This invention relates to tracheal tubes of the kind having a sealing member on its outside towards its patient end that is adapted, during use, to provide a seal with the tracheal wall.

Tracheal tubes are used to supply ventilation and anaesthetic gases to a patient, such as during surgery. The tracheal tube may be inserted via the mouth or nose, in the case of an endotracheal tube, or may be inserted via a surgically-made tracheostomy opening in the neck, in the case of a tracheostomy tube.

Most, but not all, tracheal tubes have some form of a sealing member on their outside which forms a seal between the outside of the tube and the inside of the trachea so that gas flow is confined to the bore of the tube and cannot flow around the outside of the tube, between the tube and the trachea. The most common form of seal is provided by an inflatable cuff that is inflated and deflated via a small bore lumen extending rearwardly along the tube and connected towards its rear end to an inflation line terminated by an inflation indicator, valve and connector. These inflatable cuffs may be of the

high-volume/low-pressure kind where the cuff is formed of a flexible material moulded with a natural annular or doughnut shape that is inflated without stretching by relatively low- pressure gas supplied via the inflation line. Alternatively, the cuff may be of the low- volume/high-pressure kind where the cuff is of an elastic material that lies close to the tube shaft when uninflated but is inflated and stretched to a larger diameter by relatively high pressure gas supplied via the inflation line. Various problems exist with both forms of cuff. One problem is that the cuff can cause damage to the tracheal lining and the formation of scar tissue, especially if the cuff is used incorrectly, such as with incorrect pressure and inadequate monitoring.

The seal on such tracheal tubes need not be formed by an inflatable cuff but could, for example, be provided by a self-inflating foam cuff or by sealing flanges or the like. In all cases, the contact of the sealing means with delicate tracheal tissue may lead to damage and trauma. It is an object of the present invention to provide an alternative tracheal tube.

According to the present invention there is provided a tracheal tube of the above- specified kind, characterised in that the sealing member has an outside surface region adapted to contact the tracheal wall where a part at least of such surface region includes an active substance selected to reduce damage to the trachea.

The active substance may be provided by a coating on the outside of the sealing member or by incorporation within the material of the sealing member. The active substance may include an anti-proliferative or immunosuppressant agent, such as including

Rapamycin. The active substance may be provided in a delivery agent of a polymer. The delivery agent may be a biodegradable or bio-resorbable polymer. The sealing member may include an expansible sealing member such as an inflatable cuff.

A tracheostomy tube according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view of the tube; and

Figure 2 is an enlarged cross-sectional view through a part of the sealing cuff of the tube shown in Figure 1.

The tracheostomy tube includes a tubular shaft 1 having a bore 2 extending along its length. The tube is formed with a relatively straight patient end portion 3 and a relatively straight machine end portion 4 linked by a curved intermediate portion 5 so that the patient and machine ends 6 and 7 are angled at about 100° to one another. The shaft 1 is extruded or moulded from a plastics material such as PVC or silicone. Towards its patient end 6 the tube has a sealing member provided by an inflatable cuff 10 embracing the shaft 1. The cuff 10 is of the high- volume/low-pressure kind so that it has a relatively floppy shape when deflated but, when inflated, it fills out at low pressure to a diameter matching the internal diameter of the trachea "T". The cuff 10 is moulded mainly from a conventional plastics material such as PVC or polyurethane. The cuff 10 is attached to the shaft 1 at opposite ends over an opening 11 on the outer surface of the shaft into an inflation lumen 12 extending along the shaft within its wall thickness. The inflation lumen 12 is connected towards the rear end of the tube with a small-bore inflation line 13 that is terminated by a combined inflation indicator, valve and connector 14.

At its machine end 7 the tube has a flange 20, to which a neck strap (not shown) is attached, and a standard 15mm female coupling 21.

As so far described, the tube is conventional.

The tube differs from existing tubes in that the outer surface of the sealing cuff 10, or at least a major part of the cuff that contacts the surface of the tracheal wall, includes an active substance effective to reduce damage to the trachea. This active substance is preferably provided by a coating 30 on the outer surface of the cuff 10 but could,

alternatively, be provided by incorporating the substance within the matrix of the plastics material forming the cuff. The coating 30 is shown as being applied to a localised region 31 of the cuff that comes into contact with the tracheal wall in use but could instead be applied over the entire surface of the cuff 10. The coating need not be continuous but could be in the form of a pattern of discrete areas, such as spots or bands. The substance of the coating 30 preferably includes an anti-proliferative agent, that is, an agent effective in reducing the risk of pressure injury stenosis or narrowing of the tracheal passage. The anti-proliferative coating 30 could include drugs or analogues such as immunosuppressants (for example Rapamycin, a derivative of Sirolimus) dissolved into a delivery agent. When the cuff 10 contacts the wall of the trachea T the drug is delivered locally to the wall of the blood vessels in the region so as to help limit the growth of scar tissue. The coating 30 could be applied to the cuff 10 by spray coating, dip coating or vacuum C0 ₂ deposition. The delivery agent with which the active agent is combined could be a polymer, such as a bio-degradable or bio- resorbable material, such as Polylactide co-glycocide (PLA) or a non-bio-degradable polyurethane based elastomer. This mixture could be dissolved into a suitable organic high vapour pressure solvent before application to the surface of the cuff 10. The mixture of the polymer and active agent acts to control the release kinetics of the agent allowing it to be released or eluted over the desired time- frame, such as hours, days or weeks thereby inhibiting the formation of cell masses over this period of time.

The invention is not confined to use on sealing cuffs inflated by a gas but could be used with foam cuffs, sealing flanges or any other sealing means that contacts the surface of the trachea. The invention could be used in any tracheal tube, not just tracheostomy tubes, and is not limited to tubes for human use but could be used on veterinary tracheal tubes.