Note: Descriptions are shown in the official language in which they were submitted.
~ 73~ 557-2861
Backqround of the Invention
The United States Patents listed above describe a device
for dispensing fluid at a slow, uniform rate over a sustained
period of time which has a simple, inexpensive structure, is easy
-to use, requires no regulation or adjustment by the person using
the device, and which is well-safeguarded against tampering or
inadvertent improper operation of the device.
The dispensing device described therein comprises a hose
assembly adapted to be coupled to a conventional syringe, which
hose assembly comprises a length of capillary tubing through which
the fluid must pass while being delivered to a patient~ and means
for applying a uniform force to the plunger to provide fluid flow
through the capillary tube at a slow, steady rate over a long
period of time (e.g., less than 60 milliliters per hour).
As stated therein the rate of flow Q in cc/sec through
the capillary tuhe can be estimated from Poiseuille's Law
expressed in the equation:
Q 81n
,, ~
( ~,, .
` ~ -2 ~ 2
where P is the pressure drop through the tube in dynes/cm2,
r is the internal radius of the capillary tube in cm, 1 is
the length of the capillary tube in cm, and n is the liquid
viscosity in poise. By solving this equation it can be
found that capillary tubes of a reasonable length suitable
for restricting flow to rates in the range indicated under
the influence of pressures of the range of pressures easily
developed in a syringe (e.g., about 69,000 to 2,068,400
dynes/cm2) can have bores in the range of about 0.0025 to
0.038 cm. With current technology it is difficult to
produce capillary tubing in this size range with bore
diameters which deviate less than about 10~ from a nominal
diameter, however. Since the rate of flow through a tube
is proportional to the fourth power of its diarneter, such a
deviation could cause a variation of about -3~% to +~6% in
flow rate, which would be unacceptable for most medical
uses. By only using long lengths of capillary tubing,
however, (i.e., capillary tubes over 2 centimeter in
length) much less variation in flow rates is found between
different lengths of capillary tubing than is suggested
above; perhaps because diameter variations tend to cancel
each other along the length of the capillary tubes. With
capillary tubing of polytetrafluoroethylene sold under the
~ trade ~ "Teflon" (which is preferred) having a
nominal inside diameter in the range of 0.0025 to 0.019 cm,
it has been found that lengths of the capillary tubing in
excess of 2 cm. normally produce flow rate variations of
less than 10%, which is acceptable for medical use of the
device described herein.
Hose assem'olies having capillary tubes of
different nominal diameters which afford different rates
of fluid flow (which rates, for example, may be indicated
by color coding of the hose assemblies) can be used
interchangeably in the device, and the inexpensive hose
assemblies can be clisposed of after use to insure
sanitation for medical or other uses.
~73~;~
One problem presented by the use of such a hose
assembly is that in many instances (such as for use in
introducing fluids intravenously) prior to activating the
device, air must be purged from the hose assembly to
preclude air being delivered to the patient. This purging
is typically done by attaching the hose asssembly to the
syringe outside of the device, and manually activating the
syringe until liquid has entirely filled the hose assembly;
after which the syringe is placed in the device and the
device is activated to deliver the liquid to the patient at
the desired rate.
U.S. Patent No. ~,430,079 teaches that for hose
assemblies having small diameter capillary tubing (e.g.,
0.0045 to O.Ol cm) adapted to allow only very slow rates of
flow (e.g. 0.5 to 15 ml/hr) it is preferred to use a first
embodiment of the hose assembly that allows the capillary
tubing to be bypassed to afford rapid purging of air from
the hose a~sembly with fluid from the syringe. The first
hose assembly embodiment includes a metering assembly that
provides a coupler between the hose assembly and the
syringe. The metering assembly includes the capillary tube
and parts moveable between a metering position at which
fluid flowing through the metering assembly must pass
through the capillary tubing, and a purging position at
which fluid propelled by manual operation of the syringe
can bypass the capillary tube and flow rapidly through the
metering assembly to purge the hose assembly. The device
has structure that insures that the metering assembly in
this first embodiment of the hose assembly is in its
metering position when the dispensing device is activated
to preclude operation of the device with the metering
assembly in its purge position. Support means included in
a frame for the device supports the meterin~ assembly and
thereby a syringe couple~ to the metering assembly. The
support means is specially adapted so that it will engage
and support the metering assembly only when it is in its
metering position.
