Safety syringe abstract
Three versions of a safety syringe are disclosed which can be used
as a Pressure Sampler syringe, an Aspiration Sampler syringe, or
a regular Hypodermic Injection syringe. The device has a manually
retractable needle which withdraws to inside the syringe after use;
thus, protecting the user from accidental stabbing by an exposed
used needle. The syringe plunger can still function to expel entrained
fluids after the used needle is retracted to the "safe"
position, which allows the syringe to be used as a blood gas analysis
sampler. Additionally the sampler versions of the syringe will completely
seal the sampled fluid from the atmosphere, thus assuring no contamination
of the sample. The device consists of three basic parts, a retractable
needle and seal assembly, a standard syringe barrel, and a modified
plunger which stores the retracted needle.
Safety syringe claims
I claim a safety syringe with a retractable needle comprising:
1. A syringe and needle assembly to be configured in a first position
with the needle extended for use and a second position with the
needle safely retracted, comprising:
a barrel assembly having an elongate hollow tubular barrel with
an interior surface and an exterior surface, a longitudinal axis,
a first end, and an open second end, having a wall interconnected
across said first end of said barrel, said wall having an aperture
extending therethrough, having a nipple with an interior surface
and an exterior stirface and a first end and a second end, said
nipple interconnected at its second end to said wall around said
aperture with said first end of said nipple extending outwardly
frown said wall, and having a barrel flange interconnected to said
barrel at said second end thereof and extending outwardly from said
exterior surface of said barrel;
a plunger assembly extending into the interior of said barrel in
telescoping relation therewith through said second end of said barrel,
including an elongate hollow tubular plunger body with an interior
surface and an exterior surface, a longitudinal axis, a closed first
end disposed in the interior of said barrel, and a second end extending
outwardly from said second end of said barrel, said plunger body
having an elongate narrow slot extending from said first end of
said plunger body toward said second end through the majority of
the length of said plunger body, said slot having a longitudinal
axis parallel to said longitudinal axis of said plunger body, and
said plunger body having a plunger opening extending through said
first end in coaxial alignment with said longitudinal axis of said
plunger body, including a plunger flange interconnected to said
second end of said plunger body, said plunger flange extending across
said second end of said plunger body and extending outwardly therefrom,
including needle retraction locking means interconnected to said
interior surface of said plunger body near said second end thereof
to engage a needle assembly disposed in said plunger body, and including
a plunger piston having a piston opening extending therethrough,
said plunger piston interconnected to said first end of said plunger
body with said piston opening coaxially aligned with and in communication
with said plunger opening, said plunger piston in fluid tight sliding
relation with said interior surface of said barrel;
a needle assembly including an elongate thin hollow tubular needle
greater in length than said barrel, said needle having an interior
surface and an exterior surface, an open first end and a second
end, and a longitudinal axis, said needle disposed partially in
said plunger body with said first end of said needle extending through
said plunger opening and said piston opening of said plunger assembly
and outwardly therefrom in coaxial alignment therewith, and said
needle having a needle port extending from said interior surface
to said exterior surface to form a passageway from the interior
of said needle to the exterior thereof disposed between said first
and second ends of said needle, and a needle head interconnected
to said second end of said needle and disposed in said plunger body,
and said needle head having a lever arm interconnected to and extending
outwardly from said needle head and through said slot of said plunger
body with said lever arm generally perpendicular to said longitudinal
axis of said needle, said lever arm including lever latching means
to be selectively engaged with said barrel flange of said barrel;
a plunger needle seal means disposed in said piston opening of
said plunger piston around said needle of said needle assembly to
form a fluid tight seal between said plunger piston and said needle;
and
a barrel needle seal means disposed at said first end of said barrel
assembly around said needle of said needle assembly to form a fluid
tight seal between said barrel assembly and said needle.
2. The apparatus of claim 1 wherein said plunger needle seal means
comprises an o'ring seat concentrically disposed within said piston
opening of said plunger piston and an o'ring disposed within said
o'ring seat such that said o'ring forms said fluid tight seal between
said plunger assembly and said needle.
3. The apparatus of claim 1 wherein said plunger needle seal means
comprises an o'ring positioned between said first end of said plunger
assembly and said plunger piston such that said o'ring forms said
fluid tight seal between said plunger assembly and said needle.
4. The apparatus of claim 1 wherein said plunger needle seal means
comprises an o'ring concentrically disposed within said piston opening
of said plunger piston, said o'ring being molded as a part of said
plunger piston such that said o'ring forms said fluid tight seal
between said plunger assembly and said needle.
5. The apparatus of claim 1 wherein said plunger needle seal means
comprises a packing gland positioned within said piston opening
and extending into said plunger opening with said packing gland
restrained by said piston, said packing gland having an aperture
in coaxial alignment with said longitudinal axis of said plunger
body to receive said needle therethrough such that said packing
gland forms said fluid tight seal between said plunger assembly
and said needle.
6. The apparatus of claim 1 wherein said plunger needle seal means
comprises a microfilter positioned within said piston opening and
extending into said plunger opening with said microfilter restrained
by said piston, said microfilter having an aperture in coaxial alignment
with said longitudinal axis of said plunger body to receive said
needle therethrough such that said microfilter forms said fluid
tight seal between said plunger assembly and said needle.
7. The apparatus of claim 1 adapted to allow the flow of gas between
said needle and said plunger piston and between said plunger piston
and said plunger body when said plunger assembly is at rest within
said barrel and to prevent such flow of gas when said plunger assembly
is moving relative to said barrel, when said barrel is free of liquid,
and to seal against such flow of gas when said barrel is filled
with liquid between said first end of said barrel and said first
end of said plunger assembly,
wherein said plunger body further includes a plunger lip interconnected
to and disposed outwardly from said first end of said plunger body
around said plunger opening:
wherein said plunger piston extends over and is loosely connected
to said plunger lip in coaxial relation therewith;
wherein said plunger lip includes an o'ring seat concentrically
disposed within said piston opening and an o'ring disposed within
said o'ring seat and against said needle so as to form said fluid
tight seal between said plunger assembly and said needle:
wherein said plunger piston includes a plurality of piston spacers
formed on and extending longitudinally outward from said second
end of said plunger piston between said plunger piston and said
first end of said plunger body around said plunger opening:
and wherein said plunger piston further includes a microfilter
positioned and loosely retained within said conduit in said plunger
piston with said microfilter in a dry condition, said microfilter
having an aperture through which said needle extends in sealing
relation with said microfilter, said microfilter expanding upon
contact with liquid so as to become imperious to the flow of gaseous
and liquid fluids therethrough and expand to close said piston opening
between said plunger piston and said needle and form a fluid tight
seal between said plunger piston and said needle within said piston
opening.
8. The apparatus of claim 1 wherein said barrel seal means comprises
an o'ring seat concentrically disposed within said interior surface
of said nipple and an o'ring disposed within said o'ring seat such
that said o'ring forms said fluid tight seal between said barrel
assembly and said needle.
9. The apparatus of claim 2 wherein said barrel assembly further
comprises an open ended annular conduit with an interior surface
and an exterior surface and with a first end and a second end, said
conduit being of larger cross-sectional diameter than said nipple
of said hollow tubular barrel, said conduit interconnected at its
second end to said wall of said hollow tubular barrel concentric
with said nipple of said hollow tubular panel and extending outwardly
from said wall of said hollow tubular barrel, and said conduit having
screw threads formed on the interior surface thereof.
