U.S. patent number 3,685,697 [Application Number 04/792,059] was granted by the patent office on 1972-08-22 for portable infusion pump.
This patent grant is currently assigned to Lear Siegler, Inc.. Invention is credited to Joseph H. Caslow, Melvin F. Huber, John A. Wootten.
United States Patent |
3,685,697 |
Caslow , et al. |
August 22, 1972 |
PORTABLE INFUSION PUMP
Abstract
A portable infusion pump for constantly injecting therapeutic
fluids into the human body at low positive pressures which has at
least one piston for forcing the therapeutic fluid out of its
associated fluid containing bag. The piston is moved by a constant
force spring which spring is controlled by a timing device.
Inventors: |
Caslow; Joseph H. (Avon Lake,
OH), Huber; Melvin F. (Grafton, OH), Wootten; John A.
(South Euclid, OH) |
Assignee: |
Lear Siegler, Inc. (Santa
Monica, CA)
|
Family
ID: |
25155668 |
Appl.
No.: |
04/792,059 |
Filed: |
January 17, 1969 |
Current U.S.
Class: |
222/137; 222/333;
222/386.5; 604/135; 604/214 |
Current CPC
Class: |
A61M
5/148 (20130101) |
Current International
Class: |
A61M
5/145 (20060101); A61M 5/148 (20060101); A61m
005/20 () |
Field of
Search: |
;222/137,333,386.5,390
;128/DIG.12,218A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Reeves; Robert B.
Assistant Examiner: Handren; Frederick R.
Claims
What is claimed is:
1. A small volume, positive pressure, self-contained, portable
infusion pump comprising at least one fluid containing collapsible
receptacle, fluid passage means in communication with said
receptacle and adapted for body hookup, force applying means
associated with said receptacle for collapsing said receptacle to
move fluid from said receptacle into and through said fluid passage
means, a constant force coil spring drivingly connected to said
force applying means, a torque and timing motor, and a slip clutch
drivingly connecting said torque and timing motor to said force
applying means to regulate the rate at which fluid is moved from
said receptacle.
2. An infusion pump according to claim 1 wherein said fluid passage
means comprises a check valve in open communication with said
receptacle, an L-shaped arm member having a bore in open
communication with said valve, a plug member adapted to permit
flushing of said bore, and connector means for connecting said pump
to body hookup tubes.
3. An infusion pump according to claim 2 wherein said receptacle
comprises an open ended bag of resilient thermoplastic material,
said open end being provided with an annular flange, a retaining
ring surrounding said open end and said flange, and a closure
member connected to said arm member and adapted to retain said
flange within said ring.
4. An infusion pump according to claim 1 wherein two receptacles
are contained within said housing and each receptacle is provided
with fluid passage means and force applying means.
5. An infusion pump according to claim 4 wherein said force
applying means comprises a piston adapted to contact its associated
receptacle to collapse the same thereby forcing fluid contained
therein into and through said fluid passage means, means connecting
said pistons for simultaneous movement into contact with said
receptacles, said means being operatively connected to said
spring.
6. An infusion pump according to claim 5 wherein said piston
connecting means comprises a plate portion having means at its
extremities to be connected to said pistons, a hollow central
embossment extending from said plate portion, a screw connected to
said spring and adapted to be rotated thereby and a screw drive nut
non-rotatably retained within said embossment and operatively
connected to said screw whereby rotation of said screw moves said
screw drive nut along the shaft of said screw thereby moving said
piston connecting means and said pistons.
7. An infusion pump according to claim 1 wherein said torque motor
comprises a battery operated electric watch mechanism operatively
connected to said slip clutch.
8. An infusion pump according to claim 6 wherein means are provided
to prevent rotation of said slip clutch.
9. An infusion pump according to claim 6 wherein rotatable means
are provided for manual engagement with said screw for priming and
rewinding said pump.
