Abstrict A single-use disposable syringe. In the syringe, a reservoir is
formed of two sheets of thermoplastic material having expanded central
portions that form a pair of convex domes. Both of the domes are
compressible, and a connecting member spaces apart the domes. In
response to complete compression of both of the central portions
together, the reservoir substantially collapses and each of the
domes becomes concave to prevent the reservoir from being reformed
and to prevent reuse of the syringe. After partial compression of
both of the central portions together and partial collapse of the
reservoir, the central portions expand to reform the reservoir and
draw fluid into the reservoir, thereby aspirating a hypodermic needle.
Claims What is claimed is:
1. A single-use disposable syringe for providing a medicament for
injection into a patient, the syringe comprising:
needle assembly means for injecting the medicament into the patient;
and
reservoir means for storing the medicament and for expelling the
medicament into the needle assembly means, the reservoir means including
two sheets of thermoplastic material, wherein each of the two thermoplastic
sheets is comprised of an expanded central portion, an expanded
injection neck portion, an expanded filling neck portion, and a
substantially flat peripheral portion,
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are opposite and coextensive to
each other and are sealed together face-to-face, and the expanded
central portions are opposite and coextensive to each other, to
form a reservoir for storing the medicament,
in which the expanded injection neck portions extend from the expanded
central portions to a first end of each sheet, and are opposite
and coextensive to each other, to form an injection port extending
from the reservoir and connected to the needle assembly means for
directing the medicament from the reservoir to the needle assembly
means, and
in which the expanded filling neck portions extend from the expanded
central portions to a second end of each sheet, and are opposite
and coextensive to each other, to form a filling port extending
from the reservoir for filling the reservoir with the medicament;
wherein the expanded central portions are compressible, and in
response to complete compression of both of the central portions
together, the reservoir substantially collapses to prevent the reservoir
from being reformed and to expel the medicament out of the reservoir;
wherein in response to partial compression of both of the central
portions together, the reservoir partially collapses to expel some
of the medicament out of the reservoir; and
wherein the central portions, after partial compression of both
of the central portions together and partial collapse of the reservoir,
expand to reform the reservoir and to draw fluid into the reservoir,
thereby aspirating the needle assembly means.
2. A single-use disposable syringe in accordance with claim 1
in which the needle assembly means includes:
a hypodermic needle pointed at both ends;
hub means fastened to the hypodermic needle for supporting the
hypodermic needle;
a tube for holding the hypodermic needle and the hub means, having
a closed end connected to the injection port and an open end;
means for laterally moving the hypodermic needle within the tube
to pierce the closed end of the tube with one of the pointed ends
of the hypodermic needle; and
means for protecting the hypodermic needle.
3. A single-use disposable syringe in accordance with claim 1
in which the thermoplastic material is comprised of polyethylene
terephthalate.
4. A injection device in accordance with claim 1 in which the
sheets of thermoplastic material include a heat-sealable material
at least on the sides of the thermoplastic sheets that face each
other.
5. A single-use disposable syringe in accordance with claim 4
in which the heat-sealable material is comprised of low density
polyethylene.
6. A single-use disposable syringe in accordance with claim 4
in which the reservoir means includes a material that has low water
vapor transmissivity.
7. A single-use disposable syringe in accordance with claim 6
in which the material that has low water vapor transmissivity is
comprised of polyvinylidene chloride.
8. A single-use disposable syringe in accordance with claim 1
in which the expanded central portions form a reservoir comprising:
a compressible convex first dome;
a compressible convex second dome; and
a connecting member, coupled to the first and second domes, for
spacing apart the first and second domes, to enable the reservoir
to substantially collapse in response to complete compression of
both of the domes together;
wherein in response to complete compression of both of the domes
together, each of the domes becomes concave to prevent the reservoir
from being reformed.
9. A single-use disposable syringe in accordance with claim 8
in which the connecting member forms a cylinder.
10. A single-use disposable syringe for providing a medicament
for injection into a patient, the syringe comprising:
needle assembly means for injecting the medicament into the patient;
reservoir means for storing the medicament and for expelling the
medicament into the needle assembly means, the reservoir means including
a compressible convex first dome formed of a thermoplastic material;
a compressible convex second dome formed of the thermoplastic material;
and
a connecting member, coupled to the first and second domes, for
spacing apart the first and second domes, to enable the reservoir
means to substantially collapse in response to complete compression
of both of the domes together;
wherein in response to complete compression of both of the domes
together, each of the domes becomes concave to prevent the reservoir
means from being reformed; and
injection port means extending from the reservoir means and connected
to the needle assembly means for directing the medicament from the
reservoir means to the needle assembly means;
wherein the reservoir means substantially collapses in response
to complete compression of both of the domes together to prevent
the reservoir means from being reformed and to expel the medicament
out of the reservoir means;
wherein in response to partial compression of both of the domes
together, the reservoir means partially collapses to expel some
of the medicament out of the reservoir means; and
wherein the domes, after partial compression of both of the domes
together and partial collapse of the reservoir means, expand to
reform the reservoir means and to draw fluid into the reservoir
means, thereby aspirating the needle assembly means.
11. A single-use disposable syringe in accordance with claim 10
further comprising filling port means extending from the reservoir
means for filling the reservoir means with the medicament.
