U.S. patent number RE36,273 [Application Number 08/967,556] was granted by the patent office on 1999-08-17 for syringe apparatus for separating blood.
This patent grant is currently assigned to Vascular Logics, Inc.. Invention is credited to James K. Brannon.
United States Patent |
RE36,273 |
Brannon |
August 17, 1999 |
Syringe apparatus for separating blood
Abstract
A disposable syringe for the dual extraction of arterial blood
or venous blood into the barrel of said disposable syringe and a
plurality of vacuum glass tubes. The distal portion of the syringe
has an inner cannula extending centrally retrograde from the distal
portion of the syringe and telescoping into the proximal portion of
a conduit of a plunger of the syringe with said plunger of the
syringe having a piston which sealably slides lengthwise about said
inner cannula and said conduit of said plunger further having one
end thereof sealably accepting a blood collection needle of a blood
collection receptacle with said inner cannula telescoping further
centrally retrograde into said conduit of said plunger with the
distal portion of said inner cannula being securely positioned into
the distal portion of the syringe so as to allow arterial or venous
blood to flow around said inner cannula and into the barrel of the
syringe when said plunger is advanced proximally with said inner
cannula inducing the flow of arterial or venous blood when a vacuum
glass tube is inserted into said blood collection receptacle.
Several embodiments of the inner cannula plunger-conduit system are
described.
Inventors: |
Brannon; James K. (Culver City,
CA) |
Assignee: |
Vascular Logics, Inc.
(Huntington Beach, CA)
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Family
ID: |
23691861 |
Appl.
No.: |
08/967,556 |
Filed: |
November 12, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
426702 |
Apr 24, 1995 |
05518005 |
May 21, 1996 |
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Current U.S.
Class: |
600/578;
604/231 |
Current CPC
Class: |
A61B
5/15003 (20130101); A61B 5/150389 (20130101); A61B
5/154 (20130101); A61B 5/155 (20130101); A61B
5/150244 (20130101); A61B 5/150511 (20130101); A61B
5/150992 (20130101); A61B 5/153 (20130101); A61B
5/150213 (20130101); A61B 5/150351 (20130101); A61B
5/150572 (20130101) |
Current International
Class: |
A61B
5/15 (20060101); A61B 5/155 (20060101); A61B
005/00 () |
Field of
Search: |
;600/573,576-579
;604/184,187,192,205,231 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3025800 A1 |
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Feb 1982 |
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DE |
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WO 88/03778 |
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Jun 1988 |
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WO |
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Primary Examiner: Hindenburg; Max
Attorney, Agent or Firm: Lyon & Lyon LLP
Claims
Having thus described the invention what I desire to claim and
secure by Letters Patent is:
1. A syringe for the extraction of a fluid into at least one fluid
chamber or the injection of a fluid comprising:
(a) a cylindrical body having a distal end and an open proximal
end, said distal end including a partial opening and a portion of a
size and shape adapted for mounting an indwelling catheter thereon,
said distal end being open to the flow of a first fluid into and
out of said cylindrical body through said partial opening at all
times when said syringe is in use;
(b) a piston sealably engaging and slidable along the interior wall
of said cylindrical body, said piston including a piston face
extending transversely across said interior wall and defining a
fluid chamber between said piston face and said distal end of said
cylindrical body;
(c) plunger means for moving said piston proximally or distally
within said cylindrical body, said plunger means being attached at
one end to said piston, said plunger means having another end
extending beyond said open proximal end of said cylindrical body,
said plunger means having a size and shape that minimizes
substantial lateral motion in said cylindrical body;
(d) extending distally and not beyond said distal end, an inner
cannula having a blunt distal orifice and a blunt proximal orifice,
said inner cannula further having an interior portion, said
interior portion having a substantially narrow, uniform internal
diameter adapted for passing a separate second fluid therethrough,
said inner cannula further having an exterior portion, said inner
cannula being rigidly held in said distal end by support means so
as to position substantially permanent said blunt distal orifice in
said partial opening, said inner cannula being integral with said
support means so as to be able to allow the flow of said first
fluid past said blunt distal orifice and into and out of said fluid
chamber, said inner cannula further being rigidly held in said
distal end by support means to assure said first fluid remains
substantially separate from said interior portion, said inner
cannula further being rigidly held in said distal end by support
means so as to substantially prevent the flow of said first fluid
through said inner cannula, said blunt distal orifice further being
positioned by support means to allow mounting of said indwelling
catheter on said portion; and
(e) operatively disposed in relationship to said blunt proximal
orifice, sealing means for preventing the retrograde flow of air
into said inner cannula, said sealing means comprising a fluid
collection receptacle, said fluid collection receptacle including a
passage that communicates with said interior portion of said inner
cannula.
