U.S. patent application number 10/754870 was filed with the patent office on 2005-07-14 for positive displacement flush syringe.
Invention is credited to Alheidt, Thomas Adam.
Application Number | 20050154353 10/754870 |
Document ID | / |
Family ID | 34739460 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050154353 |
Kind Code |
A1 |
Alheidt, Thomas Adam |
July 14, 2005 |
Positive displacement flush syringe
Abstract
A positive displacement flush syringe includes a barrel having a
chamber for retaining fluid and an elongate tip extending distally
therefrom having a passageway therethrough in fluid communication
with the chamber. A plunger having a stopper which is slidably
positioned in said chamber for driving fluid out of the chamber by
movement of the stopper relative to the barrel is provided.
Further, structure is provided to move fluid distally in the
passageway after fluid has been delivered from the chamber and the
stopper is in contact with the distal wall of the chamber.
Inventors: |
Alheidt, Thomas Adam; (Lake
Stockholm, NJ) |
Correspondence
Address: |
DAVID W. HIGHET, VP AND CHIEF IP COUNSEL
BECTON, DICKINSON AND COMPANY
1 BECTON DRIVE, MC 110
FRANKLIN LAKES
NJ
07417-1880
US
|
Family ID: |
34739460 |
Appl. No.: |
10/754870 |
Filed: |
January 9, 2004 |
Current U.S.
Class: |
604/218 ;
604/228 |
Current CPC
Class: |
A61M 5/31515 20130101;
A61M 5/3135 20130101; A61M 2005/1403 20130101; A61M 2005/31508
20130101; A61M 2005/3103 20130101; A61M 2005/31523 20130101; A61M
2005/31506 20130101; A61M 2005/31516 20130101 |
Class at
Publication: |
604/218 ;
604/228 |
International
Class: |
A61M 005/315 |
Claims
What is claimed is:
1. An I.V. flush syringe assembly comprising: a barrel including a
cylindrical side wall having an inside surface defining a chamber
for retaining fluid, an open proximal end and a distal end
including a distal wall with an elongate tip extending distally
therefrom having a passageway therethrough in fluid communication
with said chamber; a plunger including an elongate body portion
having a proximal end, a distal end and a resilient stopper
slidably positioned in fluid-tight engagement with said inside
surface of said barrel for drawing fluid into and driving fluid out
of said chamber by movement of said stopper relative to said
barrel, said elongate body portion extending outwardly from s aid
open proximal end of said barrel; and means for moving fluid
distally in said passageway after fluid has been delivered from
said chamber and said stopper is in contact with said distal
wall.
2. The syringe assembly of claim 1 wherein said means for moving
fluid comprises said stopper including a distal end having a distal
surface and a proximal end having a cavity therein defining an
inside surface, said distal end of said plunger connected to said
stopper by a complementary detent structure defining a first detent
position and a second detent position, said detent structure being
configured so that a distally directed force applied to said
plunger after fluid has been delivered from said chamber causes
said plunger to move distally with respect to said stopper from
said first detent position to said second detent position so that a
distal tip on said distal end of said plunger contacts said inside
surface of said stopper forcing part of said distal end of said
stopper into said passageway to move fluid distally in said
passageway.
3. The syringe assembly of claim 1 wherein said stopper includes a
conically shaped distal surface and said inside surface of said
barrel at said distal wall being conically shaped wherein said
total included angle of said inside surface of said barrel at said
distal wall is greater than said total included angle of said
stopper distal surface.
4. The syringe assembly of claim 2 further including a distally
directed projection on said distal end of said stopper shaped to
fit in said passageway when said plunger and said stopper are
engaged in said second detent position.
5. The syringe assembly of claim 2 wherein said inside surface of
said stopper includes a proximally directed protuberance configured
to contact said distal tip of said plunger when said plunger and
said stopper are engaged in said second detent position.
6. The syringe assembly of claim 2 wherein said inside surface of
said stopper includes a first discontinuity and a second
discontinuity located distally from said first discontinuity, and
said distal end of said plunger includes a discontinuity positioned
so that when said stopper and said plunger are in said first detent
position said plunger discontinuity engages said first
discontinuity and when said stopper and said plunger are in said
second detent position said plunger discontinuity engages said
second discontinuity.
7. The syringe assembly of claim 6 wherein said discontinuity on
said distal end of said plunger includes a raised projection.
8. The syringe assembly of claim 7 wherein said raised projection
is an annular ring.
9. The syringe assembly of claim 8 wherein said first discontinuity
is a recess for containing said raised projection on said distal
end of said plunger.
10. The syringe assembly of claim 9 wherein said recess is
annularly shaped.
11. The syringe assembly of claim 1 including flush solution in
said chamber.
12. The syringe assembly of claim 11 further including a tip cap
releasably connected to said tip of said syringe barrel for sealing
said passageway.
13. The syringe assembly of claim 11 wherein said flush solution is
selected from the group consisting of saline flush solution and
heparin lock flush solution.