12. A single-use disposable syringe in accordance with claim 10
in which the needle assembly means includes:
a hypodermic needle pointed at both ends;
hub means fastened to the hypodermic needle for supporting the
hypodermic needle;
a tube for holding the hypodermic needle and the hub means, having
a closed end connected to the injection port and an open end;
means for laterally moving the hypodermic needle within the tube
to pierce the closed end of the tube with one of the pointed ends
of the hypodermic needle; and
means for protecting the hypodermic needle.
13. A single-use disposable syringe in accordance with claim 10
in which the thermoplastic material is comprised of polyethylene
terephthalate.
14. A injection device in accordance with claim 10 in which the
thermoplastic material includes a heat-sealable material at least
on the sides of the thermoplastic material that face each other.
15. A single-use disposable syringe in accordance with claim 14
in which the heat-sealable material is comprised of low density
polyethylene.
16. A single-use disposable syringe in accordance with claim 14
in which the reservoir means includes a material that has low water
vapor transmissivity.
17. A single-use disposable syringe in accordance with claim 16
in which the material that has low water vapor transmissivity is
comprised of polyvinylidene chloride.
18. A single-use disposable syringe for providing a medicament
for injection into a patient, the syringe comprising:
needle assembly means for injecting the medicament into the patient;
and
reservoir means for storing the medicament and for expelling the
medicament into the needle assembly means, the reservoir means including
two sheets of thermoplastic material, wherein each of the two thermoplastic
sheets is comprised of an expanded central portion, an expanded
injection neck portion, an expanded filling neck portion, and a
substantially flat peripheral portion,
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are opposite and coextensive to
each other and are sealed together face-to-face, and the expanded
central portions are opposite and coextensive to each other, to
form a reservoir for storing the medicament,
in which the expanded injection neck portions extend from the expanded
central portions to a first end of each sheet, and are opposite
and coextensive to each other, to form an injection port extending
from the reservoir and connected to the needle assembly means for
directing the medicament from the reservoir to the needle assembly
means,
in which the expanded filling neck portions extend from the expanded
central portions to a second end of each sheet, and are opposite
and coextensive to each other, to form a filling port extending
from the reservoir for filling the reservoir with the medicament,
and
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are sealed together face-to-face
prior to formation of the expanded central portions of the two sheets,
and the central portions of the two sheets are expanded to form
the reservoir after the peripheral portions are sealed together
by injecting compressed gas between the central portions of the
two sheets until the central portions expand to fill a cavity of
a mold;
wherein the expanded central portions are compressible, and in
response to complete compression of both of the central portions
together, the reservoir substantially collapses to prevent the reservoir
from being reformed and to expel the medicament out of the reservoir;
wherein in response to partial compression of both of the central
portions together, the reservoir partially collapses to expel some
of the medicament out of the reservoir; and
wherein the central portions, after partial compression of both
of the central portions together and partial collapse of the reservoir,
expand to reform the reservoir and to draw fluid into the reservoir,
thereby aspirating the needle assembly means.
19. A single-use disposable syringe in accordance with claim 18
in which the expanded central portions form a reservoir comprising:
a compressible convex first dome;
a compressible convex second dome; and
a connecting member, coupled to the first and second domes, for
spacing apart the first and second domes, to enable the reservoir
to substantially collapse in response to complete compression of
both of the domes together;
wherein in response to complete compression of both of the domes
together, each of the domes becomes concave to prevent the reservoir
from being reformed.
20. A single-use disposable syringe for providing a medicament
for injection into a patient, the syringe comprising:
needle assembly means for injecting the medicament into the patient;
and
reservoir means for storing the medicament and for expelling the
medicament into the needle assembly means, the reservoir means including
two sheets of thermoplastic material, wherein each of the two thermoplastic
sheets is comprised of an expanded central portion, an expanded
injection neck portion, an expanded filling neck portion, and a
substantially flat peripheral portion,
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are opposite and coextensive to
each other and are sealed together face-to-face, and the expanded
central portions are opposite and coextensive to each other, to
form a reservoir for storing the medicament,
in which the expanded injection neck portions extend from the expanded
central portions to a first end of each sheet, and are opposite
and coextensive to each other, to form an injection port extending
from the reservoir and connected to the needle assembly means for
directing the medicament from the reservoir to the needle assembly
means,
in which the expanded filling neck portions extend from the expanded
central portions to a second end of each sheet, and are opposite
and coextensive to each other, to form a filling port extending
from the reservoir for filling the reservoir with the medicament,
and
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are sealed together face-to-face
prior to formation of the expanded central portions of the two sheets,
and the central portions of the two sheets are expanded to form
the reservoir after the peripheral portions are sealed together
by drawing apart the central portions of the two sheets using a
vacuum until the central portions expand to fill a cavity of a mold;
wherein the expanded central portions are compressible, and in
response to complete compression of both of the central portions
together, the reservoir substantially collapses to prevent the reservoir
from being reformed and to expel the medicament out of the reservoir;
wherein in response to partial compression of both of the central
portions together, the reservoir partially collapses to expel some
of the medicament out of the reservoir; and
wherein the central portions, after partial compression of both
of the central portions together and partial collapse of the reservoir,
expand to reform the reservoir and to draw fluid into the reservoir,
thereby aspirating the needle assembly means.
21. A single-use disposable syringe in accordance with claim 20
in which the expanded central portions form a reservoir comprising:
a compressible convex first dome;
a compressible convex second dome; and
a connecting member, coupled to the first and second domes, for
spacing apart the first and second domes, to enable the reservoir
to substantially collapse in response to complete compression of
both of the domes together;
wherein in response to complete compression of both of the domes
together, each of the domes becomes concave to prevent the reservoir
from being reformed.