:,
~Z2~
--4--
Also U.S. Patent No. 4,430,079 teaches that for
metering devices having larger diameter capillary tubing
(e.g. over 0.010 cm) adapted to allow relatively larger
rates of flow (e.g. over 15 ml/hr) one oE several other
embodiments of the hose asssembly can be used that have no
by pass, in which embodiments the capillary tubing may be
positioned at the end of the hose assembly opposite the
syringe. ~hen the capillary tubing is positioned at the
end of the hose assembly opposite the syringe almost all of
the air passes through the capillary tube before the liquid
reaches it, which, because of the extremely low viscosity
of air compared to liquid, allows a fairly rapid purge rate
~e.g. less than about 20 seconds). These other embodiments
of the hose assembly include more conventional couplers at
their ends adapted to engage the syringe, which couplers
are adopted to be received in the support means of the
device.
When either of the above described types of hose
assemblies is made in a long length (e.~., over 45
centimeters and preferably in the range of 120 to 150
centimeters), however, it has a relatively large internal
volume (e.g., 1/2 to 3/4 cubic centimeter) which is quite
significant compared to the vol~lme of the syringe from
which the liquid is dispersed. Thus persons filling the
syringe must add additional liquid to allow for the volume
in the hose assembly (which will normally be still filled
with the liquid when it i9 disgarded after use) ~hile
providing the intended delivered volume of liquid. This is
both wasteful of the liquid, and causes an element of
uncertainty in forecasting what internal volume the hose
assembly wlll have.
Summary of the Invention
The invention claimed in this application
provides long leng~h ho~e assemblies that can e~fectively
meter dispensing liquid flow from the device de~cribed
above without containin~ a signiEicant internal volume oE
~2~73~
-5- 557-2861
liquid that must be accounted for in filling of the syringe.
According to the present invention there is provided a
hose assembly adapted for use with a fluid dispensing device which
applies a generally constant pressure to dispense fluid through
the hose assembly, said hose assembly comprising a capillary tube
having first and second ends and defining a through passageway
between said ends, said capillary tube having a volume of less
than about 0.25 cubic centimeter and a length of at least 45
centimeters; and said hose assembly further including a coupler at
said first end adapted for releasably attaching caid hose assembly
to a said device with an outlet opening of the devlce communicat-
ing with said through passageway.
Surprisingly, such capillary tubes can be quite quickly
purged of air, and provide quite predictable flow rates, while
containing such a small internal volume that no additional liquid
need be added to the syringe to compensate for the liquid that is
retained in the tube after its use.
The invention also provides a fluid dispensing device
adapted Eor engaging a fluid-filled syringe to dispense fluid from
the syringe at a slow, steady rate of less than 60 cubic centi-
meters per hour, said syringe being cf the type comprising an
elongate housing including a tubular wall having an open end and
an end wall having an outlet opening at the end of the tubular
wall opposi-te its open end, and a plunger having one end portion
positioned within and sealing against the inner surface of said
tubular wall and an opposite end portion projecting Erom the open
: end of said tubular wall, with the fluid being within said tubular
~ wall between said end wall and said plunger, said device compris-
~Z~73~2
-6- 5~7-2861
ing: a hose assembly having first and second ends and comprising
a capillary tube defining a passageway between said ends, said
capillary tube having a volume of less than about 0.25 cubic
centimeter and a length of at least about 45 centimeters, and said
hose assembly further including a coupler at said first end
adapted for releasably attaching said for the capillary tubing to
the housi.ng of a said syringe with the outlet opening of the
syringe communicating with said passageway; a frame comprising
support means adapted for engaging and supporting said coupler;
spring means adapted for applying a uniform force against the
plunger of the syringe to cause fluid within said syringe to flow
through said hose assembly; and activating means for moving said
spring means between a disengaged position spaced from the plunger
of a said syringe attached to said coupler to afford insertion or
removal of the syringe and said hose assembly, and an engaged
position engaged with said plunger to apply said uniform force,
said activating means including securing means ~or securing the
syringe and the coupler of said hose assembly in said support
means when said activating means positions said spring means in
said engaged position.
