Medical safety needle and method

A medical safety needle assembly for a hypodermic syringe, catheter or the like. The assembly includes a hollow needle carried by a hub having at least one radially outwardly extending protrusion. A generally cylindrical hollow sheath is positioned telescopically around the hub for relative sliding reciprocal movement therebetween. The sheath, which is injection molded by the collapsible core method of plastic molding, includes at least one set of interconnecting grooves in which the protrusion is guided. A plurality of projections are positioned in the grooves to hold the protrusion, and thus the sheath, in particular locations relative to the hub and needle. First the needle is covered by the sheath to protect the needle prior to use; then the sheath is retracted to expose the needle for hypodermic use; and lastly, the sheath is moved to shield the needle to an even greater extent than it was prior to use to protect personnel from accidental needle sticks. An indicator on the sheath shows whether the needle has been used or tampered with. When in the final position, the sheath is locked to prevent accidental or secondary use of the needle. Also, after use, the needle and hub and protecting sheath may be removed and discarded as a unit from a syringe or other medical device. This feature allows reuse of the medical device while the discarded needle remains shielded.

BACKGROUND OF THE INVENTION 
The present invention relates to a medical safety needle assembly for a 
hypodermic syringe, catheter, or the like. 
Disposable hypodermic syringes, needles for intravenous tubes, and 
catheters are often used for administering medication and performing 
medical procedures such as taking blood samples from patients. Safety is a 
prime concern in light of the spread of body fluid transmitted diseases 
like AIDS, hepatitis and venereal diseases, which have greatly increased 
both the price and the risk of health hazards resulting from accidental 
punctures or "sticks" with contaminated needles. The risk is shared by 
doctors and hospital personnel alike. Presently, safe disposal of used 
syringes is a serious problem due to the possibility of accidental needle 
sticks and due to use of used syringes by addicts for administering 
illicit drugs. 
Presently diabetic patients administer their medication at home. After 
using an insulin syringe, they recap the syringes. However, prior art caps 
can be easily dislocated, thus exposing the needles. While it is difficult 
to implement safety features on insulin syringes, the present invention 
has overcome this problem. As the population ages, there will be a need 
for increased health care. However, due to economic considerations, there 
may be increased pressure for treatment to be provided as out-patient. The 
increased use of this alternative treatment plan will require development 
of devices suitable for non-institutional care. Pre-sterilized disposable 
home-use treatment kits create a need for a safety feature to be 
incorporated in the design of the syringe to reduce the hazards associated 
with disposing of used needle devices. 
In order to solve the foregoing problems, heretofore modified caps or 
safety sheaths have been provided that can be slid over the needle, hence 
eliminating the risky action of recapping the needle. Examples of prior 
art sheath assemblies are disclosed in U.S. Pat. Nos. 4,425,120; 
4,702,738; 4,801,295; 4,915,701 and 4,917,673, the disclosures of which 
are incorporated herein by reference thereto. 
One of the problems which lingers in prior art needle sheathing assemblies 
is that the assemblies are too complicated and expensive and do not permit 
removal and disposal of the protected needle from the medical device such 
as a syringe. In many prior art assemblies, specially designed syringe 
barrels are required to interact with the sheaths, thereby requiring 
additional expense in manufacture. Modification to the needle by having 
the locking mechanism component molded on the needle may cause potential 
problems. During insert molding, the needles have to be inserted into the 
mold. This gives rise to potential catastrophic damage to the mold if the 
needle is not inserted properly, or if the needle falls away from its 
position during the closing cycle of the mold and gets trapped between the 
injection mold sections. Some prior art assemblies involve modifying the 
barrel of the syringe to incorporate the locking mechanism. In these 
assemblies and the sheath includes protrusions that can attach to the 
locking mechanism of the barrel. It is difficult to adapt this design to 
other medical devices because of the bulk created by the required length 
of the barrel safety mechanism. Some prior assemblies have the locking 
mechanism exposed, allowing deactivation of the locking mechanism. 
