissue that is
to be stapled so that tissue degradation does not occur.
-
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One hand-powered, intraluminal anastomotic circular stapler is depicted in,
for example, in U.S.
Patent No. 5,104,025 to Main et al., and assigned to Ethicon. As can be seen
most clearly in the exploded
view of FIG. 7 in Main et al., a trocar shaft 22 has a distal indentation 21,
some recesses 28 for aligning
the frocar shaft 22 to serrations 29 in the anvil and, thereby, align the
staples with the anvils 34. A
trocar tip 26 is capable of puncturing through tissue when pressure is applied
thereto. FIGS. 3 to 6
In Main et at show how the circular stapler 10 fimctions to join two pieces of
tissue together. As
the anvil 30 is moved closer to the head 20, interposed tissue- is compressed
therebetween, as
particularly shown in FIGS. 5 and 6. If this tissue is overcompressed, the
surgical stapling
procedure might not succeed. Thus, it is desirable to not exceed the maximum
acceptable tissue
compression force. The interposed tissue can be subject to a range of
acceptable compressing
force during surgery. This range is known and referred to as optimal tissue
compression or OTC,
and is dependant upon the type of tissue being stapled. While the stapler
shown in Main et al.
does have a bar indicator that displays to the user a safe staple-firing
distance between the anvil
and the staple cartridge, it cannot indicate to the user any level of
compressive force being
imparted upon the tissue prior to stapling. It would be desirable to provide
such an indication so
that over-compression of the tissue can be avoided.
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Disclosure of Invention
The invention overcomes the above-noted and other deficiencies of the prior
art by
providing an electric surgical stapling device that is electrically powered to
position the anvil and
stapler cartridge with respect to one another about the tissue to be stapled
and/or cut, to close the
anvil and stapler cartridge with respect to one another, and to fire and
secure the staples at the
tissue (and/or cut the tissue). Further, the electric surgical stapling device
can indicate to the user
user-pre-defined level of compressive force being imparted upon the tissue
prior to firing the
staples. The present invention also provides methods for operating the
electric surgical stapling
device to staple when OTC exists.
An offset-axis configuration for the two anvil and staple firing sub-
assemblies creates a
device that can be sized to comfortably fit into a user's hand. It also
decreases manufacturing
difficulty by removing previously required nested (co-axial) hollow shafts.
With the axis of the
twit sub-assembly being offset from the staple firing sub-assembly, the length
of the threaded rod
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for extending and retracting the anvil can be decreased by approximately two
inches, thereby
saving in manufacturing cost and generating a shorter longitudinal profile.
An exemplary method for using the electric stapler includes a power-on feature
that
permits entry into a manual mode for testing purposes. In a surgical
procedure, the stapler is a
one-way device. In the test mode, however, the user has the ability to move
the trocar back and
forth as desired. This test mode can be disengaged and the stapler reset to
the use mode for
packaging and shipment. For packaging, it is desirable (but not necessary) to
have the anvil be at
a distance from the staple cartridge. Therefore, a homing sequence can be
programmed to place
the anvil 1 cm (for example) away from the staple cartridge before powering
down for packaging
and shipment. Before use, the trocar is extended and the anvil is removed. If
the stapler is being
used to dissect a colon, for example, the trocar is refracted back into the
handle and the handle is
inserted irans-anally into the colon to downstream side of the dissection
While the anvil is inserted
through a laparoscopic incision to an upstream side of the dissection. The
anvil is attached to the
trocar and the two parts are retracted towards the handle until a staple ready
condition occurs. The
staple firing sequence is started, which can be aborted, to staple the
dissection and simultaneously
cut tissue at the center of the dissection to clear an opening in the middle
of the circular ring of
staples. The staple firing sequence includes an optimal tissue compression
(OTC) measurement
and feedback control mechanism that causes staples to be fired only when the
compression is in a
desired pressure range, referred to as the OTC range. This range or value is
known beforehand
based upon known characteristics of the tissue to be compressed between the
anvil and staple
cartridge. =
Some exemplary procedures in which the electric stapler can be used include
colon
dissection and gastric bypass surgeries. There are many other uses for the
electric stapler in
various different technology areas.
With the objects of the invention in view, there is also provided a surgical
instrument,
including a surgical end effector having at least one actuation assembly to
effect a surgical
procedure when actuated, an electric motor operationally connected to the end
effector to operate
the at least one actuation assembly, and a power supply electrically connected
to the motor and
selectively powering the motor to actuate the at least one actuation assembly.
The power supply
has at least one battery cell with a critical current rate. When activated to
power the motor and
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actuate the at least one actuation assembly, the power supply operates the at
least one battery cell
at a super-critical current rate.
With the objects of the invention in view, there is also provided a surgical
instrument,
$ including a surgical end effector having at least one actuation assembly
to effect a surgical
procedure when actuated, an electric motor operationally connected to the end
effector to operate
the at least one actuation assembly, and a power supply electrically connected
to the motor and
selectively powering the motor to actuate the at least one actuation assembly.
The power supply
has at least one battery cell with a critical current rate, and, when
activated to power the motor and
actuate the at least one actuation assembly, the power supply operates the at
least one battery cell
at an average current rate above the critical current rate.
With the objects of the invention in view, there is also provided a surgical
instrument,
including a surgical end effector having at least one actuation assembly to
effect a surgical
procedure when actuated, an electric motor operationally connected to the end
effector to operate
the at least one actuation assembly, and a power supply electrically connected
to the motor and
selectively powering the motor to actuate the at least one actuation assembly
at least 1 and less
than 16 times during a clinical life of at least one of the end effector, the
motor, and the power
supply. The power supply has at least one battery cell that, when activated to
actuate the at least
one actuation assembly, operates only between approximately 0.5 seconds and
approximately 15
seconds in duration. 1
With the objects of the invention in view, there is also provided a surgical
instrument,
including a surgical end effector having at least one actuation assembly to
effect a surgical
procedure when actuated, an electric motor having a rated operating voltage
and being
operationally connected to the end effector to operate the at least one
actuation assembly, and a
power supply electrically connected to the motor and selectively powering the
motor to actuate the
at least one actuation assembly. The power supply has at least one battery
cell with a critical
current rate. When activated to power the motor and actuate the at least one
actuation assembly,
the power supply operates the at least one battery cell at a super-critical
current rate at any time
during at least a portion of a super-critical pulse discharge period and
operates the motor above the
rated operating voltage during the super-critical pulse discharge period.
Other features that are considered as characteristic for the invention are set
forth in the
appended claims.
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Although the invention is illustrated and described herein as embodied in an
electrical
surgical instrument with optimized power supply and drive, it is,
nevertheless, not intended to be
limited to the details shown because various modifications and structural
changes may be made
5 therein without departing &Jul the spirit of the invention and within the
scope and range of
equivalents of the claims.
The construction and method of operation of the invention, however, together
with
additional objects and advantages thereof, will be best understood from the
following description
of specific embodiments when read in connection with the accompanying
drawings.
Brief Description of Drawings
Advantages of embodiments of the present invention will be apparent from the
following
detailed description of the preferred embodiments thereof, which description
should be considered
in conjunction with the ac,companying drawings in which:
FIG. 1 is a perspective view from a side of an exemplary embodiment of an
electric stapler
according to the invention;
FIG. 2 is a fragmentary side elevational view of the stapler of FIG. 1 with a
right half of a
handle body and with a proximal backbone plate removed;
FIG. 3 is an exploded, perspective view of an anvil control assembly of the
stapler of FIG.
1;
P10.4 is an enlarged, fragmentary, exploded, perspective view of the anvil
control
assembly of FIG. 3;
FIG. 5 is a fragmentary, perspective view of a staple firing control assembly
of the stapler
of FIG. 1 from a rear side thereof.; =
FIG. 6 is an exploded, perspective view of the staple firing control assembly
of the stapler
of FIG. 1;
FIG.? is an enlarged, fragmentary, exploded, perspective view of the staple
fixing control
assembly of FIG. 6;
FIG. 8 is a fragmentary, horizontally cross-sectional view of the anvil
control assembly
from below the handle body portion of the stapler of FIG. I;
FIG. 9 is a fragmentary, enlarged, horizontally cross-sectional view from
below a proximal
portion of the anvil control assembly FIG. 8;
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FIG. 10 is a fragmentary, enlarged, horizontally cross-sectional view from
below an
intermediate portion of the anvil control assembly of FIG. 8;
FIG. 11 is a fragmentary, enlarged, horizontally cross-sectional view from
below a distal
portion of the anvil control assembly of FIG. 8;
FIG. 12 is a fragmentary, vertically cross-sectional view from a right side of
a handle body
portion of the stapler of FIG. 1;
FIG. 13 is a fragmentary, enlarged, vertically cross-sectional view from the
right side of a
proximal handle body portion of the stapler of FIG. 12;
FIG. 14 is a fragmentary, enlarged, vertically cross-sectional view from the
right side of an
intermediate handle body portion of the stapler of HQ. 12;
FIG. 15 is a fragmentary, further enlarged, vertically cross-sectional view
from the right
side of the intermediate handle body portion of the stapler of FIG. 14;
FIG. 16 is a fragmentary, enlarged, vertically cross-sectional view from the
right aide of a
distal handle body portion of the stapler of FIG. 12;
FIG. 17 is a perspective view of a portion of an anvil of the stapler of FIG.
1;
FIG. 18 is a fragmentary, cross-sectional view of a removable stapling
assembly including
the anvil, a stapler cartridge, a force switch, and a removable cartridge
connecting assembly of the
stapler of FIG. 1;
FIG. 19 is a fragmentary, horizontally cross-sectional view of the anvil
control assembly
from above the handle body portion of the stapler of FIG. l'with the anvil rod
in a fully extended
position;
FIG. 20 is a fragmentary, side elevational view of the handle body portion of
the stapler of
. FIG. 1 from a left side of the handle body portion with the left
handle body and the circuit board
removed and with the anvil rod in a fully extended position;
FIG. 21 is a fragmentary, side elevational view of the handle body portion of
the stapler of
FIG. 20 with the anvil rod in a 1-cm anvil closure position;
FIG. 22 is a fragmentary, horizontally cross-sectional view of the anvil
control assembly
from above the handle body portion of the stapler of FIG. 1 with the anvil rod
in a safe staple
firing position;
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FIG. 23 is a fragmentary, horizontally cross-sectional view of the anvil
control assembly
from above the handle body portion of the stapler of FIG. 1 with the anvil rod
in a fully retracted
position;
FIG. 24 is a fragmentary, horizontally cross-sectional view of the firing
control assembly
from above the handle body portion of the stapler of FIG. 1;
FIG. 25 is a fragmentary, enlarged, horizontally cross-sectional view from
above a
proximal portion of the firing control assembly of FIG. 24;
FIG. 26 is a fragmentary, enlarged, horizontally cross-sectional view from
above an
intermediate portion of the firing control assembly of FIG. 24;
FM. 27 is a fragmentary, enlarged, horizontally cross-sectional view from
above a distal
portion of the firing control assembly of FIG. 24;
FIGS. 28 and 29 arc shaded, fragmentary, enlarged, partially transparent
perspective views
of a staple cartridge removal assembly of the stapler of FIG. 1;
FIG. 30 is a schematic circuit diagram of an exemplary encryption circuit for
interchangeable parts oldie medical device according to tho invention;
FIG. 31 is a bar graph illustrating a speed that a pinion moves a rack shown
in FIG. 32 for
various loads;
FIG. 32 is a fragmentary, perspective view of a simplified, exemplary portion
of a gear
train according to the present invention between a gear box and a rack;
FIG. 33 is a fragmentary, vertically longitudinal, cross-sectional view of a
distal end of an
articulating portion of an exemplary embodiment of an end effector with the
inner tube, the
pushrod-blade support, the anvil, the closure ring, and the near half of the
staple sled removed;
FIG. 34 is a schematic circuit diagram of an exemplary switching assembly for
a power
supply according to the invention;
FIG. 35 is a schematic circuit diagram of an exemplary switching assembly for
forward
and reverse control of a motor according to the invention; and
FIG. 36 is a schematic circuit diagram of another exemplary switching assembly
for the
power supply and the forward and reverse control of the motor according to the
invention.
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Best Mode for Carrying Out the Invention
Aspects of the invention are disclosed in the following description and
related drawings
directed to specific embodiments of the invention. Alternate embodiments may
be devised
without departing from the spirit or the scope of the invention. Additionally,
well-known elements
of exemplary embodiments of the invention will not be described in detail or
will be omitted so as
not to obscure the relevant details of the invention.
Before the present invention is disclosed and described, it is to be
understood that the
terminology used herein is for the purpose of describing particular
embodiments only and is not =
intended to be limiting. It must be noted that, as used in the specification
and the appended
claims, the singular forms "a," "an," and "the" include plural references
unless the context clearly
dictates otherwise.
While the specification concludes with claims defining the features of the
invention that
are regarded as novel, it is believed that the invention will be better
understood from a
consideration of the following description in conjunction with the drawing
figures, in which like
reference numerals are carried forward. The figures of the drawings are not
drawn to scale.
Further, it is noted that the figures have been created using a computer-aided
design computer
program. This program at times removes certain structural lines and/or
surfaces when switching
from a shaded or colored view to a wfreframe view. Accordingly, the drawings
should be treated
as approximations and be used as illustrative of the features of the present
invention.
Referring now to the figures of the drawings in detail and first, particularly
to FIGS. 1 to 2
thereof, there is shown an exemplary embodiment of an electric surgical
circular stapler 1. The
present application applies the electrically powered handle to a circular
surgical staple head for
ease of understanding only. The invention is not limited to circular staplers
and can be applied to
any surgical stapling head, such as a linear stapling device, for example.
The powered stapler 1 has a handle body 10 containing three switches: an anvil
open
switch 20, an anvil close switch 21, and a staple firing switch 22. Each of
these switches is
electrically connected to a circuit board 500 (see FIG. 12) having circuitry
programmed to carry
out the stapling functions of the stapler I. The circuit board 500 is
electrically connected to a
power supply 600 contained within the handle body 10. One exemplary embodiment
utilizes 2 to
6 Lithium CR123 or CR2 cells as the power supply 600. Other power supply
embodiments are
possible, such as rechargeable batteries or a power converter that is
connected to an electric mains
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(in the latter embodiment, the stapler would not be self-powered or self-
contained). As used
herein, the terms self-powered or self-contained when used with regard to the
electric power
supply (600) are interchangeable and mean that the power supply is a complete
and independent
unit in and of itself and can operate under its own power without the use of
external power
sources. For example, a power supply having an electric cord that is plugged
into an electric
mains during use is not self-powered or self-contained.
Insulated conductive wires or conductor tracks on the circuit board 500
connect all of the
electronic parts of the stapler 1, such as an on/off switch 12, a tissue
compression indicator 14, the
anvil and firing switches 20,21, 22, the circuit board 500, and the power
supply 600, for example.
But these wires and conductors are not shown in the figures of the drawings
for ease of
understanding and clarity.
The distal end of the handle body 10 is connected to a proximal end of a rigid
anvil neck
30. Opposite this connection, at the distal end of the anvil neck 30, is a
coupling device 40 for
removably attaching a staple cartridge 50 and an anvil 60 thereto.
Alternatively, the staple
cartridge 50 can be non-removable in a single-use configuration of the stapler
1. These
connections will be described in further detail below.
FIG. 2 shows the handle body 10 with the right half 13 of the handle body 10
and the
circuit board 500 removed. As will be discussed below, a proximal backbone
plate 70 is also
removed from the view of FIG. 2 to allow viewing of the internal components
inside the handle
body 10 from the right side thereof. What can be seen from the view of FIG. 2
is that there exist
two internal component axes within the handle body 10. A first of these axes
is the staple control
axis 80, which is relatively horizontal in the view of FIG. 2, The staple
control axis 80 is the
centerline on which lie the components for controlling staple actuation. The
second of these axes
is the anvil control axis 90 and is disposed at an angle to the staple control
axis 80. The anvil
control axis 90 is the centerline on which lie the components for controlling
anvil actuation. It is
this separation of axes 80,90 that allows the electric stapler] to be powered
using a handle body
10 that is small enough to fit in a physician's hand and that does not take up
so much space that
the physician becomes restricted from movement in all necessary directions and
orientations.
