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Description  |
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BACKGROUND
1. Field of The Invention
This invention relates generally to guards used to prevent accidental
contact with the tip of a needle or other skin puncturing device used in
medicine.
2. Background of the Invention
For many years, considerable effort has been devoted to the production of
disposable syringes, catheters, guide wires and other skin piercing
instruments used in the diagnosis and care of medical patients. These
devices have, for the most part, replaced previous systems that included
relatively expensive multiple components used for such purposes and have
eliminated the necessity to resterilize such instruments. Due to their
disposability, such modern syringes, catheters and other devices have been
used extensively in the field for a variety of purposes, including the
injection of medicines, the insertion of intravenous devices and the
drawing of blood and other fluids for analysis. The very disposability of
such devices has resulted in their frequent disposal on the floor or some
other convenient location durinq the course of frantic activity associated
with an emergency room or other life threatening events. Thus, it is not
uncommon for used disposable syringes to be thrown about an emergency room
or other critical care area in which time critical medical care is
occuring.
This littering of a critical care area, such as an emergency room or
intensive care area, with used disposable syringes, with their exposed
needles, creates many possible opportunities for health professionals and
others in the vicinity to come in contact with such needles. As the
technology for producing these needles has improved, they have become
thinner and sharper and thus present a very high probability of skin
penetration in the event that a part of the human body, whether it is
clothed or not, impacts the end of such a needle. While the probability of
infection from such needles has always been present to some degree, the
infection of a significant portion of the population with the Acquired
Immune Deficiency Syndrome (AIDS) virus and the life threatening nature of
this disease to anyone infected with it has heightened concern in the
medical community about such needle penetration. While the exact mechanism
of infection by AIDS is not completely understood, it is well known that
the penetration of the skin by a needle contaminated with blood from a
person infected with the AIDS virus can cause such an infection.
Since there is often insufficient time during most emergency procedures to
screen those being treated for the AIDS virus, there is thus always a
possibility that needles used in critical care areas may be contaminated
with the AIDS virus. Recent documented cases in which health professionals
have been infected by the AIDS virus transmitted through a contaminated
needle has heightened this concern and their exists a need to prevent such
infections if the quality of emergency care is to be maintained.
The very nature of emergency medical treatment prevents comprehensive use
of disposal procedures and the most effective device to accomplish these
requirements would be one requiring no manipulation on the part of the
operator and one which was relatively simple, inexpensive and moderately
foolproof in its operation. Due to the range of procedures which must be
undertaken, it would be useful if any such device would be amenable to
various types of injections such as intramuscular injections, partial
injections, blood drawing and guide wire insertion of catheters. While
safety is the most important aspect of any such a use, it would also be
helpful if such a safety system were also relatively simple and
inexpensive to manufacture.
From the above it may been seen that a serious need exists to protect
health care professionals from accidental contact with contaminated
needles in an emergency room and other emergency medical treatment
environments and that such a safety system should be simple, relatively
foolproof and easily operated.
SUMMARY OF THE INVENTION
The present invention provides a means of eliminating accidental contact
with a needle that has already been used for a medical procedure, thus
reducing the possibility that the needle will accidentally puncture the
skin of a person that comes in contact with a used needle. The invention
also provides a reliable, efficient and inexpensive way of avoiding
accidental puncture of the skin by a used needle of the various types used
in medical procedures.
The construction of the present invention is furthermore relatively
inexpensive to manufacture, is trouble free in operation and reliable in
use and provides the improved security desired without altering the
important characteristics of use of syringes and percutaneous needles in
normal medical procedures.
In a preferred embodiment, the present invention may be configured in the
form of a retractable guard over the needle portion of a medical device
used to pierce the skin, such as a syringe or percutaneous needle. The
guard is positively biased away from the base of the needle and toward the
distal tip by a spring or other suitable elastic means that does not
interfere with the normal functioning of the syringe. When the syringe is
used, the needle is thrust into the skin while the guard is either
withdrawn by the fingers operating at the base of the guard or
alternatively, the act of inserting the needle forces the skin surface to
push the guard away from the needle. Once the syringe is used and the
needle is withdrawn, the spring forces the guard back over the needle,
thereby protecting the needle from further accidental penetration of the
skin of a person coming in contact with it.
The reliable operation of the guard is effected by a V-shaped notch in the
guard in combination with a pin or pins located on the body of a syringe.
