U.S. patent application number 09/853511 was filed with the patent office on 2002-02-28 for hemodialysis catheter.
This patent application is currently assigned to Radius International Limited Partnership. Invention is credited to Quinn, David G..
Application Number | 20020026156 09/853511 |
Document ID | / |
Family ID | 26951946 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020026156 |
Kind Code |
A1 |
Quinn, David G. |
February 28, 2002 |
Hemodialysis catheter
Abstract
A hemodialysis catheter comprising a dual lumen tube with a
bullet nose bolus at its distal end. A venous port is formed in one
side of the bolus adjacent the bullet nose of the bolus. An
arterial port is formed in the bolus circumferentially displaced
180.degree. around the catheter from the venous port. The bolus
contains a venous passage which transitions from a smaller diameter
D-shaped cross-section to a larger diameter circular cross-section.
The bullet nose is thinner than the tube but is inclined on an
angle to the axis of the tube so that a portion of its outer
periphery is substantially tangent to a hypothetical cylinder
containing the trailing edge of the venous port.
Inventors: |
Quinn, David G.; (Grayslake,
IL) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
Radius International Limited
Partnership
|
Family ID: |
26951946 |
Appl. No.: |
09/853511 |
Filed: |
May 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09853511 |
May 11, 2001 |
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09651455 |
Aug 30, 2000 |
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09853511 |
May 11, 2001 |
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09651763 |
Aug 30, 2000 |
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09853511 |
May 11, 2001 |
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PCT/US00/3200 |
Nov 21, 2000 |
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09853511 |
May 11, 2001 |
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09759582 |
Jan 11, 2001 |
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60266617 |
Feb 6, 2001 |
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Current U.S.
Class: |
604/264 |
Current CPC
Class: |
A61M 25/007 20130101;
A61M 2025/0081 20130101; A61M 25/0023 20130101; A61M 25/003
20130101; A61M 25/008 20130101; A61M 1/85 20210501; A61M 25/0068
20130101; A61M 2025/0037 20130101; A61M 25/0069 20130101; A61M
2025/0031 20130101 |
Class at
Publication: |
604/264 |
International
Class: |
A61M 003/00; A61M
005/00; A61M 025/00 |
Claims
1. A bolus for a hemodialysis catheter, comprising: a) a general
cylindrical body molded of resilient plastic and including a rear
connector section, a front nose section and an intermediate passage
section; b) said passage section containing first and second
axially extending passages having a septum therebetween, said first
passage communicating with a first port opening radially out of
said cylindrical body in said passage section, said second passage
communicated with a second port opening radially out of said
cylindrical body in said passage section; c) said nose section
having a bullet nose and joining said passage section immediately
at the front end of said second port and; d) the thickness of said
nose section where it joins said passage section at the front end
of said second port being substantially less than the diameter of
said passage section behind said second port.
2. The bolus of claim 1 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said second port.
3. The bolus of claim 1 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said first port.
4. The bolus of claim 1 further characterized in that: a) said
first passage has a substantially uniform cross-sectional area
along substantially its entire length; and b) said second passage
has one cross-sectional area adjacent said connector section and
another cross-sectional area where it communicates with said second
port, said other cross-sectional area being greater than said one
cross-sectional area.
5. The bolus of claim 1 further characterized in that: a) said nose
section is offset to one side of the longitudinal axis of said
bolus in the direction of said second port so that a portion of the
outer periphery of said bullet nose section normally is
substantially tangent to an imaginary cylinder containing the outer
surface of said passage section immediately behind said second
port.
6. The bolus of claim 1 further characterized in that: a) said nose
section is approximately elliptical in cross-section where it joins
said passage section.
7. The bolus of claim 1 further characterized in that: a) said
bolus has side surfaces which, approximately at the mid-point of
said second port, begin converging toward the axis of said
bolus.
8. The bolus of claim 1 further characterized in that: a) said
second passage has a substantially circular cross-section where it
communicates with said second port; and b) said second port extends
circumferentially around more than 180.degree. of the circumference
of said second passage.
9. The bolus of claim 1 further characterized in that: a) said
second port has a trailing edge, the portion of said passage
section in front of said trailing edge being inclined to the
longitudinal axis of said bolus.
