GB2609294A

GB2609294A - Reinforced tubes

Info

Publication number: GB2609294A
Application number: GB2208296.0A
Authority: GB
Inventors: Beth Morton Laura; Zarembo John; Thomas Jeffrey Andrew
Original assignee: Smiths Medical International Ltd
Current assignee: Smiths Medical International Ltd
Priority date: 2021-06-16
Filing date: 2022-06-07
Publication date: 2023-02-01
Anticipated expiration: 2042-06-07
Also published as: GB2609294B; GB202208296D0; GB202108559D0

Abstract

A medico-surgical tube, in particular a cuffed tracheostomy tube (1, Fig. 1) including a shaft (10, Fig. 1) formed of a flexible plastics material, and a reinforcement member 25 formed as an elongate member of a more rigid plastic formed into a coil extending around the shaft. The reinforcement includes a plurality of struts 27 formed integrally with the coil extending between adjacent turns of the coil to resist displacement of the turns. The wall may be formed of silicone, with the reinforcement comprising multiple loops extending from opposite directions a part way around the shaft to leave a longitudinal gap along which a cuff inflation lumen can extend. The reinforcement may include integral spring arched struts shaped to flex and accommodate limited movement. The loops of one set 26A may be wider than loops of the other set 26B.

Description

REINFORCED TUBES

This invention relates to medico-surgical tubes cf the kind including a shaft and a reinforcement member extending along a part at least of the length of the shaft and overmoulded with a flexible plastics material forming the wall of the shaft, the reinforcement member being provided by at least one elongate member of a more rigid plastics material formed into a coil extending around, or a part way around, the shaft.

Tracheal tubes are used to enable ventilation, respiration, or spontaneous breathing of a patient. 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. 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 tux 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. The anatomy of patients varies considerably according to age and build.

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 soft nature of silicone, 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. Typically, the reinforcement member is a biocompatible metal such as stainless steel, Nitinol, NP35N or the like. However, these metals are not suitable for tubes that need to be used in circumstances where the patient may need scanned in an MM scanner. This is because the high magnetic fields in such scanners may induce heating of the metal component, magnetic attraction cr distortion of the scanner image caused by artifacts, For tubes that need to be MRI compatible the reinforcement member is preferably of a plastics material that is stiffer than the wall material of the shaft. Such a reinforcement coil is preferably pre-moulded from the plastics material and subsequently ovennoulded with the softer wall material. It has been found, however, that the pressure of overmoulding the wall material can distort the reinforcement by laterally cisplacing the turns of the coil towards or away from each other. This can lead to an uneven reinforcement along the length of the tube and a distorted shape of the tube.

It is an object of the present ans en on to provide an alternative reinforced medico-surgical tube.

According to one aspect of the present invention there is provided a medico-surgical tube of the above-specified kind, characerised in that the reinforcement member includes a plurality of struts formed integrally with the coil and extending between adjacent turns of the coil such as to resist displacement of the turns along the length of the shaft.

The struts are preferably shaped to enable them to flex and accommodate limited movement of adjacent turns of the coil. Each strat may be formed into an arch between its ends. The reinforcement member may have ahemate pairs of turns of the coil linked by two struts or by one strut along the length of the coil. The reinforcement member preferably has two pairs of loops extending around the shaft m opposite senses, the loops extending only part way around the shaft to leave a longitudinal pp extending along the shaft, The loops of one set may be wider than the loops of the other set. The reinforcement member may be of a plastics that is stiffer than the flexible plastics forming the wall. The reinforcement member is preferably of a plastics selected from one of poly-ether-ether-keytone, polysulfone, liquid crystal polymer and thermoplastic polyurethane. The flexible plastics forming the wall is preferably of a silicone. The tube may inekde a sealing cuff towards its patient end and an inflation lumen extending through the will of the shaft along the longitudinal gap between the loops. The tube may be a tracheostomy Moe and may include a neck flange spaced between opposite ends of the tube.

According to another aspect of the present invention there is provided a cuffed tracheostomy tube having a shaft with a silicone wall and a reinforcement of a stiff plastics in the form of a coil comprising multiple loops extending around the shaft from opposite directions a part way around the shaft to leave a longitudinal gap, and a cuff inflation lumen extending along the gap from a sealing cuff, the reinforcement including one or two integral spring arched struts linking adjacent loops resiliently to resist displacement of the loops along the length of the shaft.

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 side elevation view of the tracheostomy tube; Figure 2 is perspective phantom drawing of the shaft of the tube; and Figure 3 is a side elevation view of the reinforcement member of the shaft.

