Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRICAL SURGICAL INSTRUMENT
This application is a divisional of Canadian patent application Serial No.
2,725,181, which in turn is a divisional of Canadian patent application Serial
No.
2,629,276 filed internationally on May 31, 2007 and entered nationally on May
8, 2008.
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
PROXIMATE4-1) 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, for
example, in
U.S. Patent No. 5,104,025 to Main et al., and assigned to Ethicon. Main et al.
is hereby
incorporated herein by reference in its entirety. 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
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
An offset-axis configuration for the two anvil and staple firing sub-
assemblies
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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 retracted back into the handle and the handle is
inserted trans-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 actuate the at least one actuation
assembly,
the power supply operates the at least one battery cell at a super-critical
current rate.
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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.
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.
Although the invention is illustrated and described herein as embodied in an
electrical surgical instrument with optimized power supply and drive, it is,
nevertheless,
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not intended to be limited to the details shown because various modifications
and
structural changes may be made therein without departing from 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
5 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 accompanying 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;
FIG. 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. 7 is an enlarged, fragmentary, exploded, perspective view of the staple
firing
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. 1;
FIG. 9 is a fragmentary, enlarged, horizontally cross-sectional view from
below a
proximal portion of the anvil control assembly FIG. 8;
FIG. 10 is a fragmentary, enlarged, horizontally cross-sectional view from
below
an intermediate portion of the anvil control assembly of FIG. 8;
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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 FIG. 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
side 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. 1 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;
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;
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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;
FIG. 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 are 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 of the medical device according to the 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.
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.
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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
wireframe 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 1. 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 (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.
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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 1 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 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-pending U.S. Patent Provisional Application
Serial No.
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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
5 house and/or fix various part of the anvil control assembly 100 thereto.
The anvil control
frame 110 has a proximal mount 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
10 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 ease 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 142 to have these parts
spin efficiently
and substantially without friction 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 further decrease the
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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 has a distal plate 232 that is shown, for example in FIG. 6. The
distal plate 232
is removable from the coupling mount 230 so that a rotating screw 250 can be
held
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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
circumference 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 intermediate
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
bushing 260,
which is formed of a material that is softer than the intermediate coupling
mount 230. The
proximal radius screw bushing 260 only keeps the screw 250 axially aligned and
does not
absorb or transmit any of the longitudinal thrust. The second increasing step
in diameter is
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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
effectively deploy the staples. Two particular exemplary materials provide the
desired
characteristics and are referred to in the art as DELRIN AF Blend Acetal (a
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thermoplastic material combining TEFLON fibers uniformly dispersed in DELRIN
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 the trocar tip 410 housed within the staple cartridge
and which is
CA 02847464 2014-03-26
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 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
5 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 143 is positioned within the central bore 144 of the distal
nut half 142.
10 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 different
longitudinal speeds.
15 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 microcontroller 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 pre-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 greater
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
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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.
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-
fully-extended
switch 610 when the rod 180 (and, thereby, the anvil 60) is in the fully
extended position.
A 1-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 (see
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 programming 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
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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.
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 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.
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19
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 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 devices), 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 16F684.
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
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software that are uploaded to the processor adjust the control and user
interface without
changing the wiring or mechanical layout of the device.
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
5 removed from the device. The removal enables battery contact, thus
powering on the
device.
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,
10 referred 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 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) are used to provide feedback to the user. In
the case
15 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 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.
20 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 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
CA 02847464 2014-03-26
21
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 data. Response from
the stapler 1 to
such a query can be in the form of blinking LEDs, or, in the case 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 1 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 staple 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
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22
is returned to home position, and staple firing button remains active
ready for a re-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 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 trocar 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 unpackaged and ready to be used for surgery, the
user
turns 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/trocar 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 trocar 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 trocar 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,
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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 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
closes 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.
CA 02847464 2014-03-26
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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 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 press 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
CA 02847464 2014-03-26
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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
5 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.
After a completed staple firing, the anvil 60 remains in the closed position
and only
10 the extend switch 20 remains active (all other switches are
deactivated). Once the anvil 60
is extended to at least the home position, both the extend and retract
switches 20, 21 are
made active 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
15 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 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
20 out the methods according to the invention as described herein. The text
that follows is
only submitted as exemplary and those of skill in the art can appreciate that
programming
the methods according to the invention can take many different forms to
achieve the same
functionality.
25 'Circular Stapler Program using the rev 3c board (cb280 chipset) V8.03
(CS-3c-
080306.CUL)
'8-3-06
'Modified program to abort with only fire button, added pbcount variable
'Added PWM ramping
'7-28-06
'final tweaks - stan is now an integer etc.