10. A small volume, positive pressure, self-contained, portable
infusion pump comprising a housing having at least one fluid
chamber, fluid passage means in communication with said chamber and
adapted for delivery of the contents from said chamber,
displacement means cooperating with said chamber for expelling the
contents thereof through said fluid passage means, a driving motor
operatively connected to said displacement means for supplying a
driving force thereto, a constant speed timing motor connected to
said displacement means for controlling the displacement thereof by
opposing and aiding said driving motor to maintain a constant rate
of displacement of said displacement means and thus provide a
constant rate of discharge of the contents of said chamber.
11. A small volume, positive pressure, self-contained, portable
infusion pump comprising a housing, at least one fluid containing
collapsible receptacle in said housing, fluid passage means in
communication with said receptacle and adapted for delivery of the
contents from said receptacle, displaceable piston means for
collapsing said receptacle and expelling the contents thereof
through said fluid passage means, a constant force spring
operatively connected to said displaceable piston means for
supplying a constant displacement producing force thereto, a timing
means associated with said displaceable piston means and said
constant force spring for controlling the release of the constant
force to said displaceable piston means to maintain a constant rate
of displacement of said displacement means and thus provide a
constant rate of discharge of the contents of said receptacle, said
timing means being connected to said displaceable piston means to
permit control of the displacement thereof by opposing and aiding
said constant force spring.
Description
BACKGROUND OF THE INVENTION
This invention relates to new and useful improvements in portable
infusion devices and more particularly to a low pressure, constant
and positive force, high reliability, unobtrusive, portable
infusion pump adapted for such purposes as ambulatory therapeutic
drug infusion over an extended period of time.
Various devices have been proposed in the prior art by which
therapeutic fluids have been injected into the human body over an
extended period of time. As for example, a rotary pump powered by a
watch has been utilized to squeeze the tube of therapeutic fluid in
order that the fluid might be forced into the body of the person
carrying the portable infusion device. Such devices have not proven
entirely satisfactory because of the difficulty in controlling the
rate of flow from the devices, and the low reliability inherent in
such designs.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a
portable therapeutic fluid infusion pump that over an extended
period of time will maintain a constant rate of flow of fluid from
the pump. A further object of this invention is to provide a
portable infusion pump that is positively controlled to insure the
systematic injection of fluid into the human body. A further object
of this invention is to provide a portable infusion pump for
constant injection of therapeutic fluids into the human body which
pump may be readily refilled at the end of a prescribed period of
time. Another object of this invention is to provide a lightweight
and thoroughly portable but accurate infusion device. A further
object of this invention is to provide a means to facilitate
sterilization of the collapsible fluid receptacle and refilling of
the collapsible fluid receptacle.
This invention contemplates a portable infusion pump consisting of
a housing containing at least one collapsible fluid receptacle.
Means are provided in association with the receptacle to provide
for passage of fluid from the receptacle to appropriate connections
to the human body. A force applying device is contained within the
housing to collapse the receptacle and force the fluid through the
fluid passage. The force applying means is operated by a constant
force spring connected through a preloaded slip clutch to a torque
motor.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a cross-sectional side elevational view of the infusion
pump of this invention with the pump in its fully loaded
position;
FIG. 2 is a partial cross-sectional view of the pump of FIG. 1 but
illustrating portions of the pump in its substantially emptied
condition;
FIG. 3 is a front elevational view of the device of this invention
with a portion broken away; and
FIG. 4 is a rear elevational view of the device of this
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings wherein the preferred embodiment is
illustrated, reference numeral 1 denotes the housing for the
infusion pump of this invention. The housing 1 is substantially
rectangular in cross section along its major axis and elliptical in
cross section along its minor axis. The housing defines a
substantially correspondingly shaped cavity 2 to contain various
components of the infusion device or pump of this invention. The
front end 4 of the housing 1 is provided with a separately formed
or integrally cast partition 3 defining with the housing two spaced
apart cylindrical bores 10. The partition 3 extends partially into
the cavity 2 and it is provided with a central bore 5 relieved near
its end 6 to provide a counter bore 7 and the opposite end 8 of the
partition 3 is relieved to provide a counter bore 9, the function
of which will be hereinafter explained. The internal diameters of
the counter bores 7 and 9 are greater than the internal diameter of
the bore 5.
