U.S. patent application number 12/051717 was filed with the patent office on 2008-12-25 for multi-chamber syringe having a gas separator.
Invention is credited to Michael Wallace Howlett, James Victor Mercer, Bradley Carling Robinson, Nestor Rodriguez San Juan, Gale H. Thorne, Gale H. Thorne, JR..
Application Number | 20080319400 12/051717 |
Document ID | / |
Family ID | 35188043 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080319400 |
Kind Code |
A1 |
Thorne, JR.; Gale H. ; et
al. |
December 25, 2008 |
Multi-Chamber Syringe Having a Gas Separator
Abstract
A syringe is partitioned into at least proximal and distal
chambers to provide a multi-chamber, sequentially dispensing
syringe apparatus. The syringe includes a gas separator that
prevents gas from exiting a chamber with delivered fluid.
Inventors: |
Thorne, JR.; Gale H.;
(Bountiful, UT) ; Thorne; Gale H.; (Bountiful,
UT) ; Robinson; Bradley Carling; (North Salt Lake,
UT) ; Howlett; Michael Wallace; (Salt Lake City,
UT) ; Mercer; James Victor; (West Jordan, UT)
; San Juan; Nestor Rodriguez; (Hamburg, NJ) |
Correspondence
Address: |
HOLLAND & HART LLP
SUITE 2000, 60 E. SOUTH TEMPLE
SALT LAKE CITY
UT
84111-1031
US
|
Family ID: |
35188043 |
Appl. No.: |
12/051717 |
Filed: |
March 19, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11446779 |
Jun 5, 2006 |
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12051717 |
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11359304 |
Feb 21, 2006 |
7101354 |
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11446779 |
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11284504 |
Nov 22, 2005 |
7048720 |
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11359304 |
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10838101 |
May 3, 2004 |
6997910 |
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11284504 |
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Current U.S.
Class: |
604/191 |
Current CPC
Class: |
A61M 2005/3128 20130101;
A61M 5/285 20130101; A61M 5/284 20130101; A61M 5/31596 20130101;
A61M 5/286 20130101; A61M 2005/1787 20130101 |
Class at
Publication: |
604/191 |
International
Class: |
A61M 5/19 20060101
A61M005/19 |
Claims
1. A multi-chamber syringe apparatus for sequentially dispensing
medical fluids, said apparatus comprising: a syringe barrel which
is concentrically disposed about an elongated medial axis, said
barrel comprising an open proximal end and a distal end having a
closed interior surface about an orifice through which fluid is
transferred, said surface having a substantially concave shape; a
plunger and plunger stopper combination disposed to be displaced
within said barrel for dislocating fluid thereby; and a valve
assembly disposed within said barrel between said plunger stopper
and said distal end to provide a proximal chamber between the valve
assembly and plunger stopper and a distal chamber between the valve
assembly and said interior surface; said valve assembly comprising:
a valved stopper comprising a distal face and a hollow, grooved,
cylindrical interior which opens proximally toward said plunger
stopper and which communicates with said plunger stopper via fluid
within the barrel, therebetween, to be displaced as the plunger
stopper is displaced; said valved stopper further comprising an
operable, normally closed valve, which permits displacement of
fluid therethrough only when open, and a pliable material whereby
said distal face cooperatively conforms to the shape of the
interior surface when forced thereupon; and a valve actuator
comprising features which are complimentary to grooves of the
interior of the valved stopper whereby the actuator is securely
affixed to the valved stopper and is displaced as the valved
stopper is displaced; said actuator further comprising structure
for sensing impact between said distal face and said interior
surface and, upon sensing the impact, reactively causes said valve
to open.
2. Apparatus according to claim 1 wherein said actuator comprises a
medially disposed elongated body which comprises a hollow opening
which communicates with said valve.
3. Apparatus according to claim 2 wherein said actuator comprises
at least one stabilizing element, affixed to said body which acts
upon the valved stopper to resist canting of the valved stopper
within the barrel to thereby assure stability of the valved stopper
during forcible displacement by the plunger and plunger stopper
combination.
4. Apparatus according to claim 3 wherein said at least one
stabilizing element comprises a circular disk sized and shaped to
provide support within the hollow of the valved stopper.
5. Apparatus according to claim 2 wherein said valve comprises a
slit disposed through the distal face of said valved stopper.
6. Apparatus according to claim 5 wherein said stopper comprises a
size and shape relative to said hollow syringe barrel which
maintains said slit in a normally closed state unless acted upon by
a valve opening mechanism of said impact sensing structure.
7. Apparatus according to claim 5 wherein said impact sensing
structure comprises an arm which comprises a hinged connection to
said body, said arm having a distally extending appendage which
communicates with said inner surface through said distal face upon
impact between the distal face and inner surface articulates to
open said slit.
8. Apparatus according to claim 7 wherein said arm further
comprises an outwardly extending part which is in contact with the
hollow cylindrical interior of said stopper and which articulates
as said arm articulates.
9. Apparatus according to claim 8 wherein said arm and said part
couple comprise sufficient length away from said hinged connection
to compressively act to forcibly maintain said slit closed prior to
impact between said closed face and the inner surface.
10. A multi-chamber syringe apparatus for sequentially dispensing
medical fluids, said apparatus comprising: a syringe barrel having
an internal surface which is concentrically disposed about an
elongated medial axis, said barrel surface comprising an open
proximal end and a distal end having a closed interior about an
orifice through which fluid is transferred; a stem and plunger
combination disposed to be displaced within said barrel by
application of a directional force against said stem for
dislocating fluid thereby; and a valve assembly which, when
disposed within said barrel between said plunger stopper and said
distal end, provides a proximal chamber between the valve assembly
and plunger stopper and a distal chamber between the valve assembly
and said closed interior surface; said valve assembly comprising: a
valved stopper comprising a normally closed, medially disposed
valve in a distal face of the stopper and a hollow, grooved,
cylindrical interior which opens proximally toward said plunger and
which communicates with said plunger stopper via fluid, within the
barrel, said valved stopper being distally displaced toward said
distal end within said barrel when acted upon by a force
directionally applied toward said distal end which produces a first
differential pressure and being proximally displaced away from said
distal end when acted upon by an oppositely directed force of a
second differential pressure; and said valved stopper further
comprising structure which only opens said valve to permit fluid
flow there through when said stopper is acted upon by force of a
third differential pressure which is in the same direction as force
from the first differential pressure, the magnitude of the third
differential pressure being greater than the first differential
pressure.
11. A multi-chamber syringe apparatus according to claim 10 wherein
said valved stopper comprises a bi-stable valve.
12. A multi-chamber syringe apparatus according to claim 10
comprises a slit valve comprising a medially disposed slit
valve.
13. A multi-chamber syringe apparatus according to claim 12 wherein
said bi-stable valve comprises a non-planar structure.
14. A multi-chamber syringe apparatus according to claim 13 wherein
said non-planar valve comprises structure which defines operation
of said valve to be bi-stable such that, once opened, said valve
remains open.
15. A multi-chamber syringe apparatus according to claim 14 wherein
said valved stopper further comprises a hinge disposed about said
valve structure which articulates about said valve structure to
permit the valve to be displaced to an open state when acted upon
by force of said third differential pressure and to retain the
valve in the open state, once opened.
16. A multi-chamber syringe apparatus according to claim 14 wherein
said non-planar valve structure comprises a hemispherical dome
shape.
17. A multi-chamber syringe apparatus according to claim 16 wherein
said valved stopper further comprises a proximally disposed annular
groove disposed to communicate through a wide proximal opening.