22. A single-use disposable syringe for providing an injection
into a patient, the syringe comprising:
a medicament;
needle assembly means for injecting the medicament into the patient;
and
reservoir means for storing the medicament and for expelling the
medicament into the needle assembly means, the reservoir means including
two sheets of thermoplastic material, wherein each of the two thermoplastic
sheets is comprised of an expanded central portion, an expanded
injection neck portion, and a substantially flat peripheral portion,
in which the substantially flat peripheral portions of the two
sheets of thermoplastic material are opposite and coextensive to
each other and are sealed together face-to-face, and the expanded
central portions are opposite and coextensive to each other, to
form a reservoir for storing the medicament, and
in which the expanded injection neck portions extend from the expanded
central portions to a first end of each sheet, and are opposite
and coextensive to each other, to form an injection port extending
from the reservoir and connected to the needle assembly means for
directing the medicament from the reservoir to the needle assembly
means;
wherein the expanded central portions are compressible, and in
response to complete compression of both of the central portions
together, the reservoir substantially collapses to prevent the reservoir
from being reformed and to expel the medicament out of the reservoir;
wherein in response to partial compression of both of the central
portions together, the reservoir partially collapses to expel some
of the medicament out of the reservoir; and
wherein the central portions, after partial compression of both
of the central portions together and partial collapse of the reservoir,
expand to reform the reservoir and to draw fluid into the reservoir,
thereby aspirating the needle assembly means.
23. A single-use disposable syringe in accordance with claim 22
in which the needle assembly means includes:
a hypodermic needle pointed at both ends;
hub means fastened to the hypodermic needle for supporting the
hypodermic needle;
a tube for holding the hypodermic needle and the hub means, having
a closed end connected to the injection port and an open end;
means for laterally moving the hypodermic needle within the tube
to pierce the closed end of the tube with one of the pointed ends
of the hypodermic needle; and
means for protecting the hypodermic needle.
24. A single-use disposable syringe in accordance with claim 22
in which the expanded central portions form a reservoir comprising:
a compressible convex first dome;
a compressible convex second dome; and
a connecting member, coupled to the first and second domes, for
spacing apart the first and second domes, to enable the reservoir
to substantially collapse in response to complete compression of
both of the domes together;
wherein in response to complete compression of both of the domes
together, each of the domes becomes concave to prevent the reservoir
from being reformed.
Description FIELD OF THE INVENTION
This invention relates to the structure and manufacture of syringes,
and more particularly to syringes that cannot be reused.
BACKGROUND OF THE INVENTION
The rapid spread of acquired immune deficiency syndrome (AIDS)
among intravenous drug users has created an urgent need for syringes
that cannot be reused. In many situations, injections are given
to patients without carefully controlling access to syringes. The
use of reusable syringes under those circumstances increases the
risk of infection. An infection can occur whenever syringes that
have been used previously, and which therefore are no longer sterile,
are used to administer injections.
Of course, reusable syringes are suitable for administration of
a vaccine or other injectable medicaments when the injections are
performed by a professional staff in formal health care facilities.
In a hospital environment, skilled personnel sterilize the syringe
for reuse, refill the syringe with the appropriate medicament, and
personally administer the injections. Furthermore, circulation of
these syringes is managed and controlled.
However, there are times when it is necessary or more economical
to administer injections outside a hospital environment. For example,
it may be necessary to give injections to a large number of individuals
over a short period of time, patients may be located in a developing
country or in an area without convenient access to a hospital or
medical personnel, or it may be desirable to permit injections to
be administered to a patient at his or her home or while he or she
travels. Under these circumstances, it is virtually impossible to
prevent misuse of the syringes. Furthermore, it is much more difficult
to ensure proper sterilization of the syringes, particularly if
medicaments are administered by non-professional personnel.
It is also important to develop an easy method of manufacturing
a syringe that cannot be reused. Even though the use of disposable
syringes reduces the risk of infection, it is not economically feasible
to replace reusable syringes with disposable syringes unless the
disposable syringes are made in a relatively inexpensive manner.
Unfortunately, single use syringes that have been developed often
are expensive to manufacture, or are so bulky that the syringes
are inconvenient to ship and store.
In order to ensure proper administration of an injection, it is
important that the syringe be designed to allow aspiration to verify
proper placement of the needle in the patient. Trained medical personnel
confirm whether a needle is or is not in a blood vessel by aspirating
prior to injection of a medicament. In aspiration, a negative or
suction pressure causes the needle to draw material into the syringe
from the patient. The person administering the injection then visually
examines the syringe to see if any blood has been drawn into the
syringe through the needle. If, for example, the injection should
be administered intravenously, the presence of blood after aspiration
indicates proper placement of the needle.
The goals of designing a syringe that can be aspirated and which
cannot be reused appear to be in conflict. Disposable syringes that
contain a prefilled vaccine delivery system typically have a squeezable
body portion or other elastic receptacle. In these syringes, a positive
pressure is applied on or by the receptacle to force the medicament
out through the needle. In order to perform aspiration, however,
a negative pressure is applied to the receptacle. Unfortunately,
the negative pressure needed to aspirate the syringe also may be
used to reform the elastic receptacle, allowing the syringe to be
reused.
Therefore, there is a need for an inexpensive and easy to manufacture
syringe that cannot be reused, but which can be used to perform
aspiration.
SUMMARY OF THE INVENTION
It is an object of the present invention to avoid some of the problems
and disadvantages associated with prior art syringes.
