Patent Description:
Tracheal tubes are used to enable ventilation, respiration or spontaneous breathing of a patient. Endotracheal tubes are inserted via the mouth or nose so that one end locates in the trachea and the other end locates outside the patient. Tracheostomy tubes are inserted into the trachea via a surgically formed opening in the neck. Tracheostomy tubes can be inserted by different techniques, such as the surgical cut-down procedure carried out in an operating theatre or a cricothyroidotomy procedure, which may be carried out in emergency situations.

Tracheostomy tubes are generally used for more long-term ventilation or where it is not possible to insert an airway through the mouth or nose. The patient is often conscious while breathing through a tracheostomy tube, which may be open to atmosphere or connected by tubing to some form of ventilator. The tube is secured in position on the patient's neck by means of a mounting flange fixed with the machine end of the shaft of the tube and positioned to extend outwardly on opposite sides of the tube. A neck tie or the like is passed around the patient's neck and its ends are secured to either end of the flange. Alternatively, sutures can be used to secure the flange in place.

Tracheostomy tubes can be made of various materials and are usually of a bendable plastics material such as PVC, polyurethane or silicone. Silicone is particularly suitable because of the softness, comfort and conformability the material provides. This is a particular advantage in tracheostomy tubes since the patient may be intubated and using a breathing machine for an extended time, usually more than one week. Silicone also has an advantage because it is not damaged by the high temperatures of an autoclave, thereby enabling a silicone tube to be cleaned and autoclaved for reuse.

It is particularly desirable for the mounting flange of a tracheostomy tube to be moulded from a soft, conformable plastics such as silicone so that it flexes readily to conform to the surface of the patient's neck. However, flanges moulded of a soft plastics material it can create problems in that the material may not be strong enough to ensure that the neck strap or sutures do not tear the flange where it is threaded through the openings used to secure the tube to the patient's neck. Mounting flanges made of some silicone materials, such as liquid silicone rubber have a poor abrasion resistance, particularly to abrasion by ties of a relatively stiff material such as those using hook and loop (Velcro) type fasteners. Over several days the abrasion can be so severe that it breaks through the edges of the openings in the flange. This can cause decannulation if not noticed by the care giver. A similar problem can exist where sutures are used with the flange. In an attempt to reduce this risk, it has been proposed to add a reinforcement member of a harder plastics around the neck tie openings, such as described in <CIT>. These reinforcement members create a problem of ensuring that the insert does not separate from the remainder of the flange because of the different compositions of the flange and inserts. In general, it is necessary to prime the contact region between the insert and the flange to reduce the risk that the insert does not peel, break free or separate from the flange. Flexing of the flange material relative to the inserts can allow micro fissures and crevices to develop in the flange material that can harbour bacteria leading to infection of the stoma. It is important to ensure that any reinforcement member does not separate from the flange since any such loose member could be inhaled or provide concern that it has been inhaled. Certain materials used to reinforce the flange openings might be damaged by elevated temperatures, thereby making the entire tube unsuitable for autoclave cleaning.

It is an object of the present invention to provide an alternative tracheostomy tube and a method of manufacturing such tubes and their flanges.

According to one aspect of the present invention there is provided a tracheostomy tube of the above-specified kind, characterised in that the flange is of a first silicone material overmoulded on two reinforcement inserts at respective ones of the openings, and that the reinforcement inserts are of a heat-cured silicone rubber material different from the first silicone material.

The silicone material of the flange and of the inserts preferably have a similar hardness. The hardness of both silicone materials is approximately <NUM> shore A. The first silicone material is preferably a liquid silicone rubber. The inserts may include a hollow tubular body with a passage extending therethrough and a projection extending outwardly of the body between opposite ends. The projection may be an annular ledge extending around the body. Opposite sides of the flange preferably lie level with opposite ends of the body of the inserts, with the passage through each body extending through the thickness of the flange, and with both sides of the projection being covered by material of the flange.

According to another aspect of the present invention there is provide a method of manufacture of a mounting flange of a tracheostomy tube including the steps of moulding two inserts of a heat-cured silicone rubber material, both inserts having a passage therethrough and an outer projection, and overmoulding the two inserts about their outer projection with a silicone material different from that of the inserts to form a mounting flange of the tube where the passage through each insert provides an opening towards opposite ends of the flange to which securing means can be secured.

The silicone material of the inserts preferably has substantially the same hardness as the silicone material overmoulded about the inserts.

According to a further aspect of the present invention there is provided a method of manufacture of a tracheostomy tube including the steps of manufacturing a mounting flange by a method according to the above other aspect of the present invention, providing a shaft of the tube with a patient end and a machine end, and attaching the mounting flange with the shaft towards the machine end of the shaft.

According to a fourth aspect of the present invention there is provided a tracheostomy tube made according to the method of the further aspect of the present invention.

A tracheostomy tube with a mounting flange and a method of manufacture of the mounting flange and tube according to the present invention will now be described, by way of example, with reference to the accompanying drawings in which:.

With reference first to <FIG>, the tracheostomy tube <NUM> has a curved shaft <NUM> of circular section moulded from a flexible plastics such as silicone. The patient, distal or forward end <NUM> of the tube <NUM> is adapted to locate in the trachea. The machine, proximal or rearward end <NUM> of the tube <NUM> extends through the tracheostomy and opens externally of the patient. The machine end <NUM> of the tube supports a laterally extending mounting flange <NUM> adapted to lie against the skin of the neck and having openings <NUM> at opposite ends that receive securing means such as the ends of a neck tie (not shown) extending around the neck. Alternatively, the securing means could take the form of sutures threaded through skin adjacent the flange <NUM>. The machine end <NUM> of the tube <NUM> also includes an externally tapered <NUM> male connector <NUM> arranged to receive a cooperating female connector (not shown) at one end of ventilation tubing. The connector <NUM> illustrated is a separate component from the shaft <NUM> and is moulded from a harder plastics than that of the shaft. Alternatively, the connector could be an integral component, one piece with the shaft. Where the patient is breathing spontaneously a connector might not be needed so the shaft could be terminated by a low-profile end fitting. The tube <NUM> is shown without any sealing cuff but it could be provided with such a conventional sealing cuff and other conventional features such as vocalisation fenestrations or suction lumens.

