Medico-surgical tubes

Abstract

A cuffed tracheostomy tube (1) has an expansible sealing cuff (20) secured by opposite end collars (22) and (23) over an inflation opening (18) from the shaft (10) of the tube. The cuff is in the form of a tubular sleeve (20) with a pair of closely spaced annular ribs (33) and (34) around the inner end of each collar (22) and (23), the outer rib (33) preventing the spread of bonding substance (50) from the collars to the inflatable portion (21) of the sleeve. The ribs (33) and (34) on the sleeve lie on opposite sides of respective outwardly-projecting ribs (40) on the shaft so as to locate the sleeve along the shaft. The sleeve also has a series of spaced internal ribs (31) along its inflatable portion (21) to aid even inflation.

Description

[0001] MEDICO-SURGICAL TUBES

[0002] This invention relates to medico-surgical tubes of the kind having a shaft extending between a forward, patient end and a rear, machine end of the tube, the tube including an expansible cuff adapted to contact the wall of a body cavity, the cuff comprising a flexible sleeve joined with the shaft at opposite ends by respective collars attached with the outside of the shaft by a bonding substance and defining between the collars an inflatable portion, the tube including an inflation opening within the inflatable portion.

[0003] The invention is more particularly, but not exclusively, concerned with tracheal tubes with a sealing cuff towards their patient end.

[0004] Airway tubes are often provided with a sealing cuff close to their patient end, which is used to seal the outside of the tube with the trachea so that gas is confined to flow along the bore of the tube. It is important that the seal provided by this cuff be effective but does not damage patient tissue. A poor seal can allow secretions to leak past the cuff and pass down into the lower parts of the respiratory system. It is thought that such secretions entering the lungs may give rise to ventilator-associated pneumonia. The seal provided by the cuff is also important in ensuring that there is no leakage of gas since this could reduce the effectiveness of the ventilation and lead to escape of anaesthesia gases to atmosphere.

[0005] Many different forms of cuff have been proposed in an attempt to improve the seal or interface of a tracheal tube with the trachea. Various different shapes of cuff and surface formations have been proposed, together with modifications in cuff material, coatings or thickness in an attempt to increase the effectiveness of the seal. The most common form of cuff takes the form of a tubular sleeve embracing the shaft of the tube towards its patient end and positioned centrally over the opening of an inflation line extending rearwardly along the shaft. The sleeve has collar regions at opposite ends that are bonded to the outside of the shaft using an adhesive, glue, solvent or other bonding substance to prevent the escape of inflation fluid. It is important that the bonding substance is applied evenly over the region where the collars contact the shaft and does not spread into the inflatable part of the cuff, since this could cause uneven inflation, thereby degrading the seal with patient tissue. It has been proposed in US8281789, US8220462 and US9010333 to form two projecting ribs around the shaft positioned at the inner end of the collars to limit the inward spread of the bonding liquid. This can be effective, but it does rely on the accurate positioning of the cuff relative to the ribs. Also, the ribs may require an additional manufacturing step with some shafts such as those that are extruded. Tubes are provided with expansible cuffs for other purposes than sealing, such as for applying pressure to body tissue.

[0006] It is an object of the present invention to provide an alternative tube and an alternative cuff for a tube.

[0007] According to one aspect of the present invention there is provided a medico-surgical tube of the above-specified kind, characterised in that the sleeve is formed with two inwardly-projecting ribs defining the inner ends of the respective collars such that contact of the ribs with the outer surface of the shaft prevents the spread of bonding substance from the collars to the inflatable portion.

[0008] The shaft preferably includes a projection on its outer surface located at the inner end of a collar to provide a locating feature for one of the ribs on the sleeve. The shaft may include two projections on its outer surface located at the inner end of respective ones of the collars. The sleeve may be formed with one or two pairs of closely-spaced inwardly- projecting ribs to locate on opposite sides of the or each respective projection on the shaft. The sleeve may include a plurality of annular ribs spaced along the inflatable portion of the sleeve. The sleeve and shaft may both be of an elastic material, such as silicone.

