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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to a fluid source cartridge and a pump tube mount
insertible into the cartridge.
It is an object of this invention to provide a cartridge and tube mount
which accurately position a tube within an infusion pump to permit the
automatic delivery of fluid at a precisely determined rate. It is
desirable that such accuracy be obtained using low cost plastic pieces.
When a cartridge is inserted into a peristaltic pump, the pumping fingers
must interact with the pump tube mounted in the cartridge to open and
close the tube completely Any warping of the cartridge or any
mispositioning of the tube may permit a leak when a finger is depressed
against the tube Any such leak would result in an inaccurate infusion
rate. Therefore, it is desirable that a cartridge and pump tube mount be
provided which accurately positions the pump tube in three dimensions.
The pump tube used in an infusion pump cartridge is preferably made from a
compressible material which is inert with respect to the fluids to be
delivered through the tube. Such an inert, compressible material very
often does not bond well with adhesives. Thus, in attaching such a tube to
a plastic mount, a common method was to provide a fitting with pointed
ridges projecting therefrom. The ridges would dig into the inner
circumference of the tube and hold it in place. This has the disadvantage
of possibly tearing the tube material. It is an object of the present
invention to provide a mount for such a tube which does not subject the
tube to tearing forces.
SUMMARY OF THE INVENTION
The present invention is directed to a fluid source cartridge and pump tube
mount insertible into the cartridge. The tube mount features an elongated
fitting having a cylindrical exterior portion and an indentation such as
an angular groove about said exterior portion. A tube of compressible
material is mounted on the fitting such that the exterior portion of the
fitting makes surface contact with the inner surface of the tube. A collar
surrounds the tube at the indentation. The collar can thus force the inner
circumference of the tube into the indentation to securely hold the tube
on the fitting.
The pump tube mount secures the tube between a front wall and a rear wall.
A rigid base is located beneath the tube to support the tube against the
pressure of the peristaltic pump fingers. The rear wall extends downwards
and has tabs extending therefrom so that the mount snaps into place when
the mount is properly installed into the cartridge. The tabs secure the
mount in place, once properly installed. The front wall of the tube mount
is uniquely shaped to match the shape of an opening in the cartridge. This
advantageously helps to insure that the proper mounts are being used in
the cartridge and to precisely locate the mount in the cartridge.
The fluid source cartridge itself is a housing with two end walls connected
by two side walls. The side walls have a top edge which form a fulcrum
between the portion of the cartridge bearing the tube mounts and the
remainder of the cartridge. Thus, advantageously when the cartridge is
locked onto the pump, rather than bowing the entire cartridge causing
inaccuracy in the relative position between the pump fingers and the tube,
bending is substantially limited to the portion of the cartridge behind
the fulcrum away from the tube mount section. The present invention
advantageously provides modularity such that the cartridge may support any
number from one to four fluid sources, it being only necessary to provide
the appropriate number of pump tube mounts in the cartridge.
Other objects and advantages of the present invention will become apparent
during the following description of the presently preferred embodiment of
the invention taken in conjunction with the drawings.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a pump with a cartridge of the present
invention.
FIG. 2 is a second isometric view of the cartridge of the present invention
illustrating its relationship with a pump.
FIG. 3 is a bottom plan view of a pump for use with the present invention
without the cartridge in place.
FIG. 4 is an end view of the pump of FIG. 3.
FIG. 5 is a side cross-sectional view of a pump and the cartridge of the
present invention.
FIG. 6 is a plan view of a cartridge of the present invention.
FIG. 7 is a side elevational view of the cartridge of FIG. 6.
FIG. 8 is an elevational view of the cartridge of FIG. 6 taken along lines
8--8.
FIG. 9 is a perspective view of a cartridge of the present invention along
with the pump tube mounts of the present invention.
FIG. 10 illustrates how a pump tube mount of the present invention is
inserted into the cartridge of the present invention.
FIG. 11 is an isometric view of the pump tube mount of the present
invention attached to a fluid source pouch.
FIG. 12 is a plan view of the pump tube mount of the present invention
without the tube and its retaining rings.
