U.S. patent application number 15/239390 was filed with the patent office on 2016-12-08 for cannular device and method of manufacture.
The applicant listed for this patent is Medtronic, Inc.. Invention is credited to Roger Warren Brink, Christopher Alan Oleksy.
Application Number | 20160354532 15/239390 |
Document ID | / |
Family ID | 45934748 |
Filed Date | 2016-12-08 |
United States Patent
Application |
20160354532 |
Kind Code |
A1 |
Oleksy; Christopher Alan ;
et al. |
December 8, 2016 |
Cannular Device and Method of Manufacture
Abstract
A cannula comprising a polymeric material which is
phthalate-free, yet retains flexibility, workability and elongation
properties so as to avoid kinking when bent. Also disclosed is a
method of manufacturing a cannular device comprising extruding a
flexible, biocompatible, phthalate-free polymeric composition
through a round die into a tube, pulling the tube through a water
bath at a rate established according to a predetermined function,
and cutting the tube to for a cannular device, wherein the
predetermined function periodically modulates a pulling rate.
Inventors: |
Oleksy; Christopher Alan;
(Maple Grove, MN) ; Brink; Roger Warren;
(Muskegon, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic, Inc. |
Mounds View |
MN |
US |
|
|
Family ID: |
45934748 |
Appl. No.: |
15/239390 |
Filed: |
August 17, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13042798 |
Mar 8, 2011 |
9446216 |
|
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15239390 |
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61393167 |
Oct 14, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 55/22 20130101;
A61M 2207/00 20130101; A61L 29/06 20130101; B29C 48/13 20190201;
B29L 2031/7542 20130101; B29K 2021/003 20130101; B29C 48/10
20190201; B29L 2023/007 20130101; B29K 2995/0056 20130101; B29C
48/09 20190201; A61M 1/3659 20140204; B29C 48/919 20190201; A61L
29/041 20130101; B29C 2948/92876 20190201; A61M 2025/0059 20130101;
A61M 25/0023 20130101; A61L 29/14 20130101; A61M 25/0043 20130101;
B29C 2948/92704 20190201; B29C 48/0022 20190201; A61M 25/0009
20130101; A61M 25/0021 20130101 |
International
Class: |
A61M 1/36 20060101
A61M001/36; B29C 47/88 20060101 B29C047/88; B29C 55/22 20060101
B29C055/22; B29C 47/00 20060101 B29C047/00 |
Claims
1-22. (canceled)
23. A method of manufacturing a cannular device, comprising:
extruding a flexible, biocompatible, phthalate-free polymeric
composition through a round die into a tube; pulling the tube
through a water bath at a rate established according to a
predetermined function; and cutting the tube to form a cannular
device; wherein the predetermined function periodically modulates a
pulling rate.
24. The method of claim 23, wherein the predetermined function
provides periods in which the pulling rate increases from a minimal
pulling rate to a maximal pulling and periods in which the pulling
rate decreases from a maximal pulling rate to a minimal pulling
rate so that the tube is formed having an oscillating
cross-sectional diameter that changes with time.
25. The method of claim 24, wherein the predetermined function
further provides periods in which the pulling rate is not
modulated.
26. The method of claim 25, wherein the predetermined function
further provides that the periods in which the pulling rate is not
modulated are interposed between periods in which the pulling rate
is modulated.
27. The method of claim 25, wherein the cut tube is adapted to
resist kinking when tested according to an 180.degree. bend
test.
28. The method of claim 25, wherein the polymeric composition is
free of plasticizers.
29. The method of claim 25, wherein the polymeric composition
comprises a thermoplastic elastomer.
30. The method of claim 29, wherein the thermoplastic elastomer has
a Shore A hardness in a range from about 45 to about 85.
31. The method of claim 25, wherein the tube is adapted for
recovering to full patency to cause the inner lumen to remain free
from obstruction after being clamped to complete closure.
32. The method of claim 25, wherein the cut tube has a circular
cross-section defining an inner diameter and an outer diameter, the
circular cross-section diminishing in size along a length from a
first inner diameter and a first outer diameter to a second inner
diameter and a second outer diameter, the first inner diameter
being larger than the second inner diameter and the first outer
diameter being larger than the second outer diameter.
33. The method of claim 25, wherein the cut tube has a proximal end
and a distal end, the proximal end having a first inner diameter
and a first outer diameter defining a first thickness, the distal
end having a second inner diameter and a second outer diameter
defining a second thickness, wherein the second thickness is about
50 to about 95% of the first thickness.
34. The method of claim 25, wherein the tube is sufficiently clear
so that fluids passing through the tube can be observed.
