WO2021219972A1

WO2021219972A1 - Reinforced medico-surgical tubes and their manufacture

Info

Publication number: WO2021219972A1
Application number: PCT/GB2021/000042
Authority: WO
Inventors: John Jay QUACKENBUSH; Yaling Fan; Andrew Robert BEESON
Original assignee: Smiths Medical International Limited
Priority date: 2020-04-27
Filing date: 2021-04-09
Publication date: 2021-11-04
Also published as: GB202006151D0

Abstract

A reinforced, cuffed tracheostomy tube (1) includes a tubular reinforcing structure (11) of a stiff plastics material cut to form several rings (13) spaced along a spine (12). An enlarged rib (45) projects from the rings and receives a small-bore inflation tube (15) extending along the tube. An outer layer (16) of a soft plastics covers the reinforcing structure and inflation line. The inflation line opens at its patient end into a sealing cuff (19) bonded about the tube.

Description

REINFORCED MEDICO-SURGICAL TUBES AND THEIR MANUFACTURE

This invention relates to reinforced medico-surgical tubes of the kind having a reinforcing structure of a relatively stiff plastics.

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 the tube 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 non-metallic helical reinforcement members, such as of stiff plastics can be used. Examples of reinforced tracheal tubes are described in, for example, GB2552250, US5906036, WO2010/089523, EP1078645, WO2015075412, WO08083286, US6148818, US5546936, US5429127, EP0950424, EP2644221, US5628787, US4737153,

US2012/0118294, US4990143, US5181509, US2007083132, US6130406, US6017335 and DE867144. US8783254 describes a tracheostomy tube having a skeletal frame moulded of a stiff plastics and covered by a thin flexible sleeve.

One problem with helically reinforced medico-surgical tubes arises where the tube needs to have a small-bore lumen extending along its length such as to inflate a sealing cuff or for gas sampling, irrigation or suctioning and the like. The presence of the helical reinforcement within the thickness of the wall means that it is not possible to incorporate such a small-bore lumen within the thickness of the wall of the tube without increasing the thickness of the wall. Any increase in wall thickness makes the tube stiffer and, for a given outside diameter, reduces the internal diameter and thereby reduces flow along the bore of the tube. Accordingly, such helically reinforced tubes usually have any longitudinal smallbore lumen provided by a small diameter tube secured in a shallow channel along the outside of the tube. This, however, means that the otherwise smooth external surface of the tube is interrupted along its length by a projecting ridge. This is a particular disadvantage where the tube is used with delicate tissue, such as in paediatric tracheostomy tubes since the ridge can cause damage to tissue. Similar problems exist in other reinforced medico-surgical tubes.

It is an object of the present invention to provide an alternative reinforced medico- surgical tube and a method of making such a tube.

According to one aspect of the present invention there is provided a reinforced medico-surgical tube of the above-specified kind, characterised in that the reinforcing structure has a longitudinal spine, a plurality of ring members extending laterally from the spine, and a channel in which is received a small-diameter elongate member extending along the length of the tube.

The channel may be formed along a rib projecting from the ring members. The elongate member may be a small-bore tube. The tube may include a sealing cuff, the small- bore tube being an inflation tube opening at one end into the sealing cuff. The tube preferably includes a layer of a soft, flexible plastics overlying the reinforcing structure and the elongate member. The layer overlying the reinforcing structure is preferably of silicone. The tube may be a cuffed tracheostomy tube.

According to another aspect of the present invention there is provided a method of making a medico-surgical tube including the steps of extruding a tubular formation of a relatively stiff plastics material and having a main lumen and a smaller channel extending along the length of the tubular formation, cutting the tubular formation with a series of lateral cuts to intersect both lumens and form a series of parallel rings but to leave an elongate spine extending along the formation, threading a small-diameter elongate member through the remaining smaller channel in each ring and subsequently forming a layer of a softer, more flexible plastics material on the cut tubular formation and the small-diameter elongate member.

The elongate member is a preferably a small-bore tube. The method may include the subsequent step of attaching a sealing cuff over the layer of softer material and over an opening from the small-bore tube.