It is therefore desirable to provide an injection device which
cannot be reused.
There is great concern among public health officials about reducing
the possibility of transmission of blood borne diseases by the use
or reuse of an improperly sterilized or unsterilized needle and
syringe. In some U.S. cities the spread of AIDS is growing most
rapidly due to the sharing of needles and syringes by intravenous
drug abusers. In addition, many third world countries reuse disposable
syringes, with the potential of spreading blood borne diseases.
An invention that renders a disposable syringe nonreusable may have
an important impact on reducing any potential risks. There is the
potential for rapid application and use of such an invention in
containing the national and international spread of AIDS and other
blood borne diseases.
It also would be beneficial to provide a disposable injection device
which is easily used in the field by non-professional but trained
personnel. Preferably, the injection device would be rendered incapable
of reuse by providing a reservoir that collapses when emptied of
contents during administration of an injection. Additionally, the
reservoir for the injection device should have sufficient elasticity
and integrity to permit aspiration during the early stages of administration
of the injection.
Finally, it would be advantageous to provide an injection device
that can be economically manufactured using a fabrication process
which incorporates steps that create a reservoir that is sealed
properly but which is structured to collapse when the reservoir
is emptied a single time.
To achieve the objects and in accordance with the purpose of the
invention, as embodied and broadly described herein, the single-use
disposable syringe of this invention includes needle assembly means
for injecting the medicament into the patient. The syringe also
is provided with reservoir means for storing the medicament and
for expelling the medicament into the needle assembly means. The
reservoir means includes two sheets of thermoplastic material, wherein
each of the two thermoplastic sheets is comprised of an expanded
central portion, an expanded injection neck portion, an expanded
filling neck portion, and a substantially flat peripheral portion.
The substantially flat peripheral portions of the two sheets of
thermoplastic material are opposite and coextensive to each other
and are sealed together face-to-face, and the expanded central portions
are opposite and coextensive to each other, to form a reservoir
for storing the medicament. The expanded injection neck portions
extend from the expanded central portions to a first end of each
sheet, and are opposite and coextensive to each other, to form an
injection port extending from the reservoir and connected to the
needle assembly means for directing the medicament from the reservoir
to the needle assembly means. The expanded filling neck portions
extend from the expanded central portions to a second end of each
sheet, and are opposite and coextensive to each other, to form a
filling port extending from the reservoir for filling the reservoir
with the medicament. The expanded central portions are compressible,
and in response to complete compression of both of the central portions
together, the reservoir substantially collapses to prevent the reservoir
from being reformed and to expel the medicament out of the reservoir.
In response to partial compression of both of the central portions
together, the reservoir partially collapses to expel some of the
medicament out of the reservoir. The central portions, after partial
compression of both of the central portions together and partial
collapse of the reservoir, expand to reform the reservoir and to
draw fluid into the reservoir, thereby aspirating the needle assembly
means.
In one embodiment of the single-use disposable syringe of the invention,
the substantially flat peripheral portions of the two sheets of
thermoplastic material are sealed together face-to-face prior to
formation of the expanded portions of the two sheets. The central
portions of the two sheets, and the injection neck portions and
filling neck portions extending therefrom, are expanded to form
the reservoir, injection port, and filling port after the peripheral
portions are sealed together, by injecting compressed gas between
the appropriate portions of the two sheets or by drawing apart the
appropriate portions of the two sheets using a vacuum, until those
portions expand to fill a cavity of a mold.
In another embodiment of the single-use disposable syringe, the
expanded central portions form a reservoir that comprises a compressible
convex first dome, a compressible convex second dome, and a connecting
member. The connecting member, which is coupled to the first and
second domes, is provided for spacing apart the first and second
domes, and for enabling the reservoir to substantially collapse
in response to complete compression of both of the domes together.
In response to complete compression of both of the domes together,
each of the domes becomes concave to prevent the reservoir from
being reformed.
Additional objects and advantages of the invention will be set
forth in part in the description which follows, and in part will
be obvious from the description, or may be learned by practice of
the invention. The objects and advantages of the invention may be
realized and attained by means of the instrumentalities and combinations
particularly pointed out in the appended claims.
The accompanying drawings, which are incorporated in and constitute
a part of this specification, illustrate an embodiment of the invention,
and together with the description, serve to explain the principles
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is diagram of embodiment of the present invention showing
a needle assembly means in greater detail.
FIG. 2 is a diagram of an embodiment of the present invention after
piercing of a membrane with a needle.
FIG. 3 is a diagram of an embodiment of the present invention.
FIG. 4 is a diagram of a top view of an embodiment of the present
invention.
FIG. 5 is a diagram of a side view of an embodiment of the present
invention prior to use.
FIG. 6 is a diagram of a side view of an embodiment of the present
invention rendered incapable of reuse.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the present preferred embodiments
of the invention, examples of which are illustrated in the accompanying
drawings.
An embodiment of a single-use disposable syringe for providing
a medicament for injection into a patient is shown in FIG. 1 and
is represented graphically by the numeral 10.
In accordance with the invention, the syringe includes needle assembly
means for injecting the medicament into the patient. The needle
assembly means includes a hypodermic needle. As embodied in syringe
10 shown in FIG. 1 a hypodermic needle 12 is provided that is pointed
at both ends 14 and 16.