18. A multi-chamber syringe apparatus according to claim 10 wherein
said valved stopper comprises material from which a syringe stopper
is made.
19. A multi-chamber syringe apparatus according to claim 10 wherein
the stem and plunger combination includes a catch that inhibits the
plunger from contacting the valve assembly.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 11/446,779, entitled "Safety Dispensing System
for Hazardous Substances," filed on 5 Jun. 2006, published on 5
Oct. 2006 as U.S. Patent Application Publication No. 2006/0224105,
which is a continuation-in-part of U.S. patent application Ser. No.
11/359,304, entitled "Mixing Syringe With and Without Flush," filed
on 21 Feb. 2006, issued 5 Sep. 2006 as U.S. Pat. No. 7,101,354,
which is a continuation-in-part of U.S. patent application Ser. No.
11/284,504, entitled "Multi-Chamber, Sequential Dose Dispensing
Syringe," filed on 22 Nov. 2005, issued on 23 May 2006 as U.S. Pat.
No. 7,048,720, which is a continuation-in-part of U.S. patent
application Ser. No. 10/838,101, entitled "Multi-Chamber Sequential
Dose Dispensing Syringe," filed on 3 May 2004, issued on 14 Feb.
2006 as U.S. Pat. No. 6,997,910 (referred to herein as "Howlett"),
each of which is incorporated by reference herein in its
entirety.
FIELD OF THE INVENTION
[0002] This invention relates to multi-chamber syringes and, in
particular, to syringes which dispense fluid from each chamber
sequentially.
BACKGROUND
[0003] During the last forty years, parenteral drug delivery has
become increasingly common and sophisticated. It is currently
estimated that nearly 90% of hospital patients receive IV
medications, often through a variety of apparatus, including
expensive electronic IV pumps and multi-channel infusion systems.
Home care patients may receive antibiotics through an elastomeric
"ball" pump. Syringe pumps are common in many hospital and
alternate site settings and are often used as a low cost
alternative to more expensive IV pumps.
[0004] Virtually all IV medications, administered through a
catheter or IV tubing, should be flushed into the vascular system
with saline or a similar physiologically compatible flushing fluid.
Such flushing assures that a patient receives a full dose of
medication, some of which otherwise might remain in the associated
IV tubing or catheter. Flushing also assures that a subsequently
infused incompatible medication does not come in contact with a
previous one. It is well known in the infusion art that flush
solutions are also used to keep an infusion line patent or
open.
[0005] With rising healthcare costs, and an ever increasing
shortage of nurses and pharmacists, there is a strong motivation to
streamline basic procedures, such as IV catheter flushing to save
clinician time. Noting that flushing usually necessitates use of a
second flushing syringe (which is often currently factory
pre-filled), the flushing syringe represents added cost, not only
in clinician time, but in terms of required additional syringes.
Use of multiple syringes also increases risk of medication error
(incorrect selection of flushing liquid) and introduction of
microorganisms (a function of number of IV line or catheter
accesses).
[0006] As an example, it is currently estimated that there are over
500 million antibiotic and chemotherapy medications administered
annually in the United States. Each of these administrations are
taught to require a follow-on flush, currently necessitating use of
a second syringe in most cases. Combining antibiotic or
chemotherapy and flush medications in one multi-chamber, sequential
dose syringe promises to save over 500 million syringes, yearly in
the United States alone, plus that additional time required for two
syringe delivery.
[0007] Multi-chamber syringes in various forms are well known.
Commonly, multi-chamber syringes are offered for use as mixing
syringes and for sequential delivery of disparate fluids,
maintaining the fluids as disparate entities until delivered.
Mixing syringes most often provide features for mixing contents of
the chambers and for delivering the mixed fluids simultaneously.
Though this invention may utilize a mixing syringe within one or
more chambers, the invention, itself, is independent of methods of
mixing which may be utilized in mixing syringes.
[0008] Generally, within each serial delivery syringe, chambers are
separated by an intermediate sliding stopper which receives motive
force communicated through an intermediate fluid from a primary
stopper which is part of a plunger assembly against which an
external force is applied. For disparate fluids to be dispensed
sequentially or serially, each intermediate stopper should provide
a fluid-tight seal until all fluid from a distal chamber is
evacuated from the syringe. Once the distal chamber of the syringe
is so purged, that intermediate stopper must be breached or
bypassed to permit dispensing of the contents of a proximal or
intermediate chamber.
[0009] An example of a multi-chamber syringe is provided in U.S.
Pat. No. 4,929,230 titled "Syringe Construction" and issued May 29,
1990 to Frederick W. Pfleger (Pfleger). Pfleger teaches a
distortable piston which is used as the intermediate stopper. The
piston of Pfleger collapses upon contact with a distal end of a
syringe to provide a fluid pathway to dispense contents from the
intermediate chamber.
[0010] While a syringe made, as an example, according to Pfleger
appears to provide a solution for sequentially dispensing disparate
fluids, there are a series of concerns which would necessarily be
associated with using such a syringe to dispense sequential doses
of medications. A first concern arises, for example, when it is
recognized that such a syringe may be used to dispense an
accurately measured dose of a very expensive medication into an IV
apparatus from a distal chamber of a multi-chamber syringe. Then,
immediately following dispensing the first medication, a volume of
a following solution is dispensed through the IV line to fully
flush the first solution.
[0011] Clearly, a deformable piston, having a hollow portion, such
as the stopper of Pfleger would not have zero dead space. Also, it
is well known that filling procedures for contents of the proximal
chamber may permit a quantity of air (or other gas) to be trapped
therein. It may be noted that even if such gas is not trapped
during filling, free gas may be found in the proximal chamber
simply as a result of out-gassing. Pfleger does not teach a way of
purging the proximal chamber of gas or of containing any gas in the
proximal chamber while only dispensing liquid therefrom, making
such a system unacceptable for use in directly administering
intravenous liquid medications to a patient. While other art may
provide more effective ways to deal with the dead space issue,
there is no known art which teaches a way of delivering only liquid
from the proximal or intermediate chambers. That such may be a
problem is recognized by U.S. Pat. No. 5,236,420 titled BYPASS,
PRESSURIZED PISTON FOR CHAMBERS issued Aug. 17, 1993, also to
Frederick W. Pfleger, discloses a valved plunger which may be used
to evacuate gas from a proximal syringe chamber.
[0012] Other art, such as U.S. Pat. No. 6,027,481 issued Feb. 22,
2000 to Laurent Barrelle, et al. (Barrelle) and U.S. Pat. No.
5,851,200 issued Dec. 22, 1998 to Tetsure Higashikawa, et al.
(Hagashikawa) disclose multi-chamber syringes with sliding valves.
However, in each case, Barrelle and Higashikawa teach special
structure requirements imposed upon a syringe barrel (a channel in
the case of Barrelle and a bulge in the case of Higashikawa) which
is used to provide a fluid pathway about a stopper.
[0013] Another U.S. Pat. No. 6,723,074 B1, titled Sequential
Delivery Syringe and issued Apr. 20, 2004 to Thor R. Halseth
(Halseth) teaches a sequential delivery syringe which utilizes a
modification to a discharge opening of a syringe for providing
access to a rear chamber of a two chamber syringe. The modification
comprises disposing a piercing member at the discharge opening. The
piercing member punctures a "mid-piston" and a collapsible bag
disposed in a rear chamber to provide access to fluid in the bag.
Access occurs when the mid-piston is displaced by action of a
plunger and stopper piston to cause the mid-piston and bag to
contact the piercing member.
