U.S. patent application number 10/635366 was filed with the patent office on 2004-02-12 for stylet-free epidural catheter and thread assist device.
Invention is credited to Botterbusch, Carl, Ulrich, Don D., Vitullo, Jeffrey M..
Application Number | 20040030289 10/635366 |
Document ID | / |
Family ID | 24827179 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040030289 |
Kind Code |
A1 |
Vitullo, Jeffrey M. ; et
al. |
February 12, 2004 |
Stylet-free epidural catheter and thread assist device
Abstract
A stylet-free epidural catheter for insertion into a patient via
a needle defining proximally a needle hub and distally a needle
tip, includes a catheter having a proximal end, a distal end, and a
body connecting the ends. The body defines therealong a stiffening
section of a predetermined length disposed a predetermined distance
proximally of the distal end such that it is located generally
about an area where the body approaches a needle hub when the
distal end approaches a needle tip. The stiffening section has a
flexural stiffness at least twice that of the remainder of the
body. A thread assist device to reduce buckling of a catheter being
inserted through a needle, includes a body defining a TAD proximal
end, a TAD distal end substantially spaced apart along a
longitudinal axis from the TAD proximal end, and a TAD sidewall
connecting the TAD ends. The TAD distal end is configured and
dimensional for at least partial receipt and releasable maintenance
within a hub of a needle, and the TAD sidewall is configured and
dimensioned intermediate the TAD ends to enable axial sliding
manipulation of the catheter through the needle hub by a user. The
TAD ends substantially preclude non-axial movement of the catheter
at the TAD ends and the TAD sidewall limits non-axial movement of
the catheter between the TAD ends.
Inventors: |
Vitullo, Jeffrey M.;
(Pottstown, PA) ; Botterbusch, Carl; (Wyomissing,
PA) ; Ulrich, Don D.; (Denver, PA) |
Correspondence
Address: |
Neal L. Rosenberg, Esq.
AMSTER, ROTHSTEIN & EBENSTEIN
90 Park Avenue
New York
NY
10016
US
|
Family ID: |
24827179 |
Appl. No.: |
10/635366 |
Filed: |
August 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10635366 |
Aug 6, 2003 |
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09703892 |
Nov 1, 2000 |
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6641563 |
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Current U.S.
Class: |
604/164.01 |
Current CPC
Class: |
A61B 17/3401 20130101;
A61M 2025/0063 20130101; A61M 25/0097 20130101; A61M 25/01
20130101; A61M 25/065 20130101; A61M 2025/0007 20130101 |
Class at
Publication: |
604/164.01 |
International
Class: |
A61M 005/178 |
Claims
I claim:
1. A stylet-free catheter for insertion into a patient via a needle
defining proximally a needle hub and distally a needle tip,
comprising: a catheter having a proximal end, a distal end, and a
body connecting said proximal and distal ends; said body defining
therealong a stiffening section of a predetermined length disposed
a predetermined distance proximally of said distal end such that it
is located generally about an area where said body approaches a
needle hub when said distal end approaches a needle tip; said
stiffening section having a flexural stiffness at least twice that
of the remainder of said body.
2. The catheter of claim 1 wherein said stiffening section has a
length of about 5 cm.
3. The catheter of claim 2 wherein said stiffening section is
disposed from about 10 cm to about 15 cm proximally of said distal
end.
4. The catheter of claim 1 wherein said stiffening section extends
from about 10 cm to about 15 cm proximally of said distal end.
5. The catheter of claim 1 wherein said stiffening section has a
diameter not exceeding the diameter of the remainder of said body
by more than about 0.15 mm.
6. The catheter of claim 1 wherein said stiffening section is
formed of plastic tubing and a cured adhesive extending
circumferentially about said plastic tubing to provide a stiffening
coating.
7. The catheter of claim 6 wherein said stiffening coating is
non-tacky and wear-resistant.
8. The catheter of claim 6 wherein said stiffening coating has a
thickness not exceeding about 0.08 mm.
9. The catheter of claim 6 wherein said stiffening coating extends
in a substantially uniform thickness along said stiffening section
and about said plastic tubing.
10. The catheter of claim 6 wherein said stiffening coating
reinforces said plastic tubing of said stiffening section.
