U.S. patent application number 11/590422 was filed with the patent office on 2007-03-01 for drainage catheter.
Invention is credited to Anders Magnusson.
Application Number | 20070049905 11/590422 |
Document ID | / |
Family ID | 30000730 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070049905 |
Kind Code |
A1 |
Magnusson; Anders |
March 1, 2007 |
Drainage catheter
Abstract
A catheter includes a tubular body, a ring member, and at least
one elongate member. The tubular body has a distal region. The ring
member encircles at least a portion of the circumference of the
tubular member. The one elongate member has a proximal end and a
distal end, the distal end of the elongate member being coupled to
the distal region of the tubular body and the proximal end being
attached to the ring member. Forming a loop in a distal end of a
catheter includes pulling a ring that encircles at least a portion
of the circumference of the catheter. The ring is attached to a
proximal end of an elongate member, a distal end of the elongate
member is attached to a distal end of the catheter, and the
elongate member is positioned along the outside surface of the
catheter.
Inventors: |
Magnusson; Anders; (Uppsala,
SE) |
Correspondence
Address: |
FAY KAPLUN & MARCIN, LLP
15O BROADWAY, SUITE 702
NEW YORK
NY
10038
US
|
Family ID: |
30000730 |
Appl. No.: |
11/590422 |
Filed: |
October 31, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10606538 |
Jun 26, 2003 |
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11590422 |
Oct 31, 2006 |
|
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60391667 |
Jun 27, 2002 |
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Current U.S.
Class: |
604/540 |
Current CPC
Class: |
A61M 2025/0163 20130101;
A61M 25/04 20130101 |
Class at
Publication: |
604/540 |
International
Class: |
A61M 1/00 20060101
A61M001/00 |
Claims
1. A method of forming a loop in a distal end of a catheter, the
method comprising: pulling a ring encircling at least a portion of
the circumference of the catheter, wherein the ring is attached to
a proximal end of an elongate member, a distal end of the elongate
member is attached to a distal end of the catheter, and the
elongate member is at least partially positioned along the outside
surface of the catheter.
2. A method of forming a loop in a distal end of a catheter, the
method comprising: inserting an introducer into a body cavity, the
introducer comprising a hub and a sheath having a longitudinal
channel passing between a proximal end and a distal end, the hub
having a longitudinal channel and being joined to the proximal end
of the sheath, and the joined hub and sheath having a length;
inserting a catheter into the introducer, the catheter comprising a
hub, a tubular body, at least one elongate member and a ring
member, the tubular body having a distal region, the elongate
member having a length, a proximal end and a distal end, the distal
end of the elongate member being mounted to the distal region of
the tubular body and the proximal end of the elongate member being
attached to the ring member; and advancing the catheter into the
introducer until the ring member is adjacent to the introducer hub;
advancing the catheter into the introducer until the catheter hub
is adjacent to the ring member, wherein advancing the catheter into
the introducer until the catheter hub is adjacent to the ring
member causes the ring member to contact the introducer hub and
form a loop in the distal region of the tubular body.
3. The method of forming a loop of claim 2, wherein the length of
the elongate member is between approximately 1 mm and 10 mm longer
than the length of the hub and sheath.
Description
PRIORITY CLAIM
[0001] This application is a Divisional Application of U.S. patent
application Ser. No. 10/606,538 filed Jun. 26, 2003 titled
"Drainage Catheter" which claims priority to U.S. Provisional
Patent Application Ser. No. 60/391,667 filed on Jun. 27, 2002. The
entire disclosures of these prior applications are considered as
being part of the disclosure of the accompanying application and
are hereby expressly incorporated by reference herein.
TECHNICAL FIELD
[0002] The present invention relates to medical devices for
positioning in internal body cavities such as the collecting system
in the kidney, the urinary bladder, etc. In particular, the
invention relates to catheters for drainage purposes and means for
securing such catheters in place.
BACKGROUND
[0003] In many medical conditions, it is necessary to drain or
empty internal body cavities of liquids, e.g., urine, blood, etc.
For this purpose, numerous designs of catheters are available and
commonly used. If it is required that the drainage be performed
over an extended period of time, such as several days, weeks or
even months, it is essential that the catheter be properly secured
inside the body cavity that is being drained. One common type of
securable catheter is known as a Cope loop catheter or lockable
"pig-tail" catheter. This catheter is characterized by including a
means to form a curl (i.e., pig-tail) at its distal end once the
catheter has been positioned inside the body cavity, thereby
forming an efficient means to prevent or resist the catheter from
being pulled out. For example, the curl can be formed by pulling a
thread that is secured at the proximal end of the catheter and runs
inside the catheter lumen to its distal tip, where it exits through
an exit hole located in the vicinity of the catheter tip. The
thread runs back along the outer surface of the catheter, enters
the catheter again through a hole at a certain distance from the
distal exit hole, and then passes inside the catheter to the
proximal end of the catheter, where a "loose end" of the thread is
available for a physician to grip and pull. Pulling the thread
causes the two distally located holes to approach each other,
thereby forming the curl.
[0004] Percutaneous nephrostomy is one of the oldest techniques
used in interventional radiology. It comprises placing a drainage
catheter or tube inside the renal pelvis through a skin insertion.
The drainage catheter used for percutaneous nephrostomy typically
is the "Cope loop" type drainage catheter described above. Early
methods were very time consuming, requiring multiple procedural
steps. In fact, the procedure could take up to a week to complete.
However, the technique has been developed substantially and today
the entire procedure is performed at one time in one continuous
sequence of steps.
[0005] Despite the many advantages of the Cope loop catheter, in
particular its very efficient locking function by virtue of the
curl, it nevertheless still has certain disadvantages. For example,
one problem with the Cope loop catheter is the potential difficulty
in creating the desired loop, especially in an undilated system. In
particular, the catheter tip sometimes gets stuck in a calyx or in
the ureter and may require substantial manipulation before a
locking curl is obtained.