35. The method of claim 25, wherein the cut tube has a proximal end
and a distal end, wherein the cut tube is tapered from the proximal
end to the distal end.
36. A method of manufacturing a cannular device, comprising:
extruding a flexible, biocompatible, phthalate-free polymeric
composition through a round die into a tube; pulling the tube
through a water bath at a rate established according to a
predetermined function; and cutting the tube to form a cannular
device; wherein the predetermined function provides periods in
which the pulling rate increases from a minimal pulling rate to a
maximal pulling and periods in which the pulling rate decreases
from a maximal pulling rate to a minimal pulling rate so that the
tube is formed having an oscillating cross-sectional diameter that
changes with time; wherein the cut tube has a proximal end and a
distal end, the proximal end having a first inner diameter and a
first outer diameter defining a first thickness, the distal end
having a second inner diameter and a second outer diameter defining
a second thickness, wherein the second thickness is about 50 to
about 95% of the first thickness.
36. A method of manufacturing a cannular device, comprising:
extruding a flexible, biocompatible, phthalate-free polymeric
composition through a round die into a tube; pulling the tube
through a water bath at a rate established according to a
predetermined function; and cutting the tube to form a cannular
device; wherein the tube is adapted to resist kinking and to
recover to full patency after being clamped to complete closure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims benefit of copending U.S.
Provisional Patent Application No. 61/393,167, filed Oct. 14, 2010,
entitled CANNULAR DEVICE AND METHOD OF MANUFACTURE, and commonly
assigned to the assignee of the present application, the disclosure
of which is incorporated by reference in its entirety herein.
BACKGROUND
[0002] The present disclosure relates to polymeric tubular conduit
for insertion into the body and methods of manufacturing the same.
The conduit comprises a polymeric material combinable with other
suitable components for cannulation in medical applications.
[0003] Cannulation is a process of introducing a cannula into the
body of a patient (e.g., body cavity, duct or blood vessel, organ,
or the like) for the introduction or removal of fluids (e.g.,
blood, medications, or air) or devices (e.g., catheter). The
cannula may be used for short periods of time (e.g., during
surgery) or for extended periods (e.g., extracorporeal membrane
oxygenation (ECMO)). For example, surgical procedures related to a
patient's heart may require the blood flow through the heart be
by-passed in favor of an extracorporeal circulation device (e.g., a
heart lung machine). A heart lung machine can be used to circulate
and oxygenate blood while the patient's heart is being repaired.
The heart lung machine is coupled to the patient's vascular system
through specialized conduits called cannulae (plural of cannula).
Cannulae adapted to receive blood from the body and transmit the
blood to the heart lung machine are called venous cannulae.
Cannulae adapted to return blood from the heart lung machine back
to the body are called arterial cannulae.
[0004] Cannulae were used in human heart bypass surgeries as early
as the 1950's. Since then, the overall designs of the most widely
used arterial and venous cannula have not changed dramatically.
Historically, cannulae are semi-rigid components often made of
polyvinyl chloride (PVC) secured by sutures in the patient's
arterial and venous structures. When a cannula is made from PVC,
plasticizers are often used to provide the PVC, a highly rigid
polymer without plasticizers, with the appropriate properties. A
plasticizer is an additive that increases a polymer's flexibility,
workability, and ability to be elongated. Plasticizers essentially
lubricate the polymer chains in a polymer composition so that the
intermolecular forces between and along the chains are reduced.
This loosening of the intermolecular forces allows the polymer
chains to slide across each other more freely.
[0005] Most plasticizers are organic compounds with elevated,
boiling points, low vapor pressures, and poor water solubility. For
example, ester phthalates are regularly used because of their
particular effectiveness in lubricating polymeric materials.
Currently, two commonly used plasticizers are di-2-ethylhexyl
phthalate (DEHP) and di-isononyl phthalate (DINP) both of which are
phthalates. These plasticizers are routinely used with PVC to make
a variety of products. For example, many medical products, toys,
and baby products include components comprising PVC and a
plasticizer like DEHP. The incorporation of the plasticizers into
PVC products provides the composition with the soft, flexible, and
supple feel that is associated with these products.
[0006] Plasticizers can be compounded with the polymeric materials
with which they are used. Most plasticizers do not react to form
any chemical bonds with the polymer. Essentially, the plasticizer
is dissolved within the polymeric material because of the favorable
physical interactions between the polymer and the plasticizer. The
favorable physical interactions typically prevent the plasticizer
from leaching out of the polymer. While plasticizers are typically
not water soluble, they are soluble in non-polar solvents and are
known to be slightly soluble in blood and other bodily fluids.