Further, none of the prior assemblies have the ability to indicate whether 
the syringe has been tampered with or used. 
The present invention is designed to solve or substantially reduce the 
above-described problems. An added feature of this invention is the 
ability to incorporate this design into existing syringes already on the 
market and as an add-on device to present off-the-shelf hypodermic 
syringes. 
SUMMARY OF THE INVENTION 
It is the principle object of the present invention to provide a disposable 
safety needle, wherein the needle can be protected before use, and wherein 
the needle is permanently and irreversibly concealed after use so as to 
avoid accidental needle sticks. 
It is another object of the invention to provide a protective needle 
assembly which can adapt with minimum changes to existing disposable 
hypodermic syringes as an add-on device, and can be removed from a syringe 
or other appliance to allow for the disposal of the protected needle. 
A further object of the invention is to provide a tamper indicator to 
inform the user whether the syringe has been used before or has been 
tampered with. 
A still further object is to provide a protective needle sheath which can 
be formed by the collapsible mold method of injection molding. 
These as well as other objects and advantages will become more apparent 
upon a reading of the detailed description of the preferred embodiments in 
conjunction with the drawings wherein:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the drawings, and FIGS. 1-3 in particular, there is shown 
a medical hypodermic syringe generally referred to by the numeral 10, 
which incorporates the novel features of the present invention. It is 
noted at the outset that due to the advantages of the assembly according 
to the present invention, the invention finds equal utility on a 
hypodermic syringe, a catheter, an intravenous feeding tube and other 
similar medical devices. For purposes of clarity and brevity, the 
invention will be described in connection with a hypodermic syringe. 
Syringe 10 may be of conventional configuration, having an elongated, 
generally cylindrical hollow barrel 12 having a first open end 14 and a 
second open end 16. A plunger 18 extends into barrel 12 through first open 
end 14 and includes a piston (not shown) which is adapted to draw fluid 
into barrel 12 when plunger 18 is drawn outwardly toward open end 14 and 
to expel fluid from barrel 12 when plunger 18 is pushed toward open end 
16, as is conventional. Diametrically opposed ears or wings 19 permit 
gripping of barrel 12 by the fingers while the thumb presses on plunger 
18. Adjacent open end 16 there is attached needle hub 20 carrying hollow 
needle 22 thereon. Needle 22 is formed with a sharpened distal end 24. As 
is conventional, fluid expelled out of barrel 12 by plunger 18 will travel 
through open end 16 and needle 22, to be injected into a patient. 
Hub 20 may be of many different configurations; however, it is important 
that hub 20 include at least one and preferably two, three or four 
radially outwardly extending protrusions 26 (only one being shown for 
clarity). Alternative hub structures 20a and 20b are shown in FIGS. 5 and 
6, respectively, showing protrusions 26a and 26b, respectively. 
In order to protect needle 22 from contamination before use and to protect 
personnel from accidental needle sticks of a possibly contaminated needle 
after use, there is provided safety sheath 28. Sheath 28 is generally 
cylindrical and hollow, sized to telescopically reciprocate over barrel 
12. It is noted that sheath 28 may slidably engage barrel 12. However, 
according to the principles of the present invention there is no need for 
sheath 28 to be in any way supported by barrel 12 as will be explained 
hereinafter. 
As best seen in FIG. 4, sheath 28 has formed in the interior surface 
thereof a set of interconnecting grooves generally referred to by numeral 
30. While only one groove set 30 is shown, it is to be understood that a 
plurality of identical groove sets will be provided, one groove set for 
each protrusion 26 of hub 20. For example, if the hub structure 20a of 
FIG. 5 is utilized, then four identical groove sets 30 will be utilized, 
spaced around the interior of sheath 28 at ninety degree intervals. If the 
hub structure 20b of FIG. 6 is utilized, then two identical groove sets 30 
will be formed in sheath 28 spaced at one hundred eighty degrees from each 
other. 
