Needle stopper and needle removal device

A needle stopper for use with a hypodermic syringe such as an arterial blood gas syringe includes a shell having a bottom, an open top and a needle-receiving chamber therebetween. The bottom is configured to support the needle stopper in an upright orientation. The needle-receiving chamber is dimensioned to receive needle cannula and to engage a needle hub connected to the cannula. The chamber is at least partly filled with a sealing material that can occlude the tip of a needle cannula. The upright orientation of the needle stopper enables one-handed insertion of the needle cannula into the needle-receiving chamber for occluding the needle tip. Engagement of the needle stopper with the needle hub enables safe and convenient separation of the needle hub and cannula from the syringe barrel for disposal. The tip of the syringe barrel then may be capped and sent to a laboratory for analysis of fluids therein.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The subject invention relates to a stopper for a needle of a syringe such 
as an arterial blood gas syringe, and more particularly to a stopper which 
enables one-handed covering and sealing of the needle, and a subsequent 
safe separation and containment of the needle from the syringe barrel. 
2. Description of the Prior Art 
A hypodermic syringe includes a syringe barrel having an open proximal end 
and an opposed distal end. A cylindrical wall extends between the proximal 
and distal ends and defines a fluid receiving chamber in the syringe 
barrel. The distal end of the syringe barrel includes a passage that 
extends therethrough and communicates with the chamber. The distal end 
also is configured to receive a needle cannula which communicates with the 
passage and the chamber. The prior art hypodermic syringe also includes a 
plunger in sliding fluid tight engagement with the cylindrical wall of the 
chamber. Sliding movement of the plunger toward the distal end causes 
fluid in the chamber to be evacuated through the passage and the needle 
cannula. Conversely, sliding movement of the plunger toward from the 
proximal end draws fluid through the needle cannula and the passage and 
into the chamber. 
Most hypodermic needles are provided with needle shields or covers to 
protect the needle from damage and contamination during shipment and 
transfer to the patient's room as well as to protect health care workers 
from accidental needle sticks involving clean unused needles. The needle 
shield or cover typically is removed immediately prior to use of the 
hypodermic syringe. A hypodermic syringe that is used for an injection 
typically will be discarded into a special sharps collector immediately 
after injection to further protect against accidental needle sticks. 
However, hypodermic syringes such as arterial blood gas syringes that are 
used to withdraw fluid from a patient cannot be discarded until the fluid 
has been properly evaluated. To protect against accidental needle sticks 
at this stage, the needle cannula may be removed or covered with a needle 
stopper. 
Some medical procedures require periodic sampling and evaluation of 
arterial blood. For example, blood may be evaluated for content of carbon 
dioxide, oxygen and pH. Arterial blood may also be evaluated for 
concentration of electrolytes, such as sodium and potassium. 
An arterial blood gas syringe is similar to a hypodermic syringe but it 
also includes an anticoagulant such as liquid or dry heparin in the 
chamber to prevent blood clotting. Also, an arterial blood gas syringe 
usually contains means associated with the plunger which allows gas, such 
as air, to leave the chamber but blocks the exit of liquid such as blood. 
The use of an arterial blood gas syringe for arterial blood gas analysis is 
difficult for several reasons. Arteries often are deeper in the body of 
the patient, and hence more difficult to locate. Accordingly, the 
respiratory therapist, technician or phlebotomist must insert the needle 
fairy deeply, thereby causing considerable discomfort to the patient. 
After removal of syringe from the patient, the therapist must immediately 
apply pressure to the punctured artery to prevent bleeding. Proper 
evaluation of arterial blood gas requires prompt sealing of the arterial 
blood sample to prevent reaction of the blood with ambient air. However, 
the realities of the procedure often require the respiratory therapist to 
use one hand for applying pressure to the puncture wound, thereby leaving 
only one hand to seal the needle cannula and to handle the blood filled 
syringe. 
The prior art includes arterial blood gas syringe kits with components to 
seal the needle cannula after withdrawal from the patient. In particular, 
a prior art kit includes an arterial blood gas syringe and a cube of 
rubber, plastic or cork approximately 1 cm.sup.3. The therapist usually 
places the cube on a flat surface near the patient. An arterial blood 
sample then is obtained in the standard manner. After withdrawing the 
needle cannula from the patient, the therapist applies pressure to the 
wound with one hand, while using the other hand to urge the tip of the 
needle cannula into the cube on the work surface near the patient. The 
cube occludes the needle cannula to prevent blood/air interaction while 
the respiratory therapist attends to the hemostasis. The therapist then 
shakes the syringe to mix the blood and the heparin anticoagulant in the 
syringe barrel. The needle is then removed by using a hemostat or by hand, 
and the used needle is discarded into an appropriate safety collector for 
sharp objects. The syringe tip then is covered with a tip cap. The blood 
filled syringe with tip cap is usually placed in a container including ice 
and sent to a laboratory for analysis. 