Accordingly, in a cannula manufactured with a plasticizer an amount
of plasticizer may be leached out in vivo and become dissolved in
bodily fluids. For example, a publication by Peck and Albro,
Environmental Health Perspectives Vol. 45, pp. 11-17, 1982, found
that DEHP plasticizer from a PVC/DEHP blood bag accumulate in
plasma during 4.degree. C. liquid whole blood storage at a rate of
approximately 1 mg/unit/day. There has been extensive research and
debate surrounding the toxicological impact of DEHP in biological
fluid. The results have been inconsistent and there is not a clear
answer as to whether and to what extent such plasticizers may be a
health risk to patients. It would be desirable to produce a
cannular device which is free of plasticizers yet will provide the
desired properties of flexibility, workability and ability to be
elongated.
SUMMARY
[0007] The present disclosure provides in one exemplary embodiment
a polymeric tubular conduit for use in patients and methods of
manufacturing the same. The conduit comprises a polymeric material
combinable with other suitable components for cannulation in
medical applications.
[0008] In one illustrative embodiment, a cannular device of the
present disclosure comprises a polymeric conduit having an inner
lumen, a proximal end having a proximal opening, and a distal end
having a distal opening, arranged so that the inner lumen extends
from the proximal opening to the distal opening. The polymeric
conduit comprises a biocompatible polymeric composition free of
plasticizers, for example (but not by way of limitation) free of
di-2-ethylhexyl phthalate (DEHP), DINP or other phthalate-based
compound. The polymeric conduit may be arranged to have a circular,
elliptical, oval or other cross-section shape defining an inner
diameter and an outer diameter. The cross-section diameter may
diminish in size from the proximal end to the distal end from a
first inner diameter and first outer diameter to a second inner
diameter and a second outer diameter. The first inner diameter may
be larger than the second inner diameter and the first outer
diameter may be larger than the second outer diameter. The
polymeric conduit is adapted to resist kinking so that the inner
lumen remains free from obstruction when tested according to a
standard 180.degree. bend test. The inner diameter of the polymeric
conduit may diminish according to a first continuous function, the
function providing a gradual diminution of diameter from the
proximal end to the distal end. The outer diameter may diminish
according to a second continuous function, the function providing a
gradual diminution of size from the proximal end to the distal
end.
[0009] In one illustrative embodiment, a method of manufacturing a
cannular device in accordance with the present disclosure comprises
extruding a flexible, biocompatible, phthalate-free polymeric
composition through a round die into a tube, pulling the tube
through a water bath at a rate established according to a
predetermined function, and cutting the tube to form the cannular
device. The predetermined function periodically modulates a pulling
rate. The predetermined function may also provide periods of time
in which the pulling rate increases from a minimal pulling rate to
a maximal pulling and periods of time in which the pulling rate
decreases from a maximal pulling rate to a minimal pulling rate.
The modulation of the pulling rate according to this function
provides the tube with an oscillating cross-sectional diameter
changing with time. The predetermined function may also provide
periods in which the pulling rates are not modulated. In one
illustrative embodiment, the periods in which the pulling rates are
not modulated are interposed between periods in which the pulling
rates are modulated.
BRIEF DESCRIPTION OF DRAWINGS
[0010] So the manner in which the above-recited features of the
present disclosure can be understood in detail, a more particular
description of the present disclosure may be had by reference to
embodiments, which are illustrated in the appended drawings. It is
to be noted, however, that the appended drawings illustrate only
typical embodiments encompassed within the scope of the present
disclosure, and, therefore, are not to be considered limiting, for
the present invention may admit to other equally of effective
embodiments, wherein:
[0011] FIG. 1 is a perspective view of a first exemplary embodiment
of cannular device having a proximal end and proximal opening, a
distal end and distal opening, and an interior conduit defined
between the proximal opening and the distal opening;
[0012] FIG. 2 is an end view shown in FIG. 1 of the proximal
opening showing that at the proximal opening the conduit has a
first outer diameter, a first inner diameter, and a first wall
thickness;
[0013] FIG. 3 is an end view of the distal opening shown in FIG. 1
showing that at the distal opening the conduit has a second outer
diameter, a second inner diameter, and a second wall thickness;
[0014] FIG. 4 is a perspective view of the device of FIG. 1
subjected to a 180.degree. bend test showing that the device does
not kink when so tested; and
[0015] FIG. 5 is a perspective view of a prior art device made
through a dip-molding process showing that the device includes a
wire-wound body to avoid kinking.
