U.S. patent application number 14/021888 was filed with the patent office on 2014-01-09 for injection system with hidden needles.
This patent application is currently assigned to Avant Medical Corp.. The applicant listed for this patent is Avant Medical Corp.. Invention is credited to Andrew C. Barnes, Corey M. Magers, John B. Slate.
Application Number | 20140012207 14/021888 |
Document ID | / |
Family ID | 39051770 |
Filed Date | 2014-01-09 |
United States Patent
Application |
20140012207 |
Kind Code |
A1 |
Slate; John B. ; et
al. |
January 9, 2014 |
Injection System with Hidden Needles
Abstract
An auto-injector confines all functional components inside an
enclosed housing, to keep its needle out-of-sight, at all times.
Within the housing, a needle holder positions a needle at a
location. A drive mechanism then simultaneously engages the needle
with a fluid source and accelerates it with a predetermined
momentum for insertion into a patient. After fluid delivery, the
withdrawn needle is moved to storage within the housing for
subsequent disposal.
Inventors: |
Slate; John B.; (Encinitas,
CA) ; Barnes; Andrew C.; (San Diego, CA) ;
Magers; Corey M.; (Encinitas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Avant Medical Corp. |
Thousand Oaks |
CA |
US |
|
|
Assignee: |
Avant Medical Corp.
Thousand Oaks
CA
|
Family ID: |
39051770 |
Appl. No.: |
14/021888 |
Filed: |
September 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12580935 |
Oct 16, 2009 |
8529540 |
|
|
14021888 |
|
|
|
|
11463529 |
Aug 9, 2006 |
7618396 |
|
|
12580935 |
|
|
|
|
Current U.S.
Class: |
604/201 |
Current CPC
Class: |
A61M 5/32 20130101; A61M
5/3287 20130101; A61M 5/34 20130101; A61M 5/326 20130101; A61M
5/425 20130101; A61M 5/46 20130101; A61M 5/008 20130101; A61M
2005/004 20130101; A61M 5/204 20130101 |
Class at
Publication: |
604/201 |
International
Class: |
A61M 5/34 20060101
A61M005/34 |
Claims
1. A housing with a system mounted thereon for injecting a fluid
medicament into a patient, said system comprising: an elongated
hypodermic needle defining an axis and having a sharp proximal end
and a sharp distal end; a fluid reservoir mounted on the housing; a
fluid transfer section formed with a fluid chamber and positioned
for movement along a pathway inside the housing, said fluid chamber
having an input port and an output port, wherein a septum covers
the output port; a flexible hose interconnecting the input port of
the transfer section with the fluid reservoir to establish fluid
communication between the fluid reservoir and the needle; a collar
mounted on the hypodermic needle between the proximal end and the
distal end thereof with the collar extending radially outward from
the needle, wherein the collar limits travel of the needle along
the pathway inside the housing between a first position wherein the
proximal end of the needle is at a distance from the fluid transfer
section and a second position wherein the sharp proximal end of the
needle is engaged in fluid communication with the fluid reservoir
and the sharp distal end of the needle is inserted into the patient
for infusion of the fluid medicament from the reservoir to the
patient while said fluid reservoir remains stationary relative to
movement of the fluid transfer section wherein the needle and the
collar, in combination, establish a needle unit, and wherein the
system incorporates a plurality of needle units and the system
further comprises a holder mounted on the housing to sequentially
present each needle unit for individual travel along the pathway
and to subsequently remove the needle unit from the pathway; an
abutment formed on the housing for contact with the collar to limit
axial movement of the needle in a distal direction relative to the
housing during insertion of the distal end of the needle into the
patient; a recoil mechanism mounted on the abutment for engagement
with the collar to bias the needle in a proximal direction relative
to the housing for subsequent withdrawal of the needle from the
patient when the needle is in its second position; and a means for
driving the fluid transfer section into contact with the needle at
the first position to pierce the septum with the needle and to
position the sharp proximal end of the needle in the chamber of the
fluid transfer section when the collar abuts against the fluid
transfer section to establish fluid communication between the
needle and the fluid source, and for moving the needle from the
first position to the second position.
Description
[0001] This application is a continuation of application Ser. No.
12/580,935, filed Oct. 16, 2009, which is currently pending.
Application Ser. No. 12/580,935 is a continuation of application
Ser. No. 11/463,529, filed Aug. 9, 2006, which issued as Pat. No.
