U.S. patent application number 10/766138 was filed with the patent office on 2005-07-28 for medical tubing having variable characteristics and method of making same.
Invention is credited to Adlparvar, Payam, Brustad, John R., Gadberry, Donald L., Hadley, Carl B., Hart, Charles C., Hilal, Nabil, Hilal, Said S., Hilal, Serene, Johnson, Gary M., Petrime, Matthew N., Pingleton, Edward D., Sakakine, Ghassan, Vu, Kenneth K..
Application Number | 20050165366 10/766138 |
Document ID | / |
Family ID | 34795602 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050165366 |
Kind Code |
A1 |
Brustad, John R. ; et
al. |
July 28, 2005 |
Medical tubing having variable characteristics and method of making
same
Abstract
The invention primarily is directed to a medical tubing adapted
for insertion into a body tissue or cavity and method of
manufacturing different variations of the tubing along a length of
the tubing. The tubing comprises a plurality of individual,
discrete, generally ring-shaped elements arranged in series and
fused or bonded together forming a continuous tubular structure.
The ring-shaped elements may be formed of a thermoplastic or a
thermoset material. The ring-shaped elements may include plastic
rings, metallic rings, un-reinforced plastic rings and/or metal
reinforced plastic rings assembled along the length of the tubular
structure to provide variable flexibility and kink-resistance. The
tubular structure may have a cross-section of any geometric shape
and it may be bent, twisted or curved without kinking. The
ring-shaped elements may have different flexural modulus. The
ring-shaped elements may include a combination of flexible and
rigid ring-shaped elements assembled along different portions or
sections of the tubular structure. The ring-shaped elements may be
metallic and may be bonded with a resilient, flexible elastomeric
adhesive, wherein the ring-shaped elements may have different
lengths and may be fused closer or further apart to one another
depending on the characteristics of a portion or section of the
tubing. In another aspect of the invention, the medical tubing may
further comprise a secondary lumen and a pull wire to control the
tubular structure. The ring-shaped elements may be truncated to
provide a bending bias. In another aspect of the invention, the
ring-shaped elements may vary in diameter and/or composition in
different portions or sections of the tubular structure. In yet
another aspect of the invention, some of the ring-shaped elements
may be radiopaque, or the ring-shaped elements may comprise of
different colors to operate as indicators along the tubular
structure.
Inventors: |
Brustad, John R.; (Dana
Point, CA) ; Hilal, Said S.; (Coto De Caza, CA)
; Hilal, Nabil; (Laguna Niguel, CA) ; Hart,
Charles C.; (Summerville, SC) ; Johnson, Gary M.;
(Mission Viejo, CA) ; Hilal, Serene; (Rancho Santa
Margarita, CA) ; Sakakine, Ghassan; (Mission Viejo,
CA) ; Gadberry, Donald L.; (San Juan Capistrano,
CA) ; Pingleton, Edward D.; (Laguna Niguel, CA)
; Petrime, Matthew N.; (Los Angeles, CA) ;
Adlparvar, Payam; (Lake Forest, CA) ; Hadley, Carl
B.; (Foothill Ranch, CA) ; Vu, Kenneth K.;
(Ladera Ranch, CA) |
Correspondence
Address: |
APPLIED MEDICAL RESOUCES CORPORATION
22872 Avenida Empresa
Rancho Santa Margarita
CA
92688
US
|
Family ID: |
34795602 |
Appl. No.: |
10/766138 |
Filed: |
January 28, 2004 |
Current U.S.
Class: |
604/264 ;
138/118 |
Current CPC
Class: |
A61M 25/0043 20130101;
A61M 2025/0034 20130101; A61B 1/0055 20130101; A61B 2017/003
20130101; A61B 1/0011 20130101; A61M 25/0012 20130101; A61M
2039/082 20130101; A61B 17/3421 20130101; A61M 2025/0037
20130101 |
Class at
Publication: |
604/264 ;
138/118 |
International
Class: |
A61M 005/00 |
Claims
1. A medical tubing adapted for insertion into a body tissue or
cavity having a length with variable characteristics, comprising: a
plurality of individual, discrete, generally ring-shaped elements
arranged in series and fused or bonded together forming a
continuous tubular structure.
2. The medical tubing of claim 1, wherein the ring-shaped elements
are formed of a thermoplastic material.
3. The medical tubing of claim 1, wherein the ring-shaped elements
are formed of a thermoset material.
4. The medical tubing of claim 1, wherein the ring-shaped elements
include at least one of plastic rings, metallic rings,
un-reinforced plastic rings and metal reinforced plastic rings
assembled along the length of the tubular structure to provide
variable flexibility and kink-resistance.
5. The medical tubing of claim 1, wherein the tubular structure may
be bent, twisted or curved without kinking.
6. The medical tubing of claim 1, wherein the tubular structure has
a cross-structure including circular, oval, rectangular,
triangular, hexagonal and any geometric shape.
7. The medical tubing of claim 1, wherein the ring-shaped elements
have different flexural modulus.
8. The medical tubing of claim 1, wherein the ring-shaped elements
include a combination of flexible and rigid ring-shaped elements
assembled along different portions or sections of the tubular
structure.
9. The medical tubing of claim 4, wherein the metallic rings are
coated with plastic and are assembled with alternating elastomeric
rings.
10. The medical tubing of claim 8, wherein as the tubular structure
is bent, twisted or curved, the rigid ring-shaped elements provide
reinforcement to maintain the size and shape of the lumen and the
flexible ring-shaped elements operate to stretch and compress to
prevent kinking.
11. The medical tubing of claim 1, wherein the ring-shaped elements
are metallic and are bonded with a resilient, flexible elastomeric
adhesive.
12. The medical tubing of claim 11, wherein the ring-shaped
elements have different lengths and are fused closer or further
apart to one another depending on the characteristics of a portion
or section of the tubing.
13. The medical tubing of claim 1, further comprising a secondary
lumen and a pull wire to control the tubular structure.