10. The apparatus of claim 9 further comprising a barrel cap having
a first end, a second end, an outer surface, and a conduit extending
through said barrel cap from said first end to said second end to
receive said needle therethrough, forming an interior surface of
said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, wherein said barrel seal means comprises an
o'ring positioned between said first end of said nipple and said
barrel cap assembly to form a fluid tight seal against said needle.
11. The apparatus of claim 9 further comprising a barrel cap having
a first end a second end, an outer surface, and a conduit extending
through said barrel cap from said first end to said second end to
receive said needle therethrough, forming an interior surface of
said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel can being generally
of conical configuration with said second end of larger diameter
than said first end, and further having an o'ring seat concentrically
disposed within said interior surface of said first end of said
barrel cap, wherein said barrel seal means comprises a resealable
rubber gasket positioned between said first end of said nipple and
said barrel cap such that said resealable rubber gasket forms a
first liquid tight seal against said needle when said needle is
in a first position extended through said gasket; and such that
said resealable rubber gasket reseals when said needle is in a second
position retracted from said gasket; and an o'ring disposed within
said o'ring seat such that said o' ring forms a second fluid tight
seal against said needle when said needle is in said first, extended,
position.
12. The apparatus of claim 9 further comprising a barrel cap having
a first end, a second end, an outer surface, and a conduit extending
through said barrel cap from said first end to said second end to
receive said needle therethrough, forming an interior surface of
said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel can being generally
of conical configuration with said second end of larger diameter
than said first end, and having an o'ring seat positioned within
said interior surface of said first end of said barrel cap, wherein
said barrel seal means comprises an o'ring positioned within said
o'ring seat such that said o'ring forms a fluid tight seal against
and said needle.
13. The apparatus of claim 9 further comprising a barrel cap having
a first end, a second end, an outer surface, and a conduit extending
through said barrel cap from said first end to said second end to
receive said needle therethrough, forming an interior surface of
said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, wherein said barrel seal means comprises a
needle guide being axially arranged within said interior surface
of said barrel cap about said extended longitudinal axis further
having a first end and a second end and having an interior surface
and an exterior surface, said second end having a radial ridge positioned
on said exterior surface, said second end of said needle guide being
near said conical tip of said tubular elongated barrel, and further
having a resealable rubber gasket said resealable rubber gasket
being positioned over said second end of said needle guide and catching
over said ridge on said needle guide such that said resealable rubber
gasket forms a liquid tight seal against said needle when said needle
is in a first position extended through said gasket, and such that
said resealable rubber gasket reseals when said needle is in a second
position retracted from said gasket,
14. The syringe and needle apparatus of claim 1 wherein said plunger
flange includes a flange opening extending therethrough in coaxial
alignment with said longitudinal axis of said plunger body, wherein
said needle head includes a head axial opening extending therethrough
in coaxial alignment with said needle and in communication with
the hollow interior of said needle, and wherein the syringe and
needle apparatus further comprises a needle guide wire/valve assembly
including a guide wire/valve head interconnected within said flange
opening of said plunger flange, and an elongate wire having a longitudinal
axis, a first end, and a second end, interconnected at its second
end to said guide wire/valve head in coaxial alignment with said
plunger body, extending through said head axial opening of said
needle head and into the hollow interior of said needle in a fluid
tight sliding relation therewith.
15. The apparatus of claim 14 wherein said plunger needle seal
means comprises an o'ring seat concentrically disposed within said
piston opening of said plunger piston and an o'ring disposed within
said o'ring seat such that said o'ring forms said fluid tight seal
between said plunger assembly and said needle.
16. The apparatus of claim 14 wherein said plunger needle seal
means comprises an o'ring disposed between said first end of said
plunger assembly and said plunger piston such that said o'ring forms
said fluid tight seal between said plunger assembly and said needle.
17. The apparatus of claim 14 wherein said plunger needle seal
means comprises an o'ring concentrically disposed within said piston
opening of said plunger piston said o'ring being molded as a part
of said plunger piston such that said o'ring forms said fluid tight
seal between said plunger assembly and said needle.
18. The apparatus of claim 14 wherein said plunger needle seal
means comprises a packing gland positioned within said piston opening
and extending into said plunger opening with said packing gland
restrained by said piston, said packing gland having an aperture
in coaxial alignment with said longitudinal axis of said plunger
body to receive said needle therethrough such that said packing
gland forms said fluid tight seal between said plunger assembly
and said needle.
19. The apparatus of claim 14 wherein said plunger needle seal
means comprises a microfilter positioned within said piston opening
and extending into said plunger opening with said microfilter restrained
by said piston, said microfilter having an aperture in coaxial alignment
with said longitudinal axis of said plunger body to receive said
needle therethrough such that said microfilter forms said fluid
tight seal between said plunger assembly and said needle.
20. The apparatus of claim 14 adapted to allow the flow of gas
between said needle and said plunger piston and between said plunger
piston and said plunger body when said plunger assembly is at rest
within said barrel and to prevent such flow of gas when said plunger
assembly is moving relative to said barrel, when said barrel is
free of liquid, and to seal against such flow of gas when said barrel
is filled with liquid between, said first end of said barrel and
said first end of said plunger assembly,
wherein said plunger body further includes a plunger lip interconnected
to and disposed outwardly frown said first end of said plunger body
around said plunger opening;
wherein said plunger piston extends over and is loosely connected
to said plunger lip in coaxial relation therewith;
wherein said plunger lip includes an o'ring seat concentrically
disposed within said piston opening and an o'ring disposed within
said o'ring seat and against said needle so as to form said fluid
tight seal between said plunger assembly and said needle;
wherein said plunger piston includes a plurality of piston spacers
formed on and extending longitudinally outward from said second
end of said plunger piston between said plunger piston and said
first end of said plunger body around said plunger opening;
and wherein said plunger piston further includes a microfilter
positioned and loosely retained within said conduit in said plunger
piston with said microfilter in a dry condition, said microfilter
having an aperture through which said needle extends in sealing
relation with said microfilter, said microfilter expanding upon
contact with liquid so, as to become impervious to the flow of gaseous
and liquid fluids therethrough and expand to clause said piston
opening between said plunger piston and said needle and form a fluid
tight seal between said plunger piston and said needle within said
piston opening.
21. The apparatus of claim 14 wherein said barrel seal means comprises
an o'ring seat concentrically disposed within said interior surface
of said conical nipple and an o'ring disposed within said o'ring
seat such that said o'ring forms said fluid tight seal between said
barrel assembly and said needle.
22. The apparatus of claim 14 wherein said barrel assembly further
comprises an open ended annular conduit with an interior surface
and an exterior surface and with a first end and a second end, said
conduit being of larger cross-sectional diameter that said nipple
of said hollow tubular barrel, said conduit interconnected at its
second end to said wall of said hollow tubular barrel concentric
with said nipple of said hollow tubular barrel and extending outwardly
from said wall of said hollow tubular barrel, and said conduit having
screw threads formed on the interior surface thereof.
23. The apparatus of claim 22 further comprising a barrel cap
having a first end, a second end, an outer surface, and a conduit
extending through said barrel cap from said first end to said second
end to receive said needle therethrough, forming an interior surface
of said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, wherein said barrel seal means comprises an
o'ring positioned between said first end of said nipple and said
barrel cap assembly to form a fluid tight seal against said needle.
