WO2004034874A2

WO2004034874A2 - Parylene-coated silicone t-tubes and method of use thereof

Info

Publication number: WO2004034874A2
Application number: PCT/US2003/032526
Authority: WO
Inventors: Norbert Thompson
Original assignee: Norbert Thompson
Priority date: 2002-10-15
Filing date: 2003-10-15
Publication date: 2004-04-29
Also published as: AU2003301246A8; AU2003301246A1; WO2004034874A3

Abstract

Parylene-coated silicone T-tubes that exhibit a certain biocompatible relationship such that the occurrence of obstruction due to mucous secretion and the occurrence of granulation tissue formation is minimal, if not avoided, and further demonstrate desired chemical resistance to acidic and/or corrosive bodily elements, thus enabling an improved method for rehabilitation of tracheal stenosis, for temporary aid in laryngotracheal injuries, for support of a reconstituted trachea, and for providing an airway for irreparable cervical trachea.

Description

PARYLENE-COATED SILICONE T-TUBES AND METHOD OF USE THEREOF

CROSS-REFERENCE TO RELATED APPLICATION

To the full extent permitted by law, the present application claims priority to and the benefit as a patent treaty cooperation application to provisional patent application entitled "Parylene-coated silicone T-tubes" filed on October 15, 2002, having assigned Serial No. 60/418,391.

TECHNICAL FIELD

The present invention relates generally to coated medical devices, and more specifically to a parylene-coated silicone T- tube and method of use thereof. The present invention is particularly suitable for, although not strictly limited to, use as a stent to aid in the rehabilitation of tracheal stenosis, use as a stent to temporarily aid in laryngotracheal injuries, use to support a reconstituted trachea, use as a stent to provide an airway for cervical trachea that cannot be repaired, and/or any appropriate short or long term medical application of rolled silicone sheeting stent, silicone tracheal T-tubes, and/or other permanent contact T-tubes.

BACKGROUND OF THE INVENTION

Pluralities of factors are considered in the successful development of any implantable medical device, including, but not limited to, specificity of material, device application and/or the desired durational contact of the device once implanted. As such, inherent in the contemplation and proper development of such medical devices is the necessity of these devices to possess a certain requisite degree of biocompatibility and chemical resistance, much of which is largely dependent upon the specific application of the device itself.

Specifically, long-term or permanent contact medical devices must demonstrate a bio-cooperative or biocompatible relationship such that the occurrence of immune rejection is minimal, if not avoided, and must further resist the acidic and/or corrosive bodily elements, such as enzymes, proteins and/or lipids. In addition, in order to develop bio-stable medical devices and to reduce and/or eliminate disadvantageous side effects from the utilization or implantation thereof, such as epithelialization and/or the occurrence of granulation tissue formation, most metallic medical devices must be treated or medically coated with a protective or isolative chemical or polymeric substrate. For example, silicone coating is commonly utilized to coat metal stents.

Silicone, or polydimethylsiloxane, is generally biocompatible and is commonly used to form elastomeric stents and tubes. The flexible nature of silicone provides important insertion and manipulation benefits for certain medical applications. For example, T-tubes formed from silicone are commonly utilized used as stents in the rehabilitation of tracheal stenosis, in laryngotracheal injuries, for supporting reconstituted trachea, and to provide an airway for irreparable cervical trachea. Disadvantages of such silicone T-tubes, both in addition to and in common with the disadvantages of metal stents, however, are widely recognized, wherein a common theme pervades throughout the literature, that the ideal stent has yet to be designed.

One such disadvantage is that silicone T-tubes, and metal stents, can inhibit mucosiliary function and can encourage obstruction through secretion accumulation, especially when a small inner diameter is utilized. This often necessitates repeated bronchoscopies for analysis of mucous secretion status. Moreover, although medical devices formed from silicone substrates have generally exhibited requisite biocompatibility, there remains a disadvantageously high coefficient of friction, wherein such silicone devices have a tendency of frictionally contacting the inner walls of the implantation site and, thus, contributing to granulation tissue formation thereabout.

In recognition of the potential obstruction problems and dangerous microbiologic flora associated with granulation tissue, fiber optic laser treatments have been specifically designed for treatment thereof. Additionally, attempts 'at formulation of a T-tube, especially for use as an airway stent, that will reduce or eliminate the disadvantages of silicone and/or metal abound. A large variety of materials and constructions continue to be examined, including biodegradable or bioabsorbable formulations.