Brief Description of the Drawing
The device will ~urther be described with reference to
the accompanying drawings wherein like numerals reer to like parts
through the several views and wherein:
Figure 1 is a horizontal sectional view of a ~l~id dis-
pensing device coupled to a hose assembly according to the present
invention, which device has inserted therein a syrin~e frQm wllich
fluid is to be dispensed throuyh the hose assembly;
, ~
~L2;~
- -6a- 557-2861
Figure 2 is a sectional view taken approximately along
line 2-2 of Figure l;
Figure 3 is an enlarged sectional view taken approxi-
mately along line 3-3 of Figure 2;
Figure 4 is an enlarged end view of the fluid dispensing
device of Figure l;
Figure 5 is a sectional view taken approximately along
line 5-5 of Figure 4 except that a cover for the fluid dispensing
device is open, and the hose assembly and
~ .
~2;~3~,
-6B -
the syringe are not inserted in the device;
Figure 6 is a fragmentary sectional view of the
hose assembly of Figure 1.
Descri tion of the Preferred Embodiment
p
Referring now to the drawing, there is
illustrated a fluid dispensing device 10 adapted to apply a
uniform pressure to a liquid to dispense the liquid through
a hose assembly 120 according to the present invention.
The fluid dispensing device 10 is adapted to
dispense fluid at a slow, steady rate through the hose
assembly 120 over a prolonged period of time from a
conventional syringe 12 of the type including an elongate
housing 14 with an outlet tube 16 at one end, and a plunger
18 adapted to expel fluid within the syringe 12 through the
outlet tube 16.
Generally the device 10 can be used with one of
several embodiments of hose assembies, including any of the
hose assembly embodiments described in U.S. Patent No.
4,430,079 and the hose
assembly 120 described herein. Like those other hose
assemblies, the hose assembly 120 (see Figure 6) has first
and second ends 121 and 122, a coupler 125 at its first end
121 for coupling the hose assembly 120 to the syringe 12,
and a length of capillary tubing 123 shown coupled to a
needle 23 via a Luer-lock fitting 127 at its second end 122
opposite the coupler 121 to facilitate injecting the fluid
into a patient's veins or tissues. Alternatively the
tubing 123 could be open-ended to facilitate in~ertion of
the tubing 123 into a patient's digestive or breathing
passages or have attached thereto any shape of head ~ia the
Luer-lock fitting 127 or otherwi~e to facilitate
distributing fluids to a patient's body. The device 10
includes a support frame 24 comprising spaced fork-like
members 26 and 2~ for supporting the coupler 121 and the
syringe 12; and spring means 30 for applying uni~orm force
agains~ the plunger 18 of the syringe 12 to pre~s it
:
~ ~?~
--7--
towards the fork-like members 26 and 2~ and cause fluid
within the syringe 12 to flow through the hose assembly
120.
The syringe 12 which the dispensing device 10 is
adapted to receive is of a conventional type comprising the
housing 14 which includes a tubular wall 34 having an open
end 35, and an end wall 36 at its end opposite the open end
35 from which projects the outlet tube 16 which defines an
outlet opening for the housing 14, and the plunger 18 which
has one end portion positioned within and sealing against
the inner surface of the tubular wall 34 and an opposite
end portion projecting from the open end 35 of the tubular
wall 34, and which can have fluid (typically a liquid)
within the tubular wall 3~ between the end wall 36 and the
plunger 18.
~ he hose assembly 120 used and included in the
dispensing device 10 is best seen in Figure 6. Generally,
the hose assembly 120, the passageway between the ends 121
and 122 of the hose assembly 120 defined by a capillary
tube 123 h~s an volume of less than about 0.25 cubic
centimeter and a length of at least 45 centimeters, and
perferably in the range of 120 to 170 centimeters and has
the coupler 12S at its first end 121. The coupler 125 is
adapted for releasably attaching the hose assembly 120 to
the housing of the syringe 12 with the outlet opening of
the syringe communicating with the passageway through the
hose assembly 120 and has an outer periphery shaped so that
the coupler 125 will be received in the spaced for~-like
members 26 and 28 of the suppo~t frame 24 for the device 10
and will be locked in the fork-like member 26 and 28 when a
cover 35 for the device 10 is closed. Both ends of the
capillary tube 123 pass into and are bonded within bores of
the fitting 127 and the coupler 125 to secure the ends of
the capillary tube 123 thereto.
