WO2020025911A1

WO2020025911A1 - Tracheal tube and method of making said tube

Info

Publication number: WO2020025911A1
Application number: PCT/GB2019/000097
Authority: WO
Inventors: Stephen James Field
Original assignee: Smiths Medical International Limited
Priority date: 2018-07-28
Filing date: 2019-07-09
Publication date: 2020-02-06
Also published as: GB201812443D0

Abstract

A silicone paediatric tracheostomy tube (1, 101) has a machine end portion (23, 123, 123') reinforced with a thicker wall than its patient end portion (22). The machine end portion has several circumferential rows of recesses (17, 117, 117') in its outer surface to increase the flexibility of the machine end portion. The recesses may be covered by a thin integral extension sleeve (124, 124') formed integrally with the machine end portion (123, 123') that is folded back and bonded to the outside of the machine end portion.

Description

TRACHEAL TUBE AND METHOD OF MAKING SAID TUBE

This invention relates to tracheal tubes of the kind having a shaft with a patient end portion adapted to extend into the body forwardly of a mounting flange and a machine end portion adapted to project rearwardly of the flange away from the patient.

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 by means of a flange fixed with the machine end of the tube and positioned to extend outwardly on opposite sides of the tube.

Tracheostomy tubes can be made of various materials and are usually of a bendable plastics material such as PVC, polyurethane or silicone. Silicone tubes are particularly advantageous for long-term use because they can be highly flexible, making them less traumatic and damaging to tissue contacted by the tube. The silicone material is also highly compatible with patient tissue with a very low risk of granulation. Another advantage of silicone is that it is resistant to high temperatures, which enables it to be repeatedly autoclaved and reused. The soft nature of silicone tubes, however, means that they can be easily kinked and occluded by external pressure unless measures are taken to avoid this. Often, silicone tubes are reinforced by means of a stiff helical member extending along the tube, either along substantially their entire length or along only a part of the length.

Typically, the reinforcement member is a metal wire. Although metal wire reinforcements are ideal to give the degree of kink and crush resistance desired they have the disadvantage of not being entirely compatible with MRI (magnetic resonance imaging) equipment or being only MRI conditional.

It has been proposed to use reinforcements made of non-ferromagnetic metals but there is reluctance to use even these materials, especially with higher resolution MRI equipment with field strengths of between 6T and 10T. MRI conditional materials may not cause a danger to the patient but they can distort die magnetic field leading to image artefacts.

It has also been proposed to use stiffer plastics filaments, such as of nylon or aramid, as the helical reinforcement of silicone tubes. These can provide some degree of

reinforcement although not as much as metals. These plastics have a further disadvantage that they are often not as heat resistant as silicone so they can be prone to damage by the high temperatures met during autoclave treatment.

It is known for tracheal tubes to have a machine end portion of the shaft extending outwardly beyond the point where the tube enters the body. A silicone paediatric

tracheostomy tube sold by Smiths Medical under the Bivona® FlexTend™ trade mark (Bivona is a Registered Trade Mark of Smiths Medical) has such a machine end portion extending outwardly beyond the supporting flange. This tube is reinforced with a helical metal wire and is terminated by a connector by which connection is made to the tube.

Because the machine end portion extends freely outside the body and is connected to breathing tubing it would be particularly prone to kinking if not reinforced.

It is an object of the present invention to provide an alternative reinforced tracheal tube.

According to one aspect of the present invention there is provided a tracheal tube of the above-specified kind, characterised in that the machine end portion has a wall thickness greater than that of the patient end portion and the machine end portion is provided with a plurality of discrete regions disposed along and around the machine end portion recessed into the outer surface of the machine end portion to increase the flexibility of the machine end portion.