DETAILED DESCRIPTION
[0016] Referring now to FIG. 1, shown is a perspective view of a
first exemplary embodiment of a cannular device 10 having a
proximal end 11 and proximal opening 21, a distal end 12 and a
distal opening 22, and an interior lumen 31 defined therein between
proximal opening 21 and distal opening 22. FIG. 2 is an end view of
proximal opening 21 showing that at the proximal opening the
conduit has a first outer diameter D1, a first inner diameter D2,
and a first wall thickness D5. FIG. 3 is an end view of distal
opening 22 showing that at distal opening 22 the conduit has a
second outer diameter D3, a second inner diameter D4, and a second
wall thickness D6.
[0017] The use of cannular devices in cardiac surgery makes
particular cannular designs preferable over others. For example,
cannulae designs that maximize fluid flow are more desirable than
those with lesser flow capabilities. While maximizing flow is
desirable, surgeons must balance the need for flow against the
trauma that a given cannular device may impart upon the recipient
body. Thus, a desirable cannula design generally includes the
largest internal diameter cannula (for flow) that has an outer
diameter that can be atraumatically inserted into the body. Thus,
maximum distal external diameter (e.g., second outer diameter D3)
is limited to the size of the bodily member in which the cannular
device is inserted. For example, a cannular device having an
external diameter larger than the blood vessel could not be
inserted therein. Furthermore, there are standard connection sizes
for the proximal opening (first inner diameter D2) that makes
certain sizes desirable. For example, many connectors are sized at
3/16, 1/4, 3/8, 4/10 inches, etc.
[0018] In addition to the basic dimensional size requirements of a
cannular device, the shape of the cannular device influences the
turbulence of flow of fluid through the device. Abrupt changes in
the shape or cross-sectional area of a cannular device may cause
turbulent flow characteristics. An abrupt expansion, contraction,
or change in flow direction may have an adverse affect on the fluid
being transmitted. Thus, some device geometries may be favorable to
others due to their internal flow characteristics during use.
[0019] For a cannular device to be selected by a surgeon, there are
certain dimensional characteristics that are desirable. For
example, the proximal opening should facilitate the use of various
connectors or enable the cannular device to be directly connected
to extracorporeal tubing. The distal opening should facilitate the
use of various tips or have dimensions and shapes suitable for
direct insertion into the body. FIG. 1 is an exemplary cannular
device shape that is known to possess these desirable dimensional
characteristics. With respect to cannular device 10, it includes a
gradually tapered diameter that is free of abrupt size changes.
[0020] In one illustrative embodiment, a cannular device of the
present disclosure comprises a polymeric conduit defining an inner
lumen, a proximal end having a proximal opening, and a distal end
having a distal opening arranged so that the inner lumen extends
from the proximal opening to the distal opening. The polymeric
conduit comprises a biocompatible polymeric composition free of
plasticizers, for example free of di-2-ethylhexyl phthalate.
Cannular devices manufactured with polyvinyl chloride (PVC) contain
substantial concentrations of plasticizers such as di-2-ethylhexyl
phthalate. In one embodiment, the cannular devices of the present
disclose are not manufactured using PVC or plasticizers. In another
embodiment, the cannular devices of the present disclosure are not
manufactured with phthalates.
[0021] In one illustrative embodiment, a cannular device includes a
polymeric composition comprising a thermoplastic elastomer (TPE).
One aspect of the present disclosure is that it was discovered that
thermoplastic elastomers may be used in place of PVC and
plasticizers. As used herein, thermoplastic elastamers means
polymeric materials having the flexibility properties like rubbers,
strength properties like plastics, and processability properties
like thermoplastics. Illustratively, a thermoplastic elastomer may
be sufficiently elastomeric to return to its original shape (or
nearly do so) after moderate elongation. Further illustratively, a
thermoplastic elastomer may be sufficiently thermoplastic to enable
melt processability while substantially avoiding creep at mom
temperature. Thus, a thermoplastic elastomer may be partially
characterized by the absence of significant creep while having
thermoplastic and elastomeric properties.
[0022] Thermoplastic elastomers are distinct from thermosetting
elastomers because thermosetting materials (generally) become rigid
upon processing (though there are some elastomers which have
properties of both classes). A thermosetting elastomer would
generally not be useful within the scope of the present disclosure
because it would loose its flexibility upon cooling after exposure
to processing temperatures. In contrast, thermoplastic materials
are considered easy to use in manufacturing because they maintain
their properties through a thermo-forming process. For example, a
thermoplastic material would have similar properties before and
after a manufacturing procedure such as injection molding. The
difference in a thermoplastic elastomer and a thermosetting
elastomer can be traced to the different chemical interactions that
provide the differing physical properties. For thermosetting
elastomers, covalent crosslinks may form as the result of a
processing step (e.g., vulcanization). The formation of covalent
crosslinks permanently changes the chemical structure of the
polymer so that material's properties change substantially.