[0006] Furthermore, because urine is a supersaturated solution of
salts, the salt is easily crystallized from the solution when the
solution comes into contact with a foreign material, such as the
catheter material. If this happens, the catheter clogs and, because
the pulling thread runs inside the lumen of the catheter, the
thread may get stuck in the precipitated crystals. In this
situation, it may be very difficult, if not impossible, to
manipulate the locking thread to remove the curl and "unlock" the
catheter. As a consequence, the physician may need to perform a
more complicated and invasive intervention to remove the
catheter.
SUMMARY
[0007] In a general aspect, the present application relates to a
catheter comprising a tubular body, a ring member, and at least one
elongate member. The tubular body has a distal region. The ring
member encircles at least a portion of the circumference of the
tubular member and is slidable along the tubular member. The one
elongate member has a proximal end and a distal end, the distal end
of the elongate member being coupled to the distal region of the
tubular body and the proximal end being attached to the ring
member.
[0008] Embodiments of the catheter may include one or more of the
following features. For example, the tubular body may include an
inner lumen, an outer surface, and a pair of openings passing
between the outer surface and the inner lumen. The coupling of the
elongate member to the distal region of the tubular body may
include the elongate member passing through the pair of openings.
The elongate member may pass between the ring member and the pair
of openings along the outer surface of the tubular body.
[0009] The tubular body may include a second pair of openings
passing between the outer surface and the inner lumen and
positioned proximal to the first pair of openings. The elongate
member passes between the first pair of openings and the second
pair of openings along the outer surface and between the second
pair of openings and the ring member along at least a portion of
the inner lumen.
[0010] The tubular body may include a third pair of openings
passing between the outer surface and the inner lumen and
positioned proximal of the second pair of openings. The elongate
member passes between the third pair of openings and the ring
member along the outer surface.
[0011] The tubular body may include a loop positioned distal of the
coupling of the elongate member to the distal region of the tubular
body. The elongate member may also include a single length of a
thread passing between the distal region of the catheter and the
ring member.
[0012] The catheter can further comprise a connector piece being
attached to a proximal region of the tubular body.
[0013] The distal region of the tubular body can define at least a
first stiffness over a substantial portion thereof and a proximal
region of the tubular body can define at least a second stiffness
over a substantial portion thereof, which second stiffness is less
than the first stiffness. The tubular body can further define at
least the first stiffness from a distal end thereof to the proximal
region defining the second stiffness.
[0014] In another general aspect, a catheterization kit is
described including a catheter and an introducer. The catheter
comprises a connector piece, a tubular body, at least one elongate
member and a ring member. The tubular body has a distal region and
a proximal region and the connector piece is attached to the
proximal region of the tubular body. The elongate member has a
proximal end and a distal end, the distal end of the elongate
member being coupled to the distal region of the tubular body and
the proximal end of the elongate member being attached to the ring
member. The ring member is slidable along the tubular body. The
introducer includes a connector piece and a sheath. The sheath has
a longitudinal channel passing between a proximal end and a distal
end, and the connector piece has a longitudinal channel and is
joined to the proximal end of the sheath. The catheter connector
piece is removably attachable to the introducer connector piece
when the catheter is received within the introducer. The ring
member abuts the proximal end of the introducer when the catheter
is sufficiently positioned within the introducer, thereby causing
the elongate member to become stretched.
[0015] Embodiments of the catheterization kit may include one or
more of the following features. For example, the tubular body may
include an inner lumen, an outer surface, and a pair of openings
passing between the outer surface and the inner lumen. The coupling
of the elongate member to the distal region of the tubular body
includes the elongate member passing through the pair of openings.
The elongate member may pass between the ring member and the pair
of openings along the outer surface of the tubular body.
[0016] The tubular body may include a second pair of openings
passing between the outer surface and the inner lumen and
positioned proximal to the first pair of openings. The elongate
member passes between the first pair of openings and the second
pair of openings along the outer surface and between the second
pair of openings and the ring member along at least a portion of
the inner lumen.
[0017] The tubular body includes a third pair of openings passing
between the outer surface and the inner lumen and positioned
proximal of the second pair of openings, and the elongate member
passes between the third pair of openings and the ring member along
the outer surface.
[0018] The tubular body may include a loop positioned distal of the
coupling of the elongate member to the distal region of the tubular
body. The elongate member may be a single length of a thread
passing between the distal region of the catheter and the ring
member.
[0019] The distal region of the tubular body can define at least a
first stiffness over a substantial portion thereof and the proximal
region of the tubular body can define at least a second stiffness
over a substantial portion thereof, which second stiffness is less
than the first stiffness. The tubular body can further define at
least the first stiffness from a distal end thereof to the proximal
region defining the second stiffness.
[0020] The introducer may have a length that is approximately the
same as a length of the elongate member between the attachment of
the elongate member to the ring member and the coupling of the
elongate member to the distal region of the tubular body, and the
length may be between approximately 3 mm and 10 mm longer than the
length of the introducer.
[0021] The ring member may be securable proximally of the
introducer for stretching the elongate member. The elongate member
may be securable by a fastening means provided on the proximal end
of the introducer. The fastening means may be a clamping device.
The clamping device may be a slot in which the elongate member is
securable in a press fit.
[0022] The elongate member may extend from the point where it is
coupled to the catheter and along the outer surface of the
catheter. The fastening means may be a slit in which the elongate
member is securable by frictional engagement. The elongate member
may be coupled to the catheter at a finite distance from the distal
tip of the catheter.
[0023] The catheterization kit may further include a needle having
an inner lumen, a guide wire configured to fit within the inner
lumen of the needle, a dilator having an inner lumen configured to
pass over the guide wire and a guiding pin configured to fit within
the tubular body. The dilator may include a radiopaque section
positioned such that it is located at the distal end of the sheath
of the introducer when the dilator is sufficiently positioned
within the introducer.
