WO2020025912A1

WO2020025912A1 - Tracheal tube and method of making said tube

Info

Publication number: WO2020025912A1
Application number: PCT/GB2019/000098
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: GB201812444D0

Abstract

A silicone paediatric tracheostomy tube (1, 101) has a machine end portion (23, 123, 123') corrugated on its outer and inner surfaces to reinforce this portion and maintain flexibility. The corrugations are covered by a thin extension sleeve (30, 130, 130') to provide a smooth outer surface. The sleeve (130) may be formed integrally with the machine end portion (123, 123') and 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 lead to distortion of the 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 tracheal tube and method of making a 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 is corrugated at least on its outer surface along at least a major part of its length and has an outer cover sleeve of a flexible material disposed along the corrugated part to provide a smooth, uncorrugated outer surface of the machine end portion. The machine end portion is preferably corrugated on both its outer and inner surfaces. The cover sleeve may be moulded integrally with the machine end portion as an extension sleeve extending rearwardly of the machine end portion and may subsequently be folded forwardly about the corrugated machine end portion. The tube may include a locking ring on the machine end portion, the locking ring including radially-projecting pins, the sleeve including retaining holes, and 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 moulding a machine end portion of a tracheal tube having enhanced flexibility from corrugations at least on the outer surface of the machine end portion, moulding integrally with the machine end portion an extension sleeve extending rearwardly of the machine end portion and subsequently folding the extension sleeve forwardly about the corrugated machine end portion to provide a smooth

uncorrugated outer surface over the corrugations.

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 may be of a silicone material. The tube is preferably a tracheostomy tube, such as a paediatric 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 partly sectional side elevation view of a preliminary stage of

manufacture of a tube made by a modified method; Figure 3 is a side elevation view of the modified tube of Figure 2 at a final stage of manufacture;

Figure 4 is a partly-sectional side elevation view of another modified tube at a preliminary stage of manufacture; and

Figure 5 is a side elevation view of the modified tube of Figure 4 at a later stage of manufacture.

With reference first to Figure 1 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, dining 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 the 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, that the tube could be made of other materials and that different couplings could be used.

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 the 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 series of multiple annular corrugations 24 extending circumferentially around the machine end portion such that both the outer and inner surface of this portion is corrugated. The corrugations 24 form recesses between them and give the machine end portion 23 enhanced flexibility but are relatively stiff radially, thereby resisting kinking or buckling. The flexible nature of the machine end portion 23 reduces the leverage effect caused by the mass of any breathing tube attached to the machine end connector 15, or any forces applied by such a tube. The corrugations 24 are shown as having a V-shape but they could be formed by a rounded, undulating profile. Alternatively, the machine end portion 23 could be corrugated externally but have a smooth, uncorrugated bore.

The tube 1 is completed by a separate outer cover sleeve 30 of a thin, flexible material disposed along the corrugated part of the machine end portion 23 to provide a smooth, uncorrugated outer surface of the machine end portion. The sleeve 30 is separately moulded or extruded and is slipped onto the machine end portion 23 using a bonding solution or adhesive to secure it with the outside of the machine end portion. This makes it easier to keep the outside of the machine end of the tube clean and prevents material collecting between the recesses formed between the corrugations 24 on the outside of the tube, which could provide sites for bacterial infection. The flexible nature of the sleeve 30 enables it to flex freely with the machine end portion 23.

The entire tube 1 including the cover sleeve 30 can be made of the same material and can be resistant to autoclave temperatures. This enables the tube to be autoclaved after use and then reused. In this way the cost of maintaining a patient with a tracheostomy tube can be reduced and the cost and environmental damage caused by disposal of clinical waste can also be reduced. The manner in which the machine end portion 23 is reinforced by corrugations enables the tube 1 to be used safely in MRI environments, even those with high field strengths.

Instead of using a separate sleeve 30 to cover the corrugations 124 a sleeve 130 could be formed integrally with the tube 101 in the manner shown in Figures 2 and 3. As shown in Figure 2, such a tube 101 is initially moulded with a machine end portion 123 having an integral, thin, flexible extension sleeve 130 projecting rearwardly, in the machine direction, forming a 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 130 inside out by folding it forwardly about the outside of the machine end portion 123, as shown in Figure 3. 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 130 when folded forwardly, as shown in Figure 3. This provides a smooth, uncorrugated outer surface to the machine end portion so that it is easier to clean. Instead of bonding the sleeve over the corrugations it could be held in place mechanically such as elastically or by heat shrinking.

An extension sleeve 130’ could be used to help retain a connector to the machine end portion 123’ in the manner shown in Figures 4 and 5. In such an arrangement the extension sleeve 130’ 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 4. A locking ring 126’, forming one part of a two-part connector, is slid forwardly over the extension sleeve 130’ 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 locate in and project slightly through the retaining holes 125’ of the sleeve 130’ when this is folded forwardly in the manner shown in Figure 5. When the extension sleeve 130’ 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.

Claims

1. A tracheal tube (1, 101) 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’) is corrugated at least on its outer surface along at least a major part of its length and has an outer cover sleeve (30, 130, 130’) of a flexible material disposed along the corrugated part to provide a smooth, uncorrugated outer surface of the machine end portion.

2. A tracheal tube according to Claim 1 , characterised in that the machine end portion (23, 123, 123’) is corrugated on both its outer and inner surfaces.

3. A tracheal tube according to Claim 1 or 2, characterised in that the cover sleeve (130, 130’) is moulded integrally with the machine end portion (123, 123’) as an extension sleeve extending rearwardly of the machine end portion and is subsequently folded forwardly about the corrugated machine end portion.

4. A tracheal tube according to Claim 3, characterised in that the tube includes a locking ring (126’) on the machine end portion (123’), that the locking ring (126’) includes radially-projecting pins (127’), that the sleeve (130’) includes retaining holes (125’), and that the pins (127’) locate in the holes (125’) when the sleeve (130’) is folded forwardly over the machine end portion (123’).

5. A tracheal tube according to Claim 4, characterised in that the tube includes a part (128’) of a connector fitted to the locking ring (126’).

6. A method of making a tracheal tube including the steps of moulding a machine end portion (123, 123’) of a tracheal tube having enhanced flexibility from corrugations at least on the outer surface of the machine end portion, moulding integrally with the machine end portion an extension sleeve (130, 130’) extending rearwardly of the machine end portion (123, 123’) and subsequently folding the extension sleeve (130, 130’) forwardly about the corrugated machine end portion to provide a smooth uncorrugated outer surface over the corrugations.

7. A tracheal tube made by a method according to Claim 6.

8. A tracheal tube according to any one of Claims 1 to 5 or Claim 7, characterised in that the entire tube is made of the same material.

9. A tracheal tube according to any one of Claims 1 to 5 or 7 or 8, characterised in that the shaft is of a silicone material.

10. A tracheal tube according to any one of Claims 1 to 5 or any one of Claims 7 to 9, wherein the tube is a tracheostomy tube.

11. A tracheal tube according to any one of Claims 1 to 5 or any one of Claims 7 to 10, wherein the tube is a paediatric tube.