14. The medical tubing of claim 1, wherein at least one of the
ring-shaped elements is truncated to provide a bending bias.
15. The medical tubing of claim 14, wherein the truncated elements
comprise of alternating flexible ring-shaped elements and rigid
ring-shaped elements.
16. The medical tubing of claim 1, wherein the ring-shaped elements
vary in diameter in different portions or sections of the tubular
structure.
17. The medical tubing of claim 16, wherein the composition of the
ring-shaped elements vary in the different portions or sections of
the tubular structure.
18. The medical tubing of claim 17, wherein the ring-shaped
elements are assembled in accordance with a preferred modulus
within portions or sections of the tubular structure.
19. The medical tubing of claim 1, wherein at least one of the
ring-shaped elements is radiopaque.
20. The medical tubing of claim 1, wherein the ring-shaped elements
comprise of different colors to operate as indicators along the
tubular structure
21. A method of manufacturing a medical tubing having a length with
variable characteristics, the medical tubing comprising a plurality
of individual, discrete, generally ring-shaped elements arranged in
series and fused together to form a continuous tubular structure,
the method comprising the steps of: placing the plurality of
ring-shaped elements upon a support member or mandrel in a series
arrangement; and heating the plurality of ring-shaped elements to
fuse them together over the support member or mandrel
22. The method of claim 21, further comprising placing the
plurality of ring-shaped elements upon a second support member or
mandrel before the heating step to subsequently form a second lumen
or control tube to the tubular structure.
23. The method of claim 21, further comprising forming a control
tube over the assembled ring-shaped elements prior to the heating
step.
24. The method of claim 23, wherein the control tube comprises at
least one of glass, silicone, heat shrinkable polyolefin, PTFE,
FEP, metallic or other tubing that has a higher melting temperature
than the assembled ring-shaped elements.
25. A method of manufacturing a medical tubing having a length with
variable characteristics, the medical tubing comprising a plurality
of individual, discrete, generally ring-shaped elements arranged in
series and fused together to form a continuous tubular structure,
the method comprising the steps of: placing the plurality of
ring-shaped elements upon a support member or mandrel in a series
arrangement; and fusing the plurality of ring-shaped elements
together over the support member or mandrel with a solvent or other
chemical compound.
26. The method of claim 25, wherein the fusing step further
comprises immersing the ring-shaped elements into the solvent to
fuse the elements
27. A method of manufacturing a medical tubing having a length with
variable characteristics, the medical tubing comprising a plurality
of individual, discrete, generally ring-shaped elements arranged in
series and bonded together to form a continuous tubular structure,
the method comprising the steps of: placing the plurality of
ring-shaped elements upon a support member or mandrel in a series
arrangement; and bonding together the plurality of ring-shaped
elements upon a support member or mandrel with an adhesive.
28. The method of claim 27, wherein the adhesive is photodynamic or
heat-activated.
29. The method of claim 21, further comprising coating the tubular
structure with an elastomeric adhesive or dispersion.
30. The method of claim 21, wherein the mandrel has a pre-formed
curvature for accessing a specific region of a body cavity.
31. The method of claim 21, wherein the mandrel includes a
collapsible, inflatable or dissolvable mandrel allowing the tubular
structure to vary in diameter and lumen size.
32. The method of claim 31, wherein the mandrel is formed of an
electrically dissolvable epoxy resin.
33. The medical tubing of claim 1, wherein the tubing is used as an
AV introducer, a urological sheath, a ureteral access sheath, a
urethral and bladder access sheath, a kidney access sheath, a
ureteral stent, a trocar cannula, a suction/irrigation tubing, an
insufflation tubing, a vacuum tubing, a split sheath introducer, a
tracheostomy tube, an intubation tube, a gastronomy tube, a
jujenostomy tube, an extracorporeal retrograde
cholangeopancreatography catheter, an endoscope shaft, a drainage
tube, a guide catheter, a hydrocephalic shunt, a guidewire, an
angioplasty and dilation balloon, a vascular graft, a
cholangiography catheter, a vascular embolectomy/thrombectomy
catheter, or a central venous catheter.
34. A method of manufacturing a thin-walled tube, comprising:
coating a wire with a plastic material; wrapping the coated wire
around a mandrel forming a plurality of windings; and heating the
wound coated wire until the plastic material melts and bonds the
windings forming a wire-reinforced tube.
35. The method of claim 34, wherein the plastic material comprises
at least one of polyurethane, a thermoplastic material and a
thermoset material.
36. The method recited of claim 34, wherein the wire comprises at
least one of a metallic material and a second plastic material.
37. The method of claim 34, wherein the wire is coated with the
plastic material in a coextrusion process.
38. The method of claim 34, wherein the tube has a wall thickness
of about 0.015" or less.
39. The method of claim 34, wherein the tube has an inner diameter
that ranges from about 0.026" to about 0.75".
40. The method of claim 39, wherein the tolerance on the inner
diameter is on the order of 0.001" or less.
41. The method of claim 34, further comprising compressing the
windings as the coated wire is being heated
42. The method of claim 34, further comprising providing a mold to
compress the windings.
43. The method of claim 34, further comprising removing the
wire-reinforced tube from the mandrel after the tube is cooled.
44. The method of claim 34, wherein the wound coated tube is heated
until the plastic material is formed above, below and between all
the windings.
45. The method of claim 34, further comprising dipping the tube in
a solvent based solution forming an outer layer of the tube.
46. The method of claim 34, wherein the mandrel is tapered to
provide the tube with varying diameter throughout the length of the
tube.
47. The method of claim 34, further comprising providing a filament
comprising a material different from the coating of the wire.
48. The method of claim 47, wherein the coated wire is
alternatively wound with the filament around the mandrel.
49. The method of claim 34, wherein the mandrel may be any shape
such that the resultant shape of the tube can be removed from the
mandrel after the heating step.
50. The method of claim 49, wherein the mandrel is a multiple-part
mandrel.
