Airway device

Abstract

An airway device for human or animal use comprising an airway tube having a distal end and a proximal end, the distal end of which is surrounded by a laryngeal cuff, adapted to fit anatomically over the laryngeal structure of a patient, wherein the device optionally further comprises a buccal cavity stabilizer located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, said buccal cavity stabilizer being adapted to nest with the anterior aspect of the patient's tongue, the size, shape and configuration of the buccal stabilizer being adapted to prevent rotational or side-to-side movement of the airway device in use.

Claims

1. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by a laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of the patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the body of the buccal cavity stabiliser extends on both sides of the airway tube and is generally elliptical in cross-section, wherein the internal profile of the airway tube is substantially circular, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the device is formed at least in part by a transparent material whereby to permit an anaesthetist or operator to see an inner lumen of the airway tube.

2. The airway device according to claim 1, wherein the buccal cavity stabiliser comprises a region in which the profile of the airway tube is broadened.

3. The airway device according to claim 1, wherein the buccal cavity stabiliser is non-uniform in its width W, having a wide point located at a point intermediate the laryngeal cuff and the proximal end of the airway tube.

4. An airway device according to claim 1, wherein the height H of the buccal cavity stabiliser is substantially uniform along a longitudinal axis of the stabiliser.

5. The airway device according to claim 1, wherein the buccal cavity stabiliser has a first, ventral face in substantially the same plane as the plane of the open face of the laryngeal cuff and the first face of the buccal cavity stabiliser is substantially concave in shape.

6. The airway device according to claim 1, wherein the laryngeal cuff further comprises a lip located at the proximal end of the cuff, which is sized and shaped to hold the epiglottis back from folding towards the laryngeal inlet.

7. The airway device according to claim 1, wherein the face of the laryngeal cuff is formed from a material with a Shore hardness on the A scale of 40 or less.

8. The airway device according to claim 1, wherein the distal tip of the laryngeal cuff is so sized and shaped as to extend into the oesophageal inlet of the subject in use.

9. The airway device according to claim 1, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than a ventral portion.

10. The airway device according to claim 1, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

11. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by a laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of the patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the buccal cavity stabiliser is non-uniform in its width (W), having a wide point located at a point intermediate the laryngeal cuff and the proximal end of the airway tube, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the device is formed at least in part by a transparent material whereby to permit an anaesthetist or operator to see an inner lumen of the airway tube.

12. The airway device according to claim 11, wherein the height (H) of the buccal cavity stabiliser is substantially uniform along a longitudinal axis of the stabiliser.

13. The airway device according to claim 11, wherein the buccal cavity stabiliser has a first, ventral face in substantially the same plane as the plane of the open face of the laryngeal cuff and the first face of the buccal cavity stabiliser is substantially concave in shape.

14. The airway device according to claim 11, wherein the laryngeal cuff further comprises a lip located at the proximal end of the cuff, which is sized and shaped to hold the epiglottis back from folding towards the laryngeal inlet.

15. The airway device according to claim 11, wherein the face of the laryngeal cuff is formed from a material with a Shore hardness on the A scale of 40 or less.

16. The airway device according to claim 11, wherein the distal tip of the laryngeal cuff is so sized and shaped as to extend into the oesophageal inlet of the subject in use.

17. The airway device according to claim 11, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than a ventral portion.

18. The airway device according to claim 11, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

19. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by an inflatable laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of a patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the body of the buccal cavity stabiliser extends on both sides of the airway tube and is generally elliptical in cross-section, wherein the internal profile of the airway tube is substantially circular, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the device is formed at least in part by a transparent material whereby to permit an anaesthetist or operator to see an inner lumen of the airway tube.

20. The airway device of claim 19, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than a ventral portion.

21. The airway device according to claim 19, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

22. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by a laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of the patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the body of the buccal cavity stabiliser extends on both sides of the airway tube and is generally elliptical in cross-section, wherein the internal profile of the airway tube is substantially circular, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the airway tube is symmetrically positioned along a line of a central longitudinal axis of the device.

23. The airway device according to claim 22, wherein the buccal cavity stabiliser comprises a region in which the profile of the airway tube is broadened.

24. The airway device according to claim 22, wherein the buccal cavity stabiliser is non-uniform in its width (W), having a wide point located at a point intermediate the laryngeal cuff and the proximal end of the airway tube.

25. An airway device according to claim 22, wherein the height (H) of the buccal cavity stabiliser is substantially uniform along a longitudinal axis of the stabiliser.

26. The airway device according to claim 22, wherein the buccal cavity stabiliser has a first, ventral face in substantially the same plane as the plane of the open face of the laryngeal cuff and the first face of the buccal cavity stabiliser is substantially concave in shape.

27. The airway device according to claim 22, wherein the laryngeal cuff further comprises a lip located at the proximal end of the cuff, which is sized and shaped to hold the epiglottis back from folding towards the laryngeal inlet.

28. The airway device according to claim 22, wherein the face of the laryngeal cuff is formed from a material with a Shore hardness on the A scale of 40 or less.

29. The airway device according to claim 22, wherein the distal tip of the laryngeal cuff is so sized and shaped as to extend into the oesophageal inlet of the subject in use.

30. The airway device of claim 22, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than g ventral portion.

31. The airway device according to claim 22, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

32. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by a laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of the patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the buccal cavity stabiliser is non-uniform in its width (W), having a wide point located at a point intermediate the laryngeal cuff and the proximal end of the airway tube, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the airway tube is symmetrically positioned along a line of a central longitudinal axis of the device.

33. The airway device according to claim 32, wherein the height (H) of the buccal cavity stabiliser is substantially uniform along a longitudinal axis of the stabiliser.

34. The airway device according to claim 32, wherein the buccal cavity stabiliser has a first, ventral face in substantially the same plane as the plane of the open face of the laryngeal cuff and the first face of the buccal cavity stabiliser is substantially concave in shape.

35. The airway device according to claim 32, wherein the laryngeal cuff further comprises a lip located at the proximal end of the cuff, which is sized and shaped to hold the epiglottis back from folding towards the laryngeal inlet.

36. The airway device according to claim 32, wherein the face of the laryngeal cuff is formed from a material with a Shore hardness on the A scale of 40 or less.

37. The airway device according to claim 32, wherein the distal tip of the laryngeal cuff is so sized and shaped as to extend into the oesophageal inlet of the subject in use.

38. The airway device of claim 32, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than a ventral portion.

39. The airway device according to claim 32, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

40. A laryngeal mask airway device for human or animal use, said device comprising: (i) an airway tube having a distal end and a proximal end, wherein the distal end of the airway tube is surrounded by an inflatable laryngeal cuff adapted to form an anatomical fit over the laryngeal inlet of a patient and to cover and form a seal with the laryngeal inlet of a patient; and (ii) a buccal cavity stabiliser formed as an integral part of the airway tube, located on or around the airway tube between the laryngeal cuff and the proximal end of the tube, wherein the body of the buccal cavity stabiliser extends on both sides of the airway tube and is generally elliptical in cross-section, wherein the internal profile of the airway tube is substantially circular, wherein the laryngeal cuff and a front, ventral part of the buccal stabiliser are formed from a material of substantially the same Shore hardness, and wherein the airway tube is symmetrically positioned along a line of a central longitudinal axis of the device.

