WO2018134548A1

WO2018134548A1 - Medico-surgical tubes and their manufacture

Info

Publication number: WO2018134548A1
Application number: PCT/GB2017/000182
Authority: WO
Inventors: Timothy Bateman; Stephen James Field; Andrew Thomas Jeffrey
Original assignee: Smiths Medical International Limited
Priority date: 2017-01-18
Filing date: 2017-12-22
Publication date: 2018-07-26
Also published as: GB201700843D0

Abstract

The shaft (1) of a tracheostomy tube is formed by an elongate reinforcement element (10) of a stiff plastics or metal wound around the shaft and formed into loops (11) that are linked together such as by knitting. Alternatively, the shaft may be formed by linked rings (20) or (30). The shaft (1) is sealed by a flexible plastics layer (12) on the inner or outer surface of the reinforcement element.

Description

MEDICO-SURGICAL TUBES AND THEIR MANUFACTURE

This invention relates to medico-surgical tubes of the kind including a shaft having a patient end adapted for location in the body and a machine end adapted for location outside the body.

Tracheostomy tubes are used to enable ventilation or respiration of a patient. The tube is 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 tracheostomy tubes are presently available to suit different needs. Tracheostomy tubes are also available including an inner cannula so that this can be removed and replaced periodically to prevent the build-up of secretions and 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 carried out in emergency situations.

Tracheostomy tubes are usually made by extruding a shaft and then post forming to the desired shape. It can be difficult to ensure tight tolerances and to control the length of a tube accurately when it is extruded. Alternatively, tracheostomy tubes can be moulded, which allows for tighter control of tolerances. In order to provide the range of sizes and shapes of tubes needed by the clinician, and the fixed or adjustable flange versions, multiple mould cavities and tooling are needed, thereby adding to the cost of manufacture. It is also difficult to provide a tracheostomy tube with the strength needed to resist the pressure from the tracheal cartilage rings without collapsing and that is also sufficiently flexible to reduce damage caused to the tracheal lining during insertion and use. It can also be advantageous, especially with inner cannulae of tracheostomy tubes, for the wall of the tube to be as thin as possible to enable maximum airflow and still resist kinking and deformation. There are various other medico-surgical tubes where it is advantageous for the tube to be flexible but also resist crushing forces

It is an object of the present invention to provide an alternative medico-surgical tube and method of manufacture. According to one aspect of the present invention there is provided a tube of the above-specified kind, characterised in that the shaft includes one or more reinforcing elements flexibly linked with one another or itself around the shaft such as to enable the shaft to bend, and that a layer of a flexible sealing material on the or each reinforcing element provides a sealed shaft.

The reinforcing element or elements may be elongate and extend circumferentially around the shaft and may be linked together by weaving, knitting or braiding. Alternatively, the reinforcement elements may be provided by multiple rings.

The or each reinforcement element is preferably of a stiff plastics or metal that is stiffer than the layer of flexible sealing material. The reinforcement element or elements may be a wire of a stiff plastics or metal. The flexible sealing material is preferably a layer of a flexible plastics material along the shaft on the inside or outside of the or each reinforcement element or both. The tube may be a tracheostomy tube.

According to another aspect of the present invention there is provided a method of manufacturing a medico-surgical tube including the steps of flexibly linking together one or more reinforcement elements around the tube to provide a flexible shaft, and providing a layer of flexible plastics material to the or each reinforcement element before or after linking.

The or each reinforcement element may be elongate and the method may include the steps of winding one or more elongate reinforcement elements circumferentially and flexibly linking turns of the or each element together to provide the flexible shaft. The or each reinforcement element may be linked by weaving, knitting or braiding.

According to a further aspect of the present invention there is provided a tube made by a method according to the above other aspect of the present invention. An outer tube for use in a tracheostomy and a method of manufacture, according to the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is side elevation view of the tube;

Figure 2 illustrates in greater detail linked sections of the tube;

Figure 3 is a perspective view of an alternative reinforcing arrangement; and

Figure 4 shows a modification of the arrangement of Figure 3.

With reference to Figures 1 and 2, the tube has a shaft 1 with an inflatable sealing cuff 2 close to its patient end 3, and a flange 4 and connector 5 at its machine end 6. A small bore inflation tube 7 extends along the shaft 1 opening at its patient end into the cuff 2 and being connected with a combined connector and inflation indicator 8 at its opposite end.