Thermoplastic elastomers include weaker crosslinking moieties that
rely on dipole-dipole interactions or hydrogen bonding. During a
processing step, these weak crosslinks lose the ability to restrict
the shape of the material due to its thermal energy (i.e., the
material melts), but upon cooling, the weak bonds reform and again
have sufficient strength to keep the material's shape constant
(i.e., solidification).
[0023] The term "thermoplastic elastomer" covers a broad range of
chemical compositions with dramatically different chemical and
physical properties. Representative thermoplastic elastomers
include, but are not limited to, styrenic block copolymers,
polyolefin blends elastomeric alloys, thermoplastic polyurethanes,
thermoplastic copolyesters and thermoplastic polyamides. There are
a number of chemical manufacturers providing a wide range of TPE
products under various trade names, for example: EXELAST SX.RTM.
(Shin-Etsu Polymer Europe B.V.), STYROFLEX.RTM., ELASTOLLAN.RTM.
(BASF & Elastogran), PEARLTHANE.RTM. (Merquinsa), DESMOPAN.RTM.
(Bayer), ESTANE.RTM. (Lubrizol), IROGRAN.RTM. (Huntsman),
PELLETHANE.RTM., ENGAGE.RTM. (Dow Chemical), PEBAX.RTM.,
ARNITEL.RTM., SARLINK.RTM. (DSM), HYTREL (Du Pont), DRYFLEX.RTM.,
MEDIPRENE.RTM. (ELASTO, Hexpol Company), VERSAFLEX.RTM. (PolyOne
GLS), SANTOPRENE.RTM. (ExxonMobil Chemical), KRATON.RTM. (Kraton
Polymers), and PEBAX.RTM. (Arkema).
[0024] There are virtually limitless TPE compositions and blends
thereof that may or may not provide useful properties within the
scope of the present disclosure. One aspect of the present
disclosure is that the attributes of preferred compositions are set
forth so that one skilled in the art may appreciate those
compositions useful for applications as described herein.
[0025] In one illustrative embodiment, a thermoplastic elastomer
has a Durometer hardness (Shore A, 10 sec) as determined according
to ASTM D2240 of about 45 to about 85. In one embodiment, the
thermoplastic elastomer has a Durometer hardness of about 55 to
about 75. In another embodiment, the thermoplastic elastomer has a
Durometer hardness of about 60 to about 70. In yet another
embodiment, the thermoplastic elastomer has a Durometer hardness of
about 65. Another aspect of the present disclosure is that it was
discovered that the physical dimensions of a particular cannular
device may require a TPE with having a particular Durometer
hardnesses. Illustratively, a TPE having a higher hardness was
determined to be better suited for a cannular device having a small
diameter and thin walls. In contrast, it was determined that a TPE
having lower hardness provided enhanced properties in those
cannular devices having larger diameters and thicker walls.
[0026] In one illustrative embodiment, the thermoplastic elastomer
has a density as determined according to ASTM D792 of about 0.80
g/cm.sup.3 to about 0.95 g/cm.sup.3. In one embodiment, the
thermoplastic elastomer has a density of about 0.83 g/cm.sup.3 to
about 0.92 g/cm.sup.3. In another embodiment, the thermoplastic
elastomer has a density of about 0.86 g/cm.sup.3 to about 0.89
g/cm.sup.3. In yet another embodiment, the thermoplastic elastomer
has a density of about 0.88 g/cm.sup.3.
[0027] In one illustrative embodiment, the thermoplastic elastomer
has a tensile stress (100% Strain, 73.degree. F.) of about 100 psi
to about 500 psi as determined according to ASTM D421. In one
embodiment, the thermoplastic elastomer has a tensile stress (100%
Strain, 73.degree. F.) of about 150 psi to about 400 psi. In
another embodiment, the thermoplastic elastomer has a tensile
stress (100% Strain, 73.degree. F.) of about 200 psi to about 350
psi. In yet embodiment, the thermoplastic elastomer has a tensile
stress (100% Strain, 73.degree. F.) of about 280 psi.
[0028] In one illustrative embodiment, the thermoplastic elastomer
has a tensile strength of about 600 psi to about 1800 psi and an
elongation to break of about 300% to 900% as determined according
to ASTM D421. In one embodiment, the thermoplastic elastomer has a
tensile strength of about 900 psi to about 1500 psi and an
elongation to break of about 450% to 750%. In another embodiment,
the thermoplastic elastomer has a tensile strength of about 1200
psi and an elongation to break of about 650%.