The prior art arterial blood gas kit has several disadvantages. For 
example, the small rubber cube neither guides nor limits the movement of 
the needle. Thus, the needle can be skewed during insertion by the 
respiratory therapist or it can bend during insertion to project from a 
side surface of the small rubber cube. Similarly, the small cube can tilt 
during insertion thereby enabling the tip of the needle to pass entirely 
through the cube. In either case, the tip of the needle is exposed and 
enables ambient air to react with the arterial blood in the syringe. 
Furthermore, the exposed tip of the needle can lead to accidental needle 
stick. Means for removing the needle from the syringe barrel may reduce 
the risk of accidental needle stick, but a separate removal means in the 
arterial blood gas kit adds to the complexity. 
As noted above, the prior art also includes many types of needle shields 
that can be placed over the needle to prevent accidental puncture. 
However, these prior art needle shields generally do not occlude the 
needle tip, and generally are not well suited for the one-handed sealing 
that is realistically required for arterial blood gas procedures. 
SUMMARY OF THE INVENTION 
The subject invention is directed to a needle stopper which enables 
efficient one-handed occlusion of a needle cannula. The stopper is 
configured to prevent improper insertion or over insertion of the needle 
cannula, and thereby helps avoid accidental needle sticks. The stopper 
also is configured to enable safe efficient removal of the needle cannula 
from the syringe barrel. 
The needle stopper of the subject invention includes a substantially rigid 
shell having an upstanding generally tubular side wall with opposed top 
and bottom ends and a needle-receiving chamber therebetween. The height of 
the tubular side wall, as measured between the top and bottom ends, is 
greater than the length of the needle cannula to be inserted therein. The 
bottom of the tubular side wall may be dimensioned and configured to 
define an efficient support for the upstanding side wall. For example, the 
side wall may be of frustoconical or pyramidal shape, with the bottom end 
of the side wall defining a greater cross-sectional area than the top end. 
It is an important advantage of the present invention that the outwardly 
tapering side wall of the shell minimizes the possibility of the needle 
tip engaging the side wall before complete insertion of the needle cannula 
into the shell. Engagement of the side wall by the needle before complete 
insertion could cause the sharp needle point to pass through the side wall 
and project outwardly therefrom. The shell may also include a support 
flange extending outwardly from the bottom end of the side wall to ensure 
support of the shell in an upright orientation. 
The top end of the shell is open and dimensioned to enable insertion of the 
needle cannula therein. The top end of the shell may further be configured 
to engage a needle hub and to facilitate the separation of the hub from a 
syringe barrel. 
The needle stopper of the subject invention further includes a sealing 
material in the needle-receiving chamber. The sealing material is selected 
to permit easy penetration of the needle cannula, while simultaneously 
occluding the needle tip to prevent deterioration of the arterial blood 
sample. For example, the sealing material may comprise clay, wax or 
certain rubbers and plastics, or other suitable materials. 
The subject invention may also be directed to a kit of parts for 
efficiently and safely drawing and protecting a sample of arterial blood 
gas. The kit of parts may include an arterial blood gas syringe assembly 
containing anticoagulant such as heparin, and the above described needle 
stopper. The kit may further include a tip cap for protectively enclosing 
the passage through the syringe barrel after removal of the needle hub 
therefrom. 
The needle stopper of the subject invention is usually used by initially 
supporting the bottom end on a work surface in proximity to the patient. A 
respiratory therapist then removes the shield from the needle cannula and 
draws an arterial blood sample. The respiratory therapist uses one hand to 
withdraw the needle from the patient, and the other hand to apply pressure 
to the puncture wound. While maintaining pressure with one hand, the 
respiratory therapist inserts the tip of the needle cannula into the open 
top end of the needle stopper. The needle cannula is advanced sufficiently 
for the needle tip to enter the sealing material and for the needle hub to 
engage the top end of the shell. The therapist then mixes the blood and 
the anticoagulant, such as heparin, in the syringe barrel. When hemostasis 
has been achieved, the therapist engages the syringe barrel in one hand 
and the shell of the needle stopper in the other hand. Movement of the 
syringe barrel relative to the needle stopper separates the needle hub 
from the syringe barrel. The passage of the syringe barrel then is capped 
and the safely connected needle cannula, hub and stopper are discarded in 
a sharps collector. Finally, the efficiently sealed arterial blood sample 
is sent to the laboratory for analysis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A kit of components for an arterial blood gas procedure is identified 
generally by the numeral 10 in FIG. 1. The kit includes a hypodermic 
syringe 12, a needle stopper 14 and a tip cap 16 all of which are 
protectively enclosed in a sealed protective package 18 which can be made 
of many materials and structures including foil and plastic sheet 
material. 