24. The apparatus of claim 22 further comprising a barrel cap
having a first end, a second end, an outer surface, and a conduit
extending through said barrel cap from said first end to said second
end to receive said needle therethrough, forming an interior surface
of said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, and further having an o'ring seat concentrically
disposed within said interior surface of said first end of said
barrel cap, wherein said barrel seal means comprises a resealable
rubber gasket positioned between said first end of said nipple and
said barrel cap such that said resealable rubber gasket forms a
first liquid tight seal against said needle when said needle is
in a first position extending through said gasket; and such that
said resealable rubber gasket reseals when said needle is in a second
position retracted from said gasket; and an o'ring disposed within
said o'ring seat such that said o' ring forms a second fluid tight
seal against said needle when said needle is in said first, extended,
position.
25. The apparatus of claim 22 further comprising a barrel cap
having a first end, a second end, an outer surface, and a conduit
extending through said barrel cap frown said first end to said second
end to receive said needle therethrough, forming an interior surface
of said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, wherein said barrel seal means comprises a
packing gland positioned between said first end of said nipple and
said barrel cap, said packing gland being restrained by said barrel
cap, said packing gland having an aperture coaxially aligned with
said longitudinal axis of said barrel, such that said packing gland
forms a fluid tight seal against said needle.
26. The apparatus of claim 22 further comprising a barrel cap
having a first end, a second end, an outer surface, and a conduit
extending through said barrel cap from said first end to said second
end to receive said needle therethrough, forming an interior surface
of said barrel cap, said second end of said barrel cap having lugs
to engage said screw threads on said interior surface of said conduit
of said tubular elongated barrel, said barrel cap being generally
of conical configuration with said second end of larger diameter
than said first end, said first end of said barrel cap further having
a radial groove arranged about said exterior surface, said barrel
cap further having a needle guide being axially arranged within
said interior surface of said barrel cap about said extended longitudinal
axis, wherein said barrel seal means comprises a resealable rubber
gasket placed over said first end of said barrel cap and catching
within said groove on said barrel cap such that said resealable
rubber gasket forms a liquid tight seal against said needle when
said needle is in a first position extended through said gasket,
and such that said resealable rubber gasket reseals when said needle
is in a second position retracted from said gasket.
27. A Method of using a safety syringe to inject a fluid into a
subject, the safety syringe having a first position with its needle
extended and a second position having its needle retracted and having
a lever arm, a lever arm latch, retraction locking ramps, a barrel
assembly having a barrel flange and a hollow barrel and having a
plunger assembly disposed within the hollow barrel, defining a variable
volume fluid holding portion of the barrel comprising:
(a) filling the fluid holding portion of the barrel with fluid;
(b) inserting the needle into the subject to receive the fluid;
(c) moving the plunger to reduce the volume of the fluid holding
portion of the barrel such that the fluid transfers into the subject;
(d) withdrawing the needle from the subject;
(e) rotating the needle arm such that the lever arm latch clears
the barrel flange;
(f) pulling on the needle an such that the lever arm slides upward
within the plunger;
(g) clicking the needle head into the retraction locking ramps
so that the needle is locked in its retracted position fully disposed
within the plunger.
28. A Method of using a safety syringe to inject a fluid into a
subject, the safety syringe having a first position with its needle
extended and a second position having its needle retracted and having
a lever arm, a lever arm latch, retraction locking ramps, a barrel
assembly having a barrel flange and a hollow barrel and having a
plunger assembly disposed within the hollow barrel, defining a variable
volume fluid holding portion of the barrel and further having a
needle port in the needle and a needle guide wire/valve within the
needle comprising:
(a) filling the fluid holding portion of the barrel with fluid;
(b) inserting the needle into the subject to receive the fluid;
(c) moving the plunger to reduce the volume of the fluid holding
portion of the barrel such that the fluid transfers into the subject;
(d) withdrawing the needle from the subject;
(e) rotating the needle an such that the lever arm latch clears
the barrel flange;
(f) pulling on the needle arm such that the lever arm slides upward
within the plunger whilst the needle guide wire/valve remains stationary
so that the needle port is sealed closed by the needle guide wire/valve;
(g) clicking the needle head into the retraction locking ramps
so that the needle is locked in its retracted position fully disposed
within the plunger.
29. A Method of using a safety syringe to sample a fluid from a
subject by pressure, the safety syringe having a first position
with its needle extended and a second position having its needle
retracted and having a lever arm, a lever arm latch, retraction
locking ramps, a barrel assembly having a barrel flange and a hollow
barrel and having a plunger assembly disposed within the hollow
barrel, defining a variable volume fluid holding portion of the
barrel and further having a needle port in the needle and a needle
guide wire/valve within the needle comprising:
(a) retracting the plunger to a preselected position within the
barrel to set the required sample volume;
(b) inserting the needle into the subject from which the fluid
sample is to be drawn;
(c) allowing the fluid sample to enter the barrel assembly whilst
allowing any entrained air to escape from the barrel;
(d) withdrawing the needle from the subject;
(e) rotating the needle arm such that the lever arm latch clears
the barrel flange;
(f) pulling on the needle arm such that the lever arm slides upward
within the plunger whilst the needle guide wire/valve remains stationary
so that the needle port is sealed closed by the needle guide wire/valve;
(g) clicking the needle head into the retraction locking ramps
so that the needle is locked in its retracted position fully disposed
within the plunger;
(h) taking the enclosed sample to a processing station;
(i) expelling the sample by pushing on the plunger.
30. A Method of using a safety syringe to sample a fluid frown
a subject by aspiration, the safety syringe having a first position
with its needle extended and a second position having its needle
retracted and having a lever arm, a lever arm latch, retraction
locking ramps, a barrel assembly having a barrel flange and a hollow
barrel and having a plunger assembly disposed within the hollow
barrel, defining a variable volume fluid holding portion of the
barrel and further having a needle port in the needle and a needle
guide wire/valve within the needle comprising:
(a) inserting the needle into the subject from which the fluid
sample is to be drawn;
(b) retracting the plunger to a given position within the barrel
to see the required sample volume;
(c) withdrawing the needle from the subject;
(d) rotating the needle arm such that the lever arm latch clears
the barrel flange;
(e) pulling on the needle arm such that the lever arm slides upward
within the plunger whilst the needle guide wire/valve remains stationary
so that the needle port is sealed closed by the needle guide wire/valve;
(f) clicking the needle head into the retraction locking ramps
so that the needle is locked in its retracted position fully disposed
within the plunger;
(g) taking the enclosed sample to a processing station;
(h) expelling the sample by pushing on the plunger.
Safety syringe description
TECHNICAL FIELD OF THE INVENTION
This invention relates to hypodermic syringes and their use in
Arterial Blood Gas Analysis. In particular it relates to a syringe
that will safely sheath the needle after drawing blood to protect
a worker and still allow the syringe to inject its sample into an
Arterial Blood Gas Analysis Machine with the needle sheathed. The
device could easily find use as a regular hypodermic syringe containing
an easily sheathed needle.
BACKGROUND OF THE INVENTION
Hypodermic syringes have been used in medicine for countless years.
They find use for the injection of fluids into the body and for
the removal of sample fluids from the body. Most syringes have a
common business end in the form of a sharp needle. For as long as
syringes have been used, countless medical workers have been accidently
picked by an exposed needle. An accidental pricking causes little
harm if and only if the needle has not been contaminated by being
inserted into a body otherwise the needle would still be sterile
(i.e. no germs, no bacteria, no virus, etc. will be present on the
needle). The major concern occurs if the accidental pricking of
the medical worker occurs after the needle has been inserted into
a body. Today's major dread is exposure to HIV, although exposure
to Hepatitis B should not be overlooked.