7,618,396 on Nov. 17, 2009. The contents of application Ser. No.
12/580,935 and Pat. No. 7,618,396 are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention pertains generally to systems and
devices for using a needle to inject fluid medicaments into the
body of a patient. More particularly, the present invention
pertains to auto-injectors that can be used by a caregiver, or used
individually by a patient to self-administer a fluid medicament.
The present invention is particularly, but not exclusively, useful
as a system and method for conveniently self-administering an
injection without ever subjecting the user to a visual
confrontation with the needle.
BACKGROUND OF THE INVENTION
[0003] Injectable drugs are necessary for numerous medical reasons,
and they are typically used in a wide variety of applications.
Consequently, various types of drug delivery systems have been
developed to meet the many diverse needs of particular medical
procedures. With any injectable drug delivery system, however, both
physical and psychological implications are involved. Both are
important, and both deserve consideration.
[0004] In general, all injectable drug delivery systems require
some mechanical device or system that will drive or force a liquid
into the body of a person or animal. Typically, this can be done in
either of two ways. One way is to use a hypodermic needle. The
other requires the use of a so-called needleless injector that
relies on a liquid jet to create a hole in the skin. The liquid
(i.e. fluid medicament) is then forced through the hole and into
the body. Although needleless injectors are particularly
efficacious for subcutaneous injections, they typically require
excessive power to achieve the depth normally required for many
intramuscular injections. With the above in mind, the focus here is
on drug delivery systems that require the use of a hypodermic
needle.
[0005] The physical implications that are involved when a
hypodermic needle is used with an injectable drug delivery system
pertain primarily to the needle itself. The length, the diameter
and the needlepoint characteristics of a hypodermic needle are all
obvious considerations in this context. Collectively, during the
development of an injectable drug delivery system, these
considerations must be engineered to: 1) establish the proper depth
of an injection; 2) avoid a tissue compression, that will either
cause a deep injection or result in needlepoint deformation due to
bone contact (i.e. "fish hook"); 3) minimize the dangers of
handling needles; and 4) allow for effective insertion of the
needle into the body. An improper engineering of some, or all, of
these considerations may affect drug absorption rates or cause
pain. Apart from these considerations, however, the psychological
implications that result from using a hypodermic needle may be even
more profound. This is particularly so when the fluid medicament is
to be self-administered.
[0006] Like the physical implications noted above, the
psychological implications that are involved when a hypodermic
needle is used with an injectable drug delivery system pertain
primarily to the needle. Needle anxiety is real. For instance, many
patients have a natural aversion to even the sight of a needle.
Further, this aversion frequently evokes fear of injection site
reactions (e.g. pain and bruising) that may, or may not, be real.
And, when the injection needs to be self-administered, the task
itself will often cause a hesitation or paralysis on the part of
the user that prevents accomplishing a proper injection. In this
context, it is known that "needle anxiety" has caused some patients
to unnecessarily delay the beginning of a therapy regime for
extended periods of time (e.g. several years).
[0007] Several attempts have been made to overcome many of the
aforementioned implications that are associated with injectable
drug delivery systems. For one, there have been efforts to provide
so-called auto-injectors that will automatically drive a needle
attached to a syringe into the skin to perform an injection.
Typically, this is a push-button operation that is accomplished
without any direct manipulation of the injector's drive mechanism.
Nevertheless, prior to use, auto-injectors invariably involve many
complicated steps for set-up. And, after use, they require special
disposal procedures for the needle. Unfortunately, these operations
typically expose the user to a visual contact with a needle that
can trigger "needle anxiety." Also, injections with an
auto-injector can be perceived to be more painful than a regular
syringe injection due to the auto-injector's response to the drive
mechanism actuation. Further, auto-injectors are typically not
configured to conveniently provide for the sequence of multi-dose
injections that may be required for many treatment regimes.
[0008] In light of the above, it is an object of the present
invention to provide an auto-injector that is convenient to use and
that requires minimal manipulation before, during, and after an
injection. Another object of the present invention is to provide an
auto-injector that overcomes needle anxiety by keeping the
needle(s) hidden from patient-view at all times. Still another
object of the present invention is to provide an auto-injector that
conveniently uses a "clip" or "magazine" of sterile needles to
eliminate operating steps, and to allow a patient to follow a
multi-dose treatment regime wherein a new sterile needle is
automatically provided for each injection. Yet another object of
the present invention is to provide an auto-injector that
automatically captures used needles and stores them out-of-sight
for a subsequent safe and simple disposal with regular trash.