[0024] In another general embodiment, a catheterization kit
includes a catheter and an introducer. The catheter includes a
tubular body, at least one elongate member and a stop. The tubular
body has a distal region, the elongate member has a length, a
proximal end and a distal end. The distal end of the elongate
member is mounted to the distal region of the tubular body, and the
proximal end of the elongate member is attached to the stop. The
stop being slidable along the tubular body. The introducer includes
a hub and a sheath. The sheath has a longitudinal channel passing
between a proximal end and a distal end. The hub has a longitudinal
channel and is joined to the proximal end of the sheath, and the
joined hub and sheath have a length. The length of the elongate
member is between approximately 3 mm and 10 mm longer than the
length of the hub and sheath. The stop abuts the proximal end of
the introducer when the catheter is sufficiently positioned within
the introducer, thereby causing the elongate member to become
stretched.
[0025] In another general aspect, forming a loop in a distal end of
a catheter includes pulling a ring that encircles at least a
portion of the circumference of the catheter. The ring is attached
to a proximal end of an elongate member, a distal end of the
elongate member is attached to a distal end of the catheter, and
the elongate member is positioned along the outside surface of the
catheter.
[0026] In another aspect, securing a catheter in a body cavity
includes inserting an introducer into a body cavity, inserting a
catheter into the introducer, advancing the catheter into the
introducer, and attaching a catheter hub to an introducer hub. The
introducer includes a hub and a sheath having a longitudinal
channel passing between a proximal end and a distal end. The hub
has a longitudinal channel and is joined to the proximal end of the
sheath. The catheter includes a hub, a tubular body, at least one
elongate member and a ring member. The tubular body has a distal
region and a proximal region, and the hub is attached to the
proximal region of the tubular body. The elongate member has a
proximal end and a distal end, and the distal end of the elongate
member is mounted to the tubular body in the distal region. The
proximal end of the elongate member is attached to the ring member,
and the elongate member passes along the outside surface of the
catheter between the ring member and the distal region of the
tubular body. The catheter is advanced into the introducer until
the catheter hub is adjacent to the introducer hub. Advancing the
catheter into the introducer causes the ring member to contact the
introducer hub and form a loop in the distal region of the tubular
body.
[0027] In another general aspect, forming a loop in a distal end of
a catheter includes inserting an introducer into a body cavity,
inserting a catheter into the introducer, advancing the catheter
into the introducer until a ring member is adjacent to an
introducer hub, and advancing the catheter into the introducer
until the catheter hub is adjacent to the ring member.
[0028] The introducer includes a hub and a sheath having a
longitudinal channel passing between a proximal end and a distal
end. The hub has a longitudinal channel and is joined to the
proximal end of the sheath. The joined hub and sheath have a
length. The catheter includes a hub, a tubular body, at least one
elongate member and a ring member. The tubular body has a distal
region, the elongate member has a length, a proximal end and a
distal end. The distal end of the elongate member is mounted to the
distal region of the tubular body and the proximal end of the
elongate member is attached to the ring member. Advancing the
catheter into the introducer until the catheter hub is adjacent to
the ring member causes the ring member to contact the introducer
hub and form a loop in the distal region of the tubular body.
[0029] The length of the elongate member is between approximately 3
mm and 10 mm longer than the length of the hub and sheath.
[0030] In another general aspect, changing drainage catheters in a
body cavity includes inserting an introducer into a body cavity,
inserting a first drainage catheter into the introducer, advancing
the first drainage catheter into the introducer, removably
connecting a catheter hub to an introducer hub and using the first
drainage catheter to drain fluids from the body cavity. The drawing
may further include disconnecting the catheter hub from the
introducer hub, withdrawing the first drainage catheter from the
introducer while leaving the introducer within the body cavity, and
inserting a second drainage catheter into the introducer.
[0031] The introducer includes the introducer hub and a sheath
having a longitudinal channel passing between a proximal end and a
distal end. The hub has a longitudinal channel and is joined to the
proximal end of the sheath. The first drainage catheter includes
the catheter hub, a tubular body, at least one elongate member and
a ring member. The tubular body has a distal region and a proximal
region. The catheter hub is attached to the proximal region of the
tubular body. The elongate member has a proximal end and a distal
end. The distal end of the elongate member is mounted to the
tubular body in the distal region, the proximal end of the elongate
member is attached to the ring member, and the elongate member
passes along the outside surface of the first drainage catheter
between the ring member and the distal region of the tubular body.
The first drainage catheter is advanced into the introducer until
the catheter hub is adjacent to the introducer hub and a loop is
formed in the body cavity by the distal region of the first
drainage catheter.
[0032] In another general aspect, drawing an internal body cavity
includes inserting an introducer into a body cavity, inserting a
first drainage catheter into the introducer, advancing the first
drainage catheter into the introducer, removably connecting a
catheter hub to an introducer hub and using the first drainage
catheter to drain fluids from the body cavity. The drawing may
further include disconnecting the catheter hub from the introducer
hub, withdrawing the first drainage catheter from the introducer
while leaving the introducer within the body cavity, and inserting
a second drainage catheter into the introducer.
[0033] The introducer includes the introducer hub and a sheath
having a longitudinal channel passing between a proximal end and a
distal end. The hub has a longitudinal channel and is joined to the
proximal end of the sheath. The first drainage catheter includes
the catheter hub, a tubular body, at least one elongate member and
a ring member. The tubular body has a distal region and a proximal
region. The catheter hub is attached to the proximal region of the
tubular body. The elongate member has a proximal end and a distal
end. The distal end of the elongate member is mounted to the
tubular body in the distal region, the proximal end of the elongate
member is attached to the ring member, and the elongate member
passes along the outside surface of the first drainage catheter
between the ring member and the distal region of the tubular body.
The first drainage catheter is advanced into the introducer until
the catheter hub is adjacent to the introducer hub and a loop is
formed in the body cavity by the distal region of the first
drainage catheter.
[0034] In another general aspect, drawing a first and a second
internal body cavity includes inserting an introducer into a body
cavity, inserting a first drainage catheter into the introducer,
advancing the first drainage catheter into the introducer,
removably connecting a catheter hub to an introducer hub, using the
first drainage catheter to drain fluids from the body cavity,
disconnecting the catheter hub from the introducer hub, withdrawing
the first drainage catheter from the introducer while leaving the
introducer within the body cavity, and inserting a second drainage
catheter into the introducer.