The shaft 1 is made up of one or more elongate reinforcing elements 10 extending helically and circumferentially around the shaft. Turns of the or each element 10 are flexibly linked with one another in a manner that enables the different turns of the elements to move relative to one another. The or each elongate element 10 is preferably of a stiff and strong plastics or metal material. The or each element 10 may be of a flat section resembling a strip or it could be of a square, circular or any other shape section. As shown in Figure 2, in one example, different turns of the reinforcing element 10 are formed into loops 11 and are intertwined or knitted with one another to form an arrangement resembling chainmail. The element could be provided in an initially straight shape and formed into the loops during the winding process. Alternatively, the element could be preformed into the undulating loops 11. There are various techniques by which the reinforcing elements 10 or different turns of the same element can be linked with one another, such as by weaving, knitting or braiding. By itself, such an arrangement of linked reinforcement elements would have a relatively porous structure so, it would usually be necessary to make the shaft gas-tight, such as by coating the tube of linked reinforcing elements with an inner or outer layer 12, or both, of a plastics material, or by forming such a layer in some other way, such as by heat shrinking. The reinforcing element or elements could be wound and interlinked on top of a pre-formed inner sleeve on a mandrel and could be given an outer flexible layer, such as by dipping, extrusion, spraying, painting or the like.

This linked element arrangement can give a high resistance to radial or lateral crushing from forces within the tracheal stoma and protect against kinking and collapse with a relatively thin wall, whilst still providing sufficient flexibility to conform to the tracheal anatomy.

In an alternative arrangement, the reinforcing elements could be provided in the manner shown in Figure 3, by multiple rings 20 connected together. These rings could be of metal or plastic and could be circular, square or of other shapes. Figure 4 shows a ring arrangement where the rings 30 have an internal lug 31 to reduce longitudinal compression.

The tube need not have a fixed flange but could have a flange that is adjustable along the length of the shaft. The high strength construction of the tube enables flanges that grip the tube to be used since the shaft would be resistant to deformation by such a flange.

The invention could be used in both outer tracheostomy tubes, in inner tracheostomy cannulae and in assemblies including both an outer tube and an inner cannula.

The invention could be used to produce tubes with a thinner wall but with similar strength to thicker tubes of a conventional construction. This enables tubes with a higher internal/external diameter ratio to be made, or enables tubes to be made with a standard wall thickness but having greater flexibility. This could be particularly useful in inner cannulae. A larger internal diameter enables a higher gas flow through the tube.

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

Claims

1. A medico-surgical tube including a shaft (1) having a patient end (3) adapted for location in the body and a machine end (6) adapted for location outside the body, characterised in that the shaft (1) includes one or more reinforcing elements (10, 20, 30) flexibly linked with one another or itself around the shaft such as to enable the shaft to bend, and that a layer (12) of a flexible sealing material on the or each reinforcing element (10, 20, 30) provides a sealed shaft (1).

2. A tube according to Claim 1 , characterised in that the reinforcing element or

elements (10) are elongate and extend circumferentially around the shaft (1).

3. A tube according to Claim 2, characterised in that the or each reinforcing elements (10) are linked together by weaving, knitting or braiding.

4. A tube according to Claim 1 , characterised in that the reinforcement elements are provided by multiple rings (20, 30).

5. A tube according to any one of the preceding claims * characterised in that the or each reinforcement element (10, 20, 30) is of a stiff plastics or metal that is stiffer than the layer (12) of flexible sealing material.

6. A tube according to Claims 5 and Claim 2 or 3, characterised in that the

reinforcement element or elements (10) is a wire of a stiff plastics or metal.

7. A tube according to any one of the preceding claims, characterised in that the flexible sealing material is a layer (12) of a flexible plastics material along the shaft (1) on the inside or outside of the or each reinforcement element or both (10, 20, 30).

8. A tracheostomy tube according to any one of the preceding claims.

9. A method of manufacturing a medico-surgical tube including the steps of flexibly linking together one or more reinforcement elements (10, 20, 30) around the tube to provide a flexible shaft (1), and providing a layer (12) of flexible plastics material to the or each reinforcement element (10, 20, 30) before or after linking.

10. A method according to Claim 9, characterised in that the or each reinforcement

element (10, 11) is elongate, and that the method includes the steps of winding one or more elongate reinforcement elements (10) circumferentially and flexibly linking turns of the or each element together to provide the flexible shaft (1).

11. A method according to Claim 10, characterised in that the or each reinforcement element (10) is linked by weaving, knitting or braiding.

12. A tube made by a method according to any one of Claims 9 to 11.