Another object of the present invention is to provide an
auto-injector that is easy to use, is relatively simple to
manufacture, and is comparatively cost effective and provides a
comfortable injection.
SUMMARY OF THE INVENTION
[0009] In accordance with the present invention, an auto-injector
is provided that is effectively self-contained inside the interior
of a housing. The intent here is to keep all operational components
of the auto-injector, and most importantly its needle, out-of-sight
and hidden from the view of the user. As envisioned for the present
invention, this concealment of the needle is accomplished before,
during and after an injection. To do this, the needles that are to
be used with the auto-injector can be preloaded and supplied inside
a casement (magazine, drum, etc.) for insertion into or for
attachment to the auto-injector. The needle casement can then be
used, and subsequently discarded as a unit without the user ever
seeing or handling any of the needles. Some additional benefits of
the present invention are also noteworthy. Specifically, with a
completely enclosed operation, there is increased safety when using
the auto-injector of the present invention. Moreover, each needle
is used only once. This fact, alone, helps prevent contamination
and insures that the structural integrity and lubricity of each
needle are maintained until there is an actual use of the
needle.
[0010] Structurally, the auto-injector of the present invention is
characterized by an external housing that encloses many operational
components in its interior. In particular, a replaceable fluid
reservoir (e.g. cartridge) can be mounted on the housing to provide
a fluid medicament for injections into the user. As intended for
the present invention, the fluid reservoir may contain either a
single dose of the desired fluid medicament, or multiple doses of
the medicament. Also mounted onto the housing is a magazine, or
clip, that holds a plurality of sterile needles. Further, a drive
mechanism for inserting a needle into the patient is mounted in the
interior of the housing. These components then interact with each
other inside the housing via a connector and a needle holder.
Specifically, the needle holder is used to operationally position
the needle for connection with the connector, and the connector is
used to connect the needle in fluid communication with the fluid
reservoir. The needle/connector combination then cooperates with
the drive mechanism to insert the needle into the user.
[0011] As envisioned for the present invention, the needle will
typically be an elongated hypodermic needle that has both a sharp
distal end and a sharp proximal end. Additionally, the needle will
include a circular collar that is mounted on the needle between its
proximal and distal ends. More specifically, the collar will
preferably be disk shaped and will extend radially from the axis of
the hypodermic needle.
[0012] In detail, the connector of the present invention includes a
fluid transfer section that is formed with a fluid chamber that has
an input port and an output port. A septum, that is preferably made
of an elastomeric material, is used to cover the output port and
provide for fluid communication with the fluid chamber when it is
penetrated. On the other hand, the input port is connected to a
flexible hose that is provided to join the fluid chamber of the
transfer section in fluid communication with the fluid medicament
reservoir.
[0013] The needle holder that is used for the present invention can
generally have either of three embodiments. In one embodiment, the
holder is positioned in the interior of the housing and it is
substantially cylindrical-shaped. It will also define at least
three separate stations and, as the holder is rotated inside the
housing, it will assume three different operational orientations.
Specifically, during a rotation, each station will sequentially
move from a position where it retrieves a sterile needle from the
magazine, to a second position where the needle is presented for
engagement with the connector, and then to a third position where
the used needle is placed in storage. In another embodiment, the
holder is positioned inside the housing to move a sterile needle
along predetermined paths. Specifically, this involves moving a
needle from the magazine, along a first path, and into a position
for engagement with the connector. After the needle has been used,
the holder then moves the needle along a second path to a storage
location inside the housing. With this embodiment, the holder
sequentially handles each needle individually. In yet another
embodiment, the holder can be a cassette that is pre-loaded with a
plurality of needles. The cassette can then be loaded onto the
housing and rotated to sequentially position a needle for
engagement with the connector.
[0014] In operation, the user of the auto-injector (i.e. patient)
positions the housing of the auto-injector against his/her body at
the desired injection site. The user then pushes a button and waits
a few seconds while the injection is performed. The housing is then
removed from the injection site. At no time does the user see a
needle during this operation.