2. A syringe as defined in claim 1 wherein said inner cannula,
further extending proximally and centrally into said cylindrical
body, further being integral with said support means so as to be
able to allow the flow of said first fluid around said exterior
portion of said inner cannula and into and out of said fluid
chamber.
3. A syringe as defined in claim 1 wherein said piston further
includes a central opening of a size and shape adapted for slidably
and sealably engaging said exterior portion of said inner cannula
at all times.
4. A syringe as defined in claim 1 wherein said plunger means
includes conduit means extending proximally and distally through
said plunger means, said conduit means including an open distal
end, said conduit means further including an open proximal end
being sealably engaged by said fluid collection receptacle, said
conduit means having a sufficiently wide internal diameter to allow
the passage of said inner cannula therethrough at all times, said
conduit means further having a uniform internal diameter to induce
the passage of said separate second fluid through said inner
cannula and said plunger means and into said fluid collection
receptacle.
5. A syringe for the extraction of a fluid into at least one fluid
chamber or the injection of a fluid comprising:
(a) a cylindrical body having a distal end and an open proximal
end, said distal end including a partial opening and a portion of a
size and shape adapted for mounting an indwelling catheter thereon,
said distal end being open to the flow of a first fluid into and
out of said cylindrical body through said partial opening at all
times when said syringe is in use;
(b) extending distally and not beyond said distal end, an inner
cannula having a blunt distal orifice and a blunt proximal orifice,
said inner cannula further having an interior portion, said
interior portion having a substantially narrow, uniform internal
diameter adapted for passing a second fluid therethrough, said
inner cannula further having an exterior portion, said inner
cannula being rigidly held in said distal end by support means so
as to position substantially permanent said blunt distal orifice in
said partial opening, said inner cannula being integral with said
support means so as to be able to allow the flow of said first
fluid past said blunt distal orifice, said inner cannula further
being rigidly held in said distal end by support means to assure
said first fluid remains substantially separate from said interior
portion, said inner cannula further being rigidly held in said
distal end by support means so as to substantially prevent the flow
of said first fluid through said inner cannula, said blunt distal
orifice further being positioned by support means to allow mounting
of said indwelling catheter on said portion;
(c) plunger means having piston means at one end of said plunger
means, said piston means sealably engaging and slidable along the
interior wall of said cylindrical body, said piston means including
a portion extending transversely across said interior wall and
defining a fluid chamber between said piston means and said distal
end of said cylindrical body, said plunger means, disposed within
said cylindrical body, being adapted for moving said piston means
proximally or distally so as to induce the flow of said first fluid
past said blunt distal orifice and into and out of said fluid
chamber, said plunger means having another end extending beyond
said open proximal end of said cylindrical body, said plunger means
having a size and shape that minimizes substantial lateral motion
in said cylindrical body; and
(d) operatively disposed in relationship to said blunt proximal
orifice, sealing means for preventing the retrograde flow of air
into said inner cannula, said sealing means comprising a fluid
collection receptacle, said fluid collection receptacle including a
passage that communicates with said interior portion of said inner
cannula.
6. A syringe as defined in claim 5 wherein said inner cannula,
further extending proximally and centrally throughout said
cylindrical body, further being integral with said support means so
as to be able to allow the flow of said first fluid around said
exterior portion of said inner cannula and into and out of said
fluid chamber.
7. A syringe as defined in claim 5 wherein said piston means
further includes means for separating said first fluid from said
second fluid, said separating means comprising a central opening
having a size and shape adapted for slidably and sealably engaging
said exterior portion of said inner cannula at all times.
8. A syringe as defined in claim 5 wherein said plunger means
includes conduit means extending proximally and distally through
said plunger means, said conduit means including an open distal
end, said conduit means further including an open proximal end
being sealably engaged by said fluid collection receptacle, said
conduit means having a sufficiently wide internal diameter to allow
the passage of said inner cannula therethrough at all times, said
conduit means further having a uniform internal diameter to induce
the passage of said second fluid through said inner cannula and
said plunger means and into said fluid collection receptacle.