41. The airway device of claim 40, wherein a back or dorsal portion of the device and a front or central portion of the device are formed of materials of different Shore hardness in which the dorsal portion is made of a firmer material than a ventral portion.

42. The airway device according to claim 40, wherein a face of the buccal cavity stabiliser is roughened to increase friction of the stabiliser with the tongue when in use.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIGS. 1A to C illustrate various views of the laryngeal cartilages and ligaments. This illustration is derived from Tortora G. J., Grabowski G, Reynolds S. Principles of Anatomy and Physiology. John Wiley, 10th Ed, 2003. Pg 781, the text and illustrations of which are herein imported by reference;

(3) FIGS. 2 and 3 illustrate in plan view two embodiments of the present invention;

(4) FIGS. 4 to 7 illustrate two further embodiments with exploded views showing each airway device in two halves with an airway tube sandwiched between the halves;

(5) FIG. 8 shows an optional feature of a second passageway or tunnel starting at the lateral aspect of proximal end of NLA and curving towards the distal end to give its NLA tube/distal opening a posterior aspect of the NLA tube through the mask to allow passage of an orogastric tube;

(6) FIG. 9 shows a longitudinal slit running substantially the length of the mask to accommodate an endotracheal tube used in anticipated or unexpectedly difficult intubations; with or without the use of a bougie, Cook's airway or fibre-optic scope.

(7) FIGS. 10.1 to 10.6 show various plan, side and cross-sectional views of a further embodiment of the present invention.

(8) FIGS. 11, 12 and 13 show two frontal and one side or lateral view of a further embodiment according to the present invention in which the buccal cavity stabiliser is adjustable in size;

(9) FIG. 14 shows diagrammatically an airway device according to the present invention engaged over a laryngeal inlet;

(10) FIG. 15 illustrates a perspective view of a device in accordance with the present invention;

(11) FIGS. 16A to C illustrate cross-section and exploded diagram views of an airway device of FIG. 15, showing that the airway tube itself may stand proud of the main body of the device;

(12) FIGS. 17A to F show front, back, side and end elevational views of a further, preferred embodiment of the present invention;

(13) FIGS. 18A to D show front and side elevations of particularly preferred embodiments incorporating thin, flexible flanges around part of the circumference of the laryngeal cuff;

(14) FIGS. 19, 20 and 21 show various diagrammatic cross-sectional and isometric views of devices according to the present invention in situ in a human patient;

(15) FIG. 22 illustrates a section along the line Y-Y shown in FIG. 21.

(16) FIGS. 23A to C illustrate front, side and rear elevational views of an airway device according to a first embodiment of the present invention having a substantially circular profile airway tube;

(17) FIGS. 24A to D illustrate various perspective views of the embodiment shown in FIGS. 23A to C;

(18) FIGS. 25A to C show front, side and rear elevational views of an airway device according to a second embodiment of the present invention having a substantially elliptical profile airway tube;

(19) FIGS. 26A to D illustrate various perspective views of the embodiment shown in FIGS. 25A to C;

(20) FIGS. 27A to D illustrate various perspective views of an embodiment without a gastric tube passageway;

(21) FIGS. 28A to C illustrate front, side and rear elevational views of an airway device according to a further embodiment of the present invention;

(22) FIGS. 29A to D illustrate various perspective views of the embodiment shown in FIGS. 28A to C;

(23) FIGS. 30A to C show enlarged rear, side and front elevational views of a laryngeal cuff;

(24) FIG. 31 shows an enlargement of a cuff, detailing the split line between different plastics which would be present if the cuff is to be formed by materials of two different shore hardnesses;

(25) FIGS. 32A to D illustrate a connector which can also act as a bite protector; and

(26) FIG. 33 illustrates a front elevational view of a laryngeal cuff in which the gastric tube passageway exits on the mid-line or centrally from the tip of the cuff.

(27) FIGS. 34 to 40 show front, back, side and end elevational views of a further embodiment of the present invention;

(28) FIGS. 41 to 50 show front, back, side and end elevational views of another further embodiment of the present invention;

(29) FIGS. 51 to 57 show front, back, side and end elevational views of another further embodiment of the present invention;

(30) FIGS. 58 to 64 show front, back, side and end elevational views of another further embodiment of the present invention;

(31) FIGS. 65 to 71 show front, back, side and end elevational views of another further embodiment of the present invention; and

(32) FIGS. 72 to 78 show front, back, side and end elevational views of another further embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(33) Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the applicant although they are not the only ways in which this could be achieved.

(34) Referring to FIG. 2, this illustrates the distal end of a mask device according to a first embodiment of the present invention, generally shown as 10. This comprises an airway tube 11, which at its proximal end 12 (not shown) terminates in a 15 mm or other connector suitable for connection to an anaesthetic breathing system of conventional type. Formed around the distal end 13 of the airway tube is a laryngeal cuff or cup 14 adapted in its shape and contours to correspond with the larynx inlet region of a patient. In this context the terms cuff and cup have an equivalent meaning. They refer to the element of the device at the distal end of the airway tube that is adapted to cover and form a seal with the laryngeal inlet of the patient. In the context of this description, the term proximal means the end of the device, or portion thereof, closest to the connection to the anaesthetic breathing system. The term distal means the end of the device, or portion thereof, furthest from the anaesthetic breathing system.

(35) Laryngeal cuffs, in general, are well known to the specialist and the anatomy of the laryngeal inlet region of a human are shown in some detail in FIGS. 1A, B and C. The particular cuff shown in FIG. 2 incorporates in the cuff face pronounced and discernable bulges or protruberances 15, 16 designed to form a good seal with the piriform fossae and aryepiglottic folds. It will be appreciated that the outbulgings in the cuff at 15 and 16 are positioned antero-laterally to give an anatomical seal by fitting into the piriform fossae and aryetriglottic folds. Thus, in side elevation, the face of the cuff is not a flat planar surface but includes regions that protrude above the general plane of the cuff face. Additionally, there may optionally be regions which lie below the general plane of the cuff face. These shapings and the general size, shape and configuration of the surface of the cuff face around opening 17 are an important feature of the invention. Alternative shapes for the face of the cuff are shown in FIGS. 3, 5, 10, 11, 12, 17 and 18 and are described in more detail below.

(36) The device may be constructed from any suitable plastics material as selected by the materials specialist. Latex-free medical grade silicone rubber is one preferred material. The cuff should be soft in texture to avoid undue damage to the surrounding tissue. Other suitable materials for construction of this type of device include, but are not limited to, Poly Vinyl Chloride (PVC), Thermoplastic Elastomers such as the styrenic block copolymers (eg Styrene Butadiene Styrene (SBS), Styrene Ethylene Butylene Styrene (SEBS)), and Thermoplastic Olefin Blends (TPO), Thermoplastic PolyUrethanes (TPU), Copolyester (COPE), Polyether Block Amides (PEBAX) and foamed versions thereof, where appropriate.

(37) A further important factor involved in the choice of a suitable material is transparency. Ideally the material or materials of construction should be substantially clear or transparent. This enables the anaesthetist or operator to see the inner lumen of the airway to check for blockages or other problems. Such transparent materials are known to the materials specialist.