51. A method of manufacturing a kink-resistant thin-walled tube
having a length with different characteristics, comprising: coating
a mandrel with a first layer of plastic material; placing a spring
reinforcement over the first layer; and coating the spring
reinforcement with a second layer of plastic material to form a
spring-reinforced tube.
52. The method of claim 51, wherein the first layer is formed in an
extrusion process.
53. The method of claim 51, wherein the first layer is formed in a
molding process.
54. The method of claim 51, wherein the second layer is formed in
an extrusion process.
55. The method of claim 51, wherein the second layer is formed in a
molding process.
56. The method of claim 51, wherein the spring reinforcement is a
pre-wound wire comprising at least one of a metallic material and a
second plastic material.
57. The method of claim 51, wherein the spring reinforcement is a
wire comprising at least one of a metallic material and a second
plastic material wound around the first layer.
58. The method of claim 51, further comprising dipping the tube in
a solvent based solution forming an outer layer of the tube.
59. The method of claim 51, wherein the mandrel is tapered to
provide the tube with varying diameter throughout the length of the
tube.
60. The method of claim 51, wherein the mandrel may be any shape
such that the resultant shape of the tube can be removed from the
mandrel.
61. The method of claim 60, wherein the mandrel is a multiple-part
mandrel.
62. A method of manufacturing a kink-resistant thin-walled tube
having a length with different characteristics, comprising: coating
a mandrel with a first layer of plastic material; placing a spring
reinforcement over the first layer; and dipping the
spring-reinforced first layer in a solvent based solution to form a
second layer of the tube.
63. The method of claim 62, wherein the second layer is
impervious.
64. The method of claim 62, wherein the mandrel is tapered to
provide the tube with varying diameter throughout the length of the
tube.
65. The method of claim 62, wherein the mandrel may be any shape
such that the resultant shape of the tube can be removed from the
mandrel.
66. The method of claim 65, wherein the mandrel is a multiple-part
mandrel.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention generally relates to medical devices and,
more specifically, to medical tubing adapted for insertion into a
body tissue or cavity having variable characteristics and method of
making same.
[0003] 2. Discussion of Related Art
[0004] Medical tubing includes tubing used as catheters, drain
tubes, access ports, endoscope bodies and the like. The
requirements for each type of medical tubing will depend on its
use. In particular, a specific length of medical tubing may vary
depending on each application. For example, a specific length of
medical tubing may need to be very flexible and yet pushable, or it
may need to be thin-walled and yet kink-resistant. In addition, the
tubing may need to exhibit these properties in only specific
regions.
[0005] Most medical tubing is extruded from a single plastic
material in a continuous forming process. Certain characteristics
or variations may be imparted to the extruded tubing by altering
the speed or the tension of the extruded material as it exits and
cools from the extrusion machine. However, the variations are
limited by the fact that a single material is extruded. Recent
advances in extrusion technology have allowed the co-extrusion of
multiple materials. This provides some usable variations in
extruded tubing. Nevertheless, this is still a linear process and
is still limited by the continuous flow of the extruded
materials.
[0006] Accordingly, there is a need for a medical tubing having a
length with variable characteristics and a method of making the
tubing such that variations can occur along the length of the
manufactured tubing. For instance, a length of the tubing may be
rigid for a length, becomes flexible for a length and then becomes
rigid again for another length. It is also desirable to have large
variations in the diameter of the tubing. In another application,
there may be a need for a tube that is extremely kink-resistant in
a specific region. Kink-resistance with very thin walls is not
obtainable through the current extrusion processes.
SUMMARY OF THE INVENTION
[0007] The invention is primarily directed to a medical tubing
adapted for insertion into a body tissue or cavity and method of
manufacturing different variations of the tubing along a length of
the tubing. In one aspect of the invention, the medical tubing
includes a length with variable characteristics, the tubing
comprising a plurality of individual, discrete, generally
ring-shaped elements arranged in series and fused or bonded
together forming a continuous tubular structure. The ring-shaped
elements may be formed of a thermoplastic or a thermoset material.
The ring-shaped elements may include plastic rings, metallic rings,
un-reinforced plastic rings and/or metal reinforced plastic rings
assembled along the length of the tubular structure to provide
variable flexibility and kink-resistance. The tubular structure may
be bent, twisted or curved without kinking. The tubular structure
may have a cross-section that is circular, oval, rectangular,
triangular, hexagonal or any geometric shape. The ring-shaped
elements may have different flexural modulus. The ring-shaped
elements may include a combination of flexible and rigid
ring-shaped elements assembled along different portions or sections
of the tubular structure, wherein as the tubular structure is bent,
twisted or curved, the rigid ring-shaped elements provide
reinforcement to maintain the size and shape of the lumen and the
flexible ring-shaped elements operate to stretch and compress to
prevent kinking. The ring-shaped elements may be metallic and may
be bonded with a resilient, flexible elastomeric adhesive, wherein
the ring-shaped elements may have different lengths and may be
fused closer or further apart to one another depending on the
characteristics of a portion or section of the tubing.
[0008] In another aspect of the invention, the medical tubing may
further comprise a secondary lumen and a pull wire to control the
tubular structure. It is appreciated that at least one of the
ring-shaped elements may be truncated to provide a bending bias.
The truncated elements may comprise of alternating flexible
ring-shaped elements and rigid ring-shaped elements. In yet another
aspect of the invention, the ring-shaped elements may vary in
diameter and/or composition in different portions or sections of
the tubular structure. In another aspect of the invention, some of
the ring-shaped elements may be radiopaque, or the ring-shaped
elements may comprise of different colors to operate as indicators
along the tubular structure. Applications of the medical tubing of
the invention include AV introducers, urological sheaths, ureteral
access sheaths, urethral and bladder access sheaths, kidney access
sheaths, ureteral stents, trocar cannulas, suction/irrigation
tubing, insufflation tubing, vacuum tubing, split sheath
introducers, tracheostomy tubes, intubation tubes, gastronomy
tubes, jujenostomy tubes, extracorporeal retrograde
cholangeopancreatography catheters, endoscope shafts, drainage
tubes, guide catheters, hydrocephalic shunts, guidewires,
angioplasty and dilation balloons, vascular grafts, cholangiography
catheters, vascular embolectomy/thrombectomy catheters, and central
venous catheters.
