This invention relates to tracheostomy tube assemblies of the kind including an outer tracheostomy tube and an inner cannula arranged to be fitted within and removable from the tracheostomy tube, the tube including a shaft with a patient end adapted for location in the trachea and a machine end portion adapted for location outside the patient, the machine end portion including a male externally tapered connector portion adapted to receive a female connector.

Tracheostomy tube assemblies commonly include an outer tube and an inner tube or cannula that is a removable fit within the outer tube. The inner cannula can be removed and replaced periodically to ensure that the passage through the assembly does not become blocked by secretions. This avoids the need to remove the outer tube so often.

It is important to be able to check readily whether or not an inner cannula is inserted in a tracheostomy tube. At present, this can only be done by removing the female connector of the breathing circuit from the male 15mm connector at the end of the tracheostomy tube because this conceals the machine end of the inner cannula. It has been proposed in US20140014095 for a tracheostomy assembly to include some form of indicator system and display to detect the presence of in inner cannula and give an indication of this. It is important, however, for the tracheostomy assembly and inner cannula to be of low cost so that they can be disposed of after a single use.

It is an object of the present invention to provide an alternative tracheostomy tube assembly and inner cannula.

According to one aspect of the present invention there is provided a tracheostomy tube assembly of the above-specified kind, characterised in that the outer tube includes an indicator portion located towards the patient end of the machine end portion at a position where it is not covered by the female connector fitted on the male connector portion, that the indicator portion is transparent, at least in part, that the inner cannula has a machine end portion for location in the machine end portion of the outer tube, and that the machine end portion of the inner cannula has a part at least conspicuously marked and adapted for location within the transparent part of the indicator portion such that the presence of the inner cannula in the assembly can be readily determined by observation of the indicator portion without the need to remove any mated connector.

The indicator portion of the tracheostomy tube may have an inner surface conspicuously marked in a contrasting manner to the marking on the inner cannula such that when no inner cannula is present the marking on the inner surface of the indicator portion is visible through the transparent part of the indicator portion. The transparent part of the indicator portion is preferably magnifying. The transparent part may have a convex surface on a window of transparent material in the indicator portion. The marking on the inner cannula may be provided by an enlarged ring of a deformable material extending around the cannula such that the ring is compressed into close contact with the inside of the transparent part of the indicator portion. The transparent part of the tracheostomy tube may have warning markings of the same colour as a part at least of the conspicuous markings on the inner cannula such that the warning markings are visible when the inner cannula is absent and are less visible when the inner cannula is present.

According to another aspect of the present invention there is provided a tracheostomy tube for an assembly according to the above one aspect of the invention.

According to a further aspect of the present invention there is provided an inner cannula for an assembly according to the above one aspect of the invention.

A tracheostomy tube assembly including an inner cannula, both in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, which are not to scale, and in which:

Figure 1 is a side elevation view of a tracheostomy tube assembly including an inner cannula inserted in place in the tube; Figure 2 is an enlarged^ side elevation view of the machine end of the tracheostomy tube without an inner cannula inserted;

Figure 3 is a cross-sectional view of the machine end of the tracheostomy tube without an inner cannula inserted along the line ΙΠ-ΙΠ of Figure 2;

Figure 4 is a side elevation view of the inner cannula;

Figure 5 is a side elevation view of the machine end of a modified form of

tracheostomy tube without an inner cannula inserted;

Figure 6 is a side elevation view of a modified form of inner cannula; and

Figure 7 is a side elevation view of the machine end of the tube shown in Figure 5 with the inner cannula of Figure 6 inserted within it.

With reference first to Figures 1 to 4, the tracheostomy tube assembly 1 comprises an outer tracheostomy tube 10 and a removable inner cannula 20 inserted within the outer tube. The outer tube 10 has a curved shaft 11 with a forward, patient end 12 adapted for location within the trachea and a rear, machine end 13. The outer tube 10 typically has an internal diameter between about 2mm and 10mm, and its length could be between 60mm and 200mm. The rear or machine end 13 of the outer tube 10 has a machine end portion or hub 16 and flange 17 to which a retaining tape (not shown) can be fastened for securing the tube with the patient's neck. The machine end portion 16 projects from the machine side of the flange 17 and has a connector portion 18 at its machine end formed with a tapered external surface 19 with a reduced diameter at its machine end. This tapered surface 19 provides a 15mm male connector adapted to mate with a cooperating female connector 3 at the end of breathing tubing 4. The forward or patient end of the machine end portion 16 provides an indicator portion 22, which is described in detail later. The length of the connector portion 18 exceeds that necessary to receive the female connector 3 in a full mating engagement, which is indicated as being fully engaged with the male connector portion in Figure 1 by the broken lines. This ensures that the indicator portion 22 is not covered by the mated connector 3 but is exposed to view beyond the forward or patient end of the connector.