(38) In one preferred embodiment the cuff is non-inflatable and is formed from any suitable soft plastics material. By way of a preferred softness (hardness) range, on the Shore A scale of Hardness, a hardness of less than 40 for the face of the cuff that contacts the laryngeal inlet is optimum. By way of a preferred range, a value on the same scale of between 0 to 20 is preferred, with a particularly preferred range of 4 to 12. The softness of the cuff can be further adapted by forming cavities or channels within the body of the cuff itself (shown in FIGS. 4 and 5).

(39) In a further preferred embodiment the cuff may be pre-filled with a fluid such as air, or other non-toxic gas, or a non-toxic liquid. In this context the term fluid has a broad meaning and includes any suitable gas, liquid, vapour or combination thereof and will be determined and designed by an expert in this field of anatomy/anaesthesia in conjunction with the materials specialist. The cuff will be constructed of such a material which will not allow nitrous oxide (anaesthetic gas) to diffuse through the material to any significant amount so that the extra luminal pressure is kept constant. It follows therefore that the cuff should be substantially impermeable to the fluid with which is filled and to anaesthetic gases.

(40) Alternatively, the cuff can be formed from a soft, foamed material or can be foam filled. In either case this provides a soft deformable but shaped surface around the face of the cuff to engage over the anatomy of the larynx inlet region. Such a foam filled device will minimise any potential damage to the structures in that region whilst still providing a substantially complete seal.

(41) Directly adjacent to the laryngeal cuff/cup but positioned on the proximal side of the airway tube to the cuff itself is a buccal cavity stabiliser 20. In this example this stabiliser takes the form of an expanded region extending symmetrically on either side of the airway tube. This stabiliser is adapted to rest on the anterior aspect or front of the tongue and is configured to correspond with the anatomy of that part of the patient.

(42) A wide variety of shapes, sizes, and positions for this stabiliser are possible. The one illustrated in FIG. 2 is curved in the plane of the cuff face such that the face visible in FIG. 2 is slightly concave, with the rear face being slightly convex. The face of the stabiliser may be roughened, scored or serrated to increase the friction with the tongue and thus stabilise it in use, to avoid or reduce forward or backwards movements when in use.

(43) In this example the stabiliser is formed integrally with the cuff, such that one runs smoothly into the other. However, this is not essential and the stabiliser could be a separate unit on the airway tube. An essential feature of the stabiliser is that it is broader in cross-section than the diameter of the airway tube itself. That is to say it extends into a region either side of the airway tube and in the same generally plane as the laryngeal cuff. Preferred dimensions for the buccal cavity stabiliser will be discussed below.

(44) A further example of a different design of buccal cavity stabiliser is illustrated in FIGS. 11, 12 and 13. In this example the stabiliser 50 is adjustable and has two side hooks 51, 52 at the lateral aspects, near the proximal end of the airway tube, which can be slid downwards and upwards to increase or decrease the size of the flanges for adequate stability, and for the ease of insertion and removal of the NLA. The hooks engage into ratchet strips 53, 54, formed in opposing sides of the airway tube. The stabiliser is formed from a resiliently deformable, flexible material such that as the hooks are forced from their position as shown in FIG. 11 to a position closer to the cuff at the distal end of the tube, as illustrated in FIG. 12, the spread of the stabiliser on either side of the airway tube increases the more the hooks are moved towards the cuff, and therefore the broader the stabiliser. Thus the stabiliser extends from the proximal end of the airway tube, just below the connector to the proximal end of laryngeal cuff. The stabiliser is substantially symmetrical in shape and can be slid down to give an expanded shape across the buccal cavity. FIG. 13 shows an oblique lateral view of this embodiment.

(45) This is just one of the many methods which could be used to form a stabiliser. A stabiliser could be formed from any, preferably soft, extension around the airway tube wall that can lie on the anterior aspect of the tongue. Any suitably shaped laterally extending flange whose body lies mainly along the longitudinal axis of the airway tube would serve this purpose. The flange need not be solid, so a tubular, mesh or other perforated structure would be perfectly acceptable. The stabiliser preferably has a concave face or region when viewed from the direction shown in FIG. 11, ie from a direction normal to the face of the cuff, that conforms substantially to the anterior region of the tongue of the patient.

(46) It is also possible to form such a flange by broadening the profile of the airway tube at the appropriate region, just above the cuff. That is to say, the buccal cavity stabiliser may be an integral part of the airway tube, rather than being a separate component formed on or around the airway tube itself. Thus, a suitable increase in the general profile of the airway tube, whether formed by the tube itself or by forming additional material around the tube, can act as a stabiliser.

(47) The general profile of the buccal cavity stabiliser and the way that it merges smoothly into the cuff region can be seen in more detail from FIGS. 16 and 17A and B, which will be described in more detail below. However, it will be appreciated that both weight and plastics material would be saved if the internal diameter or profile of the airway tube increased and decreased correspondingly with the width of the buccal cavity stabiliser. The term internal profile is used because, as the airway tube broadens it becomes non-circular and instead assumes a substantially elliptical shape. It will therefore be appreciated that in this embodiment the cross-sectional area of the airway tube increases as the width of the buccal cavity stabiliser increase to its widest point and then decreases again. By maximising the width of the airway tube this has the potential to increase laminar flow within the device.

(48) A further feature of the airway device shown in FIG. 11 are the two sets of protrusions or bulges 56, 57 and 58, 59 on the face of the cuff. The larger of the two sets 56, 57 are adapted to around the aryepiglottic folds and in the pyriform fossae. The smaller of the two 58, 59 are adapted to fit around the Thyroid and Cricoid cartilages. In addition, the tip of the cuff 55 is a soft, tapered lip but is preferably not inflated.

(49) A further example is illustrated in FIG. 3. This illustrates an airway device 30 having a cuff 34 and a buccal cavity stabiliser 40. In this case there are two outbulgings or protrusions on either side of the cuff 35, 36, 38 and 39. An upper set, 38, 39 consisting of one protrusion on each side, is designed to lie around the aryepiglottic folds and in the pyriform fossae. The lower set 35, 36 are designed to lie around the thyroid and cricoid cartilages. The relative sizes of these bulges will be determined by the appropriate specialist. It is probable that the bulges 38 and 39, designed to fit around the aryepiglottic folds and in the pyriform fossae will be slightly larger than the two lower bulges. The distal/lower end of the cuff is soft but firm, and preferably not pre-inflated or pre-filled for the ease of the device's insertion, and adapted to lie in between the larynx and oesophagus. Further variations are shown in FIGS. 4 to 7, which show the flexibility possible within this general design concept. FIGS. 6 and 7 illustrate the possibility of including an additional moulding 60 on the proximal end of the unit.

(50) FIG. 5 illustrates one possible method of manufacture of a device according to the present invention. The device is manufactured from appropriate material as described previously in two halves 81 and 82. The two halves are bonded together around an airway tube 83 (not shown for clarity). The airway tube fits into a specially designed channel 84. In this example the buccal cavity stabiliser 90 is moulded integrally with the cuff 94. The tip of the device contains a series or plurality of cavities 91, 92 and 93. In this context plurality means one or more. These cavities increase the flexibility of the tip, which aids the insertion, and positioning of the device in use. These cavities also affect the softness and pliability of the tip, their presence making the tip softer than if it was formed from solid plastics material. Generally, the softer the material, the less potential there is to damage the tissue of the patient. The generally concave nature of the device is also apparent from FIGS. 4 and 5.