Purging of such a hose assembly 120 in the manner
described above proceeds quite rapidly because of the
relatively small amount o~ air th~t must be displaced.
~Z~7~9~
--8--
The dev.ice 10 includes activating means manually
operated by movement of the cover 53 and coupled to the
spring means 30 for allowing the syringe 12 and attached
hose assembly 120 to be easily inserted in or removed from
the device 10 by moving the spring means 30 to a disengaged
S position relative to the syringe 12 when the cover 53 is
opened, and by moving the spring means 30 to an engaged
position against the plunger 18 of the syringe 12 when the
cover 53 is closed, and means for securing the syringe 12
and hose assembly in the device 10 when the cover 53 is
closed so that they may not be tampered with when the
spring means is applying a uniform force to expel fluid
from the syringe 12.
The frame 24 includes an elongate bar-like base
portion 55 at one end of which is fixed a support member 56
including the spaced fork-like members 26 and 28 which are
disposed so that they will position the syringe 12 attached
to the coupler 125 received in the fork-like members 26 and
28 over and parallel to the base portion 55. The bar-like
baqe portion 55 has upstanding opposed generally L-shaped
rails 58 along its edges between which a hollow block 60 is
mounted for movement longitudinally of the base portion 55
via four rollers 62 projecting from the edges of the block
60 adjacent the base portion 55. A plate-like slide 64 is
also mounted between the rails 58 for sliding movement
longitudinally of the base portion 55 between the block 60
and the member 56~ A spring 66 of the type having the
~ registered tradename "Neg'ator" has a portion 68 coiled
; about a hub 69 rotatably mounted within the block 60 on a
shaft 70, and a straight end portion 71 extending from the
block 60 to the slide 64 where it is attached by a rivet
72. The "Neg'ator" spring 66 provides a constant force
attempting to wrap the entire length of the spring 66 onto
its coiled portion 68, and thus provides a constant force
biasing the block 60 toward the slide 64.
The cover 53 is a rectangular box-like member o~
rigid transparent plastic material (preferably
' .,,:'
~2~3~
g
polysulfone) having an open side disposed adjacent the
base portion 55 and having opposite outwardly projecting
trunnions 74 on its end opposite the support member 56
which are pivotably mounted between the rails 58 and two
pins 76 spaced along each of the rails 58 to afford
pivotal movement of the cover 53 from an open position
spaced from the base member 55, block 60 and syringe 12
(Figure 5); and a closed position adjacent the base member
55 enclosing the block 60 and the syringe 12 therebetween,
and with an edge portion 78 of the cover 53 against the
coupler 125 received in the fork-like members 26 and 28 to
preclude their removal (Figure 2), at which closed position
the cover 53 will ke retained by releasable latch means
later to be explained. Parallel links 80 are pivotably
mounted at their ends between the cover 53 and the slide
64, and are sized and disposed so that moving the cover 53
to its open position (Figure 5) will move the slide 64 and
block 60 to a position sufficiently spaced from the
fork-like members 26 and 28 that the metering assembly ~0
and attached syringe 12 may be inserted in or removed
therefrom; and that moving the cover 53 to its closed
position (Figure 2) will move the slide 64 adjacent the
support member 56 so that when the syringe 12 and attached
coupler 125 are supported from the fork-like members 26 and
28, the block 60 will engage the plunger 18 on the syringe
12 during such movement with the end of the plunger
received in a centering pocket 81 in the adjacent face of
the block 60. Such engagement will cause the slide 64 to
separate from the block 60 in opposition to the spring 66
so that while the cover 53 is closed, the spring 66 will
apply a constant ~orce against the plunger 18. Also while
the cover 53 is closed, the edge portion 78 rests
transversely against the co~pler 125 and precludes its
removal from between the fork-like members 26 and 28.