There have been many efforts by previous medical workers to devise
a safe and certain method for sheathing a needle after its use and
before the syringe has been properly disposed. These methods or
inventions have taken two avenues:
1) an external sliding sheath that covers the needle, and
2) a system to retract the needle into the body of the syringe.
The simplest devices have been those that externally sheath the
needle while the most complex have been those that retract the used
needle. All of these safety devices must have a positive locking
device to either keep the guard (or sheath) in place or keep the
retracted needle in place within the body of the syringe.
Generally the sheathing devices use an external catch or tab molded
onto the outside of the syringe body. This results in a distortion
of the circular shape of the syringe and makes it almost impossible
to insert into another instrument, such as a Blood Gas Analysis
Machine, so the body sample contained within the syringe can be
safely and hygienically injected into that instrument. Generally
speaking, in these externally guarded syringes the sheath must be
withdrawn to allow re-injection of the sample; thus the worker is
again exposed to a prickly potential.
The devices which use a retractable needle generally accomplish
their purpose by using a loaded spring and latches within the syringe.
Thus after the syringe is used, the plunger is pushed harder or
a latch is pressed and the needle "shoots" back inside
the syringe body. This technique appears to work in spite of the
number of parts and the potential for an unwanted retraction. Unfortunately
if these devices were to be used for Blood Gas Analysis or any analysis
that requires the taking of a body sample for re-injection into
a machine, the retracted needle will interfere with the release
of the sample. That is, with the needle firmly wedged inside the
body of the syringe, the plunger cannot move back into the body
of the syringe and force the sample out of the syringe.
An object of this invention is to make available a safety syringe
in which the needle can be retracted into the body of the syringe
after use and yet not interfere with the operation of the syringe
when it is used to collect body samples; yet be capable of regular
use. Another object of the invention was to provide a syringe that
was easy to manufacture and did not use a loaded spring to retract
the needle; thus making accidental retraction impossible. Furthermore,
the syringe becomes perfectly safe after needle retraction and cannot
accidently prick a worker in the laboratory when a body sample is
being injected into an analysis machine. In addition, by using a
retractable needle, the syringe retains its standard circular shape
and will fit into any of the standard laboratory analysis machines.
Finally, because the actual needle retracts out of the way, "the
nipple" of the syringe is safely available for attachment to
analysis machines--this is the preferred method of attachment to
such machines.
PRIOR ART
Examples of safety syringes that use external sheathing can be
found in U.S. Pat. Nos. 4681567; 4738663; 5019051; and 5088896
and in European Patent Application 0369619. This form of the prior
art will be the first to be examined.
U.S. Pat. No. 4681567 (Masters et al.) discloses a cumbersome
external sheath or guard. The sheath guide mechanism distorts the
circular outside of the syringe body in such a manner that it would
be impossible to insert the syringe into a laboratory analysis machine.
The only way to use this device would be to unsheathe the needle,
which is very easy, and inject fluid via the needle. The exposed
needle would offer a serious prickly potential the medical worker
or technician.
U.S. Pat. No. 4738663 (Bogan) is an "improvement" on
Masters in that the sheathed needle cannot readily be exposed. This
disclosure works well for a standard hypodermic syringe which is
used ONLY to give injections but will not work well for sample syringes
in that the sheath will interfere with an analysis machine. Furthermore,
since the sheath cannot be retracted the syringe really cannot be
used as a sample syringe or collection device.
U.S. Pat. No. 5019051 (Hake) is another variation of the external
sheath guard concept. Here again the external sheath would interfere
with an analysis machine whenever the sample was re-injected. U.S.
Pat. No. 5088986 (Nusbaum) discloses a spring loaded slidable
sheath. Its external locking tabs greatly distort the tube-like
structure of the syringe body and would interfere with any analysis
machine. The device could be used with an analysis machine but only
if the needle were re-exposed. Thus the worker could again be exposed
to a prickly potential.
In a similar manner, the European Disclosure 0369619 (Ogie &
Braddock), would interfere with the analysis machine. Once more
this disclosure can re-expose the needle to the laboratory worker
with the corresponding prickly potential.
Examples of needle retraction devices can be found in U.S. Pat.
Nos. 4834718; 4932945; 4946446; 4973316; 5032117; 5092853;
and 5114410 and in British Patent 2243552A. We will now examine
this type of protection.
U.S. Pat. No. 4834718 (McDonald) discloses a retractable needle
and catheter system. The retractable needle operates in conjunction
with a catheter and is meant to puncture the skin to allow the catheter
to enter a body. Once the catheter is in place the needle is withdrawn
into the device and the needle/sheath device is disengaged from
the catheter. This leaves the catheter in place and the puncture
device in a safe state. It is absolutely impossible for this disclosure
to act as a syringe for it can neither inject fluids nor withdraw
fluids.
U.S. Pat. No. 4932945 (Braginetz et al.) also discloses a catheter
insertion device with a retractable needle. This disclosure is similar
to that of McDonald but adds a self sealing bushing to prevent back-flow
of body fluids into the insertion housing. The insertion needle
punctures the bushing and passes though the catheter housing, upon
withdrawal of the needle the bushing closes off to stop any fluids
from moving into the needle housing (see claim 10).
U.S. Pat. No. 4946446 (Vadher) discloses a spring loaded needle
retraction system. The needle retraction system actually is a needle
and spring loaded retraction sheath that attaches to a regular syringe
via the "Luer-Lock" or nipple. Essentially the device
works somewhat like the retraction mechanism in a ballpoint pen.
There is a rotational cam which holds the needle extended while
the shot is administered; upon twisting the plunger to one side
the cam rotates and the needle is automatically retracted into the
housing, The device can be used to draw blood for Blood Gas Analysis
machines, but suffers from the fact that the syringe cannot be shut
off from the atmosphere. Thus the blood sample can be contaminated
or outgas while the sample is being transported to the laboratory.
Outgas is a term of art that means that the sample will allow entrained
gases to be released, thus the sample will no longer contain the
same volume of gases as when the sample was first taken; whereas
contamination would that the sample would absorb gases from the
atmosphere. Another drawback is that the needle system when attached
to a syringe will be inordinately long and difficult to use.
U.S. Pat. No. 4973316 (Dysarz) claims to have produced a safety
retractable needle injection syringe. When the chamber which holds
the injection fluid is full the needle cannot be retracted. Thus
if this device is used to obtain samples then the needle must be
left exposed. Hence, this device does not provide any protection
to the worker in the laboratory.
U.S. Pat. No. 5032117 (Motta) appears to use a sheathed needle
but the function of this needle is only to vent a gravity feed intravenous
delivery system after a measured dose of medication had been delivered
by syringe.
U.S. Pat. No. 5092853 (Couvertier) discloses yet another spring
loaded needle retraction system. The stated purpose of this device
is to permanently store the needle after use to protect the medical
worker and to prevent further use of the syringe by unauthorized
users such as illegal drug addicts. Thus this system is deliberately
designed NOT to be used other than as a one time hypodermic syringe.
The device cannot be used as a sample syringe. Further the spring/needle
latching system causes a distortion of the body of the syringe as
that it would be difficult to use in an analysis machine.
U.S. Pat. No. 5114410 (Caralt Batlie) discloses a further spring
loaded needle retraction system. This disclosure is simpler then
the Couvertier syringe and does not distort the outer body of the
syringe but when the needle is retracted it is once again impossible
to reuse the syringe. This device cannot be used for taking blood
samples.