[0035] The introducer includes the introducer hub and a sheath
having a longitudinal channel passing between a proximal end and a
distal end. The hub has a longitudinal channel and is joined to the
proximal end of the sheath. The first drainage catheter includes
the catheter hub, a tubular body, at least one elongate member, a
ring member and a first loop positioned distal of the coupling of
the elongate member to the distal region of the tubular body. The
tubular body has a distal region and a proximal region. The
catheter hub is attached to the proximal region of the tubular
body. The elongate member has a proximal end and a distal end. The
distal end of the elongate member is mounted to the tubular body in
the distal region, the proximal end of the elongate member is
attached to the ring member, and the elongate member passes along
the outside surface of the first drainage catheter between the ring
member and the distal region of the tubular body. The first
drainage catheter is advanced into the introducer until the
catheter hub is adjacent to the introducer hub and the first loop
is positioned within the first body cavity and a second a loop is
formed in the second body cavity by a part of the distal region of
the first drainage catheter.
[0036] The catheter can provide numerous advantages. For example,
the catheter can be used to easily and simply form a loop in a body
cavity--even in those cavities in which the available space is
restricted or limited. Another advantage of the catheter is that
exchange of catheters is very easily performed. In particular, the
exchange typically will not necessitate the use of auxiliary
equipment, such as guide wires, anesthesia, and fluoroscopy.
Furthermore, the exchange of catheters can be performed by a nurse
outside a hospital, and a doctor need not supervise the
procedure.
[0037] A further advantage is that if the pulling thread is
arranged to extend along the outside of the catheter tubing, the
risk of clogging by precipitation of salt from, e.g., urine,
causing the thread to get stuck, is eliminated. This will reduce or
eliminate the problem associated with prior art Cope-loop catheters
in which the thread extends inside the catheter.
[0038] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features and advantages of the invention will be apparent
from the description, the drawings, and the claims.
DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1a is a side view of a prior art Cope-loop
catheter.
[0040] FIG. 1b is an enlarged side view of the distal tip of the
catheter of FIG. 1a illustrating a loop formed in the distal tip of
the catheter.
[0041] FIG. 2a is a side view of a set of medical devices that
includes a dilator, an introducer, a mandril, and a catheter used
for draining a body cavity.
[0042] FIG. 2b is an enlarged side view of the distal tip of the
catheter of FIG. 2a illustrating a loop formed in the distal tip of
the catheter when the thread extends to the distal tip of the
catheter.
[0043] FIG. 2c is an enlarged side view of the distal tip of the
catheter of FIG. 2a illustrating a loop formed in the distal tip of
the catheter when the thread extends to a middle region of the
catheter.
[0044] FIGS. 3a-h illustrate the procedure for using the set of
medical devices of FIG. 2a for placing the catheter of FIG. 2a in
the renal pelvis.
[0045] FIGS. 4a-d illustrate the formation of the loop that results
from the interaction between the ring and the hub of the
introducer.
[0046] FIG. 5a is a side view of a second embodiment of a drainage
catheter and introducer for draining a body cavity.
[0047] FIG. 5b is an enlarged side view of the distal tip of the
catheter of FIG. 5a.
[0048] FIG. 5c is an enlarged side view of the middle section of
the catheter of FIG. 5a illustrating a slidable ring and attached
pulling threads.
[0049] FIG. 5d is a side view of the drainage catheter of FIG. 5a
inserted into the introducer.
[0050] FIG. 5e is a side view of the drainage catheter of FIG. 5a
further inserted into the introducer such that a loop is
formed.
[0051] FIG. 6a is a side view of a drainage catheter for draining
two body cavities, wherein a loop is formed at the distal end and
the thread extends to a middle section of the catheter.
[0052] FIG. 6b is a side view of the drainage catheter of FIG. 6a
inserted into an introducer such that a loop is formed in a middle
section of the catheter.
[0053] FIG. 7 is a side view of a drainage catheter have a single
pulling thread.
[0054] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0055] FIGS. 1a and 1b illustrate a prior art Cope loop locking
catheter 2. The catheter 2 includes a tube 4 in which the drainage
liquid flows. The distal end of the tube 4 includes a plurality of
drainage openings 3 for entry into the catheter of the liquid to be
removed. The tube 4 is made of a suitable, flexible polymer
material, such as polyurethane. The proximal end of the tube 4 is
attached to a connector piece, such as a hub 6. A pulling thread 8
runs from a proximal end opening 9 of the tube 4 to which it is
fixed through the inside of a catheter lumen 10. A first portion 8a
of the thread extends to the distal end region of the tube 4 where
it penetrates the tube wall at a first point of penetration 12. A
second portion 8b of the thread extends back along the exterior of
the tube 4 to a second point of penetration 14, where it again
enters the lumen 10 of tube 4. From the second point of
penetration, a third portion 8c of the thread extends back to and
through the hub 6, where it exits at the very proximal end of the
tube 4.
[0056] The term "distal" is herein defined as far from an
introduction point of the catheter into the body, while the term
"proximal" is herein defined as nearer an introduction point of the
catheter into the body. For example, the distal end of the catheter
indicates the end of the catheter intended to be positioned within
the body, while the proximal end of the catheter indicates the end
of the catheter intended to be positioned at or near the
introduction point or outside the body. The term "distal region" is
herein used to indicate a region being intended to be positioned
inside the body far from an introduction point of the catheter,
while the term "proximal region" is herein used to indicate a
region positioned nearer the introduction point. Furthermore, the
proximal and distal end of an elongate member or a thread are
herein used to indicate the part/parts of the thread being adapted
to be positioned proximally and distally respectively, i e the
distal end of the thread can be a real end or part of the thread,
for example the middle region of the thread, being adapted to be
positioned distally.