11. The catheter of claim 6 wherein said cured adhesive is
UV-cured.
12. The catheter of claim 11 wherein said cured adhesive is cured
in situ.
13. The catheter of claim 6 wherein said cured adhesive is UV-cured
in situ.
14. The catheter of claim 1 wherein said stiffening section is
formed of plastic tubing and a plastic sleeve heat-shrunk about
said plastic tubing to stiffen said plastic tubing.
15. The catheter of claim 14 wherein said sleeve is non-tacky and
wear-resistant.
16. The catheter of claim 14 wherein said sleeve has a thickness
not exceeding 0.008 cm.
17. The catheter of claim 14 wherein said sleeve extends in a
substantially uniform thickness along said stiffening section and
about said plastic tubing.
18. The catheter of claim 14 wherein said sleeve reinforces said
plastic tubing of said stiffening section.
19. The catheter of claim 14 wherein said sleeve is polyethylene
terephthalate (PET).
20. A catheter for insertion into a patient via a needle defining
proximally a needle hub and distally a needle tip, comprising: a
catheter having a proximal end, a distal end, and a body section
connecting said proximal and distal ends; said body defining
therealong a stiffening section having a length of about 5 cm. and
a diameter not exceeding the diameter of the remainder of said
catheter body by more than about 0.15 mm; said stiffening section
being disposed from about 10 cm to about 15 cm. proximally of said
distal end such that it is located generally about an area where
said body approaches a needle hub when said distal end approaches a
needle tip; said stiffening section being formed of plastic tubing
and an adhesive UV-cured in situ and extending circumferentially
about said plastic tubing to provide a stiffening coating, said
stiffening coating being non-tacky and wear-resistant and extending
in a substantially uniform thickness not exceeding 0.08 mm along
said stiffening section and about said plastic tubing to reinforce
said stiffening section; said stiffening section having a flexural
strength at least twice times that of the remainder of said
body.
21. A catheter for insertion into a patient via a needle defining
proximally a needle hub and distally a needle tip, comprising: a
catheter having a proximal end, a distal end, and a body section
connecting said proximal and distal ends; said body defining
therealong a stiffening section having a length of about 7 cm. and
a diameter not exceeding the diameter of the remainder of said
catheter body by more than about 0.15 mm; said stiffening section
being disposed from about 10 cm to about 15 cm. proximally of said
distal end such that it is located generally about an area where
said body approaches a needle hub when said distal end approaches a
needle tip; said stiffening section being formed of plastic tubing
and a plastic sleeve heat-shrunk about said plastic tubing to
stiffen said plastic tubing; said sleeve being non-tacky and
wear-resistant and extending in a substantially uniform thickness
not exceeding about 0.08 mm along said stiffening section and about
said plastic tubing to reinforce said stiffening section; said
stiffening section having a flexural strength at least twice that
of the remainder of said body.
22. In combination, the catheter of claim 1 and a needle defining
proximally a needle hub and distally a needle tip.
23. In combination, the catheter of claim 21 and a needle defining
proximally a needle hub and distally a needle tip.
24. In combination, the catheter of claim 22 and a needle defining
proximally a needle hub and distally a needle tip.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional of U.S. patent application Ser. No.
09/703,892, filed Nov. 1, 2000.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a stylet-free epidural
catheter for insertion into a patient via a needle, as well as a
thread assist device, both to reduce buckling of a catheter in and
around the needle hub, and more particularly to a combination of
such an epidural catheter and such a thread assist device.
[0003] Commonly assigned U.S. Pat. No. 5,947,940 entitled "Catheter
Reinforced to Prevent Lumenal Collapse and Tensile Failure Thereof"
is incorporated herein by reference. This patent discusses in
detail the problems associated with medical catheters, and in
particular an epidural catheter, and the need for reinforcement
thereof to meet the rigorous requirements of an epidural catheter.
The reinforcement disclosed is at least one helical reinforcing
member (preferably predominantly non-metallic) wound around the
longitudinal axis of the elongated tubular body of the catheter for
reinforcing the body to prevent radial collapse thereof during
bending and pinching thereof and to prevent longitudinal breakage
thereof under tension. Such catheters have proven to be quite
satisfactory in use and, in particular, as epidural catheters.