Shown inside the handle body 10 is the on/off switch 12 (e.g., a grenade pin)
for
controlling power (e.g., battery power) to all of the electrical components
and the tissue
compression indicator 14. The tissue compression indicator 14 indicates to the
physician that the
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tissue being compressed between the anvil 60 and the staple cartridge 50 has
or has not been
compressed with greater than a pre-set compressive force, which will be
described in further detail
below. This indicator 14 is associated with a force switch 400 that has been
described in co-
5 pending U.S. Patent Provisional Application Serial No. 60/801,989 filed
May 19, 2006, and titled
"Force Switch" (the entirety of which is incorporated by reference herein).
The components along the anvil control axis 90 make up the anvil control
assembly 100.
An anvil control frame 110 is aligned along the anvil control axis 90 to house
and/or fix various
part of the anvil control assembly 100 thereto. The anvil control frame 110
has a proximal mount
10 112, an intermediate mount 114, and a distal mount 116. Each of these
mounts 112, 114, 116 can
be attached to or integral with the control frame 110. In the exemplary
embodiment, for ease of
manufacturing, the proximal mount 112 has two halves and is separate from the
frame 110 and the
intermediate mount 114 is separate from the frame 110.
At the proximal end of the anvil control assembly 100 is an anvil motor 120.
The anvil
motor 120 includes the drive motor and any gearbox that would be needed to
convert the native
motor revolution speed to a desired output axle revolution speed. In the
present case, the drive
motor has a native speed of approximately 10,000 rpm and the gearbox converts
the speed down
to between approximately 50 and 70 rpm at an axle 122 extending out from a
distal end of the
anvil motor 120. The anvil motor 120 is secured both longitudinally and
rotationally inside the
proximal mount 112.
A motor-shaft coupler 130 is rotationally fixed to the axle 122 so that
rotation of the axle
122 translates into a corresponding rotation of the motor coupler 130.
Positioned distal of the coupler 130 is a rotating nut assembly 140. The nut
assembly 140
is, in this embodiment, a two part device having a proximal nut half 141 and a
distal nut half 142
rotationally and longitudinally fixed to the proximal nut half 141. It is
noted that these nut halves
141, 142 can be integral if desired. Here, they are illustrated in two halves
for case of
manufacturing. The proximal end of the nut assembly 140 is rotationally fixed
to the distal end of
the coupler 130. Longitudinal and rotational support throughout the length of
these two connected
parts is assisted by the intermediate 114 and distal 116 mounts.
A proximal nut bushing 150 (see FIG. 3) is interposed between the intermediate
mount 114 =
and the proximal nut half 141 and a distal nut bushing 160 is interposed
between the distal mount
116 and the distal nut half 14210 have these parts spin efficiently and
substantially without friction
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within the handle body 10 and the anvil control frame 110. The bushings 150,
160 can be of any
suitable bearing material, for example, they can be of metal such as bronze or
a polymer such as
nylon. To farther decrease the longitudinal friction between the rotating nut
assembly 140 and the
coupler 130, a thrust washer 170 is disposed between the proximal bushing 150
and the proximal
nut half 141.
Rotation of the coupler 130 and nut assembly 140 is used to advance or retract
a threaded
rod 180, which is the mechanism through which the anvil 60 is extended or
retracted. The
threaded rod 180 is shown in further detail in the exploded view of FIGS. 3 to
4 and is described
in further detail below. A rod support 190 is attached to a distal end of the
anvil control frame 110
for extending the supporting surfaces inside the nut assembly 140 that keep
the rod 180 aligned
along the anvil control axis 90. The rod support 190 has a smooth interior
shape corresponding to
an external shape of the portion of the rod 180 that passes therethrough. This
mating of shapes
allows the rod 180 to move proximally and distally through the support 190
substantially without
friction. To improve frictionless movement of the rod 180 through the support
190, in the
exemplary embodiment, a cylindrical rod bushing 192 is disposed between the
support 190 and the
rod 180. The rod bushing 192 is not visible in FIG. 2 because it rests inside
the support 190.
However, the rod bushing 192 is visible in the exploded view of FIGS. 3 to 4.
With the rod
bushing 192 in place, the internal shape of the support 190 corresponds to the
external shape of the
rod bushing 192 and the internal shape of the rod bushing 192 corresponds to
the external shape of
the portion of the rod 180 that passes therethrough. The rod bushing 192 can
be, for example, of
metal such as bronze or a polymer such as nylon.
The components along the staple control axis 80 form the staple control
assembly 200.
The staple control assembly 200 is illustrated in FIG. 5 viewed from a
proximal upper and side
perspective. The proximal end of the staple control assembly 200 includes a
stapling motor 210.
The stapling motor 210 includes the drive motor and any gearbox that would be
needed to convert
the native motor revolution speed to a desired revolution speed. In the
present case, the drive
motor has a native speed of approximately 20,000 rpm and the gearbox converts
the speed to
approximately 200 rpm at an output axle 212 at the distal end of the gearbox.
The axle 212 cannot
be seen in the view of FIG. 5 but can be seen in the exploded view of FIGS. 6
to 7.
The stapling motor 210 is rotationally and longitudinally fixed to a motor
mount 220.
Distal of the motor mount 220 is an intermediate coupling mount 230. This
coupling mount 230
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.=
has a distal plate 232 that is shown, for example in FIG. 6. The distal plate
232 is removable from
1
the coupling mount 230' so that a rotating screw 250 can be held therebetween.
It is this rotating
screw 250 that acts as the drive for ejecting the staples out of the staple
cartridge 50. The
efficiency in transferring the rotational movement of axle 212 to the rotating
screw 250 is a factor
that can substantially decrease the ability of the stapler 1 to deliver the
necessary staple ejection
longitudinal force of up to 250 pounds. Thus, an exemplary embodiment of the
screw 250 has an
acme profile thread.
There are two exemplary ways described herein for efficiently coupling the
rotation of the
axle 212 to the screw 250. First, the stapling motor 210 can be housed
loosely" within a chamber
defined by the handle body 10 so that it is rotationally stable but has play
to move radially and so
that it is longitudinally stable but has play to move. In such a
configuration, the stapling motor
210 will "find its own center" to align the axis of the axle 212 to the axis
of the screw 250, which,
in the exemplary embodiment, is also the staple control axis 80.
A second exemplary embodiment for aligning the axle 212 and the screw 250 is
illustrated
in FIGS. 1 to 5, for example. In this embodiment, a proximal end of a flexible
coupling 240 is
fixed (both rotationally and longitudinally) to the axle 212. This connection
is formed by fitting
the distal end of the axle 212 inside a proximal bore 241 of the flexible
coupling 240. See FIG.
12. The axle 212 is, then, secured therein with a proximal setscrew 213. The
screw 250 has a
proximal extension 251 that fits inside a distal bore 242 of the flexible
coupling 240 and is secured
therein by a distal setscrew 252. It is noted that the figures of the drawings
show the flexible
coupling 240 with ridges in the middle portion thereof. In an exemplary
embodiment of the
coupling 240, the part is of aluminum or molded plastic and has a spiral or
helixed cut-out around
the cizturnference of the center portion thereof. In such a configuration, one
end of the coupling =
240 can move in any radial direction (360 degrees) with respect to the other
end (as in a gimbal),
thus providing the desired flex to efficiently align the central axes of the
axle 212 and the screw
250. = =
The proximal extension 251 of the screw 250 is substantially smaller in
diameter than the
diameter of the bore 231 that exists in and through the intemiediate coupling
mount 230. This
bore 231 has two increasing steps in diameter on the distal side thereof. The
first increasing step
in diameter is sized to fit a proximal radius screw hushing 260, which is
formed of a material that
is softer than the intermediate coupling mount 230. The proximal radius screw
bushing 260 only
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= keeps the screw 250 axially aligned and does not absorb or transmit any
of the longitudinal thrust.
The second increasing step in diameter is sized to fit a proximal thrust
bearing 270 for the screw
250. In an exemplary embodiment of the thrust bearing 270, proximal and distal
plates sandwich a
bearing ball retainer plate and bearing balls therebetween. This thrust
bearing 270 absorbs all of
the longitudinal thrust that is imparted towards the axle 212 while the up to
250 pounds of
longitudinal force is being applied to eject the staples in the staple
cartridge 50. The proximal
extension 251 of the screw 250 has different sized diameters for each of the
interiors of the screw
bushing 260 and the thrust bearing 270. The motor mount 220 and the coupling
mount 230,
therefore, form the two devices that hold the flexible coupling 240
therebetween.
The rotating screw 250 is held inside the distal plate 232 with a distal
radius screw bushing
280 similar to the proximal radius screw bushing 260. Thus, the screw 250
rotates freely within
the distal plate 232. To translate the rotation of the screw 250 into a linear
distal movement, the
screw 250 is threaded within a moving nut 290. Movement of the nut 290 is
limited to the amount
of movement that is needed for complete actuation of the staples; in other
words, the nut 290 only
needs to move through a distance sufficient to form closed staples between the
staple cartridge 50
and the anvil 60 and to extend the cutting blade, if any, within the staple
cartridge 50, and then
retract the same. When the nut 290 is in the proximal-most position (see,
e.g., FIG. 12), the
staples are at rest and ready to be fired. When the nut 290 is in the distal-
most position, the staples
are stapled through and around the tissue interposed between the staple
cartridge 50 and the anvil,
and the knife, if any, is passed entirely through the tissue to be cut. The
distal-most position of the
nut 290 is limited by the location of the distal plate 232. Thus, the
longitudinal length of the
threads of the screw 250 and the location of the distal plate 232 limit the
distal movement of the
nut 290.
Frictional losses between the screw 250 and the nut 290 contribute to a
significant
reduction in the total pounds of force that can be transmitted to the staple
cartridge 50 through the
cartridge plunger 320. Therefore, it is desirable to select the materials of
the screw 250 and the
nut 290 and the pitch of the threads of the screw 250 in an optimized way. It
has been found that
use of a low-friction polymer for manufacturing the nut 290 will decrease the
friction enough to
transmit the approximately 250 pounds of longitudinal force to the distal end
of the cartridge
plunger 320 the amount of force that is needed to effedively deploy the
staples. Two particular
exemplary materials provide the desired characteristics and are referred to in
the art as DELRINO
=
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AF Blend Acetal (a thermoplastic material combining TEFLON fibers uniformly
dispersed in
DELRIN0 acetal resin), and RULON (a compounded form of TFE fluorocarbon) or
other similar
low-friction polymers. =
A nut coupling bracket 300 is longitudinally fixed to the nut 290 so that it
moves along
with the nut 290. The nut coupling bracket 300 provides support for the
relatively soft, lubricious
nut material. In the exemplary embodiment shown, the bracket 300 has an
interior cavity having a
shape corresponding to the exterior shape of the nut 290. Thus, the nut 290
fits snugly into the
coupling bracket 300 and movement of the nut 290 translates into a
corresponding movement of
the nut coupling bracket 300. The shape of the nut coupling bracket 300 is, in
the exemplary
embodiment, dictated by the components surrounding it and by the longitudinal
forces that it has
to bear. For example, there is an interior cavity 302 distal of the nut 290
that is shaped to receive
the distal plate 232 therein. The nut coupling bracket 300 also has a distal
housing 304 for
receiving therein a stiffening rod 310. The stiffening rod 310 increases the
longitudinal support
and forms a portion of the connection between the nut 290 and a cartridge
plunger 320 (see, i.e.,
FIG. 5), which is the last moving link between elements in the handle body 10
and the staple
cartridge 50. A firing bracket 330, disposed between the distal end of the nut
coupling bracket
300 and the stiffening rod 310, strengthens the connection between the nut
coupling bracket 300
and the rod 310.
Various components of the stapler 1 are connected to one another to form a
backbone or =
spine. This backbone is a frame providing multi-directional stability and is
made up of four
primary parts (in order from proximal to distal): the anvil control frame 110,
the proximal
backbone plate 70 (shown in FIGS. 3 to 4 and 6 to 7), a distal backbone plate
340, and the anvil ,=
neck 30. Each of these four parts is longitudinally and rotationally fixed to
one another in this
order and forms the skeleton on which the remainder of the handle components
is attached in some
way. Lateral support to the components is provided by contours on the inside
surfaces of the
handle body 10, which in an exemplary embodiment is formed of two halves, a
left half 11 and a
right half 13. Alternatively, support could be single frame, stamped, or
incorporated into the
handle halves 11, 13.
Functionality of the anvil control assembly 100 is described with regard to
FIGS. 17 to 27.
To carry out a stapling procedure with the stapler 1, the anvil 60 is removed
entirely from the
stapler 1 as shown in FIG. 17. The anvil open switch 20 is depressed to extend
the distal end of
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the trocar tip 410 housed within the staple cartridge and which is
longitudinally fixedly connected
to the screw 250. The point of the trocar tip 410 can, now, be passed through
or punctured
through tissue that is to be stapled. The user can, at this point, replace the
anvil 60 onto the trocar
5 tip 410 from the opposite side of the tissue (see FIG. 18) and, thereby,
lock the anvil 60 thereon.
The anvil closed switch 22 can be actuated to begin closing the anvil 60
against the staple
cartridge 50 and pinch the tissue therebetween within an anvil-cartridge gap
62.
To describe how the trocar tip controlling Movement of the anvil 60 occurs,
reference is
made to FIGS. 8 to 10, 14 to 15, and 18. As shown in dashed lines in FIG. 15,
a rod-guiding pin
10 143 is positioned within the central bore 144 of the distal nut half
142. As the threaded rod 180 is
screwed into the rotating nut 140, 141, 142, the pin 143 catches the proximal
end of the thread 182
to surround the pin 143 therein. Thus, rotation of the nut 140 with the pin
143 inside the thread
182 will cause proximal or distal movement of the rod 180, depending on the
direction of nut
rotation. The thread 182 has a variable pitch, as shown in FIGS. 14 to 15, to
move the anvil 60 at
15 different longitudinal speeds. When the pin 143 is inside the longer
(lower) pitched thread portion
183, the anvil 60 moves longitudinally faster. In comparison, when the pin 143
is inside the
shorter (higher) pitched thread portion 184, the anvil 60 moves longitudinally
slower. It is noted
that the pin 143 is the only portion contacting the thread 182 when in the
longer pitched thread
portion 183. Thus, the pin 143 is exposed to the entire longitudinal force
that is acting on the rod
180 at this point in time. The pin 143 is strong enough to bear such forces
but may not be
sufficient to withstand all longitudinal force that could occur with anvil 60
closure about
interposed tissue.
As shown in FIG. 14, the rod 180 is provided with a shorter pitched thread
portion 184 to
engage in a corresponding internal thread 145 at the proximal end of the
central bore 144 of the
proximal nut half 141. When the shorter pitched thread portion 184 engages the
internal thread
145, the entire transverse surface of the thread portion 184 contacts the
internal thread 145. This
surface contact is much larger than the contact between the pin 143 and any
portion of the thread
182 and, therefore, can withstand all the longitudinal force that occurs with
respect to anvil 60
closure, especially when the anvil 60 is closing about tissue during the
staple firing state. For
example, in the exemplary embodiment, the pin 143 bears up to approximately 30
to 50 pounds of
longitudinal force. This is compared to the threads, which can hold up to 400
pounds of
longitudinal force ¨ an almost 10-to-1 difference.
. _
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An alternative exemplary embodiment of anvil control assembly 100 can entirely
remove
the complex threading of the rod 180. In such a case, the rod 180 has a single
thread pitch and the
anvil motor 120 is driven (through corresponding programming in the circuit
board 500) at
different speeds dependent upon the longitudinal position of the single-thread
rod 180.
In any embodiment for driving the motors 120, 210, the control programming can
take
many forms. In one exemplary embodiment, the micmcontroller on the battery
powered circuit
board 500 can apply pulse modulation (e.g., pulse-width, pulse-frequency) to
drive either or both
of the motors. Further, because the stapler 1 is a device that has a low duty
cycle, or is a one-use
device, components can be driven to exceed acceptable manufacturers'
specifications. For
example, a gear box can be torqued beyond its specified rating. Also, a drive
motor, for example,
a 6 volt motor, can be overpowered, for example, with 12 volts.
