WO2015107318A1

WO2015107318A1 - Medico-surgical tube with sealing arrangement

Info

Publication number: WO2015107318A1
Application number: PCT/GB2014/000503
Authority: WO
Inventors: Timothy Bateman; Stephen James Field; Andrew Thomas Jeffrey
Original assignee: Smiths Medical International Limited
Priority date: 2014-01-14
Filing date: 2014-12-05
Publication date: 2015-07-23
Also published as: GB201400566D0

Abstract

A tracheal tube (1, 401) has a self-expanding sealing cuff (20, 408) towards its patient end (13, 407). The cuff (20, 408) is held contracted when the tube is inserted and removed by an outer sleeve (21) or tube (400) that is slid forwardly to contract the cuff. The sleeve (21) or tube (400) is slid rearwardly to allow it to expand and seal with the trachea T. The cuff may be of a resilient foam or may have one or more resilient strips (22, 122, 221, 321) extending between two spaced support rings (24) and (25) and covered by an outer flexible sheath (26).

Description

MEDICO-SURGICAL TUBE WITH SEALING ARRANGEMENT

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 arrangement on 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 apparatus 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 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. 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, US5537729 and WO08/009947.

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 alternative apparatus.

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 arrangement includes a first part with a naturally expanded state and a second part that is displaceable relative to the shaft along a part at least of the length the shaft between a first position where it extends along the outside of the first part and holds the first part in a compressed state with lateral dimensions less than that of the body space to a second position where it does not extend along the outside of the first part, so that the tube can be inserted into and removed from the body when the second part is in the first position and the first part is compressed and so that the tube is sealed with the body space by the first part expanded to contact the surface of the body space when the second part is in the second position.

The second part may include a sleeve that is slidable over the first part of the sealing arrangement. The second part may include an actuation rod attached at one end with the sleeve and extending along the shaft to its opposite end where it is provided with a handle region by which the rod and sleeve can be displaced. In its second position the second part is preferably located to the machine side of the first part of the sealing arrangement away from the patient end. The first part may include one or more resilient mechanical members covered by a flexible sheath. The mechanical members may be provided by one or more elongate resilient strips extending between the two support rings, the length of the or each resilient strip being greater than the distance between the two support rings. The or each resilient strip may be of metal. The or each strip may be of a shape memory effect material. Alternatively, the first part may be of a resilient foam material.

According to another aspect of the present invention there is provided medico- surgical apparatus including an outer tube and an inner tube, characterised in that the inner tube has a patient end adapted for insertion within a body space and a sealing arrangement on the outside of the inner tube towards its patient end adapted to provide a seal between the outside of the inner tube and the inside of the body space, that the sealing arrangement has a naturally expanded state where it seals with a surface of the body space, that the inner tube and the outer tube are slidable lengthwise relative to one another such that the sealing arrangement is constrained in a contracted state during passage along the outer tube, and that the inner tube is longer than the outer tube so that its patient end and the sealing arrangement can locate beyond the patient end of the outer tube to allow the sealing means to expand into sealing contact with the body space.

The outer tube is preferably shorter than the inner tube. The sealing arrangement may be self-expanding. The apparatus may be a tracheal tube.

Different forms of tracheal 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 with a

compressed seal for insertion or removal;

Figure 2 shows the same tube with its seal in an expanded state during use;

Figure 3 is an enlarged side elevation view showing a first form of seal;

Figure 4 is an enlarged side elevation view showing a second form of seal;

Figure 5 is an enlarged side elevation view showing another form of seal;

Figure 6 is an enlarged side elevation view of a fourth form of seal; and Figures 7A and 7B show a modified tracheostomy tube in a removal/insertion and sealing state respectively.