The front end 6 of the partition 3 is provided with an externally
threaded portion 11 whose function will be hereinafter explained. A
pair of annular grooves 12 are provided on opposite sides of the
end 8 of the partition 3 and spaced inwardly from the bores 10. A
seal 13 is retained in each of the grooves 12 to provide
appropriate sealing as will be explained hereinafter. The bores 10
near the front end 4 of the housing 1 are relieved to provide
enlarged openings 24 and shoulders 14.
In order to retain the supply of therapeutic fluid or serum in the
infusion device of this invention, two serum bag assemblies 15 are
positioned within the bores 10 of the cavity 2 adjacent the front
end 4 of the housing 1. A serum bag assembly 15 is positioned on
opposite sides of the partition 3. The serum bag assembly 15
comprises a serum bag 16 of suitable resilient material, having an
annular lip 17 defining an open mouth 18. The lip 17 is backed by a
washer and retained between a shoulder 20 of an internally threaded
nut 21 and an annular externally threaded cap 22. The nut 21 is
dimensioned to come to rest against the shoulder 14 to retard
inward movement of the serum bag assembly into the housing.
In order to prevent accidental dislodgment of the two serum bag
assemblies 15, a bag cover 25 of substantially the same dimensions
as the cross-sectional area of the housing 1 is secured to the
housing by a threaded nut 26 secured to the threaded portion 11 of
the front end 6 of the partition 3. The cover 25 is provided at
both ends with a keyhole shaped slot 29, the function of which will
be hereinafter explained.
The serum or therapeutic fluid contained in each of the serum bags
16 is dispensed through a check valve 27 aligned with a central
opening 28 in the cap 22. This opening 28 is in open communication
with the interior of the bag 16. The check valve 27 in the
illustrated embodiment comprises a nipple shaped body 30 having an
annular flange 31 at its upstream end and a slit-like opening 32 at
its downstream end. The valve 27 is formed of rubber or other
suitable resilient material and the resiliency of the material
insures that the opening 32 is closed except when the fluid is
being forced out of the bag 16 as will be hereinafter
explained.
The check valves 27 are retained in alignment with the opening 28
by a hollow cylindrical stem member 33. The threaded end 34 of stem
member 33 is turned into tapped opening 35 centrally located in the
cap 22 and end 34 engages the flange 31 of the check valve 27
holding it in proper position. The nipple 30 of the valve extends
into the interior or bore 36 of stem member 33. The other end 37 of
the stem member is closed with a rubber plug 38 having a plug
portion 40 pressed into the other end 37 of the stem member and a
sleeve portion 41 surrounding the exterior of the end 37 to seal
that end of the stem member.
In order to provide for the flow of serum or fluid out of the stem
member 33, three grooves 42 are provided on the exterior surface of
the stem member intermediate its ends. The two outer grooves are
provided with O-rings 43 and the inner groove 42 is provided with
an opening 44 in open communication with the bore 36 of the stem
member 33. An arm member 45 is affixed to the stem member 33 by a
sleeve portion 46 surrounding the three grooves 42, thereby
bringing the O-rings 43 into sealing engagement with the interior
of the sleeve portion 46. A retaining ring 49 holds the arm member
rotatably affixed to the stem portion 33.
In the illustrated embodiment, the arm member 45 is L-shaped in
configuration with the sleeve portion 46 at one end. The arm member
45 is provided with a central bore 47 aligned with the central
groove 42 to provide open communication with the bore of the stem
member 33. The end of the arm member 45 opposite the sleeve portion
46 is provided with a connector 48 for suitable connection to body
hookup tubes (not shown).