FIG. 13 is an elevational view of the pump tube mount of FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, a pump housing 10 is provided for pumping fluid
from a multiple fluid cartridge 20. The pump housing 10 is provided with a
liquid crystal display 12, a keyboard 14 and as shown in FIG. 4,
programming jack 16. The underside of the pump housing 10 forms a cavity
for receiving the cartridge 20. The cavity extends through one end of the
pump housing 10. At the open end of the housing, there are several
cartridge retaining holes 18 for engaging tabs 34 on the cartridge.
The cartridge 20 houses one or more pump tube mounts 24. Each pump tube
mount 24 is connected to a fluid source which is either stored in a bag or
a pouch in a fluid source portion of the cartridge or stored on a bag
hanging from an intravenous delivery pole. To connect with a bag hanging
from a pole, the cartridge's fluid source portion may have a window
through which lumens may be inserted to connect the bag with the tube
mount. Each pump tube mount 24 includes a compressible tube 22 made from a
material which is inert to the fluids which will be fed through the tube.
At the outer end of the pump tube mount 24, a luer connector 26 serves as
the outlet for delivering fluid into an output lumen.
Individual output lumens may be connected to each of the luer connectors
26. These lumens may remain separate or they may be fused together to form
a multilumen tube for outputting the fluid to a connector for making
connection with an implanted catheter, for example. The multilumen output
tube may be connected to any of a variety of multilumen connectors. Three
types of multilumen connectors are shown in the copending parent U.S.
patent application Ser. No. 216,512, filed on July 8, 1988 owned by the
same assignee as the present invention. The disclosure of said parent
application is hereby incorporated by reference herein. A needle connector
28 may be used in which each lumen is connected to a hollow injection
needle. The needle connector may be inserted through a silicone block to
make connection with a connector for a multilumen catheter. Another option
is a multilumen connector such as that described in co-pending U.S. patent
application Ser. No. 178,673 filed on Apr. 7, 1988, owned by the same
assignee as the present invention. The disclosure of said application is
hereby incorporated by reference herein. A third possibility for the
multilumen output tube is to connect each lumen separately to a luer
connector so that individual connections can be made to four separate
catheter lines.
An alternative connector for delivering fluids from the cartridge to a
patient may be a single lumen manifold 28 as shown in FIG. 1. The manifold
28 can be provided with four connectors 30 for securely attaching to the
luer connectors 26, extending from the cartridge. Each of these
connections may then lead to a single lumen 32. When this type of
connector is used, it is normal practice to make the fluid source furthest
from the manifold output a flushing solution With this arrangement, the
pump generally delivers one solution at a time or one fluid in conjunction
with the flushing solution Before switching from one solution to another,
the flushing solution is delivered to clean out the single lumen so as to
prevent intermixing of different fluid solutions. This would be necessary
in the case of drugs which are either incompatible or which cause
precipitation when mixed.
The cartridge 20 is provided with several positioning tabs 34 which extend
from the front end of the cartridge. The tabs 34 are inserted into the
holes 18 in the pump as shown in FIG. 2. The engagement of the tabs 34
with the holes 18 precisely positions one end of the pump interface
portion of the cartridge 20 with respect to the pump 10.
Moreover, by providing at least three tabs 34 spread across the front end
of the cartridge, the cartridge is supported across its entire width and
bowing of the cartridge is avoided. A cartridge 20 of the present
invention is preferably used with a pump having a key operated latch 36.
The lock 36 engages a tab 38 extending from the rear end of the cartridge
20. As will be discussed below in greater detail with respect to FIGS.
6-8, the cartridge 20 has the top edge 39 which forms a fulcrum 72 at the
rear of the pump tube mounts. The top edge 39 is bevelled from the fulcrum
72 near the rear of the pump tube mounts down to the rear end of the
cartridge 20. When the cartridge 20 is inserted it must be pushed up
against the pump. The latch 36 engages the tab 38 to lock the cartridge in
a pushed up position providing tension in the cartridge 20.
Advantageously, in accordance with the present invention, by locating the
fulcrum of the top edge behind the pump interface portion carrying the
pump tube mounts, the bending of the cartridge is substantially restricted
between the fulcrum and the rear end of the cartridge 20. The tension
provided by the lock provides a repeatable position for an inserted
cartridge and the fulcrum ensures that the entire pump interface portion
is secured flat against the pump. This is an important feature since if
the cartridge were permitted to bow away from the pump in the pump
interface portion, it is possible that one of the pump fingers would not
fully close off a pump tube as required to provide precision infusion
rates.
