Patent Publication Number: US-2021162155-A1

Title: Airway device

Description:
FIELD OF THE INVENTION 
     The present invention relates to medical devices, namely airway devices. It is applicable to supraglottic devices including laryngeal airway devices and to their methods of manufacture. The present invention is particularly applicable to laryngeal airway devices for human and veterinary use. 
     BACKGROUND OF THE INVENTION 
     Various Supraglottic, Periglottic, Intraglottic and Extraglottic airway devices are known and are currently used in establishing and/or maintaining a clear airway for the provision of Oxygen and/or anaesthetic gases during spontaneous breathing or IPPV in anaesthetised patients, or for resuscitation applications. The main focus of developments in such devices has heavily leaned towards ensuring the best shape and material combination to make such devices easy to insert and to improve sealing pressures once the device is in situ within the patient. 
     A problem that still exists in present supraglottic devices, and in particular in laryngeal airway devices, is the possibility of the epiglottis of the human or animal patient down folding and partially or completely occluding the airway within the device, thus blocking off the gas flow to and from the patient. The problem associated with down folding epiglottis is most applicable to paediatric and animal patients who have a large range in both the flexibility and size of the epiglotti. 
     In addition, in the case of inflatable devices when the device is inflated it inflates to fill the available space, which can also include filling the space around the laryngeal inlet thus squashing the laryngeal inlet inwards and occluding the airway it is aiming to maintain, especially in the case of paediatric humans, female humans and in small animal patients. 
     Also in case of inflatable devices when the device is inflated and also in the case of some non-inflatable supraglottic airway devices, the device may buckle in front of the region of the glottis and the laryngeal inlet which may partially or completely obstruct the flow of oxygen and other gases to and from of the breathing apparatus. 
     The main focus of recent developments in such devices has moved away from inflatable devices and instead heavily leaned towards the formation of the cuff from a soft pad from a material with a very low Shore Hardness on the A scale. 
     US2016/0317768 (NASIR), GB2413963 (NASIR) and US2015/0000672 (JASSELL, NASIR) each describe airway devices with a non-inflatable cuff which is pre-formed to fit over and with the laryngeal frame work of a patient. This means that there is contact between the cuff and the laryngeal frame work of a patient. The cuff is formed from a pad of soft material which provides for a soft deformable pad with a shaped surface to engage over and with the anatomy of the larynx inlet region. The engaging surface of the pad is essentially a mirror image of the structure of and around the larynx such that a face to face constant pressure compression seal is formed between the surface of the pad and the structures of the larynx. 
     US2018/0177964 (ZHU) describes another airway device with a non-inflatable cuff which is pre-formed to fit over and with the laryngeal frame work of a patient. This means that there is contact between the cuff and the laryngeal frame work of a patient. The cuff is formed from a pad of soft material which provides for a soft deformable pad with a shaped surface to engage over and with the anatomy of the larynx inlet region. The engaging surface of the pad is essentially a mirror image of the structure of and around the larynx such that a face to face constant pressure compression seal is formed between the surface of the pad and the structures of the larynx. 
     US2011/0023890 (BASKA) describes an airway device with a non-inflatable cuff, which again is designed to fit over and with the laryngeal frame work of a patient. This time instead of having a shaped surface formed from a pad of soft material, a hollow pad (or chamber) is provided which is formed from a resilient material. The surface of the hollow pad (or chamber) is able to deform to form a seal with the larynx. In this airway device the hollow pad (or chamber) is in fluid communication with the airway tube and is able to “inflate” and “deflate” with a bellows action when gas moves through the airway tube when intermittent positive-pressure ventilation (IPPV) is employed. This means that a face to face dynamic compression seal is formed between the resilient surface of the hollow pad and the structures of the larynx. 
     US2008/0099026 (CHANG) describes an airway device with a non-inflatable cuff which is also designed to fit over and with the laryngeal frame work of a patient. This time instead of a hollow pad (or chamber) a resilient web is provided with a planer sealing surface. The planer surface of the resilient web is able to deform to form a seal with the larynx. This means that a face to face compression seal is formed between the planar sealing surface of the resilient web and the structures of the larynx. 
