This invention relates to tracheal tubes of the kind having a shaft of a silicone material, a patient end portion of the shaft being adapted to extend into die body and a machine end portion of the shaft being adapted to project outwardly of the body.

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 by means of a flange fixed with the machine end of the tube and positioned to extend outwardly on opposite sides of the tube.

Tracheostomy tubes can be made of various materials and are usually of a bendable plastics material such as PVC, polyurethane or silicone. Silicone tubes are particularly advantageous for long-term use because they can be highly flexible, making them less traumatic and damaging to tissue contacted by the tube. The silicone material is also highly compatible with patient tissue with a very low risk of granulation. Another advantage of silicone is that it is resistant to high temperatures, which enables it to be repeatedly autoclaved and reused. The soft nature of silicone tubes, however, means that they can be easily kinked and occluded by external pressure unless measures are taken to avoid this. Often, silicone tubes are reinforced by means of a stiff helical member extending along the tube, either along substantially their entire length or along only a part of the length.

Typically, the reinforcement member is a metal wire. Although metal wire reinforcements are ideal to give the degree of kink and crush resistance desired they have the disadvantage of not being entirely compatible with MRI (magnetic resonance imaging) equipment or being only MRI conditional.

It has been proposed to use reinforcements made of non-ferromagnetic metals but there is reluctance to use even these materials, especially with higher resolution MRI equipment with field strengths of between 6T and 10T. MRI conditional materials may not cause a danger to the patient but they can lead to distortion of the magnetic field and cause image artefacts.

It has also been proposed to use stiffer plastics filaments, such as of nylon or aramid, as the helical reinforcement of silicone tubes. These can provide some degree of

reinforcement although not as much as metals. These plastics have a further disadvantage that they are often not as heat resistant as silicone so they can be prone to damage by the high temperatures met during autoclave treatment.

It is known for tracheal tubes to have a machine end portion of the shaft extending outwardly beyond the point where the tube enters the body. A silicone paediatric

tracheostomy tube sold by Smiths Medical under the Bivona® FlexTend™ trade mark (Bivona is a Registered Trade Mark of Smiths Medical) has such a machine end portion extending outwardly beyond the supporting flange. This tube is reinforced with a helical metal wire and is terminated by a connector by which connection is made to the tube.

Because the machine end portion extends freely outside the body and is connected to breathing tubing it would be particularly prone to kinking if not reinforced.

Examples of reinforced tracheal tubes are described in, for example, GB2552250, GB933307, US5906036, WO2010/089523, EP1078645, WO2015075412, WO08083286, US6148818, US5546936, US5429127, EP0950424, EP2644221, US5628787, US4737153, US2012/0118294, US4990143, US5181509, US2007083132, US8783254, US6130406, US6017335 and DE867144.

It is an object of the present invention to provide an alternative reinforced tracheal tube. According to the present invention there is provided a tracheal tube of the above- specified kind, characterised in that the machine end portion is reinforced along at least a part of its length by an elongate silicone member wrapped helically around the machine end portion and secured with its outer surface.

The elongate member preferably includes a hollow tube, which may be filled with a silicone material. The silicone material filling the hollow tube may be allowed to vulcanise while wrapped around the machine end portion. The elongate silicone member may have a circular section. The elongate silicone member may have an outer diameter of approximately 2.5mm. The silicone material of the elongate member is preferably slightly harder than the silicone of the shaft. The shaft may be made of a material having a Shore A hardness of between 60 and 70 and the elongate member being made of a material having a Shore A hardness of approximately 80. The elongate member is preferably wrapped tightly around the outside of the machine end portion with adjacent turns in contact with one another. The elongate member may be secured with the outer surface of the machine end portion by bonding using a liquid silicone. The shaft may be terminated at its machine end by a male tapered connector. The tube may be a tracheostomy tube such as a paediatric tracheostomy tube.

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

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

Figure 2 is an enlarged cross-sectional, side elevation view of a part of the machine end portion of the tube of Figure 1.

The tracheostomy tube 1 has a curved shaft 10 of circular section formed from a flexible silicone material having a durometer (Shore A) between 60 and 70. The dimensions of the tube are selected to be suitable for use in paediatric or neonatal patients. The shaft 10 has a patient end 12 adapted to be located within the trachea of the patient and has a conventional sealing cuff 13 towards its patient end.