(51) A further feature in these embodiments which is apparent from these figures is that the distal tip of the device tapers to a gentle point. This tapered end is intended to lie or wedge between the larynx and the oesophageal inlet.

(52) An understanding of one method of constructing an airway device according to the present invention can be appreciated from FIGS. 4 to 7 inclusive. Basically, the device in FIG. 7 is formed in two parts 61 and 62 plus a moulding 64 which includes a 15 mm or other connector to connect the device to an anaesthetic breathing system. 61 is a ventral or front moulding, being that portion which comes into contact with the patient's laryngeal inlet and tongue. 62 is a dorsal or back moulding, being that side which faces away from the ventral portion. These definitions of ventral and dorsal are used throughout this specification.

(53) Optionally the device may also include a separate airway tube 63 that nests within channels 66, 67 formed within the internal body of mouldings 62 and 61 respectively. However, in a particularly preferred embodiment this separate tube 63 is omitted. In this example the tube 63 and mouldings 62 and 61 are made of silicone rubber and the mouldings 64 and 68 from polypropylene. The larger of the two polypropylene mouldings 68 is designed to prevent the device passing into the patient's mouth beyond a certain point.

(54) The airway tube may be of any appropriate diameter, or cross-section if the tube is not circular. Typically a 9 mm tube would be used in an adult version of the airway device.

(55) The mouldings 61 and 62 are bonded, glued, welded (including but not limited to heat welding and laser welding) or otherwise fixed together during assembly. It follows from this simple, elegant and cost-effective form of manufacture that the two components 61 and 62 can be formed from materials with different hardnesses. Thus the front portion of 61 that contains the laryngeal cuff can be made out of a softer material than the back portion. Typical Shore hardnesses on the A scale for the front portion 61 are between 0 to 20, more preferably 0 to 15 and more preferably 4 to 12.

(56) The rear portion 62 has typical Shore hardness values of 20 to 60 and more preferably 30 to 40.

(57) It is possible to incorporate an additional passageway 70 or passageways within the body of the unit and alongside the airway tube. An example of this is illustrated in FIG. 8. This passageway allows other tube(s) or wire(s) to be passed down the oesophagus during use without the need to move or disturb the device. For example, orogastric intubation now becomes possible.

(58) In another variant, shown in FIG. 9, the airway incorporates a longitudinal slit extending substantially the whole length of the passageway. This allows other tubes or wires (bougies, stylets etc) to be inserted or withdrawn during use without the need to disturb the mask, during planned or unexpected difficult intubations. Furthermore, this slit arrangement means that the airway device can be released from the tube or wire and removed from the patient leaving the tube or wire in place undisturbed.

(59) FIG. 10 shows a further embodiment of the present invention and also shows the generally curvilinear shape of the device along its longitudinal axis. This shape is designed to correspond with the mouth/throat opening in an anaesthetised patient. The longitudinal axis is the axis line shown as the straight dotted line in FIG. 10.4 and runs from the proximal and of the airway tube to the distal tip of the cuff.

(60) The general shape of one preferred embodiment of the buccal cavity stabiliser is shown in FIG. 10.3. The stabiliser, generally shown as 100, is formed around an airway tube 101. However, as described above, a separate tube is not necessary and a tubular passageway can be formed from channel(s) formed into the body of the stabiliser. The stabiliser portion extends 102, 103 on both sides of the tube 101 in a generally elliptical cross-section. It will be appreciated from FIGS. 10.1 and 10.5 and FIGS. 17 and 18 that the width of the buccal cavity stabiliser is non-uniform and varies along its length. This is in contrast to the airway tubes of similar prior art devices, which are generally uniform in cross-section. The width in this context is the edge-to-edge dimension in a direction normal to the longitudinal axis of the device and in a plane substantially parallel to the plane of the open face of the cuff. The stabiliser is narrowest at the proximal end of the device, then increases in width to a widest point, and then decreases in width again until it merges into the proximal side of the laryngeal cuff. The widest point of the stabiliser is therefore between the proximal end of the airway tube and the proximal end of the laryngeal mask. Generally it is advantageous if the widest part is nearer to the laryngeal mask end than it is to the proximal end, as shown in FIGS. 17A and B. This locates the widest part nearest to the anterior region of the patient's tongue in use.

(61) Importantly the height H of the stabiliser does not vary in a similar way. Rather the height remains substantially the same along the longitudinal axis of the stabiliser. This is quite different from conventional airway tubes.

(62) It will be evident from the foregoing that the width of the ellipse W at its widest point is greater than the height H at the same point. By way of example, for an adult airway device according to the present invention the width W of the stabiliser, at its widest point, would be in the range 3.5 cm to 4.5 cm and the height H would be in the range 1.25 cm to 1.75 cm. A preferred ratio of W:H is 2.710%.

(63) An important feature of the shape of this stabiliser is the profile of the upper 104 and lower 105 outer surfaces. These are both convex and gently curved in their broadest regions. This not only makes for ease of use but, more importantly, the lower surface 105 which comes into contact with the tongue in use, is profiled to follow the shape of the back of the patient's tongue and is soft enough to deform to conform to it.

(64) A further embodiment is illustrated in FIGS. 15 and 16A-16C. In this embodiment the airway tubing 111 is only partly contained within the body of the airway device 110. The distal end of the tube passes into and completely through the body of the device to form an opening within the cuff 113. In this embodiment a different profile of stabiliser is illustrated. In this case the lower surface 115, which contacts the tongue in use, is gently concave in shape, with the upper surface being generally convex.

(65) Once bonded together, the device becomes what is, in effect, a unitary construction. That is to say, the components become as one. This simplifies sterilization, if the devise is reusable, and increases reliability.

(66) However, unitary construction is not essential. For example, it may be possible to form the buccal cavity stabiliser as a separate component (not shown) that is threaded over, around or on to the airway tube if required. This design would give the anaesthetist the option of using the device with or without a stabiliser as desired. It would be necessary to incorporate some form of securing means to secure the stabiliser to either the cuff or the tube. Means of fixing or securing plastic components are well know, such as snap-fit connectors.

(67) This option increases the design options for the stabiliser. A form of leaf spring, secured at one or both ends to the airway tube could be employed. Alternatively an inflatable structure could be used. It will be recalled that inflatable cuffs have been used in this context. However, this type of technology has never been used before to incorporate a buccal cavity stabiliser into a device of this type.

(68) Two further embodiments are illustrated in FIGS. 17 and 18. These illustrate the streamlined, unitary construction of these embodiments of the invention, with the cuff region 121 merging smoothly into the buccal cavity stabiliser region 122. There are certain other key features shown in these Figures. For example, where the airway tube enters the laryngeal cuff, it does so through three separate apertures 123, 124 and 125. This greatly decreases the chance of the airway tube being blocked. The shape of the distal end of the stabiliser joining the proximal end of the cuff/cup is designed in such a way that when the device is in situ, it fits anatomically correctly in and around the valecullae.