= Closure of the anvil 60 from an extended position to a position in which
the tissue is not
compressed or is just slightly compressed can occur rapidly without causing
damage to the
interposed tissue. Thus, the longer-pitched thread portion 183 allows the user
to quickly close the
anvil 60 to the tissue in a tissue pr compressing state. Thereafter, it is
desirable to compress the
tissue slowly so that the user has control to avoid over-compression of the
tissue. As such, the
shorter pitched thread portion 184 is used over this latter range of movement
and provides the user
with a greater degree of control. During such compression, the force switch
400 seen in FIG. 18
and described in co-pending U.S. Patent Provisional Application Serial No.
60/801,989 can be
used to indicate to the User through the tissue compression indicator 14
(and/or to the control
circuitry of the circuit board 500) that the tissue is being compressed with a
force that is roster
than the pre-load of the spring 420 inside the force switch 400. It is noted
that FIG. 18 illustrates
the force switch 400 embodiment in the normally-open configuration described
as the first
exemplary embodiment of U.S. Patent Provisional Application Serial No.
60/801,989. A strain
= gauge can also be used for measuring tissue compression.
FIGS. 19 to 23 illustrate movement of the rod 180 from an anvil-extended
position (see
FIGS. 19 to 20), to a 1-cm-closure-distance position (see FIG. 21), to a
staple-fire-ready position
(see FIG. 22), and, finally, to an anvil fully closed position (see FIG. 23).
Movement of the rod
180 is controlled electrically (via the circuit board 500) by contact between
a portion of a cam
surface actuator 185 on the rod 180 and actuating levers or buttons of a
series of micro-switches
positioned in the handle body 10.
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A rod-fully-extended switch 610 (see FIG. 19) is positioned distal in the
handle body 10 to
have the actuator 185 compress the activation lever of the rod-filly-extended
switch 610 when the
rod 180 (and, thereby, the anvil 60) is in the fully extended position. A I-cm
switch 612 is
positioned in an intermediate position within the handle body 10 (see FIGS. 20
to 21) to prevent a
1-cm cam surface portion 186 of the rod 180 from pressing the activation
button of the 1-cm
switch 612 when the rod 180 (and, thereby, the anvil 60) is within 1 cm of the
fully closed
position. After passing the 1-cm closure distance, as shown in FIG. 22, the
cam surface actuator
185 engages a staple-fire-ready switch 614. The lower end of the actuator 185
as viewed in FIGS.
22 to 23 has a bevel on both the forward and rear sides with respect to the
button of the staple-fire-
ready switch 614 and the distance between the portion on the two bevels that
actuates the button
(or, only the flat portion thereof) corresponds to the acceptable staple
forming range (i.e., safe
firing length) of the staples in the staple cartridge 50. Thus, when the
button of the staple-fire-
ready switch 614 is depressed for the first time, the distance between the
anvil 60 and the staple
cartridge 50 is at the longest range for successfully firing and closing the
staples. While the button
is depressed, the separation distance 62 of the anvil 60 (sec FIG. 18) remains
within a safe staple-
firing range. However, when the button of the staple-fire-ready switch 614 is
no longer depressed
¨ because the actuator 185 is positioned proximally of the button, then
staples will not fire
because the distance is too short for therapeutic stapling. FIG. 23 show the
rod 180 in the
proximal-most position, which is indicated by the top end of the actuator 185
closing the lever of a
rod fully-retracted switch 616. When this switch 616 is actuated, the prop
mutating in the circuit
board 500 prevents the motor 120 from turning in a rod-retraction direction;
in other words, it is a
stop switch for retracting the rod 180 in the proximal direction.
It is noted that FIGS. 2 to 3, 11 to 12, and 16 illustrate the distal end of
the rod 180 not
= being connected to another device at its distal end (which would then
contact the proximal end of
the force switch 400). The connection band or bands between the distal end of
the rod 180 and the
proximal end of the force switch 400 are not shown in the drawings only for
clarity purposes. In
an exemplary embodiment, the pull-bands are flat and flexible to traverse the
curved underside of
the cartridge plunger 320 through the anvil neck 30 and up to the proximal end
of the force switch
400. Of course, if the force switch 400 is not present, the bands would be
connected to the
proximal end of the trocar tip 410 that releasably connects to the proximal
end of the anvil 60.
=
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Functionality of the staple control assembly 200 is described with regard to
FIGS. 12 to 16
and 24 to 27, in particular, to FIG. 24. The stapling motor 210 is held
between a motor bearing
222 and a motor shaft cover 224. The axle 212 of the stapling motor 210 is
rotationally connected
to the proximal end of the flexible coupling 240 and the distal end of the
flexible coupling 240 is
rotationally connected to the proximal end of the screw 250, which rotates on
bearings 260, 270,
280 that are disposed within the intermediate coupling mount 230 and the
distal plate 232. The
longitudinally translating nut 290 is threaded onto the screw 250 between the
coupling mount 230
and the distal plate 232. Therefore, rotation of the axle 212 translates into
a corresponding
rotation of the screw 250.
The nut coupling bracket 300 is longitudinally fixed to the nut 290 and to the
stiffening rod
310 and the firing bracket 330. The firing bracket 330 is longitudinally fixed
to the cartridge
plunger 320, which extends (through a non-illustrated staple driver) up to the
staple cartridge 50
(or to the staples). With such a connection, longitudinal movement of the nut
290 translates into a
corresponding longitudinal movement of the cartridge plunger 320. Accordingly,
when the staple
firing switch 22 is activated, the stapling motor 210 is caused to rotate a
sufficient number of times
so that the staples are completely fired from the staple cartridge 50 (and the
cutting blade, if
present, is extended to completely cut the tissue between the anvil 60 and the
staple cartridge 50).
Programming in the circuitry, as described below, then causes the cartridge
plunger 320 to retract
1
after firing and remove any portion of the staple firing parts and/or the
blade within the staple
cartridge 50 from the anvil-cartridge gap 62.
Control of this stapling movement, again, occurs through micro-switches
connected to the
circuit board 500 through electrical connections, such as wires. A first of
these control switches,
the proximal staple switch 618, controls retraction of the staple control
assembly 200 and defines
the proximal-most position of this assembly 200. To actuate this switch, an
actuation plate 306 is
attached, in an adjustable manner, to a side of the nut coupling bracket 300.
See, e.g., FIGS. 6 and
24. As such, when the nut 290 moves proximally to cause the plate 306 on the
nut coupling
bracket 300 to activate the proximal staple switch 618, power to the stapling
motor 210 is removed
to stop further proximally directed movement of the staple control assembly
200.
30- A second of the switches for controlling movement of the staple control
assembly 200 is
located opposite a distal transverse surface of the stiffening rod.310. See,
e.g. FIG. 27. At this
surface is disposed a longitudinally adjustable cam member 312 that contacts a
distal staple switch
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620. In an exemplary embodiment, the cam member 312 is a screw that is
threaded into a distal
bore of the stiffening rod 310. Accordingly, when the nut 290 moves distally
to cause the cam
member 312 of the stiffening rod 310 to activate the distal staple switch 620,
power to the stapling
motor 210 is removed to stop further distally directed movement of the staple
control assembly
200.
FIGS. 28 and 29 illustrate a removable connection assembly to permit
replacement of a
different staple cartridge 60 on the distal end of the anvil 30.
The proximal-most chamber of the handle body 10 defines a cavity for holding
therein a
power supply 600. This power supply 600 is connected through the circuit board
500 to the
motors 120,210 and to the other electrical components of the stapler 1.
The electronic components of the stapler 1 have been described in general with
respect to
control through the circuit board 500. The electric stapler 1 includes, as set
forth above in an
exemplary embodiment, two drive motors 120,210 powered by batteries and
controlled through
pushbuttons 20, 21, 22. The ranges of travel of each motor 120,210 are
controlled by limit
switches 610, 616, 618,620 at the ends of travel and at intermediary locations
612,614 along the
travel. The logic by which the motors 120,210 are controlled can be
accomplished in several
ways. For example, relay, or ladder logic, can be used to define the control
algorithm for the
motors 120,210 and switches 610, 612, 614, 616, 618, 620. Such a configuration
is a simple but
limited control method. A more flexible method employs a microprocessor-based
control system
that senses switch inputs, locks switches out, activates indicator lights,
records data, provides
audible feedback, drives a visual display, queries identification devices
(e.g., radio frequency
identification devices (RFIDs) or cryptographic identification device,$),
senses forces,
communicates with external devices, monitors battery life, etc. The
microprocessor can be part of
an integrated circuit constructed specifically for the purpose of interfacing
with and controlling
complex electro-mechanical systems. Examples of such chips include those
offered by Atmel,
such as the Mega 128, and by PIC, such as the PIC I6F684.
A software program is required to provide control instructions to such a
processor. Once
fully developed, the program can be written to the processor and stored
indefinitely. Such a
system makes changes to the control algorithm relatively simple; changes to
the software that are
uploaded to the processor adjust the control and user interface without
changing the wiring or
mechanical layout of the device.
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For a disposable device, a power-on event is a one time occurrence. In this
case, the
power-on can be accomplished by pulling a tab or a release that is permanently
removed from the
device. The removal enables battery contact, thus powering on the device.
5 In any
embodiment of the device, when the device is powered on, the control program
begins to execute and, prior to enabling the device for use, goes through a
routine that ensures
awareness of actual positions of the extend/retract and firing sub-assemblies,
ieferred to as a
homing routine. The homing routine may be executed at the manufacturer prior
to shipping to The
user. In such a case, the homing routine is performed, the positions of the
assemblies are set, and
10 the device is shipped to the user in a ready-to-use condition. Upon
power-up, the device verifies
its positions and is ready to use.
Visual indicators (e.g., LEDs) arc used to provide feedback to the user. In
the case of the
pushbutton switches 20, 21, 22, they can be lit (or backlit) when active and
unlit when not active. =
The indicators can blink to convey additional information to the user. In the
case of a delayed
15 response after a button press, a given light can blink at an ever-
increasing rate as the response
becomes imminent, for example. The indicators can also light with different
colors to indicate
various states.
Cams are used in various locations at the stapler 1 to activate limit switches
that provide .
position information to the processor. By using linear cams of various
lengths, position ranges can
20 be set. Alternatively, encoders can be used instead of limit switches
(absolute and incremental
positioning). Limit switches are binary: off or on. Instead of binary input
for position
information, encoders (such as optical encoders) can be used to provide
position information.
Another way to provide position feedback includes mounting pulse generators on
the end of the
motors that drive the sub-assemblies. By counting pulses, and by knowing the
ratio of motor turns
to linear travel, absolute position can be derived.
Use of a processor creates the ability to store data. For example, vital, pre-
loaded
information, such as the device serial number and software revision can be
stored. Memory can
also be used to record data while the stapler 1 is in use. Every button press,
every limit switch
transition, every aborted fire, every completed fire, etc., can be stored for
later retrieval and
diagnosis. Data can be retrieved through a programming port or wirelessly. In
an exemplary
embodiment, the device can be put into diagnostic mode through a series of
button presses. In this
diagnostic mode, a technician can query the stapler 1 for certain data or to
transmit/output certain
=
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data. Response from the stapler 1 to such a query can be in the form of
blinking LEDs, or, in the
MSC of a device with a display, visual character data, or can be electronic
data. As set forth above,
a strain gauge can be used for analog output and to provide an acceptable
strain band.
Alternatively, addition of a second spring and support components can set this
band mechanically.
An exemplary control algorithm for a single fire stapler I can include the
following steps:
o Power on.
= o Verify home position and go to home position, if
necessary/desired.
o Enable extend/retract buttons (lit) and disable (unlit) staple fire
button.
o Enable staple fire button only after full extension (anvil removal) and
subsequent retraction with extend/retract buttons remaining enabled.
o Upon actuation of staple fire button, retract anvil until force switch is
activated.
o Begin countdown by blinking fire button LED and increase blink rate as
firing cycle becomes imminent Continue monitoring of force switch and
retract anvil so that force switch remains activated.
o During staple fire cycle, any button press aborts staple fire routine.
o If abort occurs before staple firing motor is activated, firing cycle
stops,
anvil is extended to home position, and staple fire button remains active and
ready for a re-fire.
o Alternatively, if the abort occurs during movement of firing motor,
firing
- cycle stops, firing motor is retracted, anvil is returned to home
position, and
firing button is rendered inactive. Accordingly, stapler (or that staple
cartridge) cannot be used. =
o After countdown to fire is complete, staple range limit switch is queried
for
position. If sterile range limit switch is activated ¨ meaning that anvil is
within an acceptable staple firing range -- then staple firing motor is
activated and firing cycle proceeds. If staple range limit switch is not
activated, then firing cycle is aborted, anvil is returned to home position,
and
staple firing button remains active ready for arc-fire attempt.
o After a completed staple firing, anvil remains in closed position and
only the
extend button remains active. Once anvil is extended to at least the home
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position, both extend and retract buttons are made active. Staple fire button
remains inactive after a completed staple firing.
Throughout the above exemplary cycle, button presses, switch positions,
aborts, and/or fires can
be recorded.
In a surgical procedure, the stapler is a one-way device. In the test mode,
however, the test
user needs to have the ability to move the tracer 410 and anvil 60 back and
forth as desired. The
power-on feature permits entry by the user into a manual mode for testing
purposes. This test
mode can be disengaged and the stapler reset to the use mode for packaging and
shipment
For packaging, it is desirable (but not necessary) to have the anvil 60 be
disposed at a
distance from the staple cartridge 50. Therefore, a homing sequence can be
programmed to place
the anvil 60 one centimeter (for example) away from the staple cartridge 50
before powering down
for packaging and shipment
When the electric stapler is unpacicaged and ready to be used for surgery, the
user tarns the
stapler on (switch 12). Staples should not be allowed to fire at any time
prior to being in a proper
staple-firing position and a desired tissue compression state. Thus, the
anvil/tracar extend/retract
function is the only function that is enabled. In this state, the extend and
retract buttons 20,21 are
lit and the staple firing switch 22 is not lit (i.e., disabled).
Before use inside the patient, the tracer 410 is extended and the anvil 60 is
removed. If the
stapler is being used to anastomose a colon, for example, the trocar 410 is
retracted back into the
anvil neck 30 and the staple cartridge 50 and anvil neck 30 are inserted trans-
anally into the colon
to a downstream side of the dissection. The anvil 60, in contrast, is inserted
through an upstream
laparoscopic incision and placed at the upstream side of the dissection. The
anvil 60 is attached to
the tmcar 410 and the two parts are retracted towards the staple cartridge 50
until a staple ready
condition occurs. As set forth above, the anvil is moved to a distance that
does not substantially
compress and, specifically, does not desiccate, the tissue therebetween. At
this point, staple firing
can occur when desired.
The staple firing sequence is started by activating the staple fire switch 22.
Staple firing
can be aborted anytime during the firing sequence, whether prior to movement
(during the
blanching cycle) or during movement (whether the staples have started to form
or not). The
software is programmed to begin a staple firing countdown sequence because it
is understood that
=
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the tissue needs to be compressed and allowed to desiccate before staple
firing should occur.
Thus, after the staple firing switch 22 is activated, the anvil 60 doses upon
the interposed tissue
and begins to compress the tissue. The staple firing sequence includes an
optimal tissue
compression (OTC) measurement and a feedback control mechanism that causes
staples to be
fired only when the compression is in a 'desired pressure range, referred to
as the OTC range, and a
sufficient time period has elapsed to allow fluid removal from the compressed
tissue. The OTC
range is known beforehand based upon known characteristics of the tissue that
is to be compressed
between the anvil 60 and the staple cartridge 50 (the force switch can be
tuned for different tissue
OTC ranges). It is the force switch 400 that provides the OTC measurement and
supplies the
microprocessor with information indicating that the OTC for that particular
tissue has been
reached. The OTC state can be indicated to the user with an LED, for example.