'7-17-06 This version written for the 3c board.
'7-14 DEBUGGING VERSION
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'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 1
cm switch.
This version uses
'a limit switch at either end of the extend/retract stage.
'V6.20 Final Version of Gray Logic program as used in prototype 0, serial
number 100
'V6.05
'modified 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
'V6.02
'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 Cubloc
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 on the actual
device.
'limited the values of the EEPROM data to 255 max
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'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 of jog routine button presses
'added the recording of datadump requests
'V5.26
'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
'V5.24 works well, no known bugs (circular-stapler-5-24.cul)
'1(MS Medical LLC (c) 2006
'MAP
'Pl0 Extend Button
'Pll Retract Button
'P12 Fire Button
'P13 Extend Limit
'P14 Retract Limit
'P15 Fire Forward Limit
'P16 Fire Back Limit
'P17 1 cm Limit Switch
'P18 Staple Range Limit Switch
'P19 Force Switch
'P20 Extend Button LED
'P21 Retract Button LED
'P22 Fire Button LED
'P23 Force LED (blue)
'P24 Not USED
'P25 Not USED
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'P26 Not USED
'P27 Not USED
'P28 Not USED
'P29 Staple Range LED (green)
Const Device=cb280 'Comfile Tech. Cubloc CB280 chipset
Dim ver As String*7
ver="3C-8.03" 'set software version here
Dim extendbutton As Byte
Dim retractbutton As Byte
Dim firebutton As Byte
Dim firstout As Byte
Dim firstback As Byte
Dim cmstatus As Byte 'lcm 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 extlimit As Byte
Dim retlimit As Byte
Dim speed As Integer
Dim dracula As Byte
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'initalize outputs
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=0
completefire=0
arm=0
bail=0
cycnumfires=0
cycabortfires=0
cycers=0
cycjogs=0
extendonly=0
'CHANGE PWM VALUES HERE
fast=60000 'highspeed pwm value
slovv=60000 'Iowspeed pwm value
speed=0
Output 5 'turns on pwm output for PINCH
Output 6 'turns on pwm output for FIRE
'read totals from eeprom
powerons=Eeread(2,1)
Incr 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 number to eeprom
ds=powerons*5
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
For x=1 To 50
10 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 Keyin(11,20)=0 Or Keyin(12,20)=0 Then 'either e/r
button or the fire button pressed
15 jog
Exit For
End If
Delay 20
Next
20 ' -------------------------------------
'HOMING SEQUENCES
cmstatus¨Keyin(17,20) 'read the status of the lcm limit switch
If cmstatus=0 Then
homeretract
Elseif cmstatus=1 Then
homeextend
End If
'Return fire motor to back position
homefire 'this returns the fire motor to the full retracted condition (P6
limit switch)
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****************
'Main Loop
!************************************************************************
****************
Do
'Debug "Main Loop",Cr
'Delay 1000
cmstatus¨Keyin(17,20) 'read the 1 cm switch
istaplerangestatus¨Keyin(5,20) 'read the staplerange limit switch
extendbutton¨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 'turn on retract limit
Elseif cmstatus=1 Then
Out 20,1
Out 21,0
End If
'check firebutton led status
If firstout=1 And firstback=1 And arm=1 And completefire<>1 And cmstatus<>0
Then
Out 22,1 'turn on fire button led
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Else
Out 22,0 'turn off fire led
End If
'check for extend retract button press
If extendbutton=0 And cmstatus=0 Then
extend
Elseif cmstatus=1 And extendbutton=0 Then
extend
End If
If retractbutton=0 And cmstatus=0 Then 'And extendonly=0
retract
End If
'check for firebutton press
If firebutton=0 And firstout=1 And firstback=1 And arm=1 And completefire<>1
And cmstatus<>0 Then initialfire
Loop 'keep looping til powerdown
End 'End of program
,************************************************************************
SUBROUTINES
'HOME: retract to cm switch¨not pressed
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Sub homeretract() 'retract until 1 cm switch is open
'Debug "Homeretract",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 'er 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¨pressed
Sub homeextend() 'extend until 1 cm switch is closed
'Debug "Homextend",Cr
'Delay 1000
Pwm 0,slow,60000