14. The syringe assembly of claim 1 wherein said stopper is made of
material selected from the list consisting of thermoplastic
elastomers, natural rubber, synthetic rubber, thermoplastic
materials and combinations thereof.
15. The syringe assembly of claim 1 further comprising a needle
assembly including a cannula having a proximal end, a distal end
and a lumen therethrough, and a hub having an open proximal end
containing a cavity and a distal end attached to said proximal end
of said cannula so that said lumen is in fluid communication with
said cavity, said needle assembly being removably attached to said
tip of said barrel through engagement of said tip to said cavity so
that said lumen is in fluid communication with said chamber.
16. The syringe assembly of claim 2 further including a spring
between said distal tip and said distal end of said plunger, said
spring configured to compress when said plunger moves to said
second detent position with respect to said stopper.
17. The syringe assembly of claim 2 further including said barrel
and said plunger having complementary detent structures defining a
primary detent position and a secondary detent position to hold the
position of said plunger relative to said barrel, said primary
detent position being positioned to engage when fluid has been
delivered from said chamber and said stopper is in contact with
said distal wall, said secondary detent position being engaged upon
application of said distally directed force to said plunger.
18. The syringe assembly of claim 17 wherein said proximal end of
said barrel includes a first discontinuity and a second
discontinuity located distally from said first discontinuity and
said proximal end of said plunger includes a discontinuity
positioned so that when said plunger and said barrel are in said
primary detent position said proximal plunger discontinuity engages
said first barrel discontinuity and when said plunger and said
barrel are in said secondary detent position said proximal plunger
discontinuity engages said second barrel discontinuity.
19. The syringe assembly of claim 18 wherein said proximal plunger
discontinuity is an outwardly directed projection.
20. The syringe assembly of claim 19 wherein said outwardly
directed projection is an annular ring.
21. The syringe assembly of claim 19 wherein said second barrel
discontinuity is a recess for containing said proximal plunger
discontinuity.
22. The syringe assembly of claim 17 wherein said plunger includes
a radial projection positioned so that when said plunger and said
barrel are in said primary detent position said radial projection
engages said inside surface of said barrel and when said plunger
and said barrel are in said secondary detent positions, said radial
projection engages said inside surface of said barrel at a position
located distally from said primary detent position.
23. An I.V. flush syringe assembly comprising: a barrel including a
cylindrical side wall having an inside surface defining a chamber
for retaining fluid, an open proximal end and a distal end
including a distal wall with an elongate tip extending distally
therefrom having a passageway therethrough in fluid communication
with said chamber; a tip cap releasably connected to said elongate
tip for sealing said passageway; a plunger including an elongate
body portion having a proximal end, a distal end and a resilient
stopper, a quantity of flush solution in said chamber, said stopper
slidably positioned in fluid-tight engagement with said inside
surface of said barrel for drawing fluid into and driving fluid out
of said chamber by movement of said stopper relative to said
barrel, said stopper including a conically shaped distal surface
and said inside surface of said barrel at said distal wall being
conically shaped wherein said total included angle of said inside
surface of said barrel at said distal wall is greater than said
total included angle of said stopper distal surface, said elongate
body portion extending outwardly from said open proximal end of
said barrel; and means for moving fluid distally in said passageway
after fluid has been delivered from said chamber and said stopper
is in contact with said distal wall including said stopper having a
distal end having a distal surface and a proximal end having a
cavity therein defining an inside surface, said distal end of said
plunger connected to said stopper by a complementary detent
structure defining a first detent position and a second detent
position, said detent structure being configured so that an
additional distally directed force applied to said plunger after
fluid has been delivered from said chamber causes said plunger to
move distally with respect to said stopper from said first detent
position to said second detent position so that a distal tip on
said distal end of said plunger contacts said inside surface of
said stopper forcing part of said distal end of said stopper into
said passageway to move fluid distally in said passageway.
24. The syringe assembly of claim 23 further including a distally
directed projection on said distal end of said stopper shaped to
fit in said passageway when said plunger and said stopper are
engaged in said second detent position.
25. The syringe assembly of claim 23 wherein said inside surface of
said stopper includes a proximally directed protuberance configured
to contact said distal tip of said plunger when said plunger and
said stopper are engaged in said second detent position.