The means for releasably latching the cover 53
in its closed position comprises transverse matinq
hook-like lips 8~ and 86, one of which lips 8~ is a part
~Z7~2
--10--
o-f the cover 53 adjacent its edge portion 78, and the
other of which lips is a part of the fork-like member 26
adjacent its distal end; the spring 66; and a spacing
between the pins 76 that allows limited longitudinal
rnovement of the cover 53 relative to the base portion 55
of the frame 24. When the cover 53 is being moved to its
closed position and after the block 60 engages the plunger
18 of the syringe 12, the force applied by the spring 66
between the separated block 60 and slide 64 via the links
80 will press the trunnions 74 on the cover 53 against the
pins 76 oppposite the support member 56. As the cover 53
approaches its closed position, cam surfaces on the lips
84 and ~6 engage to move the center portion of the cover
53 toward the support member 56 and allow the hook-like
lips 84 and 86 to pass each other, whereupon the spring 66
again moves the center portion of the cover 53 away from
the support member 56 to engage the lips 84 and 86 as the
cover 53 reaches its fully closed position. Opening the
cover 53 then requires sliding it longitudinally toward
the support member 56 against the bias o~ the spring 66 to
disengage the lips 84 and 86 before the cover can be
pivoted to its open position, which opening operation is
not apparent from a casual inspection of the closed cover
53 and could deter unauthori~ed deactivation o~ the device
10. Alternately the means for latching the cover 53 in its
closed position could be a more conventional self-latching
push button release latch between the cover 53 and base
portion 55.
~s an example of the use of the fluid dispensing
device 10, a person first fills the syringe 12 with a fluid
to be dispensed. Next he attaches the hose assembly 120 to
the syringe 12, and manually activates the syringe 12 so
that fluid ~lows rapidly through the hose assembly and
purges air from it. Next the user presses the coupler 125
between the fork-like member~ 26 and 28 with the ~yringe 12
projecting over the base portion S5. The user then couples
the part of the ~itting 12~ on the hose assembly 120 with
.,
~ Z~3~
the part on the needle 23 or a cannula (not shown) which he
has previously inserted in a patient's vein or tissues, and
moves the cover 53 toward its closed position so that the
cover 53 via the links 80, slide 64, and spring 66 moves
the block 60 into engagement with the plunger 18 on the
syringe 12, after which the slide 64 is separated from the
block 60 so that the spring 66 will apply a force against
the plunger 18. Further movement of the cover 53 to its
closed position will cause the lips 84 and 86 on the cover
53 and fork-like members 26 to cam past each other
whereupon the spring 66 will maintain the lips 84 and 86 in
engagement to latch the cover 53 closed. In this condi-
tion, the "Neg'ator" spring 66 will continue to apply a
uniform force to cause fluid to flow at a slow uniform rate
from the syringe 12 through the hose assembly 120 and
needle 23 or cannula into the patient. During this time
the device 10 can be positioned in any attitude or carried
on the patient to afford ambulation without affecting the
fluid dispensing rate. Also tampering with the syringe 12
or hose assembly 120 while the fluid is being dispensed is
precluded since the syringe 12 is enclosed by the cover 53,
and the coupler 125 is locked between the fork-like members
26 and 2~ by the edge portion 78 of the cover, and anyone
attempting to gain access to the syringe 12 or to remove
the coupler 125 will have to open the cover 53, thereby
deactivating the device 10.
The present invention and its use have been
explained with respect to one general type of medical use.
The device may, however, be used in ways other than that
indicated both for medical or other uses. For example, one
or more of the devices 10 may be used to dispense fluids
into a standard intravenous administration set. Also, the
fluid dispensing device 10 may be used in industrial
application3 such as to introduce chemicals such as a
catalyst into fluids moving through a continuou~ proce6s,
or for othe~ uses where a s~all continuous supply of fluids
is needed. Thus the scope of the invention should not be
-12- ~2~73~
limited by either the structure or use of the embodiment
described herein, but should be determined only by the
scope of the dependent claims.