According to a further aspect of the present invention there is provided a medico- surgical tube made by a method according to the above other aspect of the present invention.

The tube may be a cuffed tracheostomy tube.

A reinforced cuffed tracheostomy tube and its 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 a perspective view of the tube;

Figure 2 illustrates schematically extrusion of the tubular stiffening formation; Figure 3 is perspective view of the extruded tubular formation;

Figure 4 is an end view of the tubular formation of Figure 3 ;

Figure 5 is a perspective view of a subsequent stage in the manufacturing process;

Figure 6 is a side elevation of the formation shown in Figure 5;

Figure 7 is a perspective view showing the insertion of the inflation line; and

Figure 8 is a perspective view showing the formation after overmoulding.

With reference first to Figure 1, the tracheostomy tube 1 includes a shaft 10 having a reinforcing structure 11 of a relatively stiff plastics formed with a longitudinal spine 12, a plurality of ring members 13 projecting laterally from the spine and having a channel or small-bore lumen 14 in which is received a small-diameter elongate member in the form of a small-bore inflation tube 15 extending along the length of the tube. The reinforcing structure 11 and inflation tube 15 are covered by an over moulded layer 16 of a relatively soft and flexible plastics material, such as of a soft grade of silicone. The patient end 17 of the shaft 10 is adapted to locate in the trachea; its machine end 18 is adapted to project outwardly through the tracheostomy. Towards the patient end 17, the shaft 10 supports a conventional inflatable sealing cuff 19. The cuff 19 shown is of the high pressure kind made of an elastic material that lies close to the shaft 10 when deflated and is stretched outwardly when inflated. The cuff 19 is attached to the outside of the shaft 10 by two collars 20 and 21 at opposite ends of the cuff. The shaft 10 and cuff 19 are both moulded of a silicone material. The patient end 23 of the inflation tube 15 opens beneath the cuff 19 at a location between the two collars 20 and 21. It will be appreciated that the tube 1 could be of a different sizes, shapes, and materials according to the application.

The machine end 18 of the shaft 10 is bonded into a hub or connector 25 having a conventional 15mm male tapered outer surface 26. The connector 25 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 18 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 30 adapted to lie against the skin surface of the neck on either side of the tracheostomy stoma. The flange 30 could be moulded integrally as one part with the layer 16 of the shaft 10 at its machine end 18 or it could be formed separately and subsequently attached. The flange 30 has openings 31 at opposite ends for attachment to a neck strap (not shown) used to support the tube with the patient’s neck.

The manner in which the shaft 10 of the tube 1 is made will now be described, in greater detail, with reference to Figures 2 to 8.

First, as shown in Figures 2 to 4, an extrusion machine 40 extrudes a tubular formation 41 from a relatively stiff plastics material 42. The formation 41 has a substantially circular section with a main bore 43 and a small bore 44 extending longitudinally in the wall of the formation in an enlarged rib 45 projecting slightly from the outside and inside surface of the formation. This is then cut to the required length for each tube.

In the next step, as shown in Figures 5 and 6, a die cutting tool 50 in the form of a rotating disc with a cutting edge is brought down laterally onto the tubular formation 41 cutting through the rib 45 and down through the major part of the width of the formation but leaving the lower part uncut. Other cutting tools could be used. The cut is repeated along the formation 41 at spaced intervals to leave a longitudinal spine 12 along the formation linking a plurality of ring members 13, each having a short portion of the small bore 44. Each ring 13 could be of the same length or their length could be varied to give different regions of the tube different stiffnesses. The cuts through the tubular formation 40 make it more flexible.

Figure 7 shows the next step in the manufacturing process in which the small-bore inflation tube 15 is threaded through the small bore opening 44 of each ring member 13 along the length of the reinforcing structure 11. In the final step of making the shaft 10, shown in Figure 8, a layer 60 of silicone or other soft plastics material is moulded over the outside of the reinforcing structure 11 and inflation tube 15. This forms a smooth outer surface without any projection from the rib 45 beyond the circular cross-section. Internally, the surface is provided by alternate annular regions 13 of the stiffer material of the reinforcing structure 11 and alternate part-annular regions provided by the softer over-moulded material 60. The over-moulded material may also be integrally moulded to form the flange 30.