[0004] Nonetheless, the design of the catheter described above has
proven to be less than totally satisfactory. Typically, the use of
a stylet within the catheter is still required during the insertion
operation. From the point of view of the catheter manufacturer,
this results in additional costs, both for the manufacture of the
stylet and for the insertion of the stylet through the catheter.
From the point of view of the catheter user, an additional step in
the procedure is required to ultimately withdraw the stylet from
the catheter after the stylet has served its function of stiffening
the catheter sufficiently to allow it to enter the epidural space
(the ligamentum flavum). Due to the length of the stylet, this is a
time-consuming and laborious operation step. Furthermore, the
removed stylet is a contaminated "sharp" which must be safely and
specially disposed of in order to not expose room personnel to
additional risks of contamination.
[0005] The prior art also teaches thread assist devices (TADs)
which enter into the luer hub of the needle and preclude buckling
(non-axial or lateral collapse) of the catheter just as the
catheter distal tip is emerging from the distal end of the needle
into the epidural space, a time when buckling tends to occur due to
the additional resistance exerted by the ligaments of the epidural
cavity. The known TADs preclude buckling of the catheter in the
region of the needle hub by completely surrounding the catheter
sidewall so that there is no room in which the catheter can buckle.
On the other hand, this positioning of the TAD requires a
practitioner to move the catheter forwardly through the needle from
a point of contact (between the practitioner and the catheter)
which is disposed proximally of the needle hub; this makes it more
difficult for the surgeon to introduce a substantially straight or
linear length of the catheter into the needle hub. At the very time
that the practitioner is pressing on the catheter with his fingers
and using friction (between his fingers and the catheter) to slide
the catheter forwardly through the TAD and the needle, there is a
tendency for the practitioner to laterally deflect the catheter
before it enters the TAD so that it is no longer in axial alignment
with the needle and the TAD. Thus, the need remains for a TAD for
use with an epidural catheter (whether reinforced or not) which
enables movement of the catheter slidingly along the needle without
deflecting the catheter from the needle axis.
[0006] Accordingly, it is an object of the present invention to
provide a catheter which does not require a stylet for the
insertion operation.
[0007] Another object is to provide such a catheter which is
economical to produce.
[0008] A further object is to provide a thread assist device (TAD)
to facilitate passage of a catheter through a needle.
SUMMARY OF THE INVENTION
[0009] In one aspect, the present invention relates to a
stylet-free catheter for insertion into a patient via a needle,
wherein the needle defines proximally a needle hub and distally a
needle tip. The catheter comprises a proximal end, a distal end,
and a body connecting the proximal and distal ends. The body
defines therealong a stiffening section of a predetermined length
disposed a predetermined distance proximally of the distal end such
that it is located generally about an area where the body
approaches the needle hub when the distal end approaches the needle
tip. The stiffening section has a flexural stiffness at least twice
that of the remainder of the body.
[0010] In a preferred embodiment, the stiffening section has a
length of about 5 (preferably 7) cm, disposed from about 10 cm to
about 15 cm proximally of the distal end, and has a diameter not
exceeding the diameter of the remainder of the body by more than
about 0.15 mm.
[0011] In one preferred embodiment, the stiffening section is
formed of plastic tubing and a cured adhesive extending
circumferentially about the plastic tubing to provide a stiffening
coating. The cured adhesive preferably is UV-cured in situ. In an
alternatively preferred embodiment, the stiffening section is
formed of plastic tubing and a plastic sleeve heat-shrunk about the
plastic tubing to stiffen the plastic tubing. The sleeve is
preferably polyethylene terephthalate (PET). In both preferred
embodiments, the stiffening coating/sleeve is non-tacky and
wear-resistant, has a thickness not exceeding about 0.08 mm,
extends in a substantially uniform thickness along the stiffening
section and about the plastic tubing, and reinforces the plastic
tubing of the stiffening section.
[0012] The present invention also encompasses in combination such a
catheter and a needle defining proximally a needle hub and distally
a needle tip.