[0057] If the physician pulls the part of the thread 8 extending
from the connector 6, the first point of penetration 12 will be
pulled in the direction of the second point of penetration 14. If
the physician continues to pull the thread 8, the distal end of the
catheter 2 will form a loop (i.e., "pig-tail") (FIG. 1b). In this
position the section 8b of the thread will have decreased its
length to virtually zero. The loop, if correctly formed inside the
cavity in which the catheter has been inserted, will provide a
reliable means to prevent the catheter from being pulled out.
[0058] The procedure for positioning the Cope loop locking catheter
2 involves penetration of the kidney, dilatation of the incision,
and thereafter inserting the catheter 2 in the dilated tissue
channel. Thus, the catheter rests in the dilated channel in direct
contact with the kidney tissue.
[0059] As indicated above, a drawback with this prior art catheter
2 is that it can be difficult to create the loop because the
catheter 2 must be inserted into the cavity to be drained to a
sufficient extent that will allow a full loop to be created. In so
doing, the catheter 2 can get stuck in various irregularities in
the cavity, such as a calyx or the ureter when the cavity is the
renal pelvis. If the catheter 2 is stuck in an irregularity, there
is insufficient space to create the loop because, for example, the
distal end will not be able to loop back on itself when the thread
8 is pulled by the physician.
[0060] Referring to FIG. 2a, a set of medical devices 20 includes a
dilator 22, an introducer 24, a pig-tail (or Cope-loop type)
catheter 26, and a guiding pin or mandril 27. The introducer 24
includes a sleeve 25a and a connector piece, such as hub 25b. As
described below in more detail, the dilator 22 is used to position
the device within a cavity to be drained. The catheter 26 has a
pulling means 28 (e.g., ring member, stop, or stopping device) that
is configured to interact with the hub 25b of the introducer 24.
The stopping device 28 may be in the form of a ring or ring member
that is slidingly attached on the catheter tubing 30. From the ring
28, an elongate member or pulling thread 32 runs to a distal point
of attachment 34 at the distal end of the catheter 26 (or to a
point near the distal end), where it penetrates the catheter tubing
30, exits on, for example, the opposite side, and runs back and
attaches to the ring 28. The pulling thread 32 penetrates the
catheter tubing 30 by simply pulling the thread through the tubing
at the tip, e.g., by means of a needle to puncture the tubing, or
by making a hole in the catheter and then pulling the thread
therethrough. The pulling thread is generally non-elastic so that
the loop can be reliably formed. Although the pulling thread 32 is
coupled to the catheter tubing 30 by passing it through a pair of
openings in the tubing, it may be coupled to the catheter by any
other suitable means, such as a metal band, an adhesive or a
knot.
[0061] The dilator 22 includes a radiopaque section 23. For
example, this section can be made of a metal having the desired
radiopacity, e.g., platinum (Pt) or gold (Au), although any method
and/or material of providing radiopacity is acceptable to provide
this function. The position of the radiopaque section 23 on the
dilator 22 is selected such that when the dilator 22 is positioned
within the introducer 24 the radiopaque section 23 is located just
at the distal end of the sleeve 25a. As described in more detail
below, the radiopaque section 23 permits a physician to ensure
under fluoroscopy that the introducer 24 is positioned within the
collecting system.
[0062] Although fluoroscopy is one method of visualizing the
introducer within the body cavity, ultrasound techniques also can
be used to visualize the placement of the medical devices (i.e.,
introducer, needle, guide wire, dilator, catheter) within the body
cavity. Ultrasound techniques for visualizing these devices within
body cavities are well-known to those of skill in the art.
[0063] The catheter 26, the introducer 24, and the dilator 22 are
fabricated from commonly used medical grade plastics using standard
techniques. For example, the plastic can be one or more of
polyurethane, polypropylene, polyethylene, nylon, polyethylene
terephthalate, polyethen, Hd-polyethen, latex, and any other
suitable polymer, as well as a Pebax.RTM. material. Furthermore,
the catheter 26 can be fabricated of more than one material.
Materials having different stiffness can be used to produce a
catheter 26 having different stiffness in different regions.
Preferably, a distal region of the catheter 26 comprising the
portion of the catheter 26 adapted to form a loop defines a
stiffness which is greater than the stiffness of a proximal region
of the catheter 26 comprising the portion of the catheter 26
adapted to be positioned within the introducer 24 when a loop is
formed. The materials having different stiffness can be welded
together or unified through melting. Alternatively, a process can
be used wherein the stiffness of the material can be regulated
during injection moulding of the catheter 26. If desired, the
catheter 26 can be produced having different thickness in different
sections. A memory metal or a spring metal can also be used in the
catheter 26.
[0064] The guiding pin or mandril 27 can be made from any medical
grade metal or polymer. The metal can be, for example, stainless
steel, nitinol, or titanium. The polymer can be one or more of the
polymers described above. The pulling thread 32 can be made from
for example nylon.
[0065] Referring to FIGS. 2b and 2c, the catheter 26 can be
configured to form a loop anywhere along the length of the tubing
30 based upon the position at which the thread 32 passes through
the tubing. For example, FIG. 2b illustrates the thread 32 passing
through the tubing 30 at a position that is at the distal end of
the catheter 26. FIG. 2c illustrates the thread 32 passing through
the tubing 30 at a position that is proximal of the distal end of
the catheter 26 by a set distance. As such, when the loop is
formed, the tubing 30 extends beyond the loop by the set distance
at which the thread passes through the catheter 26.
[0066] The set of medical devices 20 are used to place the catheter
26 in a body cavity to drain the body cavity. For example,
referring to FIGS. 3a-h, the catheter 26 can be positioned in the
renal pelvis for the purpose of draining the renal pelvis.
Initially, a hollow needle 37 is used to percutaneously puncture
the kidney 38 to provide an access path to the collecting system
39, such as the renal pelvis. The penetration is done such that the
needle enters into a calyx 39 (FIG. 3a). A guide wire 42 is then
passed through the lumen of the hollow needle 37 such that it
extends into the collecting system, which corresponds to a distance
of about 4 cm to 5 cm beyond the tip of the needle 37 (FIG. 3b).