The serum is forced out of bags 16 by a pair of pistons 50 movably
positioned within the housing 1. The face or forward end 51 of each
piston 50 is located adjacent to and in contact with the bottom 52
of its associated bag 16. In the event that fluid escapes from the
bags 16, it is prevented from escaping into the cavity 2 and about
each piston 50 by the seals 13 that are maintained in sealing
engagement with the outer periphery of the piston 50. Seals 13 each
preferably comprise a low friction slip ring element backed by a
resilient O-ring.
To provide for movement of the pistons 50, a boss 54 is provided on
the end of each piston opposite the face 51. The bosses 54 are
secured to a piston guide 55 by retaining rings 56 in order that
the two pistons 50 will be advanced and retracted in unison. THe
piston guide 55 comprises a plate portion 57 having openings 58
near Its outer extremity to receive the bosses 54 of the pistons.
The plate portion 57 is provided with a centrally located
embossment 60 having an opening 61 in its end remote from the plate
portion and a central bore 62 of larger diameter than the opening
61.
In order to move the piston guide 55 and its associated pistons 50
to force the serum from the bags 16, a screw drive nut 63 is
secured by conventional means to the embossment 60 and located
within its bore 62. The screw drive nut 63 engages a screw 64
extending centrally through the screw drive nut 63 and the opening
61 in the embossment 60. The forward end 65 of the screw 64 is
journaled in a bearing 66 located in the bore 5 of the partition 3.
The shaft 67 of the screw is secured to a driving drum mechanism 68
in conventional manner. The shaft 67 is also journaled in a bearing
70 which bearing is positioned in an opening 71 in the endplate 72
closing the end of the cavity 2 of the housing 1 opposite the cover
25.
The driving drum mechanism 68 is driven by a constant force double
coil spring 73 having one coil wound around and affixed to the drum
68 and the other coil wound around and affixed to a storage drum
74. The spring 73 is constructed and arranged to apply a constant
turning force to the drum 68 as it unwinds from the storage drum 74
and onto the driving drum. The storage drum 74 is rotatably mounted
on a spindle 75, which spindle is rotatably affixed to and extends
between the end plate 72 and the motor housing 76. The spring is
rewound on the storage drum 74 during the rewinding operation to be
explained hereinafter.
During operation of this device, various forces may retard movement
of the pistons that force fluid out of the serum bags, as for
example, friction between the pistons 50 and the seals 13. Since
these forces are not constant and the spring 73 is a constant force
spring, a torque and timing motor 78 is connected to the driving
drum 68 being driven by the spring 73. Torque and timing motor 78
runs at a constant speed. In the illustrated embodiment, the torque
and timing motor 78 is an electrically operated watch of
conventional design, the hour hand mechanism 78 a of which is
connected to a conventional slip clutch 80. One portion 79 of the
clutch is connected to the hour hand mechanism 78 a and the other
portion 79 a is connected by a tongue and groove arrangement 88 to
the driving drum 68. The tongue and groove connection is maintained
in releasable engagement by compression spring 88 a acting between
portions 79 and 79 a of the clutch. The slip clutch 80 is set to
slip or release at a preset torque value to prevent damage to the
watch 78 during manual resetting and rewinding operations of the
pump and to provide a positive driving connection between torque
and timing motor 78 during normal pumping.
Constant force spring 73 exerts a constant torque on the driving
drum 68 and, thus, on the screw 64. The applied torque tends to
turn screw 64 in a direction to cause pistons 50 to expel the
contents of bags 16. The drum 68 being connected to the torque and
timing motor 78 through the slip clutch 80 will turn only at a rate
determined by the torque and timing motor. Thus, the motor 78 tends
to slow down the free rotation rate of the drum 68 due to the
applied torque of spring 73 to the desired controlled rate of
rotation. In the event that the forces exerted on the pistons 50
and the screw 64 are such that the spring does not rotate the drum
at the desired rate, then the torque motor will provide the
necessary increase in force to maintain the desired rate of
rotation.
