GB2507474A

GB2507474A - Medical device with hydrophilic coating

Info

Publication number: GB2507474A
Application number: GB1216632.8A
Authority: GB
Inventors: Simon Talbot
Original assignee: P3 MEDICAL Ltd
Current assignee: P3 MEDICAL Ltd
Priority date: 2012-09-18
Filing date: 2012-09-18
Publication date: 2014-05-07
Also published as: GB201216632D0

Abstract

A medical device 1 for insertion into a passageway of a human body comprises an elongate body 10 having a hydrophilic outer surface 4. The device is one of a bougie or a stylet and may be contained in a sealed container together with a lubricant. The hydrophilic outer surface may have a wetting angle with water of not greater than 30 degrees. The surface may comprise polyvinylpyrrolidone. The device may be made of a plastics material, such as a thermoplastic elastomer. The container for the lubricant may be a sachet, and may be rupturable by hand to release sterile water, silicone fluid, lidocaine spray or gel.

Description

TITLE: MEDICAL DEVIECE AND SYSTEM

DESCRIPTION

TECHNICAL FIELD

The present invention relates to medical devices for insertion into a passageway of a human body, in particular bougies and stylets, in particular bougies and stylets for endotracheal applications, for example in airway emergencies and in difficult airway intubation, to opcn the airway of a person or animal to allow or guide the insertion of an endotraeheal tube or similar tubes.

BACKGROIJND ART

A bougie may he defined as a slender, flexible surgical instrument for exploring, dilating or medicating a passage of the body. Typically, a bougie is relatively thin cylinder of plastic, rubber, metal or another material that a physician inserts into or through a body passageway, such as the esophagus, to diagnose or treat a condition. A bougie may be used to widen a passageway, guide another instrument into a passageway, such as endotracheal tube into the airway, or dislodge an object. Bougies can be used when intubation is (or is predicted to be) difficult -often helpful when the tracheal opening is anterior to the visual field. During laryngoscopy, the bougie is carefully advanced into the larynx and through the cords until the tip enters a mainstem bronchi. While maintaining the laryngoseope and bougie in position, an assistant threads an endotracheal tube over the end of the bougie, into the larynx. Once the endotracheal tube is in place, the bougie is removed.

A stylet may be defined as a slender probe that can be inserted into a catheter, cannula or similar tubc to maintain rigidity. Typically, a stylet is a mafleable metal alloy rod usually completely sealed by a thin sheath of plastic material designed to be inserted into the endotiracheal tube, catheter or any similar surgical tube to make the tube stiffer and conform better to the uppcr airway anatomy or any other passage of the patient to facilitate trachea! intubation. Oncc the cndotracheal tube, catheter or any similar surgical tubc is in placc, the stylet is retracted. In an emergency, difficulty in withdrawing the stylet from tracheal tube, catheter or any similar surgical tube may be detrimental to the patient. In particular, tracheal tube displacement or inability to remove the stylet at this critica! time can result in morbidity or mortality secondary to inadequate oxygenation.

Bougies and stylets share the common characteristic of slenderness, specifically a ratio of length to maximum transverse dimension of at least thirty, in order that they might extend sufficiently along a narrow body passage. They also share the common characteristic of limited flexihi!ity in bending.

DISCLOSURE OF INVENTION

According to the present invention, there is provided a medical device for insertion into a passageway of a human body, wherein the device comprises an elongate body having a hydrophilic outer surface and wherein the device is one of a bougie or a stylet.

A hydrophilie outer surface exhibits water-attracting characteristics and contributes in dynamic hydrogen bonding with surrounding water, resulting in extremely low coefficients of friction. These characteristics will result in material surfaces that are wettable, lubricious, and appropriate for specific biological interactions (lubricity is the measure of the reduction in friction, which is a property that describes how slippery a surface is). It follows that a bougie or stylet having a hydrophilic outer surface will, once it touches water, become very lubricating. l]iis in turn makes intubation easier, much less traumatic on surface tissue and minimises the risk of stabbing of the paticnt internal organs.

In the case of a stylet, this also enables easy removal from an -e.g. endotracheal -tube without displacing that tube from its position. The hydrophilic outer surface may have a wetting angle with water of not greater than 30 degrees.