Parylene, or polyparazylylene, is a polymer with characteristics rendering it suitable for coating applications in biomedical and electronic arts. As a biocompatible polymer, parylene coating of certain medical devices is known. However, despite the plethora of attempts in designing or elucidating an improved, or perfected device for tracheal stenting applications, no attempts have been made to apply a parylene coating to silicone T-tubes for use in such treatments.

Therefore, it is readily apparent that there is a need for parylene-coated silicone T-tubes for use as a stent to aid in the rehabilitation of tracheal stenosis, for use as a stent to temporarily aid in laryngotracheal injuries, for use to support a reconstituted trachea, and for use as a stent to provide an airway for cervical trachea that cannot be repaired, wherein the requisite degree of biocompatibility and chemical resistivity is inherent, wherein mucosiliary function is not inhibited within minimal T-tube inner diameters, and wherein long-term contact of T-tubes is supported without the occurrence of granulation tissue formation, thus avoiding the above-discussed disadvantages. BRIEF SUMMARY OF THE INVENTION

Briefly described, in a preferred embodiment, the present invention overcomes the above-mentioned disadvantages, and meets the recognized need for such a device by providing parylene- coated silicone T-tubes that exhibit a certain biocompatible relationship such that the occurrence of obstruction due to mucous secretion and the occurrence of granulation tissue formation is minimal, if not avoided, and further demonstrates desired chemical resistance to acidic and/or corrosive bodily elements, thus enabling medical application of the improved T- tubes for use as a perfected stent in tracheal treatments.

According to its major aspects and broadly stated, the present invention in its preferred form is an improved method for rehabilitation of tracheal stenosis, for temporary aid in laryngotracheal injuries, for support of a reconstituted trachea, and for providing an airway for irreparable cervical trachea, wherein a parylene-coated silicone T-tube is utilized as a stent, thereby retaining the benefits inherent in known treatment methods relying on silicone T-tubes, but enabling superior lubricity via a targeted parylene-coating, and thereby minimizing mucosal occlusion and epithelial damage inherent in presently available silicone T-tube methods.

More specifically, the present invention is a silicone T- tube preferably coated with a parylene polymer, specifically, the parylene N polymer due to its superior resistance to fluids and vapor transmission. Furthermore, parylene N is preferably utilized, as it is able to effectively coat the recesses and/or crevices associated with the ridges, channels and/or folds of a variety of T-tubes. However, to better facilitate parylene coating and subsequent implantation of the coated T-tube, the interior and exterior surfaces of the T-tubes utilized in the present invention are preferably substantially rounded and/or are gently sloped. Such shaping, or formation, may also assist in the reduction of granulation tissue, especially near the distal end of the parylene coated T-tubes.

Parylene, a generic name utilized to refer to a series of polyparaxylylene polymers, is preferred and utilized as a silicone T-tube medical device coating substrate due to its desired thrombogenic effect and ability to reduce granulation tissue growth proximal the implanted medical device, particularly in treatments involving trachea.

A feature and advantage of the present invention is its ability to provide a parylene-coated silicone T-tube having a low coefficient of friction, thus facilitating implantation and long-term use/contact without excessive granulation tissue formation, if any. A feature and advantage of the present invention is its ability to reduce, if not eliminate, the occurrence of granulation tissue formation adjacent the implanted T-tube.

A feature and advantage of the present invention is its ability to reduce, if not eliminate, damaging effects on mucosiliary function traditionally realized within implanted silicone T-tubes having minimized inner diameter.

A feature and advantage of the present invention is its ability to avoid epithelialization.

A feature and advantage of the present invention is its ability to offer an improved method for rehabilitation of tracheal stenosis, for treatment in laryngotracheal injuries, for supporting reconstituted trachea, and to provide an airway for irreparable cervical trachea.

Another feature and advantage of the present invention is that its use as a tracheal stent is ideal.

Another feature and advantage of the present invention is that such a method of use diminishes the need for, or avoids, repeated bronchoscopies for analysis of secretion accumulation conditions. A feature and advantage of the present invention is that such a method decreases the potentially dangerous incidence of microbiologic flora associated with granulation tissue by decreasing the incidence of granulation tissue following treatment.

A feature and advantage of the present invention is the ability of such a method of treatment reduces or eliminates the need for subsequent fiber optic laser treatments for granulation tissue removal.