With the guide wire 42 in position within the body cavity, the
needle then is withdrawn (FIG. 3c). The dilator 22 next is inserted
into the introducer 24, and the assembly of the dilator and the
introducer is passed over the guide wire 42 and inserted into the
kidney tissue (FIG. 3d). Passing the assembly into the tissue
widens or dilates the channel created initially by the needle 37.
To dilate the tissue in as atraumatic a manner as possible, there
should be a smooth transition between the introducer sleeve 25a and
the extension of the dilator 22 out from the introducer sleeve. For
example, the distal tip of the introducer sleeve 25a can be tapered
to have an inner diameter that is minimally larger than the outer
diameter of the dilator 22. This is most easily achieved by
tapering the distal end of the sleeve 25a to a fairly small angle,
such as less than approximately 45.degree., preferably less than
30.degree., most preferably less than 20.degree.. In general, the
smaller the angle the better, and only manufacturing techniques
limit the angle value. Of course, if the sleeve 25a is made from a
material that is thin enough, a taper may not be needed at all if
there is a very close fit of the dilator 22 within the sleeve 25a.
To decrease the friction between the introducer 24 and the dilator
22 a hydrofil friction coating may be applied on the dilator 22.
The dilator 22 may be connected to the hub 25b of the introducer 24
through a hub at the proximal end of the dilator 22. Furthermore,
the distal end of the dilator 22 is preferably formed as a sharp
edge and the inner diameter of the dilator 22 matches the diameter
of the guide wire.
[0067] The assembly of the dilator 22 and the introducer 24 then
are advanced slightly forward into the collecting system at which
point the physician optionally verifies under fluoroscopy,
ultrasound, or x-ray that the radiopaque section 23 is positioned
within the collecting system (FIG. 3e). Because the dilator 22 is
located inside the introducer 24 such that the radiopaque section
23 is located just at the distal end of the sleeve 25a, the
physician can ascertain when the sleeve 25a has been positioned
just inside the collecting system by looking for the radiopaque
section under fluoroscopy. The dilator 22 then is withdrawn, which
leaves the introducer in position within the collecting system
(FIG. 3f).
[0068] The catheter 26 is next introduced into the introducer 24
(FIG. 3g). To ease the introduction of the catheter into the
introducer, the rigid guiding pin 27 is first inserted into the
catheter to provide longitudinal rigidity and support to the
catheter. In this manner, the catheter 26 has less of a tendency to
get stuck in the introducer 24, which otherwise might occur due to
the flexibility of the catheter.
[0069] To decrease the friction between the introducer 24 and the
catheter 26 a friction reducing coating may be applied on the
catheter tubing 30. Furthermore, an O-ring is preferably placed
between the hubs 36 and 25b to make the connection leak proof.
[0070] Generally, the introducer 24 as well as the assembled
introducer-catheter subsystem has to be smooth and bend easily
without collapsing.
[0071] When the catheter 26 has been inserted into the introducer
24 to a point where the ring 28 abuts the hub 25b of the introducer
24, as shown in FIG. 3g, the thread 32 will become tight or
slightly stretched. The thread 32 is stretched because the length
of the introducer is approximately the same as the length of the
thread from the point of abutment of the ring 28 against the hub
25b and to the point of attachment of the thread at the catheter
distal end 34 where it just exits the sleeve 25a. Because the
thread 32 is stretched and cannot be elongated due to its lack of
elasticity, and because the distal point of attachment 34 cannot
move further away from the distal tip of the introducer, advancing
the catheter further into the introducer creates a loop in the
tubing 30. During the formation of the loop, the guiding pin 27
should be removed to prevent it from interfering with the loop.
Alternatively, the guiding pin 27 can be kept in place but it
should not be advanced together with the catheter 26.
[0072] As a consequence of advancing the catheter 26 further into
the introducer 24, the catheter tubing 30 behind the point 34 will
therefore begin to be expelled out from the introducer and extend
past the point 34, whereby the loop will start to form (FIG. 3h).
The physician advances the catheter 26 until the hub 36 of the
catheter mates with the corresponding hub 25b of the introducer. At
this position the hubs 36 and 25b, respectively, can be coupled
together, e.g., by a thread engagement, a bayonet type lock or by
any other suitable locking means. In this manner, the catheter is
locked into position within the collecting system (i.e., renal
pelvis) with the loop effectively anchoring the catheter within the
kidney. The procedure of placing the catheter 26 can be summarized
as follows: (1) use a needle to create a channel through tissue to
the cavity to be drained; (2) insert a guide wire through the
needle and advance the guide wire into the cavity; (3) remove the
needle and pass a dilator and an introducer over the guide wire and
dilate the tissue; (4) remove the dilator and pass a catheter
having a pulling thread attached at its distal end over the guide
wire and into the catheter; (5) stop the insertion of the catheter
when the point of thread attachment is located just beyond the
distal catheter opening; (6) ascertain that the thread is stretched
and that it is secured in a stretched position; (7) advance the
catheter further into the introducer to begin to form a loop at the
distal catheter opening; (8) couple the catheter and introducer to
each other after a loop of a desired size has been formed; and,
optionally, (9) secure the introducer/catheter assembly to the
patient's skin.
[0073] In general, steps (5) and (6) are automatically performed by
virtue of the pulling thread 32 being attached to the ring 28,
which functions as a stopping means when it abuts the hub 25b of
the introducer. The desired size of the loop also is automatically
obtained by adapting the length of the catheter such that the
desired loop size is formed when the catheter hub 36 just abuts the
introducer hub 25b, or when the two hubs have been properly coupled
to each other, e.g., by threading or by a bayonet type lock or the
like.
[0074] More broadly the procedure of placing the catheter 26 can be
performed by: (1) dilating the tissue surrounding the body cavity
to form a channel therein; (2) positioning an introducer tube in
the channel; (3) inserting a catheter having a pulling thread
attached at its distal end into the introducer; (4) ascertaining
that the pulling thread is stretched and that it is secured in a
stretched position when the point of thread attachment is located
just beyond the catheter exit opening; (5) advancing the catheter
further into the introducer to thereby form a loop at the distal
catheter opening; and (6) locking the catheter in the position when
a loop of a desired size has been formed.
