Free-standing safety cap for permanently storing contaminated medical instruments

A free-standing safety cap for storing contaminated medical instruments includes a sleeve, a stand on one end of the sleeve and a one-way locking mechanism on the other end. A user places the cap on a flat surface so that it is free standing and, without grasping the cap, inserts the instrument's contaminated sharp end into the cap. The one-way locking mechanism permanently secures the contaminated sharp end inside the cap. The stand can be formed with an opening for accessing the sleeve so that the cap can used for storing both the sterile and the contaminated instrument. This greatly reduces the risk of accidental puncture wounds to the cleaning and waste disposal personnel.

RELATED APPLICATION 
This application is related to application Ser. No. 08/345 611 entitled 
"Safety Cap and Hub for Medical Instruments" filed Nov. 28, 1994 now U.S. 
Pat. No. 5,554,129 by the applicant of the present invention. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to the storage and disposal of 
sharp medical instruments such as contaminated hypodermic needles, and 
more specifically to a safety cap for use with a complementary instrument 
hub such as a conventional needle hub or scalpel blade holder. 
2. Description of the Related Art 
Hypodermic needles are used to give injections and draw blood from 
patients. These needles can become contaminated with any number of 
infectious and potentially lethal diseases. Other medical instruments such 
as scalpels can become similarly contaminated. The threat of accidental 
puncture wounds from contaminated needles or scalpels poses a significant 
safety risk to medical personnel, hospital cleaning staff, waste disposal 
workers and the general public. 
Until the early 1980's, it was standard practice to "recap" a needle after 
use. This required the user to grasp the narrow plastic'sleeve in one 
hand, and with the other hand insert the contaminated needle into the 
sleeve. These sleeves were designed primarily to provide physical 
protection for the needle and to maintain sterility before use. Because of 
the sleeve's size and shape, a user could very easily miss the sleeve and 
puncture his or her hand. Furthermore, the cap could be accidentally or 
intentionally removed, thereby exposing the contaminated needle. 
The medical community recognized this danger and adopted a policy against 
recapping. Instead, medical treatment areas are supposed to be equipped 
with special "sharps containers" for disposing contaminated sharp objects 
such as hypodermic needles or scalpels. These containers are typically 
fitted with either flexible plastic flaps or fixed baffles over their 
openings. The flaps are formed from a plastic diaphragm which has a hole 
at its center with slits extending radially outward from the hole. These 
designs are supposed to allow contaminated objects to be pushed through 
the opening, but prevent them from falling back out of the container. As a 
practical matter, sharps containers cannot be provided immediately 
adjacent every location where injections are being given, blood is being 
drawn or incisions are being made. Therefore, the user must carry the 
exposed contaminated needle or scalpel some distance before disposing of 
it. Furthermore, the sharp instruments have managed to back out of the 
container's opening or poke through its walls, posing a significant safety 
risk. 
U.S. Pat. No. 4,883,470, "Safety Cap", discloses a flared cap for storing 
the needle and cannula hub before and after use. The cap and cannula hub 
have complementary rib designs which allow a syringe to both engage the 
hub and remove the needle from the cap prior to use, and to reinsert the 
contaminated needle into the cap and disengage the syringe. The flared cap 
reduces the risk of self-puncture, but the user must still grasp the cap 
with his off hand to recap the needle. Furthermore, the recapped 
contaminated needle can be withdrawn from the cap by reengaging a syringe. 
U.S. Pat. No. 5,026,345, "Non-Mechanical Incapacitation Syringe Safety 
Needle Guard", discloses an enlarged flange for guiding a contaminated 
needle into a long narrow sheath to prevent the user from puncturing his 
hand during insertion. The insertion of the needle into the guard 
punctures a membrane thereby releasing an adhesive that permanently seals 
the contaminated needle inside the guard. 