     WO2012/127436 (MILLER) describes an airway device with a non-inflatable cuff, which again is designed to fit over and with the laryngeal frame work of a patient. This time instead of having a shaped surface formed from a pad of soft material, a hollow pad (or chamber) is provided which is formed from a resilient material. The surface of the hollow pad (or chamber) is able to deform to form a seal with the larynx. In this airway device the hollow pad (or chamber) is in fluid communication with the airway tube and is able to “inflate” and “deflate” when gas moves through the airway tube when intermittent positive-pressure ventilation (IPPV) is employed. This means that a face to face dynamic compression seal is formed between the resilient surface of the hollow pad and the structures of the larynx. 
     The problem with using such pads of soft material (whether they are solid pads of material, or foam pads of material, or hollow pads of material, or resilient webs with planar sealing surfaces) is that in order to create a good seal the pad of material needs to be compressed. No matter how soft the material is used, the more the pad is compressed the harder the material will become in the confined space naturally available around the larynx in the pharynx of the human or animal patient. In addition, there is also a maximum amount that the material can be compressed before it can no longer be compressed without a substantial force being exerted upon it. 
     Furthermore, all of these prior art devices form a seal with structures of the larynx such as the laryngeal inlet of a patient, and the inflation and compression forces exerted by all of these prior art devices risk damaging the delicate structures of the larynx and the peri-larynx that they are forming their compression seals with and also risks displacing airway structures such as the epiglottis which may result in a blocking of the airway of the human or animal patient. 
     This problem is set out and discussed in “Airway Management Evolution—In a Search for an Ideal Extraglottic Airway Device, Pavel Michalek, Donald M. Miller, Prague Medical Report/Vol. 115 (2014) No. 3-4, p. 87-103”. This report sets out that in traditional airway devices as airway pressure rises, a pressure gradient is generated from inside to outside. This may constitute a force for expelling the device. Dislodgement of the device is likely to occur at the peak of inspiration. Factors that prevent that dislodgement are two-fold: Frictional forces and the direction of forces generated by the sealing mechanism in relation to the expulsive force. In the case of the inflatable devices, the frictional force of the device being hooked around the base of the tongue is the main means of preventing it being expelled. The sealing forces related to the cuff are not perpendicular to the expulsive force as is the case with base of-tongue sealing devices, which is mechanically advantageous. In the case of the inflatable devices which as well as the main inflatable cuff have the addition of a cuff on the back of the peri-laryngeal seal to assist in correcting this imbalance to make a more effective seal, where the expulsive forces are perpendicular to the sealing force. The publication goes on to say that base-of-tongue sealers such as SLIPA, which is described in WO0232490, seal with forces that are perpendicular to the expulsive force and hence they seal at higher inflation pressures. 
     Therefore, all of these traditional prior art airway devices create pressures in and around the delicate structures of the larynx and the peri-larynx that they are forming their compression seals with, and which they are at risk of damaging. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided an airway device for human or animal use, the device comprising an airway tube having a distal end and a proximal end, the distal end of the airway tube is provided with a pre-formed and non-inflatable peri-pharyngeal bowl, the peri-pharyngeal bowl comprising a posterior bowl portion having a back dorsal portion and a side wall extending around and depending from the periphery of the back dorsal portion to define an internal space, the peri-pharyngeal bowl further comprising a resiliently deformable flange extending laterally from the side wall of the back dorsal portion which defines an extended internal space, the resiliently deformable flange having inner and outer surfaces that extend to a circumferential edge. 
     Preferably the circumferential edge is provided with a circumferential lip. 
     Preferably the circumferential edge is rounded or curved such that it is blunt and does not have any square edges. 
     Preferably the circumferential lip is rounded or curved such that it is blunt and does not have any square edges. 
     Preferably the resiliently deformable flange forms a generally ovoid shape, preferably the circumferential edge forms a generally ovoid shape, preferably the circumferential lip forms a generally ovoid shape. 
     Preferably the circumferential lip is formed by providing the circumferential edge with a bend towards to the outer surface of the circumferential edge, preferably the bend is 70° to 90°. Alternatively, the circumferential lip is a separate component connected to the outer surface of the circumferential edge. 
     Alternatively the circumferential lip is formed by providing the circumferential edge with a bend towards to the inner surface of the circumferential edge, preferably the bend is 70° to 90°. Alternatively, the circumferential lip is a separate component connected to the inner surface of the circumferential edge. 