[0009] In another aspect of the invention, a method of
manufacturing the medical tubing having a length with variable
characteristics is disclosed, the method comprising the steps of
placing a plurality of ring-shaped elements upon a support member
or mandrel in a series arrangement, and heating the plurality of
ring-shaped elements to fuse them together over the support member
or mandrel. The method of the invention may further comprise the
step of placing the plurality of ring-shaped elements upon a second
support member or mandrel before the heating step to subsequently
form a second lumen or control tube to the tubular structure. This
method may further comprise the step of forming a control tube over
the assembled ring-shaped elements prior to the heating step. The
control tube may comprise at least one of glass, silicone, heat
shrinkable polyolefin, PTFE, FEP, metallic or other tubing that has
a higher melting temperature than the assembled ring-shaped
elements. This method may further comprise the step of coating the
tubular structure with an elastomeric adhesive or dispersion. In
another aspect of the invention, the mandrel may have a pre-formed
curvature for accessing a specific region of a body cavity, the
mandrel may include a collapsible, inflatable or dissolvable
mandrel allowing the tubular structure to vary in diameter and
lumen size, and the mandrel may be formed of an electrically
dissolvable epoxy resin.
[0010] In another aspect of the invention, a method of
manufacturing a medical tubing having a length with variable
characteristics is disclosed, the method comprising the steps of
placing a plurality of ring-shaped elements upon a support member
or mandrel in a series arrangement, and fusing the plurality of
ring-shaped elements together over the support member or mandrel
with a solvent or other chemical compound. In this method of the
invention, the fusing step may further comprise the step of
immersing the ring-shaped elements into the solvent to fuse the
elements.
[0011] In another aspect of the invention, a method of
manufacturing a medical tubing having a length with variable
characteristics is disclosed, the method comprising the steps of
placing a plurality of ring-shaped elements upon a support member
or mandrel in a series arrangement, and bonding together the
plurality of ring-shaped elements upon a support member or mandrel
with an adhesive. The adhesive may be photodynamic or
heat-activated.
[0012] In another aspect of the invention, a method of
manufacturing a thin-walled tube is disclosed comprising the steps
of coating a wire with a plastic material, wrapping the coated wire
around a mandrel forming a plurality of windings, and heating the
wound coated wire until the plastic material melts and bonds the
windings forming a wire-reinforced tube. In this method of the
invention, the plastic material may comprise at least one of
polyurethane, a thermoplastic material and a thermoset material. In
another aspect of the invention, the wire may comprise at least one
of a metallic material and a second plastic material, or the wire
may be coated with the plastic material in a coextrusion process.
This method of the invention may further comprise the step of
compressing the windings as the coated wire is being heated.
[0013] In another aspect of the invention, this method may further
comprise the step of providing a mold to compress the windings.
This method may further comprise the step of removing the
wire-reinforced tube from the mandrel after the tube is cooled. The
wound-coated tube may also be heated until the plastic material is
formed above, below and between all the windings. This method may
further comprise the step of dipping the tube in a solvent-based
solution forming an outer layer of the tube. In other aspects of
the invention, the mandrel may be tapered to provide the tube with
varying diameter throughout the length of the tube, the coated wire
may be alternatively wound with the filament around the mandrel,
the mandrel may be any shape such that the resultant shape of the
tube may be removed from the mandrel after the heating step, and
the mandrel may be a multiple-part mandrel.
[0014] In another aspect of the invention, a method of
manufacturing a kink-resistant thin-walled tube having a length
with different characteristics is disclosed, the method comprising
the steps of coating a mandrel with a first layer of plastic
material, placing a spring reinforcement over the first layer, and
coating the spring reinforcement with a second layer of plastic
material to form a spring-reinforced tube. In this method of the
invention, each of the first layer and the second layer may be
formed in either an extrusion process or a molding process. The
spring reinforcement of the invention may be a pre-wound wire
comprising at least one of a metallic material and a second plastic
material. The method of the invention may further comprise the step
of dipping the tube in a solvent-based solution forming an outer
layer of the tube.
[0015] In another aspect of the invention, another method of
manufacturing a kink-resistant thin-walled tube having a length
with different characteristics is disclosed, the method comprising
the steps of coating a mandrel with a first layer of plastic
material, placing a spring reinforcement over the first layer, and
dipping the spring-reinforced first layer in a solvent based
solution to form a second layer of the tube. In this method of the
invention, the second layer is impervious, the mandrel may be
tapered to provide the tube with varying diameter throughout the
length of the tube, and the mandrel may be any shape such that the
resultant shape of the tube may be removed from the mandrel.
DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a perspective view of a length of medical
tubing according to a first embodiment of the invention;
[0017] FIG. 2 illustrates a perspective view of a single plastic
ring of the tubing of the invention to be arranged in a series;
[0018] FIG. 3 illustrates a perspective view of the medical tubing
of the invention being formed according to a process of the
invention;
[0019] FIG. 4 is a side view of a composite tube of the invention
in a straight condition;
[0020] FIG. 5 is a side view of the composite tube of FIG. 4 in a
bent condition;
[0021] FIG. 6 is an end view of the composite tube of FIG. 4;
[0022] FIG. 7 is a side view of a tube having a bending bias in
accordance with another embodiment of the invention;
[0023] FIG. 8 is an end view of the tube of FIG. 7 having a bending
bias;
[0024] FIG. 9 is a side view of a wire-ring reinforced tube in a
straight condition in accordance with another embodiment of the
invention;
[0025] FIG. 10 is a side view of the wire-ring reinforced tube of
FIG. 9 in a bent or circular condition;
[0026] FIG. 11 is an end view of the wire-ring reinforced tube of
FIG. 9; and
[0027] FIGS. 12(a) and 12(b) illustrate perspective views of tubes
having varying diameters in accordance with additional embodiments
of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE
INVENTION
[0028] A medical tubing is illustrated in FIG. 1 and is designated
by reference numeral 10. The medical tubing 10 is adapted for
insertion into a body tissue or cavity. The tubing 10 has a
proximal end 12, a distal end 14, a length and at least one lumen
15. The tubing 10 is constructed of a plurality of individual,
discrete, generally ring-shaped elements 16 arranged in series to
form a continuous tubular structure 18. FIG. 2 illustrates a
perspective view of a single generally ring-shaped plastic ring 16
of the tubing 10 of the invention to be arranged in a series. In
one aspect of the invention, the ring-shaped elements 16 are formed
of a thermoplastic material. In another aspect of the invention,
the ring-shaped elements 16 are formed of a thermoset material. The
ring-shaped elements 16 may be arranged in series and subsequently
fused or bonded by heat or chemical reaction to form a
substantially continuous form.