U.S. Pat. Nos. 4,846,811, 4,874,384, 5,342,309 and 5,053,018 disclose 
slidable or telescoping sleeves that fit over the syringe. The sleeves are 
retracted to expose the needle, and then slid down and locked to shield 
the tip. These syringes are awkward to use due to the extra bulk on the 
syringe itself. Furthermore, the incorporation of moveable parts increases 
the cost and reduces the reliability; moving parts break. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide a simple and cost effective safety 
cap that will allow the user to permanently store a contaminated sharp 
instrument in the safety cap without having to grasp the cap to insert the 
used instrument. 
This is accomplished with a free-standing safety cap with a sleeve for 
permanently securing the used sharp instrument, such as hypodermic needle 
or scalpel blade. The safety cap is designed to work with a needle which 
is mounted in a plastic hub, such as a standard conventional hypodermic 
needle, or with a needle which may be mounted directly in a syringe, such 
as, for example, a standard conventional insulin syringe with needle. In 
the case of a scalpel blade, the device is designed to work with a blade 
which is affixed in a disposable plastic handle. A stand supports the cap 
in a position in which an opening into the sleeve is exposed to receive 
the used sharp instrument. This opening is fitted with a one-way locking 
mechanism, which will allow the plastic hub, or base, syringe or handle to 
slide into the opening, and will lock onto the plastic part and securely 
prevent it from being pulled back out. The syringe can be optionally 
disengaged from the captured contaminated needle. 
Three different alternative configurations are envisioned for the safety 
cap. In the simplest configuration, the cap has a single sleeve and a 
single opening into that sleeve, for receiving the contaminated sharp 
instrument. In practical use, this type of safety cap would typically be 
supplied separate from the needle or other sharp instrument which it is 
designed to contain. Safety caps of this type could be supplied 
non-sterile, in bulk packaging, for use at the treatment site to quickly 
and easily contain the contaminated sharp instrument and render it 
harmless to the user or others. 
In a second configuration, the safety cap may be supplied with a second 
sleeve, also having a single opening but without a locking mechanism; this 
sleeve is intended to contain the sterile instrument prior to use. In 
practical application, this type of safety cap would be supplied together 
with the sterile sharp instrument in a single package, with the needle or 
other sharp instrument stored within the second sleeve prior to use. 
In the third configuration, the safety cap has only a single sleeve which 
is intended to contain the sharp instrument both before and after use. As 
described above, the sleeve has an opening with a locking mechanism for 
securely containing the used sharp instrument. In addition, the same 
sleeve has a second opening which does not have a locking mechanism, and 
typically opens into the opposite end of the sleeve from the locking 
opening. In practical application, this type of safety cap would also be 
supplied together with the needle or other sharp instrument in a single 
package. Prior to use, the sterile needle would be supplied with the 
needle inserted into the non-locking opening for storage of the needle 
with the sleeve prior to use. The length of the sleeve is such that the 
sharp object is sufficiently recessed below the unused opening in the 
opposite end, to prevent contact with a finger or any other body part of 
the user. After use, the contaminated sharp instrument is inserted and 
locked into the locking end of the same sleeve. Again, the length of the 
sleeve provides sufficient recess of the sharp object below the opening in 
the opposite end, to prevent human contact. As compared to the safety cap 
configuration which has two sleeves, this third configuration has the 
advantage of smaller size, but has the disadvantage that the tip of the 
used sharp instrument is not completely enclosed within the sleeve, but is 
protected by it's recessed position. 
For a better understanding of the invention, and to show how the same may 
be carried into effect, reference will now be made, by way of example, to 
the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The invention provides a free-standing safety cap design for use with a 
conventional instrument hub or handle that reduces the risk of accidental 
puncture wounds for contaminated sharp medical instruments such as 
hypodermic needles and scalpels. The user places the cap on a flat surface 
so that it is free standing and inserts the contaminated instrument 
without grasping the cap. The cap allows the user to permanently secure 
the contaminated instrument without having to grasp the cap in his or her 
off hand until after the contaminated instrument is safely captured inside 
the cap. Furthermore, the cap provides a one-way locking mechanism that 
permanently secures the sharp end of the contaminated instrument inside 
the cap. This greatly reduces the risk of accidental puncture wounds to 
the cleaning and waste disposal personnel. The safety cap is described 
with respect to the standard hypodermic needle and plastic needle hub that 
are currently used in the medical profession, but is applicable to other 
types of sharp medical instruments. 
