AU2013207571B2 - Medical tubing - Google Patents

Abstract

There is disclosed a medical tubing adapted for insertion into a body tissue or cavity having a length with variable characteristics, characterized in comprising: a plurality of individual, discrete, generally ring-shaped elements arranged in series and fused or bonded together forming a continuous tubular structure, and wherein the composition of the ring-shaped elements vary in different portions or sections of the tubular, and wherein the ring-shaped elements are assembled in accordance with a preferred modulus within portions or sections of the tubular structure.

Description

MEDICAL TUBING The content of the complete specification of Australian patent application no. 2005209187 as filed (including the content, if any, incorporated therein by 5 reference) is hereby incorporated herein in its entirety by reference. 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. Medical tubing includes tubing used as catheters, drain tubes, access ports, 10 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. 15 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 20 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. According to a first aspect of the present invention, there is provided 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 25 in series and fused together to form a continuous tubular structure along a longitudinal axis, wherein the composition of the ring-shaped elements vary in different portions of sections of the tubular structure; wherein at least one of the ring-shaped elements is truncated along the longitudinal axis to provide a bending bias; and wherein the ring-shaped elements are assembled in accordance with a preferred flexural modulus within portions or sections of the 30 tubular structure, the method comprising the steps of: placing the plurality of ring-shaped elements upon a support member or a mandrel in a series arrangement; and forming the plurality of ring-shaped elements into a continuous tubular structure. The wire may be coated with the plastic material in a coextrusion process. The 1{ gnulnIorto/ cn\NRPorTI.lDC CGW/51127 41doc' 147/2)1 -2 method may further comprise the step of compressing the windings as the coated wire is being heated. The method may further comprise the step of providing a mold to compress the windings. The method may further comprise the step of removing the wire-reinforced tube 5 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. The method may further comprise the step of dipping the wire-reinforced tube in a solvent-based solution forming an outer layer of the thin-walled tube. The mandrel may be tapered to provide the tube with varying diameter throughout the length of the tube, the mandrel may be any shape 10 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. Each of the first layer and the second layer may be formed in either an extrusion process or a molding process. The method may further comprise the step of dipping the spring-reinforced tube in a solvent-based solution forming an outer layer of the kink-resistant 15 thin-walled tube. Preferred embodiments of the invention provide a tube that is extremely kink-resistant in a specific region. Kink-resistance with very thin walls is not obtainable through prior art extrusion processes. Preferred embodiments of the invention are primarily directed to the manufacture of 20 medical tubing adapted for insertion into a body tissue or cavity. Also disclosed herein is 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 25 coating the spring reinforcement with a second layer of plastic material to form a spring-reinforced tube, wherein the spring reinforcement is a wire, comprising a metallic material and a second plastic material coating the metallic material, wound around the first layer. According to a second aspect of the present invention, there is provided a medical 30 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 along a longitudinal axis, wherein the composition of the ring-shaped elements varies in different portions or sections of the tubular structure, wherein at least one of the ring-shaped elements -2a is truncated along the longitudinal axis to provide a bending bias, and wherein the ring shaped elements are assembled in accordance with a preferred flexural modulus within portions or sections of the tubular structure.. The ring-shaped elements may be formed of a thermoplastic or a thermoset material. The ring-shaped elements may include plastic rings, 5 metallic rings, H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -3 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 5 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 10 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. 15 Also disclosed herein is medical tubing which further comprises 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. The ring-shaped elements may vary in diameter and/or composition in different 20 portions or sections of the tubular structure. 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 25 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 30 venous catheters. Also disclosed herein is a method of manufacturing medical tubing having a length with variable characteristics, 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -4 member or mandrel. The method 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 5 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. The mandrel may have a pre-formed curvature for accessing a specific region 10 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. Also disclosed herein is a method of manufacturing a medical tubing having a length with variable characteristics, the method comprising the steps of placing a plurality 15 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, the fusing step may further comprise the step of immersing the ring-shaped elements into the solvent to fuse the elements. 20 Also disclosed herein is a method of manufacturing a medical tubing having a length with variable characteristics, 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. 25 A method of manufacturing a kink-resistant thin-walled tube having a length with different characteristics is also herein 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 30 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.