The tube 1 is completed by forming an opening through the outside of the shaft 10 to the patient end 23 of the inflation tube 15 and then positioning the inflatable sealing cuff 19 over this opening and bonding its collars 20 and 21 to the outside of the shaft. The flange 30 is then attached to the shaft 10 if this is not integrally moulded with the shaft. The connector 25 is attached to the machine end 18 of the shaft 10 and an inflation line connector 24 is attached to the machine end of the inflation tube 15.

The arrangement of the present invention enables a tube of a relatively soft and flexible plastics material to be reinforced effectively against kinking and crushing without the inflation line or other elongate member protruding along the outer surface. Because the reinforcing structure 11 is of a plastics material, the tube 1 can be safe to use in MRI imaging even at the highest field strengths and without distorting the image.

The invention is not limited to cuffed tubes but could be used with tubes having, for example, a suction or irrigation lumen, or a gas-sampling lumen. In such tubes the smallbore tube would be used for suctioning, irrigation, or gas-sampling respectively. Instead of a small-bore tube, other elongate members could extend along the small bore through the rib on the reinforcing structure instead of or in addition to a small-bore tube such as, for example, an electrical wire or fibre-optic cable. The tube could have more than one small- diameter elongate member extending along respective small-bore channels spaced around the reinforcing structure. The invention is not limited to tracheal tubes but could be used in other medico-surgical tubes, such as urinary catheters or chest drainage tubes. The channel into which the small-bore tube or other elongate member is retained need not have a closed bore of the kind shown in the drawings but could instead be a channel open along its length into which die elongate member is clipped through its longitudinal opening.

Claims

1. A reinforced medico-surgical tube ( 1 ) having a reinforcing structure ( 11 ) of a relatively stiff plastics, characterised in that the reinforcing structure (11) has a longitudinal spine (12), a plurality of ring members (13) extending laterally from the spine, and a channel (44) in which is received a small-diameter elongate member (15) extending along the length of the tube.

2. A tube according to Claim 1, characterised in that the channel (44) is formed along a rib (45) projecting from the ring members (13).

3. A tube according to Claim 1 or 2, characterised in that the elongate member is a small-bore tube (15).

4. A tube according to Claim 3, characterised in that the tube (1) includes a sealing cuff (19), and that the small-bore tube is an inflation tube (15) opening at one end into the sealing cuff (19).

5. A tube according to any one of the preceding claims, characterised in that the tube (1) includes a layer (16) of a soft, flexible plastics overlying the reinforcing structure

(11) and the elongate member (15).

6. A tube according to Claim 5, characterised in that the layer (16) overlying the reinforcing structure (11) is of silicone.

7. A tube according to any one of the preceding claims, wherein the tube is a cuffed tracheostomy tube (1).

8. A method of making a medico-surgical tube (1) including the steps of extruding a tubular formation (11) of a relatively stiff plastics material and having a main lumen (43) and a smaller channel (44) extending along the length of the tubular formation, cutting the tubular formation (11) with a series of lateral cuts to intersect both lumens (43 and 44) and form a series of parallel rings (13) but to leave an elongate spine (12) extending along the formation, threading a small-diameter elongate member (15) through the remaining smaller channel (44) in each ring (13) and subsequently forming a layer (16) of a softer, more flexible plastics material on the cut tubular formation (11) and the small-diameter elongate member (15).

9. A method according to Claim 8, characterised in that the elongate member is a smallbore tube (15).

10. A method according to Claim 9, including the subsequent step of attaching a sealing cuff (19) over the layer (16) of softer material and over an opening from the smallbore tube (15).

11. A medico-surgical tube (1) made by a method according to any one of Claims 8 to

10.

12. A tube according to Claim 11, wherein the tube is a cuffed tracheostomy tube (1).