The hydrophilie outer surface may comprise polyvinylpyrrolidone. The bougie or 1 0 stylet may comprise a substrate comprising plastics material. The bougie or stylet may comprise a substrate selected from the group of high density polyethylene, low density polyethylene, polyurethane, polyiinide, nylon or silicone. The substrate may he a thermoplastic elastomer.

The bougie or stylet may comprise a first elongate portion extending along a first longitudinal axis and, at one end of the first portion, a second elongate portion extending along a second longitudinal axis inclined to the first longitudinal axis. In particular, the second longitudinal axis may be inclined to the first longitudinal axis at an angle in the range 30 to 50 degrees, in particular approximately forty degrees.

The first portion may have a high aspect ratio. In particular, the first portion may have a length L along the first longitudinal axis that is at least thirty times greater than its greatest dimension transverse to that axis.

The second portion may have a length along the second longitudinal axis that is at least twenty times less than the length of the first portion along the first longitudinal axis, in particular about thirty times less, specifically about twenty six times less.

The outer surface of the second portion may be hydrophilic and the outer surface of the first portion non-hydrophilic. The outer surfaces of both the second and the first portion may be hydrophilic.

The first or second portion of the bougie or stylet may have a surface that is modified so as to render it hydrophilic. In particular, the first or second portion may comprise a monolithic body that forms the hydrophilic outer surface of the bougie.

The first or second portion of the bougic or styict may comprisc a body comprising a first material and having thereon a coating comprising a second, different material, the coating having hydrophilic properties. The coating may be bonded to the body.

According to the present invention, there is also provided a system comprising a sealed container containing a medical device as set out above together with a lubricant. The sealed container may be a pouch. The lubricant may be contained in a further sealed container within the sealed container, the further container being configured to be opened, thereby allowing the lubricant to come into contact with the hydrophilic outer surface of the medical device. The further container may be configured to rupture in a control led manner under an applied force. The further container may be a sachet. The system may be configured to allow the further container to be opened, in particular burst, by action from outside the sealed container, in particular the application of pressure by hand. The lubricant may comprise sterile water, silicone fluid, lidoeaine spaiy or lidoeaine gel.

BRIEF DESCRIPTION OF DRAWINGS

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a bougie according to a first embodiment of the invention; Figure 2 illustrates the hydrophilicity of a bougie or stylet according to the invention; Figure 3 is a view of a stylet according to a second embodiment of the invention; Figure 4 is an illustration oIthe stylet of figure 3 in use with a tracheal tube.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Figure 1 shows a bougie I according to the invention. Typical dimensions for such bougies include 5th x 470mm, loch x 600mm, lSch x 600mm, lOch x 800mm and l5eh x 800mm.

The bougie 1 has a body comprising a first elongate portion 2 extending along a first longitudinal axis AA and, at one end 5 of the first portion, a second elongate portion 3 extending along a second longitudinal axis BB, inclined to the first axis AA. As shown, axis BB is inclined to axis AA at an angle N of approximately 40 degrees. In use, it is the second portion 3 -typically called the distal end' of the bougie -that is inserted when intubating a patient, the first portion -typically called the proximal end' -serving as a handle.

The first portion 2 is cylindrical in form and has a high aspect ratio, having a length L along axis AA that is approximately thirty times greater than its maximum transverse dimension t. The second portion 3, which is similarly cylindrical with a similar maximum transverse dimension t, has a length E at least twenty -in the example shown twenty six -times less than the length L. In the embodiment shown, the first and second portions 2,3 of the bougie are defined by a body 10 of plastic, rubber or metal having a hydrophilic coating 4 formed thereon. The (first, non-hydrophilic) material of the body and the (second, hydrophilic) material of the coating are different. In anothcr embodiment (not shown), the hydrophilic coating 4 is formed only on that part of the body in the second portion of the bougie.

As is known, the hydrophilicity of the surface of the bougie or stylet may be defined by the relative degree of interaction of a lubricant in its liquid state with that surface, specifically by the value of the contact angle of water or any other lubricant in its liquid state droplet on the solid surface of the bougie or stylet. Referring to figure 2, the solid S surface 11 of the bougic or stylet is treated or coated with an appropriate hydrophilic coating so that the contact angle 16 of water 12 or any other the lubricant is lcss than 30 degrees.. Vapour is indicated at 13, with the solid-vapour interfacial tension being indicated at 14 and the liquid-vapour interfacial tension at 15.