(69) The distal tip of the cuff 126 has been truncated and in fact is now concave in shape. This results in less compressive pressures being exerted over the thyroid and cricoid cartilages, blood vessels and nerves supplying the laryngeal framework than is the case with prior art devices. This so-called concave tip can take a variety of different shapes and forms. The tip may be squared off such that the end of the tip is substantially planar. Or there may be a pronounced indentation in the tip, as shown in FIG. 17A. At the base of that indentation is an aperture forming the end of a gastric tube passageway described below. In summary, this truncation is intended to encompass any tip which results in less compressive pressure being exerted than by prior art devices.

(70) A second, gastric tube passageway, separate to the airway tube is provided which runs from an opening 127 in the proximal end of the device near the connector 128 to an opening in the distal tip of the cuff 129, more clearly shown in FIG. 17E. The gastric tube allows for any gastric aspirate to be detected in the event of passive regurgitation during use. It also provides a route for the insertion of small-bore gastric tubes (eg Freka Tubes).

(71) A further novel feature of this device is the lip or flange 130 located at the proximal end of the cuff region. This lip is sized and shaped so as to be anatomically positioned against the epiglottis, to ensure a proper seal and to hold the epiglottis back from folding towards the laryngeal inlet avoiding obstruction to airflow. This tip takes the form of a leaf like structure extending out of the laryngeal cuff and directed back towards the proximal end of the airway tube. Its relative size and shape can be seen from FIG. 17. The optimum size and shape will be determined by experimentation. The applicant is not aware of any prior art masks which contain this feature.

(72) FIGS. 18A to D also illustrate certain novel features of construction and of the laryngeal cuff. Turning first to the cuff, in this embodiment thin, flexible featherlike flanges 140 and 141 have been introduced on opposing sides of the cuff. These are preferably formed as an integral part of the moulding of the cuff and, because of the very soft nature of the material used to form the cuff, these flanges are particularly soft and pliable. Their purpose is to make allowance for any individual patient variation in the laryngeal inlet shape and to contribute to forming an efficient and effective seal between the cuff and the laryngeal structures. By this design, and by designing the cuff to be a close anatomical fit, the obtainable seal pressure from experimental trials is well in excess of 30 cm H.sub.2O.

(73) The feather-like flanges 140 and 141 are shown in FIGS. 18A to B as discontinuous structures but these can in fact be connected to each other towards the distal end of the cuff (FIGS. 18C and D). In this arrangement flanges 140 and 141 become a single U-shaped flange extending around the majority of the laryngeal cuff perimeter.

(74) Also shown in FIGS. 18A to D is a two-part form of construction. The two parts are an upper, curved portion 145, whose outer surface is generally convex and a lower curved portion 146 whose outer surface is generally concave and which includes the face of the laryngeal cuff which contacts the patient's laryngeal inlet in use. Formed within these two portions is an airway tube channel that extends from the proximal end 147 to the distal or cuff end 149, and the second passageway described above.

(75) The upper and lower parts are then bonded together around connector 150 by use of a suitable adhesive or welding technique as selected by the materials specialist.

(76) The upper portion 145 and the lower portion can advantageously be formed from materials having different Shore hardnesses. Thus, the upper portion can be formed of a material having a Shore hardness on the A scale in the range of 30 to 40, whereas the lower portion can be formed from a softer material with a hardness in the range 4 to 12 on the same scale.

(77) If required, the cuff region can be formed from a different material and of a different hardness, from other parts of the device. This arrangement is shown in FIG. 17C where the device is formed in three parts 135, 136 and 137 rather than two.

(78) However, the elegant and simple design of this airway device does allow for an even simpler method of manufacture. It has been discovered that the device can be moulded as a one-piece unitary construction in one mould. By constructing the mould appropriately, and by careful consideration of how the mould parts separate, one-piece manufacture is possible. The moulding may be produced using a process commonly known as 2 shot injection moulding, in which the materials are injected separately to form the relevant parts of the component. Alternatively, the component could be formed from material of the same hardness throughout using a single injection process, and if desirable overlain, in all or part of the ventral or dorsal section, with a material of differing Shore hardness. The technology for forming such overlay or laminates is known to those skilled in art.

(79) Turning now to the design of the laryngeal cuff, in the foregoing examples the cuff region has been pre-formed from a soft material, or pre-filled during manufacture with a fluid. In the latter case the lining of the cuff should be made from a material that does not absorb anaesthetic gases such as Nitrous Oxide, such that the pressure inside the cuff does not rise during use.

(80) In any alternative embodiment the cuff may be formed from a material which is adapted to absorb a liquid, such as water, mucous or blood or similar liquid material and in doing so to swell in size so as to confirm to the anatomical mucocartilagenous framework of the patient's laryngeal inlet. Such materials will be selected by the materials specialist but include CRM (cotton rayon mixes) as used in TAMPAX tampons, or compressed Gel Foam 5.

(81) In a further, alternative embodiment, the cuff could take the form of a conventional, inflatable cuff. Whilst this is not ideal, because of the inherent disadvantages of inflatable cuffs, the incorporation of a buccal cavity stabiliser of the type described above, made from soft materials as described above, into an inflatable laryngeal mask airway device represents a significant improvement over and above prior art inflatable masks. The technology to form an inflatable cuff is well known and need not be described here.

(82) In summary, the aims and objectives of the present invention are to provide an anatomically oriented, versatile, reliable, simple and cost effective device intended to be used in spontaneously breathing anaesthetized patients or patients recovering from anaesthetic, in certain group of intensive care patients during their weaning process and during resuscitation, to provide a secure, clear and hands-free airway for the delivery of oxygen and/or anaesthetic gases.

(83) Main aims and objectives are as follows: To provide a simplified design which has all the advantages of existing airway devices and has an anatomically oriented working mechanics in order to establish a clear airway in spontaneously breathing anaesthetized patients, patients in post-anaesthetic recovery phase or certain group of intensive care patients undergoing weaning off their ventilatory support. Avoids almost all the disadvantages and complications of currently used airway devices in anaesthetic practice. No need of laryngoscopy, intubation, or extubation and minimally invasive to pharyngo-larynx. User friendly, would require minimal training for anaesthetists, other doctors, nurses, paramedics and rest of the health care staff likely to use the device. A useful tool in the management of an unexpected or/and anticipated difficult endotracheal intubation. Useful either with an endotracheal tube through the airway or with planned Fibre-optic intubation or bronchoscopy. Self-retaining with hardly any need to tape or tie.

(84) In summary the device has a Connector, expanded glosso-pharyngeal flanges and a pre-formed, pre-inflated or pre-filled anatomically designed laryngeal cup or cuff suited to the exact contour and shape of the laryngeal inlet. However, this should not be seen to prevent this invention being used with a conventional, inflatable cuff.

(85) Connector:

(86) 15 mm ISO standard connector suitable to be connected with any of the gas delivery systems used in anaesthetic, during post-anaesthetic recovery, in intensive care and resuscitation practice.