A feature and advantage of the present invention is its biocompatibility.

A feature and advantage of the present invention is its chemical resistance.

A feature and advantage of the present invention is the ability of such a method of use to avoid initiating a foreign- body reaction by minimizing tissue irritation by the tubes.

A feature and advantage of the present invention is the ability of the parylene-coated silicone T-tube to eliminate electrostatic attraction between the coated T-tube and airborne dust and/or particulate, thus maintaining sterility once removed from a hermetically sealed package prior to implantation. A feature and advantage of the present invention is its ease of manufacture.

A feature and advantage of the present invention is its ability to facilitate suctioning/removal of bodily fluid from within the implanted T-tube, thus reducing accretion of bodily fluid, therein.

These and other objects, features and advantages of the present invention will become more apparent to one skilled in the art from the following description and claims when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by reading the Detailed Description of the Preferred and Alternate

Embodiments with reference to the accompanying drawing figures, in which like reference numerals denote similar structures and refer to like elements throughout, and in which:

FIG. 1 is a cross-sectional view of a parylene-coated silicone T-tube according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED

AND ALTERNATIVE EMBODIMENTS

To the full extent permitted by law, the present application claims priority to and the benefit as a patent treaty cooperation application to provisional patent application entitled "Parylene-coated silicone T-tubes" filed on October 15,

2003, having assigned Serial No. 60/418,391.

In describing the preferred and alternate embodiments of the present invention as illustrated in FIG. 1, specific terminology is employed for the sake of clarity. The invention, however, is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish similar functions.

Referring now to FIG. 1, the present invention in its preferred embodiment is a parylene coated silicone T-tube 10, preferably possessing T-tube 20, wherein T-tube 20 is preferably formed from silicone, and wherein T-tube 20 is preferably any conventionally available and/or industry-standard T-tube preferably possessing substantially rounded and/or gently sloped interior and exterior surfaces to avoid sharp angles at tubular bends, thereby facilitating coating and subsequent implantation.

Although T-tube 20 is the preferred substrate for parylene coating, it is anticipated within the scope of the present invention that rolled silicone sheeting could alternately be utilized, wherein the alternate configuration could be appropriately indicated and desired.

T-tube 20 is preferably coated with polymer 30, wherein polymer 30 is preferably a parylene N polymer. Specifically, T- tube 20 is coated with polymer 30 to preferably form a ^ to 2 micron-thick layer 35 of polymer 30 on both inner surface 22 and outer surface 24 of T-tube 20.

Polymer 35 is preferably applied to inner surface 22 to facilitate suctioning/removal of bodily fluid from within implanted T-tube 20, and to reduce impact on mucosiliary function, thus reducing accretion of bodily fluid therein. Additionally, polymer 35 is preferably applied to outer surface 24 to reduce the inherent electrostatic nature of silicone, to facilitate implantation of T-tube 20, and to promote long-term contact of T-tube 20 with the implantation site via the reduction and/or elimination of granulation tissue formation.

The thickness of layer 35 is preferably confined to the range of ^ to 2 microns thick, as too thick of a layer 35 may make implantation of T-tube 20 difficult, and may result in layer 35 peeling off and/or being easily removed from inner and outer surfaces 22 and 24, respectively, of T-tube 20. Too thin a layer 35 may result in insufficiency of coating of the substrate material, and subsequent reduction in utility of the coating. Although layer 35 is preferably >. to 2 microns thick, it is contemplated in an alternate embodiment that layer 35 could possess any thickness as required by industry standard and/or considerations of efficacy.

It is contemplated in yet another alternate embodiment that Parylene C and/or Parylene D could also be utilized to coat T- tube 20 should such an application be desired.

The parylene coating process of T-tube 20 is preferably implemented via known coating processes utilized by Specialty Coating Systems of Speedline Technologies, wherein the process is embodiment within an article entitled "Parylene: A Biostable, Bicompatible Coating For Medical Devices" (Copyright 2000), and incorporated herein by discussion.

Parylene N polymer 30 is preferably deposited onto T-tube 20 from the vapor phase, wherein the deposition occurs preferably at a pressure of 0.1 torr and in a deposition chamber where the mean free path of the Parylene N polymer 30 gas molecule is around 0.1 cm, thus permitting uniform coating of the entire surface of T-tube 20.

