U.S. patent application number 10/597893 was filed with the patent office on 2008-09-25 for catheter guide wire.
This patent application is currently assigned to MEDIPLUS LIMITED. Invention is credited to Robert Graham Urie.
Application Number | 20080234605 10/597893 |
Document ID | / |
Family ID | 32011657 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080234605 |
Kind Code |
A1 |
Urie; Robert Graham |
September 25, 2008 |
Catheter Guide Wire
Abstract
A catheter guidewire for facilitating introduction of a flexible
catheter into the human body (e.g., into the bladder) has a
proximal end having a first stiffness which is sufficient to
facilitate guidance of a stiff plastic expansion sheath through the
tissue. A distal end of the guide wire has a second stiffness,
substantially less than the first stiffness, to avoid damage to
internal walls of the bladder. Preferably, the guide wire
incorporates an intermediate portion having a stiffness between the
first stiffness value and the second stiffness value.
Inventors: |
Urie; Robert Graham;
(Buckinghamshire, GB) |
Correspondence
Address: |
RENNER OTTO BOISSELLE & SKLAR, LLP
1621 EUCLID AVENUE, NINETEENTH FLOOR
CLEVELAND
OH
44115
US
|
Assignee: |
MEDIPLUS LIMITED
High Wycombe, Buckinghamshire
GB
|
Family ID: |
32011657 |
Appl. No.: |
10/597893 |
Filed: |
February 11, 2005 |
PCT Filed: |
February 11, 2005 |
PCT NO: |
PCT/GB2005/000494 |
371 Date: |
May 20, 2008 |
Current U.S.
Class: |
600/585 ;
604/526 |
Current CPC
Class: |
A61M 2025/09083
20130101; A61M 2025/0915 20130101; A61M 25/09 20130101; A61M
25/0017 20130101; A61M 25/09041 20130101; A61M 2025/0188 20130101;
A61M 25/0606 20130101 |
Class at
Publication: |
600/585 ;
604/526 |
International
Class: |
A61B 5/00 20060101
A61B005/00; A61B 5/02 20060101 A61B005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2004 |
GB |
0402930.2 |
Claims
1. A guidewire for introduction into a body via a hollow needle,
comprising: a proximal end having a stiffness greater than 10 N;
and a distal end having a stiffness less than 3 N, the stiffness
being defined as the force required to produce an angular lateral
displacement of 30 degrees when applied at a distance of 10 mm
along the respective length of guidewire.
2. The guidewire of claim 1 further including an intermediate
portion having a stiffness lying between the stiffness of the
proximal end and the distal end.
3. The guidewire of claim 1 in which the distal end comprises a
coil having a central core.
4. The guidewire of claim 2 in which the distal end and the
intermediate portion comprise a coil having a central core, the
core having a first diameter in the intermediate portion greater
than a second diameter in the distal portion.
5. The guidewire of claim 4 in which the central core has a
tapering diameter in the intermediate portion towards the distal
end.
6. The guidewire of claim 1 in which the distal end extends over a
length of between 10 and 15 cm.
7. The guidewire of claim 6 in which the distal end extends over a
length of 12.5 cm.+-.1 cm.
8. The guidewire of claim 2 in which the distal end extends over a
length of between 2 and 8 cm, and in which the intermediate portion
extends over a length of between 2 and 8 cm.
9. The guidewire of claim 8 in which the distal end extends over a
length of at least 2 cm and in which the intermediate portion
extends over a length of 4 cm.+-.1 cm.
10. The guidewire of claim 1 in which the proximal end comprises a
hollow tube containing a wire core.
11. A guidewire for introduction into a body via a hollow needle,
comprising: a proximal end having a first stiffness; a distal end
having a second stiffness less than said first stiffness; and an
intermediate portion having a stiffness lying between the first and
second stiffness values.
12. The guidewire of claim 11 in which the distal end comprises a
coil having a central core.