The needle assembly means contains hub means fastened to the hypodermic
needle for supporting the hypodermic needle, and a tube for holding
the hypodermic needle and the hub means, having a closed end connected
to an injection port and an open end. Preferably, the tube is provided
by a nozzle 18 the hub means is provided by a needle hub 20 and
the closed end of the tube is formed by a nozzle membrane 22.
As illustrated in FIGS. 1 and 2 hypodermic needle 12 passes through
needle hub 20. The needle hub is made of polystyrene and is secured
to hypodermic needle 12 using epoxy resin as an adhesive. In this
embodiment, nozzle 18 and needle hub 20 are cylindrical in shape.
Preferably, needle hub 20 is comprised of a first section 24 of
large diameter and a second section 26 of small diameter. The dimensions
of large diameter first section 24 and of the internal diameter
of nozzle 18 are selected so that needle hub 20 is frictionally
held within nozzle 18 but can be moved laterally within nozzle
18 when a force is applied to needle hub 20. One of the sharp pointed
ends 14 of hypodermic needle 12 penetrates nozzle membrane 22 when
needle hub 20 is moved toward the nozzle membrane. The other sharp
pointed end 16 of hypodermic needle 12 is used to pierce the skin
of the patient so that the medicament can be administered intravenously
or intramuscularly.
As embodied herein, nozzle 18 also is provided with an internal
rib 28 between nozzle membrane 22 and needle hub 20 to prevent pointed
end 14 of the hypodermic needle from piercing the closed end of
the tube unless a sufficient force is applied. The dimensions of
large diameter first section 24 and of internal rib 28 are selected
so that needle hub 20 will not move past rib 28 unless a relatively
larger force is applied to needle hub 20. This structure reduces
the risk of unintentional piercing of nozzle membrane 22 at times
when no one is ready to administer an injection.
Means are provided for protecting the hypodermic needle. As shown
in FIG. 1 syringe 10 has a protector cap 30. Protector cap 30 is
a cylinder having a closed end 32 and an open end 34. Protector
cap 30 is long enough, together with nozzle 18 to enclose hypodermic
needle 12 without permitting the closed end of the protector cap
to come into contact with sharp pointed end 16 of the hypodermic
needle. The open end of the protector cap fits inside the nozzle,
and preferably the external diameter of the open end is selected
so that the protector cap is snugly held in position within nozzle
18. As a result, the hypodermic needle is kept sterile and is not
exposed during storage and shipment of the syringe. Following the
piercing of nozzle membrane 22 protector cap 30 is removed in order
to administer an injection. After the syringe has been used to inject
a medicament into a patient, the protector cap can be reinserted
into nozzle 18 and used as a protective cover over the hypodermic
needle to prevent accidental stabbing by sharp pointed end 16. As
embodied herein, the protector cap is made of polyethylene.
The means for laterally moving the hypodermic needle within the
tube to pierce the closed end of the tube with one of the pointed
ends of the hypodermic needle is provided by cooperation of protector
cap 30 with needle hub 20. The internal diameter of open end 34
of the protector cap is selected so that the small diameter second
section 26 of needle hub 20 fits snugly within the open end of the
protector cap. The external diameter of open end 34 of the protector
cap is selected so that the protector cap can be moved laterally
within nozzle 18. This design permits lateral movement of hypodermic
needle 12 without angular displacement of the needle as it moves
toward and through nozzle membrane 22 at the closed end of nozzle
18.
As shown in FIG. 2 protector cap 30 can be used as a tool, in
which open end 34 of the protector cap is pushed against the large
diameter first section 24 of needle hub 20. In this way, a sufficient
force can be safely applied to needle hub 20 to force it past internal
rib 28. Protector cap 30 then continues pushing large diameter first
section 24 of needle hub 20 until sharp pointed end 14 of hypodermic
needle 12 penetrates nozzle membrane 22. The protector cap is long
enough to allow needle hub 20 and hypodermic needle 12 to be laterally
moved far enough within nozzle 18 to pierce nozzle membrane 22 with
sharp pointed end 14 of the hypodermic needle.
As embodied herein, protector cap 30 also may be provided with
an external rim 36. External rim 36 allows a person handling the
syringe to more easily control the lateral movement of needle hub
20 within the nozzle by applying a force to the external rim.
In accordance with the invention, the syringe includes reservoir
means for storing the medicament and for expelling the medicament
into the needle assembly means. The reservoir means includes two
sheets of thermoplastic material. Each of the two thermoplastic
sheets has an expanded central portion, an expanded injection neck
portion, and a substantially flat peripheral portion.
As embodied in FIG. 2 the reservoir means is formed from a pair
of sheets 38a and 38b of thermoplastic material. As shown in FIG.
3 each sheet 38 has a central portion 40 an injection neck portion
42 and a peripheral portion 44. Peripheral portion 44 is substantially
flat, and injection neck portion 42 is expanded. Prior to administration
of an injection to a patient, central portion 40 is expanded.
In accordance with the invention, the substantially flat peripheral
portions of the two sheets of thermoplastic material are opposite
and coextensive to each other and are sealed together face-to-face.
The expanded central portions are opposite and coextensive to each
other. The central and peripheral portions of the two sheets form
a reservoir for storing the medicament.
A reservoir 46 is shown in FIGS. 2 and 5 prior to compression of
central portions 40 of the pair of sheets 38 together. Reservoir
46 has sufficient volume to store an appropriate dose of the medicament
being administered. As embodied herein, the shape of reservoir 46
is defined by the sealing together of the pair of sheets 38 at the
peripheral portions and the separation of the two sheets at the
central portions.