[0075] FIGS. 4a-d illustrate the interaction between the catheter
26 and the introducer 24 that is a key to forming the loop.
Initially, the catheter 26 is advanced within the introducer 24
until the ring 28 rests against the connector 25b (FIG. 4a). At
this point, the distal tip of the catheter extends slightly out of
the introducer and the pulling thread is tight. The distance
between the connector 25b and the connector 36 is d.sub.1, which is
specified to be approximately the circumference of the loop to be
formed. Moreover, as the catheter is advanced the combination of
the catheter extending beyond the introducer and the distance
between the two connector pieces 25b, 36 will be approximately
d1.
[0076] The physician then advances the catheter 26 slightly further
into the introducer 24. Because the ring 28 is resting against the
connector 25b and because the pulling thread 32 is already tight,
further advancing the catheter 26 causes the start of the loop to
be formed (FIG. 4b). As the catheter is advanced, the distance
d.sub.1 is reduced to a distance d.sub.2. As described above, the
reduction in distance d.sub.1 is approximately the same as the
amount by which the catheter extends beyond the introducer. As the
catheter 26 is further advanced within the introducer 24, the
pulling thread 32 remains a generally constant length, which keeps
the distal end of the catheter adjacent to the distal tip of the
introducer. Thus, the catheter tubing 30 begins to form a larger
loop as it is advanced though the introducer (FIG. 4c). As the
distance d.sub.2 is reduced to a distance d.sub.3, an approximately
equal amount is advanced through the introducer. Finally,
completely advancing the catheter 26 into the introducer 24 traps
the ring 28 between the connector pieces 25b, 36 and reduces the
distance d.sub.3 to d.sub.4 (FIG. 4d). The circumference of the
loop when the ring 28 is trapped between the connector pieces 25b,
36 is approximately d.sub.1. The circumference of the loop can be
set by increasing or decreasing the length of the pulling thread
32. For example, to increase the circumference of the loop, the
length of the pulling thread should be reduced and to decrease the
circumference of the loop, the length of the pulling thread should
be increased.
[0077] In general, the introducer 24 has a length that is
approximately the same as a length of the elongate member or
pulling thread 32 that passes between the attachment of the
elongate member to the pulling means or ring and the coupling of
the elongate member to the distal region of the tubular body. More
particularly, the length of the elongate member or pulling thread
32 that passes between the attachment of the elongate member to the
pulling means or ring and the coupling of the elongate member to
the distal region of the tubular body is between approximately 3 mm
and 10 mm longer than the length of the introducer.
[0078] An advantage of the medical devices 20 described herein is
that the catheter 26 can be easily changed if, for example, the
catheter becomes clogged. In fact, the catheter 26 can be changed
by a nurse without any auxiliary means and equipment, such as
anesthesia. In particular, the catheter 26 is changed out as
follows. Initially, the nurse or physician simply releases the lock
between the introducer 24 and the catheter 26 and withdraws the
catheter from the introducer. Withdrawing the catheter 26 causes
the loop to automatically begin to reduce its size. Withdrawing the
catheter 26 until it does not extend beyond the introducer
completely eliminates the loop. Because the pulling thread 32 runs
along the outside of the catheter 26 in the space between the
introducer's inner wall and the catheter's outer surface, it is
unlikely that any salts will precipitate enough to fix the thread
to the catheter or introducer. Precipitation of salts causing
fixation of the thread to the catheter is the most common problem
with prior art catheters because the thread runs almost entirely
inside the catheter.
[0079] When the catheter 26 has been removed, a new catheter 26 is
provided, the guiding pin 27 is inserted into the catheter lumen to
render the catheter stiff enough for adequate pushability, and the
catheter then is reinserted. The guiding pin 27 then is removed or
retracted, and the catheter 26 is advanced into the introducer 24
such that the loop begins to form at the distal tip of the
catheter.
[0080] Although the medical devices 20 will function very well as
described above, modifications can be made that also will function
very well. For example, the thread 32 does not necessarily need to
be secured to the ring 28. Instead, the thread 32 can be provided
as a single thread, attached at the distal end of the catheter
tubing 30, but not secured at its proximal end. Instead of securing
the proximal end to the ring, the thread should be securable to,
for example, the connector pieces 25b and/or 36. In such an
implementation, there should be some indicator mark on the thread
that identifies when the distal point of attachment of the thread
is located as desired, namely, just beyond the distal exit opening
of the catheter tube. This identification can be achieved by a
simple color mark positioned on the thread, or on the tube, such
that the marking will reach the proximal insertion opening in the
introducer hub or connector piece 25b exactly when the distal point
of attachment of the thread to the tubing 30 has reached its
desired position. At this point, the physician or nurse secures the
loose thread end on the introducer hub 25b by any suitable means,
such as, for example, a clamp provided on the connector or
inserting the thread into a very narrow slit in the connector into
which the thread can be forced to fit in a frictional engagement by
virtue of its diameter being larger than the width of the slit.
Many other securing means will work as long as they provide secure
fixation of the thread to the hub 25b.
[0081] Referring to FIGS. 5a-c, in a further implementation, a
drainage catheter 40 that is configured to be used with the
introducer 24 includes a connector 45 and tubing 50. The tubing 50
includes openings 55 at a distal end 60 of the catheter 40 for
draining fluid. The tubing 50 also includes a first set of openings
65 at the distal end 60 of the catheter, a second set of openings
70 that are proximal to the first set of openings 65, and a third
set of openings 75 that are proximal to the second set of openings
70. The drainage catheter 40 also includes a stop member or ring 80
that is slidably mounted to the tubing 50.