When the firing sequence begins, the staple fire switch 22 can be made to
blink at a given
rate and then proceed to blink faster and faster, for example, until firing
occurs. If no abort is
triggered during this wait time, the OTC state will remain for the
preprogrammed desiccation
duration and staple filing will occur after the countdown concludes. In the
example of colon
anastomosis with a circular stapler, stapling of the dissection occurs
simultaneously with a cutting
of tissue at the center of the dissection. This cutting guarantees a clear
opening in the middle of
the circular ring of staples sufficient to create an opening for normal colon
behavior after the
surgery is concluded.
As the liquid from the interposed compressed tissue is removed, the
compressive force on
the tissue naturally reduces. In some instances, this reduction can be outside
the OTC range.
Therefore, the program includes closed-loop anvil-compression control that is
dependent upon
continuous measurements provided by the force switch 400. With this feedback,
the compressed
tissue is kept within the OTC range throughout the procedure and even after
being desiccated.
During the staple firing cycle, any actuation of a control switch by the user
can be
programmed to abort the staple fire routine. If an abort occurs before the
staple firing motor 210
is activated, the firing cycle stops, the anvil 60 is extended to a home
position, and the staple fire
switch 22 remains active and ready for a re-fire attempt, if desired.
Alternatively, if the abort
occurs during movement of the staple firing motor 210, the firing cycle stops
and the staple firing
motor 210 is caused to extend the anvil 60 to its home position. At. this
point, the staple firing
=
_
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switch 22 is rendered inactive. Accordingly, the stapler (or that particular
staple cartridge) can no
longer be used (unless the staple cartridge is replaced).
It is noted that before a staple firing can occur, a staple range limit switch
is queried for
relative position of the staple cartridge 50 and anvil 60. If the staple range
limit switch is activated
¨ meaning that anvil 60 is within an acceptable staple firing range ¨ then the
staple firing motor
210 can be made active and the firing cycle can be allowed to proceed. If the
staple range limit
switch is not activated, then the firing cycle is aborted, the anvil 60 is
returned to the home
position, and the staple firing switch 22 remains active and ready for a re-
fire attempt.
Powering (also referred to as actuating, powering, controlling, or activating)
of the motor
and/or the drive train of any portion of the end effector (e.g., anvil or
stapler/cutter) is described
herein.. It is to be understood that such powering need not be limited to a
single press of an
actuation button by the -user nor is the powering of a motor limited to a
single energizing of the
motor by the power supply. Control of any motor in the device can require the
user to puss an
actuation button a number of times, for example, a first time to actuate a
portion of the end
effector for a first third of movement, a second time for a second third of
movement, and a third
time for a last third of movement More specifically for a surgical stapler, a
first exemplary
actuation can move the staple sled or blade past the lock-out, a second
exemplary actuation can
move the part up to the tissue, and a third exemplary actuation can move the
sled past all staples to .
the end of the staple cartridge. Similarly, powering of a motor need not be
constant, for example,
where the motor is energized constantly from the time that the blade begins
movement until it
reaches the end point of its movement. Instead, the motor can be operated in a
pulsed mode, a first
example of which includes periodically switching on And off the power supplied
by the power
supply to the motor during actuation of an end effector function. More
specifically for a stapler,
the motor can be pulsed ten times/second as the staple/cutter moves from its
proximal/start
position to its distal-most position. This pulsing can be directly controlled
or controlled by
microprocessor, either of which can have an adjustable pulse rate.
Alternatively, or additionally,
the motor can be operated with a pulse modulation (pulse-width or pulse-
frequency), with pulses
occurring at very short time periods (e.g., tenths, hundredths, thousandths,
or millionths of a
second). Accordingly, when the power supply, the motor, and/or the drive train
are described
herein as being powered, any of these and other possible modes of operation
are envisioned and
included. =
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After a completed staple firing, the anvil 60 remains in the closed position
and only the
extend switch 20 re:mains active (all other switches are deactivated). Once
the anvil 6013
extended to at least the home position, both the extend and retract switches
20,21 are made active
5 but the retraction switch 21 does not permit closure of the anvil 60 past
the home position. The
staple fire switch 22 remains inactive after a completed staple firing.
As set forth above, the anvil neck 30 houses a linear force switch 400
connected to the
trocar 410. This switch 400 is calibrated to activate when a given tensile
load is applied. The
given load is set to correspond to a desired pressure that is to be applied to
the particular tissue
10 before stapling can occur. Interfacing this switch 400 with the
processor can ensure that the firing
of staples only occurs within the OTC range.
The following text is an exemplary embodiment of a program listing for
carrying out the
methods according to the invention as described herein. The text that follows
is only submitted as
exemplary and those of slalI in the art can appreciate that programming the
methods according to
15 the invention can take many different forms to achieve the same
frmctionality.
'Circular Stapler Program using the rev 3c board (cb280 ehipset) V8.03 (CS-3c-
080306.CUL)
'8-3-06
'Modified program to abort with only fire button, added pbcount variable
20 'Added PWM ramping =
'7-28-06
'final tweaks - sten is now an integer etc.
'7-17-06 This version written for the 3c board.
1-14 DEBUGGING VERSION
25 'Program written for 3c board using the Cubloc 280 chipset
'Note: this program is a modified version of the ones noted below. All changes
not related to the
addition of the E/R limit switches
'apply. The programs below were written to deal with the "gray logic" of the I
cm switch. This
version uses
'a limit switch at either end of the extend/retract stage.
1/6.20 Final Version of Gray Logic program as used in prototype 0, serial
number 100
'V6.05
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'modi6ed the extend to cm 1 and retract to cm 1 routines to make sure that
when they are called
that they move the motor until the cm
'switch is closed; ie: When the anvil is all the way out and the retract
button is pressed, retract the
anvil until the cm limit switch =
'is closed regardless of whether the retract button is released before the cm
switch is closed. Same
change for when the anvil is
'extended from the 1 cm position.
'made changes to comments in the extend/retract routines
cV6.02
'added loop requiring the release of both buttons to exit jog routine, and a 1
second delay at the
end of jog subroutine before
'going back to main routine
'reformatted datadump labels
'added variables for high and low speed pwm values
'added extend only capability at end of completed fire to prevent crushing
stapled tissue
'NOT WORKING- REMOVED added checks To ensure 1 cm switch Is made when
extending Or
retracting from the 1 cm And fully extended positions respectively
'V6.01
'All prior versions were made for testing the program on the Cubloo
development board. All
outputs were pulled LOW. The actual device
'requires all the outputs to be pulled high (+5V). This version is set-up to
run an the actual device.
'limited the values of the EEPROM data to 255 max
'added delays before changes in motor direction, made program run smoother
'removed pwmoff commands. They were not allowing the motors to stay on when
changing
subroutines (for some reason)
'V5.27
'added the recording ofjog routine button presses
'added the recording of datachunp requests
'V5.26
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'added the recording of Extend/Retract button presses
'added serial number field in eeprom
'the datadump routine now keeps running total of data as it is read from
eeprom
`V5.25 (circular-stapler-5-25.cul)
'added code to allow storage of data each power on cycle in eeprom
1/5_24 works well, no known bugs (circular-stapler-5-24.cul)
'ICMS Medical LLC (c) 2006
'MAP
T10 Extend Button
T11 Retract Button
T12 Fire Button
T13 Extend Limit
T14 Retract Limit
'P15 Fire Forward Limit
T16 Fire Back Limit
=
P17 1 cm Limit Switch
T18 Staple Range Limit Switch
T19 Force Switch
P20 Extend Button LED
'P21 Retract Button LED
P22 Fire Button LED
P23 Force LED (blue)
P24 Not USED
T25 Not USED
T26 Not USED
'P27 Not USED
'P28 Not USED
P29 Staple Range LED (green)
=
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amst Device¨c132.80 'Comfile Tech. CubIce CB280 chipset
Dim ver As String*7
ver="3C-8.03" 'set software version here
Dim exteadbutton As Byte
Dim retractbutton As Byte
Dim firebutton As Byte
Dim firstout As Byte
Dim firstback As Byte
Dim cmstatus As Byte '1 ern limit switch status
Dim srstatus As Byte 'staplerange limit switch status
Dim x As Integer
Dim powerons As Byte 'store in eeprom address 2
Dim cycnumfires As Byte 'store in eeprom (powerons*5)
Dim cycabortfires As Byte 'store in eeprom (powerons*5)+1
Dim cycers As Byte 'store in eeprom, number of cycle extend/retract presses
Dim cycjogs As Byte
Dim arm As Byte
Dim completefire As Byte
Dim staplerangestatus As Byte
Dim bail As Byte
Dim ds As Integer 'eeprom data start location for individual cycle data
writing
Dim fast As Integer
Dim slow As Integer
Dim extendonly As Byte
Dim extlirnit As Byte
Dim retlimit As Byte
Dim speed As Integer
Dim dracula As Byte
'initalize outputs
=
=
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Out 20,0 'extend button LED
Out 21,0 'retract button led
Out 22,0 'fire button led
Out 23,0 'force led
Out 29,0 'staple range led
'initialize variables
firstout=0 ,
firstback-A
completefire=0
arm3
cycnumfires
cycabortfires=0
cycers=0
criogs=0
extendonly=0 =
'CHANGE PWM VALUES HERE .
fast=60000 'highspeed pwm value
slow=60000 lowspeed pwm value
speed=0
Output 5 'turns on pwm, output for PINCH
Output 6 'turns on pwm output for FIRE
'read totals from eeprom
poweroneread(2,1)
liter powerons 'increment total power on number
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If powerons>=255 Then powerons=255 limit number of recorded powerons to an
integer of one
byte max
Eewrite 2,powerons,1 'write total power on numberto eepnam
5 ds=powerons*5
=
'JOG and DATADUMP Check
'push any button within 2 (or so) seconds to go to jog routine
'hold all three buttons on at startup to dump the data
10 For x=-1 To 50
If Keyin(10,20)=0 And Keyin(11,20)=0 And Keyin(12,20)=0 Then
datadump 'write all stored data to the debug screen
Exit For
Elseif Keyin(10,20)=0 Or ICeyin(11,20)=0 Or ICeyin(12,20)=0 Then 'either dr
button or
15 the fire button pressed
jog
Exit For
End If
Delay 20
20 Next
'HOMING SEQUENCES
'---------
25 cmstatus=Keyin(17,20) 'read the status of the lcm limit switch
If cmstatus=0 Then
=
homeretract
Elseif cmstatus=1 Then
30 homeextend
End If
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Return fire motor to back position
homefire 'this returns the fire motor to the full retracted condition (P6
limit switch)
3******************************************************************************
**********
'Main Loop
**********
Do
Debug "Main Loop",Cr
Delay 1000
cmstatus=Keyin(17,20) 'read the 1 cm switch
'staplerangestatuKeyin(5,20) 'read the staplerange limit switch
extendbuttonr-Keyin(10,20)
retractbutton=Keyin(11,20)
firebutton=Keyin(12,20)
If cmstatus=0 And Keyin(13,20)<>0 Then
Out 20,1 'turn extend led on
Out 21,1 'turn retract led on
Elseif cmstatus=0 And Keyin(13,20)=0 Then
Out 20,0 'turn off extend led because extend limit met
Out 21,1 lturn on retract limit
Elseif cmstatus=1 Then
Out 20,1
Out 21,0
End If
=
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'check firebutton led status
If firstout=1 And firstbacic=1 And arm=1 And completefire<>1 And cmstatus<>0
Then
Out 22,I 'turn on fire button led
Else =
Out 22,0 'tarn off fire led =
End If
'check for extend retract button press
If extendbutton4J And cmstatus-0 Then
extend
Elseif cmstatul And extendbutton=0 Then
extend ,
End If
If retractbutton=0 And anstatus=43 Then 'And extendonly4
retract
End If
'check for firebutton press
If firebutton=0 And firstout=1 And firstback=1 And arm=1 And completefire<>1
And
cmstaturc>0 Then initialfire
Loop 'keep looping til powerdown
=
End 'End of program
'
SUBROUTINES
=
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,*******************************************************=****************
=
'HOME: retract to cm switch.---not pressed
Sub homeretractO 'retract until 1 cm switch is open
Debug "Homeretrace,Cr
Delay 1000
Pwm 0,slow,60000
Do Until Keyin(17,20)-1 'retract until 1 cm switch is open
Out 31,1 'ER motor reverse
Loop .
Out 31,0 ler motor off
Out 21,0 'turn retract led Off
Out 20,1 'turn extend led On
Pwmoff 0 'turn pwm off
, End Sub
'
'HOME: extend to cm switch¨Tressed
Sub homeextendO 'extend until 1 cm switch is closed
Debug "Homextend",Cr
'Delay 1000
Pwm 0,slow,60000
If Keyin(17,20)=1 Then
Do Until ICeyin(17,20)=0 now the 1 cm switch is pressed
Out 30,1 'ER motor forward DDD
Loop
End If
=
1
=
111
1
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Out 30,0 DDD
Pwmoff 0
Delay 300
homeretract 'once the switch is made, call homeretract
End Sub
'Fire motor homing routine
Sub homefireo
'Debug "Homefire",Cr
'Delay 1000
Pwm 1,slow,60000
Do Until Keyin(16,20)=0 'retract firing stage until back switch is closed
Out 33,1
Loop
Out 33,0
Pwmoff 1
=
End Sub
'JOG Routine
Sub j og0
Out 20,1
Out 21,1
Do
Delay 25
=
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If Keyin(10,20)=0 And Keyiu(1 1,20)=O Then Exit Do if both buttons pressed,
exit jog
routine and start homing routine after 1 second delay
5 If Keyin(10,20)41 And Keyin(11,20)<>0 And Keyin(12,20)<>0 Then
Pwm 0,slow,60000
'Out 30,1 'extend motor forward
Do Until Keyin(10,20)<>0 Or Keyin(13,20)-0
Out 30,1 'extend motor on forward DDD
10 Loop
Out 30,0 'extend motor off forward DDD
Pwmoff 0
Incr cycjogs
If cycjogs>=255 Then cycjogs=255
15 Eewrite ds+3,cycjogs,1
. End If
If Keyin(l I,20)0 And Keyin(10,20)<>0 And Keyin(12,20)<>0 Then
PW121 0,slow,60000
20 Do Until Keyin(11,20)<>0 Or Keyin(14,200
Out 31,1 'extend motor reverse
Loop
Out 31,0 'extend motor off reverse
Pwmoff 0
25 Incr cycjogs
If cycjogs>=255 Then cycjogs...255
Eevvrite ds+3,cycjogs,1
End If
30 If Keyin(12,20)=0 And Keyin(10,20)=0 Then 'jog the fire motor forward
Pwm 1,slow,60000
Do Until Keyin(10,20)<>0 Or KeyiX12,20)<>0 Or Keyin(15,20)=0
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Out 32,1 'fire motor forward
Loop
Out 32,0 Tire motor off forward
Pwmoff 1
Incr cycjogs
If cycjogs>=255 Then cycjogs=255
Eewrite ds+3,cycjogs,1
End If
If Keyin(12,20)=0 And Keyin(11,20)=0 Then log the fire motor reverse
Pwm 1,slow,60000
Do Until Keyin(11,20)<>0 Or Keyin(12,20)<>0 Or Keyin.(16,200
Out 33,1 'fire motor reverse
Loop
Out 33,0 'fire motor off reverse
Pwmoff 1
Jncrcycjogs
If cycjogs>=255 Then cycjogs=255
Eewrite ds+3,cycjogs,1
End If =
Loop
Do Until Keyin(10,201 And Keyin(11,20)=1 'let off both buttons before exiting
jog routine
Delay 10
Loop
Out 20,0 'turn on dr button leds
Out 21,0
Delay 1000
End Sub
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=
=
'Extend until extend limit is met
Sub extend
Out 22,0 'turn off fire button led while extending
Out 21,0 'turn off retract button led while extending
PW111 018460000
Do Until Keyin(I0,20)=1 Or Keyin(13,20),--0 'extend until either the extend
limit is closed or the
extend button is released
Out 30,1 'ER motor forward DDD
Loop
Out 30,0 DDD =
If firstout- Then 'this will keep the extend motor going on the first
extension until the anvil is
all the way out
Do Until Keyin(13,20)=0
Out 30,1 DDD
Loop
Fad If
Out 30,0 DDD
Pwmoff 0
bur years
____ If cycers>= 255 Then eyeers=---255
Eewrite ds+2,cycers,1
If Keyin(13,20)=0 Then =
fustout=1 'set the firstout flag to enable fire button
Out 20,0 'turnoff extend led
End If
End Sub
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'Retract until cm switch is open
Sub retract()
Out 22,0 'turn off fire button led while retracting
Out 20,0 'turn off extend button led while retracting
J.