H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -5 The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIG. 1 illustrates a perspective view of a length of medical tubing; FIG. 2 illustrates a perspective view of a single plastic ring of the tubing to be 5 arranged in a series; FIG. 3 illustrates a perspective view of the medical tubing being formed according to a particular process; FIG. 4 is a side view of a composite tube in a straight condition; FIG. 5 is a side view of the composite tube of FIG. 4 in a bent condition; 10 FIG. 6 is an end view of the composite tube of FIG. 4; FIG. 7 is a side view of a tube having a bending bias; FIG. 8 is an end view of the tube of FIG. 7 having a bending bias; FIG. 9 is a side view of a wire-ring reinforced tube in a straight condition; FIG. 10 is a side view of the wire-ring reinforced tube of FIG. 9 in a bent or circular 15 condition; FIG. 11 is an end view of the wire-ring reinforced tube of FIG. 9; and FIGS. 12(a) and 12(b) illustrate perspective views of tubes having varying diameters. 20 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 25 perspective view of a single generally ring-shaped plastic ring 16 of the tubing 10 to be arranged in a series. In one example, the ring-shaped elements 16 are formed of a thermoplastic material. In another example, 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 30 continuous form. 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -6 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 5 displaced and stretched along a curvature so that the rigid material is not deformed. A preferred example 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 10 continuous tube having circumferential portions that are alternately rigid and flexible. 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 15 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 20 that the ring-shaped elements 16 are fused together over the mandrel(s) 20. A control tube may be 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 25 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. 30 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -7 have tremendous column strength. This structure and variants thereof would be applicable, e.g., to the malleable shaft graspers. In another example, the nested springs could be replaced with U-joints of various types. Alternatively, the process could be accomplished with a thermoset material as 5 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. 10 In another example, 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 15 static member is on the outside. 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. Multiple lumens can also be easily included in the fusing or bonding process. This 20 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 25 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 30 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. 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -8 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. The tubing may be constructed having an extremely thin wall section. FIGS. 1-6 5 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 preferred embodiments of the present invention does not kink under the same circumstances since the softer materials allow bending without 10 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 tubing so that the 15 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 20 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. In another example, 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 25 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 method 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 30 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. The assembled elements 16 may be immersed into a solvent to fuse the elements. In another example, 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- H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -9 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 example, a photodynamic adhesive may be used to bond the ring-shaped elements 16. Such 5 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 example 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 10 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 15 example 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 20 elements of a flexible portion. The metallic ring-shaped elements of the flexible portion are shorter allowing a tighter or smaller bending radius. The preferred tubing and processes of manufacturing the tubing 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 25 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 30 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). Referring to FIG. 7, there is shown a length of tubing 30 according to another example having alternating ring-shaped elements 32 that are shaped to provide a H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 10 preferred bending bias 36. In this example, 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 5 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 10 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 example, and FIG. 11 is an end view of the wire-ring reinforced tube of FIG. 9. 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 15 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 20 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 semirigid portion at a fourth diameter (smaller or larger) and so on. Also contemplated is the use of mandrels or forms that may have curves or other 25 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 30 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. The following is yet another example of a process for making thin-walled tubes: H:\az,\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 11 (1) First, a mandrel of steel is machined to match the internal diameter or shape of the intended tube; (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"; 5 (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; (4) Fourth, a silicone tube with an inner diameter (1.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; 10 (5) Fifth, the assembly is placed in an oven at approximately 1800 C for 15 to 30 minutes (this is for Pellethane; other plastics require different parameters.); (6) Sixth, the assembly is removed from the oven and cooled. The silicone sheath is removed once the assembly has cooled; and (7) Seventh, the wound coil is removed from the mandrel. 15 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, 20 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 25 been made from 0.026" 1.D. to 0.75" 1.D. and with wires from 0.004" diameter to 0.008" inch diameter. 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 30 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. 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 -12 accomplished with split mandrels and sacrificial mandrels that could be removed by dissolving in acid by way of example. Examples disclosed herein may be applied in the construction of the following products, at least in part if not in whole: 5 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 10 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. More specifically, the sheath would be capable of being coated internally as well 15 as externally with friction reducing coatings such as hydrophilic coatings as well as heperanized coatings or other medically beneficial surface treatment. 2. Urological sheaths: Different urological sheaths can be produced by the methods disclosed herein, e.g., ureteral access sheaths, urethral and bladder access sheaths, and kidney access sheaths modified to direct a scope for various 20 procedures. 3. Ureteral stents: These can be made 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 25 uncomfortable for the patient. The stent would be both small and flexible and yet easy to place due to its inherent column strength. 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 a bonding or fusing process with a braided structure instead of a coil. 30 In another possibility, a folded structure could be made that would allow the cannula sheath to be inserted first followed by the cannula itself. 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. The following benefits can be achieved - the tubing would be kink H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 13 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 would reduce the overall weight of plastic to 5 approximately 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. 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 10 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. 7. Vacuum tube: Processes taught herein would be beneficial to any situation, either medical or non-medical, where the need exists for a vacuum tube to be thin 15 walled and preferably kink resistant. This process could also be used to produce thin walled pressure tubes. 8. Split sheath introducers: In a modified method, a split sheath introducer can be made. 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 20 sheath together. 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. 25 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. 11. G-tubes/J-tubes: Gastronomy and jujenostomy tubes are used for enteral 30 feeding and would likewise benefit from reduced diameters, enhanced column strength for insertion, and kink resistance for safety. 12. ERCP catheters: Extracoporeal retrograde cholangeopancreatography catheters are very long catheters typically used to treat gallstones in the cystic H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 14 duct. These would benefit from the increased column strength and reduced wall thickness as well as high kink resistance. 13. Endoscope shafts: Flexible and steerable endoscopes require shafts that can give good protection to the internal components as well as provide regions of 5 variable flexibility and good column stiffness throughout. The shafts must also accommodate multiple lumens. 14. Drainage tubes: Drainage and suction tubes would also benefit from thin walls, lightweight and kink resistance. 15. Guide catheters: Guide catheters commonly used in cardiology to gain access 10 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 15 putting relatively stiff elements along the length of the shaft or by altering the plastic used to extrude over the wire. 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 20 performed or merely patient discomfort and possibly increase the chances of an infection. By producing portions of them by methods disclosed herein, it is possible to create very crush as well as kink resistant shunts. 17. Guidewires: Guidewires are used in a number of applications including urology and radiology. They are commonly constructed with close wound stainless steel 25 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 by methods disclosed herein. 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 30 foot or longer length. Here again the advantages of reinforced thin walls with excellent column strength would be very helpful. 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 H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 15 resistance and crush resistance as well as excellent flexibility. Various coatings and surface modifications can be applied. 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 5 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. 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 10 for the embolectomy catheters, they may benefit from the educed profile, increased inflation lumen and guidewire lumens. 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 15 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 processes disclosed herein 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. Processes 20 disclosed herein would not interfere with any of the commonly used coatings and they may show up better on ultrasound. 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 25 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. Throughout this specification and the claims which follow, unless the context 30 requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

