GB2436294A

GB2436294A - Laryngeal mask with malleable insert in airway tube

Info

Publication number: GB2436294A
Application number: GB0705249A
Authority: GB
Inventors: Stephen James Field; Richard Hingley; Caroline Therese Solly
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 2006-03-21
Filing date: 2007-03-19
Publication date: 2007-09-26
Anticipated expiration: 2027-03-19
Also published as: GB2436294B; GB0605669D0; GB0705249D0

Abstract

A laryngeal mask includes a strip 30 of malleable metal enclosed within the airway tube 1 to enable the machine end 12 of the mask to be bent and retain an angle relative to its patient end 10. The patient end of the malleable strip 30 is spaced from the patient end 10 of the mask to provide a more flexible region 31. The strip may be made from an alloy of zinc and iron and may be used in conjunction with a helical reinforcing element.

Description

LARYNGEAL MASK ASSEMBLIES

This invention relates to laiyngeal mask assemblies and their manufacture.

It is common practice to use an airway known as a laryngeal mask for administering anaesthetic and ventilation gases to a patient. These airways comprise a tube with an inflatable mask or cuff at one end, the tube being inserted in the patient's mouth so that one end is located in the hypopharynx and so that the mask forms a seal in this region with the surrounding tissue. Laryngeal masks are described in, for example, US5355879, US5305743, US5297547, US5282464, GB2267034, US524957 1, US524 1956, US5303697, GB2249959, GB2I 11394, EP448878, US4995388, GB2205499, GB2 128561, GB2298797, GB2334215, GB2337020, PCT/GBOO/03044, PCT/GBOO/03045, 0B0002805, 0B0020274, GB237 1990 and 0B0424579. 1. Laryngeal masks usually comprise a curved, extruded shaft, a separate mount member joined at the patient end of the tube and an inflatable cuff attached to the mount member. The shaft may be reinforced along its length with a helical reinforcing element such as a wire. It is also known, from US5682880, for a laryngeal mask to have a removable member extending along the entire length of the tube and projecting from the machine end of the tube to provide a handle while stiffening the tube.

Laryngeal masks have several advantages over endotracheal tubes, which are longer and seal with the trachea below the vocal folds. The shafts of conventional laryngeal masks tend to be relatively thick and stiff This leads to problems in that it can be easy to disturb the seal at the patient end of the mask, particularly if the patient is moved, such as during transport or when manipulated during surgery. Reinforced-shaft masks are less prone to this

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problem because they can be more flexible but these masks have their own problem in that their reduced axial stiffhess makes it more difficult to position their patient end correctly. The relatively large diameter of a laryngeal mask shaft can make it difficult to carry out procedures in the region of the mouth. Although flexible, reinforced tubes can be bent to one side they need to be anchored in place in some way, which may not always be convenient.

It is an object of the present invention to provide an alternative laryngeal mask assembly.

According to the present invention there is provided a laryngeal mask assembly comprising a tube and a sealing cuff extending around the patient end of the mount and adapted to seal in the region of the hypopharynx, the tube including an elongate malleable member enclosed within the tube extending along a region of the tube extending through the mouth opening such that the patient end of the malleable member is spaced from the sealing cuff by a flexible region of the tube.

The malleable member is preferably selected such that it can retain the machine end of the tube bent at an angle of substantially 900 to the remainder of the tube. The malleable member is preferably of a metal such as iron, aluminium or an alloy of zinc and iron. The malleable member is preferably a strip of material of substantially rectangular section. The strip of material may be curved across its width. The tube preferably has a natural curve along its length and the malleable member preferably extends in the plane of curvature of the tube. The malleable member may extend along the inside curvature of the tube. The tube may be reinforced by a helical reinforcing element.

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A laryngeal mask assembly 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 assembly; Figure 2 is a cross-sectional view across the tube of the assembly; Figure 3 illustrates the assembly in use with the machine end of the tube bent down, towards the chin; and Figure 4 illustrates the assembly in use with the machine end of the tube bent up towards the forehead.

The laryngeal mask assembly comprises an airway tube I and a conventional mask formation 2 at the patient end 10 of the tube having an annular sealing cuff 20 adapted to seal with patient tissue in the region of the hypopharnyx.

The tube I is of a bendable plastics material, such as PVC, and is curved along its length. A main, ventilation bore 11 extends along the tube from its patient end 10 to its rear, machine end 12. A small-bore lumen 13 extends within the wall of the tube 1 and communicates with the interior of the cuff 20, at the patient end 10, and with an inflation line and connector 14, towards the machine end 12 of the tube. Alternatively, the inflation line could itself extend to the mask such as along a channel formed along the exterior of the tube.

