Laryngeal mask

Abstract: A laryngeal mask airway has a tube (1) with a mask portion (13) at its patient end (14), the tube opening into the centre of the mask portion (13). The mask portion (13) is formed by a mount (15) attached to the tube (1) and by a bag-shape cuff (16) attached to the mount (15). The mount (15) is formed with two laterally-projecting flaps (31 and 32) defining a dumbbell-shape opening to the tube. The flaps (31 and 32) deflect the epiglottis during insertion of the airway into the patient but can be deflected by a suction tube, or the like, inserted through the tube (1).

Description: This invention relates to laryngeal mask assemblies of the kind comprising a tube with a mask portion at its patient end, the tube having an opening into the centre of the mask portion. It is common practice to use an airway known as a laryngeal mask for the administration of 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, US 5355879, US 5305743, US 5297547, US 5282464, GB 2267034, US 5249571, US 5241956, US 5303697, GB 2249959, GB 2111394, EP 448878, US 4995388, GB 2205499, GB 2128561 and GB 2298797. Laryngeal masks have several advantages over endotracheal tubes, which are longer and seal with the trachea below the vocal folds. One problem with laryngeal mask airways, however, is that there is a risk that the epiglottis can enter the air passage through the airway during insertion, thereby causing a blockage. In GB-A-2205499 there is described a laryngeal mask having bars extending across the patient-end opening of the tube into the mask, to prevent the epiglottis entering the opening. WO-A-97/12641 describes a laryngeal mask having a longitudinally-extending bar hinged to move the epiglottis when the bar is pushed forwardly by an inserted tube. It is an object of the present invention to provide an improved laryngeal mask assembly. According to the present invention there is provided a laryngeal mask assembly of the above-specified kind, characterised in that the mask portion has two flap members projecting laterally towards one another across a part only of the opening, so as to deflect the epiglottis away from the opening during insertion, and that the flap members are deflectable by an elongate member inserted along the tube. The flap members may provide a dumbbell shape to the opening. The mask portion may comprise a mount member attached with the tube and a cuff attached with the mount member, the flap members being formed from the material of the mount member. The cuff may be a bag-shape member attached with the mount member adjacent the flap members. A laryngeal mask airway assembly according to the present invention, will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a side elevation view of the assembly; Figure 2 is a sectional side elevation view of the patient end of the assembly to an enlarged scale; and Figure 3 is a view from below of the patient end of the assembly. The assembly comprises a bendable tube 1 of a plastics material, such as PVC, with a coupling 10 at its machine end 12. The tube 1 is curved along its length and has a mask portion 13 at its patient end 14. The tube 1 is extruded with an inflation lumen 2 within its wall. The lumen 2 is connected towards the machine end of the assembly to an inflation line 3 with an inflation indicator and connector 4. The opposite, patient end of the inflation lumen 2 opens into the mask portion 13. The mask portion 13 comprises a mount member 15 and a flexible bag member 16. The mount member 15 is moulded from a bendable plastics material, such as PVC. The mount member 15 has a hollow cylindrical sleeve 17 at its rear end, in which the forward, patient end 14 of the tube 1 is inserted and joined. The forward, patient end 18 of the mount member 15 is of an inverted dish shape with a generally elliptical or egg-shape outline and with a concave recess 19. The peripheral edge 20 of the mount member 15 is curved rearwardly to form a convex peripheral forward surface 21 lying on a flat plane inclined at an angle of about 30° to the axis of the patient end of the tube 1. The sleeve 17 has a bore 22 at its rear end communicating with the passage through the tube 1, and opens at its forward end into the recess 19. The bag member 16 is blow moulded from a flexible, resilient plastics material, such as PVC, polyurethane, silicone, EVA, TPE, polyether block amide or the like. The bag 16 has a sock shape with an open ankle or neck portion 23 at its upper, rear end and an egg shape lower, forward foot portion 24 shaped with the same general outline as the mount member 15. The bag 16 encompasses the forward end of the assembly, enclosing the entirety of the mount 15 and having its neck 23 attached to the outside of the forward end 14 of the tube 1, such as by solvent, adhesive or welding. The bag 16 is also attached to the concave recess 19 of the mount 15 along an annular band 26 extending around the opening of the bore 22, to seal the bag material to the mount. A hole 27 in the bag 16 provides an opening to the bore 22 in the mount member 15. The bag 16 provides an inflatable cuff at the forward end of the assembly and communicates with the inflation lumen 2 by means of an opening 28 cut through the outer surface of the tube 1 below the point where the bag is attached to the tube. The mount member 15 also has an epiglottis deflector provided by two flaps 31 and 32, formed from the material of the mount member, just behind the hole 27 in the bag 16. The flaps 31 and 32 extend parallel to the plane containing the forward surface 21 of the mount member 15 and project laterally inwardly towards the major axis of the elliptical shape of the end of the mount member. The flaps 31 and 32 are of approximately semicircular shape and, at their closest separation, are spaced by a small gap 33. In this way, the opening into the tube 1 is divided into two pear-shape regions 34 and 35 separated by the gap 33, giving the opening into the bore through the tube a dumbbell or keyhole shape. The stiffness of the material forming the two flaps 31 and 32 is sufficient to deflect the epiglottis during insertion of the mask assembly, but the flaps bend readily to allow a suction catheter, or the like to be inserted along the tube 1 and project from the mask portion.

Claims: A laryngeal mask assembly comprising a tube (1) with a mask portion (13) at its patient end (14), the tube (1) having an opening into the centre of the mask portion (13), characterised in that the mask portion (13) has two flap members (31 and 32) projecting laterally towards one another across a part only of the opening, so as to deflect the epiglottis away from the opening during insertion, and that the flap members (31 and 32) are deflectable by an elongate member inserted along the tube. A laryngeal mask assembly according to Claim 1, characterised in that the flap members (31 and 32) provide a dumbbell shape to the opening. A laryngeal mask assembly according to Claim 1 or 2, characterised in that the mask portion (13) comprises a mount member (15) attached with the tube (1) and a cuff (16) attached with the mount member (15), and that the flap members (31 and 32) are formed from the material of the mount member (15). A laryngeal mask assembly according to Claim 4, characterised in that the cuff is a bag-shape member (16) attached with the mount member (15) adjacent the flap members (31 and 32).

Inventors: PAGAN ERIC, PAGAN, ERIC
Applicants: SMITHS GROUP PLC
Application year: 1998
Main classification: A61M16
IPC codes: A61M16