U.K. Patent Application 2243552A (Deighton et al.) discloses
one more version of a spring loaded needle retraction system. In
this disclosure the needle is manufactured with a slight bend so
that when the needle is retracted, after use, the needle cannot
possibly be forced out by pressure on the plunger. Thus this system
cannot be used for sample collection use as the stored sample could
not be ejected.
It is very apparent that the prior art has not considered the use
of "safety" syringes for use as a body fluids sample collector,
be they the sheathing type or the retraction type. The sheathing
devices could possibly work as sample collectors but fail to protect
the needle when the sample is being discharged for analysis. The
spring loaded retraction systems do not lend themselves to a sample
syringe and they suffer from extreme complexity. One further disadvantage
for the spring loaded systems is the possible failure of the latch
during use which would retract the needle at the wrong time. The
instant invention solves all the problems contained within the prior
art and solves problems not envisioned by the prior art
SUMMARY OF THE INVENTION
The instant invention is a simple safety syringe utilizing a retractable
needle which is stored within the plunger of the syringe. The instant
invention may be used as a standard hypodermic syringe or as a sample
syringe. The needle retraction system is "on-call", that
is to say the user manually retracts the needle into the plunger
housing alter using the syringe. There is absolutely no fear of
an accidental retraction of the needle while the syringe is in use.
The preferred embodiment does not envision reuse of the needle once
it is retracted but there is no reason why the device could not
be set up to be reusable. For example the syringe could be sent
to the user with the needle retracted, the user could extend the
needle, the user could employ the device, and then the user could
finally retract the used needle.
In order to facilitate the summary of the invention, the simplest
embodiment of the invention will be described. The simplest embodiment
is the hypodermic injection syringe which for all practical purposes
starts with the standard hypodermic barrel; complete with a standard
Luer Lock. The plunger of the syringe is modified so that it is
a hollow plunger with a slot running its entire length. The retractable
needle, which is roughly the same length as the plunger runs through
the hollow plunger and out of the end of both the plunger and the
barrel of the syringe. The end of the needle that is within the
plunger is terminated with a head or cap that has a lever arm that
extends out of the slot on the plunger. The hollow needle has a
port that would be in communication with the inside of the syringe
barrel. The port is positioned so that it is at the extreme bottom
(nearest the exposed needle) end of the barrel. This ensures that
as the plunger is depressed the fluid in the body would be forced
into and through the hollow needle. This of course assumes that
the proper seals are in place around the hollow needle and the plunger/piston
as well as the barrel nipple and the hollow needle. These sealing
arrangements will be discussed.
To keep the retractable needle extended, the lever arm has a latch
which can lock over the barrel finger flange. In the extended position,
the lever arm latch slides over the barrel flange and keeps the
needle extended. The lever arm is free to move within the slot in
the plunger and vice versa. Since the plunger is free to rotate
within the barrel the lever arm can also rotate. In order to unlatch
the needle for retraction, the lever arm is rotated so that the
lever arm latch disengages from the barrel finger flange. Note that
the barrel finger flange can be manufactured with a slot so that
the lever arm latch can clear the flange or the standard syringe
that incorporates a flange with two flat sides can be used. If the
standard syringe flange incorporating two flat sides is used, the
lever arm latch will clear the flange in two places (i.e. the two
flats). Once the lever arm latch clears the flange, the lever arm
can be moved "upwards" withdrawing the needle into the
hollow plunger. The hollow plunger is formed with latching ramps
at the top end of the plunger. When the needle head reaches the
top of the hollow plunger, the latching ramps will retain the needle
head and the needle remains up inside the hollow plunger. The plunger
can be pushed down towards the bottom of the syringe barrel, but
the needle will not come out because the needle is inside the hollow
plunger. Actually, the retracted needle will extend slightly below
the piston and into the nipple of the barrel whenever the plunger
is completely pushed down towards the bottom of the syringe barrel.
Note, the retracted needle will not extend out of the barrel nipple
when the plunger is completely pushed down.
This simplified explanation describes one embodiment of the device
which envisions the injection hypodermic syringe. When the invention
is used as an aspiration sampler, as the plunger is withdrawn, sample
fluid would be drawn through the needle and into the barrel. Finally,
if the syringe is used as a pressure filled sampler and with the
plunger withdrawn to the required sample volume, arterial blood
pressure will force the sample into the hollow needle, through the
needle port and into the barrel interior. The operation is absolutely
the same as a standard syringe or as a standard combined aspirator/pressure
sampler. However, when the hypodermic embodiment is used as a sample
collector several problems can occur. First, sample fluid can escape
through the open end of the barrel at the Luer Lock when the needle
is retracted. Second, fluid can pass through the hollow needle and
through the .needle port into the plunger and then out of the syringe
when the needle is retracted. A second embodiment of the invention
solves these problems by adding a seal at the barrel Luer Lock end
of the syringe, a valve to close off the needle port when the needle
is retracted, and a seal between the hollow plunger and the hollow
needle. The barrel Luer Lock end seal may take one of two forms:
the seal can be incorporated into the barrel or the seal can be
incorporated into a cap that fits into the Luer Lock. The second
method is preferred for it means that a standard unmodified syringe
barrel may be used, whereas the first method would require another
manufacturing step. The needle port valve consists of a solid wire
affixed the plunger and over which the hollow needle retracts. As
the needle is retracted, the wire stays in place and forces fluid
back along the hollow needle, out the port and into the barrel.
Eventually the wire passes the needle port effectively blocking
the port. This valve system ensures that the sample cannot be contaminated
nor can gases contained within the sample outgas. The syringe becomes
a completely closed sample vessel: a factor that is critical in
Arterial Blood Gas Analysis.
It should also be apparent that a seal arrangement, in all embodiments,
will be needed between the hollow needle and the tip of the hollow
plunger. This seal can take one of several forms. For example if
the device is being used as a pressure filled sampler, then the
seal must allow air within the syringe barrel to escape; however,
that seal must then stop any fluid from passing. This can be accomplished
using a "microfilter" material which is well known in
the art. The microfilter will pass air, but when fluid touches the
filter it expands and seals. On the other hand if the instant invention
is used as an injection syringe or as an aspirator sampler, the
seal must be tight at all times. This can be accomplished with the
use of proper seals within the hollow plunger or piston. A similar
seal arrangement will be needed at the Luer Lock end of the barrel.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of the instant invention showing the
preferred embodiment.
FIG. 2 is an enlarged exploded view showing generally the needle
guide wire/valve assembly and the needle assembly.
FIG. 3 is an enlarged view of the assembled hollow needle and guide
wire/valve assembly.
FIG. 4 is an enlarged exploded view of the hollow plunger assembly.
FIG. 5 is a ghost view of the Needle Retraction System, which includes
the needle and guide wire/valve assembly, the needle assembly and
the plunger assembly.
FIG. 5A is a ghost view of an Alternate Embodiment for standard
injections and includes only the needle assembly and the `capped`
plunger assembly.
FIG. 5B is an enlarged view of the needle port showing the needle
valve closing off the needle port shown in FIG. 5.
FIG. 6 is an exploded view of a standard barrel assembly showing
the finger flange and flat spots on that flange.
FIG. 6A is all exploded view of an alternate embodiment of a barrel
assembly showing the finger flange and the `pass slot` in that flange.
FIG. 7A is a side view of the Pressure Mode Barrel Needle Seal
System.
FIG. 7G is an enlarged view of the barrel needle seal system shown
in FIG. 7A.
FIG. 7B is a side view of the Aspiration Mode Barrel Needle Seal
System.
FIG. 7H is an enlarged view of the barrel needle seal system shown
in FIG. 7B.