[0009] According to another aspect of the present invention there is provided a cuff for a tube according to the above one aspect of the present invention.

[0010] According to a further aspect of the present invention there is provided a method of making a cuffed medico-surgical tube including the steps of providing a shaft and an expansible cuff in the form of a flexible sleeve having a central inflatable portion) and opposite end collars, the inside of the sleeve having two inwardly-projecting ribs located between opposite ends of the inflatable portion and respective end collars, placing the sleeve over the shaft so that the inflatable portion overlies an inflation opening of the tube towards one end of the shaft, and applying a bonding substance between the sleeve and the shaft under each end collar such that the ribs prevent flow of the bonding substance beyond the ribs.

[0011] The outside of the shaft may be provided with two projections spaced on either side of the inflation opening, the sleeve being placed over the shaft prior to applying the bonding substance such that the ribs on the sleeve locate with respective ones of the two projections on the shaft. The bonding substance may be applied by inserting the nose of a bonding applicator under the outer ends of each collar.

[0012] According to a fourth aspect of the present invention there is provided a tube made by a method according to the above further aspect of the present invention.

[0013] A 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:

[0014] Figure 1 is a side elevation view of a tracheostomy tube with an inflated sealing cuff outside a patient;

[0015] Figure 2 is an enlarged, perspective, cut-away view of the patient end of the tube with the sealing cuff in a deflated state;

[0016] Figure 3 is a perspective view of the cuff before fitting on the tube;

[0017] Figure 4 is a further enlargement of a part of Figure 2; and

[0018] Figure 5 illustrates a step in the manufacture of the tube. With reference first to Figure 1, the tube 1 has a moulded shaft 10 with a forward, patient or distal end 11 adapted, during use, for location in the trachea and a rear, machine or proximal end 12 adapted to project outwardly of the tracheostomy stoma. The machine end 12 supports a laterally extending flange 13 that, in use, lies against the skin on either side of the stoma, the flange having openings (not visible) at opposite ends to which the ends of a neck tape (not shown) can be secured to hold the tube in position on the neck. The machine end 12 of the shaft 10 is joined with a 15mm tapered male connector 16, which projects axially outwardly of the flange. An inflation line 17 extends along a channel 17’ in the side of the shaft to an opening 18 at one end towards the patient end 11 of the shaft 10. The inflation line 17 extends through the flange 13 and is terminated at its rear or machine end by a conventional combined inflation indicator and valved connector 19.

[0019] With reference now also to Figures 2 to 4, the shaft 10 carries an inflatable, expansible sealing cuff 20 close to its patient end 11 and positioned centrally over the inflation opening 18 on the outer surface of the shaft. The cuff 20 is of the low-volume, high-pressure kind provided by a tubular elastic sleeve, such as of silicone, that lies close to the outer surface of the shaft 10 when uninflated and is expanded elastically to a sealing state when it is inflated. The cuff or sleeve 20 has a central inflatable portion 21 occupying most of its length that, in use, when inflated, makes a sealing contact with the surface of tissue lining the trachea. At opposite ends, the cuff 20 has respective collars 22 and 23 by which the cuff is attached with the shaft 10. More particularly, the cuff 20 is moulded with a smooth, uninterrupted outer surface 24 along the central inflatable portion 21 linked by respective shallow steps 25 and 26 with the outer surfaces 27 and 28 of the collars 22 and 23. This makes the outer and inner diameters of the collars 22 and 23 slightly less than the corresponding diameters of the central inflatable portion 21. The inner surface 30 of the inflatable portion 21 is smooth apart from four, optional annular ribs 31 equally spaced along the length of this portion. The ribs 31 project from the inner surface 30 by a height equal to approximately one half the thickness of the sleeve 20 so that the major part of the inflatable portion 21 is spaced slightly from the surface of the shaft 10 when deflated. The purpose of the ribs 31 is to ensure an even inflation of the cuff 20 by preventing the inner surface of the inflatable portion 21 sticking to the shaft 10 in the manner described in more detail in US9010333, although the contents of this is not essential for an understanding of the present invention. The ribs 31 are particularly useful where the cuff 20 is of the same material as the shaft, such as silicone.