(87) Expanded Glosso-Pharyngeal/Buccal Flanges:

(88) All the existing airways intubation devices have a varying degree of propensity to lateralize towards right or left angle of the mouth, rotation through 180 degrees about it's longitudinal axis and the movements of the airway inwards or outwards, which can lead to the displacement or misplacement of the distal end of the airway thus becoming ineffective for the purpose of it's use. A combination of the expanded flanges of the device, and constructing the device from a material of a Shore hardness less than 60 on the A scale, enables the buccal cavity stabiliser to act as an anchor for the airway device in the midline position by stretching over the anterior surface of the tongue across the buccal cavity and supported laterally by inner surface are aimed for better anchorage of the airway over the tongue. Thus, not only stabilizing the airway device positioned centrally but also stopping it to lateralize and/or rotate. Distally the expanded flange is incorporated into the flattened and angular part of the laryngeal cup with the postero-inferior surface of the tubular part of the device distally, in order to provide additional anchorage into the narrow hypopharynx.

(89) Anatomically Oriented Laryngeal Cup:

(90) A soft rubber or pre-formed, pre-inflated/pre-filled with a suitable liquid or soft material cup aimed not to exert an extra-luminal pressure of more than 22 mmHg onto the mucosa of Laryngeal inlet and adjacent structures thus avoiding any compression or shearing forces onto the pharyngo-laryngeal mucosa ensuring a continued, uninterrupted blood flow through the capillaries of the surrounding tissues, thus ensuring an uninterrupted blood supply of the structures in contact with it. Anatomically oriented laryngeal cup sealingly surrounds the laryngeal inlet without distorting the structures with which it is in contact.

(91) Laterally the out-bulgings of the cup or cuff are designed to fit around the pits of the Aryepiglottic folds and infero-laterally piriform fossae. The tapered lower end is for the ease of its passage through the oro-pharynx which will provide a seal over and beyond the interarytenoid fold in the midline and cuneiform and comiculate cartilages laterally. An upper midline slit will help the cup's passage over the epiglottis without damaging or folding and twisting the epiglottis into the cavity or distal opening of the device into the cup. Above the slit, is the flatter part of the soft cup which is designed for the optimal placement in the hypo-pharynx in between the epiglottis and the base of the tongue thus separating the surrounding structures away from the glottis. Although the cup provides a near natural and anatomical seal over the glottic opening but still prevention from the aspiration of regurgitated gastric contents cannot be guaranteed. Such risk could be minimized by using a modified device with an oesophageal component in high risk patients.

(92) Sizes:

(93) Sizes from 0-7 are envisaged.

(94) TABLE-US-00001 1 to 2 for neonates and infants (weight 3-20 kgs) 3 for children (weight 21-50 kgs) 4 to 5 for adolescents (weight 51-90 kgs) 6 to 7 for adults (weight more than 90 kgs)

(95) Re-usable or disposable devices may preferably be made of materials as described above such as latex-free SEBS or medically graded silicone rubber. A re-usable (sterilizable) device would be capable of at least 40 uses. The simplicity of the design also offers increased ease of sterilization for the purpose of its reuse. Disposable devices would be a preferred choice of production which will be not only more economical but also devoid of any risk of cross infection as may be the case in re-usable devices.

(96) As a result of the above design features a device according to the present invention, is likely to cost much less than any comparable device.

(97) NLA with Oseophageal Component

(98) Addition of an oesophageal component is intended to be used in patients with a suspicion of gastric statis under anaesthetics, in Intensive Care Units and for the patients with highly irritable airways who pose a well recognized and wide spread problem of weaning from ventilatory support. Such patients almost certainly end up with Tracheostomy in order to bypass their upper irritable airway, to facilitate weaning. Patients with chronic obstructive/restrictive airway disease, asthmatics and heavy smokers are the ones who are more likely to pose the weaning problem.

(99) Intubating NLA

(100) Morbidity or mortality in patients with an anticipated or/and unexpected difficult intubation is a well-recognized aspect of anaesthetic practice and a challenging nightmare for any anaesthetist when faced with that situation. A modified version of the NLA with a preformed longitudinal slit to the anterior of NLA will help facilitate intubation through the NLA with an endotracheal tube with the help of bougie, Cook's airway or a fibre-optic scope.

(101) Others

(102) Some modifications to the shape, design and working mechanics of each of the Component of the NLA are envisaged, whether needed for NLA's improved Performance or aesthetic look. The whole of the airway device could be manufactured as a single unit or each component of it manufactured separately if it is deemed necessary for the sake of its improved function or cost effectiveness or due to any other issue of practicality.

(103) It will be appreciated that, as used herein, the anatomical terms anterior and posterior, with respect to the human body, refer to locations nearer to the front of and to the back of the body, respectively, relative to other locations. In the context of this description, the term proximal means the end of the device, or portion thereof, closest to the connection to the anaesthetic breathing system. The term distal means the end of the device, or portion thereof, furthest from the anaesthetic breathing system or alternatively, the cuff end of the device. The term lateral refers to a location to the right or left sides of the body, relative to other locations. Bilateral refers to locations both to the left and right of the body, relative to other locations. The anatomical term medial or medially refers to a location toward the centre or midline of the body, relative to locations both to the left and right of the body.

(104) The airway devices described above have a soft laryngeal cuff adapted to fit anatomically over and form a seal with the laryngeal structure of a patient. An essential feature of these embodiments of this device is a so-called buccal cavity stabiliser, located around the airway tube, and which is designed to nest with the anterior aspect of the patient's tongue.

(105) The laryngeal cuffs on these devices are generally non-inflatable, but rather are formed from a soft, deformable material that can adapt to the individual detail of the patient's laryngeal inlet to form a satisfactory seal. It was precisely because of the very soft, deformable nature of these cuffs that it was considered necessary to incorporate some form of stabiliser to locate the cuff during insertion and to maintain a good gas-tight contact with the laryngeal inlet at all times during use. It should be borne in mind that use can involve the patient in many hours on the operating table under anaesthesia and can also involve use in accident and emergency situations involving hostile conditions that are non-ideal for such treatments.

(106) Referring to FIGS. 23A to C, which illustrate front, side and rear elevations of an airway device according to a first embodiment of a further aspect of the present invention, generally shown as 510. This comprises an airway tube 511, which at its proximal end 512 terminates in a 15 mm or other connector 518 suitable for connection to an anaesthetic breathing system of conventional type. Formed around the distal end 513 of the airway tube is a laryngeal cuff or cup 514 adapted in its shape and contours to correspond with the laryngeal inlet region of a patient. In this context the terms cuff and cup have an equivalent meaning. They refer to the element of the device at the distal end of the airway tube that is adapted to cover and form a seal with the laryngeal inlet of the patient in use. The anatomy of the laryngeal inlet region of a human is well known to the expert. It is illustrated in some detail in FIG. 1 and the key thereto.

(107) The cuff 514 has an opening 517 in a face or front region of the cuff and the back or dorsal part of the cuff is closed. The opening 517 in the face of the cuff connects directly to the airway tube 511 such that gas is free to flow from the connector 518 through the airway tube and out of the open face of the cuff.