.Iadd.
9. A syringe for the extraction of a fluid into at least one fluid
chamber or the injection of a fluid comprising:
(a) a cylindrical body having a distal end and an open proximal
end, said distal end including an opening therethrough, said
opening being adapted to allow flow of a first sample liquid into
and out of said cylindrical body through said opening;
(b) a piston sealably engaging and slidable along an interior wall
of said cylindrical body, said piston including a piston face
extending transversely across said interior wall and defining a
fluid chamber between said piston face and said distal end of said
cylindrical body;
(c) a plunger attached to a proximal end of said piston, said
plunger extending proximally beyond said open proximal end of said
cylindrical body, said plunger being adapted to move said piston
proximally or distally within said cylindrical body; and
(d) an inner cannula extending proximally from said distal end, and
having a distal orifice and a proximal orifice, said inner cannula
further having an interior channel adapted for passing a second
sample liquid therethrough, said inner cannula being held in said
distal end by a support therein so as to retain in position
substantially permanently said distal orifice in said opening, said
inner cannula being adapted to allow the flow of said first sample
liquid past said distal orifice and into and out of said fluid
chamber, while assuring that said first sample liquid remains
substantially separate from said interior
channel..Iaddend..Iadd.10. The syringe of claim 9, further
comprising a fluid collection receptacle including a passage that
communicates with said interior channel of said inner
cannula..Iaddend..Iadd.11. A syringe for extracting an isolated
sample of fluid, said syringe comprising:
a cylindrical body having an interior wall, an open proximal end,
and a distal end, said distal end having a distal opening
therethrough;
a plunger assembly slidably disposed in said proximal end, said
plunger assembly sealably engaging said interior wall of said
cylindrical body, thereby defining a fluid chamber between a distal
face of said plunger assembly and said distal end of said
cylindrical body; and
a cannula attached in said cylindrical body, and extending
proximally from said distal end, said cannula having a distal
orifice, said distal orifice being adapted to allow a first fluid
sample to be drawn through said distal opening into said fluid
chamber, said cannula having an interior channel communicating with
said distal orifice allowing a second fluid sample to be drawn
through said distal opening into said interior channel, while
remaining substantially separate from said first fluid
sample..Iaddend..Iadd.12. The syringe of claim 11, wherein said
distal face of said plunger assembly includes an opening therein,
and wherein said cannula extends proximally into said opening, said
opening being adapted to slidably and sealably engage said
cannula..Iaddend..Iadd.13. The syringe of claim 12, wherein said
plunger assembly includes a conduit therein extending proximally
from said opening in said distal face, said conduit being adapted
to allow said second fluid sample in said cannula to pass
therethrough..Iaddend..Iadd.14. The syringe of claim 13, further
comprising a fluid collection receptacle on a proximal end of said
plunger assembly in communication with said
conduit..Iaddend..Iadd.15. The syringe of claim 13, further
comprising a blood collection needle extending proximally from said
conduit..Iaddend..Iadd.16. The syringe of claim 11, wherein said
distal orifice of said cannula is attached to said distal end of
said cylindrical body by an integral support..Iaddend..Iadd.17. The
syringe of claim 11, wherein said interior channel has a
substantially narrow, uniform diameter..Iaddend..Iadd.18. A syringe
for extracting an isolated sample of fluid, said syringe
comprising:
a cylindrical body having an interior wall, an open proximal end,
and a distal end, said distal end having a distal opening
therethrough;
a piston slidably disposed in said proximal end, said piston
sealably engaging said interior wall of said cylindrical body,
thereby defining a fluid chamber between a piston face of said
piston and said distal end of said cylindrical body;
a plunger attached to said piston and extending proximally
therefrom, said plunger being adapted to move said piston
proximally and distally within said cylindrical body; and
a cannula attached to said distal end of said cylindrical body and
extending proximally therefrom, said cannula having a cross-section
smaller than a cross-section of said distal opening, thereby
allowing a first fluid sample to be drawn into and out of said
fluid chamber through said distal opening, said cannula having an
interior channel allowing a second fluid sample to be drawn
therethrough while remaining substantially
separate from said first fluid sample..Iaddend..Iadd.19. The
syringe of claim 18, wherein said cannula includes a distal end
having a distal orifice therein, said distal orifice communicating
with said interior channel, said distal orifice being located
adjacent said distal opening..Iaddend..Iadd.20. The syringe of
claim 19, wherein said distal end of said cannula is fixedly
attached in said distal opening by a support..Iaddend..Iadd.21. The