Arterial blood gas syringe 12 includes a generally cylindrical syringe 
barrel 20 having an open proximal end 22, a distal end 24 and a fluid 
receiving chamber 26 extending therebetween. The chamber contains an 
anticoagulant such as liquid or dry heparin. The distal end of syringe 
barrel 20 includes a tip 28 having a passage 30 extending axially 
therethrough and communicating with the chamber. A collar 32 is preferably 
disposed coaxially around syringe tip 30 and is provided with an array of 
internal threads. A needle cannula 34 is rigidly mounted to a hub 36 which 
is removably engaged with the internal threads of collar 32 at the distal 
end of syringe barrel 20. The syringe can also be made without a collar 
wherein the hub is held onto the barrel through a frictional interference 
fit between the tip and the hub. A shield 38 is removably engaged over the 
needle cannula to avoid accidental needle sticks and contamination prior 
to use. 
A sealing plug or stopper assembly 40 is mounted to the distal end of a 
plunger rod 41 and is in sliding fluid tight engagement with the syringe 
barrel. The sealing plug of an arterial blood gas syringe may include a 
filter, such as a hydrophobic filter, to permit air to pass from the blood 
receiving space in the chamber while preventing the flow of blood beyond 
the sealing plug. Accordingly, the stopper 40 initially acts as a vent 
plug and later as a sealing plug when the filter is contacted by blood. 
Such a stopper is taught in U.S. Pat. No. 4,340,067. 
Tip cap 16 of the arterial blood gas kit is dimensioned and configured to 
engage tip 28 of syringe barrel 20 for sealing passage 30 therethrough and 
preventing a reaction between ambient air and arterial blood in chamber 
26. Tip caps are usually made of rubber and include a closed end cavity 
that receives a syringe tip. As will be explained further herein, the tip 
cap may be mounted to syringe tip 28 after needle cannula 34 and hub 36 
have been separated. A typical tip cap is illustrated in U.S. Pat. No. 
4,444,310. 
Needle stopper 14 is illustrated in greater detail in FIGS. 2, 3 and 4. The 
stopper includes a shell 42, which preferably is unitarily molded from a 
thermoplastic material exhibiting rigidity, hardness and resistance to 
needle puncture. However, the shell may be made of glass, metal or other 
materials resistant to needle puncture. Shell 42 includes a generally 
frustoconical side wall 44 having a bottom end 46, an opposed open top end 
48 and a needle-receiving chamber 50 defined within the side wall and 
extending between bottom and top ends 46 and 48. The frustoconical side 
wall of shell 42 defies a height "A", as depicted in FIG. 2, which exceeds 
the overall length of that portion of needle 34 which projects out of hub 
36 on the arterial blood gas syringe. Frustoconical side wall 44 is 
configured such that the top end thereof defines the minor cross-sectional 
dimension and the bottom end thereof defines the major cross-sectional 
dimension. As will be explained further herein, this configuration is an 
important advantage of the present invention because it reduces the 
potential of a needle inserted into open top end 48 from snagging or 
piercing side wall 44 as the needle is advanced into chamber 50. The 
orientation of frustoconical side wall 44 also contributes to stability of 
needle stopper 14. Stability is further enhanced by a generally planar 
base 52 extending outwardly from bottom end 46 and defining a major 
cross-sectional dimension for shell 42. 
The frustoconical side wall of shell 42 is characterized by a plurality of 
longitudinally extending ribs 54 extending outwardly therefrom. The ribs 
define surface irregularities that facilitate gasping and rotation of the 
needle stopper as explained further herein. 
Open top end 48 of frustoconical side wall 44 is preferably characterized 
by an outwardly directed needle entry chamber 56 leading into the 
needle-receiving chamber. It is also within the purview of this invention 
to provide a flared structure at the open top end to help guide the needle 
into the needle-receiving chamber. A hub-engaging section 58 of 
needle-receiving chamber 50 is disposed directly below chamfer 56 and is 
tapered slightly inwardly to conform to the shape of the needle hub on the 
arterial blood gas syringe. 