13. The guidewire of claim 12 in which the distal end and the
intermediate portion comprise a coil having a central core, the
core having a first diameter in the intermediate portion greater
than a second diameter in the distal portion.
14. The guidewire of claim 13 in which the central core has a
tapering diameter in the intermediate portion towards the distal
end.
15. The guidewire of claim 11 in which the distal end extends over
a length of between 10 and 15 cm.
16. The guidewire of claim 15 in which the distal end extends over
a length of 12.5 cm.+-.1 cm.
17. The guidewire of claim 11 in which the distal end extends over
a length of between 2 and 8 cm, and in which the intermediate
portion extends over a length of between 2 and 8 cm.
18. The guidewire of claim 7 in which the distal end extends over a
length of at least 2 cm and in which the intermediate portion
extends over a length of 4 cm.+-.1 cm.
19. The guidewire of claim 11 in which the proximal end comprises a
hollow tube containing a wire core.
20. The guidewire of claim 1 in which the proximal end has a
stiffness adapted to facilitate the guiding of a substantially
rigid catheter sheath of diameter in the range 5 to 7 mm into the
bladder via the supra-pubic region of the human body.
21. The guidewire of claim 1 forming part of a kit comprising: a
hollow needle having an inside diameter adapted for receiving the
guidewire; and a catheter sheath having an internal diameter
adapted to receive the guidewire and to penetrate the supra-pubic
region of the human body using the proximal portion of the
guidewire as a guide, the catheter sheath having a peelable outer
skin.
22. A bladder drainage kit comprising: a guidewire having an
outside diameter less than 2 mm and having a proximal end having a
first stiffness and a distal end having a second stiffness, the
second stiffness being less than the first stiffness; a peelable
catheter sheath adapted to receive the guidewire and to penetrate
the supra-pubic region of the human body using the proximal portion
of the guidewire as a guide, the catheter sheath having an inside
diameter at its distal end approximately equal to the outside
diameter of the guidewire, and an inside diameter at its proximal
end of at least 4 mm for receiving a flexible drainage
catheter.
23. The kit of claim 22 in which the peelable catheter sheath
further includes an inner sheath for stiffening the peelable
catheter sheath during insertion into the body, the inner sheath
being withdrawable from the proximal end of the peelable catheter
sheath.
24. The kit of claim 22 in which the guidewire has a diameter at
its distal end in the range 750 to 1000 microns.
25. A method for introducing a catheter into the bladder of the
human body in the supra-pubic region comprising the steps of:
introducing a needle into the bladder via the supra-pubic region,
the needle having an outside diameter less than 2 mm; inserting a
guidewire having an outside diameter less than 2 mm into the
bladder through an internal bore of the needle; withdrawing the
needle over the guidewire; introducing a peelable catheter sheath
into the bladder over the guidewire, the catheter sheath having a
distal end of outside diameter less than approximately 2 mm and a
proximal end having an outside diameter of at least 4 mm;
withdrawing the guidewire through the catheter sheath; inserting a
flexible catheter into the bladder through the catheter sheath; and
peeling away the catheter sheath from the flexible catheter leaving
the flexible catheter in situ.
26. (canceled)
Description
[0001] The present invention relates to guide wires for the
insertion of catheters into the human or animal body and in
particular, though not exclusively, to guide wires suitable for the
insertion of the catheter into the bladder.
[0002] Insertion of a flexible catheter into the human bladder via
the supra-pubic region can present particular problems. In one
conventional technique, a large bore needle having an internal
diameter capable of receiving the flexible catheter is used to
penetrate the skin, underlying tissue and bladder. A flexible
catheter is then introduced into the needle and inserted into the
bladder, following which the needle may be withdrawn. This requires
the use of a needle having large diameter sufficient to accommodate
a catheter and of sufficient strength to penetrate the relative
tough supra-pubic tissue area. This requires the use of a needle
having an outside diameter that is significantly larger than the
outside diameter of the flexible catheter (which itself is
typically approximately 4 or 5 mm), thereby forming a hole in the
tissue significantly larger than strictly necessary. Great care has
to be exercised by the clinician introducing the needle to avoid
over- or under-penetration of the needle.