[0013] The present invention further encompasses a thread assist
device to reduce buckling of a catheter being inserted through a
needle. The TAD comprises a body defining a proximal end, a distal
end substantially spaced along a longitudinal axis form the
proximal end, and a sidewall connecting the proximal and distal
ends. The TAD distal end is configured and dimensioned for at least
partial receipt and releasable maintenance within a hub of a
needle, and the TAD sidewall is configured and dimensioned to
enable axial sliding manipulation of a catheter through the needle
hub and through the needle by a user. The TAD proximal and distal
ends substantially preclude non-axial or lateral movement of the
catheter at the TAD ends, and the TAD sidewall limits non-axial or
lateral movement of the catheter between the TAD ends. In a
preferred embodiment, the TAD sidewall is generally cylindrical but
extends no more than 180.degree. about the TAD body intermediate
the TAD proximal and distal ends to define a gap intermediate its
long edges such that a user can establish axial sliding
manipulation of the catheter through the gap and further limit
non-axial movement of the catheter between the TAD ends.
[0014] In another embodiment, the TAD sidewall extends over an arc
of no more than about 90.degree. about the TAD body intermediate
the TAD ends and is slightly bowed outwardly from the TAD
longitudinal axis for substantially the entire length of the TAD
sidewall along the catheter, thereby to increase the potential
extent of contact between the user and the catheter between the TAD
ends and thus facilitate grasping and generally axial movement of
the catheter through the TAD by the user.
[0015] The present invention also encompasses in combination such
thread assist device, a catheter, and a needle, the distal end of
the TAD being at least partially disposed in the hub of the needle,
and the catheter extending through the TAD proximal end, along the
TAD sidewall, through the TAD distal end and into the needle.
[0016] Further, the present invention specifically encompasses the
combination of such a catheter and such a TAD.
BRIEF DESCRIPTION OF THE DRAWING
[0017] The above and related objects, features, and advantages of
the present invention will be more fully understood by reference to
the following detailed description of the presently preferred,
albeit illustrative, embodiments of the present invention when
taken in conjunction with the accompanying drawing wherein:
[0018] FIG. 1 is a fragmentary exploded side elevational view of a
stylet-free epidural catheter according to the present
invention;
[0019] FIG. 2 is a sectional view thereof taken along the line 2-2
of FIG. 1;
[0020] FIG. 3 is a fragmentary assembly side elevational view of
the catheter rotated 90.degree. about its axis from FIG. 1;
[0021] FIG. 4 is a sectional view thereof taken along the line 4-4
of FIG. 3;
[0022] FIG. 5 is a sectional view thereof taken along the line 5-5
of FIG. 4;
[0023] FIG. 6 is a sectional view taken along the line 6-6 of FIG.
5;
[0024] FIG. 7 is a fragmentary exploded side elevational view of a
thread assist device according to the present invention;
[0025] FIG. 8 is a sectional view taken along the line 8-8 of FIG.
7;
[0026] FIG. 9 is a fragmentary assembly side elevational view of
the TAD rotated 90.degree. about its axis from FIG. 7;
[0027] FIG. 10 is a sectional view thereof taken along the line
10-10 of FIG. 9;
[0028] FIG. 11 is a sectional view thereof taken along the line
11-11 of FIG. 10;
[0029] FIG. 12 is a view similar to FIG. 10, but of another
embodiment of the TAD; and
[0030] FIG. 13 is a sectional view thereof taken along the line
13-13 of FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Referring now to the drawing, and in particular FIGS. 1-6
thereof, therein illustrated is a stylet-free epidural catheter
according to the present invention, generally designated by the
reference numeral 10. The catheter 10 is designed for insertion
into a patient via a needle, generally designated 12, defining
proximally a needle hub 14, distally a needle tip 16 and optionally
a pair of wings 17.
[0032] In its conventional aspects, the catheter 10 includes a
proximal end 22, a distal end 24 and a body section, generally
designated 26, connecting the proximal and distal ends 22, 24.
[0033] In its novel aspects, the body 26 of catheter 10 defines
therealong a stiffening section, generally designated 30. The
stiffening section 30 is of a predetermined length (preferably
about 5 cm) and is disposed a predetermined distance proximally of
the distal end 24 (preferably from about 10 cm to about 15 cm
proximally of the distal end) such that it is located generally
about an area where the catheter body 26 approaches the needle hub
14 when the catheter distal end 24 approaches the needle tip 16.