Pwm 0,fast,60000
Do Until Keyin(11,20)=1 Or Keyin(17,20)=.1 'retract until either the lcrn
switch goes open or the
extend button is released
Out 31,1 'ER motor reverse
Loop
Out 31,0
Pwmoff 0
Incr cycers
If cycers>=255 Then cycer255
Eewrite ds+2,cycers,1 =
If Keyin(17,20)=1 Then
firstback=1
Out 21,0 hut retract led off
End If
If firstout=1 And firstbacic=1 Then ann=1 'set the arm flag to arm the fire
button
End Sub
- -
'DATADUMP Routine
Sub datadumPO
Dim chef As Byte
Dim tf As Byte 'total fires
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Dim ta As Byte 'total aborts
Dim ers As Integer
Dim tj As Byte
Dim tdd As Byte
Dim sten As Integer
Dim kyle As Byte
Dim token As Byte
Dim ike As Byte
Dint kenny As Byto
Dim sn As Byte
tH)
ta=0
ers--0
tdd.-0
Eewrite ds+4,1,1 'write 1 to the ds+4 eeprom register denoting that datadump
was accessed
Delay 1000
sm¨Eere-ad(0,1)
Debug "Circular Stapler Stored Data",Cr
Debug "Version ",ver,Cr
Debug "ICUS Medical LLC",Cr
Debug "----------------------",Cr
Debug Cr
Debug "Serial Number: ",Dec sm,Cr
powerons=Eeread(2,1)
If powerons>=255 Then powerons-255
Debug "Total Cycles: ",Dec powerons,Cr
Debug Cr
Debug
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Debug Cr
For stan=5 To (powerons*5) Step 5
Debug 'Cycle ",Dec (stan/5),Cr
5 Debug "--------------",Cr
chef¨Eeread(stan,l)
tf--chef+tf
Debug "Completed Fires: ",Dec clietCr
kyle=Eeread(stan+1,1)
10 ta=kyle+ta
Debug "Aborted Fires: ",Dec kyle,Cr
token=Beread(stan+2,1)
ers=token+ers
Debug '1E/Rs: ",Dec token,Cr
15 ike=Eeread(stan+34)
tj=ike+tj
Debug "Jogs: ",Dec ike,Cr
kenny=Eeread(stan-4,4,1)
tdd=kenny+tdd
20 Debug "Datadumps: ",Dec kenny,Cr
Debug Cr
Next 'sten
Debug "--------------",Cr
2S Debug "Cycle Totale,Cr
Debug Cr
Debug "Completed Fires: ÷,Dec tf,Cr
Debug "Aborted Fires: ",Dec ta,Cr
Debug "E/R Presses: ",Dec ers,Cr
30 Debug "Jog Presses: ",Dec tj,Cr
Debug "Datadumps: ",Dec tdd,Cr
Debug Cr
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Delay 1000
For x=1 To if blink the number of completed firing cycles
Out 22,1
Delay 500
Out 22,0
Delay 500
Next 'x
Do Until Adin(0)>800 And Keyin(3,20)=1 'wait until datadump buttons are
released
Loop
End Sub
'Initial fire
Sub initialfire()
Dim f As Integer
Dim p As Integer
Dim t As Integer
Dim y As Integer
Dim z As Integer
Dim q As Integer
Dim tiramy As Integer
Dim butter As Integer
Dim numblinks As Integer
Dim fbcount As Integer
Debug clr,Cr
'turn off extend and retract buttons to show that they are not active for
abort?
Out 20,0 'extend button.
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Out 21,0 'retract button
bailO
t=15 'total blink time =
p=3 'number of blink periods
Pwrn 0,fast,60000
'start blink and adjust pinch motor to force
1(t*1000)/p
fbcount=0
If Keyin(12,20)=1 Then fbcount=1
For y=1 Top
numblinks= (t*y)/p
For z...1 To numblinks
timmy=f/numblinks
butter=timmy/50 'calibrate this to seconds
= If timm3=0 Then timmy=1
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
Exit For
End If
If Keyin(12,20)=1 Then fbcount=1
Do Until Keyin(19,20)-Or Keyin(14,20)=0 'retract until
force switch met or retract limit met
Out 31,1
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
Exit Do
=
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End If.
If Keyin(12,20)=1 Then fbcount=1
Loop
If bai1=1 Then Exit For
Out 31,0
Out 23,1 'force led
Out 22,1 'fire button led
For q=0 To butter
Delay 10
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
Exit For
Endif=
If Keyin(12,20)=1 Then fbcount=1
If Keyin(19,201 Then Out 23,0
Next 'q
If bail=1 Then Exit For
Do Until Keyin(19,20)=0 Or Keyin(14,20)=0 'retract until force switch met
or retract limit met
Out 31,1
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
Exit Do
End If
If Keyin(12,201 Then fbcount=1
Loop
Out 31,0
Out 23,1
If Keyin(12,20)=0 And fboount=1 Then
bail=1 'set abortfire flag =
1
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Exit For
End If
If ICeyin(12,201 Then fbcount=1
Out 22,0
For q=0 To butter
Delay 10
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
Exit For
End If
If Keyin(12,20)=1 Then fboount-1
If Keyin(19,201 Then Out 23,0
Next 'q
If bail=1 Then Exit For
Next 'z
Debug Dec? fbcount,Cr
If bail=1 Then Exit For
Next 'y
Pwmoff
If bail=1 Then
abortfire
Else
Istaplerangecheck
finalfire
End If
End Sub
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'Staple Range Check Routine
=
5 Sub staplerangecheck0
srstatusKeyhi.(29,20) 'read the staplerange limit switch
If srstatu.0 Then
finalfire
Else
10 abortfire
End If
End Sub
15 'Final Fire Routine
Sub fmaifire0
Out 23,0 'turn force led off
20 Out 20,0 'turn extend led off
Out 21,0 'tum retract led off
Out 22,1 'rum on fire led to signify final fire abort ready
Pwmoff 1
Twm 1,fast,60000
25 'Out 32,1 'fire motor forward DDD
completefirl
Do Until Keyin(15,200 'fire lanyard until forward limit is met
If speed>50000 Then speed=60000
If speed<60000 Then
30 speed=speed+10000
End If
Pwm 1,speed,60000
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Out 32,1
Delay 50
If Keyin(12,20)- Then 'Or Keyin(10,200 Or Keyin(11,20)=0
bail=1
Exit Do
End If
Loop
Out 32,0 'fire motor fwd off DDD
speed
Delay 250
Do Until Keyin(16,20)4 'retract fire motor
If speed>=60000 Then speed=60000
If speed<60000 Then
speed=speod+10000
End If
Pwm 1,speed,60000
Out 33,1
Delay 50
Loop
speed=0
Out 33,0
Pwmoff 1
Out 22,0 'turn fire led off
Out 21,0 'turn off retract led =
extendonly-=1
Incr cycnumfires
If cycnumfires>=255 Then cycnumfires=255
Eewrite ds,cycnumfires,1 'write the current cycle number of fires to the
ecprom
Delay 200
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End Sub 'return to the main routine
====== =
'Abort fire
Sub abortfireo
'Debug "Fire aborted before fningt!",Or
Out 31,0 'turn retract motor off
Out 32,0 'turn fire forward off DDD
Out 23,0 'turn force led off
Pwm 1,fast,60000
Delay 250
Do Until Keyin(16,200 'retract fire motor
Out 33,1
Loop
Out 33,0
Pwmoff 1
Out 22,0 turn fire led off
Incr cycabortfires
If cycabortfires>=255 Then cycabortfires=255
Rewrite ds+1,cycabortfires,1 'write the current cycle abortfires to the veprom
Delay 200
homeextend 'extend to 1cm
End Sub
Also mentioned above is the possibility of using identification devices with
removable
and/or interchangeable portions of the end effector. Such identification
devices, for example, can
be used to track usage and inventory.
One exemplary identification device employs radio-frequency and is referred to
as an
RFID. In an exemplary embodiment where a medical stapler uses re4oadable,
interchangeable
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staple cartridges, such as the stapler I described herein, an RFID can be
placed in the staple
cartridge to ensure compatibility with the particular stapler and an RFID
reader for sensing
compatible staple cartridges can be associated with the handle. In such a
configuration, the reader
interrogates the RFID mounted in the cartridge. The RFID responds with a
unique code that the
stapler verifies. If the stapler cartridge is labeled as verified, the stapler
becomes active and ready
for use. If the cartridge is rejected, however, the stapler gives a rejected
indication (e.g., a
blinking LED, an audible cue, a visual indicator). To avoid accidental or
improper reading of a
nearby staple cartridge, the antenna of the RFID reader can be constructed to
only read the RFID
when the staple cartridge is installed in the stapler or is very nearby
(optimally, at the distal end of
the device). Use of the RFID can be combined with a mechanical lockout to
ensure that only one
fire cycle is allowed per staple cartridge. RF1Ds have drawbacks because the
readers are
expensive, the antennas are required to be relatively large, and the distance
for reading is relatively
close, typically measured in centimeters.
Other wireless authentication measures Can be employed. Active RFIDs can be
used.
Similarly, infrared (IR) transmission devices can be used. However, both of
these require the
generation of power at the receiving 'end, which is a cost and size
disadvantage.
Another exemplary identification device employs encryption. With encryption
comes the
need for processing numbers and, associated with such calculations, is use of
processing chips
(e.g., a microprocessor), one of which is to be placed on the interchangeable
part, such as a staple
cartridge or a replaceable end effector shaft. Such encryption chips have
certain characteristics
that can be analyzed for optimization with the surgical instrument of the
present invention. First, a
separate power source for the interchangeable part is not desired. Not only
would such a power
source add cost, it would also add undesirable weight and take up space that
is needed for other
features or is just not available. Thus, power supply to the part should come
from the already
existing power supply within the handle. Also, supply of power should be
insured at all times.
Because the interchangeable part is relatively small, the encryption chip
should be
correspondingly small. Further, both the handle and the interchangeable part
are configured to be
disposable, therefore, both encryption processors should have a cost that
allows disposability.
Finally, connections between the encryption device on the interchangeable part
and the
corresponding encryption device on the handle should be minimized. As will be
discussed below,
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49
the encryption device according to the present invention provides all of these
desirable
characteristics and limits the undesirable ones. =
Devices for encrypted identification are commercially available. One of such
encryption
devices is produced by Dallas Semiconductor and is referred to as the DS2432
chip. The DS2432
chip not only provides encrypted identification between a reader and a
transponder, but it also has
a memory that can be used to store device-specific information, which
information and its uses
will be described in further detail below. One beneficial characteristic of
the DS2432 is that it is a
1-wire device. This means that the power and both of the input and output
signals travel on the
same line. With a 1-wire device such as the DS2432, there is only the need for
a single wire to
traverse the distance from the handle body 10 through the anvil neck 30 to the
interchangeable
staple cartridge 50 in order to make a connection between the handle and the
end effector. This
configuration satisfies the characteristic of having a minimal amount of
electrical connections and
has a correspondingly reduced cost for manufacture. It is true that the DS2432
chip requires
ground, however, the metallic anvil neck 30 is electrically conducting and is
connected to ground
of the device 1, therefore, an exemplary embodiment for the ground connection
of the DS2432
chip is made by direct electrical contact through a lead to the neck 30 or by
directly connecting the
chip's ground to the neck 30.
One exemplary encryption circuit configuration places a first encryption chip
on the
interchangeable part (e.g., the staple cartridge). Ground for the first
encryption chip is electrically
connected to a metallic portion of the interchangeable part which, in turn, is
electrically connected
to ground of the device, for example, to the neck 30. The 1-wire connection of
the DS2432 chip is
electrically connected to a contact pad that is somewhere on the
interchangeable part but is
electrically disconnected from ground. For example, if the interchangeable
part is a linear 60 mm
staple cartridge, the DS2432 can be attached to or embedded within the
electrically insulated distal
end of the cartridge distal of the last staple set. The encryption chip can be
embedded on a side of
the cartridge opposite the staple ejection face so that it is neither exposed
to the working surfaces
nor to the exposed tissue when in use. The ground lead of the DS2432 chip can
be electrically
connected to the metallic outer frame of the staple cartridge, which is
electrically connected to
ground of the stapler. The 1-wire lead is electrically connected to a first
conductive device (such
as a pad, a lead, or a boss) that is electrically insulated from the metallic
frame of the cartridge. A
single electrically conductive but insulated wire is connected at the proximal
end to the circuit
, ...õ õ.
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board or to the appropriate control electronics within the handle of the
device. This wire is
insulated from electrical contact with any other part of the stapler,
especially the grounded frame,
and travels from the handle, through the neck and up to the receiving chamber
for the
5 interchangeable pail. At the distal end, the insulated wire is exposed
and electrically connected to
a second conductive device (such as a pad, a lead, or a boss) that is shaped
to positively contact
the first conductive device on the cartridge when the cartridge is locked into
place in the end
effector. In such a configuration, the two conductive devices form a direct
electrical connection
every time that the interchangeable part (e.g., the staple cartridge) is
insetted within the end
10
effector, in one particular embodiment, contact can be made only when the
part is correctly =
inserted.
Thc DS2432 is also only a few square millimeters in area, making the chip easy
to install
on a small interchangeable part, such as a staple cartridge, while
simultaneously satisfying the
minimal size requirement. It is noted that the DS2432 chip is relatively
inexpensive. To keep all
15 commtmication with the DS2432 chip hidden from outside examination, a
DS2460 (also
manufactured by Dallas Semiconductor) can be used to perform a comparison of
an encrypted
transmission received from a 0S2432 with an expected result calculated
internally. The
characteristics of both of these chips are explained, for example, by Dallas
Semiconductors'
Application Note 3675, which is hereby incorporated by reference herein in its
entirety. The
20 DS2460 chip costs significantly more than the DS2432 chip, but is still
inexpensive enough to be
disposed along with the handle. It is noted that the number of disposable
interchangeable parts of
medical devices (such as the surgical instrument of the present invention)
typically outnumber the
handle that receives the interchangeable parts by a significant amount.
Accordingly, if the
DS2432 chip is placed in the interchangeable part and the DS2460 chip is
placed in the handle, the
25 low cost encryption characteristic is satisfied. There exists an
alternative circuit configuration
using two DS2432 chips that is explained in FIG. 2 of Application Note 3675,
which circuit
eliminates the need of the more expensive DS2460 chip by performing the
comparison with a
local microprocessor (e.g., microprocessor 2000). In such a configuration, the
cost for adding
encryption into the device 1 is reduced, however, as explained, the
configuration gives up some
30 aspects of security by making available to inspection both numbers that
are to be compared.
The process for electronically verifying the identity of an interchangeable
part on a
medical device using encryption is described with an exemplary embodiment
having one DS2432
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chip and one DS2460 chip. The exemplary control circuit for the encryption
device is shown in
FIG, 30. This exemplary embodiment is described using a linear stapler having
a handle
containing therein a circuit board with a microprocessor 2000. One free I/O
pin 2010 of the
microprocessor 2000 is connected to a first lead 2110 of the DS2460 and
another I/O pin 2020 is
connected to a second lead 2120. Each interchangeable part 2200 is provided
with a DS2432 chip
and the 1-wire lead is connected to a third I/O pin 2030 of the microprocessor
2000.