[0029] Referring to FIG. 5, it can be seen that tubing constructed
from a series of individual, discreet elements may be bent, shaped
or coiled without kinking. In particular, the tubing 10 may have
variable characteristics along the length. This may be achieved,
for example, by the use of the ring-shaped elements 16 to provide
different flexural modulus. For instance, a length of tubing may be
constructed wherein flexible ring-shaped elements are separated by
rigid ring-shaped elements, i.e., a flexible portion of a tubular
structure may be formed adjacent to a rigid or semi-rigid portion
of the tubular structure to provide variable flexibility. Such
construction allows softer, more flexible material to be displaced
and stretched along a curvature so that the rigid material is not
deformed. A preferred embodiment may comprise a thermoplastic of a
very rigid nature spaced by a compatible thermoplastic of a very
soft nature. In other words, the ring-shaped elements 16 may be
formed of two or more different materials having different chemical
composition and hardness that are alternately fused or bonded
together to form a continuous tube having circumferential portions
that are alternately rigid and flexible.
[0030] Referring back to FIG. 3, there is shown a process of
manufacturing the medical tubing 10 having variable characteristics
of the invention where a support member or mandrel 20 is used to
hold an assembly of ring-shaped elements 16 in an elongate, series
arrangement. In particular, the process of manufacturing the
medical tubing 10 comprises the steps of placing the plurality of
ring-shaped elements 16 upon the support member or mandrel 20 in a
series arrangement; and heating the plurality of ring-shaped
elements 16 to fuse them together over the support member or
mandrel 20. Additional lumens may be incorporated into the formed
tubular structure 18 and supporting them with, e.g., an elongate
wire. The arranged or assembled ring-shaped elements 16 are then
heated so that the ring-shaped elements 16 are fused together over
the mandrel(s) 20.
[0031] In another aspect of the invention, it is contemplated that
a control tube is placed over the arranged or assembled ring-shaped
elements 16 prior to the application of heat. The control tube may
comprise of glass, silicone, heat shrinkable polyolefin, PTFE, FEP,
metallic or other tubing that has a higher melting temperature than
the assembled ring-shaped elements 16. A silicone control tube may
be placed over the assembled ring-shaped elements 16 as the control
tube and the assembled ring-shaped elements 16 are placed in an
oven until the plastic ring-shaped elements 16 have fused together.
Alternatively, the mandrel 20 may be heated until the thermoplastic
ring-shaped elements 16 have fused together. The control tube and
the mandrel(s) 20 are subsequently removed from the tubing 10.
[0032] In another aspect of the invention, the ring-shaped elements
16 could have either an inner diameter or an outer diameter or a
combination of both comprising of thermoplastic or applied
thermoset material along with the mandrel 20. A compression sleeve
of silicone tubing could be placed over the structure and either
heated or allowed to cure. The resulting product once the
compression sleeve is removed would be very flexible and malleable
and yet would have tremendous column strength. This structure and
variants thereof would be applicable, e.g., to the malleable shaft
graspers. In another aspect, the nested springs could be replaced
with U-joints of various types.
[0033] Alternatively, the process of the invention could be
accomplished with a thermoset material as follows. The spring wire
is wound on the mandrel with the desired pitch. It is then coated
in the thermoset such as silicone. Next, the silicone compression
tube is placed over the spring wire and the assembly is allowed to
cure. The tube is then removed from the silicone tube and mandrel.
Springs can be pre-wound and can be made of materials other than
steel that would otherwise not tolerate the heat required to flow a
thermoplastic.
[0034] In another aspect of the invention, the entire process can
be accomplished in the opposite manner to achieve the same results.
This may be done by pre-winding a co-extruded wire into a spring
and inserting it into a tube of desired diameter. A balloon or
other such mechanism for pressurizing the spring coil may be
inserted as the mandrel in the I.D. and the assembly are heated. As
a result, the compression member is on the inside and the static
member is on the outside.
[0035] It is appreciated that coating the mandrels with various
types of low friction surfaces assist in the removal of the
finished tube. For example, Teflon coatings and various mold
releases have been found to be effective.
[0036] Multiple lumens can also be easily included in the fusing or
bonding process of the invention. This can be accomplished in
numerous ways. The first is to provide a groove in the winding
mandrel and place a stainless tube in the groove. The winding
extrusion is placed on the mandrel as before. When the resulting
assembly is removed, the stainless tube will be imbedded in the
plastic of the wire extrusion. Another way to accomplish multiple
lumens is to wind separate mandrels with the wire extrusion and
then instead of placing the silicone compression sleeve around each
mandrel individually the mandrel assemblies are placed next to each
other and the compression sleeve is placed over both of them.
Mandrels can be of a variety of shapes to give the lumens of the
resulting tube different internal and external shapes. Another
version of this concept would be to assemble the mandrels with a
strip or extrusion of plastic material (or non-plastic may work as
well) in between the mandrels and then the assembled mandrels can
have the extruded wire wound around them. The assembly would then
be fused or bonded and the plastic in between the mandrels would
form very thin walled lumens.