[0015] Inside the housing, before the user pushes the button to
initiate operation of the auto-injector, the needle holder
positions a sterile needle at a location in the housing for
engagement with the fluid transfer section of the connector. Once
the needle is so positioned, the user pushes the button to initiate
operation and the drive mechanism releases a drive rod that is
accelerated into contact with the fluid transfer section. The
consequent transfer of momentum causes the proximal end of the
needle to penetrate through the septum of the transfer section to
establish fluid communication between the needle and the fluid
reservoir. Further, in addition to the momentum that is transferred
from the drive mechanism, forces from the drive rod can also cause
the needle to be inserted into the patient for performing the
injection. Once the needle is inserted into the patient (user), a
plunger is advanced into the fluid reservoir to expel a dose of
fluid medicament therefrom through the connector and needle, and
into the patient. The needle is then subsequently withdrawn from
the patient (user) and is moved by the needle holder for storage.
At this point, another needle can be positioned at the location for
another injection operation.
[0016] It is to be appreciated that the collar on the needle can be
caused to interact with the housing during an operation of the
auto-injector to limit the depth to which the needle will penetrate
into the patient (user). It is also to be appreciated that the
auto-injector of the present invention may include a vacuum system
that can be activated to stabilize the skin of the patient at the
injection site, to thereby provide for a more predictable
injection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The novel features of this invention, as well as the
invention itself, both as to its structure and its operation, will
be best understood from the accompanying drawings, taken in
conjunction with the accompanying description, in which similar
reference characters refer to similar parts, and in which:
[0018] FIG. 1 is a view of a patient using an auto-injector in
accordance with the present invention;
[0019] FIG. 2 is a schematic diagram of the operational components
of the auto-injector of the present invention;
[0020] FIG. 3 is a perspective view of a needle in accordance with
the present invention;
[0021] FIG. 4 is a top plan view of an embodiment of a needle
holder for use with the present invention;
[0022] FIG. 5 is a top plan view of an alternate embodiment of a
needle holder for use with the present invention;
[0023] FIG. 6 is a perspective view of another alternate embodiment
of a needle holder for use with the present invention;
[0024] FIG. 7 is a cross-section view of a connector for use with
the present invention;
[0025] FIG. 8A is an elevation view of the drive mechanism, needle
and connector, in combination with the fluid reservoir of the
present invention (with portions shown in cross-section for
clarity) prior to an injection; and
[0026] FIG. 8B is an elevation view of the same components shown in
FIG. 8A during an injection.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring initially to FIG. 1, an auto-injector 10 in
accordance with the present invention is shown being used by a
patient (user) 12 for a self-administration of a fluid medicament.
As can be seen in FIG. 1, the auto-injector 10 includes a
push-button 14 that extends from the external housing 16 of the
auto-injector 10 to be depressed by the user 12 to initiate an
injection. As envisioned for the present invention, all of the
operational components of the auto-injector 10 are maintained
out-of-sight, inside the housing 16.
[0028] Referring now to FIG. 2 it will be seen that the internal
components located in the interior 17 of the housing 16 of the
auto-injector 10 include a controller 18 that is connected with the
push-button 14. In turn, the controller 18 is connected to a drive
mechanism 20, to a fluid reservoir (e.g. a fluid medicament
cartridge) 22 and, optionally, to a vacuum system 24. As envisioned
by the present invention, the controller 18 may be an electronic
micro-computer of a type well known in the pertinent art. In any
event, the purpose of the controller 18 is to coordinate the
respective operations of the drive mechanism 20, the fluid
reservoir 22, the vacuum system 24 and the needle holder 28.
[0029] FIG. 2 also shows that the drive mechanism 20 is directly
involved with the operations of a connector 26 and a needle holder
28. To understand the structure and inter-cooperation of these
components, however, it is necessary to structurally understand the
needle unit (i.e. needle) 30 that is to be manipulated by these
components. For this purpose, refer to FIG. 3. There it will be
seen that a needle unit 30 includes an elongated, hollow hypodermic
tube 32 that has a sharp proximal end 34 and a sharp distal end 36.
Further, the needle unit 30 also includes a collar 38 that is
positioned and affixed on the tube 32 intermediate the ends 34 and
36. More specifically, the collar 38 is generally disk-shaped, and
it extends in a radial direction from the axis that is defined by
the hypodermic tube 32. FIG. 3 also shows that the distal end 36 of
the tube 32 is located at a distance "l" from the collar 38.