     Alternatively the circumferential lip is formed on both sides of the circumferential edge to create a combined circumferential edge and circumferential lip with a larger overall width or footprint than the thickness of the resiliently deformable flange. 
     Preferably the circumferential lip is the same depth and thickness as the thickness of the resiliently deformable flange. 
     Preferably the resiliently deformable flange splays outwardly upon application of a force. 
     Preferably the resiliently deformable flange splays outwardly upon application of a force when in situ in a human or animal patient. 
     Preferably the resiliently deformable flange forms an impaction seal when in situ in a human or animal patient. 
     In the case of the present invention an impaction seal is created when pressure is transmitted from contact of the back dorsal portion of the airway device with the posterior pharyngeal wall of the human or animal patient when the device is in situ in the human or animal patient, the pressure is then transmitted first through the side wall, and then through the resiliently deformable flange such that the resiliently deformable flange, circumferential edge and circumferential lip if present, impact against the tissues with which the resiliently deformable flange forms the seal. 
     Preferably in the case where the resiliently deformable flange splays outwardly upon application of a force a portion of the internal surface of the resiliently deformable flange forms the seal when in situ in a human or animal patient. 
     Preferably the resiliently deformable flange forms a seal with the peri-larynx in the hypopharynx also known as laryngopharynx of the human or animal patient, preferably by enveloping the glottis in particular within the peri-pharyngeal bowl, more preferably the body of the larynx in general when in situ in a human or animal patient. The peri-larynx is the area around the larynx. Preferably the seal is an impaction seal, preferably the seal is created by a constant impaction seal, preferably the seal is not dynamic. In one alternative a portion of the internal surface of the resiliently deformable flange forms a seal with the peri-larynx in the hypopharynx. 
     The body of the larynx of the human or animal patient connects the inferior part of the pharynx (hypopharynx) with the trachea and is generally in the shape of a hollow tube. An exemplary illustration of the body of the larynx of the human or animal patient is illustrated in  FIGS. 50 to 52 . The body of the larynx of the human or animal patient comprises six cartilages, three unpaired and three paired. The unpaired cartilages comprise the thyroid cartilage  1  (which forms the Adam&#39;s apple), the cricoid cartilage  2  which forms the inferior wall of the larynx and the epiglottis  3  which varies in shape depending on the species, which forms a lid over the glottis (the opening running through the centre of the body of the larynx). The paired cartilages comprise the arytenoid cartilages  4  which influence the tension and position of the vocal cords, the corniculate cartilages  5  which are located at the apex of each arytenoid cartilage and the cuneiform cartilages  6  which are located anterior to the corniculate cartilages  5 . 
     Preferably the circumferential edge of the resiliently deformable flange forms a seal with the peri-larynx of the human or animal patient when in situ in a human or animal patient. The peri-larynx is the area around the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. In one alternative a portion of the internal surface of the resiliently deformable flange forms a seal with the peri-larynx of the human or animal patient when in situ in a human or animal patient. 
     Preferably when the device is in situ in a human or animal patient the circumferential edge has a very small area of contact with the mucosae of base of the tongue, peri-larynx, piriform fossae and upper oesophagus which causes the least amount of pressure trauma, and also maintains blood supply to the mucosae. 
     Preferably the circumferential lip of the circumferential edge forms a seal with the peri-larynx of the human or animal patient when in situ in a human or animal patient. The peri-larynx is the area around the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. 
     Preferably when the device is in situ in a human or animal patient the circumferential lip has a very small area of contact with the mucosae of base of the tongue, peri-larynx, piriform fossae and upper oesophagus which causes the least amount of pressure trauma, and also maintains blood supply to the mucosae. 
     Preferably the resiliently deformable flange forms a seal within the pharynx and the hypo-pharynx of the human or animal patient when in situ in a human or animal patient by enveloping the glottis in particular and the whole body of the larynx in general. The pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharynx is the part of the throat that lies beside and around the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. In one alternative a portion of the internal surface of the resiliently deformable flange forms a seal within the pharynx and the hypo-pharynx of the human or animal patient when in situ in a human or animal patient by enveloping the glottis in particular and the whole body of the larynx in general. 