[0014] Definition of Terms
[0015] Following is a brief list of clarifying definitions for the
terms used herein:
[0016] Assembly n: a device which is made from at least two
interconnected parts
[0017] Barrel n: a cylindrical elongated portion of a syringe which
is conventionally open on one end to receive a plunger and stem
used for displacing fluid within the barrel and partially closed at
an opposite end except for an orifice through which fluid is
ejected or aspirated
[0018] Bi-stable adj: a descriptor for a device having two stable
states
[0019] Clinch n: a structure or device which acts upon a part to
clamp it closed while in contact therewith
[0020] Conventional adj: a sanctioned by general custom; i.e.
commonplace, ordinary
[0021] Chamber n: a volumetric portion of a divided barrel
[0022] Disparate n: when used in conjunction with a liquid volume,
a volume of liquid which is distinctly separate from another liquid
volume
[0023] Differential pressure (.DELTA.P) n: a pressure gradient
resulting from unequal pressures exerted upon opposing sides of a
structure; generally as used herein, .DELTA.P=P.sub.p-P.sub.d
[0024] Distal adj: a term which depicts placement away from a
reference point (e.g. away from a user of a syringe)
[0025] Dome n: an arcuately shaped surface (e.g. a hemisphere)
[0026] Downstream adj: a direction which is consistent with flow
out of a syringe or away from a user
[0027] Fluid n: a substance (e.g. a liquid or gas) which tends to
take the shape of a container
[0028] Front adj/n: distally disposed or a distally disposed site
(e.g. a front of a syringe comprises the barrel orifice)
[0029] Gas n: a fluid which is neither solid nor liquid
[0030] Gas separator n: a liquid filter which inhibits gas flowing
there through
[0031] Liquid n: a fluid which is neither solid nor gaseous, free
flowing like water
[0032] Non-planar adj: not planar in a resting or stable state
[0033] Medial adj: occurring away from an outer edge; disposed near
the center of (e.g. disposed away from an edge or periphery and in
the vicinity of a center of gravity or axis of symmetry)
[0034] P.sub.d n: pressure in a distal chamber
[0035] Plunger n: a portion of a syringe piston apparatus usually
affixed to a syringe stem which is used to displace fluid within a
syringe barrel
[0036] Prime v: to fill liquid into a cavity generally by removing
air therefrom (e.g. priming a gas separator)
[0037] P.sub.p n: pressure in a proximal chamber
[0038] Proximal adj: opposite of distal (e.g. a term which depicts
placement nearer than a reference point)
[0039] Rear adj: opposite from front (i.e. generally associated
with a part of a syringe barrel which is proximal to a syringe
user)
[0040] Reflux n: a type of undesired retrograde (upstream) flow of
liquid (e.g. blood) into a catheter or the like from a vessel in
which the catheter or the like resides
[0041] Separator n: a liquid filter which impedes passage of air as
liquid flows through the separator
[0042] Stiction n: a special case of friction; stiction being the
force required to initiate motion to a resting body, esp. when
stiction is greater than moving friction
[0043] Stem n: an elongated part which fits within a syringe barrel
and is affixed to a plunger for the purpose of displacing fluid
within the barrel
[0044] Stop n: a obstruction which is differentiated from friction
or stiction which halts displacement of a stopper or plunger
[0045] Stopper n: a plunger associated with a stopper assembly, in
the instant invention, the stopper contains a self-actuating
bi-stable valve
[0046] Syringe n: a device used for injecting or withdrawing
fluids
[0047] Upstream adj: a direction which is against the direction of
flow from a syringe (opposite of downstream)
SUMMARY
[0048] In brief summary, the currently preferred embodiment of this
novel invention alleviates all known problems related to providing
an effective multi-chamber, sequential dose dispensing syringe.
Inherently, the invention involves a stopper assembly which is
disposed to operate within a conventional, substantially constant
diameter syringe barrel to separate a distal chamber from a
proximal chamber. Before dispensing, the distal chamber generally
contains a first volume of liquid. The proximal chamber contains a
disparate second volume of fluid. A closed valve in the stopper
assembly keeps the contents of each chamber separate from the
other.
[0049] In this currently preferred embodiment, the stopper assembly
comprises two elements, a valved stopper and a stopper stabilizer
and gas separator (referenced hereafter as a "separator"). The
valved stopper contains a valve mechanism which is only actuated to
open after the stopper is displaced to collide with an associated
distal end of the syringe (or another stop within the syringe) in
which the stopper assembly is disposed. This embodiment, though
novel on its own, is related to the invention disclosed in Howlett,
the U.S. patent application from which this application claims
priority.
[0050] In all embodiments of Howlett and this instant invention,
action upon a plunger associated with the syringe communicates
through the second volume of fluid to displace a stopper assembly
to the syringe end, open the valve thereby dispensing liquid from
the distal chamber. Upon complete evacuation of the liquid from the
distal chamber and by collision of the stopper assembly with the
distal internal end surface of the syringe (or another stop), a
positive differential pressure across the stopper assembly
resulting from force against the syringe stem causes the valve to
be opened. Thus, continuous action upon the stem of the syringe
permits sequential and selective dispensing of liquid contents from
the proximal chamber following dispensing of fluid from the distal
chamber.
[0051] In a preferred embodiment of this invention, the valve
assembly comprises a bi-stable valve structure, the valve itself
being characterized as a slit valve. It should be noted that a
stopper assembly according to this instant invention operates in an
unmodified standard or conventional syringe barrel, requiring no
unconventional barrel features. Examples of some previously cited
special features which may be placed in modified syringe barrels
are found in Barelle and Hagashikawa. Note that bi-stable action of
the valve provides for syringe operation only after valve opening
which mimics in all ways operation of a conventional syringe. Also,
with the valve remaining in an open state after pressure is removed
from the proximal chamber, any residual pressure associated with
stored energy within the proximal chamber acts against reflexive
flow to thereby oppose reflux in an attached catheter or other
dispensing tube.
[0052] Selective opening of the valve is based upon a common
geometry of most, currently commercially available conventional
syringe barrels. All such syringe barrels have a substantially
constant diameter hollow barrel abruptly closed at a distally
disposed inner surface. Distally, the inner surface commonly
comprises a centrally disposed orifice through which fluid is
dispensed from the barrel. Generally, a plunger, with an associated
stopper affixed thereto, is provided for forced displacement of
fluid through the barrel and orifice.
[0053] To prevent premature mixing of the disparate solutions in
syringe chambers, the stopper assembly valve should open only upon
being displaced to its most distal site in contact with the distal
end of the syringe barrel (a stop). For this reason, the stopper
assembly comprises a structure which is affected by collision
between a surface at that distal site (the stop) and, then, reacts
to open the valve when additional pressure is forced upon the
valve. In addition, to assure that the valve remains absolutely
closed until fluid is dispensed from the distal chamber, the
separator is preferably disposed and structured to act as a clinch,
applying a closing, supporting force upon the valve until the valve
is displaced from the clinch by a downstream-directed positive
differential force across the valve.
[0054] To assure effective clinching support by the separator prior
to opening the valve, the separator should be securely connected to
the valved stopper and be displaced as the valved stopper is
displaced. As is well understood in fluid mechanics, displacement
of a substantially incompressible fluid in a proximal chamber of a
syringe barrel interposed between a combination of a proximally
disposed syringe stem and associated plunger and a distally
disposed valve assembly, results in like displacement of the valve
assembly as the stem and associated plunger are displaced. The
valved stopper and separator of the instant invention, therefore,
comprise an interlocking interface which causes the separator to be
securely affixed to the valved stopper and to be jointly displaced
as the stem stopper is displaced.