FIG. 1 is a partially exploded view of a syringe 10 and a hypodermic 
needle-hub assembly 12 including a needle 14 attached to a hub 16. A 
conventional needle cap 18 is used to protect the sterile needle 14. After 
use, a free-standing safety cap 20 captures and permanently secures the 
contaminated needle 14. A one-way locking mechanism such as a spring clip 
22 locks the needle hub 16 in place thereby preventing the contaminated 
needle 14 from being pulled back out of the safety cap 20. 
The hypodermic syringe 10 and the needle-hub assembly 12 are preferably 
supplied in sterile packages, either separately, or assembled together as 
a single unit. The sterile needle is preferably supplied with a disposable 
conventional needle cap 18 which is not intended to be used for recapping 
the needle because of risk of self-puncture. The free-standing safety cap 
20 may either be supplied together with the needle-hub assembly in the 
same sterile package, or it may be supplied separately in which case it 
need not be sterile. 
To give an injection or draw blood, the user removes the sterile syringe 10 
and needle 14 from the sterile package and attaches the syringe to the 
needle-hub assembly 12, with the sterile conventional needle cap 18 still 
covering the needle 14. The safety cap 20 is placed on a flat surface, 
such as a counter top or bedside table, adjacent to the treatment site. 
The bottom of the safety cap 20 may be coated with adhesive to help 
prevent tipping. Just prior to using the hypodermic assembly, the sterile 
conventional needle hub is removed and may be discarded. 
Once the needle has been contaminated, the user, holding the syringe, 
inserts the used needle into an opening in the spring clip 22 at the upper 
end of the safety cap 20, and pushes the needle down into the cap until 
the plastic needle hub 16 engages into the jaws of the spring clip 22. The 
user's free hand is kept clear, and some distance away, during this 
procedure. The cap 20 with needle enclosed inside may then be disposed of, 
either with or without the syringe attached. 
As shown in FIG. 2, the standard Luer-Lock hub 16 of the type manufactured 
by Becton-Dickinson includes a flange 24, which is configured to thread 
into a threaded female Luer-Lock connector such as found on a syringe. A 
tapered section 26 with an internal hollow tapered cylinder designed to 
press fit over the nipple part of a female Luer-Lock connector is affixed 
to the flange 24. A smaller diameter cylindrical section 28 extends from 
the tapered section 26 with projecting vanes 30 which may engage 
complementary vanes or projections inside the needle cap to prevent the 
needle-hub assembly from rotating within the cap 18 shown in FIG. 1, and 
thereby facilitate connection of the needle-hub assembly to a syringe or 
other Luer-Lock device. 
As shown in FIG. 3, the safety cap 20 includes a plastic or polymer bottom 
section 32 and the spring metal clip 22. The spring metal clip is 
comprised of a curved oval outer section 34, which supports a plurality of 
downward projecting teeth 36. The teeth form an opening 38 for receiving 
the needle hub, and the teeth are designed to allow easy insertion of the 
needle hub but to prevent it from being pulled back out. The plastic 
bottom section 32 includes a flat base 40, of sufficient size to allow the 
safety cap 20 to rest stably on a flat surface, and to prevent the safety 
cap from tipping when a needle and hub are inserted into the metal clip. 
The bottom of the base 40 may be coated with adhesive to improve 
stability. 
A plastic or polymer sleeve 42 is affixed to the flat base 40 to receive 
and permanently contain the used needle or other sharp instrument. The 
sleeve 42 must be wide enough and tall enough to store the contaminated 
needle or instrument for which it is specifically designed. Typically the 
sleeve 42 is much taller than it is wide. For example, a sleeve for a 
standard hypodermic may be approximately 4 cm tall and 1.3 cm wide. As a 
result, unless the sleeve is made unnecessarily wide, it could not rest 
stably on the flat surface without the base 40. 