With reference first to Figures 1 there is shown an endotracheal tube 1 having a curved shaft 10 with a bore 11 extending along its length. A sealing arrangement or sealing means 12, that will be described in greater detail later, is mounted on the outside of the shaft 10 towards its patient or distal end 13. The machine or proximal end 14 of the tube has a standard 15mm tapered connector 15 inserted in the shaft 10, which may be left open when the patient is breathing spontaneously or is connected to some form of ventilator when the patient needs assistance in breathing. In use, the patient end 13 of the tube is located in the patient's trachea T, with the sealing means 12 expanded to seal with the wall of the trachea, although Figure 1 shows the sealing means in an unexpanded condition. The machine end 14 of the tube 1 projects from the mouth of the patient.

The sealing means 12 is provided by a first, inner part 20 (Fig 2), which has a naturally expanded state, and a second, outer part 21 that is movable from a first position (shown in Figure 1) where it extends around the inner part and holds it in a compressed, contracted or unexpanded state, to a second position (shown in Figure 2) where it does not extend around the inner part so that this is able to expand to contact the tracheal wall.

The inner part 20 of the sealing means 12 can take various different forms but, in general, these rely on one or more mechanical members of an elastic or resilient nature covered by a flexible sheath. Such sealing means are self-expanding. The sealing means 12 shown in Figure 3 includes several metal strips 22 having multiple lateral extensions 23 of a wavy, sinusoidal, saw-tooth or zigzag configuration. The strips 22 extend longitudinally of the shaft 10 side-by-side spaced around the circumference of the shaft and are attached at opposite ends to respective annular support rings 24 and 25, which may be of a metal or plastics material. The strips 22 and support rings 24 and 25 are preferably assembled together before attaching to the shaft 10. The strips 22 and rings 24 and 25 could be formed of a single piece of material that is cut, such as by laser machining, punching or chemically etching. The support rings 24 and 25 are attached securely to the outside of the shaft 10 such as by means of an adhesive but the strips 22 extending between them are not attached to the shaft along their length, except via the rings themselves. In this way, the strips 22 are free to lift away from the outer surface of the shaft 10. The wavy shape of the strips 22 is such as to enable the length of the strips to expand freely when they lift away from the shaft. It will be appreciated that the length of material forming each strip 22 is greater than the distance between the support rings, thereby enabling the strip to expand longitudinally and outwardly of the shaft 10. The mechanical members need not be of a metal but could be of a shape memory polymer having a phase transition where the polymer changes from a frozen, folded state to a secondary unfolded state, such as the shape of an extruded sealing cuff.

The inner part 20 is completed by a flexible sheath 26 such as of a plastics material that extends along the shaft 10 on the outside of the rings 24, 25 and strips 22. The sheath 26 may be bonded to the rings 24 and 25, as shown, or it may extend a short distance beyond the rings and be bonded directly to the outside of the shaft 10. The sheath 26 may be elastic, with a natural diameter that ensures it lies close to the surface of the shaft 10 when the strips 22 lie close to the shaft. Alternatively, the sheath 26 may be relatively inelastic and formed with a natural shape that follows the expanded shape of the strips. In its natural state, therefore, the inner part 20 (formed of the strips 22 and sheath 26) bulges outwardly and makes light, sealing contact with the tracheal wall.

Before use, during insertion and removal, the inner part 20 is held in a compressed state by the outer part 21, which is in the form of a cylindrical sleeve 30 having a length approximately equal to that of the inner part and having an internal diameter slightly larger than the outer diameter of the shaft 10 and just sufficient to accommodate the inner part in a compressed state. The upper edge of the sleeve 30 is attached to the patient end of a rigid but bendable actuation rod 31 that extends longitudinally, rearwardly along the outside of the shaft 10 by a distance a little longer than the length of the sleeve. The rod 31 then extends through a channel 32 within the wall of the shaft 10 to a location close to the machine end 14 of the tube 1 where it emerges to provide a handle region 33. The actuation rod 31 enables the sleeve 30 to be displaced along the tube 1 by a short distance in either direction. In particular, the sleeve 30 can be pulled rearwardly, by gripping and pulling the handle region 33, to expose the inner part 20 and allow this to expand to the sealing position shown in Figure 2 where the sleeve is positioned to one side of the inner part 20 towards the machine end 14 and away from the patient end 13. The sleeve 30 can also be pushed forwardly, by pushing the handle region 33, to cover the inner part 20 and contract it to a smaller diameter (as shown by the position represented in Figure 1) so that the tube 1 can be inserted and removed from the trachea T.