If Keyin(17,20)=1 Then
Do Until Keyin(17,20)=0 'now the 1 cm switch is pressed
Out 30,1 'ER motor forward DDD
Loop
End If
Out 30,0 'DDD
Pwmoff 0
Delay 300
homeretract 'once the switch is made, call homeretract
End Sub
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'Fire motor homing routine
, --------------------------------------------------
Sub homefire()
'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 jog()
Out 20,1
Out 21,1
Do
Delay 25
If Keyin(10,20)=0 And Keyin(11,20)=0 Then Exit Do 'if both buttons pressed,
exit
jog routine and start homing routine after 1 second delay
If Keyin(10,20)=0 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
Loop
Out 30,0 'extend motor off forward DDD
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Pwmoff 0
Incr cycjogs
If cycjogs>=255 Then cycjogs=255
Eewrite ds+3,cycjogs,1
5 End If
If Keyin(11,20)=0 And Keyin(10,20)<>0 And Keyin(12,20)<>0 Then
Pwm 0,slow,60000
Do Until Keyin(11,20)<>0 Or Keyin(14,20)=0
10 Out 31,1 'extend motor reverse
Loop
Out 31,0 'extend motor off reverse
Pwmoff 0
Incr cycjogs
15 If cycjogs>=255 Then cycjogs=255
Eewrite ds+3,cycjogs,1
End If
If Keyin(12,20)=0 And Keyin(10,20)=0 Then jog the fire motor forward
20 Pwm 1,slow,60000
Do Until Keyin(10,20)<>0 Or Keyin(12,20)<>0 Or Keyin(15,20)=0
Out 32,1 'fire motor forward
Loop
Out 32,0 'fire motor off forward
25 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 jog the fire motor reverse
Pwm 1,slow,60000
Do Until Keyin(11,20)<>0 Or Keyin(12,20)<>0 Or Keyin(16,20)=0
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Out 33,1 'fire motor reverse
Loop
Out 33,0 'fire motor off reverse
Pwmoff 1
Incr cycjogs
If cycjogs>=255 Then cycjogs=255
Eewrite ds+3,cycjogs,1
End If
Loop
Do Until Keyin(10,20)=1 And Keyin(11,20)=1 'let off both buttons before
exiting jog
routine
Delay 10
Loop
Out 20,0 'turn on e/r button leds
Out 21,0
Delay 1000
End Sub
'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
Pwm 0,fast,60000
Do Until Keyin(10,20)=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
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If firstout=0 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
End If
Out 30,0 'DDD
Pwmoff 0
Incr cycers
If cycers>=255 Then cycers=255
Eewrite ds+2,cycers,1
If Keyin(13,20)=0 Then
firstout=1 'set the firstout flag to enable fire button
Out 20,0 'turn off extend led
End If
End Sub
'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
Pwm 0,fast,60000
Do Until Keyin(11,20)=1 Or Keyin(17,20)=1 'retract until either the lcm switch
goes open
or the extend button is released
Out 31,1 'ER motor reverse
Loop
Out 31,0
Pwmoff 0
Incr cycers
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If cycers>=255 Then cycers=255
Eewrite ds+2,cycers,1
If Keyin(17,20)=1 Then
firstback=1
Out 21,0 'turn retract led off
End If
If firstout=1 And firstback-----1 Then arm=1 'set the arm flag to arm the fire
button
End Sub
'DATADUMP Routine
Sub datadump()
Dim chef As Byte
Dim tf As Byte 'total fires
Dim ta As Byte 'total aborts
Dim ers As Integer
Dim tj As Byte
Dim tdd As Byte
Dim stan As Integer
Dim kyle As Byte
Dim token As Byte
Dim ike As Byte
Dim kenny As Byte
Dim sn As Byte
tf=0
ta=0
ers=0
tj=0
tdd=0
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Eewrite ds+4,1,1 'write 1 to the ds+4 eeprom register denoting that datadump
was
accessed
Delay 1000
sn=Eeread(0,1)
Debug "Circular Stapler Stored Data",Cr
Debug "Version ",ver,Cr
Debug "KMS Medical LLC",Cr
Debug" ------------------------- ",Cr
Debug Cr
Debug "Serial Number: ",Dec sn,Cr
powerons=Eeread(2,1)
If powerons>=255 Then powerons=255
Debug "Total Cycles: ",Dec powerons,Cr
Debug Cr
Debug" ---------------------- ",Cr
Debug Cr
For stan=5 To (powerons*5) Step 5
Debug "Cycle ",Dec (stan/5),Cr
Debug" ------------------------------- ",Cr
chef=-Eeread(stan,l)
tf=chef+tf
Debug "Completed Fires: ",Dec chef,Cr
kyle=Eeread(stan+1,1)
ta=kyle+ta
Debug "Aborted Fires: ",Dec kyle,Cr
token=Eeread(stan+2,1)
ers=token+ers
Debug "E/Rs: ",Dec token,Cr
ike=Eeread(stan+3,1)
tj=ike+tj
Debug "Jogs: ",Dec ike,Cr
kenny=Eeread(stan+4,1)
tdd=kenny+tdd
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Debug "Datadumps: ",Dec kenny,Cr
Debug Cr
Next 'stan
5 Debug" ----------------------- ",Cr
Debug "Cycle Totals",Cr
Debug Cr
Debug "Completed Fires: ",Dec tf,Cr
Debug "Aborted Fires: ",Dec ta,Cr
10 Debug "E/R Presses: ",Dec ers,Cr
Debug "Jog Presses: ",Dec tj,Cr
Debug "Datadumps: ",Dec tdd,Cr
Debug Cr