10. A bolus for a hemodialysis catheter, comprising: a) a general
cylindrical body molded of resilient plastic and including a rear
connector section, a front nose section and an intermediate passage
section arranged in axially aligned relationship; b) said
intermediate passage section containing first and second axially
extending passages having a septum therebetween, said first passage
communicating with a first port opening radially out of said
cylindrical body in said passage section, said second passage
communicated with a second port opening radially out of said
cylindrical body in said passage section; c) each of said ports
having a trailing edge extending around a portion of the
circumference of said bolus body; d) said front nose section having
a rounded bullet nose; e) said second passage having one
cross-sectional area adjacent said connector section and another
cross-sectional area where it communicates with said second port,
said other cross-sectional area being greater than said one
cross-sectional area.
11. The bolus of claim 10 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said second port.
12. The bolus of claim 10 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said first port.
13. The bolus of claim 10 further characterized in that: a) said
front nose section begins at the front end of said second port and
has a maximum thickness at that point which is less than the
outside diameter of said passage section at said trailing edge of
said second port.
14. The bolus of claim 13 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said second port.
15. The bolus of claim 13 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said first port.
16. The bolus of claim 10 further characterized in that: a) said
nose section has a center which is offset to one side of the
longitudinal axis of said bolus in the direction of said second
port so that a portion of the outer periphery of said bullet nose
section normally is substantially tangent to an imaginary cylinder
containing the outer surface of said passage section.
17. The bolus of claim 10 further characterized in that: a) said
nose section is elliptical in cross-sectional configuration where
it joins said passage section.
18. The bolus of claim 10 further characterized in that: a) said
bolus body has converging side walls from about the mid-point of
said second port forwardly.
19. The bolus of claim 10 further characterized in that: a) first
port extends around less than 180.degree. of the circumference of
said bolus body; and b) said second port extends around more than
180.degree. of the circumference of said second passage where it
communicates with said second port.
20. The bolus of claim 10 further characterized in that: a) each of
said trailing edges is approximately semi-circular in cross-section
along its entire length.
21. A bolus for a hemodialysis catheter, comprising: a) a general
cylindrical body molded of resilient plastic and including a rear
connector section, a front nose section and an intermediate passage
section arranged in axially aligned relationship; b) said
intermediate passage section containing first and second axially
extending passages having a septum therebetween, said first passage
communicating with a first port opening radially out of said
cylindrical body in said passage section, said second passage
communicated with a second port opening radially out of said
cylindrical body in said passage section; c) each of said ports
having a trailing edge extending around a portion of the
circumference of said bolus body; d) said front nose section having
a maximum thickness which is less than the diameter of the trailing
portion of the bolus and having a rounded bullet nose; e) said
front nose section also having a longitudinal axis which is
inclined to the longitudinal axis of said bolus in the direction of
said second port so that a portion of the outer periphery of said
bullet nose section is normally substantially tangent to an
imaginary cylinder containing the outer surface of said passage
section at said trailing edge of said second port even though its
maximum thickness is less than the diameter of the trailing portion
of the bolus.
22. The bolus of claim 21 further characterized in that: a) said
front nose section beginning at the front end of said second port
and having a cross-section at that point which are less than the
cross-sectional of said passage section.
23. The bolus of claim 21 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said second port.
24. The bolus of claim 21 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said first port.
25. The bolus of claim 21 further characterized in that: a) said
first passage has a substantially uniform crosssectional area along
substantially its entire length; and b) said second passage has one
cross-sectional area adjacent said connector section and another
cross-sectional area where it communicates with said second port,
said other cross-sectional area being greater than said one
cross-sectional area.
26. The bolus of claim 21 further characterized in that: a) said
bullet nose section is elliptical in cross-sectional configuration
where it joins said passage section.
27. The bolus of claim 21 further characterized in that: a) said
bolus body narrows in plan configuration from the mid-point of said
second port forwardly.
28. The bolus of claim 21 further characterized in that: a) said
first port extends around less than 180.degree. of the
circumference of said bolus body; and b) said second port extends
around more than 200.degree. of the circumference of said second
passage.
29. The bolus of claim 21 further characterized in that: a) each of
said trailing edges is approximately semi-circular in cross-section
along its entire length.
30. A hemodialysis catheter including a dual lumen tube and a bolus
on a distal end of said tube, said bolus comprising: a) a bolus
body molded of plastic in a generally cylindrical shape about a
longitudinal axis, said bolus body having first and second axially
extending passages therein, said first passage terminating in a
radially extending first port and said second passage terminating
in a radially extending second port; b) said radially extending
first and second ports being angularly displaced from each other
around the axis of said bolus body; c) said bolus body including a
nose section forming a rounded front end on said bolus, the center
of said nose section being radially offset from the axis of the
bolus itself in the angular direction of said second port.