The frustoconical side wall of shell 42 is further characterized by a 
plurality of inwardly directed locking protrusions 64 in proximity to open 
top end 48. The locking protrusions are dimensioned to engage the outer 
surface regions of the needle hub after sufficient insertion of the needle 
cannula into needle-receiving chamber 50. 
The needle stopper is further characterized by a sealing material 66 
disposed in needle-receiving chamber 50 of shell 42 from a location 
adjacent the bottom to a location intermediate the top and bottom. The 
sealing medium may be made of clay, wax, natural rubber, synthetic rubber, 
thermoplastics, thermoplastic elastomers or polymeric foam that will not 
prevent penetration of the needle cannula, and that will occlude or 
prevent environmental air contact to the interior of the needle tip after 
sufficient insertion into needle-receiving chamber 50. 
Arterial blood gas kit 10, as shown in FIG. 1 is used by initially opening 
the package 18 and extracting syringe 12 and needle stopper 14. Base 52 of 
shell 42 of the needle stopper is positioned on a work surface of a 
variety of orientations, with horizontal surface 68 being preferred, in 
proximity to the patient, as shown in FIG. 4, such that top end 48 of 
frustoconical side wall 44 projects upwardly from horizontal surface 68. 
The respiratory therapist will then remove needle shield 38 from syringe 
barrel 20 to expose needle cannula 34. The therapist will then insert the 
tip of needle cannula 34 into a selected artery of the patient and will 
cause blood to be drawn into chamber 26 of the syringe barrel. After a 
sufficient quantity of arterial blood has been drawn into syringe barrel 
26, the therapist will exert forces on the syringe barrel with one hand to 
withdraw needle cannula 34 from the patient. The therapist will then 
immediately use his or her other hand to apply pressure to the puncture 
wound for achieving hemostasis. 
As noted above, it is necessary to seal tip 38 of needle cannula 34 quickly 
to prevent reaction between the arterial blood and ambient air. It also is 
important to protect the patient and health care workers from accidental 
needle sticks. The therapist achieves both objectives by aligning the 
syringe with the longitudinal axis of needle stopper 14, and placing the 
tip of needle cannula 34 into open end 48 of shell 42. The respiratory 
therapist then advances needle cannula 34 into open top end 48 as shown in 
FIG. 4. After sufficient advancement, tip 35 of needle cannula 34 will be 
sealingly engaged by the sealing material 66. A therapist will continue 
the axial advancement of the syringe until needle hub 36 is engaged by 
locking protrusions 64 adjacent open top end 48 of the shell of needle 
stopper 14 as shown in FIG. 5. It should be emphasized that this insertion 
of needle cannula 34 into the needle-receiving cavity of shall 42 can be 
achieved by one hand while the respiratory therapist continues to apply 
pressure to the puncture wound of the patient. After complete seating of 
needle cannula 34 and needle hub 36 in needle-receiving cavity 50, the 
therapist may move the syringe, such as by rotation and/or inversion, to 
mix heparin preloaded in the syringe chamber with the arterial blood. 
Once hemostasis has been achieved, the therapist may remove the pressure 
from the puncture wound. The therapist may then grasp the arterial blood 
gas syringe with one hand and the needle stopper with the other hand. 
Axial movement of needle stopper 14 toward syringe 12 will assure the 
therapist of complete seating of stopper 14 onto needle hub 36. The 
therapist may then rotate needle stopper 14 relative to syringe barrel 20. 
Locking protrusions 64 on the shell of needle stopper 14 cause the needle 
hub to rotate with the needle stopper and to disengage from threaded 
collar 32 and syringe tip 28 at the distal end of syringe barrel 20. This 
removal step may also be accomplished in a one-handed procedure if 
hemostasis has not yet occurred. The separated needle cannula 34, needle 
hub 36 and needle stopper 14 may be discarded immediately into an 
appropriate sharps container. It is an advantage of this invention that, 
because the tip of the needle is sealed by the sealing material, blood in 
the needle is not likely to come out of the unsealed end of the needle 
during the disposal step. Tip cap 16 may then be engaged over the tip of 
syringe barrel 12 to seal the syringe and reduce the probability of 
reaction between the arterial blood gas and ambient air. The sealed 
arterial blood gas syringe may then be placed in a plastic bag containing 
ice transported directly to the laboratory for analysis of blood gas 
content. 