syringe of claim 18, further comprising a conduit extending
proximally from an opening in said piston face through said
plunger, said cannula sealably and slidably telescoping into said
conduit, thereby allowing said second fluid sample to pass through
said conduit..Iaddend..Iadd.22. The syringe of claim 21, further
comprising a fluid collection receptacle on a proximal end of said
plunger, said fluid collection receptacle sealably communicating
with said
conduit..Iaddend..Iadd.23. The syringe of claim 22, wherein said
fluid collection receptacle includes a vacuum tube attachable to
said fluid collection receptacle, thereby allowing said second
fluid sample to be received within said vacuum
tube..Iaddend..Iadd.24. The syringe of claim 21, further comprising
a blood collection needle extending proximally from a proximal end
of said plunger and being sealably housed in a sleeve, said blood
collection needle communicating with said conduit, said blood
collection needle being adapted to detachably receive a vacuum tube
thereon..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a syringe having an inner cannula
integral with the distal portion of said syringe and a piston
sealably engaging said inner cannula with said piston integral with
a plunger-conduit system. The inner cannula is integral with the
distal portion of the syringe and positioned therein so as to allow
a fluid to flow around said inner cannula and into the barrel of
the syringe when said piston is advanced proximally and in so
doing, this first obtained fluid is separate from a second fluid
which can be obtained by inserting a vacuum glass tube into a fluid
collection receptacle attached to the plunger conduit system. After
a plurality of vacuum tubes are filled with the second obtained
fluid, the first obtained fluid can be returned to the patient by
simply advancing the piston distally.
2. Information Disclosure Statement
Since the advent of the Acquired Immune Deficiency Syndrome (AIDS),
many disposable devices have been developed to prevent accidental
needle sticks. However, prior art lacks simplicity and blood
drawing procedures found traditionally cumbersome are now made
unusually complex. Yet even further, as cost containment becomes
more important, the additional blood drawing components found in
prior art touted as being safe are now realized to be unusually
complex, not universally applicable, and consequently not cost
worthy.
Often, severely ill patients in the hospital will require central
venous catheterization for administration of various medicinal
preparations and arterial catheterization for monitoring of blood
pressure.
Regarding central venous catheterization, often a triple lumen
catheter will be placed in the patient's subclavian vein and at
least one lumen of the catheter is used for the administration of
fluid; the two remaining unused lumens may be used to draw blood
for laboratory testing or alternately the administration of a
variety of other medicinal preparations. If a given lumen of the
central venous catheter is used to obtain a blood sample for
laboratory testing, a syringe is attached to the unused lumen and
this first obtained venous blood considered too dilute for
laboratory testing is drawn into the barrel of the syringe, the
syringe is then detached and discarded. A second syringe is then
attached to this lumen and a second obtained volume of venous blood
is drawn into the barrel of the syringe. The volume of venous blood
obtained is limited by the volume of the syringe. This second
obtained venous blood is then transferred to vacuum glass tubes by
cumbersome traditional methods.
Regarding arterial catheterization, an arterial catheter is
inserted into the patient's radial artery. The now inserted
arterial catheter can then be attached to a blood pressure monitor.
The connection to the blood pressure monitor is established with
pressure tubing having at least one three-way valve proximal to the
catheter insertion site. When monitoring blood pressure,
heparinized solution fills the pressure tubing to the level of the
catheter insertion site distally and a pressure transducer
proximally. In the monitoring mode, the three-way valve is patent
with the distal catheter and the proximal pressure transducer.
Simultaneously, the three-way valve is closed to a blood sampling
side port used to obtain blood samples for laboratory testing. To
obtain blood for laboratory testing, the three-way valve is closed
toward the proximal pressure transducer and patent toward the
distal catheter and the blood sampling side port. Thereafter, a
syringe is attached to the blood sampling side port and a first
obtained volume of arterial blood considered too dilute for
laboratory testing is drawn into the barrel of the syringe and the
syringe is then detached. A second syringe is then attached to the
blood sampling side port and a second obtained volume of arterial
blood is drawn into the barrel of the syringe. This second obtained
volume of arterial blood considered appropriate for laboratory
testing is transferred to vacuum glass tubes in a traditional
manner found to be cumbersome and unusually complex by those
familiar with prior art. The three-way valve is then positioned to
make patent the arterial catheter distally and the pressure
transducer proximally so that the patient's blood pressure can be
continuously monitored.