31. The bolus of claim 30 further characterized in that: a) said
second passage includes a passage portion having a D-shape
cross-section and a passage portion having a cross-section of
another shape; b) said passage portion with a cross-section of said
other shape having a larger cross-section than said D-shape
cross-section portion.
32. The bolus of claim 31 further characterized in that: a) said
cross section of said other shape being circular.
33. The bolus of claim 31 further characterized in that: a) said
bolus body has an axially elongated stiffening arch formed in its
outer surface opposite said second port.
34. The bolus of claim 33 further characterized in that: a) said
bolus body has an axially elongated stiffening arch formed in its
outer surface opposite said first port.
35. The bolus of claim 33 further characterized in that: a) said
stiffening arch extends radially inwardly from an outermost end
adjacent said first port to an innermost end adjacent said nose
section.
36. The bolus of claim 30 further characterized in that: a) said
first and second ports being angularly displaced from each other by
about 180.degree..
37. A hemodialysis catheter including a dual fumen tube and a bolus
on a distal end of said tube, said catheter comprising: a) a tube
body containing first and second lumens; and b) a bolus body molded
of resilient plastic in a generally cylindrical shape about a
longitudinal axis; c) said bolus body having first and second
axially extending passages therein; said first passage terminating
in a radially extending first port in the side of said body and
said second passage terminating in a radially extending second port
in the side of said body; d) said radially extending first and
second ports being angularly displaced from each other
approximately 180.degree. around the axis of said bolus body; e)
said first port extending circumferentially around said bolus body
for less than 180.degree.; f) said second port extending
circumferentially around said bolus body for less than 180.degree.
but extending circumferentially around said second passage section
where it communicates with said second port for more than
200.degree.; g) said bolus body including a nose section forming a
rounded front end on said bolus in front of said second port.
38. The catheter of claim 37 further characterized in that: a) said
nose section is, at its largest cross-section, substantially
smaller in cross-section than the rest of said bolus body.
39. The catheter of claim 38 further characterized in that: a) the
longitudinally axis of said nose section is inclined to the
longitudinal axis of the bolus itself whereby said nose section is
directly in front of said second port.
40. The catheter of claim 39 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said second port.
41. The catheter of claim 39 further characterized in that: a) said
bolus body includes an axially extending stiffening arch formed in
its outer periphery opposite said first port.
42. The catheter of claim 39 further characterized in that: a) said
first passage has a substantially uniform cross-sectional area
along substantially its entire length; and b) said second passage
has one cross-sectional area adjacent said connector section and
another cross-sectional area where it communicates with said second
port, said other cross-sectional area being greater than said one
cross-sectional area.
43. The catheter of claim 39 further characterized in that: a) said
second passage includes a passage portion having a D-shape
cross-section and a passage portion having a cross-section of
another shape; b) said passage portion with a cross-section of said
other shape having a larger cross-section than said D-shape
cross-section portion.
44. The bolus of claim 33 further characterized in that: a) said
cross-section of said other shape is circular.
45. The bolus of claim 34 further characterized in that: a) said
bolus body has an axially elongated stiffening arch formed in its
outer surface opposite said second port.
46. The bolus of claim 35 further characterized in that: a) said
bolus body has an axially elongated stiffening arch formed in its
outer surface opposite said first port.
47. The bolus of claim 36 further characterized in that: a) said
stiffening arch curves radially inwardly relative to the
longitudinal axis of the bolus from an outermost end adjacent said
first port to an innermost end adjacent said nose section.
48. A hemodialysis catheter comprising: a). a tube containing a
first substantially D-shape lumen and a second substantially
D-shape lumen, said tube having a distal end through which said
lumens open; b) an axially elongated bolus having a connector
section connected to said distal end of said tube, a passage
section containing a first axially extending passage and a second
axially extending passage and a nose section; c) said nose section
having a rounded nose which is unperforated axially of the bolus;
d) said passage section also containing a first radially extending
port communicating with said first passage and a second radially
extending port communicating with said second passage; e) said nose
section beginning immediately adjacent the front end of said second
port; f) said nose section having a maximum thickness which is at
least 20% less than the outside diameter of said tube; g) said
second passage including a D-shape cross-section portion adjacent
said connector section and a substantially circular cross-section
portion adjacent said second port; h) said radially extending ports
being disposed on different radials from the longitudinal axis of
said bolus.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 09/651,455 filed Aug. 30, 2000, U.S.
application Ser. No. 09/651,763 filed Aug. 30, 2000, PCT
application Ser. No. PCT/US00/3200 filed Nov. 21, 2000, U.S.
application Ser. No. 09/759,582, filed Jan. 11, 2001, and U.S.
provisional application Ser. No. 60/266,617, filed Feb. 6,
2001.