(108) The particular cuff shown in FIGS. 23A to C incorporates in the cuff face pronounced and discernable bulges or protuberances 515, 516 designed to form a good substantially gas-tight seal with the piriform fossae and aryepiglottic folds. It will be appreciated that the outbulgings in the cuff at 515 and 516 are positioned antero-laterally to the laryngeal framework and give an anatomical seal by fitting into the piriform fossae and aryepiglottic folds and space postero-inferior to the thyroid and cricoid cartilages, and the posterior cartilages (corniculate and cuneiform). Thus, in side elevation, the face of the cuff is not a flat planar surface but includes regions that protrude above the general plane of the cuff face. Additionally, there may optionally be regions which lie below the general plane of the cuff face. These shapings and the general size, shape and configuration of the surface of the cuff face around opening 517 are an important feature of the invention.

(109) Thin, flexible, featherlike flanges 520 and 521 extend substantially around the circumference of the opening 517 in the face region of the cuff. These flanges are preferably formed as an integral part of the moulding of the cuff and, because of the very soft nature of the material used to form the cuff, these flanges are particularly soft and pliable. Their purpose is to make allowance for any individual patient variation in the laryngeal inlet shape and to contribute to forming an efficient and effective seal between the cuff and the laryngeal structures. By this design, and by designing the cuff to be a close anatomical fit, the obtainable seal pressure from experimental trials is well within the range of 12-40 cm H.sub.2O, which is sufficient for ventilation.

(110) These flanges need not completely encircle the opening 517 as shown in FIGS. 23A to C but it is preferred that they completely surround the opening circumference, and in doing so they follow the general contours of the front face of the cuff. Flanges 520 and 521 are spaced apart slightly such that each flange is an integral item or unit. The flanges are spaced radially one from another around the opening such that one flange surrounds another. The term radially in this context has a broad meaning and refers to the spacing of each flange from an imaginary axis extending out of the opening in a plane substantially perpendicular to the general plane of the cuff face.

(111) In this embodiment two feather flanges are shown. However, there may be no flanges, one flange or two or more than two flanges. In other words there may be none or a plurality of flanges, plurality having the meaning one or more in the context of this disclosure.

(112) A further feature of the cuff is the epiglottic rest 530 located at the proximal end of the cuff region. This epiglottic rest is sized and shaped so as to be anatomically positioned against the epiglottis, to ensure a proper seal and to hold the epiglottis back from downfolding towards the laryngeal inlet avoiding obstruction to airflow. This epiglottic rest takes the form of a leaf like structure extending out of the laryngeal cuff and directed back towards the proximal end of the airway tube. Its relative size and shape can be seen from 530A in FIG. 31. The optimum size and shape for this epiglottic rest will be determined by experimentation.

(113) Turning now to the airway tube, this is shown generally as 511 in FIG. 23. This tube, which is in the form of a hollow cylinder of substantially uniform cross-section open at each end, extends from the connector end 512 into the body of cuff 514 to connect with cuff opening 517. The inside diameter of the airway tube will depend on the size of the device, generally larger in adult sizes versus paediatric sizes, and designed in general to accommodate the appropriately sized endotracheal tube for endoscope guided intubation where necessary. The internal diameter of the tube may be substantially uniform along its length, although the internal diameter may vary.

(114) In terms of intubation the airway device also has significant benefits over inflatable laryngeal cuffs during retrograde intubation procedures. This is because inflatable cuffs can potentially be punctured and deflated, which could result in lack of seal and problems with ventilation.

(115) The tube is formed from a bendable plastics material that will be described in more detail below. With the exception of the region at the distal end of the tube where it starts to join the cuff, the external profile of the tube is substantially uniform between the distal end of the tube where it starts to meet the cuff and the proximal end of the tube. The term substantially uniform means that there is no region of the tube which could act as a buccal cavity stabiliser ie an expanded region extending on either side of the airway tube. Put another way, there is no section of the tube that extends on either side of the tube and which is generally broader in profile than the airway tube itself. The internal diameter of the airway tube will preferably be substantially uniform and circular, whether the tube has a circular or oval exterior profile, and the distal opening of the airway tube into the cuff is a single opening to help reduce the resistance to flow through the device.

(116) The airway tube can be formed with a variety of profiles. In the embodiment illustrated in FIGS. 23A to C and 24A to E the general external profile of the airway tube is substantially circular. This can be seen most clearly in FIG. 24D. In contrast, in the embodiment illustrated in FIGS. 25A to C and 26A to D, the airway tube has a generally elliptical external profile, although the bore passing through the airway tube is substantially circular in cross-section. These are just two of many profiles that might be selected by the designer.

(117) A connector 618 which fits into the end of the airway tube is shown in more detail in FIGS. 32A to D. There are two important features to note from this embodiment. Firstly, the length of the connector is significantly greater than a conventional connector and is such that it extends, in use, into the patient's mouth and beyond his/her teeth. In that way it acts as a bite protector and prevents the patient from inadvertently biting through the relatively soft material of the airway tube. The patient biting down onto the airway device and particularly or completely occluding airflow is a problem in certain procedures and with certain patients. Secondly, the connector fits into a recess formed within the airway tube by the moulding process. In this way, the internal surface of the airway tube 609 is substantially smooth and uniform. The internal diameter of the tube from the proximal opening in the connector to the distal end where it opens out into the cuff is substantially uniform. There is therefore no significant step change in internal diameter at the inner end of the connector, which leads to improved airflow and lower resistance to flow. This arrangement is shown particularly in FIG. 32C being a section along line E-E in FIG. 32B.

(118) In addition to the airway tube, the embodiments shown in FIGS. 23A to D, 24A to E, 25A to C, and 26A to D inclusive include a second passageway 540 that extends from an opening 542 in the distal end of the device to an opening 541 in the proximal end of the device. This second, gastric tube passageway, is designed to allow an operator to pass a gastric tube down into the stomach of a patient without interrupting anaesthesia, during EMS or during pre-hospital airway management. This second passageway also allows for detection of any gastric aspirate in the event of passive regurgitation during use. This second passageway must be large enough to allow a small bore gastric tube to pass easily through the device. Typically a gastric tube passageway would be between 6 to 14 French gauge diameter.

(119) The gastric tube passageway 540 and 640 shown in FIGS. 23A to C and 25A to C is shown housed substantially within the body of the airway device. However, it is also possible that this passageway could run externally of the new main body, for example laterally or along the dorsal face of the device body.

(120) Another feature of the passageways in these embodiments is that they are displaced to one side of the central longitudinal axis of the device, in this case to the right-hand side of the central longitudinal axis, as viewed from the open face of the cuff. However, the passageway, which is optional, could just as well exit along the mid-line or on the central longitudinal axis of the device as illustrated by 742 in FIG. 33.

(121) A further embodiment is illustrated in FIGS. 29A to D. In this example a laryngeal cuff is formed around a pre-formed or pre-cut piece of airway tube. This has the cost advantage that the airway tube may be formed from relatively inexpensive PVC tube or the like with a connector in one end and the cuff moulded over the other end. Once again the airway tube may be circular in profile or elliptical or any other profile as selected by the designer.

(122) FIGS. 23B and 25B and 28B amongst others show the generally curvilinear shape of the device along its longitudinal axis. This shape is designed to correspond with the mouth/throat opening in an anaesthetised patient. Whilst the device is flexible it is resiliently deformable and tends to return to this concave/convex shape in its unstressed state.

(123) In addition to passing tubes or other items through the gastric tube passageway, it is possible to pass items such as a guide wire directly into the trachea through the airway tube. To facilitate this the interior surface 650 of the cuff within the opening is ramped so as to direct a probe into the trachea (see FIG. 30C).