[0037] As such, it is appreciated that lumens can be placed
external or internal to the main lumen of a catheter. Tremendous
advantages in overall size of the catheters can be achieved because
unlike conventional extrusion techniques which require that wall
thickness be maintained constant, the catheters of the invention
can have wall thickness not only of localized thickness increases
but also lengths or sections of different materials.
[0038] The tubing constructed according to the present invention is
especially unique in that it may be constructed having an extremely
thin wall section. FIGS. 1-6 illustrate a relationship between a
diameter of a tube and a wall thickness of that tube. Normally,
tubing having a large diameter (0.200" or larger) and a very thin
wall (0.015" or less) is extremely subject to kinking when it is
bent, coiled or twisted. However, tubing constructed according to
the present invention does not kink under the same circumstances
since the softer materials allow bending without deformation of the
primary, rigid material. It can be seen that as the tubing is bent,
shaped or curved, the rigid material acts as a reinforcement to
maintain the size and shape of the lumen whereas the soft material
stretches along the large arc and compresses along the short arc.
The stresses that normally accumulate along a thin walled tube and
cause it to kink are absorbed and distributed in the composite
construction of the present invention so that the tubing does not
kink. Kink-free tubing may be constructed having wall thickness to
diameter ratios in excess of 20:1, which in a standard extrusion is
not possible. Wire coil reinforced tubing allows tubing to be made
with a very thin wall. High diameter to wall ratios are possible
when a wire coil is used to reinforce an extruded tube. However,
wire reinforcement creates hysterisis and makes the formation of
additional lumens problematic. In addition, it requires that
formation of the tubing be done in a continuous form, not allowing
for variations at specific regions along the length of the
tubing.
[0039] In another embodiment of the invention, a method of
manufacturing the medical tubing 10 having variable characteristics
is disclosed, the method comprising the steps of placing the
plurality of ring-shaped elements 16 upon the support member or
mandrel 20 in a series arrangement; and fusing the plurality of
ring-shaped elements 16 together over the support member or mandrel
20 with a solvent or other chemical compound. That is, this
embodiment contemplates the use of solvent materials to fuse the
various ring-shaped elements 16 together to form the continuous
tubular structure 18. The ring-shaped elements 16 may be arranged
or assembled upon the support member or mandrel 20 in a desired
sequence for specific applications. Then, a solvent may be applied
to the assembled elements so that they are fused together to form a
continuous length of tubing. In another aspect of the invention,
the assembled elements 16 may be immersed into a solvent to fuse
the elements.
[0040] In yet another embodiment of the invention, an adhesive may
be used to adhere the various ring-shaped elements 16 together to
form the continuous tubular structure 18. For instance, a
heat-activated adhesive may be formed as a ring-shaped element and
placed between each of the rigid and flexible ring-shaped elements
16. When heat is applied, the adhesive is activated and the
ring-shaped elements 16 are bonded. In another aspect, a
photodynamic adhesive may be used to bond the ring-shaped elements
16. Such adhesives include epoxies that are cured by application of
UV light. Other adhesives, such as cyanoacrylates and various
rubber cements may be used to achieve specific results. Another
aspect of the invention contemplates the use of a highly resilient,
flexible rubber-like adhesive, such as silicone or other
elastomeric adhesive, to bond the rigid ring-shaped elements 16
together. Such a construction allows the bond to absorb and
distribute the forces that would normally kink a large-diameter,
thin-walled tube and maintain the shape of the lumen. For instance,
a series of rigid ring-shaped elements may be loosely assembled
upon a mandrel or form and subsequently coated with an elastomeric
adhesive or dispersion. The elastomeric adhesive material that
flows between the rigid ring-shaped elements forms a resilient,
flexible region between the rigid elements. An alternate embodiment
contemplates the use of metallic rings assembled upon a mandrel and
subsequently bonded together with a resilient, flexible elastomeric
adhesive. The bending characteristics of such a construction may be
imparted by varying the length of the metallic ring-shaped
elements. For instance, a semi-rigid portion may be comprised of
metallic ring-shaped elements that are long in comparison to the
metallic ring-shaped elements of a flexible portion. The metallic
ring-shaped elements of the flexible portion are shorter allowing a
tighter or smaller bending radius.
[0041] The tubing and process of manufacturing of the tubing of the
invention provide a distinct advantage over extrusion in that a
sensitive flexible portion may be reinforced while less sensitive
regions may be left alone or un-reinforced. Additionally, there are
many medical applications where only a portion of the tubing should
be flexible while other portions should be rigid or semi-rigid.
There are also applications where a portion must be very soft and
flexible but must also be non-compressible and kink-free and yet
have a portion rigid enough to allow navigation through tortuous
lumens. An example of conflicting requirements include endoscope
shafts, urinary, billiary and vascular catheters as further
described below. Many of these devices could benefit from a
thin-walled tube that has a large primary lumen, one or more
secondary lumens and a very flexible portion that may be controlled
by pull wire(s) or cable(s) within the secondary lumen(s).
[0042] Referring to FIG. 7, there is shown a length of tubing 30
according to another embodiment of the invention having alternating
ring-shaped elements 32 that are shaped to provide a preferred
bending bias 36. In this embodiment, the more rigid ring-shaped
elements 32a are truncated or wedge-shaped, as are the less rigid
elements 32b. A preferred arrangement of alternating truncated or
wedge-shaped elements 32a and 32b provides the preferred bending
bias 36. Stated another way, the larger flexible portion adjacent
to the smaller rigid portion and is opposed to the smaller flexible
portion adjacent to the larger rigid portion provides a bias toward
the side having the larger flexible portion when a compression load
is applied. The opposite is the case when a tension load is
applied. As can be seen from the figures, the biasing arrangement
may be formed adjacent to a rigid or semi-rigid arrangement of
discreet, individual ring-shaped elements. FIG. 8 illustrates an
end view of the tube having the bending bias of FIG. 7. FIGS. 9 and
10 are side views of a wire-ring reinforced tube in a straight and
in a bent condition, respectively, in accordance with another
embodiment of the invention, and FIG. 11 is an end view of the
wire-ring reinforced tube of FIG. 9.