15 Delay 1000
For x=1 To tf 'blink the number of completed firing cycles
Out 22,1
Delay 500
Out 22,0
20 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
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Dim z As Integer
Dim q As Integer
Dim timmy 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
Out 21,0 'retract button
bail=0
t=15 'total blink time
p=3 'number of blink periods
Pwm 0,fast,60000
'start blink and adjust pinch motor to force
f=(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 timmy=0 Then timmy=1
If Keyin(12,20)=0 And fbcount=1 Then
bail=1 'set abortfire flag
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Exit For
End If
If Keyin(12,20)=1 Then fbcount=1
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(12,20)=1 Then fbcount=1
Loop
If bail=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
End If
If Keyin(12,20)=1 Then fbcount=1
If Keyin(19,20)=1 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
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If Keyin(12,20)=1 Then fbcount=1
Loop
Out 31,0
Out 23,1
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
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 fbcount=1
If Keyin(19,20)=1 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 0
If bail=1 Then
abortfire
Else
'staplerangecheck
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finalfire
End If
End Sub
' -------------------------------------------
'Staple Range Check Routine
Sub staplerangecheck()
srstatus¨Keyin(29,20) 'read the staplerange limit switch
If srstatus=0 Then
finalfire
Else
abortfire
End If
End Sub
'Final Fire Routine
' ---------------------------------------------
Sub finalfire()
Out 23,0 'turn force led off
Out 20,0 'turn extend led off
Out 21,0 'turn retract led off
Out 22,1 'Turn on fire led to signify final fire abort ready
Pwmoff 1
'Pwm 1,fast,60000
'Out 32,1 'fire motor forward DDD
completefire=1
Do Until Keyin(15,20)=0 'fire forward until forward limit is met
If speed>=60000 Then speed=60000
If speed<60000 Then
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speed=speed+10000
End If
Pwm 1,speed,60000
Out 32,1
5 Delay 50
If Keyin(12,20)=0 Then 'Or Keyin(10,20)=0 Or Keyin(11,20)=0
bail=1
Exit Do
End If
10 Loop
Out 32,0 'fire motor fwd off DDD
speed=0
15 Delay 250
Do Until Keyin(16,20)=0 'retract fire motor
If speed>=60000 Then speed=60000
If speed<60000 Then
speed=speed+10000
20 End If
Pwm 1,speed,60000
Out 33,1
Delay 50
Loop
25 speed=0
Out 33,0
Pwmoff 1
Out 22,0 'turn fire led off
Out 21,0 'turn off retract led
30 extendonly=1
Incr cycnumfires
If cycnumfires>=255 Then cycnumfires=255
Eewrite ds,cycnumfires,1 'write the current cycle number of fires to the
eeprom
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Delay 200
End Sub 'return to the main routine
, -----------------------------------------------
'Abort fire
, -----------------------------------------------
Sub abortfire()
'Debug "Fire aborted before firing!! ",Cr
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(16,20)=0 '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
Eewrite ds+1,cycabortfires,1 'write the current cycle abortfires to the eeprom
Delay 200
homeextend 'extend to 1 cm
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 re-loadable,
interchangeable staple cartridges, such as the stapler 1 described herein, an
RFID can be
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47
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. RFIDs 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, the encryption device according to the
present
invention provides all of these desirable characteristics and limits the
undesirable ones.
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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 board or to the appropriate control electronics within the
handle of the
CA 02847464 2014-03-26
49
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 interchangeable part. 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 inserted within the end
effector; in one
particular embodiment, contact can be made only when the part is correctly
inserted.
The 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 communication 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 DS2432 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 D52460 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
D52460 chip
is placed in the handle, the low cost encryption characteristic is satisfied.