[0020] Both collars 22 and 23 have a smooth inner surface 32 from their outer ends along their length as far as an inwardly-projecting annular rib 33. The dimensions of the ribs 33 are such that they are flattened slightly by the resilience of the collars 22 and 23 and contact with the outer surface of the shaft 10. In this way the ribs 33 form an effective seal with the shaft 10 at the inner end of the collars 22 and 23 that prevents flow of adhesive, glue, solvent or other bonding substance applied between the collars and the shaft inwardly to the inflatable portion 21. The shaft 10 as illustrated is provided with two external ribs 40 positioned at the desired location of the inner end of each collar 22 and 23. The ribs 40 on the shaft 10 cooperate with the ribs 33 on the sleeve 20 to provide locating features so as to ensure precise positioning of the sleeve along the shaft before the bonding substance is applied. To improve further the positioning of the sleeve 20 along the shaft 10 the inside of the sleeve is moulded with an additional annular rib 34 at each end spaced by a short distance inwardly from the respective outer rib 33. The spacing between the two ribs 33 and 34 is slightly greater than the width of the ribs 40 on the shaft 10 so that the two pairs of ribs on the sleeve can be positioned on either side of the ribs on the shaft.

[0021] The shaft 10 illustrated is moulded with a profiled outer surface towards its patient end adapted to receive the cuff sleeve 20. In particular, the shaft 10 has a cylindrical recess 41 with a depth about half the thickness of the wall of the cuff 20 and a length equal to that of the cuff. The recess 41 is interrupted by the two ribs 40 to divide it into a patient end portion 41’, a central portion 41” and a rear portion 41’”. The length of the patient end portion 41’ and the rear portion 41’” is equal to that of the two collars 22 and 23 so that these locate and are received in these portions with only a reduced thickness of the sleeve 20 projecting above the surface of the shaft 10. The central portion 41” is the same length as the inflatable portion 21 of the cuff 20 with the four ribs 31 on the cuff just contacting or being slightly spaced from the outer surface of the shaft 10. This arrangement helps ensure that the cuff 20 only has a very low profile projecting above the shaft 10 when not inflated, thereby making it easier to insert the tube through patient tissue of the tracheostomy and reducing abrasion with the tissue. It is not essential that the shaft be profiled with the recesses and ribs described above, which might be difficult or more expensive to form in an extruded shaft. Where the shaft is completely smooth on its outer surface the ribs 33 on the inside of the cuff will still serve the purpose of restricting flow of the bonding substance from the collars to the inflatable portion. A cuff for such a shaft would not require the additional locating rib 34. The ribs 31 on the cuff could still be provided if there was a tendency for the inflatable portion of the cuff to stick to the outer surface of the shaft.

[0022] One possible method of manufacturing the tube will now be described with reference to Figure 5 although other methods could be used. Initially, the shaft 10 and cuff 20 are preformed in any conventional manner. The cuff 20 is then slid rearwardly from the patient end 11 of the shaft 10 until it is positioned in the recess 41, or where there is no recess, is located centrally of the inflation opening 18. This may require a lubricant to be applied to the shaft 10 or the inside of the cuff 20. There are other ways of loading the cuff onto the shaft such as by using a mandrel to expand the cuff, or rolling the cuff into a doughnut shape and then rolling this along the shaft to a position where it is unrolled to the desired configuration. The collars 22 and 23 are then bonded to the shaft 10 by applying a bonding substance 50, such as a glue, adhesive or solvent in a liquid or paste form between the collar and the surface of the shaft. This can be done in different ways such as by inserting the nose 51 of a bonding applicator 52 under the collar 22, 23 and dispensing the bonding substance 50 while rotating the shaft 10 and cuff 20. The rib 33 around the inner end of the collar 22 and 23 at each end prevents the bonding substance 50 flowing to the inflatable portion 21 of the cuff 20.