The machine end 14 of the shaft 10 is adapted, during use, to be located externally of the tracheostomy opening formed in the patient’s neck. The machine end 14 of the shaft 10 is bonded with a hub or connector 15 having a conventional 15mm male tapered outer surface 16. The connector 15 is adapted to make a removable push fit in a conventional 15mm female connector (not shown) at one end of a breathing tube extending to a ventilator or anaesthetic machine. Alternatively, the machine end of the tube 1 could be left open to atmosphere when the patient is breathing spontaneously. The tracheostomy tube 1 also includes a radially-extending support flange 20 adapted to lie against the skin surface of the neck on either side of the tracheostomy stoma. The flange 20 is moulded integrally with the shaft 10 about midway along its length or it could be a separate component. The flange 20 has openings (not shown) at opposite ends for attachment to a neck strap (not shown) used to support the tube with the patient’s neck. The flange 20 divides the shaft 10 into a patient end portion 22, adapted to extend through die tracheostomy and locate in the trachea, and a machine end portion 23 that projects rearwardly, outwardly of the tracheostomy and extends freely. This machine end portion 23 provides a flexible connection of the connector 15 with the patient end portion 22 so that the tracheostomy is isolated to some extent from the connector. This enables connection to and disconnection from the connector 15, or repositioning of the connector, to be made with less force being transmitted to the tracheostomy tissue, thereby reducing trauma and discomfort.

It will be appreciated that the tube could have a different size or shape according to the application.

The sealing cuff 13 is inflated and deflated by means of an inflation line 30 terminated at one end by a conventional combined inflation indicator and an MRI- compatible valved connector 31. The other end of the inflation line 30 is connected to an inflation lumen 33 extending along one side of the patient end portion 22 of the shaft 10, in the region of the flange 20. The silicone material from which the shaft 10 is made has various advantages. It is highly flexible, very compatible with patient tissue and is resistant to the high temperatures used during autoclave heat treatment. The flexible nature of the material, however, means that the machine end portion 23 would be prone to kinking unless steps were taken to prevent this. Present silicone tubes with this configuration therefore usually have their machine end portion reinforced by a helical metal wire. Such an arrangement prevents this portion kinking without substantially reducing its flexibility. The metal wire, however, means that the tube is not compatible with MRI equipment. Even where the reinforcing metal wire is non-ferromagnetic it may still cause distortion of the MRI image, especially at higher field strengths.

In the arrangement of the present invention the machine end portion 23 of the shaft 10 is reinforced by an elongate silicone member 40 wrapped helically around the outside of the machine end portion and secured to its outer surface. The reinforcing member is in the form of a silicone tube 40 of circular section with a relatively small outer diameter of around 2.5mm. The tube 40 may be identical to the tubing used for the inflation line 30 and is slightly harder than the silicone of the shaft 10, having a durometer (Shore A) of around 80. The tube 40 extends helically, tightly around the outside of the machine end portion 23 with adjacent turns in contact or closely spaced from one another. The reinforcing tube 40 preferably extends along the entire length of the machine end portion 23 from the flange 20 to the machine end connector 15. The tube 40 is bonded to the outside of the machine end portion 23 by a room temperature vulcanising (RTV) liquid silicone applied to the outside of the shaft portion before the tube is wound on, the tube being held in place until vulcanisation has been completed.

The reinforcing tube 40 increases the overall outer diameter of the machine end portion 23 but, because this portion does not extend in the patient, it is not a problem. The reinforcement tubing 40 enables the machine end portion 23 to flex freely with a low risk of kinking. Because the reinforcement 40 is made of the same material (although of a different grade) as the main part of the shaft 10 it bonds well with the shaft. It is also resistant to autoclave temperatures thereby enabling the tube 1 to be autoclaved after use and reused. This helps reduce the cost of maintaining a patient with a tracheostomy tube and also reduces the cost arid environmental damage caused by disposal of clinical waste. The reinforcement 40 enables the tube 1 to be used safely in MRI environments, even those with high field strengths.

The silicone reinforcement need not be a hollow tube. It could instead be a solid elongate member. In one alternative embodiment the reinforcement could be provided by a silicone tube filled with an RTV silicone that is allowed to vulcanise to form a solid rod. Vulcanisation could be arranged to take place while the tube is wrapped around the machine end portion of the main shaft so that the reinforcing component takes on a helical set. The silicone reinforcement need not have a circular section but could, for example, be oval, square or rectangular. The silicone reinforcement need not extend along the entire length of the machine end portion 23 but could just extend along a part of its length.

The invention is particularly advantageous in paediatric size tubes because the small diameter shafts in such tubes makes them more prone to kinking but is not confined to paediatric sizes.