[0003] In another conventional technique, a trocar having a stiff
penetrative tip (e.g. of medical grade stainless steel) and a stiff
outer plastic sheath is inserted into the bladder through the
supra-pubic region. The trocar is then withdrawn through the
sheath, leaving the sheath in situ, penetrating the bladder through
the supra-pubic region. A flexible catheter is then introduced into
the bladder through the sheath. The plastic sheath is of the
peelable variety, so that once the flexible catheter is introduced
into the bladder, the sheath can be split along its entire length,
stripped away from the flexible catheter and removed from the body.
This leaves the flexible catheter in situ. A potential drawback
with this technique is that the initial penetration of the
supra-pubic region is, like the previously described technique,
performed with a penetrative instrument having an outside diameter
of similar dimensions to the flexible catheter that is eventually
introduced (e.g. of the order of 5 mm or so). Therefore, again, the
clinician must exercise great care to avoid over-penetration of the
bladder and potential damage to the opposite bladder wall.
[0004] The present invention seeks to provide an improved method
and apparatus for insertion of a flexible catheter into a human or
animal body. In one aspect, the invention seeks to provide a
guidewire technique to overcome some or all of the disadvantages
associated with the prior art.
[0005] According to one aspect, the present invention provides a
guidewire for introduction into a body via a hollow needle,
comprising: [0006] a proximal end having a stiffness greater than
10 N; and [0007] a distal end having a stiffness less than 3 N,
[0008] the stiffness being defined as the force required to produce
an angular lateral displacement of 30 degrees when applied at a
distance of 10 mm along the respective length of guidewire.
[0009] According to another aspect, the present invention provides
a guidewire for introduction into a body via a hollow needle,
comprising: [0010] a proximal end having a first stiffness; [0011]
a distal end having a second stiffness less than said first
stiffness; and [0012] an intermediate portion having a stiffness
lying between the first and second stiffness values.
[0013] According to another aspect, the present invention provides
a method for introducing a catheter into the bladder of the human
body in the supra-public region comprising the steps of: [0014]
introducing a needle into the bladder via the supra-pubic region,
the needle having an outside diameter less than 2 mm; [0015]
inserting a guidewire having an outside diameter less than 2 mm
into the bladder through an internal bore of the needle; [0016]
withdrawing the needle over the guidewire; [0017] introducing a
peelable catheter sheath into the bladder over the guidewire, the
catheter sheath having a distal end of outside diameter less than
approximately 2 mm and a proximal end having an outside diameter of
at least 4 mm; [0018] withdrawing the guidewire through the
catheter sheath; [0019] inserting a flexible catheter into the
bladder through the catheter sheath; and [0020] peeling away the
catheter sheath from the flexible catheter leaving the flexible
catheter in situ.
[0021] According to another aspect, the present invention provides
a bladder drainage kit comprising: [0022] a guidewire having an
outside diameter less than 2 mm and having a proximal end having a
first stiffness and a distal end having a second stiffness, the
second stiffness being less than the first stiffness; [0023] a
peelable catheter sheath adapted to receive the guidewire and to
penetrate the supra-pubic region of the human body using the
proximal portion of the guidewire as a guide, the catheter sheath
having an inside diameter at its distal end approximately equal to
the outside diameter of the guidewire, and an inside diameter at
its proximal end of at least 4 mm for receiving a flexible drainage
catheter.
[0024] Embodiments of the present invention will now be described
by way of example and with reference to the accompanying drawings
in which:
[0025] FIG. 1 shows an axial cross-section of a guidewire according
to a preferred embodiment of the present invention;
[0026] FIG. 2 shows an axial cross-section of a centre wire of the
guidewire of FIG. 1;
[0027] FIG. 3 shows a side view of the complete guidewire of FIG.