With reference first to Figure 1, the tracheostomy tube 1 has a curved shaft 10 of circular section with a forward, distal patient end 11 and a rear, proximal machine end 12. The patient end 11 is adapted to be located within the trachea of the patient and the machine end 11 is adapted to extend through the tracheostomy stoma and to be located externally of the patient. Towards its patient end 11 the shaft 10 supports a conventional sealing cuff 13 of a high-pressure kind made of an elastic material that lies close to the shaft 10 when deflated and is stretched outwardly when inflated. The shaft 10 and cuff 13 are both formed of a soft silicone material and the shaft is reinforced along its length by a reinforcement member or element 25 that will be described in detail later. The machine end 12 of the shaft 10 is terminated by a conventional male tapered connector 14 adapted to make a gas-tight connection in a mating female tapered connector (not shown) at one end of ventilation tubing, or to be left open when the patient is breathing spontaneously. The tube 1 is shown as having a radially extending neck flange 15 spaced about midway along the tube to which a neck tie or strap (not shown) can be fastened in order to secure the tube with the patient's neck. This construction allows for a length of the shaft 10 to project outwardly beyond the flange 15. In alternative tubes the shaft could be shorter, and the connector located directly at the flange so that tube does not project substantially out of the patient. The tube also includes an inflation lumen 16 extending along one side of the shaft 10 and opening towards its patient end 17 under and into the interior of the cuff 13. Adjacent the machine end connector 14 the inflation lumen 16 is joined with one end of a small-bore inflation tube 18 the other end of which is connected to a combined inflation indicator and valve 19. It will be appreciated that the tube could be of a different size, shape, and material according to the application. Where the tube is uncuffed it need not have an inflation lumen.

The construction of the shaft 10 is shown in more detail with reference to Figures 2 and 3 where the shaft is shown straight for simplicity. The shaft I) has a tubular wall 20 of silicone with a generally cylindrical shape and circular section thickened slightly along one side by a region 21. Other flexible plastics materials could be used to form the wall 20. A small diameter bore 23 of circular section, which provides the inflation lumen 16, extends along the length of the thickened region 21. The bore 23 need not have a circular section but could be other shapes, such as oval. The shaft 10 is completed by a reinforcement member or element 25 embedded within the silicone wall 20 such that the wral covers the reinforcement member both externally and internally. The reinforcement member 25 has portions extending around the shaft 10 close to but not crossing the inflation lumen 16 as explained in more detail below.

The reinforcement member 25 takes the form of a single-piece unitary moulding of a plastics material that is relatively stiff compared with the silicone material making up the main part of the wall 20 of the shaft, such as, for example, poly-ether-ether-keytone (PEEK), polysolfone (PSU), a liquid-crystal polymer (LCP) or thermoplastic polyurethane (TPU). The reinforcement member 25 includes an elongate rib 125 of sqiare section along most of its length wound into a coil. The rib 125 winds back and fore aro and and within the wall 20 in a boustrophedon, serpentine, or zig-zag fashion where the portion; extending around the shaft are formed into two pairs of annular turns or loops 26 spaad from one another along the length of the shaft 10 and extending around the shaft in opposite senses. Opposite ends of the loops 26 do not meet but are spaced from one another by a longitudinally extending gap 126 within which the inflation lumen 16 extends. For uncuffed tubes, without any inflation line, there would be no need for the longitudinal gap 126. The loops 26A formed in one direction are wider than the loops 2611 formed in the opposite direction, typically being about three times as wide. The two arms of each of the wider loops 26A are interconnected by one or two spring struts 27 formed integrally of the rib 125. The struts 27 have the same width and thickness as the rib 125 and are formed into a single, curved, sinusoidal arch 127 midway along the length of the struts. The arch 127 of each strut 27 extends laterally of the length of the strut, that is, circumferentially of the reinforcement member 25. The height h of each arch 127 is approximately half the length I of the strut. It can be seen from Figure 3 that the wider loops 26A at opposite ends of the reinforcement member 25 each have just one spring strut 27 and that this is positioned directly opposite the gap 126 between the ends of the loops. The adjacent one of the wider loops 26A at bon ends differ by having two spring structs 27 spaced around the reinforcement member by 900 in opposite senses from the strut in the first one of the loops. The next one of the wider loops 26A has a single strut 27 positioned in alignment with the strut in the first loop, and so on along the length of the reinforcement member 25 in this alternating pattern. The outermost arms of the loops 26A at opposite ends of the reinforcement member 25 have a width about three times the width of the rib 125 along the rest of the reinforcement member so that the free ends of the rib are wider and have a smooth rounded end to prevent cutting through the wall material.

The reinforcement member 25 could be made in various ways. The member could be injection moulded in the finished tubular configuration. Alternatively, it could be made by laser ablation of a solid wall tubular former. In another method a pattern could be cut from a flat sheet of the plastics material and then wrapped around a heated cylindrical mandrel to soften the material to take the desired part-tubu:ar shape The struts 27 provide a resilient interconnection between adjacent turns of the rib 125 that resist separation in a direction along the length of the reinforcement member 25. The shape of the struts 27 ensures that the adjacent;urns of the rib 125 we not entirely prevented from separating or moving closer together but enable small movement so as to ensure that the reinforced shaft 10 can flex without undue force needing to be applied in planes at right angles to its axis.

