U.S. patent application number 11/398430 was filed with the patent office on 2006-08-17 for catheter for neural blockades.
Invention is credited to Heinrich Pajunk, Horst Pajunk.
Application Number | 20060184219 11/398430 |
Document ID | / |
Family ID | 7670239 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060184219 |
Kind Code |
A1 |
Pajunk; Heinrich ; et
al. |
August 17, 2006 |
Catheter for neural blockades
Abstract
A catheter for neural blockades in anesthesia includes a
flexible plastic tube in which a wire is arranged for
electro-stimulation. The distal end of the wire is conductively
applied to a contact tip protruding out of the catheter. The
contact tip comprises a stopper and a cap which are positioned in
the catheter, the cap being arranged in front of the distal end of
the catheter and covering the edge of the front surface
thereof.
Inventors: |
Pajunk; Heinrich;
(Geisingen, DE) ; Pajunk; Horst; (Geisingen,
DE) |
Correspondence
Address: |
Patrick J. O'Shea;O'Shea, Getz & Kosakowski, P.C.
Suite 912
1500 Main Street
Springfield
MA
01115
US
|
Family ID: |
7670239 |
Appl. No.: |
11/398430 |
Filed: |
April 5, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10221387 |
Feb 20, 2003 |
7027873 |
|
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PCT/EP02/00049 |
Jan 5, 2002 |
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11398430 |
Apr 5, 2006 |
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Current U.S.
Class: |
607/116 ;
607/120 |
Current CPC
Class: |
A61M 19/00 20130101 |
Class at
Publication: |
607/116 ;
607/120 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2001 |
DE |
101 00 976.3 |
Claims
1. A catheter for a nerve block in anesthesia comprising: a
flexible plastic tube that forms a lumen and includes a tube
proximal end and a tube distal end; a wire in said catheter for
electrical stimulation, whose wire proximal end is electrically
contactable at the tube proximal end and which leads to a contact
tip protruding distally from said catheter, where the contact tip
is a metal part that includes a plug and a cap, wherein said plug
is insertable coaxially into the distal end of said catheter, that
said cap is disposed in front of said tube distal end and overlaps
its distal edge surface, that the cross section of said wire is
smaller than the free internal cross section of said catheter, and
said wire is connected in an electrically conducting fashion at its
wire distal end with said plug, wherein the wall of said catheter
has at least one outlet opening at its distal end area behind said
plug and the center axis of the at least one liquid outlet opening
makes an acute angle of less than 90.degree. with respect to the
center axis of said catheter in the distal direction, whereby fluid
injected into the proximal end of the tube is directed generally in
the distal direction.
2. The catheter of claim 1, wherein said plug and said cap form a
single metal part.
3. The catheter of claim 2, wherein said wire is soldered, glued,
embossed, or laser-welded to said plug.
4. The catheter of claim 3, wherein said cap is blunt and rounded,
and makes a smooth transition at its outer periphery into the outer
contour of said catheter.
5. The catheter of claim 4, wherein said cap is in the shape of a
hemisphere.
6. The catheter of claim 4, wherein a through-hole passes axially
through said plug and said cap.
7. The catheter of claim 4, where the wall of said catheter has at
least one outlet opening at its distal end area behind said
plug.
8. The catheter of claim 7, where the center axis of at least one
outlet opening makes an acute angle of less than 90.degree. with
the center axis of said catheter in the distal direction.
9. The catheter of claim 1, wherein said at least one outlet
opening comprises three outlet openings offset by 120.degree. in
the circumferential angle, and offset axially to each other.
10. The catheter of claim 1, wherein said at least one outlet
opening comprises three outlet openings offset by 120.degree. in
the circumferential direction, and offset axially to each other.
Description
PRIORITY INFORMATION
[0001] This application is a continuation of co-pending Ser. No.
10/221,387 filed Feb. 20, 2003.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to the field of catheters, and
in particular to a catheter for nerve blocks in anesthesia.
[0003] In anesthesia, for lengthy operations, postoperative pain
therapy, and treatment of chronic pain states, the nerves supplying
a specific region of the body are often blocked by an anesthetic. A
catheter is used to introduce the anesthetic, and the distal end of
the catheter is positioned as close as possible to the nerve to
achieve an optimum effect with a minimal quantity of anesthetic.
The catheter, which can remain in position for a long time if
necessary, includes a long, thin, flexible plastic tube.
[0004] To insert the catheter into the sheath or canal of the
nerve, a cannula is used to insert the catheter. U.S. Pat. No.
5,007,902 teaches replacement of such a cannula by a puncture
cannula, in which case the puncture cannula is pulled away in order
to insert the catheter. German patent DE 3643235 C1 teaches a
puncture cannula whose internal canal emerges at the side behind
the distal tip of the cannula, with the catheter being inserted and
positioned by means of this puncture cannula. Once the catheter is
in position, the cannula used for its insertion is removed.