In this way, the sealing means 12 on the tube 1 can be expanded (for sealing) and contracted (for insertion or removal). It will be appreciated that the interior of the sheath 26 may need to be vented to allow it to be expanded and contracted freely. This could be done by means of a vent hole in the sheath itself, by a hole though the shaft 10 into the bore 11 or by a vent passage along the shaft under the sealing rings 24 and 25 and opening on the outside of the shaft.

The inner part may have various different constructions. For example, as shown in Figure 4, the inner part 120 has a number of metal strips 121 similar to those shown in Figure 3 but having a lazy-tongs configuration of diagonal linked levers 122. This arrangement may have greater radial strength than the sinusoidal wave configuration shown in Figure 3.

The inner part arrangement 220 of Figure 5 has a number of straight, longitudinal strips 221 made of a shape memory effect alloy such as Nitinol. These strips 221 are arranged to lie flat against the surface of the tube shaft at low temperatures (below body temperature and preferably slightly below room temperature) so that they will expand after the sleeve is slid back and after the strips warm to body temperature. Figure 6 shows an arrangement 320 with a single strip 321 wound helically around the shaft. The strip 321 may be of a shape memory effect alloy or a conventional resilient material.

Instead of sliding a short sleeve over the sealing means to contract it during insertion and removal it would be possible instead to use a dual-tube arrangement of the kind shown in Figures 7 A and 7B. The apparatus includes an outer tracheostomy tube 400 and an inner tracheostomy tube 401 that is slidable along the outer tube. The machine end 402 of the outer tube 400 is terminated by a flange 403 by which the apparatus can be secured about the patient's neck. The patient end 404 of the outer tube 400 is uncuffed and terminates just above the location at which it is desired to make a seal with the trachea. The inner tube 401 is longer that the outer tube 400 and is terminated at its machine end 405 by a conventional 15mm tapered gas connector 406. The inner tube 401 carries on its outer surface, close to its patient end 407, some form of self-expanding sealing means 408, which may be similar to those shown in Figures 3 to 6. Instead of using a short slidable sleeve to hold the sealing means 408 in a contracted state during insertion, the outer tube 400 acts as a longer sleeve to hold the sealing means contracted as the inner tube 401 is slid inwardly along the outer tube, as shown in Figure 7A. When the patient end 407 emerges from the patient end 404 of the outer tube 400 the sealing means 408 is no longer constrained by the outer tube so it expands outwardly into sealing contact with the tracheal wall. The apparatus can be removed from the patient by gripping the protruding machine end 405 of the inner tube 401 and pulling it rearwardly so that the sealing means 408 contracts as it enters the outer tube 400 and can then be withdrawn by sliding rearwardly until it is fully enclosed. The inner and outer tubes 401 and 400 can then be removed from the patient together or the inner tube can be removed first, followed by the outer tube.

Instead of using an arrangement of mechanical members for the sealing means it might be possible to use a polymeric foam to provide the self-expanding force. The sealing means could incorporate a material with a snap-through change of state where it has two distinct structurally stable states, one that gives a small diameter to the sealing means and the other that gives a larger, sealing diameter. To change between these two states it might be necessary to apply a small inflation gas pressure temporarily (such as via an inflation lumen extending along the tube shaft), such as to cause a snap change from the small to the larger diameter. Once enlarged it would not be necessary to maintain the inflation pressure. To reduce the size of the sealing means for removal it would only be necessary to apply a small negative pressure, which would cause the sealing means to snap back to its original state.