In the preferred embodiment, groove set 30 comprises three interconnecting 
grooves: a relatively short circumferentially extending starting groove 
32, a relatively short longitudinally extending securing groove 34 and a 
relatively long longitudinally extending retracting groove 36. The width 
of securing groove 34 and retracting groove 36 are such that protrusion 26 
may ride in and be guided by grooves 34 and 36 as sheath 28 is moved 
longitudinally with respect to hub 20. Securing groove 34 runs parallel to 
the longitudinal axis of sheath 28 and communicates between the exterior 
of sheath 28 at the proximal end 28a thereof and one end of starting 
groove 32 located about one quarter of the length of sheath 28 from 
proximal end 28a. Retracting groove 36 also runs parallel to the 
longitudinal axis of sheath 28 and securing groove 34. Retracting groove 
36 extends from just short of the proximal end 28a of sheath 28 to just 
short of the distal end 28b of sheath 28, as best seen in FIG. 4. 
Retracting groove 36 is positioned to intersect with starting groove 32 at 
the other end thereof opposite the end intersecting with securing groove 
34. 
Retracting groove 36 includes adjacent its distal end a temporary locking 
means comprised of a radially inwardly extending projection 38. As seen in 
FIG. 7, projection 38 is rounded on both sides, providing camming surfaces 
which allow protrusion 26 to pass thereover in both directions of 
longitudinal travel of protrusion 26 within retracting groove 36. Adjacent 
the proximal end of retracting groove 36 is a permanent locking means 
comprised of a radially inwardly extending projection 40. As seen in FIG. 
8, projection 40 includes a camming surface 42 on one side only, allowing 
protrusion 26 to pass over projection 40 only in the direction of the 
arrow. After protrusion passes over projection 40 and the members spring 
back to their original shapes, protrusion 26 will be blocked by side 44 of 
projection 40 from moving in the direction opposite the arrow. 
Securing groove 34 includes, just before the intersection of securing 
groove 34 and starting groove 32, a permanent locking means comprising a 
projection 46. Projection 46 is formed like projection 40 and permits 
movement of protrusion 26 only in the direction toward starting groove 32. 
Starting groove 32 also includes a permanent locking means comprising a 
radially inwardly extending projection 48 positioned between the 
intersection thereof with securing groove 34 and the intersection thereof 
with retracting groove 36. Projection 48 is similar to projection 40 and 
permits movement of protrusion 26 thereover only in the direction from 
securing groove 34 to retracting groove 36. 
Syringe 10 is prepared for use in accordance with the present invention, 
either during manufacture or by retrofitting it with sheath 28 after 
purchase of a standard off-the-shelf syringe. To prepare syringe 10 for 
use, protrusions 26 are initially inserted into groove sets 30 through the 
open proximal ends of securing grooves 34. For simplicity, the operation 
will be described with reference to a single protrusion 26 as it is guided 
by a single groove set 30. 
As shown in FIG. 1, protrusion 26 slides into securing groove 34 and over 
locking projection 46 to secure protrusion 26 in a starting position at 
the intersection of securing groove 34 and starting groove 32. In this 
starting position, sheath 28 extends beyond sharpened end 24 of needle 22 
to protect the needle from contamination. Preferably a disposable cap (not 
shown) is placed on the distal end of sheath 28 to further protect needle 
22 prior to use, or the unit is wrapped in paper during manufacture. 
Further, in this starting position sheath 28 is locked from longitudinal 
movement in either direction with respect to hub 20 and needle 22. 
When syringe 10 is to be used, the optional cap is removed and sheath 28 is 
rotated slightly with respect to hub 20 with enough force such that 
protrusion 26 passes over projection 32 and into a starting position in 
groove 36. At this point protrusion 26 may be slid down toward the distal 
end of sheath 28 until it passes over temporary locking projection 38. At 
this point, needle 22 is exposed for use as shown in FIG. 2. 