[0005] U.S. Pat. No. 5,007,902 also teaches the use of electrical
nerve stimulation for precise positioning of the catheter. In this
case, a guide wire is inserted in the catheter, and its distal end
protrudes slightly from the distal end of the catheter. The
proximal end of the guide wire is electrically contactable for
connection of a stimulator. Using electrical simulation, the
position of the distal end of the catheter can be determined
exactly while the catheter is being inserted into the sheath or
canal of the nerve. Since the guide wire completely fills the
internal cross section of the catheter, the wire has to be removed
from the catheter as soon as the catheter is in place in order to
apply the anesthetic through the catheter. If the catheter remains
in place for a long period of time and further medication has to be
introduced, it is often necessary to check the position of the
catheter and possibly correct it. It is necessary for this purpose
to insert a guide wire once again to determine the position of the
distal end of the catheter by electrical stimulation.
[0006] It is also known that a thin wire can be disposed in the
catheter for electrical stimulation, the cross section of which is
smaller than the free internal cross section of the catheter. In
this way, the wire does not impede introduction of a liquid through
the catheter so that the wire can remain in the catheter. The
position of the wire, fixedly disposed in the catheter, can be
checked by electrical stimulation and corrected for the entire time
that it is in place. However, if the thin end of the wire protrudes
from the distal end of the catheter, there is a risk that the tip
of the wire may cause damage and injury to the nerves while the
catheter is being pushed forward. If the wire does not protrude
from the distal end of the catheter, although this risk is reduced
the electrical contact for electrical stimulation is no longer
reliably assured.
[0007] Therefore, there is a need for a catheter for a nerve block
that can be positioned by electrical stimulation, ensuring a
reliable contact for electrical stimulation and a minimal risk of
injury, and making it possible for the catheter position to be
checked at any time by electrical stimulation.
SUMMARY OF THE INVENTION
[0008] A contact tip is placed in the distal end of the catheter,
comprising a metal part inserted coaxially with a plug into the
distal end of the catheter, protruding with a cap at the distal end
of the catheter, and overlapping the edge surface thereof. For an
electrically conductive connection between this contact tip and the
proximal end, a thin wire is disposed in the catheter which is
connected in an electrically conducting fashion with the plug of
the contact tip. The contact tip with its cap forms the distal end
of the catheter. The cap provides a reliable electrical contact
over a large surface area for nerve stimulation. The blunt, rounded
cap overlapping the distal end of the catheter also avoids the risk
of injuring the nerve as the catheter slides forward. The plug
inserted into the distal end of the catheter keeps the contact tip
centered in the distal end of the catheter. The thin wire passing
through the catheter in order to connect the distal contact tip
with the proximal connector of the stimulator does not prevent a
liquid such as an anesthetic from being introduced. Electrical
stimulation is possible as the catheter is being inserted for exact
positioning and can be repeated at any time while the catheter is
in place to check, and if necessary correct, its position.
[0009] The contact tip can completely close off the distal end of
the catheter. In this case, the liquid introduced through the
catheter exits distally through outlet openings provided in the
catheter wall at its distal end area immediately behind the contact
tip. In another embodiment, the contact tip can have an axial hole
through which the liquid can pass. In this case, outlet openings in
the catheter wall are not necessary, but can be provided in order
to enlarge the outlet cross section. The outlet openings in the
catheter wall are preferably formed so that, with their center
axis, that is the outlet direction, they form an acute angle of
less than 90.degree. with the center axis of the catheter, with
this acute angle opening in the distal direction. The acute angle
can be approximately 45.degree. in one preferred embodiment. The
shape of the outlet openings at an angle in the forward direction
causes the liquid introduced through the catheter to exit in the
distal direction so that the liquid, for example an anesthetic, is
precisely applied.
[0010] These and other objects, features and advantages of the
present invention will become more apparent in light of the
following detailed description of preferred embodiments thereof, as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0011] FIG. 1 is an axial section through the distal end of the
catheter in a first embodiment;
[0012] FIG. 2 is a corresponding view of a second embodiment;
[0013] FIG. 3 is a corresponding view of a third embodiment;
[0014] FIG. 4 is a corresponding view of a fourth embodiment;
[0015] FIG. 5 is a corresponding view of a fifth embodiment;
and
[0016] FIG. 6 is a lateral view of the distal end of the catheter
without the contact tip, in partial axial section.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIG. 1 is a cross section view of a catheter 10. The
catheter 10 is a flexible tube, made for example of plastic or
polyamide. The length of the catheter 10 depends on its
application. For peripheral plexus anesthesia, the length of the
catheter 10 is approximately 400 mm, while for peridural and spinal
anesthesia a length of for example 900 mm may be used. The diameter
of the catheter 10 also depends on the application. For example, a
19G catheter has an external diameter of 1 mm and an internal
diameter of 0.5 mm. A 20G catheter has an external diameter of 0.8
mm and an internal diameter of 0.4 mm. It is possible to use a
still thinner catheter with correspondingly smaller diameters.