     Preferably the circumferential edge of the resiliently deformable flange forms a seal with the pharynx and the hypo-pharynx of the human or animal patient when in situ in a human or animal patient. The pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharynx is the part of the throat that lies beside and around the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. 
     Preferably the circumferential lip of the circumferential edge forms a seal with the pharynx and the hypo-pharynx of the human or animal patient when in situ in a human or animal patient. The pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharynx is the part of the throat that lies beside and around the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. 
     Preferably the resiliently deformable flange forms a seal within and against the mucosa of the pharyngeal and hypo-pharyngeal walls of the human or animal patient when in situ in a human or animal patient. The pharyngeal wall is a wall of the pharynx, the pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharyngeal wall is a wall of the hypo-pharynx, the hypo-pharynx is the part of the throat that lies beside and behind the larynx. Preferably the seal is a impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. The mucosa is a mucous membrane that lines the various cavities in the body and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue, contained within are small bore, thin walled blood capillaries (which are easily collapsible with only a little compression) that supply the blood to the delicate and easily compressible mucosa. In one alternative a portion of the internal surface of the resiliently deformable flange forms a seal within and against the mucosa of the pharyngeal and hypo-pharyngeal walls of the human or animal patient when in situ in a human or animal patient. 
     Preferably the resiliently deformable flange forms a substantially continuous ovoid seal with the flattest areas of the mucosa to the front, back and sides of the body of the larynx. 
     Preferably the circumferential edge of the resiliently deformable flange forms a seal within and against the mucosa of the pharyngeal and hypo-pharyngeal walls of the human or animal patient preferably without compromising the blood supply when in situ in a human or animal patient. This is advantageous over the excessive pressures and vector forces applied and exerted by inflatable and padded devices which may compromise the blood supply to the mucosa by causing exsanguination and compression trauma leading to hypoxic tissue damage leading to inflammation, oedema, swelling, infection, sore throat, dysphagia and desloughing of the damaged mucosa. The pharyngeal wall is a wall of the pharynx, the pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharyngeal wall is a wall of the hypo-pharynx, the hypo-pharynx is the part of the throat that lies beside and behind the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. The mucosa is a mucous membrane that lines the various surfaces of the pharynx, larynx, hypopharynx and laryngopharynx. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue that have intertwined within thin walled, easily collapsible network of blood capillaries of arterial and venous webbing to supply and drain away blood. 
     Preferably the circumferential edge of the resiliently deformable flange forms a substantially continuous ovoid seal with the flattest areas of the mucosa to the front, back and sides of the body of the larynx. 
     Preferably the circumferential lip of the circumferential edge forms a seal within and against the mucosa of the pharyngeal and hypo-pharyngeal walls of the human or animal patient preferably without compromising the blood supply when in situ in a human or animal patient. This is advantageous over the excessive pressures and vector forces applied and exerted by inflatable and padded devices which may compromise the blood supply to the mucosa by causing exsanguination and compression trauma leading to hypoxic tissue damage leading to inflammation, oedema, swelling, infection, sore throat, dysphagia and desloughing of the damaged mucosa. The pharyngeal wall is a wall of the pharynx, the pharynx is the area of the throat behind the mouth and nasal cavity and above the oesophagus and larynx and the hypo-pharyngeal wall is a wall of the hypo-pharynx, the hypo-pharynx is the part of the throat that lies beside and behind the larynx. Preferably the seal is an impaction seal, preferably the seal is a constant impaction seal, preferably the seal is not dynamic. The mucosa is a mucous membrane that lines the various surfaces of the pharynx, larynx, hypopharynx and laryngopharynx. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue that have intertwined within thin walled, easily collapsible network of blood capillaries of arterial and venous webbing to supply and drain away blood. 
     Preferably the circumferential lip of the circumferential edge forms a substantially continuous ovoid seal with the flattest areas of the mucosa to the front, back and sides of the body of the larynx. 
     Preferably the combined internal space, being the internal space and the extended internal space, contains and envelopes 50% to 100% of the body of the larynx of the human or animal patient, preferably without making contact therewith once the airway device is in situ in a human or animal patient. 
     Preferably the combined internal space, being the internal space and the extended internal space, contains and envelopes 70% to 90% of the body of the larynx of the human or animal patient once the airway device is in situ in a human or animal patient. 
