This invention relates to tracheostomy tubes of the kind including a shaft with a mounting flange on the shaft.

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 towards 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. The flange may be moulded as an integral, single piece with the shaft of the tube. Alternatively, the flange may be moulded as a separate component from the shaft and subsequently assembled on and bonded to the shaft. This assembly and bonding process can be time consuming and lead to high manufacturing costs.

It is an object of the present invention to provide an alternative tracheostomy tube and a method of assembling such a tube.

According to one aspect of the present invention there is provided a tracheostomy tube of the above-specified kind, characterised in that the shaft includes a first retaining formation at the location of the flange, that the mounting flange is separately formed from the flange and has a retaining collar embracing the shaft, that the collar has a second retaining formation on an inner surface with which the first formation on the shaft is engaged such as to restrict longitudinal movement of the shaft relative to the collar, that the collar is deformable to allow it to be stretched outwardly to enable the first and second retaining formations to be engaged with one another, and that the shaft is secured with the flange by a bond between the outside of the shaft and the inside of the collar.

The first retaining formation on the shaft is preferably a projecting lug and the second retaining formation on the collar is preferably a recess. The shaft may have two retaining formations arranged diametrically opposite one another on the shaft, and the flange may have two retaining formations on the collar with which the respective retaining formations on the shaft are received. The shaft may additionally include one or more longitudinally extending alignment formations on its outer surface, the collar on the flange additionally including cooperating alignment formations on its inner surface. The machine end of the shaft is preferably provided with a connector, the retaining formation on the shaft being provided on a boss projecting outwardly of the shaft, and the boss being spaced from both the patient end of the shaft and the connector at the machine end of the shaft so that when the mounting flange is positioned against a patient’s neck a length of shaft projects outwardly of the patient. The mounting flange is preferably of a deformable silicone material. According to another aspect of the present invention there is provided a method of assembling a mounting flange on a shaft of a tracheostomy tube including the steps of providing a shaft including a first retaining formation at the desired location of the flange, providing a separately formed flange having a deformable retaining collar with a second cooperating retaining formation arranged to engage with the first retaining formation, applying a bonding substance to the outside of the shaft in the region of the first retaining formation or the inner surface of the collar or to both, threading the patient end of the shaft through the collar until contact with one of the retaining formations on the shaft prevents further insertion of the shaft in the collar, and deforming the collar outwardly to enable further insertion and to enable the first and second retaining formations to engage one another and thereby retain the flange on the shaft while the bonding substance cures.

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

A paediatric tracheostomy tube with a mounting flange and a method of assembly of the 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 perspective view of the tube;

Figure 2 is a perspective view of the shaft of the tube before the mounting flange is assembled on the shaft;

Figure 3 is a perspective view of the mounting flange before assembly on the shaft; and

Figure 4 is a cross-sectional side elevation view of the tube in the region of the mounting flange. With reference first to Figure 1 the tracheostomy tube 1 has a curved shaft 10 of circular section moulded from a flexible plastics such as silicone and reinforced along its length by an embedded helix 4 (Figure 4) of a stiff material such as a metal or hard plastics. The patient, distal or forward end 12 of the tube 1 is adapted to locate in the trachea. The machine, proximal or rearward end 13 of the tube 1 extends externally of the patient and is terminated by a conventional externally tapered connector 14 forming a male coupling for mating with a cooperating female coupling (not shown) at the end of breathing tubing extending to a ventilator or the like. The shaft 10 extends through a tracheostomy opening in the neck of the patient and supports a mounting flange 30 about half way along its length by which the tube is secured with the patient’s neck. This configuration leaves a length of the shaft 10 projecting externally from the mounting flange 30 as is common in paediatric tracheostomy tubes, to help isolate the connector 14 from the tracheostomy site. In alternative embodiments the flange could be positioned close to the machine end of the shaft, directly adjacent the connector.

