WO2018215728A1

WO2018215728A1 - Medico-surgical tubes

Info

Publication number: WO2018215728A1
Application number: PCT/GB2018/000072
Authority: WO
Inventors: Timothy Bateman; Andrew Thomas Jeffrey; Christopher John WOOSNAM
Original assignee: Smiths Medical International Ltd
Current assignee: Smiths Medical International Ltd
Priority date: 2017-05-24
Filing date: 2018-04-20
Publication date: 2018-11-29
Anticipated expiration: 2019-11-24
Also published as: GB201708308D0

Abstract

A tracheostomy tube has a plastics shaft (10) with an X-ray marker (30) at its patient end (12). The marker is in the form of a ring of a metal alloy that is x-ray opaque but is non-magnetic so that it is compatible with MRI imaging equipment. The alloy is preferably at least 50% cobalt and 40% of cobalt, chromium, tungsten and nickel.

Description

MEDICO-SURGICAL TUBES

This invention relates to medico-surgical tubes substantially of a plastics material.

Tracheal tubes are used to enable ventilation or respiration of a patient. Endotracheal tubes are inserted to the trachea via the mouth or nose. Tracheostomy tubes are inserted into the trachea via a surgically-formed opening in the neck so that one end locates in the trachea and the other end locates outside the patient adjacent the neck surface. Various types of different tracheal tubes are presently available to suit different needs. Tracheostomy tubes are also available with an inner cannula, which can be removed and replaced periodically to prevent secretions building up and to avoid the need to replace the tube itself. Tracheostomy tubes can be inserted by different techniques, such as the surgical cut-down procedure carried out in an operating theatre or a percutaneous dilatation 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 that extends outwardly on opposite sides of the tube. Tracheal tubes often have a sealing cuff towards their patient end. When inflated the cuff seals between the outside of the tube and the inside of the trachea so that gas flow is confined along the inside of the tube.

It is important to ensure that the patient end tip of the tube is correctly inserted, that is, it is inserted to the correct depth and it is inserted correctly in the trachea and not in the oesophagus. One technique to check for correction insertion is to image the tracheal region with x-rays. The problem with this is that most tubes are made of a plastics material and are transparent to x-rays so do not appear clearly on an x-ray image. Attempts have been made to alleviate this problem by increasing the x-ray opacity of the tube, either of the whole tube or in part. One way of doing this is by incorporating an x-ray opaque filler, such as of barium sulphate, within the plastics of the tube. US5499625 describes a tube with an x-ray opaque stripe interrupted by openings in the tube. US362593, US3725522 and US3755525 describe tubes that are entirely of an x-ray opaque plastics or have an x-ray opaque tip moulded on to the shaft. US3529633 describes a tube of an x-ray opaque material having a transparent stripe along its length. US3042045 and USRE25788 describe tubes with an x-ray opaque stripe. US4657024 describes a tube with an x-ray opaque layer between two outer layers. US3589368 describes a tube with a fused ring of x-ray opaque plastics. US8381730 and US285715 describe tubes with an x-ray opaque line. WO9400174 describes a tube with a bonded tip of an x-ray opaque plastics. GB2329841 describes a tube where the sealing cuff is attached with an x-ray opaque adhesive. GB1513495 describes a tube where the cuff inflation line is closed by a rod of x-ray opaque plastics. EP2648792 describes an

angioplasty balloon including a film of an x-ray opaque material. Other arrangements are described in: US6378523, US6568393, US3190290, US3295527, US3314430, US3605750, GB2328878, US2008230070, US5429617, US9242058 and US8978657.

A problem with these previous tubes using an x-ray opaque plastics material is that such materials are not highly opaque and do not contrast well in an x-ray image against the surrounding anatomy. Although x-ray markers of metal can be highly visible in an x-ray image they have the disadvantage of not being suitable for use in an MRI environment. This is a real problem because a ventilated patient may need an unexpected, emergency MRI examination. If the tube by which the patient is ventilated is not MRI compatible it has to be removed and replaced with one that is compatible, which takes time and delays examination and treatment. This problem is not confined to tracheal tubes but exists with other medico- surgical tubes.

It is an object of the present invention to provide an alternative medico-surgical tube.

According to the present invention there is provided a medico-surgical tube of the above-specified kind, characterised in that the tube includes an x-ray opaque marker including an MRI-compatible metal alloy, and that at least substantially 90% of the alloy is comprised of cobalt, chromium, tungsten and nickel. The alloy preferably comprises at least 50% cobalt and at least 40% comprised of chromium, tungsten and nickel. The marker may be in the form of a ring of the alloy attached with a plastics shaft of the tube towards its patient end. The ring is preferably embedded in plastics material of the shaft so that no part of its surface is exposed.

Alternatively, the marker could be in the form of a slug inserted in a cuff inflation line of the tube to close off the patient end of the inflation line. Alternatively the marker could be provided by a region in the plastics material containing multiple discrete elements of the alloy, such as in the form of particles, flakes or microspheres of the alloy. The medico- surgical tube is preferably a tracheal tube such as a tracheostomy tube.