     Preferably the combined internal space is configured to not only contain the glottis and the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained, preferably without narrowing the natural size and shape of the glottis, laryngeal inlet and overall body of the larynx, that there is still sufficient space in the combined internal space which is enveloping the body of the larynx for gases to freely flow to and from the glottis of the patient without being impeded by the body of the larynx. Preferably in this case the whole of the body of the larynx is contained within the combined internal space. 
     Preferably the internal space defined by the side walls of the of the back dorsal portion of the peri-pharyngeal bowl contains 50% to 100% of the body of the larynx of the human or animal patient, preferably without making contact therewith once the airway device is in situ in a human or animal patient. This means that even if the resiliently deformable flange is completely deformed such that the extended internal space defined by the resiliently deformable flange is no longer present the internal space defined by the side walls of the back dorsal portion of the peri-pharyngeal bowl is sufficiently sized itself to contain 50% to 100% of the body of the larynx of the human or animal patient, preferably without making contact therewith once the airway device is in situ in a human or animal patient. 
     Preferably the resiliently deformable flange is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl. Preferably the depth of the resiliently deformable flange is configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the resiliently deformable flange is greatest at the proximal end of the peri-pharyngeal bowl and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl. Preferably the depth of the resiliently deformable flange at the middle of the peri-pharyngeal bowl is about half to about two thirds that of the proximal end of the peri-pharyngeal bowl. Preferably the depth of the resiliently deformable flange at the proximal end of the peri-pharyngeal bowl is about a quarter to about a third that of the distal end of the peri-pharyngeal bowl. 
     Preferably the thickness of the resiliently deformable flange is uniform, alternatively the resiliently deformable flange is of predetermined variable thickness. 
     Preferably the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point. The fact that the resiliently deformable flange is much thinner than the cuffs in prior art non-inflatable devices means that they are more flexible and can be readily deformed when required. In particular, the fact that the resiliently deformable flange of the peri-pharyngeal bowl is readily deformable means that the peri-pharyngeal bowl can be made to be larger overall than the non-inflatable cuffs of prior art airway devices as the resiliently deformable flange of the peri-pharyngeal bowl can be readily deformed to pass through structures, such as the faucial pillars (also known as pharyngoepiglottic folds and ostium in Guinea pigs), which in the past have led to a reduced size of laryngeal cuff in other devices. As the airway device is inserted into the human or animal patient, the peri-pharyngeal bowl comes into contact with the faucial pillars; the resiliently deformable flange of the peri-pharyngeal bowl then deforms allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl has passed beyond the faucial pillars, the resiliently deformable flange of the peri-pharyngeal bowl and thus the peri-pharyngeal bowl itself regain their original shapes. As the dimensions of the peri-pharyngeal bowl are larger than seen in the cuffs of non-inflatable prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV without causing or exerting any excessive pressures to the mucosae of the human or animal patient&#39;s pharynx or peri-larynx. The seal that is created is a combination of a compression seal and an impaction seal rather than a suction seal like the seal that is created by a plunger used in plumbing and denture manufacturing. 
     Preferably in a device for a guinea pig the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 10% to 13% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably in a device for a rabbit the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 5% to 10% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably in a device for a cat the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 5% to 10% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably in a device for a dog the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 5% to 10% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably in a device for a horse the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 5% to 10% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably in a device for a human the thickness of the resiliently deformable flange of the peri-pharyngeal bowl is about 1% to 5% of the external width of the peri-pharyngeal bowl at its widest point. 
     Preferably the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 1 mm to about 15 mm, preferably thickness of the side wall varies between about 0.5 mm to about 12 mm, preferably the thickness of the resiliently deformable flange is between about 0.5 mm to about 5 mm. 
     Preferably in a device for a guinea pig the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 1 mm to about 3 mm, preferably thickness of the side wall varies between about 0.5 mm to about 1.5 mm, preferably the thickness of the resiliently deformable flange is between about 0.5 mm to about 1.5 mm. 
     Preferably in a device for a rabbit the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 1.5 mm to about 3 mm, preferably thickness of the side wall varies between about 0.5 mm to about 1.5 mm, preferably the thickness of the resiliently deformable flange is between about 0.5 mm to about 1 mm. 
