Cuffed medico-surgical tubes

Abstract

A tracheostomy tube has a shaft (1) and an elastic inflatable sealing cuff (10) attached at its opposite ends to the outside of the shaft to provide an inflatable portion (10') of the cuff between its opposite ends. The outer surface of the shaft (1) is formed in the region of the shaft underlying the inflatable portion of the cuff with a series of annular protruding ribs (30) arranged to limit the area of the shaft (1) contacted by the inflatable portion (10') of the cuff (10) before inflation. The ribs (30) are formed with at least two gaps (33 and 34) to enable inflation fluid to flow between the ribs (30) when the cuff is deflated into contact with the ribs (30).

Description

[0001] CUFFED MEDICO-SURGICAL TUBES

[0002] This invention relates to cuffed medico-surgical tubes of the kind having a shaft and a sealing cuff mounted on the shaft.

[0003] More particularly, but not exclusively, the tube could be a tracheal tube, such as a tracheostomy tube.

[0004] Tracheal tubes are used to supply ventilation and anaesthetic gases tb a patient, such as during surgery. The tracheal tube may be inserted via the mouth or nose, in the case of an endotracheal tube, or may be inserted via a surgically-made tracheostomy opening in the neck, in the case of a tracheostomy tube. Most, but not all, tracheal tubes have some form of a seal on their outside which forms a seal between the outside of the tube and the inside of the trachea so that gas flow is confined to the bore of the tube and cannot flow around the outside of the tube, between the tube and the trachea.

[0005] The most common form of seal is provided by an inflatable cuff that is inflated and deflated via a small bore lumen extending along the tube and connected towards its rear end to an inflation line terminated by an inflation indicator, valve and connector. These inflatable cuffs may be of the high-volume / low-pressure kind where the cuff is formed of a flexible plastics material moulded with a natural cylindrical or doughnut shape that is inflated without stretching, to contact the wall of the trachea, by relatively low-pressure gas supplied via the inflation line. Alternatively, the cuff may be of the low-volume / high-pressure kind where the cuff is of an elastic material that lies close to the tube shaft when uninflated but is inflated and stretched to a larger diameter by relatively high-pressure gas supplied via the inflation line. These cuffs can also be inflated with a liquid. There is a problem with cuffed tubes, which particularly applies to tubes where the shaft and cuff are of silicone and the cuff is of the low-volume / high-pressure kind, which lies close to the shaft before inflation. With such cuffs there is a tendency for the inside of the cuff to stick to the outside of the tube shaft during assembly, storage, and sterilisation. The result of this is that, when the cuff is inflated, it may inflate to a deformed or asymmetric shape. This can lead to a poor seal with the trachea and uneven sealing pressure with the trachea around the tube. This can cause leakage around the cuff or damage to the tracheal lining. To reduce the risk of sticking, the current practice is to apply a liquid coating of a non-stick substance to the inner surface of the cuff. If, however, the coating is carried out before the cuff is assembled on the tube shaft it can cause a poor joint between the cuff and the tube. Instead, the coating is usually applied to the cuff after one end of the cuff has been bonded to the tube shaft. This can be a difficult procedure to carry out without inadvertently coating the collar region of the cuff that is to be bonded to the shaft. Alternatively, a lubricant could be applied after attaching the cuff to the shaft by injecting it inside the cuff along the inflation line. This technique presents difficulties in achieving an even spread of lubricant over the inside of the cuff and it is also difficult to remove excess lubricant. It has also been proposed, in US9010333, to mould the cuff with a series of internal annular ribs along the inflatable portion of the cuff to reduce adhesion between the cuff and the shaft. Although this arrangement can help, it is thought that the ribs could weaken the cuff because the ribs may set up stress concentrations in the cuff material, and increased hysteresis, causing tension set and leading to an increased risk of premature bursting at higher pressures. It would be possible to reduce the risk of damage to the cuff caused by this if the wall thickness of the cuff were increased but this would require higher pressures to inflate the cuff. This, in turn, would lead to increased pressure within the pilot balloon and inflation line, and an increased risk that these, or their joints, would rupture.

[0006] It is an object of the present invention to provide an alternative cuffed tube.

[0007] According to one aspect of the present invention there is provided a medico-surgical tube having a shaft and an inflatable sealing cuff attached at its opposite ends to the outside of the shaft to provide an inflatable portion of the cuff between its opposite ends, the outer surface of the shaft being formed at least in the region of the shaft underlying the inflatable portion of the cuff with protrusions arranged to limit the area of the shaft contacted by the inflatable portion of the cuff before inflation.