FIG. 2 illustrates flexible pouches 44 used as the fluid sources within the
cartridge 20. Each fluid source pouch 44 is connected to a pump tube mount
24. At present, the following procedure is suggested for using the
cartridges 20 when it is provided with empty pouches 44. The desired fluid
is injected into the connector outlet 26, using a syringe or other
conventional means. After filling the pouch 44 with the desired amount of
fluid, the connector outlet 26 is attached to the output line. When all of
the pouches are filled with their fluid, the cartridge may be inserted
into the pump housing 10 and a purge cycle may be run on each of the fluid
sources to pump out all of the air which may have gotten into the pouch or
pump tube. After purging the air, the cartridge 20 is ready for use in an
infusion.
Referring now to FIGS. 3 and 5, the presently preferred pump for use with
the present invention is provided with a plurality, four in this case, of
linear peristaltic pumps. The illustrated pump is a three finger pump,
called such because of the three cams which are repeatedly lowered and
raised to provide the desired pumping action Each pump thus activates
three cam followers, including an output valve 46, a pump plunger 48 and
an input valve 50. Power for the pump is provided by a battery pack which
may be loaded into a cavity behind a battery cover 52 alongside the
peristaltic pumps within the housing 10. Each pump is provided with its
own motor 54 which turns a cam shaft 56. The cam shaft 56 is provided with
a timing disk or encoder 58. The timing disk is solid except for a sector
which is removed. The disk can thus be read by an optical timing circuit
on a printed circuit board 60 to count the rotations, thereby controlling
the rate and location of the cam shaft 56.
To maintain improved accuracy, the cam followers should be made to always
press against the tube 22, even when in the open position. The pump tube
22 is supported relative to the cam followers by a rigid base 67. The
action of the fulcrum in the cartridge 20 ensures that the rigid base 67
is always positioned a fixed distance from the cam followers on the pump.
Pumping is performed as follows. With the pump plunger 48 and the input
valve 50 retracted, the output valve 46 is lowered to close off the fluid
conduits This permits the pump tube 22 to fill with fluid. This is the
preferred position whenever the pump is inactive. Next, the input valve 50
is lowered to close off the pump tube 22 and prevent fluid from flowing
back into the fluid source 44. The cam shaft is then turned permitting the
tube 22 to expand, pushing the output valve 46 to open. The pump plunger
48 is activated by the cam shaft to push fluid out of the tube 22 and
through the outlet 26. Then the output valve 46 is again closed. The pump
plunger 48 and the input valve 50 are permitted to open, thereby allowing
the pump tube to refill with fluid. Thus, fluid is pumped out of the fluid
source. The pump tube in the presently preferred embodiment has an inner
diameter of 0.030 inches, an outer diameter of 0.156 inches and a 50
durometer Shore A. The rate of pumping is controlled by knowing the
precise volume pumped in each cycle and monitoring the number of pumping
cycles per unit of time.
A programmable microprocessor is provided on a control circuit board 76.
Each of the four pump motors is controlled by the controller board 76.
Since each fluid source has its own pump and pump motor, the rate and
sequence of fluid infusion is entirely flexible. Infusions may take place
concurrently or sequentially and at any rate. The desired sequence and
rates of infusion are programmed into the controller board 76 through the
programming jacks 16. Thus, in accordance with the present pump, multiple
fluid infusion treatments may be delivered to a patient in any number of
sequences and rates. Thus, the pump provides physicians with great
latitude for selecting multiple-fluid drug regimens for treating patient
illnesses.