When the guard is retracted the pin travels down a first leg of the notch
until its limit is reached and thereafter retracts up a second leg of the
notch after the syringe has been used. The guard is rotated to assure
travel of the pin up the second leg of the notch by means of a torsional
preload on the spring. By retracting up the second leg of the notch, the
pin brings into engagement a locating tab portion of a ratchet on the
guard with a mating serration or plurality of serrations on the body of
the syringe, thereby preventing a second retraction of the guard after its
first use. A slight detent may be placed in the first leg of the V-shaped
notch in order to require a certain amount of positive force to begin the
retraction of the needle guard. A plurality of configurations of notches
may also be used to provide reliable retraction and engagement of the
guard after retraction. Internal guide mechanisms may also be used between
the syringe and the guard to insure accurate and reliable registration of
the guard lock ratchet during and after retraction of the guard.
In another preferred embodiment of the invention, the guard is installed
partially retracted with a conventional hand removeable guard over the
needle. This configuration is adaptable to the "dart-throwing" techniques
used for intramuscular injections, since the needle is partially exposed
prior to use. This embodiment is also useful for partial injections and
other uses in which the needle must be initially exposed before the guard
is actuated. Once the syringe has been used, the guard extends over the
full length of the needle as described above.
Other features and advantages of the present invention will become apparent
from the following detailed description, taken into conjunction with the
accompanying drawings, which illustrate, by way of example, the principals
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a syringe incorporating a first embodiment
of a needle guard according to the present invention.
FIG. 2 is a cross section at 2--2 of FIG. 1, illustrating the internal
relationship of the needle quard with the external configuration of a
syringe incorporating the invention.
FIG. 3 is a cross section of a needle guard and syringe according to the
present invention after the needle guard has been used and has been
returned to its locked position.
FIG. 4 is a cross section at 4--4 of FIG. 2 illustrating the relationship
of the guard ratchet lock prior to use.
FIG. 5 is a cross section at 4--4 after use, retraction and locking of the
needle quard.
FIG. 6 is a cross section at 6--6 of FIG. 2 illustrating the relationship
of the guide pins in slots in the needle guard.
FIG. 7 is an illustration of a needle guard in place on a syringe prior to
its use.
FIG. 8 shows a needle guard at the beginning stage of its retraction.
FIG. 9 shows the needle guard partially retracted as a locating pin travels
down the first leg of the V-shaped notch.
FIG. 10 illustrates the needle guard in its fully retracted position and
the syringe fully depressed.
FIG. 11 illustrates the needle guard in its extended position after use.
FIG. 12 is a perspective view of an alterative preferred embodiment of the
invention for a syringe adaptable for techniques used for intramuscular
injections.
FIG. 13 is a side view of a syringe incorporating the alternative
embodiment prior to use.
FIG. 14 is a side view of a syringe incorporating the alternative
embodiment after the injection has been given.
FIG. 15 is a side view of a syringe incorporating the alternative
embodiment at the maximum stroke of the plunger.
FIG. 16 is a side view of a syringe incorporating the alternative
embodiment after the syringe has been used.
DETAILED DESCRIPTION
While a variety of needle guards have been developed to protect needles
prior to and after their use, such guards have generally been of the type
that must be manually removed and replaced by the person using the
syringe. Although such guards are effective for this use, time and care
can not always be to remove and replace such guards in conditions such as
medical emergencies occuring in an emergency room or other critical care
area, where the full attention of the doctors, nurses and technicians must
be directed to rapid care of the patient.
The present invention provides a reliable and efficient means of protecting
medical personnel and others prior to and after the use cf such a syringe,
thus preventing unnecessary exposure to blood transmitted diseases such as
AIDS or other contaminants that might otherwise enter the blood stream if
a used needle were contacted.