1; and
[0028] FIG. 4 shows a schematic diagram illustrating a needle, a
plastic catheter sheath with peelable outer skin and catheter,
useful in explaining a method of use of the guidewire of the
present invention.
[0029] A feature of the method of the present invention is that a
guide wire can be used to significantly reduce the diameter of
needle or trocar required to penetrate the bladder. This is
particularly significant in the supra-pubic region where the tissue
is particularly tough. In the preferred technique, a small diameter
needle (e.g. of the order of 1 mm outside diameter) is inserted
into the bladder in the supra-pubic region. The relatively small
diameter needle is much easier to control during penetration of the
tissue.
[0030] A thin guidewire is then introduced into the bladder via tie
needle, such that it extends into the bladder. The needle is then
withdrawn over the guidewire, leaving the guidewire in place. A
stiff plastic sheath having a distal end which tapers down to a
diameter similar to that of the guidewire is introduced into the
bladder through the skin and tissue using the guidewire as a guide.
This expands the existing hole in the tissue. A flexible catheter
is then introduced into the plastic sheath and thereby into the
bladder. The plastic sheath is of the peelable variety, so that
once the flexible catheter is introduced into the bladder, the
sheath can be split along its entire length, stripped away from the
flexible catheter and removed from the body. This leaves the
flexible catheter in situ. A significant advantage of this
procedure is that the initial penetration of the supra-pubic region
is by way of small diameter needle; the expansion of the initial
hole can then be performed under the control of a guidewire.
[0031] In order to successfully perform this procedure, the
guidewire must have a high degree of stiffness in order to
facilitate and guide the penetration, into the body, of the
relatively larger plastic sheath. Otherwise the pressure being
applied on the plastic sheath to displace tough tissue will distort
the guidewire. This high stiffness in turn again increases the
likelihood of internal damage to the bladder caused by
over-insertion of the guidewire, such that the distal end thereof
collides with an opposite internal wall of the bladder. Therefore,
the clinician must exercise great care not to over-insert the
guidewire, despite significant variations in physique of different
patients (e.g. the depth and stiffness or muscle tone of tissue to
be penetrated).
[0032] With reference to FIG. 1 there is shown a guidewire 1 of a
preferred embodiment. The guidewire comprises outer tubing 2,
preferably formed from stainless steel, which is filled with a
solid core 3, also preferably formed from stainless steel. The
outer tubing 2 extends from a proximal end 5 of the guidewire 1 to
a first intermediate position 6 where it is welded, brazed or
otherwise fixed or bonded to a tightly would coil 4 of
substantially the same outside diameter as the outer tubing 2. The
coil 4 extends from the first intermediate position 6 to a distal
end 9 of the guidewire 1.
[0033] The solid core 3 extends throughout the outer tubing 2 and
extends beyond the first intermediate position to the distal end 9
of the guidewire. At the first intermediate position 6, or slightly
beyond it at a second intermediate position 7 towards the distal
end 9, the solid core 3 commences a taper. The taper ends at a
third intermediate position 8. The solid core 8 terminates at the
distal end in a `mushroom` configuration where it is welded, brazed
or otherwise fixed or bonded to the tightly wound coil 4.
[0034] As is particularly illustrated in FIG. 1, the guidewire 1
therefore provides three distinct portions. These are: a first
(`proximal`) portion 11 extending from the proximal end 5 to the
first intermediate position 6; a second (`intermediate`) portion 12
extending from the first intermediate position 6 to the third
intermediate position 8; and a third (`distal`) portion 13
extending from the third intermediate position 8 to the distal end
9.