[0029] In one illustrative embodiment, the thermoplastic elastomer
is selected and adapted so that the surface (generally exterior) of
the cannular device accepts ink upon printing. Thermoplastic
elastomers vary significantly on their receptiveness to being
printed, in many of the medical applications that a cannular device
of the present disclosure is used, the cannular device should
include markings for identification or for the assistance of the
surgeon during use. Accordingly, the combination of the TPE, as
disclosed herein and method of manufacture provide a cannular
device that accepts ink upon printing.
[0030] In one illustrative embodiment, the thermoplastic elastomer
can be bump extruded at a melt temperature of about 150.degree. C.
to about 250.degree. C. and a die temperature of about 140.degree.
C. to about 240.degree. C. In one embodiment, the thermoplastic
elastomer can be bump extruded at a melt temperature of about
170.degree. C. to about 220.degree. C. and a die temperature of
about 160.degree. C. to about 210.degree. C. In another embodiment,
the thermoplastic elastomer can be bump extruded at a melt
temperature of about 180.degree. C. to about 205.degree. C. and a
die temperature of about 170.degree. C. to about 200.degree. C.
[0031] In one illustrative embodiment, upon extruding the
thermoplastic elastomer, it is sufficiently clear so that the
fluids passing through the lumen can he adequately observed. The
clarity of the cannular device can be tested by visually inspecting
high contrast markings through the cannular device. A failing
cannular device inhibits the visual determination of the high
contrast markings. A passing device allows for the visual
determination of the high contrast markings. As a standard
reference material, a cannular device manufactured using PVC and
plasticizers can be used for comparison to the devices described
herein. One aspect of the present disclosure is that the
combination of the TPE, as disclosed herein, the cannular design
(e.g., thickness of walls, extent of taper, length, diameters,
taper rates, and smoothness), and method of manufacture provide a
sufficiently clear cannula for use in medical procedures.
[0032] In one illustrative embodiment, the cannular device includes
a polymeric, conduit that is arranged to have a circular
cross-section defining an inner diameter and an outer diameter, the
circular cross-section may diminish in size from the proximal end
to the distal end from a first inner diameter and first outer
diameter to a second inner diameter and a second outer diameter.
The first inner diameter is larger than the second inner diameter
and the first outer diameter is larger than the second outer
diameter. Illustratively, the shape of the cannular device is
tapered from the proximal end to the distal end. In one
illustrative embodiment, the inner diameter of the proximal end is
less than 1 inch. In one embodiment, the inner diameter of the
proximal end is less than or equal to about 0.75 inches. In another
embodiment, the inner diameter of the proximal end is about 0.4
inches. In another embodiment, the inner diameter of the proximal
end is about 0.375 inches. In another embodiment, the inner
diameter of the proximal end is about 0.375 inches. In another
embodiment, the inner diameter of the proximal end is between about
0.1 inches about 0.25 inches.
[0033] In one illustrative embodiment, the inner diameter of the
distal end is less than 0.75 inches. In one embodiment, the inner
diameter of the distal end is less than about 0.5 inches. In
another embodiment, the inner diameter of the distal end is about
0.25 inches. In another embodiment, the inner diameter of the
distal end is about 0.15 inches. In another embodiment, the inner
diameter of the distal end is between about 0.15 inches about 0.25
inches. In another embodiment, the inner diameter of the distal end
is between about 0.15 inches about 0.05 inches.
[0034] In further one illustrative embodiment, the wall thickness
at the distal end is between about 0.2 inches and 0.005 inches. In
one embodiment, the wall thickness at the distal end is between
about 0.1 and 0.01 inches. In another embodiment, the wall
thickness at the distal end is between about 0.09 and 0.05 inches.
In one illustrative embodiment, the "average wall thickness change
per inch length to diameter change per inch length" ratio was
determined to influence kink resistance. In one embodiment, the
average wall thickness change per inch length to diameter change
per inch length ratio is between about 3 and about 70. In another
embodiment, the average wall thickness change per inch length to
diameter change per inch length ratio is between about 6 and about
35. In another embodiment, the average wall thickness change per
inch length to diameter change per inch length ratio is greater
than about 7.5.