     Preferably in a device for a cat the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 2 mm to about 4 mm, preferably thickness of the side wall varies between about 2 mm to about 4 mm, preferably the thickness of the resiliently deformable flange is between about 1 mm to about 2.5 mm. 
     Preferably in a device for a dog the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 6 mm to about 10 mm, preferably thickness of the side wall varies between about 3 mm to about 6 mm, preferably the thickness of the resiliently deformable flange is between about 1 mm to about 3 mm. 
     Preferably in a device for a horse the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 8 mm to about 15 mm, preferably thickness of the side wall varies between about 8 mm to about 12 mm, preferably the thickness of the resiliently deformable flange is between about 2 mm to about 5 mm. 
     Preferably in a device for a human the thickness of the back dorsal portion of the peri-pharyngeal bowl is between about 2.5 mm to about 15 mm, preferably thickness of the side wall varies between about 5 mm to about 10 mm, preferably the thickness of the resiliently deformable flange is between about 1 mm to about 4 mm. 
     In essence the thickness of the walls of the resiliently deformable flange are thinner than the side walls of the posterior bowl portion of the peri-laryngeal bowl. 
     The transition in the thickness between the side wall and the resiliently deformable flange may be graduated or it may be stepped. 
     The fact that the resiliently deformable flange is much thinner than the cuffs in prior art non-inflatable devices means that they are more flexible and can be readily deformed when required. In particular, the fact that the resiliently deformable flange of the peri-pharyngeal bowl is readily deformable means that the peri-pharyngeal bowl can be made to be larger overall than the non-inflatable cuffs of prior art airway devices as the resiliently deformable flange of the peri-pharyngeal bowl can be readily deformed to pass through structures, such as the faucial pillars (also known as pharyngoepiglottic folds and ostium in Guinea pigs), which in the past have led to a reduced size of laryngeal cuff in other devices. As the airway device is inserted into the human or animal patient, the peri-pharyngeal bowl comes into contact with the faucial pillars; the resiliently deformable flange of the peri-pharyngeal bowl then deforms allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl has passed beyond the faucial pillars, the resiliently deformable flange of the peri-pharyngeal bowl and thus the peri-pharyngeal bowl itself regain and bounce/spring back into their original shapes. As the dimensions of the peri-pharyngeal bowl are larger than seen in the cuffs of non-inflatable prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV without causing or exerting any excessive pressures to the mucosae of the human or animal patient&#39;s pharynx or peri-larynx. The seal that is created is a combination of a compression seal and an impaction seal rather than a suction seal like the seal that is created by a plunger used in plumbing and denture manufacturing. 
     Preferably the peri-pharyngeal bowl is provided with a tip at the distal end of the peri-pharyngeal bowl. Preferably the tip of the peri-pharyngeal bowl is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient to provide a secondary seal to reduce/prevent regurgitation which in turn reduces/eliminates the risk of aspiration pneumonia. 
     Preferably the exterior of the posterior bowl portion is provided with rounded square corners between the exterior of the back dorsal portion and the side walls of the posterior bowl portion. The rounded square corners provide support and stability to prevent peri-pharyngeal bowl from rocking side to side when in situ in the human or animal patient. 
     Preferably the exterior of the posterior bowl portion is provided with a flattened back dorsal portion. The flattened back dorsal portion provides support and stability to prevent peri-pharyngeal bowl from rocking side to side when in situ in the human or animal patient. It does this by resting against the domed roof of the pharynx to resist rotation about the longitudinal axis thus stabilising the device. 
     Preferably the airway device is further provided with a gastric tube passageway, preferably the gastric tube passageway extends along the length of the device exiting through tip of peri-pharyngeal bowl. Preferably the posterior bowl portion houses the gastric tube passage way as it passes through the peri-pharyngeal bowl. Preferably the back dorsal portion of the posterior bowl portion houses the gastric tube passage way as it passes through the peri-pharyngeal bowl. 
     Preferably the device is further provided with a connector for connecting the device to a gas supply. The gas supply may be oxygen, air, anaesthetic gas etc. 
     Preferably the device is formed from a single shot of plastics material over moulded around the connector. Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     In one alternative the connector is formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector is formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector is formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In another alternative the connector is formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     Preferably the connector is provided with a loop, ring or other member which when over moulded prevents the removal of the connector from the airway tube of the device without also destroying the airway tube of the device. In one alternative the connector is a reduced or low dead space connector. 