The coating process of T-tube 20 with parylene N polymer 30 preferably involves (1) vaporization of the solid dimer at approximately 150° C; (2) pyrolysis of the dimer at the two methylene-methylene bonds at about 680° C, thus yielding the monomeric diradical, para-xylylene; and, (3) introduction of the monomer into the deposition chamber, wherein the deposition chamber is preferably at room temperature so as to permit the monomer to simultaneously adsorbs and polymerize onto T-tube 20 for conformal coating thereof.

In use, device 10 is preferably suitable for implantation as a stent to assist in the rehabilitation of tracheal stenosis; as a stent to temporarily aid in laryngotracheal injuries; as a stent to provide an airway for a non-repairable cervical trachea; and/or to support a reconstituted trachea. Although tracheal and/or thoracic applications of device 10 are the preferred medical applications, it is contemplated in an alternate embodiment that device 10 could be utilized and/or modified/adapted to be utilized in any desired medical application, such as, for exemplary purposes only, gastrointestinal applications.

Having thus described exemplary embodiments of the present invention, it should be noted by those skilled in the art that the within disclosures are exemplary only, and that various other alternatives, adaptations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the specific embodiments illustrated herein, but is limited only by the following claims.

Claims

WHAT IS CLAIMED IS :

1. A stent for use in medical implantations, said stent comprising a silicone substrate and a parylene polymer, said polymer substantially coating said substrate.

2. The stent of claim 1, wherein said polymer comprises parylene N.

3. The stent of claim 1, wherein said polymer comprises parylene C.

4. The stent of claim 1, wherein said polymer comprises parylene D.

5. The stent of claim 1, said stent further comprising substantially rounded interior and exterior surfaces.

6. The stent of claim 1, said stent further comprising gently sloped interior and exterior surfaces.

7. The stent of claim 1, said stent comprising a t-tube.

8. The stent of claim 1, said stent comprising a y-tube.

9. The stent of claim 1, said stent comprising rolled silicone sheeting.

10. A method of aiding in the rehabilitation of tracheal stenosis, temporarily aiding in laryngotracheal injuries, supporting a reconstituted trachea, and providing an airway for irreparable cervical trachea, comprising the steps of: a) obtaining an elastomeric substrate indicated for use in the rehabilitation of tracheal stenosis, for temporarily aiding in laryngotracheal injuries, for supporting a reconstituted trachea, and for providing an airway for irreparable cervical trachea; b) applying a coating of a parylene polymer to said elastomeric substrate; c) proceeding with rehabilitation of tracheal stenosis, application of aid to a laryngotracheal injury, support of a reconstituted trachea, or provision of an airway for irreparable cervical trachea via utilization of said indicated elastomeric substrate having said parylene polymer coating thereon.

11. A method of decreasing incidence of mucosal obstruction and granulation tissue in treatments involving tracheal implantation of silicone T-tubes, comprising the steps of: a) obtaining a silicone T-tube having an interior surface and an exterior surface; b) coating said interior surface and said exterior surface of said silicone T-tube with polyparazylylene; c) implanting said polyparazylylene coated silicone T- tube.

12. The stent of claim 1, wherein said parylene polymer coating is configured to minimize tissue irritation realized from said stent .

13. The stent of claim 1, wherein said parylene polymer coating is thick enough to substantially shield the electrostatic attraction of said silicone substrate of said stent.

14. The stent of claim 8, wherein said y-tube has an inner diameter, wherein said parylene polymer coating said inner diameter of said y-tube is defines a new inner diameter, said new inner diameter defined to facilitate mucusiliary function.

15. The stent of Claim 1, wherein said parylene polymer coating has a thickness within the approximate range of ^ to 2 microns.

16. The method of claim 10, further comprising a method of gastrointestinal treatment; wherein step a) further comprises obtaining an elastomeric substrate indicated for use in gastrointestinal treatment; and wherein step c) further comprises proceeding with gastrointestinal treatment. Parylene-coated silicone T-tubes that exhibit a certain biocompatible relationship such that the occurrence of obstruction due to mucous secretion and the occurrence of granulation tissue formation is minimal, if not avoided, and further demonstrate desired chemical resistance to acidic and/or corrosive bodily elements, thus enabling an improved method for rehabilitation of tracheal stenosis, for temporary aid in laryngotracheal injuries, for support of a reconstituted trachea, and for providing an airway for irreparable cervical trachea.