FIELD OF THE INVENTION
[0002] This invention relates in general to hemodialysis. It
relates, more particularly, to hemodialysis catheters.
BACKGROUND OF THE INVENTION
[0003] Hemodialysis, as practiced today, normally employs one of
two types of catheter to remove blood from the patient for
processing and return processed blood to the patient. Most
commonly, a catheter tube containing two lumens is used, each lumen
having a generally semi-cylindrical or D-shape configuration. This
type of catheter is frequently referred to as a dual lumen
catheter. Alternatively, two tubes, each with a full cylindrical
configuration, are used separately to remove blood for dialysis and
return the processed blood.
[0004] Flow rates possible with conventional dual lumen catheters
are usually lower than those achievable where separate tubes are
used to remove blood from a vein for dialysis and then return
processed blood back to the vein. Thus, the use of two tubes has
become more and more popular as the capacity (maximum flow rate) of
hemodialysis membranes has increased.
[0005] Hemodialysis membranes are now able to process blood at over
500 ml of flow per minute. Even higher processing rates are
foreseeable. However, problems occur with both the line introducing
purified blood back into the vein (the venous or outflow line) and
the line removing blood for purification (the arterial or intake
line) at flow rates above 300 ml per minute. A high flow rate from
the venous line may cause whipping or "firehosing" of the tip in
the vein with consequent damage to the vein lining. A corresponding
high flow rate into the arterial line may cause the port to be
sucked into the vein wall, resulting in occlusion. It should be
understood, of course, that both lines normally access the superior
vena cava and the designations are used for differentiation
purposes.
[0006] Speed of flow through a catheter lumen, whether it be in a
single lumen or a dual lumen catheter, is controlled by a number of
factors including the smoothness of the wall surface, the internal
diameter or cross-sectional area of the tube lumen, and the length
of the tube lumen. The most important factor is the cross-sectional
area of the tube lumen. The force or speed of the fluid flow in a
tube lumen for a given cross-sectional area is controlled by the
external pumping force, of course. This is a positive pressure
pushing processed blood through the venous lumen and a negative
(suction) pressure pulling unprocessed blood through the arterial
lumen.
[0007] Problems encountered in providing for a high flow rate
through a catheter are magnified in a dual lumen catheter
construction. Because each of the lumens in a dual lumen catheter
normally has a D-shape, it has been assumed that flow rates are
limited. Furthermore, such dual lumen catheters are, to a great
extent, catheters with a main port which opens at the end of a
lumen substantially on the axis of the lumen. Thus, "firehosing"
frequently results. Fire-hosing may damage the vein wall,
triggering the build-up of fibrin on the catheter tip. Fibrin
build-up may result in port occlusion.
[0008] There are dual lumen catheters which utilize side ports for
both outflow and inflow. An example is the catheter disclosed in
the Cruz et al. U.S. Pat. No. 5,571,093. However, such catheters
have not been entirely successful in solving problems related to
hemodialysis with dual lumen catheters, e.g., high incidences of
catheter port occlusion as well as some degree of fire-hosing.
[0009] Catheters of almost all types are also pliable so that they
do not damage body tissue when they are in-situ. Pliability can
create a problem during insertion, however, because the catheters
can kink when they meet resistance. Thus, there is often a need for
a certain amount of stiffness so that the catheters can be directed
within body vessels or cavities. There are currently two methods of
providing this stiffness; stylets and guide wires.
[0010] A stylet can be a single or a twisted wire with a blunt end
that is inserted into the catheter to make it stiff. The stylet is
often used with bullet nose catheters and maintains its position
within the catheter as the catheter is inserted. The stiffened
catheter is advanced into the blood vessel with the stylet.
[0011] In contrast, guide wires are used to both stiffen the
catheter and to provide a guide for the insertion. Commonly, the
guide wire is inserted into the blood vessel before the catheter.
The catheter is then inserted into the blood vessel over the wire,
and follows the wire as it travels inside the vessel. Guide wires
are most often utilized with catheters that are inserted deep into
the body, such as with central venous catheters that are inserted
into the heart. The thin guide wire more easily makes the bends and
turns necessary for this type of placement.