The discrete regions may have a rectangular shape and sloping walls. The discrete regions may be arranged in a plurality of circumferential rows and the discrete regions of adjacent rows may be staggered relative to one another. The recesses in the machine end portion may be covered by an outer sleeve. The outer sleeve is preferably formed integrally with the machine end portion, the sleeve being folded forwardly over the discrete regions and bonded to the outer surface of the machine end portion. The tube may include a locking ring assembled on the machine end portion before folding the sleeve forwardly over the locking ring, the locking ring including radially-projecting pins, the sleeve including retaining holes, the pins locating in the holes when the sleeve is folded forwardly over the machine end portion. The tube may include a part of a connector fitted to the locking ring.

According to another aspect of the present invention there is provided a method of making a tracheal tube including the steps of forming a tracheal tube having a shaft with a patient end portion adapted to extend into the body forwardly of a mounting flange and a machine end portion adapted to project rearwardly of the flange away from the patient, the machine end portion having a wall thickness greater than that of the patient end portion, the machine end portion being provided with a plurality of discrete regions disposed along and around the machine end portion recessed into the outer surface of the machine end portion to increase the flexibility of the machine end portion, and an extension sleeve formed integrally as an extension of the machine end portion; folding the extension sleeve forwardly over the outside of the machine end portion to cover the discrete recessed regions in the machine end portion; and bonding the extension sleeve in place along the outside of the machine end portion.

According to a further aspect of the present invention there is provided a tracheal tube made by a method according to the above other aspect of the present invention. The entire tube is preferably made of the same material. The shaft is preferably of a silicone material. The tube may be a tracheostomy tube and is preferably a paediatric tracheostomy tube.

A paediatric 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 side elevation view of the tracheostomy tube; Figure 2 is an enlarged cross-sectional, side elevation view of the machine end of the tube;

Figure 3 is a partly-sectional side elevation view of a modified form of the tube at a preliminary stage of manufacture;

Figure 4 is a side elevation view of the tube of Figure 3 at a later, final stage of manufacture;

Figure 5 is a partly-sectional side elevation view of another modified form of tube at a preliminary stage of manufacture; and

Figure 6 is a side elevation view of the tube of Figure 5 at a later stage of

manufacture.

With reference first to Figures 1 and 2, the tracheostomy tube 1 has a curved shaft 10 of circular section formed from a flexible silicone material having a durometer (Shore A) between 60 and 70. The dimensions of the tube are selected to be suitable for use in paediatric or neonatal patients. The shaft 10 has a patient end 12 adapted to be located within the trachea of the patient. The tube 1 is shown without a sealing cuff but a

conventional sealing cuff could be attached towards its patient end. The machine end 14 of the shaft 10 is adapted, during use, to be located externally of the tracheostomy opening formed in the patient’s neck. The machine end 14 of the shaft 10 is bonded or integrally formed with a hub or connector 15 having a conventional 15mm or 8mm male tapered outer surface 16. The connector 15 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 could be left open to atmosphere when the patient is breathing spontaneously. The tracheostomy tube 1 also includes a radially-extending support flange 20 adapted to lie against the skin surface of the neck on either side of the tracheostomy stoma. The flange 20 is moulded integrally with the shaft 10 about midway along its length or it could be a separate component. The flange 20 has openings (not shown) at opposite ends for attachment to a neck strap (not shown) used to support the tube 1 with the patient’s neck. The flange 20 divides the shaft 10 into a patient end portion 22, adapted to extend through the

tracheostomy and locate in the trachea, and a machine end portion 23, which projects freely outwardly of the tracheostomy away from the patient. This machine end portion 23 provides a flexible connection of the connector 15 with the patient end portion 22 so that die tracheostomy is isolated to some extent from the connector. This enables connection to and disconnection from the connector 15, or repositioning of the connector, to be made with less force being transmitted to the tracheostomy tissue, thereby reducing trauma and discomfort.

It will be appreciated that the tube could be of a different size or shape according to the application.