To start the process, an interchangeable part 2200 is connected to the device,
making
electrical contact with ground and with the 1-wire lead. When the
microprocessor 2000 detects
that a new part 2200 has been connected to the device 1, it runs an
authentication routine. First,
the microprocessor 2000 initiates a random number request to the DS2460 over
the first
communication pin 2010. The DS2460 has a pre-programmed secret number that is
the same as
the pre-programmed secret numbers stored in each of the DS2432 chips contained
on the
interchangeable parts 2200. Therefore, when the same random number is provided
to both the
DS2432 and the 1)52460 chips, the output result from each of the two chips
will be identical. The
DS2460 generates a random number and supplies it, via the second pin 2020, to
the
microprocessor 2000 for forwarding, via pin 2030, on to the DS2432 over the 1-
wire lead. When
the DS2432 receives the random number, it applies its SHA-1 algorithm
(developed by the
National Institute of Standards and Technology (NIST)) to cryptographically
generate a hash code
reply. This hash code reply is transmitted back over the 1-wire lead to the
microprocessor 2000
and is forwarded, via either pin 2010 or 2020 to the DS2460. During this
period of time, the
DS2460 is also calculating its own a hash code reply. First, the DS2460
internally applies the
same random number sent to the DS2432 to its own SHA-1 algorithm and stores,
internally, the
generated hash code reply. The DS2460 also stores the hash code reply
transmitted flout the
DS2432 through the microprocessor 2000. Both of the hash code replies are
compared and, if they
are identical, the interchangeable part 2200 is confirmed as authenticated. If
there is a difference
between the hash code replies, then the part 2200 is rejected and the device
is placed in a state
where the part 2200 either cannot be used or can be used, but only after
certain safeguards are met.
For example, data regarding the time, date, environment, etc. and
characteristics of the
tmauthenticated part can be stored for later or simultaneous transmission to
the manufacturer (or
its agent) to infonn the manufacturer that the user is attempting to use or
has used an unauthorized
part 2200 with the device. If there was no encryption in the messages, the
authentication messages
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52
could be intercepted and counterfeit, pirated, or unauthorized parts 2200
could be used without
having to purchase the parts 2200 from an authorized distributor. In the
exemplary encryption
embodiment described herein, the only information that is -transmitted across
lines that can be
examined is a single random number and a single hash code reply. It is
understood that it would
take hundreds of years to decrypt this SHA-1-generated reply, thus reducing
any incentive for
reverse engineering. =
Because the chips used in this example each have secure memories that can only
be
accessed after authentication occurs, they can be programmed to employ
multiple secret keys each
stored within the memory. For example, if the DS2460 has multiple keys stored
therein and the
parts 2200 each have only one key selected from this stored set of multiple
keys, the DS2460 can
act as a "master" key to the "general" single keys of the parts 2200.
By authenticating the interchangeable part of the surgical instrument of the
present
invention, many positive results are obtained. First, the instrument
manufacturer can prevent a
user from using unauthorized parts, thereby insuring use of only authorized
parts. Not only does
this guarantee that the manufacturer can receive royalties from sales of the
interchangeable part,
but it also allows the manufacture to insure that the quality of the surgical
parts remains high.
Having the encryption circuitry contain memory dramatically enhances the
benefits provided by
the present invention. For example, if a single end effector of a linear
stapler can receive 30 mm,
60 mm, and 120 mm staple cartridges, for example, each size of the cartridges
could be provided
with an individualized key and the handle can be programmed to store and use
each of these three
keys. Upon receiving a hash code reply that corresponds to one, but not the
other two internally
calculated hash code replies, the handle would know what kind of cartridge has
been inserted in
the device. Each cartridge could also contain in its memory cartridge-specific
parameters, such as
staple sled movement length, that are different among the various sized
cartridges and, therefore,
cause the handle to behave differently dependent upon the cartridge detected.
The parameters
examined can also account for revision levels in the particular part. For
example, a revision 1
cartridge could have certain parameters for use and, by detecting that
particular cartridge,
programming could cause the handle to not allow use of revision I cartridges
but allow use of
revision 2 cartridges, or vice-versa.
Having memory on the encryption chips can also allow the cartridge to keep
track of other
kinds of data. For example, the cartridge can store the identity of each
handle to which it was
-
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connected, the identity of the handle that fired the cartridge, the time, date
and other temporal data
when use and/or connection occurred, how long it took to fire the cartridge,
how many limes the
firing trigger was actuated during staple firing and many other similar
parameters. One parameter
in particular could record data when the cartridge misfires. This would allow
the manufacturer to
determine if the cartridge was faulty or if user-error occurred, for example,
the latter being
investigated to assist thenser with remedial measures or other training. By
having memory
available at the handle, other handle-relevant parameters could be stored, for
example, duration of
each procedure, speed of each staple firing, torque generated at each firing,
and/or load
experienced throughout each firing. The memory could be powered for years
merely from the
lithimn-based power cells already present in the handle. Thus, longevity of
handle data can be
ensured. The memory can be used to store all uses of a particular handle,
along with relevant
calendar data. For example, if a handle is only certified for use in a single
surgical procedure but
the handle has data indicating that staple cartridges were fired days or weeks
apart, then, when it
was finally returned to the manufacturer for recycling, the manufacturer could
detect that the user
(hospital, doctor, clinic, etc.) was improperly and, possibly, unsafely, using
the handle. Encrypted
authentication can be used with removable battery packs as well. Moreover,
sensors can be added
to any portion of the device for communicating information to be stored within
the memory of the
encryption chips. For example, temperature sensors can transmit operating room
temperature
existing when the cartridge was fired. This temperature reading can be used to
determine if later
infection was caused by improper temperature control existing during the
procedure (e.g., in
countries where air-conditioning is not available).
In the unlikely event that the stapler becomes inoperable during use, a
mechanical override
or bail-out is provided to allow manual removal of the device from the
patient. All bailout uses
can be recorded with the memory existing on these encryption chips.
Furthermore, data that could
indicate why bailout was necessary could be stored for later examination. For
quality assurance,
when bailout is detected, the handle can be programmed to indicate that a
certified letter should be
sent to the customer/user informing them of the bailout use.
As described above, the present invention is not limited to a circular
stapler, which has
been used as an exemplary embodiment above, and can be applied to any surgical
stapling head,
such as a linear stapling device, for example. Accordingly, a linear stapler
is being used in the text
=
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54
that follows for various exemplary embodiment However, use of a linear stapler
in this context
should not be considered as limited only thereto.
Described above are components that exist along the staple control axis 80 of
linear and
circular staplers and these components form the staple control assembly 200.
As set forth therein,
the required force for proper staple ejection and tissue cutting can be over
200 pounds and,
possibly, up to 250 pounds. It has been determined that minimum requirements
for carrying out
the desired stapling and cutting functions with a linear electric surgical
stapler for human tissue
(such as colon tissue, for example) are:
1) delivering approximately 54.5 kg (120 pounds) of force over a stroke of
about 60 mm
(-2.4") in approximately 3 seconds; or
2) delivering approximately 82 kg (180 pounds) of force over a stroke
of about 60 mm
(-2.4") in approximately 8 seconds.
The electric-powered, hand-held linear surgical stapling device of the present
invention can meet
these requirements because it is optimized in a novel way as set forth below,
=
To generate the force necessary to meet the above-mentioned requirements, the
maximum
power (in watts) of the mechanical assembly needs to be calculated based upon
the maximum
limits of these requirements: 82 kg over 60 mm in 3 seconds. Mathematical
conversion of these
figures generates an approximate maximum of 16 Watts of mechanical power
needed at the output
of the drive train. Conversion of the electrical power into mechanical power
is not 1:1 because the
motor has less than 100% efficiency and because the drive train also has less
than 100%
efficiency. The product of these two efficiency ratings forms the overall
efficiency. The electrical
power required to produce the 16 Watts of mechanical power is greater than the
16 Watts by an
inverse product of the overall efficiency. Once the required electrical power
can be determined,
an examination of available power supplies can be made to meet the minimum
power
requirements. Thereafter, an examination and optimization of the different
power supplies can be
made. This analysis is described in detail in the following text.
Matching or optimizing the power source and the motor involves looking into
the
individual characteristics of both. When examining the characteristics of an
electric motor, larger
motors can perform a given amount work with greater efficiency than smaller
motors. Also
motors with rare-earth magnets or with coreless construction can deliver the
same power in a
smaller size, but at higher cost Further, in general, larger motors cost less
than smaller motors if
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both are designed to deliver the same power over a given period of time.
Larger motors, however,
have an undesirable characteristic when used in surgical stapling devices
because the handle in
which they are to be placed is limited by the size of an operator's hand.
Physicians desire to use
5 devices that are smaller and lighter, not larger and heavier. Based upon
these considerations, cost,
size, and weight are factors that can be optimized fur use in the surgical
stapler handle of the
present invention.
Available motors for use within a physician's hind include motors with
relatively
inexpensive ceramic magnets and motors with relatively expensive rare earth
(i.e., neodymium)
10 magnets. However, the power increase of the latter as compared to the
former is not sufficiently
large to warrant the substantial increase in cost of the latter. Thus, ceramic
magnet motors can be
selected for use in the handle. Exemplary motors come in standard sizes
(diameter) of 273 mm or
24 mm, for example. These motors have a rated efficiency of approximately 60%
(which
decreases to 30% or below depending upon the size of the load). Such motors
operate at speeds of
15 approximately 30,000 rpm (between 20,000 and 40,000 rpm) when unloaded.
Even though such conventional motors could be used, it would be desirable to
reduce the
size even further. To that effect, the inventors have discovered that
coreless, brush-type, DC
motors produce similar power output bUt with a significant reduction in size.
For example, a 17
mm diameter coreless motor can output approximately the same Power as a
standard 24 mm
20 diameter motor. Unlike a standard motor, the coreless motor can have an
efficiency of up to 80%.
Coreless motors almost all use tare earth magnets.
With such a limited volume and mechanical power available, it is desirable to
select a
mechanical gear train having the greatest efficiency. Placing a rack and
pinion assembly as the
final drive train control stage places a high-efficiency end stage in the
drive train as compared to a
25 screw drive because, in general, the rack and pinion has an approximate
95% efficiency, and the
screw drive has a maximum of about 80% efficiency. For the linear electric
stapler, there is a 60
mm travel range for the stapling/cutting mechanism when the stapler has a 60
mm cartridge
(cartridges ranging from 30 mm to 100 mm can be used but 60 mm is used in this
example for
illustrative purposes). With this travel range, a 3-second, full travel
duration places the rack and
30 pinion extension rate at 0.8 inches per second. To accomplish this with
a reasonably sized rack
and pinion assembly; a gear train should reduce the motor output to
approximately 60 rpm. With
a motor output speed of approximately 30,000 rpm, the reduction in speed for
the drive train
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becomes approximately 500:1. To achieve this reduction with the motor, a 5-
stage drive train is
selected. It is known that such drive trains have an approximate 97%
efficiency for each stage.
Thus, combined with an approximate 95% efficiency of the rack and pinion, the
overall efficiency
of the drive train is (0.95)(0.97)5 or 82%. Combining the 60% motor efficiency
with the 82%
chive train efficiency yields an overall electrical to final mechanical
efficiency of approximately 1
1
49.2%. Knowing this overall efficiency rating, when determining the amount of
electrical power
required for operating the stapler within the desired requirements, the actual
electrical power
needed is almost twice the value that is calculated for producing the
stapling/cutting force.
' To generate the force necessary to meet the above-mentioned requirements,
the power (in
wafts) of the mechanical assembly can be calculated based upon the 82 kg over
60 mm in 3
seconds to be approximately 16 Watts. It is known that the overall mechanical
efficiency is
49.2%, so 32.5 Wafts is needed from the power supply (16 mech. watts 32.5
elec. Watts X 0.492
overall efficiency.). With this minimum requirement for electrical power, the
kind of cells
available to power the stapler can be identified, which, in this case, include
high-power Lithium
Primary cells. A known characteristic of high-power Lithium cells (e.g., CR123
or CR2 cells) is
that they produce about 5 peak watts of power per cell. Thus, at least six
cells in series will
generate the required approximate amount of 32.5 watts of electrical power,
which translates into
16 watts of mechanical power. This does not end the optimization process
because each type of
high-power Lithium cell manufactured has different characteristics for
delivering peak power and
these characteristics differ for the load that is to be applied.
Various battery characteristics exist that differentiate one battery of a
first manufacturer
from another battery of a second manufacturer. Significant battery
characteristics to compare are
those that limit the power that can be obtained from a battery, a few of which
include:
= type of electrolyte in the cell;
= electrolyte concentration and chemistry;
= how the anode and cathode are manufactured (both in chemistry and in
mechanical construction); and
= type and construction of the PTC (positive temperature coefficient of
resistance) device.
Testing of one or more of these characteristics gives valuable information in
the selection of the
most desirable battery for use in the stapling device. It has been found that
an examination of the
,=
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last characteristic -- PTC device behavior ¨ allows an optimization of the
type of battery to
perform the desired work
Most power sources are required to perform, with relative certainty and
efficiency, many
times throughout a long period of time. When designing and constructing a
power source, it is not
typical to select the power source for short-duration use combined with a low
number of uses.
However, the power source of an electric stapling device is only used for a
short duration and for a
small number of times. In each use, the motor needs to be ready for a peak
load and needs to
. perform without error. This means that, for surgical staplers, the
stapling/cutting feature will be
carried out during only one medical procedure, which has cycle counts of
between 10 and 20 uses
at most, with each use needing to address a possible peak lead of the device.
After the one
procedure, the device is taken out of commission and discarded. Therefore, the
power source for
the present invention needs to be constructed unlike any other traditional
power supply.
The device according to the present invention is constructed to have a limited
useful life of
a power cell as compared to an expected useful life of the power cell when not
used in the device.
When so configured, the device is intended to work few times after this
defined "life span." It is
known that self-contained power supplies, such as batteries, have the ability
to recover after some
kind of use. For optimization with the present invention, the device is
constructed within certain
parameters that, for a defined procedure, will perform accordingly but will be
limited or unable to
continue performance if the time of use extends past the procedure. Even
though the device might
recover and possibly be used again in a different procedure, the device is
designed to use the
power cells such that they will most likely not be able to perform at the
enhanced level much
outside the range of intended single use periods or outside the range of
aggregate use time. With
this in mind, a useful life or clinical life of the power supply or of the
device is defined, which life
can also be described as an intended use. It is understood that this
useful/clinical life does not
include periods or occurrences of use during a testing period thereof to make
sure that the device
works as intended. The life also does not include other times that the device
is activated outside
the intended procedure, i.e., when it is not activated in accordance with a
surgical procedure.
= Conventional batteries available in the market are designed to be used in
two ways: (1)
provide a significant amount of power for a short duration (such as in a high-
drain digital device
like cameras) or (2) provide a small amount of power over a long duration
(such as a computer's
clock backup). If either of these operations is not followed, then the battery
begins to heat up. If
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58
left unchecked, the battery could heat to a point where the chemicals oould
cause significant
damage, such as an explosion. As is apparent, battery explosion is to be
avoided. These extremes
are prevented in conventional batteries with the presence of the PTC device ¨
a device that is
constructed to limit conduction of the battery as the battery increases in
temperature (i.e., a
positive temperature coefficient of resistance). The PTC device protects
batteries and/or circuits
from overcurrent and overtemperature conditions. Significantly, the PTC device
protects a battery
from external short circuits while still allowing the battery to continue
functioning after the short
circuit is removed. Some batteries provide short-circuit and/or
overtemperature protection using a
one-time fuse. However, an accidental short-circuit of such a fused battery
causes the fuse to
open, rendering the battery useless. PTC-protected batteries have an advantage
over fused
batteries because they are able to automatically "reset" when the short
circuit is removed, allowing
the battery to resume its normal operation. Understanding characteristics of
the PTC device is
particularly important in the present invention because the motor will be
drawing several times
greater current than would ever be seen in a typical high-drain application.
The PTC device is provided in series with the anode and cathode and is made of
a partially
conducting layer sandwiched between two conductive layers, for example. The
device is in a low-
resistance condition at a temperature during a normal operation (depending on
circuit conditions in
which the device is used, for example, from room temperature to 40 C.). On
exposure to high
temperature due to, for example, unusually large current resulting from the
formation of a short
circuit or excessive discharge (depending on circuit conditions in which the
device is used, for
example, from 600 to 130 C), the PTC device switches into an extremely high-
resistance mode.
Simply put, when a PTC device is included in a circuit and an abnormal current
passes through the
circuit, the device enters the higher temperature condition and, thereby,
switches into the higher
resistance condition to decrease the current passing through the circuit to a
minimal level and,
thus, protect electric elements of the circuit and the battery/lea. At the
minimal level (e.g., about
20% of peak current), the battery can cool off to a "safe" level at which time
greater power can be
supplied. The partially conducting layer of the PTC device is, for example, a
composite of carbon
powder and polyolefm plastic. Further description of such devices is
unnecessary, as these
devices are described and are well known in the art.