With reference now also to <FIG>, the rear end of the shaft <NUM> is terminated by an enlarged external circular boss <NUM> and extends through a central opening <NUM> in the mounting flange <NUM>. The flange <NUM> has a circular collar <NUM> formed around the opening <NUM> and projecting from the rear face of the flange. The collar <NUM> forms a circular cavity <NUM> within which the boss <NUM> on the shaft <NUM> is received and to which it is bonded.

The mounting flange <NUM> is moulded from a relatively soft, conformable silicone material, preferably a liquid silicone rubber with a hardness of approximately <NUM> shore A. This is preferably the same material as forms the shaft <NUM>. The flange <NUM> has two radial arms <NUM> and <NUM> projecting outwardly of the central collar <NUM> along an axis orthogonal to the plane of curvature of the shaft <NUM>. The inner part of each arm <NUM> and <NUM> has a width approximately half the diameter of the collar <NUM>. At its outer end each arm <NUM> and <NUM> flares outwardly over a tapered region <NUM> and <NUM> to an enlarged region <NUM> and <NUM> the width of which is about twice that of the inner part of the arm. The openings <NUM> for receiving the ends of the neck tie or the like are provided in these enlarged regions <NUM> and <NUM> and are reinforced by means of respective inserts <NUM> and <NUM> shown more clearly in <FIG>. The inserts <NUM> and <NUM> are retained with the flange <NUM> by overmoulding the flange material about the outside of the inserts.

The inserts <NUM> and <NUM> are also moulded from a silicone material but of a more abrasion-resistant grade of silicone than that forming the main part of the flange <NUM>, namely a heat-cured silicone rubber, such as MED-<NUM> from Avantor, Inc, having a similar hardness to the material of the flange. It has been found that by making both the inserts and the flange of silicone materials it is possible to achieve a very good bond that is free from cracks and separation even after prolonged use and flexing. The similar hardness of the two materials also has the advantage of ensuring that the inserts do not lead to localised regions of the flange that are stiffer. The inserts <NUM> and <NUM> have a generally rectangular shape with a radially extending flat plate <NUM>, which is rectangular with rounded corners and has a thickness about one quarter that of the arms of the flange. From the centre of opposite sides of the plate <NUM> projects a hollow tubular body formed by identical walls <NUM> and <NUM> of a racetrack oval shape with rounded ends <NUM>. The external lateral dimensions of the walls <NUM> and <NUM> are less than the external dimensions of the central plate <NUM> so that the plate forms an annular outer projection, ledge or ring <NUM> with an upper, rearwardly-facing surface <NUM> and a lower, forwardly-facing surface <NUM>. The upper and lower surfaces <NUM> of the walls <NUM> and <NUM> have a flat outer region <NUM> that continues as an inner rounded region <NUM>. This provides a smooth entry to a central, elongate passage <NUM> through the inserts <NUM> and <NUM> forming the openings <NUM>. The inserts <NUM> and <NUM> are embedded in the arms <NUM> and <NUM> of the mounting flange <NUM> with the passage <NUM> through each insert extending at right angles to the length of the arms. The height of the inserts <NUM> and <NUM> are equal to the thickness of the arms <NUM> and <NUM> so that the opposite surfaces of the arms lie level with the outer flat end regions <NUM> of the inserts. The ledge <NUM> of each insert <NUM> and <NUM> projects outwardly into the flange material midway across the thickness of the arms <NUM> and <NUM>. The compatible nature of the silicone materials used in the main part of the flange <NUM> and in the inserts <NUM> and <NUM> means that the flange material forms a secure bond with the outside of the inserts, around the outer surface of the upper and lower walls <NUM> and <NUM>, along the upper and lower surfaces of the ledge <NUM> and around its outer edge. The bond between the flange material and the inserts does not require any primer or other pre-treatment. The bond formed with the inserts <NUM> and <NUM> is resistant bending and flexing of the flange <NUM> without causing any separation or peeling and without creating fissures or crevices that could allow bacteria to collect. Because the inserts <NUM> and <NUM> have a similar hardness to the material of the rest of the flange <NUM> it avoids any difference in stiffness across the flange. In use, opposite the ends of the neck tie or sutures are threaded through or otherwise secured with the passages <NUM> in the inserts <NUM> and <NUM>. The abrasion-resistant nature of the material of the inserts <NUM> and <NUM> ensures that force exerted by the neck tie or sutures during use and any rubbing caused by movement does not damage the flange <NUM>, whilst the soft and conformable nature of the flange is not compromised.

Claim 1:
A tracheostomy tube including a shaft (<NUM>) and a mounting flange (<NUM>) towards the machine end (<NUM>) of the shaft, the mounting flange (<NUM>) extending radially outwardly of the tube and being provided with an opening (<NUM>) towards each end to which means can be secured to retain the tube with the patient's neck, characterised in that the flange (<NUM>) is of a first silicone material overmoulded on two reinforcement inserts (<NUM>, <NUM>) at respective ones of the openings (<NUM>), and that the reinforcement inserts (<NUM>, <NUM>) are of a heat-cured silicone rubber material different from the first silicone material.