Referring now to FIGS. 6-8, the cartridge 20 of the present invention shall
be described in greater detail. FIG. 6, illustrates a cartridge 20 of the
type with a window 62. The window provides a hole through which lumens can
be fed to connect the pump tubes 22 with fluid sources. A discontinuous
dividing wall 64 separates the cartridge 20 into a pump interface portion
66 and a fluid source portion 68. The fluid source portion 68 may provide
fluids through a window such as that shown in FIG. 6. Alternatively, the
fluid source portion 68 may be filled with fluid source pouches 44. With
the pouches 44, the cartridge 20 can be used by an ambulatory patient. The
cartridge 20 with a window 62 permits the same pump apparatus to be used
by a hospital in-patient. Alternatively, the fluid source portion 68 of
the cartridge 20 can be made extra deep, as shown in FIG. 14, to provide
room for a drug solution mini-bag. Such a mini-bag provides more volume of
fluid than the pouches 44. The mini-bag of FIG. 14 includes an inclined
floor to help urge the fluid in the mini-bags towards the opening in the
bottom of the bag. As such, the pump apparatus can be used with the
mini-bags to provide a portable infusion apparatus which can be used by a
patient undergoing high fluid volume infusions in the home.
The tabs 34 secure one end of the pump interface portion of the cartridge
flat against the pump. The top edge of the cartridge 20 is flat from at
least the front end wall 70 to the dividing wall 64. Just beyond the
dividing wall 64 in the fluid portion of the cartridge, a fulcrum 72 is
formed by bevelling the top edge of the cartridge from the fulcrum down
towards a rear wall 74 of the cartridge. In accordance with the presently
preferred embodiment of the present invention, the bevelling results in a
drop off of 40 thousands of an inch from the top edge 39 at the dividing
wall 64 down to the top edge 39 of the end wall 74. When the cartridge 20
is inserted into a pump, the tabs 34 support one end of the cartridge
securely within the pump. The person inserting the cartridge pushes the
rear end of the cartridge against the pump so as to be able to close the
latch 36 to engage a tab 38 on the rear end 74 of the cartridge. The latch
36 on the pump is turned by a key to swing it onto the tab 38. The latch
36 lifts the tab 38 up towards the pump. In the latched position, the top
edge of the cartridge 20 at the end wall 74 is 20 thousands of an inch
away from the pump. Thus, the locked latch 36 applies pressure against the
rear end of the cartridge to bend it upwards 20 thousands of an inch from
its resting position. The tension travels back to the fulcrum 72 and
forces the fulcrum flush against the pump. Thus, all of the bending of the
cartridge 20 caused by the 20 thousandth displacement appears in the fluid
source portion. Consequently, with the fulcrum in a known repeatable
position, the pump interface portion on the other side of the fulcrum is
properly spaced relative to the pump and accurately positioned every time
the cartridge is inserted.
Also shown in FIG. 7 is a ledge 75 formed by the dividing wall 64. The
ledge 74 has an upper edge 77 at the level of the base of the pump
interface portion of the cartridge. The ledge 75 has a lower edge 78 or a
series of individual lower edges 78 which are provided for engaging the
pump tube mounts.
The end wall 70 has a series of uniquely shaped openings 80 which
accommodate the outlet ends of the pump tube mounts. Immediately behind
each opening 80 is a retaining stump 82. The opening 80 is shaped to
secure the front wall of the pump tube mount in two directions. The front
wall is prevented from moving up and down or left and right when installed
within the cartridge opening 80 Furthermore, the opening 80 is given a
unique shape as if it were a lock for a key. Just as a key may be uniquely
designed to fit into a lock, the front wall of a pump tube mount can be
uniquely shaped to fit the unique shape of the opening 80. This feature
helps to ensure that only the appropriate tube mounts are inserted into
the cartridge. The retaining stump 82 prevents the wall from moving back
into the cartridge. The final direction of freedom is secured by the
interaction of the rear wall of the pump to mount with the ledge 75 of the
cartridge.
The front wall 84 of a pump tube mount can be seen in FIG. 9. Extending
from the front wall 84 is an outlet 26 which is preferably a female luer
connector. Two side walls 86 connect the front wall 84 to a rear wall 88.
The rear wall 88 of the pump tube mount extends downward below the base 67
of the pump tube mount. At the lower end of the rear wall 88 are a pair of
tabs 90 which engage the lower edge 78 of the ledge 75 in the cartridge
20. The dividing wall 64 in the cartridge 20 is discontinuous providing
openings for each of the pump tube mounts. Also illustrated in FIG. 9 is a
bag spike 92, which is inserted into a bag of fluid solution hanging from
a pole to connect the pump with the fluid solution.