[0055] An important feature of a multi-chamber syringe is a
provision for only dispensing flow from any proximally disposed
chamber (relative an initial distal chamber) to guard against
reflux (retrograde flow) into a catheter or tube upon completion of
a given dispensing cycle or operation. For this reason, a valve
assembly should operate to impede retraction of fluid at the end of
such dispensing or at completion of a dispensing operation. When no
interlock is available from an external associated part, such as
from the separator, a valve disposed within the valved stopper
should be self actuating and, once open should either close without
drawing fluid back into the syringe or remain open to assure that
no reflux occurs. Therefore, it is preferred that a valve disposed
in the stopper assembly be bi-stable. (i.e. the valve is stable in
the closed state until forced open and be disposed to remain in a
stable open state, once opened.)
[0056] In a preferred construction, such a valve is non-planar
(e.g. the valve structure may be dome shaped). In the case of a
dome-shaped valve, care should be taken to assure that displacement
of the valve upon switching does not collide with the front inner
surface of the associated syringe to thereby make switching and
opening of the valve difficult.
[0057] Non-planar or dome valves are well known, especially for
self closing food containers. As an example, U.S. Pat. No.
5,213,236 issued May 25, 1993 to Paul E. Brown, et al. (Brown),
discloses a slit valve having a rotating hinge. However, Brown
discloses a slit valve which is opened by pressure applied to an
associated container and which is self closing when pressure is
taken from the container. By repetition, it is emphasized that, for
two very important reasons, a valve according to the instant
invention should not so close after being opened. First, such
closure would most likely cause fluid to be withdrawn from an
output flow path and, second, force of closing would act against
force being used to drive liquid from the proximal chamber, making
purging of the proximal chamber more difficult than if the valve
were bi-stable and remains in an open state.
[0058] Of course, the slit valve should only open when the valve
assembly collides with the distal inner surface of the associated
syringe or stop. In all other cases, until so opened, the valve
should remain securely closed. As a syringe operation may require
bi-directional displacement of a syringe stem and resulting
bi-directional displacement of the valve assembly, it is important
to construct the valved stopper and separator to properly provide
closure support, if needed, by the slit valve in all such modes of
displacement. For this reason, the separator, which is securely
affixed to the valved stopper and thereat disposed about the valve
slit as a clinch, preferably comprises a set of ribs which
cooperate to provide clinching support for the valve about the
slit. Thus restrained, the slit valve does not open
inappropriately, especially when the syringe stem is proximally
displaced.
[0059] As noted in the parent patent application(s), when
pre-filled doses are stored in the proximal chamber for ultimate
use, it is not uncommon for gas (most commonly air) to collect in a
non-insignificant bubble size there inside. It is not good medical
practice to dispense that gas into a patient line (e.g. an IV
line). To preclude such an occurrence, the valve assembly comprises
a liquid filter which is interposed across fluid flow through the
valve to act as a gas separator. The gas separator is formed in a
centrally disposed portion of a a separator body which may be made
as a hollow frustoconical shape, being open at the bottom. A series
of small, closely spaced holes are dispersed about the conical
sides of the separator body. The top (proximal face) of the
frustoconical or thimble shaped body is closed except for at least
one hole which provides a sufficiently large exit to permit purging
of gas from the separator and delivery of at least part of the
liquid from the proximal chamber therethrough. The bottom of the
separator is open and disposed distally toward the valved stopper
to contact the inner surface of the stopper about the slit. An
outwardly projecting rim about the bottom of the separator provides
an interlocking surface for a complimentary groove molded into the
valved stopper about the slit.
[0060] Also, stability of a freely displaced valve assembly within
the barrel of a syringe should be considered. The body of the
separator is provided with sufficient radially extending appendages
to inhibit valved stopper canting.
[0061] The valve assembly may be made from only two parts. The
valved stopper may be molded from flexible synthetic resinous
material, consistent with material used in plunger stoppers. The
separator may be injection molded from semi-rigid synthetic
resinous material which is non-interactive with solutions stored in
the proximal chamber. Such a material may be polypropylene and may
be the same material used in an associated syringe barrel.
[0062] A critical factor in a valve assembly used in multi-chamber
syringes is assembly cost. Such assembly should be uncomplicated
and easily automated. For this reason, structure and function of
the valved stopper and separator are sufficiently independent that
the separator can be affixed to the valved stopper in any angular
orientation relative to the plane of a slit in the valved
stopper.
[0063] In an application for a multi-chamber syringe, a very toxic
liquid (e.g. chemotherapy agents) may be stored in the distal
chamber near the distal syringe orifice. To protect against
inadvertent contact with such toxic liquid, it is preferred to
provide some kind of a buffer. A novel addition to a multi-chamber
syringe in the form of a tube set provides such a buffer. The
tubing set comprises an elongated tube having a syringe connector
(such as a luer fitting) on a proximal end and a gas separator
assembly on the distal end. The tube is mostly filled with a buffer
liquid, the liquid being separated from contents of the distal
chamber of the syringe by a trapped air bubble. The gas separator
assembly comprises a separator component to trap and filter out the
air bubble and a fitting (such as a luer fitting) for connecting to
downstream patient lines.
[0064] In summary, the valve assembly: [0065] provides a selective
partitioning between proximal and distal chambers of a
multi-chamber syringe. [0066] may be used in conventional (off the
shelf) commercial syringes having constant diameter hollow barrels.
[0067] filters gas (e.g. air) from liquid delivered from the
proximal chamber. [0068] permits the distal chamber of the syringe
to be used in the same manner as a conventional syringe prior to
dispensing fluid from the proximal chamber. [0069] in a preferred
embodiment, provides a closed, bi-stable valve which is opened only
after collision between the valve assembly and inner surface of the
distal end of the syringe and which remains in an open state once
opened. [0070] has a valved stopper/separator interface which acts
as a clinch to maintain a slit of the valved stopper closed until
opened at the distal end of the syringe. [0071] requires a
tactilely sensible force to open the valve of the valved stopper
after collision of the valve assembly with the distal end of a
syringe. [0072] does not displace fluid proximally at an end of a
proximal chamber dispensing cycle, thereby permitting the device to
operate reflux free. [0073] separates gas from liquid and only
dispenses liquid from the proximal chamber. [0074] comprises parts
which stabilize the valve assembly throughout displacement. [0075]
permits the valve to open only upon contact with a distal end of a
syringe or other stop within the barrel of the syringe
[0076] Accordingly, it is one object to provide a valve assembly
which partitions a conventional commercial syringe to make a
multi-chamber syringe.
[0077] It is another object to provide a valve assembly for a
syringe which keeps two disparate fluids apart until one of the
fluids has been dispensed from the syringe.
[0078] It is another object to provide a valve assembly which has a
low dead space for liquid dispensed from a distal chamber.
[0079] It is another object to provide a valve assembly having an
operable slit valve.
[0080] It is another object to provide a valve actuator within a
valved stopper which senses collision between a valve assembly and
an inner surface at the end of a syringe (or other stop within the
syringe barrel) and an increased pressure across the valved stopper
to force a valving slit open.
[0081] It is another object to provide a bi-stable valve as part of
the valved stopper.
[0082] It is another object to provide a valve assembly which opens
to dispense liquid from a proximal chamber only after liquid from a
distal chamber has been dispensed.