[0082] The drainage catheter 40 differs from the drainage catheter
26 in part because a pulling thread 85 passes from outside of the
catheter to the inside of the catheter and then back to the outside
of the catheter. Specifically, the pulling thread 85 has two ends
90, 95, both of which are attached to the ring 80, for example,
using a knot, adhesive, or other attaching means. The pulling
thread 85 passes from the ring 80 into the third set of openings 75
and passes inside the inner lumen of the catheter 40. The pulling
thread 85 passes out of the lumen of the catheter through the
second set of openings 70. The pulling thread 85 then runs along
the outside of the catheter 40 until it reaches the first set of
openings 65, at which point the thread passes through the first set
of openings into the lumen of the catheter. The distance between
the first set of openings 65 and the second set of openings 70 is
approximately the circumference of the loop that is formed when the
catheter 40 is inserted into the introducer 24. The distance
between the third set of openings 75 and the connector 45 is
approximately the same as the distance between the first set of
openings 65 and the second set of openings 70. By passing the
pulling thread 85 into the second set of openings 70, the pulling
thread will not rub against the distal end of the introducer when
the catheter 40 and introducer 24 are positioned within the body
cavity. This is advantageous because it extends the life of the
thread and limits that mode of failure as a reason for replacing
the catheter.
[0083] Referring to FIG. 5d, in use, the catheter 40 is advanced
into the introducer 24, which is already positioned within a body
cavity, until the connector 25b contacts the ring 80, at which
point the pulling thread 85 becomes taut. Further advancing the
catheter 40 into the introducer 24 causes the connector 25b to push
the ring 80 along the catheter tube 50 in the direction of the
connector 45.
[0084] Referring to FIG. 5e, completely advancing the catheter 40
into the introducer 24 until the connector 25b, ring 80, and
connector 45 are compressed together causes a loop 97 to form at
the distal end 60 of the catheter 40. The second set of openings 70
are positioned along the length of the catheter tube 50 at a
distance from the distal end such that the distal end of the
introducer is proximal to the openings 70 when the catheter 40 is
completely advanced into the introducer 24. In this manner, the
pulling thread 85 is not likely to be rubbed by the distal end of
the introducer 24 over the extended period in which the catheter 40
and introducer 24 are left within the body cavity. Continuous or
regular rubbing of the distal end of the introducer 24 against the
pulling thread 85 may damage the pulling thread and cause it to
break.
[0085] Although FIG. 5a illustrates a particular distance between
the second pair of openings 70 and the third pair of openings 75,
the distance can be increased or decreased. For example, the
distance can be set at approximately one centimeter by placing the
third pair of openings closer to the distal end 60 such that the
pulling thread is within the inner lumen of the catheter 40 for
only that one centimeter. This advantageously reduces the length of
pulling thread that can have salts deposited upon it, which, as
described above, can cause the pulling thread to be fixed in place
against the inner lumen of the catheter. Even if only one
centimeter of pulling thread is fixed against the inner lumen, it
is likely that the physician will be able to easily loosen that
fixation and remove the loop in the catheter so that the physician
can easily withdraw the catheter from the introducer.
[0086] Referring to FIGS. 6a and 6b, in a further implementation, a
drainage catheter 100 that can drain two body cavities is
configured to be used with the introducer 24 and includes a
connector 105 and tubing 110. The tubing 110 includes a first set
of openings 115 at a distal end 120 for draining fluid in a first
body cavity and a second set of openings 125 at a middle section
130 for draining fluid in a second body cavity. The first set of
openings 115 are formed within a first loop 135 and the second set
of openings 125 are formed within a second loop 140. The first loop
135 is formed in the tubing 110 using standard methods, e.g.,
placing the catheter 100 over a curved mandril and placing the
assembly in a heat oven to impart the curve in the mandril to the
catheter. The catheter 100 also includes a ring 145, a pulling
thread 150, and openings 155 through which the pulling thread
passes. Advancing the catheter 100 into the introducer 24 causes
the ring 145 to slidingly move along the tubing 110 and form the
loop 140. The catheter 100 also may include a radiopaque band 160
mounted to the first loop 135 such that the placement of the
catheter 100 can be viewed under fluoroscopy to ensure that the
first loop is correctly positioned within the first body cavity to
be drained.
[0087] The catheter 100 is used, for example, to drain the kidney
and the bladder. The catheter 100 is inserted in a manner similar
to the drainage catheters described above. Initially, however, the
first loop 135 is straightened to pass through the introducer 24.
Optionally, the catheter 100 can be placed over a guide wire. In
either case, the catheter 100 is advanced until the first loop 135
is within the bladder. In so doing, the introducer connector 25b
pushes the ring 145 and forms the second loop 140 within the
kidney.
[0088] In a further implementation, it is not necessary that the
pulling thread be fixed or secured near the distal tip of the
catheter. If it is desirable to drain the kidney (collecting
system) at a point further down in the kidney, e.g., closer to the
ureter, it is necessary to provide a relatively long tip that
reaches as much as up to approximately 10 cm beyond the point of
entry into the collecting system. Nonetheless, it is advantageous
to position the loop at that entry point into the collecting system
to provide a reliable fixation. The point of fixation of the thread
on the catheter is located just beyond the distal opening of the
introducer tube.
[0089] A number of embodiments of the locking loop catheter have
been described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, referring to FIG. 7, the
thread 32 that extends along both sides of the tubing 30 can be
configured to extend along only one side of the tubing by attaching
one end of the thread to the distal tip end 34 and the other end to
the stopping device or ring 28. This would, however, require an
attachment means 170 at the tip, e.g., by a knot, by gluing, metal
band, or molding, etc., to ensure that the end of the thread is
securely attached to the tubing. The metal band can be a radiopaque
metal band such that it is visible under fluoroscopy. The pulling
thread, although shown running along the outside of the catheter,
can be configured to run both inside and outside the catheter in
the manner described above with respect to the drainage catheter 40
of FIG. 5a. Similarly, although the catheters have been described
with reference to application in catheterization of the renal
pelvis, it is to be understood that the catheter have broader
application than use only in the renal pelvis. For example, the
catheters will function equally well for draining other body
cavities of a human or an animal, such as but not limited to the
urinary bladder, the gall bladder, abscesses, peritoneal and
thoracic cavity. Accordingly, other embodiments are within the
scope of the following claims.
* * * * *