26. An I.V. flush syringe assembly comprising: a barrel including a
cylindrical side wall having an inside surface defining a chamber
for retaining fluid, an open proximal end and a distal end
including a distal wall with an elongate tip extending distally
therefrom having a passageway therethrough in fluid communication
with said chamber; a tip cap releasably connected to said elongate
tip for sealing said passageway; a plunger including an elongate
body portion having a proximal end, a distal end and a resilient
stopper, a quantity of flush solution in said chamber, said stopper
slidably positioned in fluid-tight engagement with said inside
surface of said barrel for drawing fluid into and driving fluid out
of said chamber by movement of said stopper relative to said
barrel, said elongate body portion extending outwardly from said
open proximal end of said barrel; and means for moving fluid
distally in said passageway after fluid has been delivered from
said chamber and said stopper is in contact with said distal wall
including said stopper having a distal end having a distal surface
and a proximal end having a cavity therein defining an inside
surface, said distal end of said plunger connected to said stopper
by a complementary detent structure defining a first detent
position and a second detent position, said detent structure being
configured so that a distally directed force applied to said
plunger after fluid has been delivered from said chamber causes
said plunger to move distally with respect to said stopper from
said first detent position to said second detent position so that a
distal tip on said distal end of said plunger contacts said inside
surface of said stopper forcing part of said distal end of said
stopper into said passageway to move fluid distally in said
passageway; a spring between said distal tip and said distal end of
said plunger, said spring configured to compress when said plunger
moves to said second detent position with respect to said stopper;
and said barrel and said plunger having complementary detent
structures defining a primary detent position and a secondary
detent position to hold the position of said plunger relative to
said barrel, -said primary detent position being positioned to
engage when fluid has been delivered from said chamber and said
stopper is in contact with said distal wall, said secondary detent
position being engaged upon application of said additional distally
directed force to said plunger.
27. The syringe assembly of claim 26 further including a distally
directed projection on said distal end of said stopper shaped to
fit in said passageway when said plunger and said stopper are
engaged in said second detent position.
28. The syringe assembly of claim 26 wherein said inside surface of
said stopper includes a proximally directed protuberance configured
to contact said distal tip of said plunger when said plunger and
said stopper are engaged in said second detent position.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to syringe assemblies and
particularly to syringe assemblies for use in flush procedures, for
vascular access devices (VAD's).
[0002] VAD's are commonly used therapeutic devices. There are two
general classifications of VAD's, peripheral catheters and central
venous catheters. If not properly maintained, VAD's can become
occluded. To ensure VAD's are used properly and do not become
occluded, standards of practice have been developed. These
standards include a cleaning procedure, which is commonly referred
to as a flush procedure or flushing a catheter.
[0003] VAD standards of practice usually recommend flush procedures
be performed after catheter placement, before fluid infusion, and
before and after drug administration, blood sampling, transfusions
and parenteral nutrition. The goal of these flush procedures is to
confirm catheter patency, avoid drug incompatibilities, ensure the
complete drug dose administration, prevent thrombus formation and
minimize the risk of blood stream infections. Flush procedures
require different types and amounts of flush solutions. The most
commonly used flush solutions are saline and or heparin lock
solution. The type of flush solution and amount vary depending on
the specific type of catheter. Flush solution volumes between 5 and
10 ml are most common but can range from 1 to 20 ml. Flush
procedures also require that care be taken to prevent blood reflux
into the catheter. Reflux in I.V. therapy is the term commonly used
to describe the fluid that is drawn back into the catheter after a
flush procedure. The concern is that the reflux fluid contains
blood or solution that could cause the catheter to occlude. To
ensure that reflux does not occur, flush procedures suggest two
techniques: 1) at the end of the flush solution delivery, the user
maintains pressure on the syringe plunger while clamping the I.V.
line; or 2) while delivering the last 0.5 ml of flush solution
disconnect the syringe from the I.V. port or clamp the I.V. line.
Either technique maintains positive pressure on the fluid in the
VAD to prevent reflux of fluid and blood.
[0004] For flush procedures, the I.V. line refers to the system
containing a VAD, tubing set with clamp and may terminate with a
port or valve. The most common types of I.V. ports are covered by
pierceable septums or pre-slit septums and are known in the art and
sometimes referred to as "PRN" from the Latin pro re nata meaning
"as the need arises". The septum is preferably made of rubber or
another elastomeric material, which permits insertion of a sharp
needle cannula in order to infuse fluids or to withdraw fluids from
the catheter. Upon withdrawal of the needle cannula the septum
seals itself. Ports having pre-slit septums are used with blunt
cannula or the frustoconically shaped tip of a syringe barrel. The
syringe tip or the blunt cannula (which is usually attached to a
syringe) is gently pushed through the pre-slit septum to establish
fluid communication.
[0005] I.V. valves, another type of terminal I.V. access device
that does not require a needle having a sharp tip, are activated by
the frustoconically shaped tip of a syringe barrel to allow fluid
communication between the interior of the syringe and the catheter.
These valves may contain structure for delivering fluid from a
storage compartment in the valve to the catheter, and are referred
to in the art as positive displacement valves. Such a valve is
taught in U.S. Pat. No. 6,206,861B1. Positive displacement valves
were developed to overcome the reflux caused by the disconnection
of a syringe tip or cannula from a port or valve. Unfortunately,
the positive displacement valves were not designed to compensate
for the worst-case syringe stopper induced reflux. When using a
traditional syringe assembly containing an elastomeric stopper, the
stopper is often compressed when it contacts the distal end of the
syringe barrel at the completion of the flush procedure. If the
user releases the pressure on the plunger after the flush solutions
is delivered, the compressed stopper may expand back to its normal
size drawing fluid back into the catheter. This fluid is referred
to as syringe stopper induced reflux. Traditional syringe
assemblies were designed to accurately deliver medications.