[0083] It is another object to provide a valve assembly which acts
as a liquid filter in the proximal chamber to deter gas from being
dispensed from the proximal chamber.
[0084] It is another object to provide a separator which is a
stabilizer for an associated valved stopper in a syringe
barrel.
[0085] It is an object to provide an interface between a valved
stopper and a separator such that displacement of the valved
stopper likewise displaces the separator.
[0086] It is an object to provide a multi-chamber syringe having a
front chamber which may be used in the same manner as a
conventional syringe prior to dispensing fluid from the proximal
chamber.
[0087] It is a further object to provide a multi-chamber syringe
combination which comprises the multi-chamber syringe disclosed
supra plus an attached tubing set whereby three disparate liquids
may be kept disparate and dispensed sequentially.
[0088] These and other objects and features of the present
invention will be apparent from the detailed description taken with
reference to accompanying drawings.
DRAWINGS
[0089] FIG. 1 is a perspective of an exemplary commercial syringe
with a plunger and stopper assembly disposed within the barrel of
the syringe (prior art).
[0090] FIG. 1A is a section of the syringe seen in FIG. 1 taken
along lines 1A-1A (prior art).
[0091] FIG. 2 is a section of a syringe, similar to the section
seen in FIG. 1A, but with a valve assembly, as disclosed in
Howlett, distally disposed relative to a plunger and stopper
similar to the plunger and stopper of the syringe of FIG. 1.
[0092] FIG. 2A is a magnified portion, taken along lines 2A-2A, of
the syringe seen in FIG. 2.
[0093] FIG. 3 is a perspective of the valve assembly seen in the
syringe barrel in FIG. 2.
[0094] FIG. 4 is an exploded view of the valve assembly seen in
FIG. 3 showing a valved stopper apart from a valve actuator.
[0095] FIG. 5 is a perspective of the valved stopper, seen in FIG.
4, rotated such that the distal side of a slit valve is seen.
[0096] FIG. 6 is a perspective of a valved stopper, which is
similar to the valved stopper seen in FIG. 5, but rotated such that
the proximal side of the valve is seen.
[0097] FIG. 7 is a perspective of a valved stopper of the currently
preferred embodiment disposed to present a distal face of the
valved stopper.
[0098] FIG. 8 is a perspective to the valved stopper seen in FIG.
7, the valve being rotated to present a proximal view.
[0099] FIG. 9 is a side elevation of the valved stopper seen in
FIGS. 7 and 8.
[0100] FIG. 10 is a cross-section of the valved stopper seen in
FIG. 9.
[0101] FIG. 10A is a graphical representation of critical operating
pressures related to distal displacement and opening of a valve in
a valve assembly.
[0102] FIG. 10B is a graphical representation of critical operating
pressures related to proximal displacement and opening of a valve
in a valve assembly.
[0103] FIG. 11 is a perspective of a gas separator assembly
disposed such that the rear of distal end is seen.
[0104] FIG. 12 is a rear elevation of the gas separator assembly
seen in FIG. 11.
[0105] FIG. 13 is a perspective of the gas separator assembly seen
in FIG. 11, but rotated such that the front or proximal end is
seen.
[0106] FIG. 14 is a front elevation of the gas separator assembly
seen in FIG. 13.
[0107] FIG. 15 is a section of the gas separator assembly seen in
FIG. 13, the section being taken across two medially disposed ribs
of the separator.
[0108] FIG. 16 is a side view of a portion of a syringe in which a
valve assembly, constructed from the gas separator assembly seen in
FIG. 15 and the valved stopper (in cross section) seen in FIG. 9,
is disposed.
[0109] FIG. 17 is a side view of the valve assembly seen in FIG. 16
with a valve portion of the valved stopper seen in a first
bi-stable or closed state.
[0110] FIG. 18 is a side view of the portion of the syringe and
valve assembly seen in FIG. 16, but with a valve portion of the
valved stopper seen in a second bi-stable or open state.
[0111] FIG. 19 is a side schematic view of a multi-chamber syringe
fabricated according to the instant invention disclosed wherein is
seen a valve assembly separating a filled proximal chamber from an
empty distal chamber.
[0112] FIG. 19A is a side schematic view of the multi-chamber
syringe seen in FIG. 19 with the valve assembly disposed in contact
with an distal inner surface of a conventional syringe.
[0113] FIG. 19B is a side schematic view of the multi-chamber
syringe seen in FIGS. 19 and 20 with liquid disposed in the distal
chamber of the syringe.
[0114] FIG. 20 is a side schematic view of the multi-chamber
syringe seen in FIG. 19B with the valve assembly disposed against
the distal inner surface of the syringe.
[0115] FIG. 20A is a side schematic view of the multi-chamber
syringe seen in FIG. 20 with a valve of the valved assembly
disposed in an open state.
[0116] FIG. 20B is a side schematic view of the multi-chamber
syringe seen in FIG. 20 with a valve of the valved assembly
disposed in an open state and liquid dispensed from the proximal
chamber.
[0117] FIG. 21 is a lateral schematic view of the syringe seen in
FIG. 20B.
[0118] FIG. 22 is a lateral schematic view of the syringe seen in
FIG. 21 with a tube attached and a drop of liquid being emitted
from a distal end of the tube.
[0119] FIG. 23 is a side schematic of a multi-chamber syringe with
an attached tubing set which contains an additional liquid chamber,
liquid in the chamber being maintained disparate from liquid in the
distal chamber by a gas bubble.
[0120] FIG. 24 is a side schematic of a multi-chamber syringe
wherein an elongated barrel of the syringe comprises two sections,
a proximal section being of larger diameter than the distal
section, and a valve assembly disposed in the distal section to
divide a proximal chamber from a distal chamber.
[0121] FIG. 24A is a side schematic of the multi-chamber syringe
seen in FIG. 24 with liquid being disposed in each chamber.
[0122] FIG. 24B is a side schematic of the multi-chamber syringe
seen in FIG. 24 with liquid having been dispensed from the distal
chamber.
[0123] FIG. 24C is side schematic of the multi-chamber syringe seen
in FIG. 24 with a valve of the valve assembly disposed in an open
state and with liquid dispensed from the proximal chamber.
[0124] FIG. 25 is a schematic showing a plurality of syringes
oriented in a plurality of multi-chamber syringes demonstrating
multi-chamber syringes made in accordance with the instant
invention may be used in any position relative to gravitational
pull.
DESCRIPTION
[0125] In this description, primes of numbers are used to represent
parts which are similar, but not identical to other parts having
the same numbers. Reference is now made to embodiments illustrated
in FIGS. 1-25 wherein like numerals are used to designate like
parts throughout. It should be noted that FIGS. 1-6 are selected
from FIGS. disclosed in Howlett and are provided herein for ease of
reference.
[0126] Prior art syringes (as exemplified by syringe 10) in FIGS. 1
and 1A, are available from a large number of commercial companies
worldwide. Such syringes typically comprise an elongated hollow
syringe barrel 20 which is open at a proximal end 22 to receive a
syringe plunger 30 and stopper 40 and closed at a distal end 42
about a fluid transmission orifice 44. Generally, barrel 20 is of
substantially constant diameter (within tolerances allowed by
manufacturing methods, such as by injection molding for barrels
made from synthetic resinous materials). Stopper 40 is compressible
and sufficiently elastic when compressed to provide an efficient
wiping action along the length of an internal cylindrical surface
46 of barrel 20.