[0012] In guide wire insertion where the catheter must be inserted
over the guide wire, catheters with open ends are normally utilized
to permit passage of the guide wire. These catheters are more
likely to cause damage to body tissue during insertion than bullet
nose catheters, for example, because of their flat ends and side
edges. Open ended catheters are also more likely to damage tissue
than bullet nose catheters while in-situ. Nevertheless, the need
for deep catheter insertion has heretofore made guide wire
insertion of open-ended catheters the accepted procedure in spite
of the disadvantage of their flat or blunt end design.
[0013] As an alternative, bullet nose catheters have occasionally
been used with guide wires in some applications by incorporating a
small hole through the nose for the wire to pass through. This
approach has generally been found undesirable, however, because the
hole in the bullet nose can later collect particulate matter and be
a focal point for infection.
SUMMARY OF THE INVENTION
[0014] An object of the invention is to provide an improved dual
lumen hemodialysis catheter.
[0015] Another object is to provide a dual lumen hemodialysis
catheter which accommodates flow rates substantially as high as the
latest separate lumen catheters.
[0016] Still another object is to provide a dual lumen hemodialysis
catheter which is capable of returning processed blood to the
patient at high flow rates without harmful firehosing of the
catheter tip.
[0017] Yet another object is to provide a dual lumen hemodialysis
catheter which permits high flow rates while minimizing trauma and
potential red cell damage so as to substantially avoid
clotting.
[0018] A further object is to provide a dual lumen hemodialysis
catheter which substantially reduces the incidence of port
occlusion.
[0019] Still a further object is to provide a dual lumen
hemodialysis catheter in which occlusion of the return line port is
substantially avoided regardless of the flow rate.
[0020] Still a further object is to provide a dual lumen
hemodialysis catheter which facilitates reversal of the venous and
arterial lines to relieve port occlusion without increasing the
potential for mixing of dialyzed blood with blood being removed for
dialysis
[0021] Another object of the invention is to provide an improved
bullet nose bolus for use on catheters ranging in size from 3
French to 22 French in any medical application.
[0022] A further object is to provide a bullet nose bolus that
protects the leading edge of the catheter outflow or inflow port
from rubbing against the vessel wall.
[0023] Another object is to provide a bullet nose bolus for a
catheter that will not kink during insertion.
[0024] Another object of the present invention is to provide an
improved catheter for use with a guidewire.
[0025] Still another object is to provide a bullet nose bolus for a
catheter which is compatible with a guide wire yet does not require
an axially extending hole through the nose.
[0026] Another object is to provide a bullet nose bolus for a
catheter that can be inserted simultaneously with a guide wire
through a flexible introducer sheath that is essentially the same
size as the catheter itself.
[0027] Another object is to provide a bullet nose bulus for a
catheter that follows a guide wire through bends in a patient's
vein and turns without causing increased resistance to passage
through the vein.
[0028] Another object is to provide a bullet nose bolus that always
presents a rounded surface to the vein wall, even when the catheter
is following a guide wire around a bend.
[0029] Another object is to provide a bolus with a nose which is
designed to flex away from the guide wire in only one
direction.
[0030] The foregoing and other objects are realized in accord with
the present invention by providing a dual lumen hemodialysis
catheter including a bulletnose bolus having a radially opening
outflow or venous port and a radially opening intake or arterial
port The arterial port is circumferentially displaced 180.degree.
around the bolus from the venous port.
[0031] The venous port opens radially through the bolus immediately
behind its bullet nose. The D-shape venous lumen in the catheter
tube communicates with a corresponding D-shape venous passage in
the body of the bolus. That D-shape venous passage transitions into
a circular cross-section venous passage before reaching the venous
port, while increasing in cross-sectional area from the D-shape
passage to the circular passage.
[0032] The arterial port is axially displaced from the venous port
and opens radially through the bolus immediately behind the venous
port, albeit 180.degree. displaced therefrom. The arterial port
communicates directly with a corresponding D-shape arterial passage
in the body of the bolus.
[0033] In front of the arterial port and opposite the venous port,
the profile of the bolus curves in an arc toward the side of the
bolus in which the venous port is disposed, creating a stiffening
arch in the passage section opposite the venous port. From the
trailing edge of the venous port forward, the passage section and
the nose section are effectively inclined to the longitudinal axis
of the bolus and tube, and toward the venous port side of the
bolus. The bullet nose of the nose section is thus offset from the
axis of the bolus toward the venous port.
[0034] The opposite side surfaces of the bolus, proceeding forward
from the mid-point of the venous port, also taper inwardly in
converging arcs to the bullet nose section. Thus, the bolus nose
section is both narrower in width and thinner in height than the
trailing remainder of the bolus and the catheter tube itself.