Traditional syringe assemblies supplied by various suppliers may
appear similar but can vary significantly in terms of performance
especially stopper induced reflux. Because the catheter is inserted
into the patient the users cannot see the reflux when it occurs and
therefore cannot take corrective actions to address a potential
problem.
[0006] Disconnection induced reflux and syringe stopper induced
reflux would not be an issue if all users practice the positive
pressure flushing techniques described hereinabove every time they
flushed a VAD. However, user experience, environmental circumstance
and patient condition vary significantly within the hospital
setting and even more when one considers other areas that flush
procedures are performed such as clinics and home care. As a
result, VAD's are frequently occluded resulting in the need for
additional professional time, declotting drugs, removal of
catheters and new procedures to place new catheters. All of these
interventions come at a cost to the healthcare system and its
patients. It is desirable to have syringe assemblies that are
designed for flush procedures to enhance best clinical practice.
Specifically, syringe assemblies that are configured to
automatically minimize or eliminate reflux without depending
entirely on user technique. Further, the prior art focuses on
syringe assemblies designed to deliver medications and not syringe
assemblies that automatically provide additional small amount of
flush solution in the I.V. line at the completion of the flush
procedure.
[0007] Therefore there is a need for a simple, straight forward,
automatic, easy-to-manufacture syringe assembly which helps reduce
or eliminate reflux of blood into the catheter during and after the
flush procedure has occurred even if flush procedures are not
precisely followed. For example, prematurely releasing the
compressive force on the plunger and/or removing the syringe from
the I.V. line before it is clamped, may cause reflux of blood into
the catheter, thus increasing the chance of VAD occlusion.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a syringe assembly for
use in flush applications. The syringe assembly has structure to
provide an additional positive displacement of flush solution after
the flush solution has been substantially delivered from the cavity
in the syringe barrel through the application of an additional
distally-directed force to the plunger.
[0009] An I.V. flush syringe assembly comprises a barrel including
a cylindrical side wall having an inside surface defining a chamber
for retaining fluid, an open proximal end, and a distal end
including a distal wall with an elongate tip extending distally
therefrom having a passageway therethrough in fluid communication
with the chamber. A plunger including an elongate body portion
having a proximal end, a distal end, and a resilient stopper is
slidably positioned in fluid-tight engagement with the inside
surface of the barrel for drawing fluid into and driving fluid out
of the chamber by movement of the stopper relative to the barrel.
The elongate body portion extends outwardly from the open proximal
end of the barrel. The barrel includes structure for moving fluid
distally in the passageway after fluid has been delivered from the
chamber and the stopper is in contact with the distal wall.
[0010] Structure for positively displacing additional fluid after
the stopper has contacted the distal wall of the barrel comprises
the stopper including a distal end having a distal surface and a
proximal end having a cavity therein defining an inside surface.
The distal end of the plunger is connected to the stopper by a
complementary detent structure defining a first detent position and
a second detent position. The detent structure is configured so
that an additional distally-directed force applied to the plunger
after fluid has been delivered from the chamber causes the plunger
to move distally with respect to the stopper from the first detent
position to the second detent position so that a distal tip on the
distal end of the plunger contacts the inside surface of the
stopper forcing part of the distal end of the stopper toward and
preferably into the passageway to move fluid distally in the
passageway.
[0011] The stopper may include a conically-shaped distal surface
and a complementary conically-shaped inside surface of the barrel
distal wall wherein the total included angle of the inside surface
of the barrel at the distal wall is preferably greater than the
total included angle of the stopper distal surface.
[0012] The stopper may include a distally-directed projection on
the distal end of the stopper shaped to fit in the passageway when
the plunger and the stopper are engaged in the second detent
position.
[0013] The inside surface of the stopper may include a
proximally-directed protuberance configured to contact the distal
tip of the plunger when the plunger and the stopper are engaged in
the second detent position.
[0014] The syringe assembly may be configured so that the inside
surface of the stopper includes a first discontinuity, and a second
discontinuity located distally from the first discontinuity. The
distal end of the plunger includes a discontinuity positioned so
that when the stopper and the plunger are in the first detent
position the plunger discontinuity engages the first discontinuity
in the stopper, and when the stopper and the plunger are in the
second detent position, the plunger discontinuity engages the
second discontinuity in the stopper. The discontinuity on the
plunger may be a raised projection and the raised projection may be
shaped like an annular ring or flange. The first discontinuity in
the stopper may be a recess for containing the discontinuity on the
plunger such as an annular recess. The first discontinuity may also
be an inwardly directed projection and the plunger discontinuity a
recess for accepting the projection.
[0015] The syringe assembly may also include flush solution in the
chamber and a tip cap releasably connected to the tip of the
syringe barrel for sealing the passageway. The flush solution may
be selected from the group consisting of saline flush solution and
heparin lock solution.
[0016] The syringe assembly may further include a needle assembly
including a cannula having a proximal end, a distal end, and a
lumen therethrough. A hub having an open proximal end containing a
cavity and a distal end attached to the proximal end of the cannula
so that the lumen is in fluid communication with the cavity of the
hub. The needle assembly is removably attached to the tip of the
barrel through engagement of the tip to the cavity of the hub so
that the lumen is in fluid communication with the chamber of the
barrel.