     Essentially the invention provides for a thin walled flexible bowl structure that sits over the top of the larynx and seats on either side of the larynx forming a seal. The airway device comprises a relatively strong bowl that stays open to maintain the airway with a deformable flange structure that is able to flex to pass through the oral and pharyngeal structures and then seal on the floor of the pharynx. By using a bowl formed from a thin material means that a device can be formed of a single material wherein the wall thickness can be varied to provide strong areas and flexible areas. Using a single material eliminates the risk of glue or other bonding failure. 
     Existing supraglottic airway devices function by pressing the structure directly onto the larynx or both the larynx and epiglottis as described in the background of the invention above. This technique does not recognise that the larynx is a structure that rises up (dorsally) into the pharynx with a strip of pharyngeal mucosa to either side of the larynx rather than the larynx being an integral part of the pharynx. 
     The distinction between the airway device of the present invention and the supraglottic airway devices of the prior art is the location where the seal is formed. The present invention uses the strips of mucosa in front of, behind and to either side of the larynx/epiglottis to press the seal edge down onto. This is marked by the dots indicated in  FIG. 49 . 
     The existing supraglottic airway devices do not take account of the complex three-dimensional structure of the larynx, instead, they rely on compressing these structures flat against the floor of the pharynx until a relatively flat surface is achieved that they can seal against. 
     The present invention does not attempt to form a seal against the laryngeal structures, instead it uses the existing flat surfaces in front and behind the larynx and the sloped pharyngeal surfaces to either side to seal against. The larynx then extends into the combined internal space in the peri-pharyngeal bowl of the airway device which has been made large enough to completely encompass the body of the larynx, leaving space above (dorsal) and to the side (lateral) for airflow. 
     The walls of the resiliently deformable flange that form the seal have to be thin for this to work, as the space between the lateral pharyngeal wall and the larynx is slim (of varying width in different species). The thicker walls and pads of the prior art airway devices cannot fit into this space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
       The invention will now be described, by way of example only, with reference the accompanying drawings in which: 
         FIG. 1  is a top (dorsal) view of an airway device according to a first embodiment of the present invention; 
         FIG. 2  is a bottom (ventral) view of an airway device according to a first embodiment of the present invention; 
         FIG. 2 a    is a cross-sectional view through A-A of  FIG. 2 ; 
         FIG. 2 b    is a cross-sectional view through A-A of  FIG. 2  illustrating the position of the thickness of the back dorsal portion of the peri-pharyngeal bowl (a) the thickness of the side wall (b) and the thickness of the resiliently deformable flange (c); 
         FIG. 3  is a side view of an airway device according to a first embodiment of the present invention; 
         FIG. 4  is a side cross-sectional view through B-B of  FIG. 2 ; 
         FIG. 5  is a perspective bottom (ventral) view of an airway device according to a first embodiment of the present invention; 
         FIG. 6  is a top/bottom (dorsal/ventral) view of the connector of an airway device according to the first embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of the connector through C-C of  FIG. 6 ; 
         FIG. 8  is a front-end view of the connector of an airway device according to the first embodiment of the present invention; 
         FIG. 9  is a perspective view of the connector of an airway device according to the first embodiment of the present invention; 
         FIG. 10  is a top (dorsal) view of an airway device according to a second embodiment of the present invention; 
         FIG. 11  is a bottom (ventral) view of an airway device according to a second embodiment of the present invention; 
         FIG. 11 a    is a cross-sectional view through A-A of  FIG. 11 ; 
         FIG. 11 b    is a cross-sectional view through A-A of  FIG. 11  illustrating the position of the thickness of the back dorsal portion of the peri-pharyngeal bowl (a) the thickness of the side wall (b), the thickness of the resiliently deformable flange (c) and the footprint of the circumferential lip and resiliently deformable flange (d); 
         FIG. 12  is a side view of an airway device according to a second embodiment of the present invention; 
         FIG. 13  is a cross-sectional view through B-B of  FIG. 11 ; 
         FIG. 14  is a bottom (ventral) perspective view of an airway device according to a second embodiment of the present invention; 