A fastening mechanism 44 is provided at the other end of the sleeve 42 to 
securely fasten the spring metal clip 22 to the sleeve. As illustrated 
here, the fastening mechanism 44 consists of two plastic tabs which 
project upward through holes in the spring metal clip 22, and which are 
fused downward at the time of manufacture. A variety of alternative 
fastening mechanisms could be used. The sleeve 42 can have many different 
cross-sectional shapes; it may be polygonal, round, or oval, or any of a 
number of other shapes. Reinforcing struts 46 may be provided to 
strengthen the unit and provide added rigidity to the flat base. 
As shown in FIGS. 4a and 4b, the spring clip 22 is preferably formed of 
spring steel or another resilient metal which will tend to return to it's 
original shape when it has been deformed. As shown here, the metal clip 
comprises an oval outer section 34, which has a gentle downward curvature, 
and two downward projecting metal teeth 36. The space between the downward 
projecting teeth forms an opening 38 into which the needle hub may be 
inserted, and locked. The spring metal clip is also perforated by two 
holes 48 which are used to firmly secure the clip to the plastic bottom 
piece of the safety cap. This is accomplished with two complementary 
plastic or polymer tabs which project up from the bottom piece of the 
safety cap, and are melted or sonically fused at the time of manufacture 
to form a knob of plastic above the holes in the metal clip, of diameter 
greater than the holes, to effectively prevent the metal clip from 
separating from the plastic bottom piece. This design represents only one 
possible fastening mechanism; it is envisioned that a variety of different 
fastening mechanisms could be used. 
As shown in FIGS. 5a and 5b, the plastic or polymer bottom piece 32 of the 
safety cap 20 includes the sleeve 42 that is affixed to the flat base 40 
and projects upward and is open at the top. The upper end 50 of the sleeve 
is designed with a complementary shape to the curved spring metal clip and 
is provided with two upward projecting plastic tabs 52 which fit through 
complementary holes in the spring metal clip. Following assembly of the 
metal clip onto the bottom piece, these plastic tabs are melted or 
sonically fused to secure the metal clip to bottom piece and prevent it 
from being pulled off. Vanes 46 may be provided to strengthen the 
structure. 
FIG. 6a is a cross sectional view of the plastic needle hub assembly 12 as 
it is pushed down into the spring metal clip 22. The needle hub is 
inserted into the opening 38 formed between the metal teeth 36. As the 
tapered upper part 26 of the needle hub is forced downward, the metal 
teeth 36 of the spring metal clip are bent progressively downward and 
farther apart, in the direction shown by arrow 54. 
FIG. 6b shows a cross sectional view of the plastic needle hub 12 after it 
has been pushed sufficiently far into the metal clip 22 to become engaged 
within the clip. The spring metal teeth 36, attempting to return to their 
original conformation due to the resilience of the spring steel, will 
resist the downward and outward pressure from the needle hub, and will 
exert a counter pressure on the hub in an upward and squeezing direction, 
shown by arrow 56. This will cause the metal teeth 36 to form an 
indentation in the deformable plastic of the needle hub and they will 
engage the hub, preventing it from sliding back out from the opening 
between the teeth. If an effort is made to pull the needle hub back out 
from between the spring metal teeth by pulling upward on the needle hub in 
the direction illustrated by arrow 58, the metal teeth 36 are drawn closer 
together, in the direction shown by arrow 56, thus engaging the needle hub 
more firmly, and preventing it from being pulled back out. 
An alternate embodiment of the safety cap's spring clip is shown in FIG. 7. 
This design uses a smaller spring metal clip 60 which is annular in shape, 
with four downward projecting metal teeth 62. The metal teeth 62 function 
in the same way to engage the plastic needle hub, as the metal teeth 36 
function in the metal clip design illustrated in FIGS. 4a and 4b. The 
safety cap comprises a plastic or polymer base 64 of essentially the same 
cross-sectional shape as the base shown in FIG. 3, with the spring metal 
clip 60 being molded into the sleeve 66 at the time of manufacture. This 
safety cap design also differs from the design shown in FIGS. 5a and 5b, 
in that the sleeve 66 is this design preferably has a circular 
cross-section. 