[0008] The region of the shaft may be provided by a recess with an external diameter less than that of a major part of the length of the shaft. The height of the protrusions is preferably not greater than the depth of the recess. The protrusions may be in the form of a series of annular ribs spaced along said region, the ribs extending at least part way around the circumference of the shaft. Where the protrusions are annular ribs it is preferable that they do not extend completely around the circumference of the shaft but instead leave a gap to allow flow of the inflation fluid in or out of the cuff when the cuff is deflated or partly deflated. The shaft and cuff are preferably of a silicone material. The tube may be a tracheal tube, such as a tracheostomy tube.

[0009] According to another aspect of the present invention there is provided a tracheostomy tube having a shaft and an elastic inflatable sealing cuff attached at its opposite ends to the outside of the shaft to provide an inflatable portion of the cuff between its opposite ends, the outer surface of the shaft being formed at least in the region of the shaft underlying the inflatable portion of the cuff with a series of annular protruding ribs arranged to limit the area of the shaft contacted by the inflatable portion of the cuff before inflation, the ribs being formed with at least one gap to enable inflation fluid to flow between the ribs when the cuff is deflated into contact with the ribs.

[0010] A tracheostomy tube according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0011] Figure 1 is a side elevation view of the tube;

[0012] Figure 2 is a perspective view of the tube from the side on the inside of its curvature;

[0013] Figure 3 is a perspective view of the tube from the side on the outside of its curvature;

[0014] Figure 4 is an enlarged side elevation view of the patient end of the tube; and

[0015] Figure 5 is a further enlargement of a part of the view in Figure 4. The tracheostomy tube includes a tubular shaft 1 having a bore 2 extending along its length. The shaft 1 is formed with a relatively straight patient end portion 3 and a curved machine end portion 4 arranged so that the patient and machine ends 5 and 6 are angled at about 100° to one another. The shaft 1 is extruded or moulded from a plastics material such as silicone. At its machine end 6 the tube has a flange 7 (omitted from Figures 2 to 5), to which a neck strap (not shown) is attached, and a standard 15mm male coupling 8. The tracheostomy tube could be of different shapes and materials.

[0016] Towards its patient end 5 the tube has a sealing cuff indicated generally by the numeral 10. The cuff 10 (shown in Figure 1 in its inflated, sealing state) has a natural, uninflated cylindrical shape and circular section along its entire length. The cuff 10 is preferably of a silicone or other elastic material that lies close to the outside of the shaft 1 when uninflated. The cuff 10 is attached to the outside of the shaft 1 at opposite ends to overlie an opening 11 close to the patient end of an inflation line 12 provided by a small diameter tube bonded into a channel 13 formed along the outer surface of the shaft. The opposite end of the inflation line 12 extends through the flange 7 and then extends freely to a conventional combined valved connector and inflation indicator or pilot balloon 14 by which inflation fluid (gas or liquid) is supplied to and from the sealing cuff 10. Alternative inflation lines could be used such as including a lumen extruded within the thickness of the wall of the shaft.

[0017] At opposite ends of the region “A”, where the cuff 10 extends along the shaft 1, the external diameter of the shaft is reduced slightly forming two shallow, cylindrical attachment bands 21 and 22. The cuff 10 is secured with the shaft 1 by a bond between collars 23 and 24 at opposite ends of the cuff and respective ones of the bands 21 and 22. The inner end of each band 21 and 22 is bounded by respective projecting rings 25 and 26 having a height equal to the external diameter of the main part of the shaft 1. The rings 25 and 26 act as dams to prevent the adhesive or solvent used to bond the collars 23 and 24 to the shaft 1 flowing inwardly into a central portion “B” of the region “A” in the manner described in US8220462 and US8281789 but the contents of these documents is not necessary for an understanding of the present invention. The central portion “B” forms a shallow recess 9 with an external diameter slightly less than the diameter of the major part of the length of the shaft 1. The cuff 10 is unattached to the shaft 1 along this recess 9 and hence is inflatable along this region. The external surface of this recess 9 is interrupted by protrusions arranged to limit the area of the shaft 1 contacted by the inflatable portion 10’ of the cuff 10 before inflation. In the example shown in the drawings the protrusions are provided by a series of eight outwardly-projecting ribs 30 moulded integrally with the shaft 1 to extend circumferentially around its outside and equally spaced along the recess 9 between the two dam rings 25 and 26. The ribs 30 are shown most clearly in Figure 5 where it can be seen that they have a main, central curved section 31 joining with the outer surface of the shaft by a radiused edge 32 on opposite sides. The height of the ribs 30 may be equal to that of the dam rings 25 and 26, that is, level with the outer surface of the main part of the shaft 1 but their height is preferably less than this.