In order to return the pistons 50 to their original positions as
shown in FIG. 1, to rewind the spring 73 and to prime the pump, a
reset knob assembly 81 is positioned in the bore 5 of a partition 3
and spaced from the forward end 65 of the screw 64. The reset knob
assembly comprises a shaft 82 extending into the bore 5 and having
a slotted end portion 83 adapted to engage the end 65 of the screw
64. Except during resetting and rewinding, however, end portion 83
is spaced from the end of the screw 64. The other end of the
assembly is provided with a turning knob 84 to impart rotation to
the reset knob assembly when desired. During resetting and priming,
the knob assembly 81 is pushed inwardly toward the screw 64 to
engage the slotted end portion 83 and the end 65 of the screw 64.
As indicated in FIG. 3, the resetting of the infusion pump is by
rotation of the reset knob 84 in a clockwise direction. The priming
is by rotation of the reset knob 84 in the counterclockwise
direction. Inward movement of the shaft 82 of the reset knob
assembly 81 is retarded by a ball detent 99 extending through the
wall of the partition 3 and into contact with the shaft 82 of the
reset knob assembly 81.
In order to prevent damage to the torque motor 78 during hand
rotation of the screw during rewinding and priming, a locking screw
85 is threaded into and through a threaded opening 86 in the motor
housing 76. The screw 85 is provided with a pin portion 89 adapted
to be forced into contact with the portion 79 of the slip clutch 80
to prevent its rotation and thus movement of the hour hand
mechanism 78 a of the torque motor 78. Manual winding is permitted
by the release of slip clutch 80. The electrical plug 90 is removed
to stop the torque and timing motor 78.
As shown in FIG. 1, the infusion device of this invention is in its
fully loaded condition. In operation, the locking screw 85 is
screwed into the motor housing 76 until the pin portion 89 contacts
the portion 79 of the slip clutch 80 in order that any rotation of
the screw 64 will not be transmitted to the torque and timing motor
78, thereby preventing any possibility of damage to the motor.
Flushing fluid is injected by a needle (not shown) through the plug
portion 40 of each rubber plug 38 to flush out the bore 36 of the
stem member 33 and the bore 47 of the arm members 45 to insure that
the same are cleared of any air.
The cover 87 for the turning knob 84 is removed and the knob 84 is
pushed inwardly into the counter bore 7 and toward the screw 64
until the slotted end 83 contacts and mates with the end 65 of the
screw 64. The knob is rotated counterclockwise to turn the screw 64
causing the screw drive nut 63 to move toward the end 65 of the
screw 64 because it is prevented from rotating by a conventional
connection to the piston guide 55. Since the screw drive nut is
retained within the bore 62 of the embossment 60 of piston guide
55, any movement of the nut along the screw is transmitted to the
embossment and thus to the piston guide 55, thereby moving it
toward the serum bags 16. The pistons 50 are thus further advanced
into the bottoms 52 of the serum bags. The pressure exerted on the
bags forces fluid through the nipples 30 of the check valves 27 and
into the bores 36 of the stem members 33 and into the bore 47 of
the arm members 45. When fluid is observed leaving the connectors
48, the device is ready to be connected in conventional manner to
body hookup tubes.
After connection to the tubes, the turning knob 84 is withdrawn
from contact with the screw 64 and is returned to its position as
shown in FIG. 1. The cover 87 is then replaced to prevent
accidental movement of the turning knob 84.
In order to place the infusion device of this invention on
automatic operation, the locking knob 85 is unscrewed to release
the portion 79 of the slip clutch and the electrical plug 90
controlling the torque and timing motor is inserted. At this point,
the torque and timing motor 78 and constant force spring 73 assume
control of the rotation of the driving drum 68. Constant force
spring 73 exerts a constant torque on the drum 68 and the torque
and timing motor 78 maintains a constant rate of rotation of the
drum. Depending upon the forces opposing the advance of pistons 50,
the turning motor 78 may oppose or augment the torque provided by
constant force spring 73 as necessary to maintain a constant rate
of rotation of the screw 64 and, thus, a constant rate of advance
of pistons 50.