Referring to FIG. 7, an alternative embodiment of the present needle 
stopper is illustrated. In this alternative embodiment, the structure of 
the needle stopper is substantially identical to the needle stopper of 
FIGS. 1-6. Accordingly, components that are substantially identical to 
components of FIGS. 1-6 are numbered identically to the components of the 
embodiments of FIGS. 1-6, except a suffix "a" will be used to identify the 
elements in FIG. 7. Needle stopper 70 includes a shell 42a having an open 
top 48a, a bottom 46a having an aperture 71 therein. Penetrable sealing 
material 66a, such as commonly available modeling clay, is provided. 
Sealing means is provided to form a barrier between the chamber an the 
environment at bottom end 46a. In this embodiment the sealing means 
includes elements 73 having a top surface 74 having an adhesive coating 
75. In this embodiment, the element 73 is an adhesive coated laminate of 
paper and plastic which is preferably made of material having the same 
color as the shell so that the needle shield appears to be one piece or 
unitary when viewed from the bottom end. Also, when a soft material such 
as modeling clay is used as the sealing material, element 73 helps keep 
the material within the shell and also prevents transfer of material out 
of the shell through inadvertent contact. In manufacture, the element may 
be applied first if a viscous or setting sealing material is introduced 
into the shell through open end 48a. If the penetrable sealing material is 
inserted into the needle shield, during production, from bottom end 46a, 
element 73 can be attached after the sealing material is in place. 
FIG. 8 illustrates another embodiment of the present needle stopper. In 
this alternative embodiment the structure of the needle stopper is 
substantially similar to the needle stopper of FIGS. 1-6. Accordingly, 
substantially similar components that perform substantially similar 
functions will be numbered identically to those components of the 
embodiments of FIGS. 1-6 except a suffix "b" will be used to identify the 
components of FIG. 8. 
Alternative needle stopper 80 includes a shell 42b having a bottom 46b and 
an open top end 48b and a side wall 44b therebetween defining a needle 
receiving chamber 50b. A penetrable material 66b is disposed in 
needle-receiving chamber 50b. Bottom 46b of the shell includes aperture 81 
and radially inwardly facing circumferential fib 82. The aperture 81 is 
sealed from the environment, at the bottom of the shell, by a rigid 
element in the form of cup-shaped plug 83 made of thermoplastic material. 
Plug 83 includes circumferential annular recess 85 which is shaped to 
receive and engage fib 82 of the shell so that the plug and the shell 
engage each other in a snap-fit arrangement designed to lock the plug in 
place once it is installed. The rigid plug provides a substantial barrier 
preventing improper insertion of the needle cannula into the bottom end of 
the needle shield and also for retaining the penetrable sealing material 
within the shell. 
The shell of the needle stopper of the present invention can be made of a 
wide variety of rigid materials such as thermoplastic, thermosetting 
plastic, metal, glass, and reinforced plastic material such as fiber 
reinforced plastic material. Fiberglass reinforced thermoplastic material 
is preferred because of its low cost and its ability to be molded into a 
structure which is highly resistant to penetration of the needle cannula. 
When properly molded it provides a hard, smooth outside surface which 
makes it difficult to penetrate by a needle cannula even if such attempt 
is made intentionally. Accordingly, the reinforced thermoplastic material 
offers the moldability of the thermoplastic and the surface properties 
approaching glass or metal with respect to needle penetration resistance. 
In summary, a needle stopper is provided for one-handed protection and 
sealing of the needle cannula of an arterial blood gas syringe. The needle 
stopper includes a rigid shell having a bottom end, an open top end and a 
needle-receiving chamber therebetween. The bottom end of the shell is 
configured to support the shell in an upright condition on a generally 
horizontal surface. A sealing material, such as clay including widely 
available modeling clay, wax or certain plastics or rubbers is disposed in 
the needle-receiving chamber to occlude the tip of a needle cannula 
inserted therein. Occlusion of the needle cannula can be carried out 
safely with one hand while the respiratory therapist is using the other 
hand to apply pressure to the puncture wound. After hemostasis has been 
achieved, the respiratory therapist can use both hands to rotate the 
needle stopper relative to the syringe barrel. The engagement of the 
needle stopper with the needle hub will cause the needle hub and the 
needle cannula attached thereto to threadedly separate from the syringe 
barrel for safe discard. This removal step can also be done in a 
one-handed procedure if hemostasis has not yet occurred. The tip of the 
syringe barrel then can be sealed, and the arterial blood sample can be 
transported to a laboratory for analysis.