[0035] Where the passage section joins the nose section of the
bolus, on a plane extending transversely through the bolus in front
of the venous port, the nose section has a maximum thickness in the
plane on a line passing through the bolus axis and the center of
the venous port. The thickness of the nose section is 20% to 25%
less than the diameter of the catheter tube itself. The plane is
inclined forwardly away from the port at an angle corresponding to
the angle of inclination of the curving passage section toward the
bolus axis.
[0036] The nose section of the bolus, being not as thick as the
rest of the bolus but displaced radially to the venous port side of
the longitudinal axis of the bolus passage section and catheter
tube, is in a position wherein a portion of its outermost periphery
is tangent to an imaginary cylinder containing the outer surface of
the bolus passage section at the trailing edge of the venous port.
This offset nose configuration prevents the vein wall from wrapping
around the trailing edge of the port and being abraded thereby.
[0037] The stiffening arch defined in the bolus opposite the venous
port inhibits folding of the bolus at the venous port during
insertion of the catheter. Immediately opposite the arterial port,
another stiffening arch is also formed in the bolus. The arch
extends along that side of the bolus from a point radially aligned
with the trailing edge of the arterial port to the trailing edge of
the venous port. This arch inhibits folding of the bolus around the
arterial port.
[0038] The catheter of the invention, with its novel bolus, lends
itself ideally to insertion in a patient's vein over a guide wire.
When inserted through the vein the bullet nose section flexes
radially outwardly in a plane passing through the bolus axis and
both ports under the influence of the guide wire. Because the nose
section has a smaller thickness in that plane than the rest of the
bolus and the tube, however, it is not forced outside the imaginary
cylinder of the catheter. This makes for ease of insertion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The invention, including its construction and method of
operation, is illustrated more or less diagrammatically in the
drawings in which:
[0040] FIG. 1 is a side elevational view of a portion of a
hemodialysis catheter embodying features of the invention;
[0041] FIG. 2 is a front end view of the catheter bolus;
[0042] FIG. 3 is a bottom plan view of the bolus end of the
catheter of FIG. 1;
[0043] FIG. 4 is a top plan view of the bolus for the catheter of
FIG. 1;
[0044] FIG. 5 is a longitudinal sectional view taken through the
bolus of the catheter of FIG. 4;
[0045] FIG. 6 is a cross-sectional view taken along line 6-6 of
FIG. 1;
[0046] FIG. 7 is a cross-sectional view taken along line 7-7 of
FIG. 1;
[0047] FIG. 8 is a cross-sectional view taken along line 8-8 of
FIG. 1;
[0048] FIG. 9 is a cross-sectional view taken along line 9-9 of
FIG. 1;
[0049] FIG. 9 is a cross-sectional view taken along line 10-10 of
FIG. 1;
[0050] FIG. 11 is a longitudinal sectional view through a patient's
vein with a catheter in-situ in a typical operational position;
[0051] FIG. 12 is a longitudinal sectional view similar to FIG. 5
showing the bolus nose section flexed upwardly by a guide wire;
[0052] FIG. 13 is a longitudinal sectional view of a catheter being
inserted over a guide wire through a patient's vein;
[0053] FIG. 14 is a longitudinal sectional view of a catheter
prepared for introduction into a patient's vein over a guide wire
and through an introducer tube;
[0054] FIG. 15 is a bottom plan view of a catheter bolus and guide
wire showing their relative orientation as the catheter is led
around a turn in a patient's vein;
[0055] FIG. 16 is a longitudinal sectional view taken along line
16-16 of FIG. 15; and
[0056] FIG. 17 is a cross-sectional view taken along line 17-17 of
FIG. 15.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0057] Referring now to the drawings and particularly to FIGS. 1-4,
a dual lumen catheter embodying features of the invention is
illustrated generally at 10. The catheter 10 comprises a
cylindrical tube 11 (only partially shown) having a distal end 15.
A bolus 20 is attached to the distal end 15 of the tube 11.
[0058] Referring now also to FIGS. 5-10, the tube 11 illustrated is
a 14.5 French tube formed of a plastic material such silicone or
polyurethane. In its preferred form, the tube is formed of
MED-4700-A&B silicone manufactured by NuSil Technologies. The
tube 11 is formed by extruding a tubular body 24 with a generally
cylindrical wall 29 and a septum 26. The 14.9 French tube 11 has an
O.D. of 0.192 inches.