H:\azm\Intrwovn\NRPortbl\DCC\AZM\5315425_I.doc-16/07/2013 - 16 The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge 5 in the field of endeavour to which this specification relates.

Claims (19)

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 5 elements arranged in series and fused or bonded together forming a continuous tubular structure along a longitudinal axis, wherein the composition of the ring-shaped elements varies in different portions or sections of the tubular structure, wherein at least one of the ring shaped elements is truncated along the longitudinal axis to provide a bending bias, and wherein the ring-shaped elements are assembled in accordance with a preferred flexural 10 modulus within portions or sections of the 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. 15

4. The medical tubing of claim 1, wherein the ring-shaped elements comprise 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 any one of the preceding claims, wherein the ring-shaped 20 elements have different flexural moduli.

6. The medical tubing of any one of the preceding claims, wherein the ring-shaped elements comprise a combination of flexible and rigid ring-shaped elements assembled along different portions or sections of the tubular structure.

7. The medical tubing of claim 4, wherein the metallic rings are coated with plastic and 25 are assembled with alternating elastomeric rings.

8. The medical tubing of claim 6, 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. H Sgmgm 4R nICCG~0976 doc. 1 M,4215 - 18

9. The medical tubing of claim 1, wherein the ring-shaped elements are metallic and are bonded with a resilient, flexible elastomeric adhesive.

10. The medical tubing of any one of the preceding claims, wherein the ring-shaped elements have different lengths and are fused closer or further apart to one another 5 depending on the characteristics of a portion or section of the tubing.

11. The medical tubing of any one of the preceding claims, further comprising a secondary lumen and a pull wire to control the tubular structure.

12. The medical tubing of any one of claims 1 to 11, wherein the ring-shaped elements comprise ones which are truncated, the truncated elements comprising of alternating flexible 10 ring-shaped elements and rigid ring-shaped elements.

13. The medical tubing of any one of the preceding claims, wherein the ring-shaped elements vary in diameter in different portions or sections of the tubular structure.

14. A method of manufacturing a medical tubing having a length with variable characteristics, the medical tubing comprising a plurality of individual, discrete, generally ring 15 shaped elements arranged in series and fused together to form a continuous tubular structure along a longitudinal axis, wherein the composition of the ring-shaped elements vary in different portions of sections of the tubular structure; wherein at least one of the ring-shaped elements is truncated along the longitudinal axis to provide a bending bias; and wherein the ring-shaped elements are assembled in accordance with a preferred flexural modulus within 20 portions or sections of the tubular structure, the method comprising the steps of: placing the plurality of ring-shaped elements upon a support member or a mandrel in a series arrangement; and forming the plurality of ring-shaped elements into a continuous tubular structure.

15, The method of claim 14, further including the step of heating the plurality of 25 ring-shaped elements to fuse them together over the support member or mandrel.

16. The method of claim 15, 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. H 5 ~Igncnemo en'.RPcntDCC GWA7IC6762 I.docx25/0)52I5 - 19

17. The method of claim 14, further including the step of fusing the plurality of ring-shaped elements together over the support member or mandrel with a solvent or other chemical compound.

18. The method of claim 14, further including the step of bonding together the plurality of 5 ring-shaped elements upon a support member or mandrel with an adhesive.

19. The method of claim 14, further comprising coating the tubular structure with an elastomeric adhesive or dispersion.