[0035] One aspect of the present disclosure is that the polymeric
conduit is adapted to provide means for resisting kinking so that
the inner lumen remains free from obstruction when tested according
to the 180.degree. bend test. Referring now to FIG. 4, shown is a
perspective view of the device of FIG. 1 subjected to a 180.degree.
bend test showing that the device does not kink when so tested. In
particular, the 180.degree. bend test involves bending the cannular
device so that the distal end and the proximal end are in contact
and oriented in a parallel fashion as shown. A cannular device
failing the 180.degree. bend test would exhibit a crease or kink at
a location 50 in roughly the middle of the device. A cannular
device passing the 180.degree. bend test does not exhibit any kink
or crease over the entire device. One aspect of the present
disclosure is that the combination of the TPE, as disclosed herein,
the cannular design (e.g., thickness of walls, extent of taper,
length, diameters, taper rates, and smoothness), and method of
manufacture provide a robust cannular device that passes the
180.degree. bend test.
[0036] Referring now to FIG. 5, shown is a perspective view of a
prior art device made through a dip-molding process showing that
the device includes a wirewound body to avoid kinking. In one
illustrative embodiment of the present disclosure the polymeric
conduit is wire-free. One aspect of the present disclosure is that
the combination of the TPE, as disclosed herein, the cannular
design (e.g., thickness of walls, extent of taper, length,
diameters, taper rates, and smoothness), and method of manufacture
provide a robust cannular device that passes the 180.degree. bend
test without the inclusion of wire in the device.
[0037] Another aspect of the present disclosure is that the polymer
composition of the conduit is adapted to recover to full patency to
cause the inner lumen to remain free from obstruction after being
clamped to complete closure. Use of the cannular device in medical
procedures may require that the device be clamped so as to stop
flow of a fluid through the lumen of the device. Clamping of the
device exerts significant pressures on the walls of the device, but
recovery to full patency is enabled through the compositions and
described herein. A cannular device failing the clamp test would
either be too stiff to properly clamp, be too "sticky" and one wall
would adhere to the opposite wall thus failing to fully recover its
circular cross-section, be too brittle and crack, or be
insufficiently elastic so that the deformation from the clamp
becomes permanent. A cannular device passing the clamp test would
recover full patency (return to generally the same shape it was
prior to clamping). One aspect of the present disclosure is that
the combination of the TPE, as disclosed herein, the cannular
design (e.g., thickness of walls, extent of taper, length,
diameters, taper rates, and smoothness), and method of manufacture
provide a robust cannular device that passes the clamp test.
[0038] In one illustrative embodiment, the inner diameter of the
polymeric conduit diminishes according to a first continuous
function, the function providing a gradual diminution of diameter
from the proximal end to the distal end. In one embodiment, the
outer diameter diminishes according to a second continuous
function, the function providing a gradual diminution of size from
the proximal end to the distal end. The first continuous function
and the second continuous function may or may not be equivalent so
that the wall thickness at the distal end and the proximal end may
or may not be the same. In one embodiment, the first continuous
function provides a diminution of diameter of about 0.001 to about
0.05 inch per linear inch. In another embodiment, the first
continuous function provides a diminution of diameter of about
0.003 to about 0.03 inch per linear inch. In yet another
embodiment, the first continuous function provides a diminution of
diameter of about 0.003 to about 0.01 inch per linear inch. In one
embodiment, the second continuous function provides a diminution of
diameter of about 0.0001 to about 0.05 inch per linear inch. In yet
another embodiment, the first continuous function provides a
diminution of diameter of about 0.0001 to about 0.03 inch per
linear inch. In another embodiment, the first continuous function
provides a diminution of diameter of about 0.0001 to about 0.01
inch per linear inch. In another embodiment, the first inner
diameter and the first outer diameter define a first thickness for
the polymer conduit at the proximal end opening and the second
inner diameter and the second outer diameter define a second
thickness for the polymer conduit at the distal end, wherein the
second thickness is about 50 to about 95% of the first
thickness.
[0039] In one illustrative embodiment, the change in wall thickness
from the proximal opening to the distal opening decreases according
to a third continuous function, the third continuous function
providing gradual step-less thickness diminution from the proximal
end opening to the distal opening. In one embodiment, the third
continuous function provides a diminution of thickness of about
0.00005 to about 0.005 inch per linear inch. In another embodiment,
the third continuous function provides a diminution of thickness of
about 0.0001 to about 0.003 inch per linear inch. In another
embodiment, the third continuous function provides a diminution of
thickness of about 0.001 to about 0.002 inch per linear inch.
[0040] In one illustrative embodiment, the polymeric conduit is
adapted to provide means for bonding with adhesives to cause tips
and connectors attached thereto with adhesive to remain affixed.
One aspect of the disclosure is that the cannular device shown in
FIG. 1 may be considered a component of a finished medical device.