The silicone material from which the shaft 10 is made has various advantages. It is highly flexible, very compatible with patient tissue and is resistant to the high temperatures used during autoclave heat treatment. The flexible nature of the material, however, means that the machine end portion 23 would be prone to kinking unless steps were taken to prevent this. Present silicone tubes with this configuration therefore usually have their machine end portion reinforced by a helical metal wire. Such an arrangement prevents this portion kinking without substantially reducing its flexibility. The metal wire, however, means that the tube is not compatible with MRI equipment. Even where die reinforcing metal wire is non-ferromagnetic it may still distort the MRI image, especially at higher field strengths.

In the arrangement of the present invention the machine end portion 23 of the shaft 10 is moulded with a wall thickness that is greater than that of the patient end portion 22, typically being about twice the wall thickness of the patient end portion. The outside of the machine end portion 23 is formed with a plurality of discrete regions 17 disposed along and around the machine end portion recessed into its outer surface to increase the flexibility of the machine end portion and reduce the increased stiffness that would otherwise be caused to the thicker wall in this region. More particularly, the discrete regions 17 are typically rectangular recesses with inwardly sloping walls having their length aligned with the circumference of the machine end portion 23. As shown, there are three circumferential rows of recesses 17 arranged end-to-end around the machine end portion. The central row has its recesses staggered midway between the recesses of the adjacent outer two rows. In practice, there would probably be more than three rows of recesses and the machine end portion 23 would be longer than shown. The machine end portion could form a cut-to length connector so that its length could be adjusted to suit different patients. Such an arrangement would require a different mating connector. The pattern of the recesses 17 resembles that of strain relief sleeves commonly used at the ends of cables.

This thickened wall of this arrangement reduces the risk that the machine end portion 23 will kink or buckle when flexed whereas the recesses 17 act as stress-relief formations to increase the flexibility of the machine end portion. In this way the leverage effect caused by the mass of any ventilation tube attached to the machine end connector 15, or any forces applied by such a tube, is reduced.

The entire tube 1 can be made of the same material and can be resistant to autoclave temperatures thereby enabling the tube to be autoclaved after use and reused. This helps reduce the cost of maintaining a patient with a tracheostomy tube and also reduces the cost and environmental damage caused by disposal of clinical waste. The manner in which the machine end portion 23 is reinforced enables the tube 1 to be used safely in MRI

environments, even those with high field strengths. The tube could be modified to make them easier to clean by covering the recesses in the machine end portion by a thin, flexible outer sleeve. Such as sleeve could be formed integrally with the tube in the manner shown in Figures 3 to 6. As shown in Figure 3, such a tube 101 is initially moulded with a machine end portion 123 having an integral, thin, flexible extension sleeve 124 projecting rearwardly, in the machine direction, forming a smooth continuation of the outside of the machine end portion and having a length equal to that of the machine end portion. The next step is simply to turn the sleeve 124 inside out by folding it forwardly about the outside of the machine end portion 123, as shown in Figure 4. A bonding agent or adhesive may be applied to the one or other or both of the outer surface of the machine end portion 123 and to what becomes the inner surface of the sleeve 124 when folded forwardly. This provides a smooth surface to the machine end portion so that it is easier to keep clean.

The extension sleeve 124’ could be used to help retain a connector to the machine end portion 123’ in the manner shown in Figures 5 and 6. In such an arrangement the extension sleeve 124’ is formed with a number of retaining holes 125’ around its

circumference close to where it meets the machine end portion 123’, as shown in Figure 5. A locking ring 126’, forming one part of a two-part connector, is slid forwardly over the extension sleeve 124’ and onto the machine end of the machine end portion 123’. The locking ring 126’ has a number of radially-projecting pins 127’ of a diameter and spacing that enables them to be located in the retaining holes 125’ of the sleeve 124’ when this is folded forwardly in the manner shown in Figure 6. When the extension sleeve 124’ is bonded in position it securely retains the locking ring 126’ on the machine end portion 123’. The outer part 128’ of a two-part connector can then be fitted to the locking ring 126’. This can be achieved by a bayonet twist engagement with the pins 127’ on the locking ring 126’ engaging in slots (not shown) in the outer part 128’ of the connector. Alternatively, the forward, patient end of the outer part 128’ could be welded or bonded to the locking ring 126’

The invention is particularly advantageous in paediatric size tubes, because the small diameter shafts in such tubes makes them more prone to kinking, but is not confined to paediatric sizes. The invention is not confined to tracheostomy tubes but could be used in other tracheal tubes.