[0127] As seen in FIG. 2, a valve assembly 50 (according to
Howlett) is inserted into barrel 20 to divide space within barrel
20 into a proximal chamber 60 and a distal chamber 70. As seen in
FIGS. 2 and 2A, each chamber, 60 and 70, may be filled with a
volume of fluid, 72 and 74, respectively. It may be noted that,
when chamber 60 is substantially filled with a volume of fluid
(which should be mostly an incompressible liquid), displacement of
stopper 40 results in substantially the same displacement of valve
assembly 50. It may also be noted that fluid 72 disposed in chamber
60 is trapped and may contain a small bubble of gas, numbered 76,
(which is likely air) associated with other liquid 78 also
contained therein. Such gas 76 may be inadvertently trapped therein
during filling or may be the result of outgassing or other gas
producing phenomena following insertion of stopper 40 into barrel
20. In any event, such gas should be seriously considered and dealt
with when such a device is used to dispense liquid to a patient to
assure gas (air) is not injected into a patient line.
[0128] As disclosed in Howlett, a valve assembly 50, apart from a
barrel 20, is seen in FIG. 3. Although more parts may be used in a
valve assembly made according to the instant invention, valve
assembly 50 comprises just two parts, a valved stopper 80 and a
valve actuator 90. Note that valved stopper 80 has a hollow
cylindrical well 92 into which valve actuator 90 is displaced for
use.
[0129] Additional details of valved stopper 80 and valve actuator
90 are seen in FIG. 4. Valved stopper 80 has an outer cylindrical
wall 94 which has a pattern of annular grooves, generally numbered
96, to facilitate sealingly wiping of inner surface 46 of barrel 20
as valve assembly 50 is displaced therealong (see FIG. 2A). Within
well 92, valved stopper 80 comprises a plurality of grooves
disposition and purpose of which are disclosed in detail in Howlett
from which this application claims priority.
[0130] As seen in FIG. 4, valve actuator 90 comprises a proximal
stabilizing disk 100, a medially disposed stabilizing plate 110, a
pair of actuator arms, 120 and 120', a medially disposed support
body 130, into which is formed a gas separator vessel 140 and an
annular connecting lip 150. Note vessel 140 is penetrated by a
plurality of holes 270'. Valve actuator 90 is displaced into well
92 as indicated by dashed lines 152 and 152'.
[0131] Distal end 154 of valve assembly 50 is seen in FIG. 5. Note,
presence of a slit 160 which is medially disposed through a distal
wall 162 of valved stopper 80. Slit 160 is formed as a closed valve
which remains fluid tight until selectively opened by the action of
arms 120 and 120' as disclosed in detail in Howlett. As arms 120
and 120' must be aligned with slit 160, special manufacturing
methods, as also disclosed in Howlett, are required. Also note, a
distal surface disposed annular ring 330 which raises that surface
to collide with the inner surface of the distal end 42 of syringe
10.
[0132] Greater detail of construction of well 92 is seen in FIG. 6.
Valved stopper 80 has a plurality of grooves and associated slots,
each of which serve a specific purpose. However, there are no
grooves for rim 172 of disk 100 and outer edges 182 and 182' of
plate 110. (See FIG. 4.) Such grooves would impede distal
displacement of valve actuator 90 within valve stopper 80. Such
distal displacement is necessary for valve action, as is disclosed
in detail in Howlett. A groove 190 (see FIG. 6) coincides with
protrusions 192 and 192' of arms 120 and 120' (see FIG. 4),
respectively. A slot 200, disposed on the inner side 202, of distal
wall 162, coincides with extremities 204 and 204' of arms 120 and
120' (again see FIG. 4). Finally, an annular slotted groove 210 is
also disposed on the inner side 202 of distal wall 162 to coincide
with annular connecting lip 150, also seen in FIG. 4.
[0133] Of significant concern in valve assembly 50 is the
requirement for a required alignment between slit 160 and arms 120
and 120'. Such an alignment requires special manufacturing methods
as disclosed in Howlett and complex part handling during assembly
of valve actuator 90 into valved stopper 80. As one skilled in
molding and part assembly arts understands, there are a number of
advantages of the presently preferred embodiment. For example, as
is disclosed in detail hereafter, the part associated with gas
separation of the currently preferred embodiment is more easily
molded, the slit is more easily made, separate from other
manufacturing procedures, in the valved stopper and the two parts
are more easily assembled because there is no specific angular
orientation of the gas separator relative to the slit.
[0134] Reference is now made to FIGS. 7-25 wherein various details
of the current preferred embodiment are seen. Initial reference is
made to FIG. 16, where a valve assembly 550 is seen disposed within
a portion 552 of a barrel 20 of a syringe 10. As seen in FIG. 16
syringe 10 ends in a surface or stop 554 having a predetermined
concave or frustoconical shape 556 and a medially disposed orifice
44 through which fluid flows (see also FIGS. 1 and 2). Note that
valve assembly 550 comprises a valved stopper 580 and a liquid
filter or gas separator, generally referenced as separator 590. As
seen in FIG. 7, valved stopper 580, comprises a distal surface 592
and an outer cylindrical wall 594. Wall 594 has a pattern of
annular grooves, generally numbered 596, to facilitate sealingly
wiping of inner surface 46 of barrel 20 as valve assembly 550 is
displaced through barrel 20 (See FIG. 16.). Distal surface 592
comprises an outer facing ring 598 and a recessed medial portion
600. Outer facing ring 598 is preferably contoured to conform to an
inner distal surface or stop 554 of distal end 42 of syringe
10.
[0135] Recessed medial portion 600 (see FIG. 7) is bounded by a
cylindrical wall 602, an annular hinge 604, peripherally affixed to
wall 602, and a medially disposed, non-planar valve 610 affixed to
an inner portion of hinge 604. On a distal surface 612, a portion
of a planar slit 620 is seen to be medially disposed in valve
610.
[0136] A Self-Actuating Valved Stopper
[0137] Valved stopper 580 is rotated in FIG. 8 to reveal a hollow
cylindrical inner core 622, a distal interior surface 624 of valve
610, a portion of annular hinge 604 which circumscribes valve 610
and an annular groove 630, the purpose for which is disclosed in
detail hereafter. Exterior shape and form of valved stopper 580 are
seen in FIG. 9. Note frustoconical shape of surface 598, which is
shaped to conform with contour of inner surface 554 of distal end
42 of syringe 10 to minimize dead space.
[0138] A cross section of valved stopper 580 is seen in FIG. 10 to
be disposed within a section 632 of a barrel 20. As such, valved
stopper 580 divides space in barrel 20 into a proximal chamber 60
and a distal chamber 70. A pressure resident in chamber 60 is
represented by P.sub.p. A pressure resident in chamber 70 is
represented by P.sub.d. If P.sub.p is not equal to P.sub.d, the
non-zero pressure gradient is represented by .DELTA.P (i.e.
.DELTA.P=P.sub.p-P.sub.d). Note, that, if .DELTA.P is positive, the
resulting motive force upon proximally facing surfaces 636 of
valved stopper urges valved stopper 580 toward end surface 554. If
.DELTA.P is negative, the resulting force upon distally facing
surfaces 638 urges valved stopper 580 away from surface 554. Thus
force upon plunger 30 of syringe 10 in a distal direction relative
to barrel 20 tends to generate a positive .DELTA.P and a force in a
proximal direction relative to barrel tends to generate a negative
.DELTA.P.