FIG. 7C is a side view of the Injection Mode Barrel Needle Seal
System.
FIG. 7I is an enlarged view of the barrel needle seal system shown
in FIG. 7C.
FIG. 7D is a side view of an alternate embodiment of the Barrel
Needle Seal System which would function in all modes.
FIG. 7J is an enlarged view of the barrel needle seal system shown
in FIG. 7D.
FIG. 7E is a side view of another alternate Barrel Needle Seal
System in which the seal is placed in the barrel of the syringe.
Note that a similar seal arrangement could be used to seal the needle
in the plunger.
FIG. 7K is an enlarged view of the barrel needle seal system shown
in FIG. 7E.
FIG. 7F is a side view of yet another alternate Barrel Needle Seal
System in which the seal is placed in the barrel nipple and held
in place by a modified Luer Cap.
FIG. 7L is an enlarged view of the barrel needle seal system shown
in FIG. 7F.
FIG. 8A is a side view of the assembled invention showing the needle
extended and locked in place. The plunger is shown in the fully
in position.
FIG. 8B is a side view of the assembled invention, rotated 90.degree.
about its axis, showing the needle extended and locked in place.
The plunger is shown in the withdrawn position as if the syringe
were being used as a pressure sampler.
FIG. 8C shows the needle retracted and locked in place inside the
hollow plunger.
FIG. 8D shows the needle retracted and plunger pushed back into
the barrel. This figure illustrates the expulsion of a sample into
a Blood Gas Analysis Machine. Note how the retracted needle remains
within the confines of the barrel and yet does not interfere with
plunger motion.
FIG. 9 is a side view of a seal arrangement between the hollow
plunger plunger and the hollow needle. This arrangement shows a
standard plunger piston modified for use on the hollow plunger:
the standard plunger piston shown here will operate in both pressure
filled and aspiration samplers. The o'ring seal can similarly be
used in the injection mode. Although not shown, the piston could
be further modified to retain the o'ring without using a molded
lip.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
There are several preferred embodiments within the instant invention
and the preference depends to a great extent on manufacturing and
sales choices. The instant invention can be supplied in one of three
major forms:
A) hypodermic injection syringe, or
B) hypodermic sampling syringe of two forms:
B1) aspiration filling, which could also inject, or
B2) pressure filling, which could not inject.
There are also several variations for the syringe barrel tip which
interact with the three major embodiments and which in themselves
increase the overall number of preferred embodiments. There is an
alternate syringe barrel design. Finally there are several alternate
designs for sealing the retractable hollow needle at the barrel
tip and within the hollow plunger. The major embodiments will be
discussed in reverse order.
Attention is called to FIGS. 1 through 8 which show the preferred
pressure sampler embodiment of the safety syringe. These figures
also :illustrate a number of the alternative designs which will
be discussed in due course. The safety pressure sampler embodiment
consists of 10 interrelated parts:
the guide wire/valve assembly (shown generally as 11),
the needle assembly (shown generally as 12),
the plunger assembly (shown generally as 14),
the barrel assembly (shown generally as 15), and
the barrel cap assembly (shown generally as 16).
The operation of the needle guide wire/valve assembly will be explained
first. Referring to FIG. 2 the guide wire/valve assembly (generally
11 ) consists of a guide wire (2) with a cap (1). The guide is sized
so that it just fits inside the hollow needle (4) but yet slides
easily inside the hollow needle. The hollow needle assembly (generally
12) consists of a needle head (3) with a lever arm (20) and a lever
arm latch (21) formed within the lever arm (20). The needle head
(3) is attached to the hollow needle (4) and contains an axial opening
which aligns with the inside of the hollow needle (4) thus allowing
the guide wire (2) to pass through the needle head (3) and into
the hollow needle (4). The hollow needle (4) contains a port (22)
which is positioned on the hollow needle (4) so that when the needle
is fully extended then the port (22) is near or at the bottom of
the inside of the syringe barrel. (See FIG. 7.) The hollow needle
(4) terminates at its distal end in the standard needle bevel or
point (33). Retraction of this point (33) is the purpose of this
instant invention.
The guide wire (2) actually serves as a valve and closes off the
needle port (22) whenever the wire passes down the needle towards
the beveled end (or point) when the hollow needle is retracted.
The needle assembly, for the pressure (or even aspirator) sampler,
is shown assembled in FIG. 3 (generally 13). Since the guide wire
(2) is designed to barely fit within the hollow needle (4), but
still be capable of easy movement, the wire will shut off the needle
port (22) from the needle bevel (33) whenever the wire passes the
port (22) by a reasonable distance. The valve action stems from
simple surface tension. The sample fluid exerts surface tension
between the wall of the hollow needle (4) and the guide wire (2):
this surface tension will stop the movement of fluid. The port (22)
and the bevel (33) will be "shut-off". This simple mechanism
will stop any fluid from exiting the sample chamber through bevel
(33), which will be in the sample chamber whenever the needle is
retracted, and out through port (22) into the hollow plunger (5).
The same action will stop the sample from becoming contaminated
(reverse flow from the port through the bevel). Note how the valve
will also stop the fluid sample frown outgasing, thus assuring a
true sample when that sample reaches the laboratory.
Note that it might be possible to design or choose a needle length
that would keep the bevel port (33) on the outside of the barrel
and yet within the confines of the Luer Lock portion of the syringe
barrel (8). This device considers this approach but believes that
safety requires complete retraction of the hollow needle (4) to
within the confines of the barrel.
The hollow plunger assembly is shown generally as 14 in FIG. 4.
Essentially this plunger functions exactly the same as any standard
syringe plunger except that first it is hollow, second it has retraction
locking ramps (34), third it has a slot (24), fourth it has an opening
for the needle seal system (25) and fifth it has a needle seal system
(in general item 7 but specifically 7A or 7B depending on embodiment).
Like the normal syringe plunger it has a piston (6) which sets the
volume of a pressure sample, draws a vacuum for an aspirated sample
or causes a pressure for an injection syringe. The thumb flange
(23) allows the thumb to exert the necessary force against the piston
or allows the finger to draw the piston backwards within the syringe
barrel. Slot (24) is sized to allow lever arm (20) to pass through
it. Retraction locking ramps (34) are essentially molded catches
that latch against the needle head (3) preventing the needle from
being extended once the ramps catch the needle head (3). The needle
assembly (generally 12) passes through the opening in the plunger
(25) and then through the enlarged plunger needle seal opening (27).
The plunger needle seal (generally 7) is retained within the opening
(27), against opening (25), and about the needle (4). In the pressure
filled sampler embodiment, the plunger needle seal consists of a
packing formed of "microfilter" material (7A). Microfilter
material is hydrophobic, in that it will allow entrained air to
pass readily through it but will swell and stop fluids from passing
through it. Thus the microfilter (7A) will seal sample fluids and
yet allow the hollow needle (4) to slide up through so that the
needle can be retracted.
The completed plunger and retractable needle assembly (generally
18) for the sampler (pressure or aspirated) embodiment is shown
in FIG. 5. Assembly is a matter of choice but the method used by
the inventor is as follows:
First, insert the hollow needle assembly (12) through the slot
(24) and passing the needle through the opening (25): slightly pry,
the slot open and press the needle head (3) through the slot and
into the hollow center of the plunger.
Second, draw the needle assembly back up into the hollow plunger.
Third, install the plunger needle seal (7) [this could have been
done earlier].
Fourth, install the plunger piston (6) [this could have been done
earlier].