Claims

1. A tracheal tube having a shaft (10) with a patient end portion (22) adapted to extend into the body forwardly of a mounting flange (20) and a machine end portion (23, 123, 123’) adapted to project rearwardly of the flange (20) away from the patient, characterised in that the machine end portion (23, 123, 123’) has a wall thickness greater than that of the patient end portion and the machine end portion is provided with a plurality of discrete regions (17, 117, 117’) disposed along and around the machine end portion recessed into the outer surface of the machine end portion (23, 123, 123’) to increase the flexibility of the machine end portion.

2. A tracheal tube according to Claim 1, characterised in that the discrete regions (17,

117, 117’) have a rectangular shape and sloping walls.

3. A tracheal tube according to Claim 1 or 2, characterised in that the discrete regions (17, 117, 117’) are arranged in a plurality of circumferential rows.

4. A tracheal tube according to Claim 3, characterised in that the discrete regions (17,

117, 117’) of adjacent rows are staggered relative to one another.

5. A tracheal tube according to any one of the preceding claims, characterised in that the recesses (17, 117, 117’) in the machine end portion are covered by an outer sleeve (124, 124’).

6. A tracheal tube according to any one of the preceding claims, characterised in that the outer sleeve (124, 124’) is formed integrally with the machine end portion, and that the sleeve (124, 124’) is folded forwardly over the discrete regions (117, 117’) and bonded to the outer surface of the machine end portion (123, 123’).

7. A tracheal tube according to Claim 6, characterised in that the tube includes a locking ring 126’ assembled on the machine end portion 123’ before folding the sleeve 124’ forwardly over the locking ring, that the locking ring 126’ includes radially- projecting pins 127’, that the sleeve 124’ includes retaining holes 125’, and that the pins 127’ locate in the holes 125’ when the sleeve 124’ is folded forwardly over the machine end portion 123’.

8. A tracheal tube according to Claim 7, characterised in that the tube includes a part 128’ of a connector fitted to the locking ring 126’.

9. A method of making a tracheal tube including the steps of forming a tracheal tube (101) having a shaft with a patient end portion adapted to extend into the body forwardly of a mounting flange and a machine end portion (123, 123’) adapted to project rearwardly of the flange away from the patient, the machine end portion (123, 123’) having a wall thickness greater than that of the patient end portion, the machine end portion (123, 123’) being provided with a plurality of discrete regions (117,

117’) disposed along and around the machine end portion recessed into the outer surface of the machine end portion to increase the flexibility of the machine end portion, and an extension sleeve (124, 124’) formed integrally as an extension of the machine end portion (123, 123’); folding the extension sleeve (124, 124’) forwardly over the outside of the machine end portion (123, 123’) to cover the discrete recessed regions (117, 117’) in the machine end portion; and bonding the extension sleeve (124, 124’) in place along the outside of the machine end portion (123, 123’).

10. A tracheal tube formed by a method according to Claim 9.

11. A tracheal tube according to any one of Claims 1 to 8 or Claim 10, characterised in that the entire tube is made of the same material.

12. A tracheal tube according to any one of Claims 1 to 8 or 10 or 11 , characterised in that the shaft is of a silicone material.

13. A tracheal tube according to any one of Claims 1 to 8 or any one of Claims 10 to 12, wherein the tube is a tracheostomy tube.

14. A tracheal tube according to Claim 13 wherein the tracheostomy tube is a paediatric tracheostomy tube.