In view of the aforementioned cumbersome manipulations and
unusually complex devices used to obtain a single sample of venous
or arterial blood from an indwelling catheter, the objectives of
the present invention are set forth and described herein.
In preparation for this application, a search was completed in
Class 604, Subclass 231 and 187, Class 128, Subclass 214.4. In
contradistinction to the patent application at hand U.S. Pat. No.
4,274,408 of Nimrod teaches a displaceable feeder tube contained
within a syringe barrel having a function readily distinguishable
from that which follows.
SUMMARY AND OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide an improved
method for obtaining a plurality of blood samples for vacuum glass
tubes from indwelling arterial or venous catheters from a single
syringe apparatus.
It is an object of the present invention to provide means for
separating a first obtained volume of blood considered too dilute
for laboratory testing from a second obtained volume of blood
considered appropriate for laboratory testing using a single
syringe.
It is an object of the present invention to provide a single
syringe apparatus that can be attached to an indwelling central
venous catheter or an indwelling arterial catheter for purposes of
obtaining a plurality of blood samples.
SUMMARY
The invention describes a syringe apparatus having an inner cannula
positioned securely in the distal portion of said syringe apparatus
so as to allow fluid to flow past the inner cannula and into the
barrel of the syringe. This first obtained fluid considered too
dilute for testing remains separate from a second obtained fluid
which passes through the inner cannula, a plunger-conduit system
and into a plurality of vacuum glass tubes inserted into a blood
collection receptacle integral with the plunger-conduit system. The
piston of the syringe apparatus sealably engages the inner cannula
and slides lengthwise about the inner cannula when the
plunger-conduit system is advanced in a proximal or distal
direction. The outer-diameter of the inner cannula is smaller than
the inner diameter of the plunger-conduit system and thereby
facilitates telescoping of the inner cannula within the
plunger-conduit system when the plunger conduit system is advanced
in a proximal or distal direction while the piston of the syringe
apparatus keeps separate a first obtained fluid considered too
dilute for laboratory testing from a second obtained fluid
considered appropriate for laboratory testing induced to pass
through the inner cannula and the plunger-conduit system when a
plurality of vacuum glass tubes are inserted into a blood
collection receptacle integral with the plunger-conduit system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of the syringe of the present invention
with the piston thereof positioned proximally to show the inner
cannula within the syringe tip distally and the plunger-conduit
system proximally;
FIG. 2 is an exploded cross section view of the distal portion of
the syringe of this invention;
FIG. 3 is a sectional view of the syringe of the present invention
attached to arterial pressure tubing at a side blood sampling
port;
FIG. 4 is a sectional view of the syringe of the present invention
with first obtained fluid within the barrel of the syringe;
FIG. 5 is a sectional view of the syringe of the present invention
showing a second obtained fluid within the inner cannula, the
plunger-conduit system and a vacuum glass tube;
FIG. 6 is a sectional view of the syringe of the present invention
showing the first obtained fluid having been returned to the
patient;
FIG. 7 is a sectional view of the syringe of the present invention
showing the three-way valve positioned to allow continuous
monitoring of a patient's blood pressure;
FIG. 8 is an alternate embodiment of the distal portion of the
syringe of the present invention with the inner cannula having a
side opening within the fluid chamber.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The apparatus of the present invention is exemplified by the
embodiment of FIG. 1, which shows a syringe type device with a
customary cylindrical body 10 terminating at an end wall 82
integral with a distal hub 34. Integral with the distal hub 34 is a
supporting bar 30 which partially occludes a hub opening 32. The
support bar 30 rigidly holds and prevents axial or lateral movement
of an inner cannula 28. The inner cannula 28 has origin at the
distal hub 34 and not beyond and extends proximally and not beyond
a thumb rest 80 which is integral with the cylindrical body 10. The
piston 14 is mounted to the plunger 20 at a piston mounting face 18
with the piston 14 having been fitted into the proximal end of the
cylindrical body 10 to establish a fluid seal at the juncture
thereof and the interior wall 12 of the cylindrical body 10. The
piston 14 has a fluid-chamber face 16 which establishes a fluid
chamber 36 through which the inner cannula 28 passes. The outer
diameter of the inner cannula 28 is substantially larger than the
inner diameter of the central opening 24 of the piston 14 so as to
create a slidable fluid seal at the juncture thereof and the outer
diameter of the inner cannula 28. The inner cannula 28 has a
substantially narrow inner diameter defined by a smooth inner wall
78. The outer diameter of the inner cannula 28 is substantially
smaller than the inner diameter of the conduit 22 so as to allow
telescoping of the inner cannula 28 into the conduit 22 of the
plunger 20 when the plunger is advanced in a proximal or distal
direction. At the proximal end of the conduit 22 is a funnel shaped
opening 26 to which a blunt blood collection needle 46 integral
with a blood collection receptacle 52 is sealably mounted. Often,
blunt blood collection needles of this variety have a proximal
needle 48 housed within a rubber sleeve 50. The cooperative
functional elements define the fluid chamber 36 which is
substantially separate from a fluid chamber 88.