[0043] Referring to FIG. 12, a length of tubing 40 is shown having
a first diameter 42 and at least a second diameter 44. The
differing diameters are a product of assembling various ring-shaped
elements 46 upon a forming mandrel and fusing the elements 46
together to form a continuous tube. It can be seen that many
different arrangements of smaller, larger, softer and harder
materials may be assembled in any number of ways. In addition,
various colored elements may be arranged as indicators or
radiopaque elements may be assembled along the length of the
assembled tube. For example, a rigid portion of tubing may be
produced for a specific length at a specific diameter, followed by
a semi-rigid portion at a second diameter (smaller or larger),
followed by a very flexible portion at a third diameter (smaller or
larger), followed by a rigid or semi-rigid portion at a fourth
diameter (smaller or larger) and so on.
[0044] The present invention also contemplates the use of mandrels
or forms that may have curves or other useful forms or shapes that
fit various uses. For instance, guiding catheters may be
constructed that have pre-formed curvatures for accessing specific
anatomical regions of a body. Mandrels or forms may include
collapsible, inflatable, dissolvable or the like that allow the
tubular body to have variations in diameter and lumen size. As an
example, a mandrel or form may be constructed of an electrically
dissolvable epoxy resin. The mandrel or form retains its shape
until an electrical impulse is applied. The material separates upon
application of electrical energy leaving a complex lumen shape
within the tubular body.
[0045] The following is yet another example of a process for making
thin-walled tubes of the invention:
[0046] (1) First, a mandrel of steel is machined to match the
internal diameter or shape of the intended tube;
[0047] (2) Second, a stainless steel wire, e.g., of about 0.006" in
diameter has a layer of polyurethane co-extruded onto it with a
resulting diameter of about 0.020";
[0048] (3) The co-extruded wire is close wound around the length of
the mandrel and the ends are secured such that the resultant coil
will not unwind;
[0049] (4) Fourth, a silicone tube with an inner diameter (I.D.)
less than that of the wound coil outer diameter (O.D.) is placed
over the entire assembly such that it completely covers the wound
coil;
[0050] (5) Fifth, the assembly is placed in an oven at
approximately 180.degree. C. for 15 to 30 minutes (this is for
Pellethane; other plastics require different parameters.);
[0051] (6) Sixth, the assembly is removed from the oven and cooled.
The silicone sheath is removed once the assembly has cooled;
and
[0052] (7) Seventh, the wound coil is removed from the mandrel.
[0053] This process results in a tube with walls of about 0.015" in
thickness and a reinforced coil of stainless wire embedded in it.
The tube is virtually un-kinkable and has very smooth inner and
outer diameter surfaces. In addition, the mandrel can be tapered to
provide a tube with variable diameters from one end to the other.
In other examples, physical properties of the resulting tube can be
adjusted by varying the diameter of the wire, the diameter of the
co-extruded plastic, the type and properties of the wire and
plastic such as chemical composition and hardness. The tolerance
that can be held on the I.D. of the tube is very high and on the
order of 0.001" or less. The tolerance on the O.D. is comparable.
The range of diameters for this process is quite large. Prototypes
have been made from 0.026" I.D. to 0.75" I.D. and with wires from
0.004" diameter to 0.008" inch diameter.
[0054] It should be noted that two or more different types of
wire/plastic extrusions can be wound together and the wire is not a
requirement for this process to work. This process would be useful
for molding thin wall tubes to dimensions that are not practical or
obtainable by extrusion or traditional molding. Mandrels do not
need to be round and could combine both round and non-round shapes
on the same mandrel.
[0055] The main requirement is that the resultant shape be capable
of being removed from the mandrel once the heat cycle is finished.
With unusual shapes this could be accomplished with split mandrels
and sacrificial mandrels that could be removed by dissolving in
acid by way of example.
[0056] The method of the invention may be applied in the
construction of the following products, at least in part if not in
whole:
[0057] 1. AV introducers: These devices are used to gain access to
blood vessels. The AV introducers of the prior art are typically
fairly thick walled flouropolymer about 2-3 inches long. The AV
introducers of the invention decrease wall thickness and at the
same time increase kink resistance. Vascular surgeons also use
longer versions of these to access various parts of the vascular
system and then use these sheaths to inject various medicants or
use them as a highway for the introduction and removal of
instruments. These longer versions can be 70 centimeters in length
or more and would benefit tremendously by the increased kink
resistance and flexibility that the AV introducers of the invention
would offer.
[0058] More specifically, the sheath of the invention would be
capable of being coated internally as well as externally with
friction reducing coatings such as hydrophilic coatings as well as
heperanized coatings or other medically beneficial surface
treatment.
[0059] 2. Urological sheaths: Different urological sheaths can be
produced by the methods of the present invention, e.g., ureteral
access sheaths, urethral and bladder access sheaths, and kidney
access sheaths modified to direct a scope for various
procedures.
[0060] 3. Ureteral stents: These can be made with the process of
the invention and would have the benefits of thin walls, high
column strength and tremendous flexibility. The common wisdom in
urology is that thin flexible stents are more comfortable for the
patient but more difficult for the physician to place. Larger more
rigid stents are easier to place but uncomfortable for the patient.
The stent of the invention would be both small and flexible and yet
easy to place due to its inherent column strength.
[0061] 4. Trocar cannula: These can be made to be very thin walled
and yet flexible (or inflexible), and can be very resistant to
kinking or compressing. This may be achieved by the bonding or
fusing process of the invention with a braided structure instead of
a coil. In another aspect, a folded structure could be made that
would allow the cannula sheath to be inserted first followed by the
cannula itself.
