WO2015092343A1

WO2015092343A1 - Cuffed tubes

Info

Publication number: WO2015092343A1
Application number: PCT/GB2014/000468
Authority: WO
Inventors: Stephen James Field; Eric Pagan; Jonathan McNeill FLINT
Original assignee: Smiths Medical International Limited
Priority date: 2013-12-16
Filing date: 2014-11-14
Publication date: 2015-06-25
Also published as: GB201322200D0; EP3082921A1

Abstract

A tracheal tube has a sealing cuff (10, 120, 400, 510) towards its patient end of a visco- elastic foam material covered by a layer (101, 101 ', 402, 502) of an impervious material. The cuff (10) may extend along its length in contact with the outside of the shaft (1, 1', 1") or the cuff (120) may have a wall of visco-elastic foam material defining a space (204) between the outside of the shaft (1 ') and the inside of the cuff when this is inflated.

Description

CUFFED TUBES

This invention relates to medico-surgical tubes of the kind including a shaft having a patient end adapted for insertion within a body space and a sealing cuff mounted with the outside of the shaft towards its patient end adapted to provide a seal between the outside of the shaft and the inside of the body space.

The invention is more particularly, but not exclusively, concerned with cuffed tracheal tubes.

Airway devices are often provided with a sealing cuff close to their patient end, which is used to seal the outside of a 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 and that it 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 (VAP). 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. One possible cause of leakage around the cuff is the presence of longitudinal creases in the cuff material, which can provide flow paths between the cuff and patient tissue. Another problem with sealing cuffs is ensuring that an adequate seal is maintained without exerting excessive pressure on the lining of the trachea.

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. In place of conventional inflated cuffs it has been proposed to use multiple discs or flanges to provide a seal, as described in US3659611, US5322062, US5429127 and US5537729. US8584677 describes a seal provided by a brush-like material formed by closely-packed short fibres. There are also other medico-surgical devices where there is a need to enhance the interface between the device and body tissue. Tubes are also available with a foam cuff, such as the Bivona Aire- Cuf tube (Bivona and Aire-Cuf are trade marks of Smiths Medical). A tube with a foam cuff is described, for example, in US3640282.

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

According to one aspect of the present invention there is provided a medico-surgical tube of the above-specified kind, characterised in that the sealing cuff includes a part at least of a visco-elastic foam material.

The foam material may be of visco-elastic polyols. The cuff may extend in contact with the outer wall of the shaft along the length of the cuff. Alternatively, the cuff could include a wall of visco-elastic foam material, the wall defining a space between the outside of the shaft and the inside of the wall when the cuff is in an expanded state. The cuff may include a layer of an impervious material, which may extend over an external surface of the cuff. Alternatively, the layer of impervious material may be on an inside surface of the cuff, the layer of impervious material being bonded with the outside of the shaft. The shaft preferably includes a lumen extending along the shaft and opening into the cuff by which gas can flow to or from the cuff to allow it to inflate and deflate. Alternatively, the tube could include a vent passage opening into the cuff to allow air to flow into and out of the cuff as it expands and contracts. The cuff of foam material may be formed integrally with a foam patient end tip of the shaft. The cuff of foam material may be formed integrally with a foam surface on a patient-facing surface of a flange at the machine end of the tube. The foam material may be covered by an outer layer of impervious material.

According to another aspect of the present invention there is provided a medico- surgical tube including a shaft having a patient end adapted for insertion within a body space and a sealing cuff attached with the outside of the shaft towards its patient end adapted to provide a seal between the outside of the shaft and the inside of the body space,

characterised in that the sealing cuff includes a wall a part at least of which is formed of a foam material, and that the wall defines a space between the outside of the shaft and the inside of the wall when the cuff is in an expanded state. The wall of the cuff is preferably between 0.5mm and 2mm thick. The foam may be gas-permeable, the cuff including a layer of impermeable material. The layer of impermeable material may be on the inner surface of the cuff, the layer of impermeable material being bonded with the outside of the shaft. The tube may include a vent passage opening into the cuff to allow air to flow into and out of the cuff as it expands and contracts. The cuff may be arranged such that it compresses during insertion into and removal from the trachea.

The tube may be a tracheal tube, such as a tracheostomy tube.

Different forms of tracheostomy tubes 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 first form of tube;

Figure 2 is an enlarged cross-sectional view through a part of the cuff of the tube of Figure 1 ;

Figure 3 is an enlarged cross-sectional view showing a part of a cuff of an alternative form of tube;

Figure 4 is a perspective view showing the tube of Figure 3 with the sealing cuff separated;

Figure 5 is an enlarged cross-sectional view showing a part of a cuff of another alternative form of tube;

Figure 6 is a perspective view of a fourth form of tube at a preliminary stage of manufacture; and