The inflation lumen 16 is blocked at the patient end 11 of the shaft 10 and a lateral, radial, or side opening 17 into the inflation is skived or otherwise formed from the outer surface of the shaft at a location that lies centrally along tEe length of the sealing cuff 13. The inflation tube 18 is joined to the inflation lumen 16 at the opposite, machine end of the shaft. Assembly operations also include steps of attaching the connector 14 and the flange 15.

The usual way of incorporating the reinforcement member 25 is to form the reinforcement member first, load this in a cavity of an injection moulding tool and overmould the reinforcement member with the silicone or other flexible plastics material forming the wall of the shaft. This overmoulding process requires the wall material to be injected at a relatively high pressure. Without the struts between turns of the member 25 there would be a risk that the turns could be moved laterally, or the plastics waft material could be distorted This could lead to the shape of the finished shaft being distorted and misshaped to an extent that it might be unacceptable for use.

The reinforcement element need not extend along the entire length of the tube. In some tracheostomy tubes it may be preferable for the tube to be reinforced only along that part of its length that extends througll the tracheostomy stoma. A short region al the patient end of the tube could be left unreinforced to provide a soft tip. The rear end of the tube could be left unreinforced to make it easier to insert and retain a tapered coupling. The invention could also have application to reinforced tubes other than tracheal tubes that have an inflatable cuff, such as urethral catheters or vascular dilatation catheters, or tubes that have some other longitudinal member extending within its wail, such as a suction lumen or electrical cable.

The present arrangement can be used to overcome a problem with reinforcement members made of plastics in that, in order to achieve sufficient stiffness to reduce the distortion effects caused during overmoulding, they have to be relatively thick, thereby resulting in either a smaller bore cr a larger external diameter of the tube. The present arrangement can, therefore, enable tubes to be moulded with a polymer reinforcement and be MRI compatible where such tubes previously had to be made with a metal reinforcement that is not MRI compatible.

Claims

CLAIMS1. A medico-surgical tube (1) including a shaft (10) and a reinforcement member (25) extending along a part at least of the length of the shaft and overmouldecl with a flexible plastics material forming the wall (20) of the shaft, the reinforcement member being provided by at least one elongate member of a more rigid plastics material formed into a coil (25) extending around, or a part way around, the shaft, characterised in that the reinforz anent member (25) includes a plurality of struts (27) formed integrally with the coil (25) and extending between adjacent turns of the coil such as to resist displacement cf the turns along the length of the shaft.
2. A tube according to Claim 1, characterised in that the struts (27) are shaped to enable them to flex and accommodate limited movement of adjacent turns of the coil (25).
3. A tube according to Claim 2, characterised in that each strut (27) is formed into an arch (127) between its ends.
4. A tube according to any one of räe preceding claims, characterised in that the reinforcement member (25) has alternate pairs of turns (26) of the coil (25) linked by two struts (27) or by one strut (27) along the length of the coil.
5. A tube according to any one of the preceding claims, characterised in that the reinforcement member (25) has two pairs of loops (26A and 26B) extending around the shaft (10) in opposite senses, and that the loops extend only part way around the shaft to leave a longitudinal gap (126) extending along the shaft.
6. A tube according to Claim 5, characterised in that the loops (26A) of one set are wider than the loops (26B) of the other set,
7. A tube according to any one of the preceding claims, characterised in that the reinforcement member (25) is of a plastics that is stiffer than the flexible plastics forming the wall (20).
8. A tube according to Claim 7, characterised in that the reinforcement member (25) is of a plastics selected from one of poly-ether-ether-keytone, polysulfone, liquid crystal polymer and thermoplastic polyurethane.
9. A tube according to any one of the preceding claims, characterised in that the flexible plastics forming the wall (20) is of a silicone.
10. A tube according to Claim 5 or any claim dependent on Claim 5, characterised in that the tube (1) includes a sealing cuff (13) towards its patient end (11) and an inflation lumen (16) extending through the wall of the shaft along the longitudinal gap (126) between the loops (26).
11. A tube according to any one of the preceding claims, wherein the tube is a tracheostomy tube (1).
12. A tracheostomy tine according to Claim 11, wherein the tube (1) includes a neck flange (15) spaced between opposite ends (11 and 12) of the tube.
13. A cuffed tracheostomy tube (1) having a shaft (10) with a silicone wall (20) and a reinforcement (25) of a stiff plastics in the form of a coil comprising multiple loops (26) extending around the shaft from opposite directions a part way around the shaft to leave a longitudinal gap (126). and a cuff inflation lumen (16) extending along the gap (126) from a sealing cuff (13), wherein the reinforcement (25) includes one or two integral spring arched struts (27) linking adjacent loops (26) resiliently to resist displacement of the loops along the length of the shaft (10).