FIG. 10 shows how a pump tube mount of the present invention is inserted
into a cartridge of the present invention. The rigid base 67 beneath the
pump tube 22 does not extend all the way to the front wall or the rear
wall. At the front wall, this provides a space into which the retaining
stump 82 can be extended. Thus, the first step, is to position the front
wall 84 up against the stump 82. The rear wall 88 is then lowered over the
ledge 75 in the cartridge 20. As the rear wall 88 is lowered, the front
wall 84 pivots into place within the opening 80. The rear wall 88 is
lowered until the tabs 90 snap into the openings beneath the lower edge
78. The rear wall 88 is located so as to fit snugly against the ledge 75.
Thus, when the tabs 90 have not yet been lowered into the openings beneath
the edge 78, the tabs 90 are forcing the rear wall 88 away from its normal
resting position. Once the tabs get beneath the lower edge 78, the rear
wall 88 is free to resume its resting position and therefore springs back
against the ledge to make a snapping noise. The snap can be heard and felt
so as to reassure the user that the pump tube mount is correctly
positioned. The engagement of the tabs and the lower edge 78 keeps the
pump tube mount in its correct position When in place, the rear wall 88
against the ledge 75 prevents the pump tube mount from moving forward.
Thus, in combination with the retaining stump 80 and the opening 88, the
pump tube mount is securely held in a known position in three dimensions.
FIG. 11 illustrates a disposable pump tube mount of the present invention
The pump tube mount shown is attached to a flexible fluid source pouch 44.
The fluid source pouch 44 may be adhesively bound to an inlet 94 extending
from the rear wall 88 of the pump tube mount. A luer cap 96 may be screwed
on to the luer connector 26 when the tube mount is not hooked up to an
output line.
In FIG. 12, the pump tube mount is shown without a tube 22. Extending
inwards from the front wall and the rear wall 88 is a fitting 98. The
fitting 98 has a cylindrical exterior portion which makes surface contact
with the inner circumference of the tube 22. The surface contact provides
a frictional force between the fitting 98 and the inner circumference of
the tube 22. In certain applications, this frictional force may be
sufficient to hold the tube on the fittings. Since it is desirable in an
infusion pump application to use a compressible material for the tube 22
which does not adhere to the fluids being delivered, it is often also true
that such materials do not adhere to adhesives. Therefore, adhesive
bonding is not a suitable means for attaching the tube to the fitting.
The presently preferred material for the tube 22 is Dow Corning
medical-grade silicone.
In accordance with the present invention, an indentation such as an annular
groove 100 is made in the cylindrical fitting 98. If the tube 22 fits
tightly enough over the fitting 98, the silicone will slightly extend into
the groove 100. This will provide an edge against the fitting which will
hold the tube in place. To ensure that the silicone is depressed into the
groove 100, a collar 102 may be placed over the tube concentrically
aligned with the groove 100. The engagement of the tube with the groove
provides adequate resistance against the shear forces created by the
pumping action. The collar 102 is preferably a rigid material which is
sized to compress the silicone into the groove 100. The collar 102 may be
made from a material such as PVC.
Referring now to FIG. 13, the rigid base 67 is shown. The base 67 is
supported by the sidewalls 86 of the pump tube mount. As can be seen in
FIG. 13, there is a space between the rigid base 67 and the front wall 84
into which the stump 82 can extend.
The pump tube mount advantageously provides a means for securing a silicone
tube to a fitting without adhesive or outwardly projecting ridges which
may subject the silicone to tearing. The mount is accurately positioned
within the cartridge in three dimensions. Moreover, the fulcrum of the
cartridge ensures accurate spacing between the pump and the pump interface
portion of the cartridge to permit accuracy in infusion pump rates.
Of course, it should be understood that various changes and modifications
to the preferred embodiment described above will be apparent to those
skilled in the art. For example, any number of different front wall shapes
and corresponding openings may be used in the front end wall of the
cartridge to achieve the two dimensional accuracy of the present
invention. Also, the cartridge of the present invention need not be
restricted to use with four pump tube mounts, any number may be provided
including a single fluid cartridge and pump. These and other changes can
be made without departing from the spirit and scope of the invention and
without diminishing its attendant advantages. It is therefore intended
that such changes and modifications be covered by the following claims.
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