[0017] The stopper may be made of material selected from the list
consisting of thermoplastic elastomers, natural rubber, synthetic
rubber, thermoplastic materials and combinations thereof.
[0018] The syringe assembly may further include a spring between
the distal tip of the plunger and the distal end of the plunger.
The spring is configured to compress when the plunger moves to the
second detent position with respect to the stopper.
[0019] The syringe assembly may also include the barrel and plunger
having complementary detent structures defining a primary detent
position and a secondary detent position to hold the position of
the plunger relative to the barrel. The primary detent position
being positioned to engage when fluid has been delivered from the
chamber and the stopper is in contact with the distal wall. The
secondary detent position is configured to engage upon application
of an additional distally directed force to the plunger after the
stopper has made contact with the distal wall. The complementary
detent structure between the barrel and the plunger can include the
barrel having a first discontinuity and a second discontinuity
located distally from the first discontinuity, and a proximal end
of the plunger including a discontinuity positioned so that when
the plunger and the barrel are in the primary detent position the
plunger discontinuity engages the first barrel discontinuity and
when the plunger and the barrel are in the secondary detent
position the proximal plunger discontinuity engages the secondary
barrel discontinuity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of a syringe assembly of the
present invention.
[0021] FIG. 2 is a partially cross-sectioned side elevational view
of the syringe assembly of FIG. 1 with a needle assembly
attached.
[0022] FIG. 3 is an enlarged partial cross-sectional side elevation
view of the distal end of the syringe assembly of FIG. 2.
[0023] FIG. 4 is an enlarged partial cross-sectional side
elevational view of the distal end of the syringe assembly shown at
the completion of flush solution delivery.
[0024] FIG. 5 is an enlarged partial cross-sectional side
elevational view of the distal end of the syringe assembly shown
after the completion of flush solution delivery and after the
application of an additional distally-directed force to the
plunger.
[0025] FIG. 6 is a side-elevational view illustrating the syringe
assembly in use with a catheter injection site.
[0026] FIG. 7 is a side-elevational view illustrating the syringe
assembly in use with another catheter injection site.
[0027] FIG. 8 is a partially cross-sectioned side-elevational view
of an alternative syringe assembly of the present invention.
[0028] FIG. 9 is an enlarged partial cross-sectional
side-elevational view of the syringe assembly of FIG. 8.
[0029] FIG. 10 is an enlarged partial cross-sectional
side-elevation view of the syringe assembly of FIG. 8 shown at the
completion of flush solution delivery.
[0030] FIG. 11 is an enlarged partial cross-sectional
side-elevational view of the syringe assembly of FIG. 8 shown after
completion of flush solution delivery and after application of an
additional distally directed force to the plunger.
[0031] FIG. 12 is an enlarged partial cross-sectional
side-elevational view of another alternative embodiment of the
syringe assembly of the present invention shown at the completion
of flush solution delivery.
[0032] FIG. 13 is an enlarged partial cross-sectional
side-elevational view of the syringe assembly of FIG. 12 shown
after completion of the flush solution delivery and after
application of an additional distally directed force to the
plunger.
DETAILED DESCRIPTION
[0033] Referring to FIGS. 1-7, a syringe assembly 20 according to
the present invention generally comprises a barrel 21, including a
cylindrical side wall 22 having an inside surface 23 defining a
chamber 25 for retaining fluid. The barrel further includes an open
proximal end 27 and a distal end 28 having a distal wall 29 with an
elongate tip 31 extending distally therefrom and having a
passageway 32 therethrough in fluid communication with the chamber.
The inside surface of the barrel at the distal wall, indicated as
30, is preferably conically shaped. The distal end of the barrel
preferably, but not necessarily, includes a locking luer type
collar 33 concentrically surrounding tip 31. The collar includes an
inside surface 34 having at least one thread 35 thereon.
[0034] A cannula 43 includes a proximal end 44, a distal end 45 and
a lumen 46 therethrough. The distal end of the cannula may include
a sharp tip or a blunt tip 47 as shown. The cannula may be
connected directly to the tip of the syringe barrel to establish
fluid communication between the lumen and the chamber. Also, the
cannula may be part of a needle assembly 42 including a hub 49
having an open proximal end 50 containing a cavity 51 and a distal
end 52 attached to the proximal end of the cannula so that lumen of
the cannula is in fluid communication with the cavity. The cavity
of the hub can be removably frictionally engaged to the tip of the
barrel.
[0035] A plunger 37 includes an elongate body portion 38, a
proximal end 39 and a distal end 40. A stopper 41 is disposed on
the distal end of the plunger rod through a structure that will be
described in more detail hereinafter. Stopper 41 includes at least
one rib and preferably a plurality of ribs 57 on its outside
diameter. The stopper is slidably positioned in fluid-tight
engagement with the inside surface of the barrel for drawing fluid
into and driving fluid out of the chamber by movement of the
stopper relative to the barrel. Elongate body portion of the
plunger extends outwardly from the open proximal end of the barrel.