(124) The device may be constructed from any suitable plastics material as selected by the materials specialist. Latex-free medical grade silicone rubber is one preferred material. The cuff should be soft in texture to avoid undue damage to the surrounding tissue. Other suitable materials for construction of this type of device include, but are not limited to, Poly Vinyl Chloride (PVC), Thermoplastic Elastomers such as the styrenic block copolymers (eg Styrene Butadiene Styrene (SBS), Styrene Ethylene Butylene Styrene (SEBS)), and Thermoplastic Olefin Blends (TPO), Thermoplastic PolyUrethanes (TPU), Thermoplastic Vulcanisates (TPV), Copolyester (COPE), Polyether Block Amides (PEBAX), Melt Processable Rubbers, Flexible Co-polymers such as EVA, and foamed versions thereof, where appropriate.

(125) A further important factor involved in the choice of a suitable material is transparency. Ideally the material or materials of construction should be substantially clear or transparent. This enables the anaesthetist or operator to see the inner lumen of the airway to check for blockages or other problems. Such transparent materials are known to the materials specialist.

(126) By way of a preferred softness (hardness) range, on the Shore A scale of Hardness, a hardness of less than 30 for the face of the cuff that contacts the laryngeal inlet is optimum. By way of a preferred range, a value on the same scale of between 0 to 20 is preferred, with a particularly preferred range of 0 to 5. The apparent softness of the cuff can be further adapted by forming cavities or channels within the body of the cuff itself.

(127) In a further embodiment the cuff may be pre-filled with a fluid such as air, or other non-toxic gas, or a non-toxic liquid. In this context the term fluid has a broad meaning and includes any suitable gas, liquid, vapour or mixtures or combination thereof and will be determined and designed by an expert in this field of anatomy/anaesthesia in conjunction with the materials specialist. The cuff will be constructed of such a material which will not allow nitrous oxide (anaesthetic gas) to diffuse through the material to any significant amount so that the extra luminal pressure is kept constant. It follows therefore that the cuff should be substantially impermeable to the fluid with which is filled and to anaesthetic gases.

(128) Alternatively, the cuff can be formed from a soft, foamed material or can be foam filled. In either case this provides a soft deformable but shaped surface around the face of the cuff to engage over the anatomy of the laryngeal inlet region. Such a foam filled device will minimise any potential damage to the structures in that region whilst still providing a substantially complete seal.

(129) In the case of embodiments with a substantially circular airway tube and a gastric tube passageway which runs internally along the length of the device (as shown for example in FIGS. 23A to C and 24A to E), the centre of the bore of the airway tube can be displaced to one side of the central or mid-line axis of the airway tube itself. This displacement provides space for the gastric tube passageway to run alongside the bore of the airway tube. This arrangement is shown most clearly in FIG. 24D. The gastric tube passageway is, in effect, housed within the outer body of the airway tube. This arrangement makes for a neat, streamlined appearance in comparison to the arrangement in which the gastric tube passageway is external to or mounted on the back of the device.

(130) In terms of materials of manufacture and construction of an airway device according to the present invention, it is advantageous to form the front or open face of the cuff from a softer material than the remainder of the device. FIG. 23B shows a so-called split line 532 between the softer plastics material on the face of the cuff and slightly firmer material on the dorsal or back part of the cuff 519. The exact position of this split line may vary as determined by the designer. This line is shown in a slightly different position in FIG. 31, where it is shown as feature 632.

(131) By moving this split line towards the dorsal face of the cuff, this ensures that the sides of the cuff 533, 534 are also made of the softer material. The sides are therefore more easily deformed which contributes significantly to the ease of insertion, and removal, of the cuff during use. The cuff squeezes and seals into the space above the laryngeal inlet, cupping the laryngeal inlet to create a good seal for ventilation. As the cuff reduces in width and squeezes into position, the airway opening increases in depth. This increase in depth reduces the likelihood of the epiglottis occluding the airway during ventilation, a problem with prior art devices.

(132) Turning now to methods of manufacturing airway devices generally, and in particular airway devices according to the present invention, several new and cost-effective methods have been devised. These include injection moulding the device as a single unit using a one-shot or a two-shot process. Such methods also include extruding an airway tube and injection moulding a cuff around the tube in a one-shot or two-shot process.

(133) It follows therefore that the airway tube may be manufactured by extrusion or injection moulding and the cuff portion may be formed by one-shot or two-shot injection moulding.

(134) Accordingly, one method of making an airway device according to the present invention is to provide a mould, the mould including interior walls which define the shape of the airway device, and injecting into said mould a molten thermoplastic compound. Once cooled the item is ejected from the mould. In a further embodiment a two-shot process is used in which molten thermoplastic compound of a first hardness is first injected into the mould, which is retained in a pre-determined position such that only a pre-determined portion of the mould is filled with polymeric material. A second molten thermoplastic compound is then injected into the remaining space in the mould to complete the injection moulding process. In this manner the relatively firmer airway tube and dorsal portion of the cuff can be formed first and the relatively softer face of the cuff can be formed in the second part of the operation. Alternatively the face of the cuff can be formed first and the remainder of the device is formed in the second part of the operation.

(135) In an alternative method an airway tube is formed in a first step, either by extrusion or cutting a pre-determined length from a longer length of tubing. A mould defining a hollow space which will become the cuff region in the finished product is then placed around the airway tube and thermosetting plastic is injected into the mould in a one-step or a two-step process.

(136) In a third manufacturing embodiment a mould defining the cuff region is used to produce a cuff by either a one-step or a two-step injection moulding process. The cuff produced from this mould includes a recess adapted to accept an airway tube. In a separate operation or operations an airway tube is formed by extrusion or in some other manner. The airway tube is then inserted into and bonded to the recess provided in the cuff for that purpose.

(137) According to a further method of manufacture, the moulding process may be used to mould not only the laryngeal cuff on to the end of a pre-formed airway tube, but also a soft coating over the airway tube itself. Whilst this requires a larger mould, and more plastics material, it has the advantage that the finished device has a uniform finish over substantially the whole of its outer surface. It is softer for the patient and more aesthetically appealing for the operator. Having a pre-formed airway tube running most of the length of the device gives a degree of resilience and rigidity which is particularly helpful when using very soft plastics material.

(138) In terms of plastics materials used in these methods of manufacture, these will be determined by the materials specialist and are generally only limited by the ability to bond the chosen materials together. By way of example only, typically PVC can be used to mould the airway tube, the whole of the cuff region, the dorsal portion of the cuff region or any seals between these components. Polyolefins such as polyethylene and polypropylene or a polyurethane can be used to form the airway tube and/or the dorsal portion of the cuff region. A thermoplastic elastomer or a silicone rubber can be used to form the airway tube, the face of the cuff, the dorsal portion of the cuff, the whole of the cuff and any secondary seals therebetween.

(139) In this context the term bond has a particularly broad meaning. It encompasses any method or process in which two or more parts are permanently joined together. It includes, but is in no way limited to, molecular bonding, glueing using chemical adhesives, welding, including ultrasonic welding. The preferred method or methods of bonding will be selected by the materials specialist in this area.