The distal hub 34 is further exemplified in FIG. 2 to show the
support bars 30 in cross section partially occluding the hub
opening 32. The hub opening 32 freely communicates with the fluid
chamber 36 as shown in FIG. 1.
The functional and operative position of the syringe apparatus is
shown in FIG. 3 wherein a blood sampling side port 40 is mounted to
the distal hub 34. A three-way valve 42 having an off indicator tip
44 is integral with a distal port 54 and proximal port 62. In the
operative position shown the distal port 54 and the proximal port
62 freely communicate. Integral with the distal port 54 is a
transparent pressure tube 68 which is attached to a patient's
radial artery 64 of a wrist 76. The pressure tube 68 contains a
first obtained fluid 70 which is partially mixed with a second
obtained fluid 66. Integral with the proximal port 62 is the
transparent pressure tube 68 attached to a fluid reservoir 74 and a
pressure transducer 72 with a blood pressure reading of 120/80.
FIG. 4 shows the three-way valve 42 with the off indicator tip 44
directed toward the proximal port 62 thereby allowing the distal
port 54 to freely communicate with the blood sampling side port 40.
The piston 14 has been advanced proximally for purposes of drawing
the first obtained fluid 70 considered too dilute for laboratory
testing into the fluid chamber 36 as shown in FIG. 1. A
substantially minimal amount of first obtained fluid 70 is drawn
into the inner cannula 28 having a substantially narrow inner
diameter defined by an inner wall 78. The second obtained fluid 66
is now at rest at the distal hub opening 32.
FIG. 5 shows the second obtained fluid 66 considered appropriate
for laboratory testing having passed through the inner cannula 28,
the conduit 22 of the plunger 20 and into a vacuum glass tube 82
having a rubber plug 84 when the needle 48 is caused to penetrate
the rubber plug 84. The first obtained fluid 70 remains
substantially separate from the second obtained fluid 66 when the
vacuum glass tube 82 is inserted into the proximal end of the blood
collection receptacle 52.
FIG. 6 shows the first obtained fluid 70 considered too dilute for
laboratory testing having been returned to the patient's radial
artery.
FIG. 7 shows the three-way valve 42 with the off indicator tip 44
directed toward the blood sampling side port 40 so as to allow the
pressure transducer 72 to record the patient's blood pressure.
FIG. 8 is an exploded view of an alternative embodiment of the
distal hub 34. The inner cannula 28 is integral with the distal hub
34 such that only a single distal opening 90 allows fluid to enter
the fluid chamber 36 via a side opening 92 integral with the inner
wall 78 of the inner cannula 28. The distinctive operative elements
require manual positioning of the plunger 20 to prevent forward
displacement of the piston 14 when the vacuum glass tube 82 is
inserted into the proximal end of the blood collection
receptacle.
It will be appreciated that the method and apparatus illustrated
above enable the benefits of obtaining a plurality of blood samples
from second obtained fluid to be enjoyed using a single syringe.
The collection of blood samples from indwelling catheters is
universally made safe, simple, efficient and cost effective. The
syringe apparatus of this invention makes a traditionally
cumbersome and time consuming procedure a welcomed necessity.
* * * * *