[0030] In FIG. 4 an embodiment of the needle holder 28 is shown,
and is generally designated 40. This particular embodiment 40 of
the needle holder 28 is provided to move a needle unit 30 from a
magazine 42, and to then subsequently move it to a storage location
44. To do this, the embodiment 40 includes an arm 46 that rotates
about a point 47. A grip 48 is located at one end of the arm 46.
Thus, as the arm 46 is rotated back and forth in the direction of
the arrows 50, the grip 48 can, in sequence, retrieve a needle unit
30 from the magazine 42 and then move it along a path 52 to a
location (shown as needle unit 30'). At this location, the needle
unit 30' is positioned to cooperate with the connector 26. After
its cooperation with the connector 26, needle unit 30' is then
moved by the grip 48 along a path 54 to the storage location 44
(i.e. needle unit 30'') where it will be stored for subsequent
disposal.
[0031] FIG. 5 shows another embodiment of the needle holder 28 that
is generally designated 56. For the embodiment 56 of the needle
holder 28, a carousel 58 is employed to move the needle unit 30
into location for cooperation with the connector 26. More
specifically, for the embodiment 56 a needle unit 30 is retrieved
from the magazine 42 and moved along path 52 onto the carousel 58.
The carousel 58 then rotates in the direction of the arrow 60 to
the location of needle unit 30' where it cooperates with the
connector 26 (see FIG. 7). After its cooperation with the connector
26, the needle unit 30' is then moved by the carousel 58 for
further movement along a path 54 to the storage location 44 (shown
as needle unit 30''). There it will be stored for subsequent
disposal.
[0032] In FIG. 6, a cassette 61 is shown as yet another embodiment
of the needle holder 28. Specifically, the cassette 61 is generally
cylindrical shaped, as shown, and it is formed with a plurality of
receptacles 63. As intended for the present invention, individual
needle units 30 can be pre-loaded into respective receptacles 63 of
the cassette 61, prior to engaging the cassette 61 with the housing
16. When used, the cassette 61 is rotated about the axis 65 to
present an individual needle unit 30 at the location for
cooperation with the connector 26. Thus, the cassette 61
effectively combines the functionality of the needle holder 28, the
magazine 42 and the storage 44 into a single structure. It is to be
appreciated that all of the embodiments of the needle holder 28
(i.e. embodiments 40 and 56, as well as cassette 61) are unitary
components of the auto-injector 10. As such, they can be
selectively engaged with the auto-injector 10 and, along with the
spent needle units 30, individually disposed of after they have
been used.
[0033] Respective structures for the fluid reservoir 22, for the
drive mechanism 20, and for the connector 26 will be best
appreciated with reference to both FIG. 7 and FIG. 8A. Considering
the fluid reservoir 22 first, it will be seen that the reservoir 22
includes a vial 62 for holding a fluid medicament 64 therein. A
septum 66, at one end of the vial 62, is provided to establish
fluid communication with the reservoir 22 whenever it (i.e. the
septum 66) is penetrated. It will be appreciated, however, that any
other mechanism well known in the pertinent art for establishing a
fluid connection can be used for this purpose, such as a Luer
fitting. The fluid reservoir 22 also includes a bung 67 that can be
advanced by a plunger 68 into the vial 62 for purposes of expelling
fluid medicament 64 from the reservoir 22 through a penetrated
septum 66. As envisioned for the present invention, the fluid
reservoir 22 can be a pre-filled cartridge that can hold either
one, or multiple doses of the fluid medicament 64. Further, the
plunger 68 can be calibrated to establish a specific dosage of
fluid medicament 64, each time it advances the bung 67.
[0034] The drive mechanism 20 for the auto-injector 10 is shown in
FIG. 8A to include a drive rod 70 that is selectively propelled by
a compressed spring 72 in a linear direction indicated by the arrow
74. It will be appreciated by the skilled artisan that the actual
mechanism for propelling the drive rod 70 can vary. In this
context, the spring 72 is only exemplary. It is important for the
present invention, however, that the propulsion of the drive rod 70
by the drive mechanism 20 develops a predetermined momentum for the
drive rod 70 (see OPERATION below).