Figure 7 is a perspective view of a fifth form of tube. With reference first to Figures 1 and 2, the tracheostomy tube includes a tubular shaft 1 having a bore 2 extending along its length. The tube is formed with a relatively straight patient end portion 3 and a relatively straight machine end portion 4 linked by a curved intermediate portion 5 so that the patient and machine ends 6 and 7 are angled at about 100° to one another. Other conventional tube configurations could be used. The shaft 1 is extruded or moulded from a plastics material such as PVC or silicone. Towards its patient end 6 the tube has sealing means provided by a sealing cuff 10 embracing the shaft 1. The cuff 10 is attached to the shaft 1 and its inner surface lies in contact with the shaft along its length. The cuff extends over an opening 11 on the outer surface of the shaft 1 into an inflation lumen 12 extending along the shaft within its wall thickness. The inflation lumen 12 is connected towards the rear end of the tube with a small-bore inflation line 13 that is terminated by a combined inflation indicator, valve and connector 14.

At its machine end 7 the tube has a flange 20, to which a neck strap (not shown) is attached, and a standard 15mm female coupling 21.

The tube differs from conventional tubes in that the sealing cuff 10 is made substantially of a visco-elastic foam material 100, such as visco-elastic polyols. This material 10 has the property of only slowly recovering its natural shape after removal of an external force. It may also have the characteristic of being more readily deformed by external force at elevated temperature, such as at body temperature. The foam material 100 is a solid mass that fills the entire volume of the cuff 10 extending from the outside wall of the shaft 1. The foam material 100 is naturally permeable to gas so is covered by an external layer 101 provided by a thin coating of a flexible, impermeable plastics such as urethane. Before insertion in a patient, the cuff 10 is deflated or sucked down by applying a negative pressure to the connector 14 (such as using a syringe) so that the external dimensions of the cuff are reduced sufficiently to allow insertion through the tracheostomy opening. When the tube has been correctly positioned in the patient, the connector 14 is opened to allow air to flow along the inflation line 13 and lumen 12 into the cuff 10. The natural resilience of the cuff material 100 causes it to expand outwardly and fill with air until it contacts the inside of the trachea. As the outside of the cuff 10 contacts the tracheal wall it is warmed and the contact forces cause the visco-elastic foam material 100 to deform to accommodate the surface profile of the trachea. This ensures a very close, intimate contact with surface formations of the tracheal wall. Consequently, it ensures a very effective gas seal and an effective seal against the passage of secretions. The cuff 10 naturally accommodates any changes caused by relative movement between the tube and patient, and changes in airway pressure during ventilation cycling. This ensures that an effective seal is maintained during use and without the need to monitor and adjust cuff pressure externally as is the case with conventional pressure-inflated cuffs.

When it is necessary to remove the tube, a syringe or the like is connected to the connector 14 and a negative pressure is applied to suck down the cuff 10 to a smaller diameter.

Instead of making the cuff of a solid mass of foam filling the entire volume of the cuff from the outside wall of the shaft it would, instead, be possible to have a cuff with just a relatively thin wall of a foam enclosing a hollow air space 204 around the shaft as shown in Figures 3 and 4. In this arrangement the cuff 200 has a wall thickness in the range 0.5mm - 2mm, which is considerably thicker than conventional inflatable cuffs. Opposite ends 201 and 202 of the cuff are attached to the tube shaft 1 ' in a recessed region 203 having a depth substantially equal to the thickness of the cuff wall. This ensures that the outer surface of the cuff 200 at its ends lies level with the external surface of the shaft 1 '. Where the cuff or the tube wall is thin, however, it may be preferred not to form a recess in the tube wall. The foam material of the cuff 200 is preferably of a visco-elastic material and it may be preferable to provide the layer 101 ' of impermeable plastics on the inner rather than the outer surface of the cuff so as to achieve a better bond with the shaft 1 '. This could be achieved by forming an impermeable layer on the outside of the cuff and then inverting it so that the impermeable layer lies on the inner surface. It might be possible, however, for the impervious layer to extend along the external surface of the cuff instead. It is not essential that this cuff be formed of a visco-elastic material since other foam materials could be used. Where a foam that is naturally impermeable is used it would not be necessary to have a separate impermeable layer. The cuff 200 shown in Figures 3 and 4 is positioned over the open end 11 Of an inflation lumen 12' so that it can be sucked down against the shaft Γ for insertion and removal. Gas can also be supplied via the lumen 12' to aid inflation of the cuff 200 after it has been positioned in the patient. Alternatively, the resilience of the cuff 200 may itself be sufficient to allow the cuff to be self-inflating. It will be appreciated that the reduced bulk of the cuff 200 compared with the cuff 10 described with reference to Figures 1 and 2 means that it will not be capable of producing as much expansion force.

