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 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. <CIT> describes a tracheostomy tube having a mounting flange and a detachable connector that can be fitted on the patient end of the tube. Each of <CIT>, <CIT> and <CIT> discloses a tracheostomy tube comprising a shaft and a flange mounted on the shaft, the flange having two radial arms for securing the tube to the neck of a patient, said flange being separately formed from the shaft.

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 shaft and has two radial arms adapted to receive ends of a neck tie by which the tube is secured around the neck, and 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:.

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 and reinforced along its length by an embedded helix <NUM> (<FIG>) of a stiff material such as a metal or hard plastics. 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 externally of the patient and is terminated by a conventional externally tapered connector <NUM> 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 <NUM> extends through a tracheostomy opening in the neck of the patient and supports a mounting flange <NUM> 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 <NUM> projecting externally from the mounting flange <NUM> as is common in paediatric tracheostomy tubes, to help isolate the connector <NUM> 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 <FIG> and <FIG>, the shaft <NUM> includes an enlarged boss <NUM> moulded integrally with the shaft as a single piece and projecting radially externally of the shaft about midway along its length. The boss <NUM> has a generally cylindrical outer surface <NUM> of circular section with an annular step <NUM> to a short forward or patient end region <NUM> of reduced diameter. The external surface <NUM> of the boss <NUM> is interrupted by a pair of alignment formations or ribs <NUM> (only one of which is visible) positioned diametrically opposite one another. The alignment formations <NUM> extend longitudinally of the boss <NUM> from its forward end as far as the step <NUM> with the reduced diameter region <NUM>. The alignment formations <NUM> present a rectangular shape at their outer end and taper slightly outwardly to a smaller width. The two alignment formations <NUM> are aligned along an axis extending orthogonally of the plane of curvature of the shaft <NUM>. The boss <NUM> is completed by a first two mechanical retaining formations in the form of lugs <NUM> located close to and on the machine side of the step <NUM> with the reduced diameter region <NUM>. The lugs <NUM> are rectangular and extend circumferentially by about <NUM>°. The lugs <NUM> project radially outwardly by a distance substantially equal to or slightly less than the height of the alignment formations <NUM>. The outer end of the lugs <NUM> are at a radial distance that exceeds the internal radius of the collar <NUM> at its rear or machine end.

The mounting flange <NUM> is shown most clearly in <FIG>. The flange <NUM> comprises a unitary, single-piece moulding of a soft, deformable plastics such as silicone. The flange <NUM> may be of the same material as the shaft <NUM> or it may be of a different material or of a different grade of the same material. The flange <NUM> has a central circular collar <NUM> from which project two radial arms <NUM> and <NUM>, diametrically opposite one another. The collar <NUM> is about three times the thickness of the main part of the arms <NUM> and <NUM> 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 <NUM> and <NUM> have thickened regions <NUM> within each of which there is an opening <NUM> extending through the flange <NUM>. The openings <NUM> 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 <NUM> is moulded internally with two alignment slots <NUM> extending axially and tapered radially to a smaller width outwardly and having the same shape and size as the alignment formations <NUM> on the shaft <NUM>. The slots <NUM> open at the rear end of the collar <NUM> and extend along the length of the collar as far as an internal annular step <NUM> approximately level with the rear surface of the arms <NUM> and <NUM>. The collar <NUM> is thickened to accommodate the depth of the alignment slots <NUM> in the region of these slots. The collar <NUM> is also formed internally with a second two retaining formations in the form of recesses <NUM> of the same shape and size as, or slightly larger than, the retaining lugs <NUM> on the shaft <NUM>. The recesses <NUM> are located diametrically opposite one another and midway between the two alignment slots <NUM>. The retaining recesses <NUM> are located forwardly within the collar <NUM> adjacent the internal step <NUM>. The shape, dimensions and positioning of the lugs <NUM> on the shaft <NUM> and the recesses <NUM> in the collar <NUM> are such that the lugs fit snuggly in the recesses when the step <NUM> on the boss <NUM> lies in contact with the step <NUM> in the collar. The shaft <NUM> is permanently secured with the mounting flange <NUM> by means of a bonding substance applied between the contacting surfaces on the outside of the boss <NUM> and the inside of the collar <NUM>. The bonding substance could be of any conventional kind such as a solvent, adhesive or glue.

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.

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

Claim 1:
A tracheostomy tube (<NUM>) including a shaft (<NUM>) and mounting flange (<NUM>) on the shaft, the mounting flange (<NUM>) being separately formed from the shaft (<NUM>) and having two radial arms (<NUM> and <NUM>) adapted to receive ends of a neck tie by which the tube is secured around the neck, and a retaining collar (<NUM>) embracing the shaft (<NUM>), characterized in that
the shaft (<NUM>) includes a first retaining formation (<NUM>) at the location of the flange (<NUM>), and
the collar (<NUM>) has a second retaining formation (<NUM>) on an inner surface with which the first formation (<NUM>) on the shaft (<NUM>) is engaged such as to restrict longitudinal movement of the shaft (<NUM>) relative to the collar (<NUM>), that the collar (<NUM>) is deformable to allow it to be stretched outwardly to enable the first and second retaining formations (<NUM> and <NUM>) to be engaged with one another, and that the shaft (<NUM>) is secured with the flange (<NUM>) by a bond between the outside of the shaft (<NUM>) and the inside of the collar (<NUM>).