[0035] Referring specifically to FIG. 7, it will be seen that the
connector 26 includes a fluid transfer section 76 that is formed
with a fluid chamber 78. Further, the fluid transfer section 76 has
an input port 80 to the fluid chamber 78, and it has an output port
82 that is covered by a septum 84. FIG. 7 also shows that the
connector 26 includes a flex hose 86 that has one end connected for
fluid communication with the input port 80 of the fluid transfer
section 76. As also shown, the other end of the flex hose 86 is
fitted with a spike 88 that can be used to penetrate the septum 66
of the fluid reservoir 22. For another aspect of the present
invention, FIG. 8A shows that the housing 16 of auto-injector 10
can be formed with a vacuum depression 90 that is placed in fluid
communication with the vacuum system 24 (see FIG. 2) via a vacuum
hose 92.
Operation
[0036] In the operation of the auto-injector 10 of the present
invention, after setting a desired dose of the fluid medicament 64
to be delivered, the user (patient) 12 will position the housing 16
against an injection site 94. The user 12 then depresses the
push-button 14. After a predetermined time interval, the user 12
removes the auto-injector 10 from the injection site 94, and the
injection of fluid medicament 64 into the user (patient) 12 has
been completed. At no time, either before, during or after an
injection, is any part of a needle unit 30 ever visible to the user
12. Furthermore, other than an earlier loading of the fluid
reservoir 22, engaging the reservoir 22 with connector 26, and
loading a magazine 42 of needle units 30, only a dose setting may
be required before the auto-injector 10 is used. There is nothing
for the user 12 to do after the injection has been completed
except, perhaps, to put a cover (not shown) over the housing
16.
[0037] Referring back to FIG. 2, it will be appreciated that as the
user 12 depresses the push-button 14, several mechanisms inside the
housing 16 are sequentially activated by the controller 18. For
one, the needle holder 28 (with either embodiment 40 or,
alternatively, embodiment 56) retrieves a needle unit 30 from the
magazine 42. The needle holder 28 then moves the needle unit 30
into the position indicated in the drawings as needle unit 30' (see
FIG. 8A in particular). Prior to this, the connector 26 has been
connected in fluid communication with the fluid reservoir 22.
Specifically, this connection is made by inserting the spike 88 on
flex hose 86 through the septum 66. At this point, with the needle
unit 30' in position, the drive mechanism 20 comes into play.
[0038] It is an important aspect of the operation of the
auto-injector 10 of the present invention, that the drive mechanism
20 propels the drive rod 70 toward the connector 26 (e.g. fluid
transfer section 76) with a predetermined momentum. Specifically,
in accordance with well known impulse and momentum considerations,
this predetermined momentum will be determined by the mass of the
drive rod 70 and its velocity (predetermined
momentum=m.sub.rodv.sub.rod). As intended for the present
invention, when the drive rod 70 impacts with the connector 26, its
momentum (m.sub.rodv.sub.rod) is then transferred to the fluid
transfer section 76 of the connector 26. Note: the flex hose 86
mechanically isolates the transfer of momentum to only the fluid
transfer section 76. This transfer of momentum will then
immediately accomplish several functions. For one, part of the
momentum is used to establish fluid communication between the fluid
transfer section 76 of the connector 26 and the needle unit 30.
This is accomplished as the proximal end 34 of the hypodermic tube
32 penetrates through the septum 84. The remaining momentum that is
now determined by the velocity (v.sub.f) of the combined mass
(m.sub.combined) of the fluid transfer section 76 and the needle
unit 30. Importantly, the velocity term (v.sub.f) of this remaining
momentum must be sufficient to cause the distal end 36 of the
needle unit 30 to penetrate into the user (patient) 12 at the
injection site 94 (see FIG. 8B). As appreciated by the present
invention, the velocity that is necessary for generating the
necessary predetermined momentum of the drive rod 70 need not
result in an excessively high velocity for the needle unit 30. To
the contrary, the intent here is to generate a so-called "light
touch" that will guarantee only that an effective penetration of
the needle unit 30 is achieved. A benefit here is that the
possibility of creating pain or bruising at the injection site 94
is minimized. Additional benefits are that by minimizing the final
momentum there is less shock to the user 12, due to reduced recoil,
and there is a reduced need for energy input.
[0039] Once the needle unit 30 has penetrated the user (patient) 12
at the injection site 94, the controller 18 will then activate the
fluid reservoir 22. Specifically, with this activation, the bung 67
is advanced into the vial 62 to expel fluid medicament 64 into the
injection site 94. When doing this, the fluid medicament 64
traverses the flex hose 86, and enters the hypodermic tube 32 of
needle unit 30 through the fluid transfer section 76. Once the
injection has been completed, the needle unit 30 is withdrawn from
the injection site 94.