Because PTC circuits of different manufacturers operate with different
characteristic
behaviors, the present invention takes advantage of this feature and provides
a process for
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optimizing the selection of a particular battery to match a particular motor
and a particular use.
An examination of the time when the PTC device switches to the higher
resistance condition can
be used as this indicator for optimizing a particular motor and drive train to
a battery. It is
desirable to know when the PTC device makes this switch so that, during normal
stapler use, the
PTC device does not make this change.
Exemplary batteries were loaded with various levels from approximately 3 amps
to
approximately 8 amps. At the high end, the PTC device changed to the high-
resistance state
almost immediately, making this current levCI too high for standard CR123
cells. It was
determined that, for between 4 and 6 amps, one manufacturer's cell had PTC
activation sooner
than another manufacturer's cell. The longest PTC changeover duration for the
second
manufacturer was >3 minutes for4 amps, approximately 2 minutes for 5 amps, and
almost 50
seconds for 6 amps. Each of these durations was significantly greater than the
8-second peak load
requirement. Accordingly, it was determined that the second manufacturer's
cells would be
optimal for use at peak amps as compared to the first manufacturer's cells.
Initially, it was surmised that higher amperes with lower or constant voltage
would
generate higher power out of the power cell(s). Based upon the configuration
of 6 cells in series,
the peak voltage could be 18 volts with a peak current of only 6 amps. Placing
cells in parallel, in
theory, should allow a higher peak amperage and a 3x2 configuration (two
parallel set of three
cells in series) could have a 9 volt peak with up to a 12 amp peak.
Different single cells were investigated and it was confirmed that a
relatively low voltage
(about 1.5 to 2 volts) and approximately 4 to 6 amperes produces the highest
power in Watts. Two
six-cell configurations were examined: a 6x1 series connection and a 3x2
parallel connection.
The 3x2 configuration produced the greatest peak amperes of approximately 10
amps. The 6x1
2$ configuration produced about 6 amps peak and the single cell was able to
peak at 5-6 amps before
the PTC device changed state. This information indicated the state at which
any single cell in the
series group would be activating its PTC device and, thus, limiting current
through the entire
group of cells. Thus, the tentative conclusion of yielding peak amps at lower
voltage with a 3x2
configuration was maintained.
Three different CR123 battery configurations were tested: 4x1, 6x1, and 3x2,
to see how
fast the pinion would move the tack (in inches per second ("IPS")) for the
120# and 180# loads
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and for a given typical gearing. The results of this real world dynamic
loading test are shown in
the chart of FIG. 31, for both the 120# load:
= the 4x1 battery pack was able to move the load at about 0.6 IPS at
5 approximately 2.5 amps but at approximately 8 volts;
= the 6x1 battery pack was able to move the load at about 0.9 IPS at
approximately 2.5 amps but at approximately 13 volts; and
= the 3x2 battery pack was able to move the load at about 0.4 IPS at
approximately 2.5 amps but at approximately 6 volts;
and the 180# load:
= the 4x1 battery pack was able to move the load at about 0.65 IPS at
approximately 4 amps but at approximately 7.5 volts;
= the 6x1 battery pack was able to move the load at about 0.9 IPS at
approximately 4 amps but at approximately 12 volts; and
= the 3x2 battery pac.k was able to move the load at about 0.411'S at
=
approximately 4 amps but at approximately 7 volts.
Clearly, the peak current was limited and this limit was dependent upon the
load. This experiment
revealed that the motor drew a similar current regardless of the power supply
for a given load but
that the voltage changed depending upon the battery cell configuration. With
respect to either
load, the power output was the greatest in the 6x1 configuration and not in
the 3x2 configuration,
as was expected. From this, it was determined that the total power of the cell
pack is driven by
voltage and not by current and, therefore, the parallel configuration (3x2)
was not the path to take
in optimizing the power source.
Traditionally, when designing specifications for a motor, the windings of the
motor are
matched to the anticipated voltage at which the motor will be run. This
matching takes into
account the duration of individual cycles and the desired overall life of the
product In a case of an
electric stapling device the motor will only be used for very short cycles and
for a very short life,
traditional matching methods yield results that are below optimal.
Manufacturers of the motors
give a voltage rating on a motor that corresponds to the number of tums of the
windings. The
lower the number of turns, the lower the rated voltage. Within a given size of
motor winding a
lower number of turns allows larger wire to be used, such that a lower number
of turns results in a
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lower resistance in the windings, and a higher number of turns results in a
higher resistance.
These characteristics limit the maximum current that the motor will draw,
which is what creates
most of the heat and damage when the motor is overdriven. For the present
invention, a desirable
configuration will have the lowest winding resistance to draw the most current
from the power
supply (i.e., battery pack). By running the motor at a voltage much higher
than the motor rating,
significantly greater power can be drawn from similarly sized motors. This
trait was verified with
testing of nearly identical careless motors that only varied in winding
resistance (and, hence, the
number of turns). For example, 12-volt and 6-volt rated motors were run with 6
cells (i.e., at 19.2
- 10 volts). The motors rated for 12 volts output peak power of 4 Watts with
the battery voltage only
falling slightly to 18 volts when drawing 0.7 amps. In comparison, the motors
rated for 6 volts
output 15 Watts of power with the voltage dropping to 15 volts but drawing 2
amps of current
Therefore, the lower resistance windings were selected to draw enough power
out of the batteries.
It is noted that the motor windings should be balanced to the particular
battery pack so that, in a
stall condition, the motor does not draw current from the cells sufficient to
activate the PTC,
which condition would impermissibly delay use of an electric surgical stapler
during an operation.
=
The 6x1 power cell configuration appeared to be more than sufficient to meet
the
requirements of the electric stapling device. Nonetheless, at this point, the
power cell can be .
further optimized to determine if six cells are necessary to perform the
required work. Four cells
were, then, tested and it was determined that, under the 120# load, the
motor/drive train could not
move the rack over the 60 mm span within 3 seconds. Six cells were tested and
it was determined
that, under the 120# load, the motor/drive train could move the rack over the
60 mm span in 2.1
seconds ¨ much faster than the 3-second requirement It was further determined
that, under the
180# load, the motor/drive train could move the rack over the 60 mm span in
less than 2.5 seconds
¨ much quicker than the 8-second requirement. At this point, it is desirable
to optimize the power .
source and mechanical layout to make sure that there is no "runaway"
stapling/cutting; in other
words, if the load is significantly less than the required 180# maximum, or
even the 120#
maximum, then it would not be desirable to have the rack move too fast
The gear reduction ratio and the drive system need to be optimized to keep the
motor near
peak efficiency during the firing stroke. The desired stroke of 60 mm in 3
seconds means a
minimum rack velocity of 20 mm/sec (-0.8 inches/second). To reduce the number
of variables in
the optimization process, a basic reduction of 333:1 is set in the gearbox.
This leaves the final
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reduction to be performed by the gears present between the output shaft 214 of
the gear box and
the rack 217, which gears include, for example, a bevel gear 215 and the
pinion 216 (which drives
the rack), a simplified example of which is illustrated in FIG. 32.
These variables can be combined into the number of inches of rack travel with
a single
revolution of the output shaft 214 of the 333:1 gearbox. If the gearbox output
(in rpm) never
changed, it would be a simple function to match the inches of rack travel per
output shaft
revolution ("IPR") to the output rpm to get a desired velocity as follows:
(60 rpm 4 1 revolution/second (ips); 1 rps @ 0.8 IPR 4 0.8 in/sec).
In such an idealized case, if the IPR is plotted against velocity, a straight
line would be produced.
Velocity over a fixed distance can be further reduced to Firing Time. Thus, a
plot of Firing Time
versus IPR would also be a straight line in this ideali7ed case. However,
output of the motor (in
rpm) and, therefore, of the gearbox, is not fixed because this speed varies
with the load. The
degree of load determines the amount of power the motor can put out. As the
load increases, the
rpms decrease and the efficiency changes. Based upon an examination of
efficiency with differing
loads, it has been determined that efficiency peaks at just over 60%. However,
the corresponding
voltage and amperes at this efficiency peak are not the same as at the point
of peak power. Power
continues to increase as the load increases until the efficiency is falling
faster than the power is
increasing. As the IPR increases, an increase in velocity is expected, but a
corresponding increase
in IPR lowers the mechanical advantage and, therefore, increases the load.
This increasing load,
with the corresponding decrease in efficiency at progressively higher loads,
means that a point will
exist when greater velocity out of the rack is no longer possible with greater
IPR. This behavior is
reflected as a deviation from a predicted straight line in the plot of Firing
Time (in sec) versus
IPR. Experimentation of the system of the present invention reveals that the
boundary between
unnecessary mechanical advantage and insufficient mechanical advantage occurs
at approximately
0.4 IPR.
From this IPR value, it is possible to, now, select the final gear ratio of
the bevel gear 215
to be approximately three times greater (3:1) than the sprocket of the output
shaft. This ratio
translates into an approximate IPR of 0.4.
Now that the bevel gear 215 has been optimized, the battery pack can be
reexamined to
determine if six cells could be reduced to five or even four cells, which
would save cost and
considerably decrease the volume needed for the power supply within the
handle. A constant load
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of approximately 120# was used with the optimized motor, drive train, bevel
gear, and rack and
pinion and it was discovered that use of 4 cells resulted in an almost 5
second time period for
moving the rack 60 mm. With 5 cells, the time was reduced to approximately 3.5
seconds. With a
6-cell configuration, the time was 2.5 seconds. Thus, interpolating this curve
resulted in a
minimum cell configuration of 5.5 cells. Due to the fact that cells only can
be supplied in integer
amounts, it was discovered that the 6-cell configuration was needed to meet
the requirements
provided for the electric stapling device.
From this, the minimum power source volume could be calculated as a fixed
value, unless
different sized cells could be used that provided the same electrical power
characteristics. Lithium
cells referred as CR2.s have similar electrical power characteristics as have
CR123s but are
smaller. Therefore, using a 6-cell power supply of CR2s reduced the space
requirement by more
than 17%.
As set forth in detail above, the power source (i.e., batteries), drive train,
and motor are
optimized for total efficiency to deliver the desired output force within the
required window of
time for completing the surgical procedure. The efficiency of each kind of
power source, drive
train, and motor was examined and, thereafter, the type of power source, drive
train, and motor
was selected based upon this examination to deliver the maximum power over the
desired time
period. In other words, the maximum-power condition (voltage and current) is
examined that can
exist for a given period of time without activating the PT,C (e.g.,
approximately 15 seconds). The
present invention locates the voltage-current-power value that optimizes the
way in which power
is extracted from the cells to drive the motor. Even after such optimization,
other changes can be
made to improve upon the features of the electric stapler 1.
Another kind of power supply can be used and is referred to herein as a
"hybrid" cell. In
such a configuration, a rechargeable Lithium-ion or Lithium-polymer cell is
connected to one or
more of the optimized cells mentioned above (or perhaps another primary cell
of smaller size but
of a similar or higher voltage). In such a configuration, the Li-ion cell
would power the
stapling/cutting motor because the total energy contained within one CR2 cell
is sufficient to
recharge the Li ion cell many times, however, the primary cells are limited as
to delivery. Li-ion
and Li-Polymer cells have very low internal resistance and are capable of very
high currents over
short durations. To harness this beneficial behavior, a primary cell (e.g.,
CR123, CR2, or another
cell) could take 10 to 30 seconds to charge up the secondary cell, which would
form an additional
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power source for the motor during firing. An alternative embodiment of the Li-
ion cell is the use
of a capacitor; however, capacitors are volume inefficient Even so, a super
capacitor may be put
into the motor powering system; it may be disconnected electrically therefrom
until the operator
determines that additional power is required. At such a time, the operator
would connect the
capacitor for an added "boost" of energy.
As mentioned above, if the load on the motor increases past a given point, the
efficiency
begins to decrease. In such a situation, a multi-ratio transmission can be
used to change the
delivered power over the desired time period. When the load becomes too great
such that
efficiency decreases, a multi-ratio transmission can be used to switch the
gear ration to return the
motor to the higher efficiency point, at which, for example, at least a 18011
force can be supplied.
It is noted, however, that the motor of the present invention needs to operate
in both forward and
reverse directions. In the latter operating mode, the motor must be able to
disengage the
stapling/cutting instrument from out of a "jammed" tissue clamping situation.
Thus, it would be
beneficial for the reverse gearing to generate more force than the forward
gearing.
With significantly varying loads, e.g., from low pounds up to 180 pounds,
there is the
possibility of the drive assembly being too powerful in the lower end of the
load range. Thus, the
invention can include a speed governing device. Possible governing devices
include dissipative
(active) governors and passive governors. One exemplary passive governor is a
flywheel, such as
the energy storage element 56, 456 disclosed in U.S. Patent Application No.
2005/0277955 to
Palmer et al. Another passive governor that can be used is a "fly"
paddlewheel. Such an assembly
uses wind resistance to govern speed because it absorbs more force as it spins
faster and, therefore,
provides a speed governing characteristic when the motor is moving too fast.
Another kind of
governor can be a compression spring that the motor compresses slowly to a
compressed state.
When actuation is desired, the compressed spring is released, allowing all of
the energy to be
transferred to the drive in a relatively short amount of time. A further
exemplary governor
embodiment can include a multi-stage switch having stages that arc connected
respectively to
various sub-sets of the battery cells. When low force is desired, a first
switch or first part of a
switch can be activated to place only a few of the cells in the power supply
circuit As more
power is desired, the user (or an automated computing device) can place
successive additional
cells into the power supply circuit. For example, in a 6-cell configuration,
the first 4 cells can be
connected to the power supply circuit with a first position of a switch, the
fifth cell can be
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connected with a second position of the switch, and the sixth cell can be
connected with a third
position of the switch.
Electric motors and the associated gear box produce a certain amount of noise
when used.
5 The stapler of the present invention isolates the motor and/or the motor
drive train from the handle
to decrease both the acoustic and vibration characteristics and, thereby, the
overall noise produced
during operation, ht a first embodiment, a dampening material is disposed
between the handle
body and both of motor and the drive train. The material can be foam, such as
latex, polyester,
plant-based, polyether, polyetherimide, polyimide, polyolefin, polypropylene,
phenolic,
10 polyisocyanates, polyurethane, silicone, vinyl, ethylene copolymer,
expanded polyethylene,
fluoropolymer, or styrofoam. The material can be an elastomer, such as
silicone, polyurethane,
chlomprene, butyl, polybutadiene, neoprene, natural rubber, or isoprene. The
foam can be closed
cellular, open cellular, flexible, reticular, or syntactic, for example. The
material can be placed at
given positions between the handle and motor/gear box or can entirely fill the
chamber
15 surrounding the motor/gear box. In a second embodiment, the motor and
drive train are isolated
within a nested box configuration, sometimes icfcaal to as a "Chinese Box" or
"Russian nesting
doll." In such a configuration, the dampening material is placed around the
motor/gear box and
the two are placed within a first box with the gear box shaft protruding
therefrom. Then, the first
box is mounted within the "second box"¨ the handle body and the dampening
material is place
20 between the first box and the handle interior.
The electric stapler of the present invention can be used in surgical
applications Most
stapling devices are one-time use. They can be disposed after one medical
procedure because the
cost is relatively low. The electric surgical stapler, however, has a greater
cost and it may be
desirable to use at least the handle for more than one medical procedure.
Accordingly,
25 sterilization of the handle components after use becomes an issue.
Sterilization before use is also
significant. Because the electric stapler includes electronic components that
typically do not go
through standard sterilization processes (i.e., steam or gamma radiation), the
stapler needs to be
sterilized by other, possibly more expensive, means such as ethylene-oxide
gas. It would be
desirable, however, to make the stapler available to gamma radiation
sterilization to reduce the
30 cost associated with gas sterilization. It is known that electronics are
usable in space, which is an
environment where such electronics are exposed to gamma radiation. In such
applications,
however, the electronics need to work while being exposed. In contrast, the
electric stapler does
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not need to work while being exposed to the gamma sterilization radiation.