Stopper 41 includes a proximal end 58 having a cavity 59 therein
defining an inside surface 60. The stopper further includes a
distal end 61 having a conically shaped distal surface 62 thereon.
Conically-shaped distal surface 62 has a total included angle B as
illustrated in FIG. 4. As will be explained in more detail
hereinafter, total included angle A of the inside surface of the
barrel at the distal wall is preferably greater than the total
included angle B of the conically-shaped distal surface of the
stopper in this embodiment.
[0036] The syringe assembly includes structure for moving fluid
distally in passageway 31 after fluid has been delivered from
chamber 25 and the distal surface of the stopper is in contact with
the distal wall of the barrel.
[0037] The structure for moving fluid distally in the passageway
after fluid has been delivered from the chamber includes the
stopper being connected to the plunger by a complementary detent
structure defining a first detent position and a second detent
position. The detent structure is configured so that a distally
directed force F applied to the plunger after fluid has been
delivered from the chamber causes the plunger to move distally with
respect to the stopper from the first detent position to the second
detent position so that a distal tip 55 on the distal end of the
plunger contacts inside surface 60 of the stopper forcing part of
the distal end of the stopper into passageway 32 to move fluid
distally in the passageway.
[0038] In this embodiment the distal end of the stopper is
preferably shaped to include a distally directed projection 63 on
the distal end of the stopper to fit in passageway 32 when the
plunger and the stopper are engaged in the second detent position
as best illustrated in FIG. 5. In this embodiment, the inside
surface of the stopper preferably includes a proximally direct
protuberance 64 configured to contact distal tip 55 of the plunger
when the plunger and the stopper are engaged in the second detent
position.
[0039] The inside surface of the stopper includes a first
discontinuity and a second discontinuity located distally from the
first discontinuity. The distal end of the plunger includes a
discontinuity position so that when the stopper and the plunger are
in the first detent position the plunger discontinuity engages the
first discontinuity in the stopper and when the stopper and the
plunger are in the second detent position, the plunger
discontinuity engages the second discontinuity in the stopper.
Preferably, the discontinuity at the distal end of the plunger is
at least one raised projection. In this embodiment, the at least
one raised projection is two raised projections configured in the
shape of annular rings 70.
[0040] The first discontinuity in the stopper is preferably at
least one recess for containing the raised projection on the distal
end of the plunger. In this embodiment the at least one recess
includes two recesses which are annularly-shaped recesses 65.
Likewise, the second discontinuity in the stopper is preferably at
least one recess and in this case includes two annularly-shaped
recesses 67.
[0041] The stopper may be made of any material suitable for
providing sealing characteristics while under compression. For
example, the stopper may be made of thermoplastic elastomers,
natural rubber, synthetic rubber or thermoplastic materials and
combinations thereof. The plunger in this embodiment is preferably
made of material which is more rigid than the stopper such as
polypropylene, polyethylene and the like.
[0042] In operation, syringe assembly 20 is connected to a needle
assembly and filled with flush solution using known methods. The
flush solution may be any solution intended for flushing or
maintaining the performance of VAD's. It is preferred that the
flush solution be selected from the group consisting of saline
flush solution and heparin lock flush solution. These solutions are
known in the art and readily available. An example of a saline
flush solution is 0.9% Sodium Chloride USP for injection. An
example of a heparin lock flush solution is 0.9% Sodium Chloride
with 100 USP units of Heparin Sodium per ml or 10 USP units of
Heparin Sodium per ml. The syringe with needle assembly attached is
used to pierce the pierceable septum or a blunt cannula may be
inserted into a pre-split septum of a vial or the neck of a glass
ampule containing flush solution, and the flush solution is drawn
into the syringe barrel by pulling plunger flange 56 in the
proximal direction while holding barrel 21, to draw fluid through
the needle cannula into fluid chamber 25.
[0043] Alternatively, large numbers of flush syringes may be
pre-filled with flush solution during the manufacturing of the
syringe using sterile filling methods. Such prefilled syringes may
be supplied with a tip cap, such as tip cap 36 releasably connected
to tip 31 sealing passageway 32. It is preferred that the tip cap
is formed of material selected from a group of thermoplastic
materials and elastomeric materials such as natural and synthetic
rubber, thermoplastic elastomers, or combinations thereof.
[0044] The syringe is now ready for use in flushing a catheter of
an I.V. set. I.V. sets can be very complicated and may include
multiple injection ports, a valve and/or other components. For the
purpose of illustrating the present invention a simplified I.V. set
73 is illustrated in FIG. 6. I.V. set 73 comprises an I.V. site 74
which includes a housing 75 having a hollow interior 76 and a
septum 77 at its proximal end. An I.V. line 79 having a conduit
therethrough extends from the distal end of the housing. For this
I.V. set septum 77 is pre-slit for use with blunt cannula. The I.V.
site may be a valve having structure for accepting the syringe
barrel tip and being activated by the insertion of the tip to
establish fluid communication with the catheter, such as the valve
taught in U.S. Pat. No. 6,171,287.
