Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-02-15
2004-01-06
Look, Edward K. (Department: 3754)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S187000, C604S218000
Reexamination Certificate
active
06673049
ABSTRACT:
BACKGROUND
The present invention relates to an injection device for injecting fluid from a fluid container. It also relates to an actuator for such an injection device.
Syringe-shaped injection devices for injecting fluids have been known for some time. They contain a bushing-shaped main body which can be screwed together at approximately the centre and can be divided into two main sections:
a distal section (facing away from the patient) containing the discharge mechanism and comprising at least one rod-shaped driven member having a structured surface (e.g. a screw rod), a hollow cylindrical counter component corresponding to the driven member, provided with a structured internal sleeve (e.g. a screw nut); and
a control button; and
a proximal section (facing the patient) containing the fluid to be administered and a movable piston.
At the proximal end of the main body, a needle and a needle holder are attached, allowing the fluid to be discharged from the device; known needles of this type are for instance needles as described in WO95/01812.
The connecting member between the proximal and the distal section of the main body is the driven member, shifting the piston by the required dose in proximal direction and discharging the fluid through the needle.
Often the fluid to be injected is not directly contained in the main body but in an ampoule or container, with the fluid being stored between a piercable membrane and a piston displaceable by sliding.
Depending on the injection device, various features are expected from the discharge mechanism. There are devices allowing only a single discharge, devices allowing several discharges of the same dose and devices allowing freely selectable discharges.
For patients using injection devices allowing a change of ampoules, it is—irrespective of the complexity of the discharge mechanism—extremely difficult to wind back the driven member to the initial position in order to make the device ready for operation after the ampoule has been changed. Devices requiring the driven member to be rewound by the control button are known from WO93/16740. Devices allowing the threaded rod to be pushed back, as in publications U.S. Pat. No. 4,592,745 and EP-A-0 554 995, are more easily operated by patients. According to these prior art devices the threaded nut is spread due to the release of the distal section from the proximal section of the main body, allowing the threaded rod to move freely without any conscious operation by the patient, with screwing together of both sections of the main body after replacement of the ampoule easily causing a premature unintentional discharge of fluid. Depending on the injection device, this could also result in an incorrect dosing which, in case of certain medication, could be extremely hazardous to the patient's health.
An injection device to remedy this situation is known from applicants patent U.S. Pat. No. 6,090,080, the disclosure thereof is incorporated herein by reference. Such a known injection device is described with reference to
FIGS. 14
to
19
.
In the subsequent description, the terms proximal and distal are used in their usual medical sense, i.e. proximal=facing the patient and distal=facing away from the patient.
As shown in
FIG. 14
, the injection device comprises a bushing-shaped main body
1
which can be divided into a rear (distal) section
3
containing the tubular actuating device or discharge mechanism
7
and a front (proximal) section
2
containing a replaceable ampoule
4
and a piston
5
. A needle
6
with its distal end connected to the fluid to be administered can be screwed to the proximal end of the main body
1
. The actuating device
7
comprises a control button
8
, a threaded rod
9
with a flange
19
, a guide member
24
and a driving member
11
.
The tubular driving member
11
is rigidly connected to the control button
8
to prevent twisting. At the proximal end, the driving member
11
surrounds two threaded flanges
27
,
27
′ engaging in the thread of the threaded rod
9
.
FIG. 18
shows that the threaded rod
9
comprises two level surfaces
12
,
12
′ and apart from that is of a circular cross section, with the circular surfaces
13
,
13
′ being threaded.
The guide member
24
is rigidly connected to the distal section
3
of the main body
1
, thus preventing rotation or axial movement and is positioned in front of the driving member
11
. The aperture in the guide member
24
, through which the threaded rod
9
passes (
FIG. 19
) is of the same cross section as the threaded rod
9
—although enlarged by certain tolerances. As the guide member
24
, in contrast to the driving member
11
, is not threaded, the threaded rod
9
can be shifted through the opening of the guide member in axial direction. A rotational movement of the threaded rod
9
is therefore not possible as the guide member
24
does not allow this.
The control button
8
may be moved in axial direction or may be rotated. Where the control button is activated by being pushed in proximal direction, it will simultaneously shift the driving member
11
until its front face
14
pushes against the rear face
14
′ of the guide member.
The threaded rod
9
is connected to the driving member
11
by threaded flanges
27
,
27
′ thus allowing any axial movement of the control button
8
to be transferred. See detailed description of threaded flanges
27
,
27
′ below.
The axial movement is effected against the bias of a spring
16
, returning the actuating device
7
to its home position (FIG.
14
).
When turning the control button
8
to adjust an injection dose, the driving member
11
is also turned. This rotating movement can, however, not be transferred to the threaded rod
9
as the rod is rigidly seated in the guide member
24
. As a result of the rotating threaded flanges
27
,
27
′ in driving member
11
, the threaded rod
9
is rigidly driven forward via the threaded sections of the circular surfaces
13
,
13
′ (or backward, when reversing the rotation direction of the control button), thus bringing the flange
19
into the position required for the next injection dose to be discharged, i.e. the distance of the flange
19
from the piston
5
is respectively reduced.
By pressing the control button
8
, the actuating device
7
is moved from its home position to the end position. The flange
19
pushes thereby against the piston
5
during this operation, carrying it along the set piston travel and thus discharging the pre-set volume of injection fluid through injection needle
6
. The travel of the flange
19
from the home position to the end position of the actuating device
7
always remains the same and corresponds to a constant distance by which the flange
19
is separated from the piston
5
before setting the injection dose. This process is described in detail in WO 93/16740.
When the fluid container
4
is empty and the threaded rod
9
is therefore in the extreme proximal position, the threaded rod must be returned to the extreme distal position. The injection device according to the invention allows the threaded rod
9
to be returned by activation of an unlocking slide
32
.
FIGS. 17 and 18
show that both threaded flanges
27
,
27
′ of the driving member
11
are designed as two half-shell threaded nut sections, each provided with two cams
28
,
28
′,
29
,
29
′.
The unlocking slide
32
attached to the rear section
3
is connected to an internal spreader bushing
35
in the rear section
3
, with shifting of the unlocking slide
32
in distal direction causing the spreader bushing
35
to be shifted in distal direction.
The spreader bushing
35
surrounds the driving member
11
and comprises four vertical tracks
30
,
30
′,
31
,
31
′ (FIG.
16
), which extend towards the proximal end of the spreader bushing
35
outwardly at an angle. The tracks
30
,
30
′,
31
,
31
′ serve to accommodate the cams
28
,
28
′,
29
,
29
′ of the threaded flanges
27
,
2
Hommann Edgar
Jost Stefan
Disetronic Licensing AG
Dorsey & Whitney LLP
Fristoe Jr. John K.
Look Edward K.
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