In the present invention, the expanded injection neck portions
extend from the expanded central portions to a first end of each
sheet, and are opposite and coextensive to each other. The expanded
injection neck portions form an injection port extending from the
reservoir and connected to the needle assembly means for directing
the medicament from the reservoir to the needle assembly means.
In a preferred embodiment of the invention, injection port 48 is
provided. As shown in FIGS. 2 5 and 6 injection port 48 extends
from reservoir 46 to the needle assembly means. The parts of expanded
injection neck portions 42 of the two sheets which overlap nozzle
18 are sealed to the nozzle, as shown in FIGS. 3 and 4. Preferably,
the injection port is connected to the needle assembly means by
heat sealing, although an adhesive may be used if desired. The separation
of the pair of sheets 38 at injection neck portions 42 provides
a channel between the reservoir and the nozzle.
Needle hub 20 is positioned on needle 12 so that pointed end 14
is shorter than pointed end 16. The hypodermic needle and needle
hub 20 are placed in nozzle 18 with shorter end 14 pointing at nozzle
membrane 22. As shown in FIG. 2 large diameter first section 24
of needle hub 20 is pushed by open end 34 of protector cap 30 until
the first section of the needle hub contacts nozzle membrane 22
which prevents end 14 of hypodermic needle 12 from being moved too
far past the pierced nozzle membrane. In this position, nozzle membrane
22 is sufficiently thick relative to pointed end 14 of the hypodermic
needle so that pointed end 14 pierces the nozzle membrane and just
barely extends beyond the nozzle membrane toward reservoir 46.
Alternately, the side of nozzle membrane 22 facing reservoir 46
may be provided with an aperture (not shown) slightly larger in
diameter than hypodermic needle 12 and extending partially through
the nozzle membrane. In this alternate embodiment, after pushing
needle hub 20 against the nozzle membrane, pointed end 14 extends
into, but not significantly beyond, the aperture and penetrates
the remainder of the nozzle membrane.
After needle hub 20 is laterally moved far enough within nozzle
18 to pierce nozzle membrane 22 the medicament stored in reservoir
46 can flow into the hypodermic needle and be injected into a patient.
Since pointed end 14 of the hypodermic needle does not extend significantly
beyond nozzle membrane 22 almost all of the medicament stored in
reservoir 46 can be expelled into the hypodermic needle.
Two important features are provided in the syringe of the present
invention. First, syringe 10 is not reusable after a single injection
is administered to a patient. Second, in order to determine whether
hypodermic needle 12 has been properly placed, it is possible to
aspirate the needle, i.e., to draw material from a patient into
syringe 10 prior to administering an injection to the patient. These
functions are performed using reservoir 46.
It is important to recognize tha one of these functions, aspiration,
is carried out when a reservoir is mostly full. In contrast, the
other function, rendering a syringe unusable, is executed only after
the reservoir has been emptied. Therefore, in accordance with the
invention, reservoir 46 is designed to reform after partial compression
in order to draw fluid into the reservoir, and to substantially
collapse after complete compression to prevent the reservoir from
being reformed.
In the present invention, the expanded central portions of the
pair of sheets are compressible. Furthermore, in response to complete
compression of both of the central portions together, the reservoir
substantially collapses to prevent the reservoir from being reformed
and to expel the medicament out of the reservoir. In the preferred
embodiment shown in FIGS. 5 and 6 personnel administering an injection
compress both central portions 40 of syringe 10 together. As a result,
almost all of the medicament is forced out of reservoir 46 and into
hypodermic needle 12 via injection port 48. After reservoir 46 collapses
due to complete compression of the central portions together, as
shown in FIG. 6 the reservoir cannot be reformed, preventing reuse
of syringe 10.
In accordance with the invention, in response to partial compression
of both of the central portions together, the reservoir partially
collapses to expel some of the medicament out of the reservoir.
Furthermore, the central portions, after partial compression of
both of the central portions together and partial collapse of the
reservoir, expand to reform the reservoir and to draw fluid into
the reservoir, thereby aspirating the needle assembly means.
In a preferred embodiment of the invention, the syringe may be
provided with reservoir means including a compressible convex first
dome formed of a thermoplastic material and a compressible convex
second dome formed of the thermoplastic material. As embodied in
FIGS. 2 and 5 reservoir 46 is formed by a convex first dome 50
and a convex second dome 52. Preferably, each dome provides one
hemisphere for the reservoir. The convex shape of domes 50 and 52
prior to compression permits storage of a medicament within reservoir
46.
Preferably, the reservoir means also includes a connecting member,
coupled to the first and second domes, for spacing apart the first
and second domes, to enable the reservoir means to substantially
collapse in response to complete compression of both of the domes
together. In response to complete compression of both of the domes
together, each of the domes becomes concave and the reservoir means
substantially collapses to prevent the reservoir means from being
reformed.
In the preferred embodiment shown in FIGS. 2 and 5 a connecting
member 54 is provided. In this embodiment, connecting member 54
is cylindrical in shape, is connected to the bottom of each of the
hemispheres formed by the two domes, and spaces apart domes 50 and
52. As shown in FIG. 6 because of the presence of connecting member
54 personnel administering an injection must force both of the
domes to assume a concave shape in order to completely compress
domes 50 and 52 together. Once the domes are forced to assume a
concave shape, reservoir 46 cannot be reformed and syringe 10 cannot
be reused.