[0018] Preferably the ribs 30 do not extend completely around the circumference of the shaft 1 but instead are interrupted to leave at least one gap to allow the inflation fluid to flow in or out of the cuff 10 when the cuff is deflated or partly deflated. In the arrangement shown, each rib 30 is interrupted by two gaps 33 and 34 on opposite sides of the shaft 1 and lying along the plane of curvature of the shaft. The gaps 33 and 34 of each rib 30 align with one another so that there are two fluid paths along opposite sides of the shaft 1 by which inflation fluid can flow in or out of the cuff 10. The six ribs 30 closer to the machine end of the tube are also interrupted midway between the two rows of gaps 33 and 34 by the channel 13 and the inflation line 12, which extend to a location approximately midway along the inflatable region “B”. The opening 11 from the inflation line 12 lies on one side of the line and close to its patient end. The opening 11 opens into a shallow indentation 121 formed midway along the inflatable region “B” and extending across two of the central ribs 30 to promote flow of the inflation fluid between the cuff 10 and the outside of the shaft 1.

[0019] The outer surface of the shaft could have a different number of protrusions formed in the region of the shaft underlying the inflatable portion of the cuff. These could be of different shapes, configurations, and sizes arranged to limit the area of the shaft contacted by the inflatable portion of the cuff before inflation.

[0020] The invention is not confined to tracheostomy tubes but could be used in other cuffed medico-surgical tubes.

Claims

CLAIMS1. A medico-surgical tube having a shaft (1) and an inflatable sealing cuff (10) attached at its opposite ends to the outside of the shaft to provide an inflatable portion (10’) of the cuff between its opposite ends, characterised in that the outer surface of the shaft (1) is formed at least in a region (A) of the shaft underlying the inflatable portion (10’) of the cuff (10) with protrusions (30) arranged to limit the area of the shaft (1) contacted by the inflatable portion (10’) of the cuff before inflation.

2. A medico-surgical tube according to Claim 1 , characterised in that the region (A) of the shaft (1) is provided by a recess (9) with an external diameter less than that of a major part of the length of the shaft (1).

3. A medico-surgical tube according to Claim 2, characterised in that the height of the protrusions (30) is not greater than the depth of the recess (9).

4. A medico-surgical tube according to any one of the preceding claims, characterised in that the protrusions are in the form of a series of annular ribs (30) spaced along region (9), and that the ribs (30) extend at least part way around the circumference of the shaft (1).

5. A medico-surgical tube according to Claim 4, characterised in that the ribs (30) do not extend completely around the circumference of the shaft (1) but instead leave a gap (33, 34) to allow flow of the inflation fluid in or out of the cuff (1) when the cuff is deflated or partly deflated.

6. A medico-surgical tube according to Claim 5, characterised in that the tube has two gaps (33 and 34) extending along opposite sides of the shaft (1).

7. A medico-surgical tube according to any one of the preceding claims, characterised in that the tube includes an inflation line (12) extending along a part at least of thelength of the shaft (1), and that the inflation line has an opening (11) located in and indentation (121) in the region (A).

8. A medico-surgical tube according to any one of the preceding claims, characterised in that opposite ends of the cuff (10) are attached with the shaft (l)in respective bands (21 and 22) around the shaft (1), and that the projecting rings (25 and 26) are located between respective bands (21 and 22) and the region (A) underlying the inflatable portion (10’) of the cuff (10).

9. A medico-surgical tube according to any one of the preceding claims, characterised in that the shaft (1) and cuff (10) are of a silicone material.

10. A medico-surgical tube according to any one of the preceding claims, characterised in that the tube is a tracheal tube, such as a tracheostomy tube.

11. A tracheostomy tube having a shaft (1) and an elastic inflatable sealing cuff (10) attached at its opposite ends to the outside of the shaft to provide an inflatable portion (10’) of the cuff between its opposite ends, characterised in that the outer surface of the shaft (1) is formed at least in the region of the shaft underlying the inflatable portion of the cuff with a series of annular protruding ribs (30) arranged to limit the area of the shaft (1) contacted by the inflatable portion (10’) of the cuff (10) before inflation, and that the ribs (30) are formed with at least one gap (33, 34) to enable inflation fluid to flow between the ribs (30) when the cuff (10) is deflated into contact with the ribs (30).

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