In another embodiment (not shown), the body 10 of plastic, rubber or metal has a surface that is modified so as to render it hydrophilic. There is no separate hydrophilic coating -rather, the body is monolithic and forms the hydrophilic outer surface of the bougie. Again, only that part of the body in the second portion of the bougie may be modified to render it hydrophilie.

Hydrophilic coatings and surface treatment methods are known per se. In the present embodiment, the coating is made up of a chemically cross-linked supporting polymer type network with long-chain hydrophilic molecules well entangled within it.

Polyvinylpyrrolidone (PVP) is a commonly used hydrophilic molecule, which binds exceptionally well to polar molecules owing to its polarity. The supporting polymer network is cross-linked in a covalent bonding fashion, which contributes to better interconnected properties. The hydrophilic molecule is blended with aqueous polymer dispersion. A hydrophilised cross-linking agent such Basonat® from BASF that cross-links the supporting polymer matrix is added to improve coating reliability. Room temperature curing cross-linking agent is used.

Coating methods include dip coating, where the respective portion(s) of the body are lowered into a suitable coating solution including aqueous-based lubricious coatings and then withdrawn at an appropriate speed, spray coating and film coating processes. Such processes may result in the entirety of the surface of a portion being coated/treated.

The bonding between the bougie device surface and the coating can be covalent or non-covalent, or also through polar, hydrogen, Van der Waals bonding and mechanical interactions. The curing of the coating may be performed by exposing the coated bougie device to a predetermined level of ultraviolet light for a predetermined time. A suitable bonding is selected so that the interactions between the hydrophilic coating and the bougie device surface will withstand any environmental, chemical and mechanical stresses that the device may be expected to experience during its shelf life and use.

The surface treatment or coating may he selected in accordance with the intended sterilisation process of the bougie device and its intended application.

The substrates of the bougie or stylet coated with hydrophilic lubricious coating can made of polyethylene (l-IDPE and LDPF), polyurethane, polyimide, nylon, thermoplastic elastorner, silicone or any other plastic type material. Typical material properties fall within the following ranges: elongation at break 60-85%, tensile modulus 2.4-4.3 GPa, tensile strength 45-72 MPa.

The surface treatment and coating are also selected to last for duration of the shelf life of the bougie device, taking into account any modifications to the packaging of the device to protect the coating from exposure to aging factor such as UV light exposure, humidity or temperature.

Figure 3 is a view of an intubating stylet 20 according to a second embodiment of the invention and comprising a metal alloy rod 21 having a proximal end 22 and a distal end 24 enclosed in a cylindrical sheath 25 made of impermeable plastic or plastic type material and provided with a hydrophilic coating as described above with respect to the hougie. The sheath is tightly enveloping the rod, but the two are not attached to one another so that they may move relative to each other and they may bend and flex longitudinally independently of each other. The intubating stylet 20 has a ioop 23 in its proximal end and is made of such metal or metal alloy that it is capable of being bent into a desired configuration and will remain in such shape.

Figure 4 shows the stylet 20 of figure 3 in use with a tracheal tube 35 having a distal end 31, a tracheal cuff 36 and a so-called Murphy eye' 37. At its other, proximal end 39, the tracheal tube has a connector 38. It will be seen that the loop 23 of the stylet 20 has to 1 0 he larger in size than the inside diameter of the tracheal (or any other endo-) tube to prevent the stylet from advancing more than inLended. Moreover, the length of the stylet 20 from the end of the loop 23 at the proximal end to distal end must be at least two and half centimetres shorter than the length of the tracheal tube (or any other catheter or other anaesthetic -surgical tube). This feature is for safety reasons and is less traumatic by leaving the distal end 31 of the tube flexible.

In one embodiment, the intubating bougie or intubating stylet may be packaged in a pouch together with a small sachet of lubricants, which could contain sterilc water, silicone fluid, lidocaine spary or lidocaine gel. When the intubating bougie or intubating stylet is to be used, the small sachet of lubricant is pressed by hand from outside of the pouch until it bursts, allowing the lubricant to be dispersed all over inside the pouch and hence wetting the surface of the hougie/stylet, thereby making the hydrophilic surface active. The pouch can then he opened, freeing the bougie or stylet for use. As previously discussed, the invention will decrease the friction between the vocal folds through the glottis opening as well as the trachea wall and the bougie, ibeilitating insertion of the bougie into the patient airway and allowing easy removal of the stylet without dislodging the tracheal tube.