[0035] The combination of the outer tubing 2, the coil 4 and the
solid core 3 effectively provides a guidewire 1 having a first
stiffness at the proximal end (and generally extending throughout
the proximal portion 11 to the first intermediate position 6), a
second stiffness at the distal end 9 (and generally extending
throughout the distal portion 13 to the third intermediate position
8) in which the second stiffness value is significantly less than
the first stiffness value. In the intermediate portion 12, the
stiffness value lies between that of the first and second stiffness
values and may generally vary over the length thereof.
[0036] In the following preferred values, the stiffness is defined
as the force required to produce an angular lateral displacement of
30 degrees when applied at a distance of 10 mm along the respective
length of guidewire. Preferably, the stiffness of the proximal
portion 11 is in excess of 10 N, and more preferably lies within
the range 15 to 20 N. Preferably, the stiffness of the distal
portion 13 is less than 3 N, and more preferably lies within the
range 0.2 to 1 N. Preferably, the stiffness of the intermediate
portion 12 lies in the range between that of the adjacent proximal
and distal portions, and preferably it has a gradual or stepped
reduction in stiffness over the length of the intermediate portion
12. In preferred embodiments, the stiffness of the intermediate
portion lies in the range 5 N to 8 N.
[0037] In the preferred arrangement as shown, the outer tubing has
an outside diameter approximately 0.0355 inch or 0.0360 inch (900
or 915 microns). The outer tubing has a length of 30 cm. The coil
has an outside diameter of approximately 0.0370 inch (940 microns)
and a coiled length of approximately 12.5 cm. The solid core 3 has
a maximum outside diameter (in the proximal portion) of
approximately 0.020 inch (500 microns) and an overall length of
approximately 42 cm. The solid core 3 has a diameter tapering to
approximately 0.006 inch (150 microns) at the third intermediate
position 8 and a length of distal portion of approximately 21 mm.
The solid core 3 may taper in the distal portion 13 down to a
diameter of between approximately 0.0023 inch and 0.0033 inch (58
to 84 microns).
[0038] In another arrangement, the outer tubing and coil have an
outside diameter of approximately 750 microns. In a general aspect,
the guidewire has an outside diameter of less than 2 mm and
preferably less than or equal to 1 mm, e.g. in the range 750 to
1000 microns.
[0039] It will be understood that these dimensions may need to be
varied in order to provide utility in different regions of the body
and possibly for different patient morphology.
[0040] More generally, the guidewire 1 preferably has a distal end
which extends over a length of between 10 and 15 cm, and more
preferably over a length of 12.5 cm.+-.1 cm. Preferably, the distal
end comprises the distal portion 13 and the intermediate portion
12. In another general arrangement, the guidewire 1 has a distal
portion that extends over a length of between 2 and 8 cm and an
intermediate portion that extends over a length of between 2 and 8
cm. More preferably, the distal end extends over a length of at
least 2 cm and the intermediate portion extends over a length of 4
cm.+-.1 cm.
[0041] The materials used are preferably 304 stainless steel
throughout although other clinical grade materials may be
considered.
[0042] Preferably, the guidewire is provided with reference
markings at predetermined positions along its length. With
reference to FIG. 3, the guidewire 1 preferably includes a first
reference mark 30 at a distance of 340 mm from the distal end 5 and
a second reference mark 31 at a distance of 215 mm from the distal
end. The function of the reference marks will become apparent from
the description hereinafter.
[0043] With reference to FIG. 4, in a preferred arrangement, tie
guidewire is deployed in the following manner.
[0044] A needle 40 of gauge 1 mm and length 7 mm is introduced into
the bladder 41 through the supra-pubic tissue 42. The guidewire 1
is introduced into the bladder 41 through the needle. An important
feature of the guidewire is that the distal portion 13 is
relatively flexible with minimal stiffness (sufficient to allow
convenient introduction into and through the needle) and is unable
to cause damage to the internal walls of the bladder 41, especially
at a location 43 opposite to the point of entry of the needle 40.