As illustrated in the exemplary drawings, a first preferred embodiment of
the invention includes an essentially tubular needle guard that is held
over the needle by a spring acting between a shoulder on the needle guard
and a shoulder on the body of the syringe. Pins are mounted on the body of
the syringe and protrude through slots located on the needle guard that
provide, in combination with a torsional preload in the spring, the means
of guiding the needle guard in a predictable manner during its retraction,
which occurs when the syringe is used. The pins also serve to prevent the
tubular guard from being pushed off of the end of the syringe by the
spring. The retraction of the needle guard can either be accomplished by
the operator of the syringe pulling the needle guard away with his fingers
on the shoulder of the needle guard, or by pushing the syringe downward
towards the skin of the patient, thereby retracting the needle guard as
the needle pierces the skin. The slot in which the guide pin rides is
essentially V-Shaped, with the point of the V located distally, and serves
to rotate the needle guard through an angle of approximately 90 degrees
during retraction and release to thereby engage a one way ratcheting
mechanism with its component parts located on the inside of the needle
guard and the outside of the syringe. When the needle guard is released
and allowed to move over the needle, rotating the mechanism and engaging
the ratchet, the guard thereby prevents another retraction or a further
retraction of the needle guard.
A second preferred embodiment is adapted for use in intramuscular
injections or other injections that utilize the "dart-throwing" technique,
in which the syringe is rapidly flicked by the wrist to quickly and deeply
insert the needle. This second preferred embodiment is also adaptable to
partial injections and other uses where it is desireable to have the
needle partially exposed, with only a conventional guard in place, in the
initial configuration prior to the actuation of the guard. This second
embodiment is configured with the cylindrical guard partially retracted.
Thus, the first leg of the notch is shorter than the second leg and a
conventional needle guard is used to prevent contamination of the needle
prior to use. When the syringe is used, the operation of the guide is as
described above, with suitable changes in the geometry of the slot and
ratchet lock to accomodate the different initial stroke.
Thus, it may be seen that the present invention provides a simple,
inexpensive and reliable means of preventing the reuse of a needle and
also prevents any further contact with the tip of the needle once it has
been used, thus substantially enhancing the safety of medical personnel
and reducing the probability that they will come in contact with
contaminated needles in a hospital environment.
FIG. 1 is a perspective illustration of a needle guard attached to a
syringe according to a first embodiment of the present invention. The
needle guard, generally designated 4, is an attachment to a conventional
syringe 2 that has certain modifications which improve the operation of
the needle guard. The tubular guard 6 is sized to retract over the barrel
8 of the syringe 2 when the guard 4 is retracted. A conventional needle
protector 10 is removed prior to the time that the syringe is to be used.
In practice, it may be advantageous to provide needle protector 10 with an
extension 12 which reaches beyond the distal opening 14 and tubular guard
6 in order to assist in removal of the needle protector 10. After the
needle protector has been removed, the syringe is used by retracting
tubular guard 6 over the body of syringe 8 against the pressure exerted by
spring 16 operating against the shoulder 18 of the proximal end of barrel
8, the spring also bearing against the shoulder 20 and tubular guard 6. At
least one pin 22 extends through a slot 24 in tubular guard 6. As the
guard is retracted, pin 22 is moved past a detent 26 formed as a slight
narrowing of the width of the slot before moving down the first leg 28 of
the V-Shaped slot 24. Detent 26 is configured to help prevent accidental
initial retraction of the needle guard and requires a positive force on
the part of the operator to initialize retraction of tubular guard 6. .s
the guard is retracted, pin 22 guides the tubular guard 6 through
approximately 90 degrees of rotation until the proximal extremity of slot
24 is reached at the end of the first slot 28.
Thereafter, the syringe is used and its contents ejected by depressing
plunger 30 to force it through the needle. After the contents have been
expelled, pin 22 guides tubular guard 6 to its deployed position by
traveling through slot 32 until it reaches its fully deployed position. At
that time, a ratchet mechanism, generally designated 34, is engaged to
prevent a subsequent withdrawl of the tubular guard 6 from the needle.
From the above description in may be seen that the present invention
accomplishes the important functions of preventing inadvertent contact
with the needle both before and after its use in a medical procedure and
is simple to operate, inexpensive and mechanically simple in its
configuration, and has a high reliability of operation under emergency or
other stressful medical procedures.