It may not be essential for the tube to have an inflation lumen. Figure 5 shows an arrangement where the tube does not have an inflation lumen. With such an arrangement the cuff 300 must be sufficiently self-inflating to ensure an effective seal with the inside of the trachea and it must also be capable of being compressed to smaller external dimensions during insertion and removal. The tube shown in Figure 5, instead of having an inflation lumen, includes a vent passage 301 from the inside of the cuff 300 to the outside of the shaft 1". This could be provided in various ways such as by means of a hole in the cuff itself or, as shown, by means of a shallow channel 301 along the outside of the shaft 1 " extending a short distance above and, or alternatively, below the cuff. In this way, air can escape from the inside of the cuff 300 when it is squeezed (such as when being inserted through a tracheostomy opening) and air can then flow into the cuff when its resilience applies an expansion force to it (such as when it enters the body cavity provided by the trachea). Such a cuff 300 may have an advantage in that, on an endotracheal tube, it could act to wipe secretions upwardly along the trachea when the tube is removed, since the cuff will be slid out in at least a partly-inflated state along the inside of the trachea.

The cuff need not be a separate component but could be formed with other parts of the tube. Figure 6 shows an arrangement where the foam part of the cuff 400 is formed integrally with a foam patient end tip 401 of the tube. A soft outer layer or skin 402 of a gas impervious material is subsequently applied to the outside of the entire length of the tube including the patient end tip 401, the cuff 400 and the main part of the tube shaft. In this arrangement several inflation lumens 403 extend along the tube shaft as channels along the outside of an inner component 404 that is covered by the outer skin 402. Figure 7 shows an arrangement similar to that of Figure 6 where the machine end flange 500 has a soft, foam surface 501 facing the patient that is enclosed by the outer impervious skin 502.

The invention is not limited to tracheal tubes but could be used on other cuffed tubes arranged to seal with other body spaces.

Claims

1. A medico-surgical tube including a shaft (1 , , 1 ") having a patient end (6) adapted for insertion within a body space and a sealing cuff (10, 120, 400, 510) mounted with the outside of the shaft towards its patient end adapted to provide a seal between the outside of the shaft and the inside of the body space, characterised in that the sealing cuff (10, 120, 400, 510) includes a part at least of a visco-elastic foam material (100, 200).

2. A tube according to Claim 1, characterised in that the foam material (100, 200) is of visco-elastic polyols.

3. A tube according to Claim 1 or 2, characterised in that the cuff (10) extends in

contact with the outer wall of the shaft (1).

4. A tube according to Claim 1 or 2, characterised in that the cuff (120) includes a wall of the visco-elastic foam material (200), and that the wall defines a space (204) between the outside of the shaft (1 ') and the inside of the wall when the cuff (120) is in an expanded state.

5. A tube according to any one of the previous claims, characterised in that the cuff (10, 120, 400, 510) includes a layer (101, 101 ' 402, 502) of an impervious material.

6. A tube according to Claim 5, characterised in that the layer (101, 402, 502) of

impervious material extends over an external surface of the cuff (101, 400, 510).

7. A tube according to Claims 4 and 5, characterised in that the layer (101 ') of

impervious material is on the inside surface of the cuff (120), and that the layer of impervious material (101) is bonded with the outside of the shaft (1 ').

8. A tube according to any one of the preceding claims, characterised in that the shaft (1, ) includes a lumen (12, 12') extending along the shaft and opening into the cuff (10, 120) by which gas can flow to or from the cuff to allow it to inflate and deflate.

9. A tube according to any one of Claims 1 to 7, characterised in that the tube includes a vent passage (301) opening into the cuff (300) to allow air to flow into and out of the cuff as it expands and contracts.

10 A tube according to any one of the preceding claims, characterised in that the cuff (400) of foam material is formed integrally with a foam patient end tip (401) of the shaft.

11. A tube according to any one of the preceding claims, characterised in that the cuff (510) of foam material is formed integrally with a foam surface (501) on a patient- facing surface of a flange (500) at the machine end of the tube.

12. A tube according to Claim 10 or 11, characterised in that the foam material is

covered by an outer layer (402, 502) of impervious material

13. A medico-surgical tube including a shaft (1 ') having a patient end adapted for

insertion within a body space and a sealing cuff (120, 300) attached with the outside of the shaft towards its patient end adapted to provide a seal between the outside of the shaft and the inside of the body space, characterised in that the sealing cuff (120, 300) includes a wall a part at least of which is formed of a foam material (200), and that the wall defines a space (204) between the outside of the shaft (1 ') and the inside of the wall when the cuff is in an expanded state.

14. A tube according to Claim 13 , characterised in that the wall of the cuff (120, 300) is between 0.5mm and 2mm thick.

15. A tube according to Claim 13 or 14, characterised in that the foam (200) is gas- permeable and that the cuff (120) includes a layer (10Γ) of impermeable material.

16. A tube according to Claim 15, characterised in that the layer (10Γ) of impermeable material is on the inner surface of the cuff (120, 300), and that the layer of impermeable material is bonded with the outside of the shaft (1 ', 1").

17. A tube according to any one of Claims 13 to 16, characterised in that the tube

includes a vent passage (301) opening into the cuff (300) to allow air to flow into and out of the cuff as it expands and contracts.

18 A tracheal tube according to Claim 17, characterised in that the cuff (300) is arranged such that it compresses during insertion into and removal from the trachea.

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