As most clearly shown in Figures 2 and 4, the shaft 10 includes an enlarged boss 15 moulded integrally with the shaft as a single piece and projecting radially externally of the shaft about midway along its length. The boss 15 has a generally cylindrical outer surface 16 of circular section with an annular step 17 to a short forward or patient end region 18 of reduced diameter. The external surface 16 of the boss 15 is interrupted by a pair of alignment formations or ribs 19 (only one of which is visible) positioned diametrically opposite one another. The alignment formations 19 extend longitudinally of the boss 15 from its forward end as far as the step 17 with the reduced diameter region 18. The alignment formations 19 present a rectangular shape at their outer end and taper slightly outwardly to a smaller width. The two alignment formations 19 are aligned along an axis extending orthogonally of the plane of curvature of the shaft 10. The boss 15 is completed by a first two mechanical retaining formations in the form of lugs 20 located close to and on the machine side of the step 17 with the reduced diameter region 18. The lugs 20 are rectangular and extend circumferentially by about 20°. The lugs 20 project radially outwardly by a distance substantially equal to or slightly less than the height of the alignment formations 19. The outer end of the lugs 20 are at a radial distance that exceeds the internal radius of the collar 31 at its rear or machine end. The mounting flange 30 is shown most clearly in Figure 3. The flange 30 comprises a unitary, single-piece moulding of a soft, deformable plastics such as silicone. The flange 30 may be of the same material as the shaft 10 or it may be of a different material or of a different grade of the same material. The flange 30 has a central circular collar 31 from which project two radial arms 32 and 33, diametrically opposite one another. The collar 31 is about three times the thickness of the main part of the arms 32 and 33 and projects rearwardly above the rear surface of the arms but lies level with the arms on their forward, patient side. At their outer ends the arms 32 and 33 have thickened regions 34 within each of which there is an opening 35 extending through the flange 30. The openings 35 receive the ends of a neck tie (not shown) or similar article by which the tube is secured about the neck of the patient. The collar 31 is moulded internally with two alignment slots 36 extending axially and tapered radially to a smaller width outwardly and having the same shape and size as the alignment formations 19 on the shaft 10. The slots 36 open at the rear end of the collar 31 and extend along the length of the collar as far as an internal annular step 37 approximately level with the rear surface of the arms 32 and 33. The collar 31 is thickened to accommodate the depth of the alignment slots 36 in the region of these slots. The collar 31 is also formed internally with a second two retaining formations in the form of recesses 38 of the same shape and size as, or slightly larger than, the retaining lugs 20 on the shaft 10. The recesses 38 are located diametrically opposite one another and midway between the two alignment slots 36. The retaining recesses 38 are located forwardly within the collar 31 adjacent the internal step 37. The shape, dimensions and positioning of the lugs 20 on the shaft 10 and the recesses 38 in the collar 31 are such that the lugs fit snuggly in the recesses when the step 17 on the boss 15 lies in contact with the step 37 in the collar. The shaft 10 is permanently secured with the mounting flange 30 by means of a bonding substance applied between the contacting surfaces on the outside of the boss 15 and the inside of the collar 31. The bonding substance could be of any conventional kind such as a solvent, adhesive or glue.

The tube 1 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. The tube is assembled by first moulding the shaft 10 and flange 30 separately. A bonding substance is then applied to either the outside of the boss 15 on the shaft 10 or to the inside of the collar 31 on the flange 30 or to both the boss and collar. The patient end of the shaft 10 is then threaded through the collar 31 from its rear or machine side. The shaft 10 is advanced through the collar 31 until the forward end region 18 of the boss 15 locates in the rear end of the collar. The shaft 10 is twisted as necessary to bring the alignment formations 19 into alignment with the alignment slots 36 in the collar 31 and ensure the correct orientation of the shaft relative to the mounting flange 30. The two retaining lugs 20 now contact the rear end of the collar 31 and impede further free insertion. However, the deformable nature of the collar 31 enables it to be manipulated over the lugs 20 to allow the boss 15 to be inserted in the collar. When the lugs 20 come level with the retaining recesses 38, the collar 31 relaxes about the boss 15 with the lugs received within the recesses. The engaged lugs 20 and recesses 38 serve to prevent any inadvertent longitudinal movement of the shaft relative to the flange, thereby retaining the two components together mechanically while the bonding substance cures. It can be seen that the engagement of the lugs 20 in the recesses 38 also resists rotation between the components 10 and 30 during the bonding process. This means that the assembler does not need to hold the components 10 and 30 together while the bonding substance cures, can release the assembly, and go on to assemble the next tube.

The retaining formations on the shaft and collar need not be provided by a projection on the shaft and a recess on the collar but could, instead, be provided by a recess on the shaft and an engaging projection on the collar. The arrangement with the recess in the collar is preferred because it is easier to remove a flange with such a feature from its mould. The tube could have just one retaining formation on the shaft and collar, or more than the two described.