In accordance with this embodiment of the invention, in response
to partial compression of both of the domes together, the reservoir
means partially collapses. After partial compression of both of
the domes together and partial collapse of the reservoir means,
the domes expand to reform the reservoir means and to draw fluid
into the reservoir, thereby aspirating the needle assembly means.
Unless connecting member 54 is placed between domes 50 and 52
the administration of an injection may not render the syringe unusable.
Without the connecting member, the central portions of each sheet
38 are not forced past the bottom of the dome formed by that sheet.
As a result, after complete compression of the domes together, it
is possible for the central portions of each sheet to expand and
for domes 50 and 52 to reassume a convex shape.
If a connecting member or its equivalent is not provided between
the two domes that form a reservoir, a syringe has to be structured
differently in order to prevent its reuse. For example, a reservoir
may be designed so that one of the two domes is compressible, while
the other dome is stationary. In such a structure, the reservoir
collapses when the compressible dome is deformed into the stationary
dome. However, in such a device, the two domes would be fabricated
using different materials, or additional mechanical structure would
be needed to prevent compression of the stationary dome. Therefore,
in this example of an alternate structure, the resulting syringe
is more expensive and more difficult to manufacture.
In the syringe of the present invention, a filling port means may
be provided that extends from the reservoir means for filling the
reservoir means with the medicament. Preferably, each of two thermoplastic
sheets has an expanded filling neck portion, wherein the expanded
filling neck portions extend from the expanded central portions
to a second end of each sheet, and are opposite and coextensive
to each other, to form a filling port extending from the reservoir.
In the preferred embodiment of the invention shown in FIG. 1 each
sheet 38 has a filling neck portion 56 extending from central portion
40 to an end of the sheet. The filling neck portions are opposite
and coextensive to each other, and are expanded prior to filling
of reservoir 46 with a medicament. The separation of the pair of
sheets 38 at filling neck portions 56 and the sealing together of
the pair of sheets at surrounding peripheral portions 44 provides
a channel into the reservoir from outside syringe 10. This channel
constitutes a filling port 58 that is provided at the opposite end
of syringe 10 from injection port 48. After the filling port is
used to fill reservoir 46 with a medicament, filling neck portions
56 are sealed together so that the medicament can be stored.
In manufacturing syringe 10 any sheet may be used that is thermoplastic,
is heat-sealable on at least one surface, and has the vapor impermeability
required for the medicament being packaged. As embodied herein,
these properties are achieved by coating a film of thermoplastic
material with a material that has low water vapor transmissivity,
and laminating together the film of thermoplastic material with
a heat-sealable film. Preferably, polyethylene terepthalate is used
as the thermoplastic substrate, the requisite vapor impermeability
is provided by a coating of polyvinylidene chloride, and a low density
polyethylene film is used to provide heat-sealable surfaces.
In the preferred embodiment of the invention, the thermoplastic
material used to form the two sheets included in the reservoir means
is made of a material that provides formability, rigidity, and strength.
It also is desirable to use a material that can be radiation sterilized.
Finally, there is a requirement that the materials used to manufacture
the syringe be transparent so that the syringe can be inspected
for the presence of particulate matter. Preferably, a film of polyethylene
terephthalate that is about 120 microns thick is used as the thermoplastic
material. This material is also referred to as PETG and is commercially
available under the trademark KODAR.
In the preferred embodiment of the invention, the reservoir means
includes a heat-sealable material, such as low density polyethylene.
Preferably, the thermoplastic material and the heat-sealable material
are laminated together using polyurethane as an adhesive, and the
heat-sealable material is transparent. As a result, each sheet 3
is made up of at least two films of different materials.
In a preferred embodiment of the reservoir means, a material that
has low water vapor transmissivity is included. These properties
are designed to prevent water from passing through the material
used to form reservoir 46. If a syringe is provided which allows
water to escape from the reservoir, this may result in an unsafe
dosage of the medicament that remains in the reservoir. Polyvinylidene
chloride is a suitable material and is transparent. This material
is also referred to as PVDC and is commercially available under
the trademark SARAN. The material with low water vapor transmissivity
is emulsion coated on a substrate of the thermoplastic material.
In summary, the process of manufacturing each sheet 38 begins with
a polyethylene terephthalate film. An emulsion of polyvinylidene
chloride is then coated on the film and dried. Finally, a low density
polyethylene film is glued to the polyethylene terephthalate film
using polyurethane.
The preferred method of manufacturing syringe 10 will now be described.
To start the process, two separate rolls of material having thermoplastic
and heat-sealable properties are provided to form the pair of sheets
38. The rolls contain enough material to mass produce a number of
syringes 10.
The two rolls of material are unrolled together face-to-face. The
material is unrolled so that the films of heat-sealable material
on at least one surface of each sheet 38 are in contact with each
other.
During the next step in the process, peripheral portion 44 in one
sheet 38 is heat sealed to coextensive peripheral portion 44 in
the other sheet, making use of the properties of the heat-sealable
material in the films that are in contact with each other. As a
result, the substantially flat peripheral portions of the two sheets
are formed and are sealed together face-to-face. In another embodiment,
an adhesive can be used to seal together the two sheets.
In accordance with the preferred embodiment of the invention, the
substantially flat peripheral portions of the two sheets of thermoplastic
material are sealed together face-to-face prior to formation of
the expanded portions of the two sheets. The central portions, injection
neck portions, and filling neck portions of the two sheets are expanded
to form the reservoir, injection port, and filling port after the
peripheral portions are sealed together by injecting compressed
gas between the unsealed portions of the two sheets until these
portions expand to fill the cavities of a mold. Alternately, these
portions of the two sheets are expanded to form the reservoir, injection
port, and filling port after the peripheral portions are sealed
together by drawing apart the unsealed portions of the two sheets
using a vacuum until these unsealed portions expand to fill the
cavities of the mold.