[0045] Blunt tip 47 of cannula 43 may be inserted through pre-split
septum 77 of I.V. set 73. Alternatively, a sharp tip of a needle
cannula may be used to pierce a septum that is not pre-split, or
the tip of the barrel may be engaged with a valve in the IV site.
This establishes fluid communication between the interior 76 of the
I.V. set and the chamber of the syringe barrel. The syringe barrel
21 is preferably held via finger grips 53. Pressure is then applied
to flange 56 of the plunger, for example by a thumb, in the distal
direction. This moves plunger 37 having the stopper 41 on its
distal end forcing the liquid such as flush solution 71 in chamber
25 out of the chamber, through cannula 43 and into interior 76 of
the I.V. set and then through I.V. line 79.
[0046] Referring to FIG. 4 the position of the plunger and stopper
at the completion of the flush procedure is shown. At the
completion of the flush procedure conically shaped distal surface
62 of the stopper contacts conically-shaped inside surface 30 of
the distal end wall of the barrel near passageway 31 sealing the
passageway, and the stopper remains attached to the plunger at the
first detent position. It should be noted that because the total
included angle A of the inside surface of the barrel at the distal
wall is greater than total included angle B of the conically-shaped
distal surface of the stopper in this embodiment, the stopper tends
to contact the inside surface near the passageway and seals the
passageway. Any incidental flexure of the stopper after the
passageway is sealed will not likely create reflux. This is the
preferred relationship between the stopper and the barrel. However,
this relationship, although preferred, is not necessary to produce
the positive displacement of flush solution provided by the present
invention. In the embodiment of FIGS. 1-5 the total included angle
of the inside surface of the barrel is less than the total included
angle of the conically-shaped distal surface of the stopper.
[0047] At this point, while clamping the I.V. line, the user
applies distally directed force F 25 to flange 56 of the plunger as
illustrated in FIG. 5. Additional force F will cause the plunger to
move distally with respect to the stopper from the first detent
position to the second detent position so that distal tip 55 on the
distal end of the plunger contacts the inside surface of the
stopper forcing part of the distal end of the stopper into the
passageway to move fluid distally in the passageway. In particular,
in this embodiment, distal tip 55 contacts 30 proximally-directed
protuberance in the stopper cavity deflecting the resilient stopper
material so that distally directed projection 63 enters passageway
32 of the barrel tip forcing fluid distally through the I.V. set.
The positive displacement of fluid in the passageway in a distal
direction will help prevent reflux while the I.V. line is being
clamped and the syringe is being removed. After the I.V. line is
clamped, the empty syringe assembly may be removed from the I.V.
set.
[0048] FIG. 7 shows an alternative simplified I.V. set to
illustrate a flush procedure without a needle assembly. In FIG. 7,
I.V. set 173 comprises an I.V. site 174 which includes a housing
175 having a hollow interior 176 and a luer fitting 178 at its
proximal end. An I.V. line 1 79 having a conduit therethrough
extends from the distal end of the housing. T he example
illustrated in FIG. 7 is simplified to demonstrate the invention.
In most cases a luer fitting such as luer fitting 178 would be part
of a one-way valve in the I.V. set. The elongate tip of the barrel
is inserted and engaged with the luer fitting to establish fluid
communication between interior 176 of the I.V. set and the chamber
of the syringe barrel. Pressure is then applied to flange 56 on the
plunger, for example by a thumb, in the distal direction. This
moves plunger 37 having stopper 41 on its distal end forcing liquid
such as flush solution 71 in chamber 25 out of the chamber, through
passageway 32 in the elongate tip into hollow interior 176 of the
I.V. set and then through I.V. line 179. The remainder of the flush
procedure is substantially identical to the procedures described
when using I.V. set 73 of FIG. 6.
[0049] FIGS. 8-11 illustrate an alternative embodiment of the
syringe assembly of the present invention. In this embodiment
syringe assembly 120 comprises a barrel 121 including a cylindrical
side wall 122 having an inside surface 123 defining a chamber 125
for retaining fluid. The barrel includes an open proximal end 127
and a distal end 128 including a distal wall 129 with an elongate
tip 131 extending distally therefrom and having a passageway 132
therethrough in fluid communication with the chamber. A tip cap 136
is releasably connected to elongate tip 131 for sealing passageway
132.
[0050] A plunger 137 includes an elongate body portion 138 having a
proximal end 139, a distal end 140 and a resilient stopper 141. A
quantity of flush solution 71 is contained within the chamber. The
stopper is slidably positioned in fluid-tight engagement with the
inside surface of the barrel for drawing fluid into and driving
fluid out of the chamber by movement of the stopper relative to the
barrel. Part of the elongate body portion of the plunger extends
outwardly from the open proximal end of the barrel.