The present invention can enable a constant sealing pressure to be exerted without the need for any cuff pressure monitoring devices. It also avoids the risk of sealing pressure increases caused by N₂O diffusion, which can happen in conventional gas-inflated sealing cuffs. The structure of the sealing cuff can enable its location to be readily identified using conventional imaging techniques, such as X-ray, fluoroscopy or MRI.

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

Claims

1. A medico-surgical tube (1, 401) including a shaft (10) having a patient end (13, 407) adapted for insertion within a body space (T) and a sealing arrangement (12, 408, 400) on 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 arrangement (12, 408, 400) includes a first part (20, 120, 220, 320, 408) with a naturally expanded state and a second part (21, 400) that is displaceable relative to the shaft (10) along a part at least of the length the shaft between a first position where it extends along the outside of the first part (20, 120, 220, 320, 408) and holds the first part in a compressed state with lateral dimensions less than that of the body space (T) to a second position where it does not extend along the outside of the first part (20, 120, 220, 320, 408), so that the tube (1, 401) can be inserted into and removed from the body when the second part (21, 400) is in the first position and the first part (20, 120, 220, 320, 408) is compressed and so that the tube (1, 401) is sealed with the body space by the first part (20, 120, 220, 320, 408) expanded to contact the surface of the body space when the second part (21, 400) is in the second position.

2. A medico-surgical tube according to Claim 1 , characterised in that the second part includes a sleeve (21, 400) that is slidable over the first part (20, 120, 220, 320, 408) of the sealing arrangement (12, 408, 400).

3. A medico-surgical tube according to Claim 2, characterised in that the second part (21) includes an actuation rod (31) attached at one end with the sleeve (21) and extending along the shaft (10) to its opposite end where it is provided with a handle region (33) by which the rod and sleeve can be displaced.

4. A medico-surgical tube according to any one of the preceding claims, characterised in that in its second position the second part (21, 400) is located to the machine side of the first part (20, 120, 220, 320, 408) of the sealing arrangement (12, 408, 400) away from the patient end (13, 407).

5. A medico-surgical tube according to any one of the preceding claims, characterised in that the first part (20, 120, 220, 320) includes one or more resilient mechanical members (22, 122, 221, 321) covered by a flexible sheath (26).

6. A medico-surgical tube according to Claim 5, characterised in that first part includes two support rings (24 and 25), that the mechanical members are provided by one or more elongate resilient strips (22, 122, 221, 321) extending between the two support rings, and that the length of the or each resilient strip (22, 122, 221, 321) is greater than the distance between the two support rings (24 and 25).

7. A medico-surgical tube according to Claim 6, characterised in that the or each

resilient strip (22, 122, 221, 321) is of metal.

8. A medico-surgical tube according to Claim 6 or 7, characterised in that the or each strip (22, 122, 221, 321) is of a shape memory effect material.

9. A medico-surgical tube according to any one of Claims 1 to 4, characterised in that the first part (20) is of a resilient foam material.

10. Medico-surgical apparatus including an outer tube (400) and an inner tube (401), characterised in that the inner tube (401) has a patient end (407) adapted for insertion within a body space and a sealing arrangement (408) on the outside of the inner tube towards its patient end adapted to provide a seal between the outside of the inner tube and the inside of the body space, that the sealing arrangement (408) has a naturally expanded state where it seals with a surface of the body space, that the inner tube (401) and the outer tube (400) are slidable lengthwise relative to one another such that the sealing arrangement (408) is constrained in a contracted state during passage along the outer tube, and that the inner tube (401) is longer than the outer tube (400) so that its patient end (407) and the sealing arrangement (408) can locate beyond the patient end of the outer tube to allow the sealing means to expand into sealing contact with the body space.

11. Medico-surgical apparatus according to Claim 10, characterised in that the outer tube (400) is shorter than the inner tube (401).

12. Medico-surgical apparatus according to Claim 10 or 11 , characterised in that the sealing arrangement (408) is self-expanding.

13. Medico-surgical apparatus according to any one of Claims 10 to 12, characterised in that the apparatus (400, 401) is a tracheal tube.