The indicator portion 22 shown in Figures 1 to 3 includes one or more rectangular windows 24 formed of a clear optically-transparent plastics material within the wall of the otherwise opaque or translucent machine end portion 16. Preferably there are several windows 24 spaced around the tube 10 so that at least one window is visible at any point around the tube. The inside surface 25 (Figure 3) of the indicator portion 22 is formed with a conspicuous marking, such as a coloured band 26 of a warning colour extending around the indicator portion. The coloured band 26 is visible externally through the or each window 24 when the inner cannula 20 is not present, as shown in Figure 2, so that the user of the tube 10 is alerted to the fact that the tube does not contain an inner cannula.

With reference now also to Figure 4, the inner cannula 20 includes a shaft 200 of circular section having at its rear or machine end an end fitting or machine end portion 201. The shaft 200 is of a thin, stiff plastics material, such as PVC, polyurethane, polyethylene, polypropylene, PTFE or other flexible or semi-rigid plastics material. The external diameter of the shaft 200 is selected to be just smaller than the outer tube 10 so that the inner cannula 20 can be readily inserted and removed from the outer tube. The machine end portion or fitting 201 is shaped to locate within the hub 16 of the tracheostomy tube 1. The machine end portion 201 and has a hinged ring-pull formation 203 at its machine end, which is accessible at the rear end of the hub 16 of the outer tube 10 when the inner cannula 20 is fully inserted and by which the inner cannula can be pulled out of the outer tube. The inner cannula 20 differs from previous inner cannulae by having a part 204, which is conspicuously marked in some way, such as by a high visibility colour, a pattern or a legend. In particular, and as shown in Figure 4, this part 204 may take the form of an enlarged, brightly coloured ring of a compressible material, such as a soft elastomeric material mounted on and extending completely around the outer surface of the inner cannula 20. The ring 204 is located just forwardly, to the patient side, of the machine end fitting 201 in a position where it will align with the or each window 24 in the indicator portion 22 of the outer tube 10 when the inner cannula 20 is fully inserted in the outer tube. The natural external diameter of the ring 204 is selected to be just larger than the internal diameter of the outer tube 10 so that the ring is compressed radially slightly when inserted in the outer tube. This ensures that there is an intimate optical contact between the outside of the marked ring 204 and the inside of the or each window 24 so that the maximum amount of ambient light incident on the window is reflected from the marked surface of the ring. Where the ring 204 is conspicuously coloured this causes the entire window 24 to take on the colour of the ring. It is, therefore, readily apparent whether or not an inner cannula 20 is inserted in the outer tube 10, simply by glancing at the indicator windows 24. By spacing the window or windows 24 around the outer tube 10 the presence of the inner cannula 20 can be confirmed at all positions around the tube. It will be appreciated that, because the indicator 22 is located forwardly of the forward end of the female connector 3 mated with the outer tube 10, the presence of the inner cannula 20 can be confirmed with the female connector fitted, thereby avoiding the need to remove the connector and disconnect the patient from the supply of ventilation gases.

The indicator marking on the inner cannula need not be in the form of a conspicuous colour but could instead, or additionally, incjude conspicuous marks or legends, such as to indicate the size of the inner cannula. The marking on the inner cannula could be arranged to interact with marking on the indicator of the outer tube. For example, as shown in Figure 5, the indicator 122 on the outer tube 110 is printed with warning symbols 123 of the same colour as the indicator ring around the inner cannula (not shown). The indicator 122 on the outer tube 110 is shown as being in the form of a bezel extending around the entire circumference of the tube and having a convex, magnifying outer surface 124 to make the indicator more prominently visible at different positions. The warning symbols 123 around the outer tube indicator 122 are illustrated as being explanation marks "!" but could take any other form. The marks 123 are readily visible when no inner cannula is present (as a warning of the absence of the inner cannula) but, because they are of the same colour as the ring on the inner cannula, the markings become invisible (or less visible) when the inner cannula is inserted. This causes the background against which the markings are viewed to change to being the same as the markings themselves, thereby reducing their contrast and visibility.

There are many possible variations of the marking arrangements on the inner cannula and outer tube to make it obvious to the user whether or not an inner cannula is inserted. For example, the marking 123 on the indicator 122 shown in Figure 5 could be printed in black. The inner cannula 120 used in such an outer tube is shown in Figure 6 as having an enlarged, deformable indicator ring 104 of a conspicuous colour but interrupted with black regions B at the same spacing around the cannula as the markings around the outer tube 110. Before the inner cannula 120 is inserted in the outer tube 110 the markings 123 on the outer tube are clearly visible as a warning that no inner cannula is present. When, however, the inner cannula 120 is inserted, as shown in Figure 7, the black regions B on the ring 104 of the inner cannula lie under the black markings 123 on the outer tube 110, thereby making the warning markings on the outer tube become invisible, or less visible. The transparent indicator bezel 122 around the outer tube 110 now shows a series of coloured C and black B regions to indicate that the inner cannula 120 is present.