Preferably, the intermediate portion 12 has a sufficient increase
in stiffness over the distal portion 13 to provide tactile feedback
to the clinician. In other words, when the guidewire has been
passed into the bladder to an extent that the intermediate portion
12 reaches the opposite bladder wall 43, its collision with the
wall will be evident to the clinician by simple change in
resistance to further motion.
[0045] Despite the increased stiffness of the guidewire at that
point, where the intermediate portion reaches the bladder wall 43,
the existence of the more flexible (and now curved) distal portion
13 prevents damage to the bladder walls.
[0046] At this point, the clinician ceases further entry of the
guidewire, and withdraws the needle 40 over the proximal end 11 of
the guidewire 1 still outside the body. Following removal of the
needle, a stiff plastic sheath, or preferably a pair of coaxial
sheaths 44, 45, are slid over the guidewire 1 from its proximal
end, preferably up to the point where the first or second reference
mark appears (depending upon the type of sheath being used). The
stiff plastic sheaths 44 and 45 have a tapered end 46 adapted to
form a snug sliding fit over the guidewire 1, ie. having an inside
diameter slightly larger than that of the outer tube 2 and coil
4.
[0047] The stiff plastic sheath provides a gradual increase in
diameter increasing from approximately 1.2 mm outside diameter at
its distal end 46 to 6 mm outside diameter for the main body
portion 47. In the preferred embodiment, the outer sheath 44 of the
coaxial pair of sheaths is formed from a relative thin and
frangible plastics material and includes two lugs 48 at the
proximal end. The inner sheath 45 is rather more robust and
provides the mechanical strength required.
[0048] In use, the plastic sheaths are adapted to be guided by the
guidewire into the tissue to expand the hole already formed by the
needle. Particularly in the supra-pubic region, entry of the
plastic sheath encounters significant resistance, increasing the
dimension of hole in the tissue from the needle diameter (e.g. 1 mm
to 6 mm). An important feature of the guidewire described herein is
to provide a stiff proximal portion of the guidewire that is
adequate to provide the guiding function, while providing a
sufficiently flexible distal portion to avoid damage to internal
walls of the bladder. It has been found that guidewires that are
sufficiently flexible to avoid risk of damage to internal walls of
the bladder are generally insufficiently stiff to provide adequate
guidance to the plastic sheath insertion through certain tissue
types in specific regions of the body, e.g. the supra-pubic
region.
[0049] Once the plastic sheaths 44, 45 have been inserted, the
guidewire 1 can be withdrawn. The inner sheath 45 can also be
withdrawn. At that time, the desired bladder drainage catheter 50
formed from soft, flexible plastic tubing (e.g. of approximately 4
mm outside diameter) can be introduced into the bladder via the
outer stiff plastic sheath 44. Once this action is completed, the
stiff plastic sheath 44 can be removed by tearing along its length.
In other words, the clinician may grasp the lugs 48 and strip or
peel the plastic sheath 44 away; withdrawing the distal portion
contained within the body while doing so.
[0050] In a general aspect, the plastic sheath 44 has a distal end
of inside diameter approximately equal to the outside diameter of
the guidewire, and a proximal end of inside diameter sufficient to
receive the flexible catheter, e.g. at least 4 mm.
[0051] The use of a guidewire having at least two grades of
stiffness, and preferably at least three, along its length,
facilitates the provision of several important features. Firstly,
the guidewire can be sufficiently stiff or rigid in the proximal
portion to ensure adequate guidance of the sheath which expands the
needle hole. At the same time, the flexible distal end protects the
bladder internal walls from damage.
[0052] Secondly, the graduated stiffness in the intermediate
portion provides the clinician with tactile feedback of the
positioning of the guidewire within the bladder.
[0053] It will be understood that the stiffness of the various
distal, intermediate and proximal portions need not be invariant
along the length of the respective portion.
[0054] It will be understood that, throughout the present
description, the dimensions of the various components of the
preferred embodiments are illustrative only.
[0055] Other embodiments are intentionally within the scope of the
accompanying claims.
* * * * *