When semiconductors
are employed, even if the power to the electronics is turned off, gamma
radiation will adversely
affect the stored memory. These components only need to withstand such
radiation and, only after
exposure ceases, need to be ready for use. Knowing this, there are various
measures that can be
taken to gamma-harden the electronic components within the handle. First,
instead of use
MOSFET memory, for example, fusable link memories can be used. For such
memories, once the
fuses are programmed (i.e., burnt), the memory becomes permanent and resistant
to the gamma
sterilization. Second, the memory can be mask-programmed. If the memory is
hard programmed
using masks, gamma radiation at the level for medical sterilization will not
adversely affect the
programming. Third, the sterilization can be performed while the volatile
memory is empty and,
after sterilization, the memory can be programmed through various measures,
for example, a
wireless link including infrared, radio, ultrasound, or Bluetooth
communication can be used.
Alternatively, or additionally, external electrodes can be contacted in a
clean envirorunent and
these conductors can program the memory. Finally, a radiopaque shield (made
from molybdenum
or tungsten, for example) can be provided around the gamma radiation sensitive
components to
prevent exposure of these components to the potentially damaging radiation.
As set forth herein, characteristics of the battery, drive train, and motor
are examined and
optimized for an electric stapling application. The particular design (i.e.,
chemistry and PTC) of a
battery will determine the amount of current that can be supplied and/or the
amount of power that
can be generated over a period of time. It has been determined that standard
alkaline cells do not
have the ability to generate the high power needed over the short period of
time to 'effect actuation
of the electric stapling device. It was also determined that some lithium-
manganese dioxide cells
also were unable to meet the needs for actuating the stapling device.
Therefore, characteristics of
certain lithium-manganese dioxide cell configurations were examined, such as
the electrolyte and
the positive temperature coefficient device.
It is understood that conventional lithium-manganese dioxide cells (e.g.,
CR123 and CR2)
are designed for loads over a long period of time. For example, SUREFIRE
markets flashlights
and such cells and states that the cells will last for from 20 minutes to a
few hours (3 to 6) at the
maximum lumen output of the flashlight. Load upon the calls(s) during this
period of time is not
close to the power capacity of the battery(ies) and, therefore, the critical
current rate of the
battery(ies) is not reached and there is no danger of overheating or
explosion. If such use is not
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continuous, the batteries can last through many cycles (i.e., hundreds) at
this same full power
output
Simply put, such batteries are not designed for loads over a period of 10
seconds or less,
for example, five seconds, and are also not designed for a small number of
uses, for example, ten
to fifteen. What the present invention does is to configure the power supply,
drive train, and
motor to optimize the power supply (i.e., battery) for a small number of uses
with each use
occurring over a period of less than ten seconds and at a load that is
significantly higher than rated.
All of the primary lithium cells that were examined possess a critical current
rate defined
by the respective PTC device and/or the chemistry and internal construction.
If used above the
critical current rate for a period of time, the cells can overheat and,
possibly, explode. When
exposed to a very high power demand (close to the PTC threshold) with a low
number of Cycles,
the voltage and amperage profiles do not behave the same as in prior art
standard uses. It has been
found that some cells have PTC devices that prevent generation of power
required by the stapler of
the present invention, but that other cells are able to generate the desired
power (can supply the
current an voltage) for powering the electric stapling device. This means that
the critical current
rate is different depending upon the particular chemistry, construction,
and/or PTC of the cell.
The present invention configures the power supply to operate in a range above
the critical
current rate, referred to herein as the "Super-Critical Curront Rate." It is
noted within the
definition of Super-Critical Current Rate also is an averaging of a modulated
current supplied by
the power supply that is above the critical current rate. Because the cells
cannot last long while
supplying power at the Super-Critical Current Rate, the time period of their
use is shortened. This
shortened time period where the cells are able to operate at the Super-
Critical Current Rate is
referred to herein as the "Super-Critical Pulse Discharge Period," whereas the
entire time when the
power supply is activated is referred to as a "Pulse Discharge Period." In
other words, the Super-
Critical Pulse Discharge Period is a time that is less than or equal to the
Pulse Discharge Period,
during which time the current rate is greater than the critical current rate
of the cells. The Super-
Critical Pulse Discharge Period for the present invention is less than about
16 seconds, in other
words, in a range of about one-half to fifteen seconds, for example, between
two and four seconds
and, more particularly, at about three seconds. During the life of the
stapling device, the power
supply may be subjected to the Super-Critical Current Rate over the Pulse
Discharge Period for at
least one time and less than twenty times within the time of a clinical
procedure, for example,
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between approximately five and fifteen times, in particular, between ten and
fifteen times within a
period of five minutes. Therefore, in comparison to the hours of use for
standard applications of
the power supply, the present invention will have an aggregate use, referred
to as the Aggregate
Pulse Time, of, at most, approximately 200 to 300 seconds, in particular,
approximately 225
seconds. It is noted that, during an activation, the device may not be
required to exceed or to
always exceed the Super-Critical Current Rate in a given procedure because the
load presented to
the instrument is dependent upon the specific clinical application (i.e., some
tissue is denser than
others and increased tissue density will increase load presented to device).
However, the stapler is
designed to be able to exceed the Super-Critical Current Rate for a number of
times during the
intended use of the surgical procedure. Acting in this Super-Critical Pulse
Discharge Period, the
device can operate a sufficient amount of times to complete the desired
surgical procedure, but not
many more because the power supply is asked to perform at an increased
current.
When performing in the increased range, the force generated by the device,
e.g., the
electric stapler 1, is significantly greater than existed in a hand-powered
stapler. In fact, the force
is so much greater that it could damage the stapler itself. In one cXemplary
use, the motor and
drive assemblies can be operated to the detriment of the knife blade lock-out
feature -- the safety
that prevents the knife blade 1060 from advancing when there is no staple
cartridge or a previously
fired staple cartridge in the staple cartridge holder 1030. This feature is
illustrated in FIG. 33. As
discussed, the knife blade 1060 should be allowed to move distally only when
the staple sled 102
is present at the firing-ready position, i.e., when the sled 102 is in the
position illustrated in FIG.
33. If the sled 102 is not present in this position, this can mean one of two
things, either there is
no staple cartridge in the holder 1030 or the sled 102 has already been moved
distally in other
words, a partial or full firing has already occurred with the loaded staple
cartridge. Thus, the blade
1060 should not be allowed to move, or should be restricted in its movement
Accordingly, to =
insure that the sled 102 can prop up the blade 1060 when in a firing state,
the sled 102 is provided
with a lock-out contact surface 104 and the blade 1060 is provided with a
correspondingly shaped =
contact nose 1069. It is noted at this point that, the lower guide wings 1065
do not rest against a
floor 1034 in the cartridge holder 1030 until the blade 1060 has moved
distally past an edge 1035.
With such a configuration, if the sled 102 is not present at the distal end of
the blade 1060 to prop
up the nose 1069, then the lower guide wings 1065 will follow the depression
1037 just proximal
of the edge 1035 and, instead of advancing on the floor 1034, will hit the
edge 1035 and prevent
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further forward movement of the blade 1060. To assist with such contact when
the sled 102 is not
present (referred to as a "lock out"), the staple cartridge 1030 has a plate
spring 1090 (attached
thereto by at least one rivet 1036) for biasing the blade 1060. With the plate
spring 1090 flexed
upward and pressing downward against the flange 1067 (at least until the
flange 1067 is distal of
the distal end of the plate spring 1090), a downwardly directed force is
imparted against the blade
_ 1060 to press the wings 1065 down into the depression 1037. Thus, as the
blade 1060 advances
distally without the sled 102 being present, the wings 1065 follow the lower
curve of the
depression 1037 and are stopped from further distal movement when the distal
edge of the wings
1065 hit the edge 1035.
This safety feature operates as described so long as the force transmitted by
the knife
blades 1062 to the blade 1060 is not great enough to tear off the lower guide
wings1065 from the
blade 1060. With the forces able to be generated by the power supply, motor
and drive train of the
present invention, the blade 1060 can be pushed distally so strongly that the
wings 1065 are torn
away. If this occurs, there is no way to prevent distal movement of the blade
1060 or the sled 102.
Accordingly, the present invention provides a way to lower the forces able to
be imparted upon the
wings 1065 prior to their passage past the edge 1035. In other words, the
upper limit of force able
to be applied to the Made 1060 is reduced in the first part of blade travel
(past the edge 1035) and
increases after the wings 1065 have cleared the edge 1035 and rest on the
floor 1034. More
specifically, a first exemplary embodiment of this two-part force generation
limiter takes the form
of a circuit in which only one or a few of the cells in the power supply are
connected to the motor
during the first part of the stapling/cutting stroke and, in the second pelt
of the stapling/cutting
stroke, most or all of the cells in the power supply are connected to the
motor. A first exemplary
form of such a circuit is illustrated in FIG. 34. In this first embodiment,
when the switch 1100 is
in the "A" position, the motor (e.g., stapling motor 210) is only powered with
one power cell 602
(of a possible four in this exemplary embodiment). However, when the switch
1100 is in the "B"
position, the motor is powered with all four of the cells 602 of the power
supply 600, thereby
increasing the amount of force that can be supplied to the blade 1060. Control
of the switch 1100
between the A and B positions can occur by positioning a second switch
somewhere along the
blade control assembly or along the sled 102, the second switch sending a
signal to a controller
after the wings 1065 have passed the edge 1035. It is noted that this first
embodiment of the
control circuit is only exemplary and any similarly performing assembly can
provide the lock-out
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protection for the device, see, for example, the second exemplary embodiment
illustrated in FIG.
36.
A first exemplary form of a forward and reverse motor control circuit is
illustrated in FIG.
5 35. This first exemplary embodiment uses a double-throw, double pole
switch 1200. The switch
1200 is normally spring-biased to a center position in which both poles are
off. The motor M
illustrated can, for example, represent the stapling motor 210 of the present
invention. As can be
seen, the power-on switoh 1210 must be closed to turn on the device. Of
course, this switch is
optional. When a forward movement of the motor M is desired, the switch 1200
is placed in the
10 right position as viewed in FIG. 35, in which power is supplied to the
motor to run the motor in a
first direction, defined as the forward direction here because the "+" of the
battery is connected to
the "+" of the motor M. In this forward switching position, the motor M can
power the blade 1060
in a distal direction. Placement of an appropriate sensor or switch to
indicate the forward-most
desired position of the blade 1060 or the sled 102 can be used to control a
forward travel limit
15 switch 1220 that interrupts power supply to the motor M and prevents
further forward travel, at
least as long as the switch 1220 remains open. Circuitry can be programmed to
never allow this
switch 1220 to close and complete the circuit or to only allow resetting of
the switch 1220 when a
new staple cartridge, for example, is loaded.
When a reverse movement of the motor M is desired, the switch 1200 is placed
in the left
20 position as viewed in FIG. 35, in which power is supplied to the motor
to run the motor in a
second direction, defined as the reverse direction here because the "-" of the
battery is connected
to the "+" of the motor M. In this reverse switching position, the motor M can
power the blade
1060 in a proximal direction. Placement of an appropriate sensor or switch to
indicate the
rearward-most desired position of the blade 1060 or the sled 102 can be used
to control a rearward
25 travel limit switch 1230 that interrupts power supply to the motor M and
prevents further rearward
travel, at least as long as the switch 1230 remains open. It is noted that
other switches (indicated
with dotted arrows) can be provided in the circuit to selectively prevent
movement in either
direction independent of the limit switches 1220, 1230.
It is noted that the motor can power the gear train with a significant amount
of force, which
30 translates into a high rotational inertia. As such, when any switch
mentioned with respect to
FIGS. 34 and 35 is used to turn off the motor, the gears may not just stop.
Instead, the rotational
inertia continues to propel, for example, the rack 217 in the direction it was
traveling when power
CA 02725690 2010-12-10
WO 2007/137304 PCT/US2007/070085
71
to the motor was terminated. Such movement can be disadvantageous for many
reasons. By
configuring the power supply and motor appropriately, a circuit can be formed
to substantially
eliminate such post-termination movement, thereby giving the user more control
over actuation.
FIG. 36 illustrates an exemplary embodiment where the motor (for example,
stapling
motor 210) is arrested from further rotation when forward or reverse control
is terminated. FIG.
36 also illustrates alternative embodiments of the forward/reverse control and
of the multi-stage
power supply. The circuit of FIG. 36 has a motor arrest sub-circuit utilizing
a short-circuit
property of an electrical motor. More specifically, the electrical motor M is
placed into a short- =
I 0 circuit so that an electrically generated magnetic field is created in
opposition to the permanent
magnetic field, thus slowing the still-spinning motor at a rate that
substantially prevents inertia-
induced over-stroke. To explain how the circuit of FIG. 36 can brake the motor
M, an explanation
of the forward/reverse switch 1300 is provided. As can be seen, the
forward/reverse switch 1300
has three positions, just like the switch 1200 of FIG. 35. When placed in the
right position, the
motor M is actuated in a forward rotation direction. When placed in the left
position, the motor M
is actuated in a rearward rotation direction. When the switch 1300 is not
actuated ¨ as shown in
FIG. 36¨ the motor M is short circuited. This short circuit is
diagrammatically illustrated by the
upper portion of the switch 1300. It is noted that the switching processes in
a braking switch is
desired to take place in a time-delayed manner, which is also referred to as a
break-before-make
switching configuration. When switching over from operating the motor M to
braking the motor
M, the double-pole, double throw portion of the forward/reverse switch 1300 is
opened before the
motor short circuit is effected. Conversely, when switching over from braking
the motor M to
operating the motor M, the short circuit is opened before the switch 1300 can
cause motor
actuation. Therefore, in operation, when the user releases the 3-way switch
1300 from either the
forward or reverse positions, the motor M is short-circuited and brakes
quickly.
Other features of the circuit in FIG. 36 have been explained with regard to
FIG. 35. For
example, an on/off switch 1210 is provided. Also present is the power lock-out
switch 1100 that
only powers the motor with one power cell 602' in a given portion of the
actuation (which can
occur at the beginning or at any other desired part of the stroke) and powers
the motor M with all
of the power cells 602 (here, for example, six power cells) in another portion
of the actuation.
A new feature of the reverse and forward limit switches 1320, 1330.prevents
any further
forward movement of the motor M after the forward limit switch 1320 is
actuated. When this
;
CA 02725690 2012-11-28
72
limit is reached, the forward limit switch 1320 is actuated and the switch
moves to the second
position. In this state, no power can get to the motor for forward movement
but power can be
delivered to the motor for reverse movement. The forward limit switch can be
programmed to
toggle or be a one-time use for a given staple cartridge. More specifically,
the switch 1320 will
remain in the second position until a reset occurs by replacing the staple
cartridge with a new one.
Thus, until the replacement occurs, the motor M can only be powered in the
reverse direction. If
the switch is merely a toggle, then power can be restored for additional
further movement only
when the movement has retreated the part away from actuating the switch 1320.
The reverse limit switch 1330 can be configured similarly. When the reverse
limit is
reached, the switch 1330 moves to the second position and stays there until a
reset occurs. It is
noted that, in this position, the motor M is in a short-circuit, which
prevents motor movement in
either direction. With such a configuration, the operation of the stapler can
be limited to a single
stroke up to the forward limit and a single retreat up to the rear limit. When
both have occurred,
the motor M is disabled until the two switches 1320 are reset.
The foregoing description and accompanying drawings illustrate the principles,
preferred
embodiments and modes of operation of the invention. More specifically, the
optimized power
supply, motor, and drive train according to the present invention has been
described with respect
to a surgical stapler. However, the invention should not be construed as being
limited to the
particular embodiments discussed above. Additional variations of the
embodiments discussed
above will be appreciated by those skilled in the art as well as for
applications, unrelated to
surgical devices, that require an advanced power or current output for short
and limited durations
with a power cell having a limited power or current output. As is shown and
described, when
optimized according to the present invention, a limited power supply can
produce lifting, pushing,
pulling, dragging, retaining, and other kinds of forces sufficient to move a
substantial amount of
weight, for example, over 82 kg.
=