[0059] The tube body 24 is divided by the septum 26 into two
identical Dshape lumens 27A and 27B extending through the tube body
along its length. The lumen 27A is normally an arterial lumen and
the lumen 27B is normally a venous lumen. Each lumen 27A and 27B
has a D-shape cross-sectional area of about 0.006 in.sup.2 in a
14.5 French dual lumen tube.
[0060] The distal end 15 of the dual lumen tube body 24 has a
necked down end 32 which is seated in a suitably formed socket 24
in the bolus 20. The bolus 20 has a body 51 also formed of silicone
or polyurethane. The tube 11 and bolus 20 are mated in this
relationship after each is formed. When silicone is used, for
example, and the combination is cured, mated portions of the tube
11 and the bolus 20 are effectively welded together.
[0061] The bolus body 51 includes a tube connector section 55, a
flow passage section 56 and a nose section 57. The flow passage
section 55 has a septum 58 formed in it. The septum 58 mates,
end-to-end, with the septum 26 in the tube body 24, and they are
welded together.
[0062] The septum 58 forms upper and lower passages 59A and 59B in
the flow passage section 56. The upper passage 59A is normally an
arterial passage. The lower passage 59B is normally a venous
passage.
[0063] The upper arterial passage 59A has a D-shape cross-section
and extends forwardly with, and above, the septum 58 to the radial
arterial port 37. Like the lumen 27A, the passage 59A has a
cross-sectional area of about 0.006 in.sup.2. The radial arterial
port 37 extends circumferentially around the body's axis from the
upper surface of the septum 58 on one side of the tube to the upper
surface of the septum on its other side. The leading edge 73 of the
bolus body 51 above the passage 59A, which forms the trailing edge
of the port 37, is rounded along its length down to the septum 58
(see FIG. 4).
[0064] Forward of the arterial port 37 the bolus body 51 becomes
solid, as at 76. In effect, the arterial passage 59A disappears and
the septum 58 melds into this solid portion 76 of the bolus body
51.
[0065] Meanwhile, the venous passage 59B has a D-shape
cross-section portion with a cross-sectional area of about 0.006
in.sup.2 extending forwardly until the septum 58 ends. The venous
passage 59B then gradually increases in size as it changes from a
D-shape to a circular cross-section, as seen in FIG. 6. The
circular cross-section of the passage 59B at the section line 6-6
has a cross-sectional area of about 0.007 in.sup.2.
[0066] The cross-section of the passage 59B becomes fully circular
(at section line 6-6) where it emerges over a base 78 which curves
across the body 51 to form the front end of an axially elongated
main outflow or venous port 89 in the body. The port 89 extends
circumferentially around the body 51 to its side edges 71, as seen
in FIG. 10. There it will be seen that the port 89 extends around
approximately 230.degree. of the circular cross-section passage 59B
where it opens over the base 78 of the port. The port 89 has a
trailing edge 91. The edge 91 is semi-circular in cross-section
rounded along its length (see FIG. 5).
[0067] Where the port 89 begins, at its trailing edge 91, the outer
surface of the solid portion 76 in the bolus body 51 opposite the
port begins to curve inwardly to form a stiffening arch 93. The
curve continues to where the arch 93 joins the nose section 57 at
the base 95 of this section and then forwardly to the rounded
bullet nose 99 on the nose section. The effective longitudinal axis
Y of the passage section 57 forward of the trailing edge 91 of the
port 89 is inclined to the longitudinal axis X of the trailing
portion of the bolus body 51 at an angle of 9.degree.. The arch 93
stiffens the bolus body 51 opposite the port 89 to prevent folding
or kinking of the bolus 20 at that point as it travels through a
vein during insertion.
[0068] Meanwhile, opposite the port 37 and behind the port 89, the
bolus body is curved outwardly and then inwardly to form a
stiffening arch 98. The arch 98 stiffens the bolus body 51 in the
region of the port 37. The arch 98 serves to prevent folding or
kinking of the bolus body 51 during insertion.
[0069] The side surfaces 101 and 102 of the bolus body 51, forward
of the mid-point in the axially elongated port 89 and bracketing
the arch 93, also curve inwardly to the nose section 57. This shape
inhibits lateral flexing of the bolus nose section 57 during
insertion.