[0018] The catheter 10 includes a contact tip that is placed in the
distal end of the catheter 10, and is formed as a metal part. The
contact tip includes a plug 12 and a cap 14, in one piece. The plug
12 has the shape of a circular cylinder whose external diameter
corresponds to the internal diameter of the catheter 10. This makes
it possible to insert the plug 12 of the contact tip into the
distal end of the catheter 10 so that the plug 12 is held with a
snug fit in the catheter 10. The external diameter of the cap 14
corresponds to the external diameter of the catheter 10. When the
contact tip is inserted into the distal end of the catheter 10, the
plug 12 is pushed into the lumen of the catheter 10 until the cap
14 abuts the distal end surface of the catheter 10. Since the
diameter of the plug 12 corresponds to the internal diameter of the
catheter 10, the plug 12 holds the contact tip in the center at the
distal end of the catheter 10 with the cap 14 overlapping and
covering the edge surface of the catheter 10. At the outer
periphery, the cap 14 fits flush to the catheter 10 so that the cap
14 fits seamlessly into the outer periphery of the catheter 10.
[0019] For an electrically conductive connection of the contact tip
with a stimulator (not shown) connected at the proximal end of the
catheter, a thin wire 16 is disposed in the catheter 10. The
diameter of the wire 16 is considerably smaller than the internal
diameter of the catheter 10, so that a considerable portion of the
lumen of the catheter 10 remains free for a liquid to pass through.
The diameter of the wire 16 is for example 0.2 mm. The proximal end
of the wire 16 is contactable with the stimulator in a manner not
shown. The distal end of the wire 16 is connected in an
electrically conducting fashion with the plug 12 of the contact
tip, for example soldered, glued, embossed, or laser-welded. A
number of embodiments of the contact tip are described below.
[0020] In the embodiment of FIG. 1, the plug 12 and the cap 14 are
closed. The cap 14 is in the shape of a hemisphere whose curved
portion is on the distal side. The wire 16 is soldered coaxially
into a blind hole provided coaxially in the inside end surface of
the plug 12.
[0021] In the embodiment of FIG. 2, the cap 14 is also in the shape
of a hemisphere. A through-hole 18 passes through the contact tip
(i.e., through the plug 12 and the cap 14), and runs eccentrically
and axially parallel thereto. The blind hole that receives the wire
16 is located axially parallel and externally diametral to the
through-hole 18.
[0022] In the embodiment of FIG. 3, the cap 14 is also
hemispherical. The through-hole 18 passes coaxially through the
plug 12 and the cap 14. The wire 16 is soldered into a groove
formed axially in the outer periphery of the plug 12.
[0023] In the embodiment of FIG. 4, the cap 14 is in the shape of a
flat plate that extends from a smooth distal end surface starting
at the outer circumference with a radius of curvature and makes a
transition to the cylindrical circumferential surface of the
catheter 10. As in the embodiment of FIG. 3, the through-hole 18 is
coaxial and the wire 16 is set in an axial circumferential
groove.
[0024] In the embodiment of FIG. 5, the cap 14 is in the shape of a
hemisphere. The through-hole 18 is coaxial, and has a larger
diameter toward the inside end of the plug 12. A hollow bushing 20
is inserted into this enlarged section of through-hole 18, and
includes an inside wall to which the wire is electrically
connected.
[0025] If the contact tip has an axial through-hole 18, a liquid
such as an anesthetic can be added through the catheter 10 and exit
through this through-hole 18. If the contact tip is closed, as for
example in the embodiment of FIG. 1, one or more outlet openings 22
are provided in the distal end area of the catheter 10 behind the
contact tip, through which openings the liquid can exit. Such
outlet openings 22 can also be provided in cases where the contact
tip has an axial through-hole 18 to enlarge the cross section for
the added liquid to exit.
[0026] The outlet openings 22 may have any shape, cross section,
and arrangement. A design such as that shown in FIG. 6 is
preferable. In this design, the outlet openings 22 are provided in
the wall of the catheter 10 such that the center axis of the outlet
opening 22 makes an acute angle with the center axis of the
catheter 10 (e.g., an angle of 45.degree.), with this acute angle
opening in the distal direction. In this way, the liquid added is
directed distally through the outlet openings 22. Three outlet
openings 22 are provided, making angles of 120.degree. with each
other in the circumferential direction. This ensures that the
liquid added is dispensed evenly over the entire periphery of the
distal end of the catheter 10. In order for the outlet openings 22
not to weaken the wall of the catheter 10, the outlet openings 22
are preferably offset axially from each other.
[0027] Although the present invention has been shown and described
with respect to several preferred embodiments thereof, various
changes, omissions and additions to the form and detail thereof,
may be made therein, without departing from the spirit and scope of
the invention.
* * * * *