Rotation of the drum and thus the screw 64 which is connected
thereto moves the pistons 50 further into the serum bags 16,
thereby forcing the serum out of the bags and into the body hookup
tubes as previously explained. The spacing between the pistons 50
and the cavity 2 of the housing 1 is such that the bags roll back
along the pistons 50 as is shown in FIG. 2.
The pistons 50, the piston guide 55 and the embossment 60 continue
to move toward the partition 3 with the embossment being received
within the bore 9 of the partition 3 until the embossment travels
to the end of the bore 9. At such time, the pistons 50 will have
substantially emptied the two serum bags 16 and the unit is ready
for re-operation.
In the illustrated embodiment, the two bags 16 contain 12.5 cc of
fluid each and the device is set to operate at a speed and pressure
to force 2.50 cc from each bag per 24-hour period. Thus, the
infusion pump as illustrated will inject 5 cc of fluid per 24 hours
into the human body and the pump will operate without refilling for
5 days. When the bags 16 have been emptied, the cover 87 of the
reset knob assembly is removed. The nut 26 holding the bag cover 25
in place is removed and the arm members 45 are aligned with the
keyhole slots 29. Thereafter, the cover 25 may be removed from the
housing, permitting removal of each serum bag assembly 15 and
replacement of new assemblies by removing the nut 21 thereby
releasing the bags 16. A new bag or a refilled bag may then be
replaced and the assembly is ready for insertion into the proper
position in the housing 1.
The removability of the bags 16 and fluid passages provides a
particularly advantageous feature of this invention. The bags can
be conveniently sterilized separately from the rest of the pump.
Thus, the sterile conditions of the fluid containers and ducts can
be easily and conveniently insured without having to attempt
sterilization of the entire mechanism. Also, the pump can be
quickly and completely emptied of its fluid contents and/or the
contents changed and replaced.
Before the bag assemblies are replaced, the locking knob 85 is
brought into contact with the portion 79 of the slip clutch. The
turning knob is then pushed into contact with the screw 64 and
rotated clockwise to return the pistons 50 to their original
positions. Rotation of the screw 64 rotates the driving drum 68 and
unwinds the constant force spring 73 therefrom and rewinds it onto
the storage drum 74. The bags and cover 25 are then replaced and
the pump is ready for another start-up operation as hereinbefore
explained.
This invention also comprehends a particular form of the preferred
embodiment described above. This modified form comprises the device
as shown and described above, but with a conventional escapement
mechanism substituted for torque and timing motor 78. This provides
a fluid delivery system having high reliability and accuracy
resulting primarily from the combination of the constant force
motor powering the pump and for driving the escapement. In this
embodiment, the constant force motor provides a torque for powering
the pistons and for driving the escapement which torque remains
substantially constant at all times irrespective of the amount of
energy stored in the spring. The constant force on the piston or
displacement means contributes to the maintenance of a constant,
though often very low, delivery rate even when the bags are nearly
empty and the stored energy of the spring is almost exhausted. It
also insures at all times the accuracy of the timing function
performed by the escapement mechanism, and thus the overall
accuracy and constancy of the rate of fluid delivery from the pump
throughout the dispersing of an entire charge. Such results are
often vital to the user of these devices.
It will be recognized that in both the preferred and modified
embodiments of this invention, the rate of fluid delivery of the
device can be easily varied in several ways. First, the speed of
the screw stem can be selected to provide the desired rate of
advance of a given size piston. Second, the lead of the screw can
be varied; and, finally, the working area of the pistons and
cooperating bags can be varied. Further, all of the cooperating
sets of bags and pistons in each device need not be the same
diameter; and, by using different diameters, differential
quantities of different fluids may be simultaneously delivered.
It can be seen from the foregoing that the infusion device of this
invention provides for the constant feeding of serum or other
therapeutic fluid irrespective of changes in force exerted on the
device, thereby insuring a constant flow of fluid from this device.
It should be understood that various modifications of the preferred
embodiment described herein may be made without departing from the
spirit and scope of the appended claims.
* * * * *