Finally, install the guide wire/valve (11) assembly by inserting
through the plunger opening (39), guiding it through the hollow
needle (4). Guide wire head (1) is then force fitted into the plunger
opening (39) completing the needle retraction sub-system (generally
18).
The barrel assembly (generally 15) shown in FIG. 6 is a standard
syringe barrel assembly. A barrel assembly consists of the finger
flange (28) with its associated flats (29); the barrel itself (8);
and the tip (not numbered) in which there is generally a "Luer
Lock" thread (35) for the receipt of a standard needle. An
alternate assembly is shown in FIG. 6A; the only difference being
in the finger flange (28) design which has a slot (29A) rather then
the flats of a standard barrel. The barrel tip (not numbered) also
contains a nipple (30) with an opening through which the hollow
needle (4) can pass. In this instant invention the barrel assembly
also includes a barrel cap sub-assembly (generally 16) which consists
of the barrel needle seal (9) and the barrel cap (10). The barrel
cap (10) has corresponding Luer Lock Tabs [or flats](36) which allow
the cap to be drawn up tight against the barrel nipple via the Luer
Lock threads (35) thus forcing the barrel needle seal (9) against
the barrel nipple and its opening (30).
In discussing the pressure sampler and its preferred embodiment,
the preferred barrel needle seal assembly is shown in FIG. 7A. FIG.
7A is a cross-section of the barrel cap assembly shown in place
on the barrel. The barrel cap (10) is shown with flange (46) which
is not necessary for the pressure sampler mode, but is shown as
most manufacturers would prefer to make one part for use in all
versions of the safety syringe. The cap (10) holds a packing gland
(38) in place against the barrel nipple (30). After the hollow needle
is placed through opening (30) in the barrel [during assembly],
packing gland (38) is squeezed between the barrel nipple and the
barrel cap by simply tightening the barrel cap within the Luer Lock.
The tightened packing gland (38) then forms the barrel needle seal
(9) for the pressure sampler. Experience has shown that a tight
seal is needed at the barrel end of the needle to stop fluids from
escaping around the needle.
FIG. 7D shows an o'ring variation of the barrel needle valve seal.
This alternate embodiment will work for all modes of operation of
the safety syringe; however, slight leakage will occur when the
needle is retracted. Thus in the sampler modes, a packing gland
or self sealing rubber seal must be added to prevent leakage or
contamination of the sample when the needle is retracted. The packing
gland (38) of FIG. 7A or the rubber tip (41) of FIG. 7B can be utilized.
The alternate barrel needle seal assembly consists of the barrel
cap (10) with an o'ring seat (46) molded within. An o'ring (47)
is placed in the seat and the cap is then placed over the hollow
needle (4) and tightened against the barrel using the Luer Lock
(35 and 36). It should be realized that the cap (10) will have to
be manufactured to fit different sized needles as needed. The preferred
embodiment for the pressure sampler barrel cap assembly will fit
a number of different sized needles and would be cheaper and simpler
to manufacture.
FIG. 7E shows the barrel needle seal assembly moved to within the
barrel itself. This variation of the seal also uses an o'ring (49)
placed within an o'ring seat (48) molded within the barrel nipple.
This variation of the barrel needle seal will function with all
embodiments of the safety syringe. The drawback is manufacturing
complexity and the fact that the barrel will no longer be a manufactured
standard thus increasing its cost.
The completely assembled pressure sampler is shown in FIGS. 8A
through 8D. All that remains is to explain its operation. The pressure
sampler as it would appear when removed from its sanitary container
is shown in FIG. 8A. The hollow needle (4) is shown in its extended
position although it would be possible to package the device with
the needle retracted. The hollow needle is latched in its extended
position by the lever arm latch (21) located on the lever arm (20).
The lever arm latch (21) catches under the finger flange (28) of
the barrel and holds the hollow needle (4) extended. In the extended
position the needle port (22) is at or near the bottom of the barrel
and the guide wire/valve (2) is located above the port (22) thus
leaving the port in communication with the needle bevel (33). To
use the device in its pressure sampler embodiment, the hollow plunger
is withdrawn, as shown in FIG. 8B, to the required sample volume.
The sampler is then inserted and arterial pressure will force the
blood sample through the bevel (33), through the port (22) and into
the barrel. Air (or inert gas) within the barrel will be displaced
through the "microfilter" plunger needle seal assembly
(7) and into the hollow plunger. That air will then flow out of
the plunger slot (24) to the atmosphere. Once the blood sample reaches
the "microfilter", it will swell and shut off all flow
as well as seal the hollow needle (4) from the hollow plunger (5).
That is no fluid will escape past the plunger needle seal (7). The
sampler is then withdrawn from the subject, which now exposes the
contaminated needle (4) and the needle bevel (33).
The hollow needle (4) is easily retracted to its SAFE position.
The worker rotates the plunger assembly so that the needle lever
latch (21) is aligned with the barrel finger flats (29). In the
alternate embodiment shown in FIG. 6A, the lever latch (21) would
be rotated until it aligns with the slot (29A) at which the latch
would clear the finger flange (28A). This means that the latch (21)
is no longer constrained by the flange and the lever arm (20) may
be pulled upwards towards the top of the hollow plunger (5). The
lever arm (20) slides up the hollow plunger (5) via the slot (24)
in the plunger. As the hollow needle moves up inside the hollow
plunger the needle bevel (33) moves inside the syringe barrel. At
the same time the guide wire/valve (2), which is fixed, slides within
the hollow needle sweeping sample fluid contained within the hollow
needle into the barrel via port (22) which is the shortest flow
path. The guide wire/valve (2) will eventually pass port (22) and
seal it. The needle port (22) will eventually pass the plunger needle
assembly (14) and position itself within the hollow plunger (5).
If the port (22) were not valved shut by the needle guide wire/valve
(2) fluid could leak into the hollow plunger (5) and come out of
the slot (24) and into contact with the world. In a similar manner,
the outside world cannot come into contact with the sampled fluid
as the communication between the needle port (22) and the bevel
(33), which is now within the barrel, is cut off by the guide wire/valve
(2). Finally, as the hollow needle (4) retracts past the barrel
needle seal assembly (16) the packing gland (38) will close about
itself and retain the sample fluid within the barrel.
As the lever arm (20) is drawn upwards within the plunger, the
needle head (3) eventually comes in contact with the retraction
locking ramps (34). These ramps allow the needle head to slide inside
them but do not allow the head to slide out. Thus the retraction
ramps (34) permanently latch the needle (4) in a retracted position.
It should be apparent that the retraction ramps (34) could be modified
to allow a further extension of the needle. The fully retracted
and latched needle is shown in FIG. 8C. The sample contained with
the barrel is fully isolated from the outside world by the guide
wire/valve (2), the plunger needle seal (generally 7) and the barrel
needle seal (9). Thus the sample cannot be contaminated nor can
the sample leak out and contaminate others.
All that remains is to eject the sample into an analysis machine.
This operation is shown in FIG. 8D where the plunger (5) has been
pushed back down into the barrel (8) thus forcing the sample fluid
out past the barrel seal (7), through the cap (10) and into the
machine. If difficulty is experienced in forcing the fluid out the
packing gland (38) can be loosen by unscrewing the cap (10) or a
special form of the gland which incorporates a check valve could
be employed. Note that the retracted hollow needle (4) remains within
the syringe and does NOT interfere with the ejection operation.
The alternate variations of the barrel needle seal (9) would work
in a similar manner. In the case of o'ring seals (47) in FIG. 7D
and (49) in FIG. 7E there could be contamination of the fluid or
some fluid could leak out. The problem could easily be solved by
adding a resealable rubber covering of the type used in serum vials.