[0139] Due to the fact that stopper 580 is displaceable within
barrel 20, P.sub.p and the associated .DELTA.P is effectively
limited when .DELTA.P produces a force across surfaces 636 which
overcomes friction (and stiction) to displace stopper 580. Note
that, if a valve in Stopper 580 is also opened by a predetermined
.DELTA.P, a force which overcomes friction to displace stopper 580
must be less than the force which results in opening a valve
disposed in valve stopper 580.
[0140] As seen in FIG. 10, stopper 580 comprises a medially
disposed, dome-shaped valve 640. Valve 640 is affixed to the
remaining body 642 of stopper 580 via an annular hinge 650. It
should be noted that, while valve 640 is hemispherical in shape,
any valve shape which remains closed at a .DELTA.P which displaces
stopper 580 distally and which opens at a greater .DELTA.P may be
used within the scope of the invention. Such valves are usually
non-planar. Further, as is disclosed in detail hereafter, there are
important reasons for such a valve to remain open (be bi-stable)
once being opened.
[0141] As may be noted in FIG. 10, valve 640 has a proximal surface
660 having a radius of curvature 662, a distal surface 670 having a
radius of curvature 672 and a medially disposed slit 680. Hinge 650
has a thickened portion 682 where hinge 650 is affixed to remaining
body 642 of stopper 580 and a thinned portion 684 where hinge 650
is affixed to valve 640. Thicknesses of hinge 650 and valve 640
determine .DELTA.P necessary to open valve 640.
[0142] As an example, in a valve made to operate in a stopper for a
20 milliliter syringe, having an internal barrel diameter of
approximately 0.8 inches, a valve assembly may be manufactured
wherein the diameter of the stopper is increased to a diameter four
percent grater than the internal barrel diameter. The proximal
surface radius 662 may be approximately 0.25 inches. Thickness of
the wall between surfaces 662 and 672 would be nominally 0.040
inches, although a variance of 0.012 may be allowed. Thickness of
thickened portion 682 of annular hinge 650 was approximately 0.100
inches. Thickness of thinned portion 684 may be nominally 0.060
inches. Slit 680 is nominally approximately 0.160 inches.
[0143] Reference is now made to FIG. 10A which provides a graph o
of a positive .DELTA.P versus displacement of stopper 580 in a
barrel 20. Zero (0) marks an initial stationary point of stopper
580 relative to a point of collision (C) between stopper 580 and
surface or stop 554 (see FIG. 18). Dashed line 690 represents a
pressure differential necessary to overcome friction (and stiction)
to displace stopper 580. A second dashed line 692 represents a
.DELTA.P which forces valve 640 open. Solid line 694 is an example
of .DELTA.P as stopper 580 traverses through barrel 20. Note that
.DELTA.P 694 is substantially constant until collision between
stopper 580 and surface 554 when .DELTA.P 694 rises sharply to
opening pressure differential 692, then falls rapidly as released
flow decreases chamber 60 pressure. Note that any collision with a
stop within barrel 20 would result in such a rise in .DELTA.P.
[0144] An opened valve 640 is seen in FIG. 18. Note that, once
valve 640 is forced to an open state, surfaces 660 and 670 are
turned inside out (inverted). Surface 670, having the smaller
radius of curvature of the two surfaces, tends to open slit 680
when dome-shaped valve 640 is inverted. The combination of inherent
locking nature of the inverted surfaces and force imposed by
annular hinge 650 tends to hold valve 640 in the open state
providing a bi-stable valve which is maintained in an open state,
once opened. Such a state has a definite advantage in IV therapy
and is disclosed in detail hereafter.
[0145] An example of such a valved stopper has been made and tested
by West Pharmaceutical Services, 101 Gordon Drive, PO Box 645,
Lionville, Pa. 19341. As earlier disclosed, these valved stoppers
were made with a diameter which is approximately four percent
larger than an inner diameter of a 20 ml syringe barrel in which
they were disposed. With such a design, pressure to slide a
siliconized stopper was in the range of 2.4 to 5.6 pounds
(generally about three to four pounds). Pressures to open the
valved stoppers ranged from 12.50 to 22.2 pounds. While such
pressure ranges may vary due to size and material factors, these
pressures may be considered representative of pressure
differentials evidenced in valve actuation. Material used in
stoppers associated with these tests was West Formulation 4023/50
Gray.
[0146] A problem associated with a non-planar valve, when employing
a syringe 10 to withdraw fluids into a front chamber 70 (as is done
with a conventional syringe), is a tendency of the valve (e.g.
dome-shaped valve 640) to "balloon" when .DELTA.P is negative. Such
ballooning tends to open slit 680 to open permitting
cross-contamination of contents of chambers 60 and 70. As seen in
FIG. 10B, a negative .DELTA.P as indicated by dashed line 696 may
be commonly disposed across valve 640 (as an example to fill
chamber 70). Ballooning, opening an unclinched slit 680, may
commonly occur at a smaller negative .DELTA.P, indicated by dashed
line 698. To solve this problem a restraint should be disposed
about surface 660 in the form of a clinch to maintain slit 680
closed. For this and other purposes, a separator component
(generally referenced separator 700) having a clinch, as seen in
detail in FIGS. 11-15, is firmly affixed to stopper 580 about valve
640.
[0147] A Separator, Stabilizer and Clinch
[0148] Separator 700 is similar to actuator 90 (see FIG. 4).
However separator 700 is not required to comprise arms 120 and 120'
because stopper valve 640 is self-actuating and is inherently
bi-stable. A set of orthogonally disposed wings, generally numbered
710 (see FIGS. 13 and 14), are proximally disposed on a
frustoconically shaped body 712 of separator 700 to provide
stabilizing support when separator 700 is affixed to stopper 580
and disposed in a barrel 20. These wings 710 replace disk 100 and
plate 110 of actuator 90 (see FIG. 4). Structure of holes,
generally numbered 270' (see FIG. 15), is relatively unchanged from
actuators disclosed in Howlett, except for a plurality of holes
270'' disposed through a proximal face of separator 700 (see FIGS.
13 and 14). Holes 270' and 270'' provide a low resistance pathway
for liquid and a much higher resistance pathway for gas (air),
thereby forming an effective liquid filter, filtering gas from
dispensed liquid as do holes 270' of actuator 90.
[0149] On a distal side 714 of body 712 (see FIG. 11) separator 700
has an open throat 716. Disposed about throat 716 is a structure
which forms an annular lip 720 (see FIG. 11). Referring once more
to FIG. 10, stopper 580 is seen to have annular groove 730 disposed
about dome valve 640. Lip 720 (see FIG. 11) and groove 730 comprise
complementary shapes such that lip 720 fits into groove 730 to
securely and sealingly affix separator 700 to stopper 640 to form a
valve assembly 740 (see FIGS. 16-18).
[0150] As may be best seen in FIG. 11 body 712 comprises a
plurality of medially directed ribs, generally numbered 750. Each
distal surface 752 of each rib 750 comprises a curvature which is
similar in size and radius of curvature of exterior surface 660
(see FIG. 10). However, in combination, surfaces 752 each have a
sufficiently smaller radius of curvature 754 (see FIG. 15) than
radius of curvature 660 to act as a clinch against proximal surface
624 of domed valve 610. Thus, in combination ribs 750 form a clinch
780 (see FIG. 15) which acts to maintain slit 680 (see FIG. 10) in
a closed state when separator 700 is affixed to valved stopper 640
and a .DELTA.P across dome valve 640 is negative.