FIGS. 8a, 8b and 8c show three alternative configurations for the safety 
cap with respect to the arrangement of an opening for containing the 
needle or sharp instrument after use, and, in the case of FIGS. 8b and 8c, 
an additional opening for securing and protecting the sterile needle prior 
to use. 
FIG. 8a shows a cut-away perspective view of the safety cap design 20 that 
was illustrated in FIGS. 1 through 5. This safety cap design has a single 
sleeve 42 for containing a used needle, and a single opening 38 which is 
supplied with a locking mechanism 22 for receiving the needle hub and 
preventing it from being pulled back out of the sleeve. 
FIG. 8b shows a cut-away perspective view of an alternate embodiment of a 
safety cap 68. This safety cap comprises a plastic or polymer bottom piece 
70 that is molded to define a sleeve 72 for receiving the used 
contaminated sharp instrument. The sleeve 72 is equipped with a metal clip 
74 for securing the used needle hub and preventing it from being pulled 
back out. The bottom piece 70 is molded to define an additional sleeve 76 
with an opening 78, which preferably opens into the base 80 of the safety 
cap, for the purpose of securing and protecting the sterile needle and hub 
prior to use. 
The inner shape of the sleeve 76 is essentially the same as that of a 
conventional needle cap that is currently manufactured and supplied with a 
typical needle-hub assembly. The inner surface of sleeve 76 is formed with 
a plurality of inward-projecting ridges 80 which serve the purpose of 
engaging the vanes 30 of the conventional needle hub (shown in FIG. 2) to 
prevent rotation of the hub within the sleeve and allow the user to firmly 
secure the needle hub to a syringe by screwing it into the female 
Luer-lock connector on the end of the syringe. 
The safety cap design shown in 8b replaces the function of both the 
conventional cap 18 and the safety cap 20 as shown in FIG. 1. The safety 
cap 68 will be provided in a sterile package from the manufacturer with 
the needle-hub assembly inserted into sleeve 76 via opening 78. The 
sterile package may also contain, optionally, a sterile syringe attached 
to the needle hub. To give an injection or draw blood, the user breaks the 
sterile seal, removes the needle and cap assembly and attaches the needle 
hub to a syringe if not already supplied with syringe attached. The user 
then removes the needle from the safety cap for use, and places the safety 
cap on a stable flat surface adjacent to the treatment site. The safety 
cap is placed with the flat base 81 down and the opening 82 to sleeve 72 
pointing upward with the metal clip 74 exposed. 
Once the needle has been contaminated, and with his other hand held at a 
distance away from the safety cap, the user inserts the used needle 
through the opening in the metal clip 74 into the sleeve 72 and pushes the 
needle down until the hub is engaged into the metal clip. The safety cap 
with needle and hub is then disposed of as a unit, either with, or without 
the syringe attached. 
FIG. 8c shows a cut-away perspective view of another embodiment of a 
free-standing safety cap 84. This safety cap design comprises a plastic or 
polymer bottom piece 86 that is molded to form a sleeve 88 that is affixed 
to a flat base 90. The sleeve 88 has an opening 92 opposite the flat base 
90 that is surmounted by a metal clip 94. The sleeve 88 has an opening 96 
in the base 90 and is provided with inwardly projecting ridges or vanes 98 
towards that end. These vanes are positioned and shaped so as to provide a 
snug fit to a conventional syringe hub such as shown in FIG. 2, and also 
to interlock with the vanes 30 on the syringe hub to prevent it from 
rotating within the sleeve. The metal clip 94 is designed to allow the 
easy insertion of needle and hub and to engage the plastic hub to prevent 
it from being pulled back out. 