In fact a modified self closing o'ring or a packing gland could
be used. These systems would increase the cost of manufacture but
are not beyond the scope of this invention or disclosure.
Turning now to another major embodiment of the invention which
also involves sampling but in the form of aspiration sampling. This
technique is similar to pressure sampling except that the sample
is drawn from the subject by vacuum within the barrel (8). The vacuum
is formed by inserting the sampler with the-plunger (5) in the full
down position and then slowly withdrawing the plunger (5) until
the required sample is drawn into the barrel (8). The only change
needed in the preferred embodiment of the pressure sampler previously
described is in the plunger needle seal assembly. This seal must
be capable of holding a vacuum. Thus the assembly shown in FIG.
4 as item 7B would be a rubber seal rather than the "microfilter"
seal (7A). Of course the seal could be an o'ring in a seat molded
into the plunger opening (25).
An O'ring seal system for the plunger opening (25) is shown in
FIG. 9. An O'ring seat (51) is molded into the plunger opening (25)
and an 0'ring (50) is placed in that seat. The piston (6) is shown
with a microfilter (7A) and piston spacers (52). This particular
embodiment will now function exactly like a presently available
sampling syringe which is designed to operate in both the aspiration
mode and the pressure mode. When the syringe is operating in the
pressure mode, displaced air within the barrel passes through the
microfilter (7A) and between the molded hollow plunger (5) and the
space caused by the piston spacers (52). When fluid reaches the
microfilter, it seals off. To eject the sampled fluid, the plunger
is pressed downwards and the piston will press hard against the
piston spacers (52) and the plunger lip (54) to form a complete
pressure seal. When the syringe is used in the aspiration mode a
vacuum must be formed within the barrel when the plunger (5) is
withdrawn. This is easily accomplished by the piston (6), for as
it is pulled back, the piston moves downward and seals against the
plunger lip (54). Thus it can be seen that this invention can operate
very easily in conjunction with an existing combination mode (pressure
and aspiration) sampler. FIG. 9 also illustrates how an O'ring plunger
seal system would operate in the injection mode. It would be possible
to mold the o'ring into the needle opening within the piston (6).
These various seal system are considered to be within the scope
of this invention.
The barrel needle assembly has several more options. The packing
gland system of the pressure sampler can still be employed, but
the preferred embodiment would be that shown in FIG. 7B. A minor
modification or manufacturing step is added to the barrel cap (10).
The cap (10) needs a needle guide (42) which is placed inside the
cap opening as shown. In addition an outside rubber cap (41) is
placed over the outside of the barrel cap (10) and held in place
by lip (46). The rubber cap (41) is the same material that is used
in serum vials which is a self sealing silicon rubber or equivalent.
As vacuum is drawn within the barrel, atmospheric pressure will
force the rubber against the hollow needle (4) thus maintaining
the seal. After the needle (4) is retracted the rubber cap (41)
will self seal and stop any chances of contamination. In a similar
manner the barrel needle assemblies of FIGS. 7D and 7E could be
used. The problems and limitations discussed under the pressure
sampler embodiment would also apply to this variant on the seal.
The operation of the aspiration sampler follows standard procedure.
With the needle extended as in FIG. 8A the needle (4) is inserted
into the subject. The plunger (5) is then withdrawn and the sample
passes up the needle (4) into the barrel (8) in exactly the manner
described above. Once the required volume is obtained, the needle
(4) is withdrawn from the subject exposing the contaminated bevel
(33). The needle (4) is then retracted in the manner described above.
The port (22) will seal, the plunger will seal, and the sample will
be sealed.
Turning now to the last major embodiment of the instant invention
in which the safety syringe is used for pure injection. The syringe
would of course be used with the needle (4) extended and the retraction
scheme is exactly as previously described. There are some major
or minor changes as seen fit. First, the safety syringe does not
need the needle port (22) shut off valve as there will be no fluid
in the barrel to leak through this port after injection and after
retraction of the needle. Second the needle head (3) must be capped
(i.e. the opening passing through it must be closed) or the opening
should not be present because the guide wire valve assembly is not
required.
Use of the guide wire valve assembly would be a pure manufacturer's
choice--money could be conserved by leaving this assembly out. This
embodiment is shown in FIG. 5A. Here the opening in the top of the
plunger head or thumb flange (39) could be capped with a plug (37),
although this is not strictly necessary, for the comfort of the
technician. The plunger needle seal (7B) must be capable of resisting
pressure which can be accomplished by a rubber packing or through
an o'ring seal. Since injection needles are small there is a possibility
of fracture at the needle port (22). Safety barbs (40) will be needed
to ensure that a broken needle will come out of the subject. The
safety barbs (40) would be designed to catch against the tip of
the barrel needle (30) and not be able to pass through it. Thus
if a needle does indeed break at the needle port then it will stay
attached to the safety syringe.
The barrel needle seal assembly (16) can take several forms. The
original packing gland of FIG. 7A can be used or the o'ring variations
of FIGS. 7D and 7E may be employed. The o'ring variations would
be ideal in this case as leakage after the needle is withdrawn is
not critical nor is there any requirement for sealing of the sample
within the barrel [there is nothing in the barrel]. The only disadvantage
would be cost. An alternate barrel needle seal assembly is shown
in FIG. 7C. This seal assembly also employs a needle guide (45)
and resealable rubber gasket (43) as explained for the aspirator
sampler. Because the pressure is exerted from within the barrel
the resealable rubber gasket (43) must be placed inside the barrel
cap (10). The rubber gasket (43) is placed over the needle guide
(45) and held in place by tabs (44) on the needle guide. This assembly
is placed within the barrel cap (10) which in turn is screwed in
place on the Luer Lock (35). The seal assembly is then held in place
between the barrel nipple (30) and the barrel cap (10). The hollow
needle (4) passes through the rubber gasket (43). Whenever injection
pressure is applied to the device the rubber will force up against
the hollow needle (4) and seal.
One more variation of the barrel needle seal is illustrated in
FIG. 9. Here the barrel cap (10) has an 0'ring (47) and an 0'ring
seat (46) molded into its tip. This O'ring will tightly seal the
hollow needle (4). In order to make certain that no sample fluid
drips from the barrel and to ensure that the sample fluid cannot
be contaminated, a self sealing silicon rubber seal (53) is placed
between the barrel nipple (30) and the inside of the barrel cap
(10). The action of the Luer lock (35 and 36) will hold this rubber
seal in place.
Operation of the safety syringe as an injection syringe would be
the same as a regular syringe. The serum would be drawn into the
barrel (8) via the needle bevel (33) and the needle port (22) whenever
the plunger is withdrawn. The needle would inserted into the subject
and serum would flow in the reverse direction whenever the plunger
is depressed. After use, the needle would be retracted in the manner
already explained.
As can be seen the safety syringe will meet all criteria for a
retractable needle safety syringe. The instant invention will serve
as a simple injection device and as a sampler device in two modes,
pressure or aspiration. The device can serve as its own protector
before use by packaging it with the needle retracted. The device
can be manufactured from mostly standard syringe components, but
variations in seal arrangements are available to improve the device.
It would be possible to package the device with preloaded serum
or to supply the device "heparinized" when used for Arterial
Blood Gas Sampling. It should be apparent that the descriptions
in this invention show three uses for the device but the use is
only limited by the imagination of the user. The device is designed
for medical use but could easily find use in the laboratory; for
example, in gas chromatography. |