This is a critical point in the functioning of the epidural device
because, as the catheter distal end 24 begins to emerge from the
distal needle tip 16, it encounters resistance which must be
overcome by the surgeon sliding the catheter 10 through the needle
12. The stiffening section 30 has a diameter not exceeding the
diameter of the remainder of the body 26 by more than about 0.15 mm
so that the increase in thickness at the stiffening section 30 is
barely appreciable. As will be apparent to those skilled in the
art, the length and positioning of the stiffening section 30 may be
adjusted for use in various epidural needles (for example, needles
for different species), with the object always being that the
strengthening section will be entering the needle hub as the
catheter distal end is emerging from the needle tip.
[0034] It is a critical factor of the present invention that the
stiffening section 30 has a flexural strength (that is, it resists
non-axial or lateral bending) which is at least twice the flexural
strength of the remainder of the catheter body 26. Flexural
strength is easily measured using an Instron Tester. A minimum
doubling of the flexural strength of the stiffening section
(relative to the plastic tubing 32 alone of the remainder of the
catheter body 26) obviates the need to employ a stylet in order to
stiffen the catheter. Nonetheless, the stiffness of the stiffening
section 30 must not preclude such bending thereof as may be
necessary for it to pass through the curved needle tip 16. (Most
needle tips are curved to facilitate passage therethrough of the
catheter.) Further, the stiffening section 30 must not be so thick
that it cannot pass through the needle 12 (and especially the
needle tip 16).
[0035] The stiffening section 30 may be formed by various
mechanisms.
[0036] In a first preferred mechanism illustrated in FIG. 1, the
stiffening section 30 is formed of plastic tubing 32 (similar to
the plastic tubing of the remainder of the catheter body 26) and a
cured adhesive 34 extending circumferentially about the plastic
tubing 32 to provide a stiffening coating 36. Preferably the
stiffening coating 36 is non-tacky and is wear-resistant. The
stiffening coating 36 preferably has a thickness not exceeding
about 0.08 mm. Ideally, the stiffening coating 36 extends in a
substantially uniform thickness along the stiffening section 30 and
about the plastic tubing 32, so that it reinforces the plastic
tubing 32 of the stiffening section 30. The cured adhesive is
preferably a UV (ultraviolet)--cured adhesive tolerated by the
patient's body, and optimally it is cured in situ. In other words,
the uncured adhesive is applied about the plastic tubing 32 of the
stiffening section 30 and then cured in place using ultraviolet
light.
[0037] In a second preferred mechanism also illustrated in FIG. 1,
the stiffening section 30 is formed of plastic tubing 32 (similar
to the plastic tubing of the remainder of the catheter body 26) and
a plastic sleeve 44 heat-shrunk about the plastic tubing 32 to
provide a stiffening sleeve 46. As in the case of the stiffening
coating 36, the stiffening sleeve 46 is preferably non-tacky and
wear-resistant, has a thickness not exceeding 0.08 mm and ideally
extends in a substantially uniform thickness along the stiffening
section 30 and about the plastic tubing 32 so that the stiffening
sleeve 46 reinforces the plastic tubing 32 of the stiffening
section 30. The sleeve 44 may be made of any suitable
heat-shrinkable plastic which is tolerated by the patient's body
and provides the desired stiffening action when heat shrunk. A
preferred plastic is polyethylene terephthalate (PET).
[0038] A conventional thread assist device (TAD) 48 has a front end
which is inserted into the needle hub 14 and a rear end which is
entered by the catheter front end 24, a length of the catheter body
26, the stiffening section 30 and more of the length of the
catheter body 26.
[0039] Referring now to FIGS. 7-11 in particular, therein
illustrated is a thread assist device (TAD) according to the
present invention, generally designated by the reference numeral
50, to reduce buckling (i.e., lateral or non-axial collapse) of a
catheter being inserted through a needle 12, regardless of whether
that catheter is a catheter 10 according to the present invention
(as described hereinabove) or a conventional catheter. As the TAD
50 and stiffening section 30 serve the same function (that is, to
reduce buckling of the catheter being inserted through the needle),
typically the thread assist device finds greatest utility in use
with a conventional catheter rather than a catheter 10 according to
the present invention (as the latter typically does not require a
TAD to be used).