Preferably, a mold (die) is provided so that the reservoir and
port means may be formed. In the mold (not shown), cavities are
provided to define the desired shape of reservoir 46 injection
port 48 and filling port 58.
To manufacture the preferred embodiment of syringe 10 the mold
has a pair of cavities, each of which is dome-shaped at the bottom
and cylindrical at the top. The pair of cavities of the mold and
central portions 40 of the two sheets are coextensive with each
other. As a result, a syringe with two convex domes 50 and 52 and
connecting member 54 can be fabricated. The mold is heated so that
the thermoplastic material included in the pair of sheets 38 is
softened and can be thermoformed. Compressed air is then injected
(blown) between the central portions 40 of the two sheets to separate
and expand the central portions. The compressed air forces the central
portions to fill the cavities in the mold and assume the appropriate
shape of the reservoir. Alternately, reservoir 46 can be formed
using a vacuum to draw apart central portions 40. Alternately, it
also may be possible to fabricate the reservoir using a mechanical
plug (not shown).
The remaining portions of each sheet 38 i.e., injection neck portions
42 and filling neck portions 56 also may be thermoformed at the
same time using compressed gas or a vacuum to expand those portions
of the sheets. Separate cavities coextensive with the injection
neck portions and the filling neck portions of the pair of sheets
38 must be provided in the mold to define the shape of the injection
port and the filling port of syringe 10. In this way, injection
port 48 filling port 58 and reservoir 46 can be formed together.
When syringe 10 is fabricated by using compressed gas or a vacuum
to form reservoir 46 after heat sealing of the peripheral portions
surrounding the reservoir, important advantages are obtained. In
syringe 10 an excellent seal is first provided, and then the reservoir
is blown or drawn open. As a result, the integrity of reservoir
46 is secured using a convenient and economical process, and rupture
of syringe 10 at the sealing areas is less likely.
In other devices, a reservoir formed of two or more sheets is generally
formed by sealing together the parts of the reservoir after these
parts have assumed their desired shapes. In these devices, failures
of the seal due to delamination of the sheets or other reasons are
more likely. Furthermore, manufacture of such devices may be more
difficult and expensive because the tolerances are made tighter
during heat sealing to ensure the integrity of the seals between
the parts of the reservoir.
After the reservoir for syringe 10 is formed, the next step in
the process is coupling of the needle assembly means to the injection
port. Preferably, nozzle 18 is used to provide the needle assembly
means with a tube for holding hypodermic needle 12 and needle hub
20 and the nozzle and the injection port are cylindrical in shape.
The diameters of nozzle 18 and injection port 48 are selected so
that the nozzle can be inserted within the injection port.
Next, the needle assembly means is heat sealed to the injection
port. In the preferred embodiment of syringe 10 nozzle 18 also
is formed of a heat sealable material, such as low density polyethylene.
Since nozzle 18 is inserted within injection port 48 the films
of heat-sealable material on at least one surface of each sheet
38 will be in contact with nozzle 18.
These steps are repeated using the rest of the material in the
two rolls to mass produce a number of syringes 10 at relatively
low cost. As a result, reels of about 1000 syringes are obtained,
which can then be sterilized. Preferably, radiation is used as the
most cost effective way to sterilize the syringes.
After these steps are performed, the only remaining step is filling
of reservoir 46 with an appropriate medicament. This step is usually
performed separately from the other steps in the process. Reservoir
46 is filled with the medicament using filling port 58. During the
filling operation, which is performed in a sterile environment,
most of the air in the reservoir is vented and displaced by the
medicament. Following the filling step, filling neck portions 56
of the two sheets 38 are heat sealed together.
When syringe 10 is used to administer an injection, it is important
to point the syringe downward so that reservoir 46 is on top and
hypodermic needle 12 is on bottom. In this way, personnel using
the syringe can prevent any air left in reservoir 46 from being
injected into a patient.
There are a number of vaccines and medicines that are administered
using a syringe. Syringe 10 can be used to deliver for intravenous
or intramuscular injection such medicaments as hepatitis B vaccine,
tetanus toxoid vaccine, heparin, atropine sulfate, morphine sulfate,
ranitidine, lidocaine, meperidine, naloxone, furosemide, and dexamethasone
sodium phosphate.
Syringe 10 also is capable of use with a lyophilized material requiring
reconstitution of the medicament by adding a diluent to the material.
In the case of such a lyophilized material, the reservoir means
may be structured to contain two adjacent compartments separated
by a seal. A drug or vaccine can be reconstituted by rupturing the
seal between a first compartment containing water and a second compartment
containing the lyophilized material. Alternately, a port can be
provided so that sterile water can be added to the reservoir at
the appropriate time. In such an embodiment, it is not necessary
to include a material with low water vapor transmissivity in the
reservoir.
It will be apparent to those skilled in the art that various modifications
and variations can be made in the structure or method of manufacture
of the syringe of the present invention without departing from the
scope or spirit of the invention. For example, the needle assembly
means can be structured in a variety of ways. Thus, it is intended
that the present invention cover modifications and variations of
this invention, provided they come within the scope of the appended
claims and their equivalents. |