The tube I also includes a malleable member 30 extending within and totally enclosed by its wall. The malleable member 30 is in the form of an elongate strip of a malleable metal, such as iron, aluminium or a zinc-iron alloy. The strip 30 has a rectangular cross-section and is curved slightly across its width with the same radius of curvature "r" as that of the tube I. The width "w" of the strip 30 extends circumferentially of the tube 1 and its length is aligned longitudinally of the tube in the plane of its natural curvature and on the inside of its curvature. In this way, the preferential plane of bending of the strip 30, and hence of the tube 1 is in the same plane as the natural curve of the tube.

The malleable strip 30 extends along that part of the length of the tube 1 that, in use, extends through the opening of the mouth 40 so that the portion of the tube emerging from the mouth can be bent down towards the chin (caudally) as shown in Figure 3 or up towards the forehead (cephafadly) as shown in Figure 4. Typically, the bend is about 90 . The strip 30 only extends along the part of the length of the tube extending through the mouth opening, with the patient end of the strip being spaced from the mask 2 and patient end 10 of the tube.

This forms a region 31 of the tube 1 where the malleable strip 30 is absent and where the tube I is, therefore, more flexible. This is believed to be an advantage because, after insertion, it will allow for limited movement of the rear part 12 of the assembly with less risk of disturbing the seal at the patient end 10 of the assembly.

The malleable strip 30 allows the machine end 12 of the tube to be bent up or down afler insertion to a position where it will remain without the need for any additional support or fixing. The strip 30 also gives the major part of the tube 1 additional axial strength and

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rigidity so as to facilitate correct insertion and manipulation of the mask 2, whilst the flexible region 31 towards the patient end 10 allows for some relative movement between the mask and the rear part 12 of the tube.

The tube could be reinforced against lateral forces by the inclusion of a helical reinforcing member. This enables the tube to be made more flexible, such as by means of a thinner wall, since the helical reinforcing member will be effective to resist crushing and kinking when the tube is bent. Such a flexible tube would normally make insertion more difficult because it would be more difficult to apply axial pressure but, in the arrangement of the present invention, the presence of the malleable member provides the necessary axial strength. Helically-reinforced tubes also have the advantage that the wall thickness of the tube can be reduced, thereby enabling the external diameter of the tube to be reduced without affecting the diameter of the bore through the tube.

The malleable member could have any profile, it need not be rectangular but could, for example, be circular, oval or elliptical. The malleable member could be indented, in the manner described in GB2323534, to make it bend preferentially in one plane.

The malleable member need not be positioned to allow up/down or north/south bending of the machine end of the tube but could, instead, extend along a side of the tube to allow sideways or east/west bending. In some applications it might be advantageous to have two malleable members located diametrically opposite one another.

Claims

CLAIMS

1. A laryngeal mask assembly comprising a tube and a sealing cuff extending around the patient end of the mount and adapted to seal in the region of the hypopharynx, wherein the tube includes an elongate malleable member enclosed within the tube extending along a region of the tube extending through the mouth opening such that the patient end of the malleable member is spaced from the sealing cuff by a flexible region of the tube.

2. A laryngeal mask assembly according to Claim 1, wherein the malleable member is selected such that it can retain the machine end of the tube bent at an angle of substantially 900 to the remainder of the tube.

3. A laryngeal mask assembly according to Claim I or 2, wherein the malleable member is of a metal.

4. A laryngeal mask assembly according to Claim 3, wherein the malleable member is of iron, aluminium or an alloy of zinc and iron.

5. A laryngeal mask assembly according to any one of the preceding claims, wherein the malleable member is a strip of material of substantially rectangular section.

6. A laryngeal mask assembly according to Claim 5, wherein the strip of material is curved across its width.

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7. A laryngeal mask according to any one of the preceding claims, wherein the tube has a natural curve along its length, and wherein the malleable member extends in the plane of curvature of the tube.

8. A laryngeal mask according to Claim 7, wherein the malleable member extends along the inside curvature of the tube: 9. A laryngeal mask assembly according to any one of the preceding claims, wherein the tube is reinforced with a helical reinforcing element.

10. A laryngeal mask assembly substantially as hereinbefore described with reference to the accompanying drawings.

11. Any novel and inventive feature or combination of features as hereinbefore described with reference to the accompanying drawings.