As such, other components may be combined with the cannular device
shown to produce a cannular device of increased complexity. The
other components may he configured with the illustrated cannular
device through the use of solvent setting, melt fusing, or
adhesives. One aspect of the present disclosure is that the
combination of the TPE, as disclosed herein, the cannular design
(e.g., thickness of walls, extent of taper, length, diameters,
taper rates, and smoothness), and method of manufacture provide
properties that enable the manufacture of cannular devices of
greater complexity. In further one illustrative embodiment, the
polymeric conduit is adapted to provide means for maintaining color
to cause device to retain un-yellowed color during accelerated
aging.
[0041] In one illustrative embodiment, a method of manufacturing a
cannular device in accordance with the present disclosure comprises
extruding a flexible, biocompatible, phthalate-free polymeric
composition through a round die into a tube, pulling the tube
through a water bath at a rate established according to a
predetermined function, and cutting the tube to form the cannular
device. The predetermined function periodically modulates a pulling
rate. The predetermined function may also provide periods of time
in which the pulling rate increases from a minimal pulling rate to
a maximal pulling and periods of time in which the pulling rate
decreases from a maximal pulling rate to a minimal pulling rate.
The modulation of the pulling rate according to this function
provides the tube with an oscillating cross-sectional diameter
changing with time. The predetermined function may also provide
periods in which the pulling rates are not modulated. In one
illustrative embodiment, the periods in which the pulling rates are
not modulated are interposed between periods in which the pulling
rates are modulated.
[0042] Table 1 below depicts comparative test data between cannulae
in accordance with embodiments of the present disclosure, and
cannulae manufactured in accordance with conventional compositions.
The flow test were conducted with BioPump using water. Cannulae
were connected in series with pressure box plumbed into proximal
end with the distal end exhausting into tray. Comparative Examples
A, B, and C are made with phthalate containing PVC having a design
as shown in FIG. 5. Examples 1, 2, and 3, have a design like that
shown in FIG. 1 and are made from a thermoplastic elastomer (GLS
VERSAFLEX.RTM. HC MT222). The Examples 1, 2, and 3 were designed to
have matching dimensions to Comparative Examples A, B, and C. In
particular, Comparative Example A and Example 1 are 14 in (35.6 cm)
in overall length, having a 1/4 in (0.64 cm) diameter proximal
opening (12 Fr (4.0 mm)). Comparative Example B and Example 2 are
14 in (35.6 cm) in overall length, having a 1/4 in (0.64 cm)
diameter proximal opening (20 Fr (6.7 mm)). Comparative Example C
and Example 3 are 8.5 in (21.6 cm) in overall length, having a 3/8
in (0.95 cm) diameter proximal opening (20 Fr (6.7 mm)).
[0043] In addition to the flow test data shown in Table 1, the
following specifications were considered: clarity-comparative and
exemplary devices equivalent, waviness-exemplary devices
acceptable, proximal end squareness-exemplary devices all within
+/-3.degree., room temperature kink-exemplary devices remain
kink-free with 180.degree. bend, 37.degree. C. kink-exemplary
devices remain kink-free with 180.degree. bend, room temperature
clamp-exemplary devices returned to full patency, 37.degree. C.
clamp-exemplary devices returned to full patency, ink
adhesion-exemplary devices acceptable, adhesive bonding-exemplary
devices acceptable, and accelerated aging-exemplary devices showed
acceptable performance at 3 years.
TABLE-US-00001 TABLE 1 A 1 RPM Press. RPM Press. .DELTA. Press. 500
9 500 9 0 1000 39 1000 38 1 1500 87 1510 86 1 2000 150 2010 150 0 B
2 RPM Press. RPM Press. .DELTA. Press. 510 4 510 4 0 1000 19 1000
20 -1 1540 50 1510 49 1 2020 83 2030 87 -4 2530 130 2520 132 -2 C 3
RPM Press. RPM Press. .DELTA. Press. 530 4 530 4 0 1010 17 1000 17
0 1530 42 1520 42 0 2020 72 2030 78 -6
[0044] It is to be understood that the cannular device and method
of producing the device can be adapted for other uses and
applications, such as noninvasive medical devices, drinking straws,
intra venous tubes, and the like. All patents, applications, and
publications referred to herein are incorporated by reference in
their entirety. Although only a number of exemplary embodiments
have been described in detail above, those skilled in the art will
readily appreciate that many modifications are possible in the
exemplary embodiments without materially departing from the novel
teachings and advantages. Accordingly, all such modifications are
intended to be included within the scope of this disclosure as
defined in the following claims
* * * * *