[0151] A Valve Assembly
[0152] Valve assembly 740 may be seen in various dispositions in
FIGS. 16-18 with separator 700 securely affixed to valved stopper
640. In FIG. 17, separator 700 is shown as transparent, permitting
dome valve 640 to be clearly seen. In FIG. 16, valve assembly 740
is disposed proximally apart from surface 554 such that slit 680
(see FIG. 17) remains closed keeping fluids residing in chambers 60
and 70 disparate. In FIG. 18, valve assembly 740 is disposed
against a stop provided by surface 554 with sufficient force being
exerted upon an associated plunger to create a sufficiently large
positive .DELTA.P to invert dome valve 640 and open slit 680. Note
that indentation of dome valve 640 a distance defined by the width
of wall 602 (see FIGS. 8 and 18), permits valve 640 to bulge
outward upon opening without conflicting with surface 554.
[0153] Various modes of use of valve assembly 740 in a syringe 10
are seen in FIGS. 19, 19A-B, 20 and 20A-B. As seen in FIG. 19,
valve assembly 740 is disposed to divide syringe 10 into two
disparate chambers 60 and 70. A fluid comprising mostly liquid is
disposed in chamber 60 while chamber 70 is empty. In FIG. 19A, a
plunger 30 is displaced distally to likewise displace valve
assembly 740 to empty chamber 70. Note that valve 640 (see in FIG.
17) remains closed as tactile and visual senses permit valve
assembly 740 to be displaced to completely empty chamber 70 without
activating (opening) valve 640. In FIG. 19B, plunger 30 is
displaced proximally to withdraw liquid 790 into chamber 70, just
as might be done with a conventional syringe without a valve
assembly 740.
[0154] As seen in FIG. 20, plunger 30 has been displaced to cause
valve assembly 740 to dispense liquid 790 from chamber 70 (see FIG.
19, as chamber 70 is totally evacuated in FIGS. 20 and 20A-B).
However, note that a small residual of liquid 790 still resides in
orifice 44. Flushing of such liquid 790 from orifice 44 and other
spaces within a patient delivery system is one significant reason
for using a multi-chamber syringe. Further an additional force
disposed upon plunger 30 effectuates opening of valve 640 as seen
in FIG. 20A.
[0155] Continued application of distally directed force upon
plunder 30 dispenses a large measure of the liquid content 792 of
chamber 60. Note that any gas 76 (see FIGS. 2A and 20B) which was
originally disposed in chamber 60, remains in chamber 60 and is not
dispensed but remains with an undelivered portion of liquid 792. As
seen in FIG. 25, a syringe 10 with a valve assembly 740 may be
dispensed per the arrows, generally numbered 794 seen in FIGS. 19,
19A-B, 20 and 20A-B in any orientation relative to gravitational
attraction without dispensing undesirable portions of gas 76 from
chamber 60.
[0156] Reflux-Free Operation
[0157] A magnified and rotated view of syringe 10 and contents seen
in FIG. 20B is seen in FIG. 21. It is important to note that
plunger 30 has a catch 796 which inhibits plunger 30 from
contacting valve assembly 740, thereby leaving a fluid buffer 798
disposed between plunger 30 and valve assembly 740. Due to contents
of elastic material (e.g. gas or a rubber stopper of plunger 30)
and due to valve 640 remaining in a bi-stable state whenever
plunger 30 stops, a small positive flow continues to be dispensed
from syringe 10. There is no negative flow allowed due to memory of
the elastic material. For this reason, rather than reflux flow into
a connected line 800, seen in FIG. 22, a small amount of liquid
(seen as droplet 802) continues to be dispensed each time plunger
30 stops after valve 640 is open.
[0158] A Three Chamber Multi-Chamber Syringe
[0159] On occasion it may be desirable to dispense a toxic medicine
810 from chamber 70 of a multi-chamber syringe made from a syringe
10 and valve assembly 740. In such a case, any contact through
orifice 44 could be dangerous to a clinician or care giver. In such
a situation, it would be preferable to provide an additional distal
buffering capacity to provide an increased safety factor.
[0160] A combination 820 for such a purpose is seen in FIG. 23.
Combination 820 includes a syringe 10 and a valve assembly 740
which divides barrel 20 into chambers 60 and 70. Syringe 10 is
connected to a tubing set 830 comprising an elongated tubing shown
in two parts 832 and 834 connected by a dashed line 836 for clarity
of presentation. A buffer solution 840 which is hazard free is
disposed within tubing set 830 such that any initial fluid
dispensed from combination 820 will not be dangerous. To keep
contents of chamber 60 disparate from solution 840, a gas (air)
bubble 850 is disposed in a proximal portion of tubing set 830. It
is well known in fluid processing art that such an air bubble will
keep liquid, on opposite sides of the air bubble, disparate,
thereby maintaining integrity of contents of chamber 70. Of course,
gas (air) should not be dispensed from combination 820. For this
reason an additional liquid filter 700' having similar filtering
holes as those disclosed for separator 700 is provided in a chamber
852 disposed at a distal outlet portion 854 of tubing 834. Note
also, that a preferable tubing connector 856, such as a luer
fitting, is comprised within chamber 852 distal to filter 700'. In
this manner, a multi-chamber syringe is increased in scope to a
three chamber combination, with the third chamber being provided by
tubing set 830.
[0161] A Precisely Fillable Multi-Chamber Syringe
[0162] In some applications of multi-chamber syringes, it is
desirable to accurately fill a distal chamber, such as chamber 70,
with a small volume liquid dose. Syringe barrels, such as barrel 20
may be too large to permit facilely derived, precision, small dose
measurements. For this reason, a syringe, such as syringe 10', seen
in FIGS. 24 and 24A-C, may be employed with a modified valve
assembly 740'. Syringe 10' has a contiguous barrel which is divided
into two sections, a proximal section 20' and a distal section
20''. Proximal section 20' is easily seen to be larger in diameter
than distal section 20''. Valve assembly 740' comprises two parts,
a valved stopper 640' and a separator 700''. Note that a plunger 30
with an associated stopper is disposed and displaced within
proximal section 20'. Valve assembly 740' is disposed distal
section 20''. Valve assembly divides syringe 10' into two chambers,
proximal chamber 60' and distal chamber 70'. Of course, it is
important that valve assembly 740' be perpetually retained in
section 20''.
[0163] It should be noted that, due to the relatively reduced
diameter of section 20'' relative to the diameter of section 20',
for each unit of distance plunger 30 is displaced, valve assembly
740' is displaced a greater distance. To assure that valve assembly
740' is not extricated from section 20'' by displacing plunger 30
too great a distance proximally, separator 700'' is sufficiently
elongated to contact a most distal portion of plunger 30 before
valved stopper 640' is pulled from section 20''. Because valve
assembly 740' moves farther than plunger 30 in either direction,
such contact effectively forms a lock which assures valve assembly
740' remains in section 20'' (see FIG. 20A). Separator 700''
comprises liquid filtering holes and features which affix separator
700'' to valved stopper 640' in a manner similar to holes and
features of separator 700 is affixed to valved stopper 640.
[0164] Note that a set of finely placed indicia 860 are imprinted
upon a side of section 20'' to facilitate precise measurement of
liquid withdrawn into section 20''. Dispensing of liquid from
syringe 10' using valve assembly 740' is the same as dispensing
liquid from syringe 10 using valve assembly 740. As may be noted in
FIG. 24B, plunger 30 is displaced to force valve assembly 740' to
be stopped at the distal end of syringe 10'. When thereat,
additional force opens a slit valve of valved stopper 640' and
liquid is dispensed therethrough.
[0165] This invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the scope of this
invention being indicated by the appended claims rather than by the
foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are therefore
intended to be embraced therein.
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