After syringe 10 has been used and needle 22 may be contaminated, sheath 28 
is slid away from the user to again cover needle 22. This is accomplished 
by applying sufficient force to allow protrusion 26 to again pass over 
projection 38 in the opposite direction. Protrusion 26 then passes within 
retracting groove 36 until it passes over locking protrusion 40 which 
permanently locks protrusion 26 at the proximal end of groove 36 as shown 
in FIG. 3. It is noted that in this locked position sheath 28 extends 
further over the sharpened end 24 of needle 22 to provide even greater 
protection from accidental needle sticks then was the case prior to use. 
Also the fact that sheath 28 is locked in a different longitudinal 
position relative to barrel 12 than when in its starting position, acts as 
one indication that the syringe has been used. 
Another optional method which may be employed in the present invention to 
indicate whether or not the medical device has been used or tampered with 
is to place a dot of ink 50 (FIG. 4) on projection 48 in starting groove 
32. The dot of ink 50 would be easily rubbed off and the movement of 
protrusion 26 over projection 48 would rub off dot 50. As sheath 28 is 
transparent, the user could see whether or not dot 50 was present and thus 
know whether sheath 28 had at any time been moved from its initial 
starting position. 
After use of the syringe 10 or other medical device with and sheath 28 
extended over needle 22 as shown in FIG. 3, hub 20, needle 22 and 
protective sheath 28 may be removed as a unit from syringe barrel 12 or 
other device. Thus, needle 22 may be disposed of with the protective 
sheath 28 locked in place around the possibly contaminated needle. 
A simplified construction of the sheath, which is used in a slightly 
different manner, is shown in FIG. 4A and labelled 28'. In this embodiment 
of the invention, the securing groove 34 and the long longitudinally 
extending retracting groove 36 are disposed along the same line. When 
using sheath 28', the syringe barrel is inserted through the opening in 
sheath end 28b while the needle/hub combination is held at the other end. 
The hub is then connected to the syringe in the conventional manner and 
the protrusion on the hub is inserted into groove 34. The protrusion 26 
rides first in groove 34 until it passes over locking projection 46 
disposed in the groove. Once protrusion 26 passes projection 46, the 
sheath can no longer be removed from the hub (although hub and sheath can 
be removed as a unit from the syringe). 
In this embodiment, a two-sided projection 40, is provided in the groove 
set between locking projection 46 and holding projection 38. Projection 
40' in this embodiment holds the sheath 28' in a the retracted position 
with respect to the hub until it is desired to cover the needle. Once the 
needle is used, sheath 28' is moved (downwardly if disposed in the 
position shown in FIG. 4A) until protrusion 26 passes over projection 38. 
At this point the needle is covered. Projection 38 in this embodiment is a 
locking projection, so that it locks the sheath in place over the needle. 
While the present invention has been shown to be operable on certain 
off-the-shelf syringes, it may also be adapted or retrofitted to other 
syringes or appliances by the addition of an adapter hub 50 (FIG. 9). 
Adapter hub 50 includes diametrically opposed protrusions 26C adapted to 
ride in groove set 30. Hub 50 may be placed on the barrel of a syringe 
having no other protrusions and may be attached thereto by friction fit. 
Alternatively, hub 50 may be attached to a barrel by induction heating or 
chemical, mechanical or ultrasonic means. The adapter hub 52 shown in FIG. 
10 includes diametrically opposed protrusions 26d and has a central port 
adapted to mate with the Luer-Lok type syringe needle hub. 
Sheath 28 can preferably be injection molded of transparent plastic 
utilizing the collapsible core method as shown and described in U.S. Pat. 
Nos. 3,383,460; 4,019,711; 4,383,819 and 4,533,312; the disclosures of 
which are incorporated herein by reference. 
Having fully described the preferred forms of the invention, it can be seen 
that the objects and advantages of the invention have been achieved. 
Inasmuch as numerous modifications may be made to the preferred 
embodiments, described hereinabove, e.g., projection 40 may be made with 
two camming surfaces similar to projection 38 permitting removal of sheath 
28 prior to use; such modifications do not depart from the spirit and 
scope of the invention. The scope of the invention is to be determined 
solely by the language of the following claims as interpreted in view of 
the Doctrine of Equivalents.