[0040] The TAD 50 comprises a body, generally designated 52,
defining a proximal end 54, a distal end 56, and a sidewall 60
connecting the TAD proximal and distal ends 54, 56. The TAD
proximal and distal ends 54, 56 are substantially spaced apart
along a longitudinal axis of the TAD body 52 and define respective
full cylinder passageways 55, 57 therethrough, respectively. The
distal end 56 of the TAD body 52 is configured and dimensioned for
at least partial receipt and releasable maintenance within a needle
hub 14.
[0041] The TAD sidewall 60 is configured and dimensioned
intermediate the TAD proximal and distal ends 54, 56 to enable
axial sliding manipulation of the catheter through the needle hub
14 by a user. More particularly, the sidewall 60 is generally
cylindrical, but (as best seen in FIGS. 10 and 11) extends only
about 180.degree. (and clearly no more than 270.degree.) about the
TAD body 52 intermediate the TAD proximal and distal ends 54, 56
thereof. Thus the TAD sidewall 60 defines a gap 62 intermediate the
long edges of the sidewall 60 subtending an angle of about
180.degree. (and optionally less). This gap 62 is configured and
dimensioned to enable a user to establish axial sliding
manipulation of the catheter by inserting one or more fingers (or
fingertips) through the gap 62 and against the catheter, thereby
pressing the catheter against the TAD sidewall 60. The TAD proximal
and distal ends 54, 56 substantially preclude non-axial movement of
the catheter at the TAD ends, as such TAD ends extend fully about
the circumference of the catheter portions extending therethrough.
Because the pressure of the user's finger on the catheter only
presses the catheter against the sidewall 60, the finger pressure
further limits non-axial movement (buckling) of the catheter
between the TAD ends 54, 56. The absence of any deflection of the
catheter as it is being manipulated through the needle 12
facilitates the manipulation process by ensuring a common alignment
of the longitudinal axes of the needle 12 and the catheter body
26.
[0042] Referring now to FIGS. 12 and 13, therein illustrated is a
variant, generally designated 50', of the preferred TAD embodiment
illustrated in FIGS. 7-11. The variant 50' is similar to the
embodiment 50, except that in the variant 50' the TAD sidewall 60'
defines a gap 62' subtending an angle of about 90.degree. (and
optionally less)--i.e., the sidewall 60' extends circumferentially
about the catheter over an arc of no more than about 90.degree.
about the TAD body 52 intermediate the TAD ends 54, 56.
Furthermore, in the variant 50', the TAD sidewall 60' is slightly
bowed outwardly from the TAD longitudinal axis for substantially
the entire length of the TAD sidewall 60' along the catheter. While
the TAD proximal and distal ends 54, 56 still preclude buckling of
the catheter therein, the lesser arc of the TAD sidewall 60' and
the spacing of the TAD sidewall 60' from the unstressed catheter
increases the potential extent of contact between one or more of
the user's fingers and the catheter between the TAD ends 54, 56 as
more of the catheter circumference is exposed and engageable by the
user's fingertips. Accordingly, grasping and generally axial
movement of the catheter through the variant TAD 50' by the user is
facilitated.
[0043] The TAD is preferably formed of a plastic, such as a medical
grade thermoplastic material, which preferably exhibits a low
flexural modulus in order to allow the TAD to be bent by the
practitioner's finger during the placement operation. A preferred
material is a low-density polyethylene.
[0044] While the drawing illustrates the reinforced epidural
catheter 10 in combination with a TAD 50, it will be appreciated
that the TAD 50 may be used with catheters other than the catheter
10 of the present invention.
[0045] To summarize, the present invention provides a stylet-free
catheter which is economical to produce. The present invention
further provides a thread assist device (TAD) to facilitate passage
of a catheter (whether reinforced or not) through a needle.
[0046] Now that the preferred embodiments of the present invention
have been shown and described in detail, various modifications and
improvements thereon will become readily apparent to those skilled
in the art. Accordingly, the spirit and scope of the present
invention is to be construed broadly and limited only by the
appended claims, and not by the foregoing specification.
* * * * *