There exists an
alternative circuit configuration using two D52432 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 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 chip and one D52460 chip. The exemplary control circuit for the
encryption
CA 02847464 2014-03-26
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
5 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
10 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 DS2460
chips, the
15 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
20 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
25 the hash code reply transmitted from 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,
30 data regarding the time, date, environment, etc. and characteristics of
the unauthenticated
part can be stored for later or simultaneous transmission to the manufacturer
(or its agent)
to inform 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
CA 02847464 2014-03-26
51
messages 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 1 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 connected, the identity of the handle that fired the cartridge,
the time, date
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52
and other temporal data when use and/or connection occurred, how long it took
to fire the
cartridge, how many times 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 the
user 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
lithium-
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
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53
is being used in the text 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 both are designed to deliver the same
power over a
CA 02847464 2014-03-26
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54
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 devices
that are smaller
and lighter, not larger and heavier. Based upon these considerations, cost,
size, and weight
are factors that can be optimized for use in the surgical stapler handle of
the present
invention.
Available motors for use within a physician's hand include motors with
relatively
inexpensive ceramic magnets and motors with relatively expensive rare earth
(i.e.,
neodymium) 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 27.5 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 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 diameter motor. Unlike a standard motor, the
coreless motor
can have an efficiency of up to 80%. Coreless motors almost all use rare 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 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 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
CA 02847464 2014-03-26
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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
5 efficiency with the 82% drive train efficiency yields an overall
electrical to final
mechanical efficiency of approximately 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.
10 To generate the force necessary to meet the above-mentioned
requirements, the
power (in watts) of the mechanical assembly can be calculated based upon the
82 kg over
mm in 3 seconds to be approximately 16 Wafts. It is known that the overall
mechanical
efficiency is 49.2%, so 32.5 Watts is needed from the power supply (16 mech.
watts
32.5 elec. Watts x 0.492 overall efficiency.). With this minimum requirement
for
15 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
20 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
25 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
30 mechanical construction); and
= type and construction of the PTC (positive temperature coefficient of
resistance) device.
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56
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 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 load 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.
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57
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 left unchecked, the battery could heat to a
point where the
chemicals could 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 60 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/ies.
At the minimal
level (e.g., about 20% of peak current), the battery can cool off to a "safe"
level at which
CA 02847464 2014-03-26
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58
time greater power can be supplied. The partially conducting layer of the PTC
device is,
for example, a composite of carbon powder and polyolefin 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 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 level 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 for 4 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 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.
CA 02847464 2014-03-26
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59
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 rack (in inches per second ("IPS")) for
the 120#
and 180# loads 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
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 pack was able to move the load at about 0.4 IPS 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
CA 02847464 2014-03-26
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 turns 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
5 to be used, such that a lower number of turns results in a 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
10 (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 coreless 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 volts). The motors rated for 12 volts
output peak power
15 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
20 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
25 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
30 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
CA 02847464 2014-03-26
61
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
gear box. This leaves the final 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 - 1 revolution/second (rps); 1 rps @ 0.8 IPR 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 idealized
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.
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62
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 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 CR2s 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 PTC (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
CA 02847464 2014-03-26
=
63
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
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 180# 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
CA 02847464 2014-03-26
64
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 are 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 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. 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. In 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, polyisocyanates, polyurethane,
silicone,
vinyl, ethylene copolymer, expanded polyethylene, fluoropolymer, or styrofoam.
The
material can be an elastomer, such as silicone, polyurethane, chloroprene,
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
surrounding the motor/gear box. In a second embodiment, the motor and drive
train are
isolated within a nested box configuration, sometimes referred 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 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, sterilization of the handle components after use becomes an
issue.
Sterilization before use is also significant. Because the electric stapler
includes electronic
CA 02847464 2014-03-26
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 cost associated with
gas
5 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 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
10 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
15 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
20 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 environment 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
25 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
30 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-
CA 02847464 2014-03-26
66
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 cells(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 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 Current
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
CA 02847464 2014-03-26
67
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, 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 exemplary
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
CA 02847464 2014-03-26
68
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
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 blade 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
CA 02847464 2014-03-26
69
part 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 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. 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 switch 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 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 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 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
CA 02847464 2014-03-26
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 travel limit switch 1230 that
interrupts power
supply to the motor M and prevents further rearward travel, at least as long
as the switch
5 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 translates into a high rotational inertia. As such, when any
switch mentioned
10 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 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
15 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-
20 circuit utilizing a short-circuit property of an electrical motor. More
specifically, the
electrical motor M is placed into a short-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
25 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
30 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
CA 02847464 2014-03-26
71
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 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
CA 02847464 2014-03-26
. .
,
72
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.
The above-described embodiments should be regarded as illustrative rather than
restrictive. Accordingly, it should be appreciated that variations to those
embodiments can
be made by those skilled in the art without departing from the scope of the
invention as
defined by the following claims.