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 perspective view of the tracheostomy tube; and

Figure 2 is an enlarged cross-sectional view of the patient end of the tube.

With reference first to Figure 1, the tracheostomy tube comprises a curved shaft 10 of circular section with a patient end 12 adapted to be located within the trachea of the patient. The shaft 10 has a conventional sealing cuff 13 towards its patient end, which is inflated by means of an inflation lumen 14 extending along the shaft. The lumen 14 opens at its patient end 15 within the cuff 13 and connects towards its machine end 16 with a small bore inflation tube 17 terminated by a combined inflation indicator and valve 18. The shaft 10 is moulded or extruded and is bendable but relatively stiff, being made of a plastics material such as PVC or silicone. The machine end 20 of the shaft 10 is adapted, during use, to locate externally of the tracheostomy opening formed in the patient's neck. The machine end 20 of the shaft 10 is bonded into a hub or connector 21 having a conventional 15mm male tapered outer surface 22. The connector 21 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 cpuld be left open to atmosphere when the patient is breathing spontaneously. The tracheostomy tube 1 also includes a raclially-extending support flange 23 adapted to lie against the skin surface of the neck on either side of the tracheostomy stoma. The flange 23 has openings 24 at opposite ends for attachment to a neck strap (not shown) used to support the tube with the patient's neck.

With reference now also to Figure 2, the patient end 12 of the shaft 10 includes an x- ray marker 30 in the form of an x-ray opaque ring of a selected metal alloy that is highly opaque to x-rays but is compatible with MRI machines. The ring 30 is circular with an internal diameter slightly greater than the internal diameter of the shaft 10 and an outer diameter slightly less than the outer diameter of the shaft. The ring 30 is set back a small distance, around 1mm, from the patient end 12 of the shaft 10 so that it is entirely embedded in the plastics material of the shaft with no part of its metal surface exposed. The ring 30 could be attached with the shaft in various different ways. For example, the shaft could be extruded, cut to length and then its patient end could be heated to cause it to flow around the ring marker in a suitable mould.

Alternatively, the marker ring could be moulded into a plastics ring that was subsequently attached to the patient end of the shaft. The marker ring could, instead, simply be swaged onto a groove around the outside of the tube. In another arrangement the marker ring could be mounted in a groove adjacent a shallow step on the outside of the tube and overlaid by a collar of the sealing cuff, the step ensure a smooth continuation of the tube with the cuff. The marker could be formed as a helical reinforcement wire extending along the tube or just the patient end of the tube so that it serves the dual purpose of reinforcing the tube and providing an x-ray visible marker.

The marker 30 is made from an alloy predominantly (at least 90%) of cobalt, chromium, tungsten and nickel with smaller amounts of other materials, namely carbon, iron, manganese, phosphorus, silicon and sulphur, not all of which need be present. The alloy may be Cobalt Alloy L-605, which is non-magnetic and corrosion resistant. This alloy has been found to give a clear contrast in an x-ray image. The alloy is also compatible with MRI imaging machines in that the magnetic fields do not induce any significant forces or torques on the marker, do not cause any significant heating of the marker and the marker does not cause any significant distortion of the magnetic fields that could degrade the image produced.

The typical range of % of elements in the L-605 alloy are shown in the table below:

It is not essential that the marker take the form of a ring since it could have other forms. For example, the marker could be in the form of a cylindrical plug or slug bonded into the machine end of the cuff inflation line 14 and serve the dual purpose of both closing the machine end of the inflation line and providing an x-ray patient end marker. Instead of being in the form of a single component the marker could take the form of multiple, discrete elements of the alloy, such as in the form of small particles, flakes or solid microspheres.

The invention is not confined to tracheal tubes but could be used in other medico- surgical tubes.

Claims

1. A medico-surgical tube substantially of a plastics material, characterised in that the tube includes an x-ray opaque marker (30) including an MRI-compatible metal alloy, and that at least substantially 90% of the alloy is comprised of cobalt, chromium, tungsten and nickel.

2. A tube according to Claim 1, characterised in that the alloy comprises at least 50% cobalt and at least 40% comprised of cobalt, tungsten and nickel.

3. A tube according to Claim 1 or 2, characterised in that the marker is in the form of a ring (30) of the alloy attached with a plastics shaft (10) of the tube towards its patient end (12).

4. A tube according to Claim 3, characterised in that the ring (30) is embedded in

plastics material of the shaft (10) so that no part of its surface is exposed.

5. A tube according to Claim 1 or 2, characterised in that the marker is in the form of a slug inserted in a cuff inflation line (14) of the tube to close off the patient end of the inflation line.

6. A tube according to Claim 1 or 2, characterised in that the marker is provided by a region of the plastics material containing multiple discrete elements of the alloy.

7. A tube according to Claim 6, characterised in that the marker is in the form of

particles, flakes or microspheres of the alloy.

8. A tube according to any one of the preceding claims, characterised in that tube is a tracheal tube.

9. A tube according to Claim 8, characterised in that the tube is a tracheostomy tube.