[0023] The cuff need not be of the low-volume, high-pressure kind that lies close to the shaft but could instead be of the high-volume, low pressure kind with a natural floppy shape until it is inflated. The cuff could be inflated with a gas, such as air, or a liquid, such as saline. The cuff could be of the self-inflating kind such as containing a resilient foam that is deflated for insertion and is allowed to expand to form a seal when it is correct position. The tube need not be a tracheostomy tube but could be other forms of tube with an expandable cuff. The cuff need not be a sealing cuff but could, for example, be a dilatation cuff used to expand a region of a blood vessel or other body cavity.

Claims

CLAIMS1. A medico-surgical tube (1) having a shaft (10) extending between a forward, patient end (11) and a rear, machine end (12) of the tube, the tube including an expansible cuff (20) adapted to contact the wall of a body cavity, the cuff comprising a flexible sleeve (20) joined with the shaft at opposite ends by respective collars (22 and 23) attached with the outside of the shaft by a bonding substance (50) and defining between the collars an inflatable portion (18), the tube including an inflation opening (18) within the inflatable portion (21), characterised in that the sleeve (20) is formed with two inwardly-projecting ribs (33) defining the inner ends of the respective collars (22 and 23) such that contact of the ribs (33) with the outer surface of the shaft (10) prevents the spread of bonding substance (50) from the collars (22 and 23) to the inflatable portion (21).

2. A tube according to Claim 1, characterised in that the shaft (10) includes a projection (40) on its outer surface located at the inner end of a collar (22, 23) to provide a locating feature for one of the ribs (33) on the sleeve (20).

3. A tube according to Claim 2, characterised in that the shaft (10) includes two projections (40) on its outer surface located at the inner end of respective ones of the collars (22 and 23).

4. A tube according to Claim 2 or 3, characterised in that the sleeve (20) is formed with one or two pairs of closely-spaced, inwardly-projecting ribs (33 and 34) to locate on opposite sides of the or each respective projection (40) on the shaft (10).

5. A tube according to any one of the preceding claims, characterised in that the sleeve (20) includes a plurality of annular ribs (31) spaced along the inflatable portion (21) of the sleeve (20).

6. A tube according to any one of the preceding claims, characterised in that the sleeve (20) is of an elastic material, such as silicone.

7. A tube according to Claim 6, characterised in that both the sleeve (20) and the shaft (10) are of a silicone material.

8. A cuff (20) for a tube (1) according to any one of the preceding claims.

9. A method of making a cuffed medico-surgical tube (1) including the steps of providing a shaft (10) and an expansible cuff in the form of a flexible sleeve (20) having a central inflatable portion (21) and opposite end collars (22 and 23), the inside of the sleeve (20) having two inwardly-projecting ribs (33) located between opposite ends of the inflatable portion (21) and respective end collars (22 and 23), placing the sleeve (20) over the shaft (10) so that the inflatable portion (21) overlies an inflation opening (18) of the tube towards one end of the shaft, and applying a bonding substance (50) between the sleeve (20) and the shaft (10) under each end collar (22 and 23) such that the ribs (33) prevent flow of the bonding substance (50) beyond the ribs.

10. A method according to Claim 9, characterised in that the outside of the shaft (10) is provided with two projections (40) spaced on either side of the inflation opening (18), and that the sleeve (20) is placed over the shaft (10) prior to applying the bonding substance (50) such that the ribs (33) on the sleeve (20) locate with respective ones of the two projections (40) on the shaft (10).

11. A method according to Claim 10, characterised in that the bonding substance (50) is applied by inserting the nose (51) of a bonding applicator (52) under the outer ends of each collar (22 and 23).

12. A tube (1) made by a method according to any one of Claims 9 to 11.

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