Illustrated in FIG. 2 is a cross sectional view of the guard in its initial
position prior to the first retraction. As illustrated, tubular guard 6 in
the deployed position has a proximal opening 14 that extends beyond needle
guard 10 except for the extension 12. Alternatively, needle protector 10
may be extended to allow easier removal of the needle protector prior to
use without initial retraction cf needle guard 4. As the tubular guard 6
is retracted, pins 22 and slots 24 guide tubular guard 6 through ar
approximately 90 degree rotation to bring the components of ratchet
assembly 34 in registration with one another prior to the release of the
guard. Ratchet arm 36 on the body of the needle guard, when retracted, is
in registration with ratchet teeth 38 on syringe boyd 8 after the guard is
fully retracted and the syringe is empty so that further movement of body
6 in the direction of the deployed position of the guard, assisted by
spring 16 acting against shoulder 18, brings the elements of ratchet 34 in
registration with one another, thereby preventing any subsequent
retraction of the guard. The rotation of guard 6 as pin 22 travels down
slot 28 and back up slot 32 is assisted by a torsional preload in spring
16 and appropriate spring indexing devices in shoulders 18 and 20. Initial
retraction of the guard is inhibited by detent 26 in slot 28 in
combination with pin 22.
FIG. 3 illustrates the arrangement of ratchet mechanism 34 after a needle
protector has been removed and the syringe has been used, with the
subsequent exposure of needle 40. Tubular guard 6 has now traveled to its
deployed position with the proximal opening 14 extending beyond needle 40.
Meanwhile, the ratchet arm 36 has come into engagement with ratchet teeth
38 on the syringe body 8 in response to the force exerted by spring 16
against shoulder 20. The resulting ratcheting action prevents subsequent
withdrawal of tubular guard 6 after it reaches its deployed position.
FIG. 4 is a cross section at 4--4 of FIG. 2 and illustrates the arrangement
of ratchet arm 36 on guard 6 and ratchet teeth 38 on syringe body 8 prior
to initial use of the guard. While an angle of 90 degrees is illustrated,
those skilled in the art will appreciate that other angles to accomplish
the same registration of the ratchet mechanism after use may be used.
FIG. 5 illustrates the arrangement of ratchet arm 36 and ratchet teeth 38
after the use of the syringe, showing that such registration engages the
teeth 38 in syringe body 8 with the ratchet arm 36 and tubular guard 6.
FIG. 6 illustrates the arrangement of pins 22 in the first leg 28 of slot
24 formed in tubular guard 6. In this view, the second leg 32 of the slot
24 is illustrated as terminating in a position of 90 degrees to the
initial position of slot 28. Pins 22 are mounted in the body 8 of syringe
2, thus providing a positive guide for the travel of the guard as it is
retracted and deployed.
FIGS. 7 through 11 illustrate the use of the guard during the typical
medical use of a syringe. FIG. 7 illustrates the tubular guard 6 in its
initial undeployed position, showing that detent 26 prevents initial
movement of tubular guard 6 unless enough force is exerted to overcome
both the action of spring 16 against shoulder 20 and the force required to
move pin 22 past detent 26 into the first portion of slot 28. Also
illustrated is a means of torsionally retaining spring 16 against shoulder
20. In this embodiment spring 16 has a portion 44 that is bent parallel
with the axis of the spring and engages a notch 46 in shoulder 20. Spring
16 can be installed with a torsional preload that forces the guard to
rotate in the direction of slot 32, thereby assuring that the guard will
latch in its safe position after use.
FIG. 8 further illustrates the arrangement of spring 16 acting against both
shoulder 20 on tubular guard 6 and shoulder 18 on syringe 2 prior to
either the movement of tubular guard 6 or the depression of plunger 30.
FIG. 9 illustrates the initial stage of use of the syringe and guard
showing that pin 22 has now moved past detent 26 and down the first leg 28
of V-shaped slot 24. Spring 16 has been partially compressed between
shoulders 18 and 20 and plunger 30 has been partially depressed, thereby
expellinq a portion of the contents of the syringe through needle 40,
which is now penetrating the skin cf the patient.
FIG. 10 illustrates a guard and syringe according to the present invention
in its fully deployed and fully expelled position. Spring 16 has been
fully compressed between shoulders 18 and 20 and the entire contents of
the syringe have been expelled due to the full depression of plunger 30.
Pin 22 has traveled to the extreme limit of the V-shaped slot 24, and
tubular guard 6 is fully retracted. If a guard according to the present
invention where not used, this would be the condition of a used syringe
not protected with a guard and the full length of the needle would be
exposed, thereby substantially increasing the risk that there would be an
accidental penetration of the skin of a person coming into contact with a
syringe.
FIG. 11 illustrates the position after use of the syringe and redeployment
of the guard as forced by spring 16 acting between shoulders 18 and 20.