[0051] Syringe assembly 120 includes structure for moving fluid
distally in the passageway after fluid has been delivered from the
chamber and the stopper is in contact with the distal wall. This
structure includes the stopper having a distal end 161 with a
distal surface 162. The stopper further includes a proximal end 158
having a cavity 159 therein defining an inside surface 160. The
distal end of the plunger is connected to the stopper by a
complementary detent structure defining a first detent position and
a second detent position. A detent structure is configured so that
a directed force F applied to the plunger after fluid has been
delivered from the chamber causes the plunger to move distally with
respect to the stopper from the first detent position to the second
detent position so that a distal tip 155 on the distal end of the
plunger contacts the inside surface of the stopper forcing part of
the distal end of the stopper into the passageway to move fluid
distally in the passageway. In this embodiment spring 180 is
positioned between distal tip 155 and the distal end of the plunger
rod. The spring is configured to compress when the plunger moves to
the second detent position with respect to the stopper.
[0052] In this embodiment the first detent position is defined by
an annular projection 170 on the plunger and an annular recess 165
inside the stopper sized to receive annular projection 170. The
second detent position is defined by annular projection 170 and a
second annular recess 167 in the stopper. It should be noted that
the stopper may be made of more than one piece and more than one
material. In this embodiment, a distal end of the stopper is made
of resilient material and the proximal end is formed of relatively
rigid material such as thermoplastic.
[0053] This embodiment contains an additional detent system for
controlling the relative position of the plunger with respect to
the barrel consisting of a primary detent position and a secondary
detent position. The primary detent position is located to engage
when fluid has been delivered from the chamber and the stopper is
in contact with the distal wall as best illustrated in FIG. 10. The
secondary detent position is engaged upon application of an
additional distally directed force to the plunger as illustrated in
FIG. 11. When the stopper and the plunger are in the second detent
position the plunger and the barrel are in the secondary detent
position. In this embodiment, the primary detent position is
defined by proximal flange 156 on the plunger and annular recess
181 in the proximal end of the barrel. The secondary detent
position is defined by flange 156 and a second annular recess 182
in the proximal end of the barrel as illustrated in FIG. 11. The
primary and secondary detent positions between the plunger and the
barrel can be defined by any combination of complementary
structures such as projections, recesses, ratchets, mechanical
structures or breaking structures and the flange and recess
combination illustrated in this embodiment merely representative of
the many possibilities that are within the purview of the present
invention. It is also within the scope of the present invention to
include an embodiment having only structure for the secondary
detent position and not the primary detent position. In this
configuration the application of additional force to the plunger
after flush solution has been delivered to the catheter, causes the
stopper and the plunger to engage in the second detent position and
the barrel and the plunger to engage in the secondary detent
position. The additional detent system having both a primary and a
secondary detent position is preferred when using a stopper having
a conically-shaped distal surface and a barrel having a
conically-shaped distal wall when the total included angle of the
stopper distal surface is equal or greater than the total included
angle of the inside surface of the barrel at the distal wall.
[0054] In use, this alternate embodiment functions substantially
similarly to the preferred embodiment of FIGS. 1-5. The addition of
the spring allows more latitude in the design of the product since
the material of the stopper does not necessarily have to perform
the spring function as in the preferred embodiment.
[0055] FIGS. 12 and 13 illustrate another alternative embodiment of
the syringe assembly of the present invention. In this embodiment,
syringe assembly 220 functions similarly to the embodiment of FIGS.
8-11 except for the structure of the additional detent system for
controlling the relative position of the plunger with respect to
the barrel. In this alternative embodiment the additional detent
system consists of a primary detent position and a secondary detent
position. The primary detent position is located to engage when
fluid has been delivered from the chamber and the stopper is in
contact with the distal wall as illustrated in FIG. 12. The
secondary detent position is engaged upon application of an
additional distally directed force F to the plunger as illustrated
in FIG. 13. When the stopper and the plunger are in the second
detent position, the plunger and the barrel are in the secondary
detent position. In this embodiment, the primary detent position is
established by flexible element 287. The flexible element is
connected to or integrally formed with plunger 237 at proximal end
239. Flexible element 287 includes proximally-directed radial
projections 288 and 289 having sharp ends 291 and 292
respectively.
[0056] In this embodiment, the primary detent position is defined
by the sharp ends of radial projections 288 and 289 and inside
surface 223 of the barrel at the proximal end of the barrel as
illustrated in FIG. 12. The secondary detent position is defined by
the sharp ends of the radial projections and a portion of inner
surface 223 of barrel 221 which is positioned distally from the
primary detent position as illustrated in FIG. 13. In this
embodiment the secondary detent position can occur at any position
which is distal to annular projection 293. This structure is less
tolerance-dependent because the detent positions can occur over a
range of positions within the barrel. The flexible element 287 may
be made of sheet metal such as stainless steel. The harder metal
will enhance the grip of the sharp ends of the projections to
resist proximal motion of the plunger with respect to the barrel.
The flexible element may be circularly shaped like a flexible
flange so that the sharp edge can go up to 360 degrees around the
plunger. Further, one or more projections may radiate from the
proximal end of the stopper so long as the net result is the
restraint of the motion of the plunger with respect to the barrel.
Discontinuities such as recesses and/or projections may also be
placed in the barrel to enhance the function of the radial
projections.
* * * * *