The safety cap 84 shown in FIG. 8c is used in the same manner as the safety 
cap 68 shown in FIG. 8b. The design shown in 8c differs from that shown in 
8b, in that only one sleeve is used in 8c, to contain the sterile needle 
before use, and to contain the contaminated needle after use. This is 
accomplished through the provision of two separate openings into the 
sleeve 88. The top opening 92, opposite the base 90, is provided with a 
mechanism 94 to prevent the contaminated needle from being pulled back 
out, while the opening 96 which opens through the base 90, is fitted with 
a mechanism 98 to prevent the needle hub from rotating axially in the 
sleeve, and allows the needle and hub to be withdrawn and reinserted at 
will. The bottom piece of the safety cap is designed to provide a sleeve 
88 of sufficient length that the tip of the needle, when inserted into 
either end of the sleeve, will be sufficiently recessed back from the 
opening in the opposite end of the sleeve to prevent contact with a finger 
or any other body part of the user or any other person who may come into 
contact with the safety cap, such as waste disposal personnel, 
housekeeping personnel, etc. 
The safety cap designs shown in 8a, 8b and 8c may also be modified by 
replacing the spring metal clip with a plastic clip 100 as shown in FIGS. 
9, 10a and 10b. The plastic clip comprises a funnel shaped rim 102 with a 
flexible center opening 104. The flexible opening 104 is provided with a 
plurality of flexible flanges 106. The flanges are made by forming radial 
slots 108 in the rim that are spaced around the opening 104 and extend 
outward from the opening. The flexibility of the flanges is increased by 
forming linear notches 110 in the underside of the plastic clip. The 
plastic clip 100 is designed to work not with a conventional needle hub 
such as shown in FIG. 2, but with a locking needle hub assembly shown in 
FIGS. 11 and 12. 
As shown in FIGS. 11a and 11b, the locking needle hub preferably comprises 
a hollow shaft 112 that is attached to needle 114. The opposite end 116 of 
the shaft is formed with an internal taper 118. The end 116 is provided 
with a Luer-lock flange 120 for connection to a conventional Leur-lock 
fitting on a syringe. The one-way locking mechanism is preferably a 
tapered stop 122 formed around the shaft 112. The stop's narrow end 124 
faces the needle 114 and its base 126 faces the end 116 of the shaft. The 
ridge formed by the base is capable of engaging the plastic flanges 106 
when the hub is inserted into the plastic clip 100 shown in FIGS. 10a and 
10b, thereby preventing the hub and needle from being pulled back out of 
the clip. 
As shown in the perspective view of the locking needle hub, FIG. 12, the 
needle hub is also provided with a plurality of plastic wings 128, 
preferably 2. These wings perform substantially the same function as the 
vanes 36 on a conventional needle hub as shown in FIG. 2, to engage with 
complementary ridges within the needle cap to prevent the needle hub 
assembly from rotating within the cap. In addition, these wings can engage 
with the slots 108 in the plastic or polymer clip assembly shown in FIGS. 
10a and 10b, to prevent the used needle hub from turning within the safety 
cap and thus allow disengagement of the syringe from the used needle hub. 
The bottom piece design shown in FIG. 8c, having a single sleeve with two 
openings, when provided with a plastic or polymer clip similar to 100 in 
FIGS. 9 and 10, results in a design in which the clip and bottom piece may 
all be molded together in a single injection mold. This will reduce the 
production cost of the unit by eliminating the need to mold the bottom 
piece and the clip separately and then fuse them together. 
The described safety cap designs reduce the risk of accidental puncture 
wounds. The free-standing safety cap receives the contaminated needle or 
scalpel without requiring the user to hold onto the cap, and thus reduces 
the risk of self-puncture wounds. Once the needle or blade is reinserted, 
it is permanently secured inside the cap; this reduces the risk to 
personnel charged with disposing of the contaminated instruments. 
While several illustrative embodiments of the invention have been shown and 
described, numerous variations and alternate embodiments will occur to 
those skilled in the art. Such variations and alternate embodiments are 
contemplated, and can be made without departing from the spirit and scope 
of the invention as defined in the appended claims.