[0040] The needle holder 28 then moves the needle unit 30 to
storage 44. At this point, the auto-injector 10 is rearmed and
another cycle can then be performed. Once the magazine 42 is empty
of needle units 30, it can be disposed of. Likewise, when the fluid
reservoir 22 has been emptied of fluid medicament 64, it is ready
for disposal. In some instances it may also be desirable to dispose
of the connector 26.
[0041] Further to the above disclosure, it will be appreciated that
the vacuum system 24 can be activated during a use of the
auto-injector 10 to help stabilize the auto-injector 10 at the
injection site 94 and avoid tissue compression. Specifically, when
a partial vacuum is created in the vacuum depression 90 that is
established as housing 16 is positioned against the injection site
94, skin from the user (patient) 12 will be drawn into the
depression 90 (see FIG. 8B). This will help stabilize the
auto-injector 10 during an injection without the need to push the
auto-injector 10 against the skin and, thereby, compress tissue.
Further, the depth to which the distal end 36 of needle unit 30
will penetrate into the user (patient) 12 can be controlled, and
varied as desired. In general, penetration depths of up to around
one and a half inches are considered typical. In each case, a
precise penetration depth is achieved by establishing the distance
"l" between the collar 38 and distal end 36 of the needle unit 30
(see FIG. 3). More specifically, this distance "l" of needle unit
30, and the location of an adjustable abutment 96 on the housing 16
will establish a travel limit for the collar 38 and needle unit 30.
Consequently, a precise penetration depth can be established for
the hypodermic tube 32 of the needle unit 30.
[0042] Referring again to FIG. 8A, it will be seen that the
auto-injector 10 includes a recoil mechanism 98, such as a spring,
that is positioned on the abutment 96 substantially as shown. FIG.
8A also shows that the auto-injector 10 includes a cocking
mechanism 100 that responds to instructions from the controller 18
and is used to rearm the auto-injector 10 in preparation for a
subsequent injection cycle. In operation, the recoil mechanism 98
and the cocking mechanism 100 interact with the needle unit 30 in
different ways. These different operations are, perhaps, best
appreciated by first considering FIG. 8B.
[0043] With reference to FIG. 8B it will be seen that during an
injection (i.e. after an injection cycle has been started) the
spring 98 is depressed between the abutment 96 and the collar 38 of
needle unit 30 (30'). While it is depressed, the spring 98 reacts
against the force that is being applied by the drive spring 72 and
by the drive rod 70. The depressed spring 98, however, does not
overcome the combined forces that are applied by spring 72 and
drive rod 70. Therefore, during an injection, the distal end 36 of
needle unit 30 remains inserted at the injection site 94. Indeed,
it may be desirable for the distal end 36 to remain inserted at the
injection site 94, even after the injection of fluid medicament 64
is completed. If so, the controller 18 can be programmed to delay
the activation of cocking mechanism 100 for the withdrawal of the
distal end 36 of needle unit 30 from the injection site 94. This
delay can be for any predetermined period of time (e.g. five
seconds).
[0044] As indicated above, the cocking mechanism 100 is used to
return the drive rod 70 and its drive spring 72 from their
respective positions shown in FIG. 8B (i.e. during an injection) to
those shown in FIG. 8A (i.e. preparatory to an injection). It also
happens that this action returns the fluid transfer section 76 and
the needle unit 30 to their positions shown in FIG. 8A. To help
insure that this withdrawal is accomplished without complication,
the depressed spring 98 assists in lifting the distal end 36 of
needle unit 30 from the injection site 94. The needle unit 30 can
then be separated from the fluid transfer section 76. Importantly,
the now-used needle unit 30 can be removed from its location
between the fluid transfer section 76 and the abutment 96, and
replaced with a new sterile needle unit 30. The sequence of
operation can then be repeated, until the supply of needle units 30
that has been loaded into the auto-injector 10 is exhausted.
[0045] While the particular Injection System with Hidden Needles as
herein shown and disclosed in detail is fully capable of obtaining
the objects and providing the advantages herein before stated, it
is to be understood that it is merely illustrative of the presently
preferred embodiments of the invention and that no limitations are
intended to the details of construction or design herein shown
other than as described in the appended claims.
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