[0070] The nose section 57 has a slightly elliptical shape in
cross-section on the inclined plane P where it meets the nose
section (see FIG. 9). The plane P is inclined forwardly relative to
the axis X at an angle of about 81.degree.. On the plane P, the
nose section 57 is smaller in both width and thickness than the
14.5 French tube 11. In its preferred form, it is only about 10
French in size at this point and has a thickness of 0.150 inches
which is 22% less than the diameter of the tube 11. In addition,
the center of the nose section 57 on the axis Y is offset from the
center of the bolus body 51 in the direction of the port 89.
[0071] The aforedescribed size, shape and orientation of the nose
section 57 in the bolus body 51 provides several important
advantages in use of the catheter 10. First, its smaller size
facilitates easy entry into, and travel through, a patient's vein
by the bolus 20. Second, the offset nose section 57 places a
portion of its periphery tangent to a hypothetical cylinder in
which the outer surface of the bolus passage section 56 lies, even
though it is considerably thinner than the remainder of the bolus.
This prevents the vein wall from wrapping inwardly about the edge
91 of the port 89 and the edge then abrading the vein wall. Third,
when guide wire insertion is employed, the nose section 57 flexes
radially away from the wire where it emerges from the port 89,
without forcing either the nose section or the wire substantially
outside the aforementioned cylinder into the vein wall. Fourth,
when traveling around curves in a vein during insertion, the bolus
nose resists bending sideways and catching on the vein wall.
[0072] In regard to the second advantage referred to, attention is
invited to FIG. 11 which shows the catheter 10 in a typical
position in a vein V. There it will be seen that the periphery of
the nose section 57 engages a vein wall when the passage section 56
does. This prevents the trailing edge 91 of the port 89 from having
the vein wall wrap on it and become abraded.
[0073] During insertion, as seen in FIG. 12, the guide wire W
causes the nose section 57 to flex outwardly until its axis Y is
substantially parallel to the axis X of the bolus. However, the
nose section 57, having a smaller cross section generally and a
smaller thickness particularly, does not protrude measurably
outside the aforementioned cylinder. FIG. 13 shows the relative
dimensions of the bolus 20 of the invention on a 10.5 French tube
as it is inserted over a wire W, the inclined nose section 57 being
flexed radially by the wire W but not outside the aforedescribed
hypothetical cylinder. There it will be seen that the diameter of
the tube 11 is 0.192 inches while the combined thickness of the
wire W and nose section 57 is 0.188 inches.
[0074] As seen in FIG. 14, when the catheter 10 is inserted into an
introducer tube T, the hose section 57 of the bolus 20 flexes
upwardly to let the wire W pass. Because the nose section 57 has a
smaller cross-section than the rest of the bolus body 51 and the
tube 11, it is not compressed against the vein wall and frictional
resistance to its passage is not measurably increased.
[0075] FIGS. 15-17 illustrate the catheter bolus 20 following the
guide wire W around a turn in a vein (not shown). Here it will be
seen that the wire W moves to one side of the nose section 57 and
nestles alongside it.
[0076] The bolus 57 sides curve inwardly from the mid-point of the
port 89 forward, as has previously been pointed out. This shape
tends to stiffen the bolus tip against lateral flexing.
[0077] With the catheter 10 in use in a patient, it has a number of
important operational characteristics, some of which will be
emphasized here. Because the lumen 59B in the bolus body 51
increases in size and becomes circular in cross-section as it
approaches the port 89, pressure decreases, flow is more uniform
and dialyzed blood is discharged through the venous port under less
force. Should the arterial port 37 become clogged, the flow can be
reversed to introduce dialyzed blood through port 37 and clear the
port 37. Since the port 89 is relatively far removed from the port
37, dialyzed blood is not sucked directly into the port 89.
[0078] The present invention provides the physician with a bullet
nose catheter 10 which can be inserted using a guide wire W but
which does not require perforation of the bolus nose to facilitate
passage of the guide wire. The nose section 57 of the bolus 20
flexes away from the bolus axis X to permit passage of the wire W
but, in doing so, does not protrude measurably outside the
imaginary cylinder defined by the rest of the bolus and the
catheter tube, whereby the pressure of the bolus on vein V wall is
not increased. Nevertheless, with the catheter 10 in operational
position in a patient's vein V and the wire W removed, the nose
section returns 57 to its normal position wherein it prevents the
vein wall from wrapping around the bolus port edge 91 and becoming
abraded thereby.
[0079] While a preferred embodiment of the invention has been
described, it should be understood that the invention is not so
limited and modifications may be made without departing from the
invention. The scope of the invention is defined by the appended
claims, and all devices that come within the meaning of the claims,
either literally or by equivalence, are intended to be embraced
therein.
* * * * *