[0062] 5. Suction/Irrigation (S/I) tubing: Prior art S/I tubing is
currently made from PVC and is very thick walled to prevent the
tube from kinking or collapsing under vacuum. With the process of
the invention, the following benefits can be achieved--the tubing
would be kink resistant yet have thin walls and therefore be
lightweight, cost would be comparable to PVC without the
environmental concern, thus, it would reduce the overall amount of
plastic used. Currently, S/I tubes have 1 to 2 lbs of PVC tubing in
them. The S/I tubing of the invention would reduce the overall
weight of plastic to approximately {fraction (1/10)} of a pound and
would be easier for the surgeon to use. In addition, the wire in
the irrigation tube could be electrically heated to allow the fluid
to be at or near body temperature when introduced to the
patient.
[0063] 6. Insufflation tubing: This tubing is used to deliver
carbon dioxide gas for laparoscopic surgery and has some of the
same problems as S/I tubing. Lighter weight and less plastic
wasteful tubing could be made, and the heating element in the wall
would be of benefit to the patient by allowing body temperature gas
to be introduced instead of colder gas.
[0064] 7. Vacuum tube: The process of the invention would be
beneficial to any situation, either medical or non-medical, where
the need exists for a vacuum tube to be thin walled and preferably
kink resistant. This process could also be used to produce thin
walled pressure tubes.
[0065] 8. Split sheath introducers: The process of the invention
can be modified to make a split sheath introducer. The wire
extrusion can be wound on a special mandrel to make a semicircular
tube on each side of the mandrel and then fusing or bonding the
split sheath together.
[0066] 9. Tracheostomy tubes: Thin walled kink-free tracheostomy
tubes would benefit from the process of the invention. The
balloon-filled lumen could be easily fused or bonded together along
with the breathing tube. The same advantages would apply to
crycothyrodectomy tubes used in emergency situations.
[0067] 10. Intubation tubes: The intubation tubes have very thin
walls and are very kink resistant which would help enormously with
these devices especially in pediatrics or cases where the trachea
has become constricted. The flexibility would make them ideal for
nasal tubes as well.
[0068] 11. G-tubes/J-tubes: Gastronomy and jujenostomy tubes are
used for enteral feeding and would likewise benefit from reduced
diameters, enhanced column strength for insertion, and kink
resistance for safety.
[0069] 12. ERCP catheters: Extracoporeal retrograde
cholangeopancreatography catheters are very long catheters
typically used to treat gallstones in the cystic duct. These would
benefit from the increased column strength and reduced wall
thickness as well as high kink resistance.
[0070] 13. Endoscope shafts: Flexible and steerable endoscopes
require shafts that can give good protection to the internal
components as well as provide regions of variable flexibility and
good column stiffness throughout. The shafts must also accommodate
multiple lumens.
[0071] 14. Drainage tubes: Drainage and suction tubes would also
benefit from thin walls, lightweight and kink resistance.
[0072] 15. Guide catheters: Guide catheters commonly used in
cardiology to gain access to the coronary arteries are carefully
designed to meet various design criteria such as shape, stiffness,
steerability, torque strength and kink resistance. They have to be
smooth and non-thrombogenic. The bonding and fusing process of the
invention can serve as a good basis of construction for these
devices. Torque strength or torqability can be improved in devices
of the invention by putting relatively stiff elements along the
length of the shaft or by altering the plastic used to extrude over
the wire.
[0073] 16. Hydrocephalic shunts: A common problem with these
shunts, which are used to drain excess hydrocephalic fluid from the
ventricles of the brain, is that they can kink and prevent adequate
drainage. This in turn can require a revision to be performed or
merely patient discomfort and possibly increase the chances of an
infection. By producing portions of them with the process of the
invention, it is possible to create very crush as well as kink
resistant shunts.
[0074] 17. Guidewires: Guidewires are used in a number of
applications including urology and radiology. They are commonly
constructed with close wound stainless steel springs and then
coated with Teflon or a plastic for lubricity. They are typically 2
to 6 feet long and are around 1 mm in diameter or less. These
structures can be fabricated with the process of the invention.
[0075] 18. Angioplasty and dilation balloons: The catheters that
these balloons are placed on require the ability to transmit as
much as 15 atmospheres or more over a 3-foot or longer length. Here
again the advantages of reinforced thin walls with excellent column
strength would be very helpful.
[0076] 19. Vascular grafts: A variety of graft designs are commonly
used and these include designs for aortic grafts, dialysis grafts,
bypass grafts, arterial grafts for various locations in the
peripheral vasculature. All of these will benefit from kink
resistance and crush resistance as well as excellent flexibility.
Various coatings and surface modifications can be applied.
[0077] 20. Cholangiography catheters: Catheters used to deliver
contrast media to the cystic duct are difficult to use as the
conflicting requirements of kink resistance and thin walls make
necessary a compromise. This is not the case with the tubing of the
invention where the wall can be kept very thin and kink
resistant.
[0078] 21. Vascular embolectomy/thrombectomy catheters: These small
diameter catheters have balloons on them for removing clots and in
the case of thrombectomy they have a spring body which would make
the process of the invention a natural for them. As for the
embolectomy catheters, they may benefit from the educed profile,
increased inflation lumen and guidewire lumens.
[0079] 22. Central venous catheters: These catheters are placed
near the clavicle and access the superior vena cava through one of
the subclavian or innominate veins. They are used for emergency
treatment in the case of kidney failure among other uses. These
catheters are frequently constructed with two and three lumens and
require the ability to extract and return blood quickly. They would
benefit from the processes of the invention in that the walls can
be made thinner for increased flow or reduced profile or both. They
would be almost kink proof and they would have tremendous column
strength which would aid in insertion. The processes of the
invention would not interfere with any of the commonly used
coatings and they may show up better on ultrasound.
[0080] The foregoing disclosure and description of the invention
are illustrative and explanatory thereof, and various changes in
the size, shape and materials, as well as in the details of the
illustrated construction, may be made without departing from the
spirit and scope of the invention. For these reasons, the above
description should not be construed as limiting the invention, but
should be interpreted as merely exemplary of preferred
embodiments.
* * * * *