II should be understood that this invention has been described by way of examples only and that a wide variety of modifications can be made without departing from the scope of the invention.

Claims

CLAIMS1. A mcdical device for insertion into a passageway of a human body, wherein the device comprises an elongate body having a hydrophilic outer surface and wherein the device is one of a bougie or a stylet.
2. Medical device according to claim 1, wherein the hydrophilic outer surface has a wetting angle with water of not greater than 30 degrees.
3. Medical device according to claim I or claim 2, wherein the hydrophilic outer surface comprises polyvinylpyrrolidone.
4. Medical device according to any preceding claim, wherein the bougie or stylet comprises a substrate comprising plastics material.Y)
5. Medical device according to claim 4, wherein the bougie or stylel. comprises a r substrate selected from the group of high density polyethylene, low density polyethylene, O polyurethane, polyimide, nylon or silicone.0
6. Medical device according to claim 4 or claim 5, wherein the substrate is a thermoplastic elastomer.
7. Medical device according to any preceding claim, wherein the bougie or stylet comprises a first elongate portion extending along a first longitudinal axis and, at one end of the first portion, a second elongate portion extending along a second longitudinal axis inclined to the first longitudinal axis.
8. Medical device according to claim 7, wherein the second longitudinal axis is inclined to the first longitudinal axis at an angle in the range 30 to 50 degrees.
9. Medical device according to claim 8, wherein the second longitudinal axis is inclined to the first longitudinal axis at an angle of approximately forty degrees.
10. Medical device according to any one of claims 7 to 9, wherein the first portion has a high aspect ratio.
11. Medical device according to claim 10, wherein the first portion has a length L along the first longitudinal axis that is at least thirty times greater than its greatest dimension transverse to that axis.
12. Medical device according to any one of claims 7 to 11, wherein the second portion has a length along the second longitudinal axis that is at least twenty times less than the length of the first portion along the first longitudinal axis.
13. Medical device according to claim 12, wherein the second portion has a length along the second longitudinal axis that is about thirty times less than the length of the first portion along the first longitudinal axis.0')
14. Medical device according to claim 13, wherein the second portion has a length along r the second longitudinal axis that is twenty six times less than the length of the first portion a, O along the first longitudinal axis.0
15. Medical device according to any one of claims 7 to 14, wherein the outer surface of the second portion is hydrophilie and the outer surface of the first portion is non-hydrophilic.
16. Medical device according to any one of claims 7 to 14, wherein the outer surfaces of both the second and the first portion are hydrophilie.
17. Medical device according to claim 15 or claim 16, wherein the first or second portion of the bougie or stylet has a surface that is modified so as to render it hydrophilic.
18. Medical device according to claim 15 or claim 16, wherein the first or second portion comprises a monolithic body that forms the hydrophilie outer surface of the bougie.
19. Medical device according to claim 15 or claim 16, wherein the first or second portion of the bougie or stylet comprises a body comprising a first material and having thereon a coating comprising a second, different material, the coating having hydrophilic propcrties.
20. Medical device according to claim 19, wherein Uc coating is bonded to the body.
21. A system comprising a sealed container containing a medical device according to any preceding claim together with a lubricant
22. System according to claim 21, wherein the sealed container is a pouch.
23. System according to claim 21 or claim 22, wherein the lubricant is contained in a ftirther sealed container within the sealed container, the further container being configured to be opened, thereby allowing the lubricant to come into contact with the hydrophilic outer surface of the medical device.Y)
24. System according to claim 23, wherein the further container is configured to rupture r in a controlled manner under an applied force. a,0
25. System according to claim 24, wherein the furthcr container is a sachet.0
26. System according to claim 24 to claim 25, wherein the system is conligured to allow the further container to bc opened, in particular burst, by action from outside the sealed container, in particular the application of pressure by hand.
27. System according to any one of claims 21 to 26, wherein the lubricant is selected from the group of sterile water, silicone fluid, lidocaine spary or lidocaine gel.