Pin 22 has now traveled up the second leg 32 of V-shaped slot 24, thereby
engaging the ratchet 34 consisting of ratchet arm 36 and teeth 38. In this
position the syringe needle is completely protected by the deployment of
the guard and the distal opening 14 of the guard projects a distance
beyond the tip of needle 40.
Illustrated in FIG. 12 is a second preferred embodiment of the invention
that is adapted to the so-called "dart-throwing" technique for
intramuscular injections. This technique utilizes a flip of the wrist to
rapidly thrust the needle of a syringe into the skin of a patient. The
technique is particularly effective if a dense mass of tissue such as
muscle is to be injected. In order to assist this process, it is
desireable that there be a portion of the needle initially exposed so that
the needle guard does not impede the insertion of the needle and the
spring does not cause a rebounding of the needle after insertion. In this
embodiment, needle guard 6' is installed so that is is partially
retracted, thereby exposing a conventional interior needle guard 10' The
first leg 28' of slot 24' is shorter than second leg 32' by the required
amount to accomodate the initial retracted portion of the full stroke of
the needle guard 6'. A detent 26' is used as described above to prevent
movement of the guard prior to depression of the plunger to expeed the
contents of the syringe. In this embodiment, a smaller opening 14' in the
distal end of guard 6' is shown to illustrate the guard may be configured
to prevent the intrusion of even a small finger into the guard after its
use. Also illustrated is an alternative configuration of shoulder 18' in
which a cylindrical housing 42 is used to both retain the spring 16' and
limit the travel of guard 6' thereby placing less stress on pins 22' which
would otherwise be used to limit the stroke of the guard. A further
important use for shoulder 42 is to prevent the use of a guarded syringe
as a conventional syringe by grasping shoulder 42 and pressing plunger
30'. Since the design of shoulder 42 offers no purchase, the user is
forced to use shoulder 20' and plunger 30', thereby utilizing the guard
6'. Thus, the configuration of shoulder 42 provides an additional safety
feature in forcing the user to engage the guard.
FIG. 13 further illustrates the arrangement of spring 16' acting against
both shoulder 20' on tubular guard 6' and shoulder 18' or syringe 2' prior
to either the movement of tubular guard 6' or the depression of plunger
30'.
FIG. 14 illustrates the initial stage of use of the syringe and guard
showing that pin 22' has now moved past detent 26' and down the first leg
28' of V-shaped slot 24'. Spring 16' has been partially compressed between
shoulders 18' and 20' and plunger 30' has been partially depressed,
thereby expelling a portion of the contents of the syringe through needle
40', which is now penetrating the skin of the patient.
FIG. 15 illustrates a guard and syringe according to this embodiment of the
present invention in its fully deployed and fully expelled position.
Spring 16' has been fully compressed between shoulders 18' and 20' and the
entire contents of the syringe have been expelled due to the full
depression of plunger 30'. Pin 22' has traveled to the extreme limit of
the V-shaped stop 24', and tubular guard 6' is fully retracted. If a guard
according to the present invention where not used, this would be the
condition of a used syringe not protected with a guard and the full length
of the needle would be exposed, thereby substantially increasing the risk
that there would be an accidental penetration of the skin of a person
coming into contact with a syringe.
FIG. 16 illustrates the position after use of the syringe and redeployment
of the guard as forced by spring 16' acting between shoulders 18' and 20'.
Pin 22' has now traveled up the second leg 32' of V-shaped slot 24',
thereby engaging the ratchet 34' consisting of ratchet arm 36' and teeth
38'. In this position the syringe needle is completely protected by the
deployment of the guard and the distal opening 14' of the guard projects a
distance beyond the tip of needle 40'.
From the above it may be seen that the present invention represents a
substantial improvement in the protection of used needles of hypodermic
syringes and other skin penetration apparatus which may be used in medical
procedures and which may have been contaminated during the course of that
use. Furthermore, the invention is easily implemented on otherwise
conventional syringe designs and is relatively simple and economical in
its use. The invention is particularly advantageous for emergency room and
other difficult medical environments since it requires no special
procedures or skills on the part of the user.
While a particular form of the invention has been illustrated and
described, it will also be apparent to those skilled in the art that
various modifications can be made without departing from the spirit and
scope of the invention. Accordingly, it is not intended that the invention
be limited except as by the appended claims.
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