         FIG. 15  is a top/bottom (dorsal/ventral) view of the connector of an airway device according to the second embodiment of the present invention; 
         FIG. 15 a    is a cross-sectional view through C-C of  FIG. 16 ; 
         FIG. 16  is a side view of the connector of an airway device according to the second embodiment of the present invention; 
         FIG. 16 a    is a cross-sectional view through D-D of  FIG. 16 ; 
         FIG. 17  is a perspective view of the connector of an airway device according to the second embodiment of the present invention; 
         FIG. 18  is a front-end view of the connector of an airway device according to the second embodiment of the present invention; 
         FIG. 19  is a top (dorsal) view of an airway device according to a third embodiment of the present invention; 
         FIG. 20  is a bottom (ventral) view of an airway device according to a third embodiment of the present invention; 
         FIG. 20 a    is a cross-sectional view through A-A of  FIG. 20 ; 
         FIG. 20 b    is a cross-sectional view through A-A of  FIG. 20  illustrating the position of the thickness of the back dorsal portion of the peri-pharyngeal bowl (a) the thickness of the side wall (b), the thickness of the resiliently deformable flange (c) and the footprint of the circumferential lip and resiliently deformable flange (d); 
         FIG. 21  is a side view of an airway device according to a third embodiment of the present invention; 
         FIG. 22  is a cross-sectional view is a cross-sectional view through B-B of  FIG. 20 ; 
         FIG. 23  is a bottom (ventral) perspective view of an airway device according to a third embodiment of the present invention; 
         FIG. 24  is a top/bottom (dorsal/ventral) view of the connector of an airway device according to the third embodiment of the present invention; 
         FIG. 24 a    is a cross-sectional view through C-C of  FIG. 24 ; 
         FIG. 25  is a side view of the connector of an airway device according to the third embodiment of the present invention; 
         FIG. 25 a    is a cross-sectional view through D-D of  FIG. 25 ; 
         FIG. 26  is a perspective view of the connector of an airway device according to the third embodiment of the present invention; 
         FIG. 27  is a front-end view of the connector of an airway device according to the third embodiment of the present invention; 
         FIG. 28  is a top (dorsal) view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 29  is a bottom (ventral) view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 29 a    is cross-sectional view through A-A of  FIG. 29  illustrating the position of the thickness of the back dorsal portion of the peri-pharyngeal bowl (a) the thickness of the side wall (b), the thickness of the resiliently deformable flange (c) and the footprint of the circumferential lip and resiliently deformable flange (d); 
         FIG. 30  is a side view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 31  is a side cross-sectional view through B-B of  FIG. 29 ; 
         FIG. 32  is a bottom (ventral) perspective view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 33  is a top (dorsal) perspective view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 34  is a top/bottom (dorsal/ventral) exploded view of the connector of an airway device according to the fourth embodiment of the present invention; 
         FIG. 35  is an exploded side view of the connector of an airway device according to the fourth embodiment of the present invention; 
         FIG. 36  is a cross-sectional view through B-B of  FIG. 34 ; 
         FIG. 37  is a cross-sectional view through C-C of  FIG. 35 ; 
         FIG. 38  is an exploded perspective view of the connector of an airway device according to the fourth embodiment of the present invention; 
         FIG. 39  is a cross-sectional view of the upper airway of a dog; 
         FIGS. 40 and 41  are perspective views of the upper airway of a dog; 
         FIGS. 42 and 43  are perspective views of the trachea and larynx of a dog; and 
         FIGS. 44 to 46  are views illustrating the insertion of an airway device wherein the airway device is shown in cross section, and wherein the anatomical features of the patient are not shown in cross section; 
         FIGS. 47 to 49  illustrate dorsocranial views of the tongue, pharynx, larynx and oesophagus of a dog; 
         FIG. 50  illustrates an anterior view of an exemplary body of a larynx; 
         FIG. 51  illustrates a posterior view of an exemplary body of a larynx; 
         FIG. 52  illustrates a posterior view the cartilages of an exemplary body of a larynx; 
         FIG. 53  is a top (dorsal) view of an airway device according to a fourth embodiment of the present invention; 
         FIG. 54  is a bottom (ventral) view of an airway device according to a fifth embodiment of the present invention; 
         FIG. 55  is a side view of an airway device according to a fifth embodiment of the present invention; 
         FIG. 56  is a cross-sectional view is a cross-sectional view through B-B of  FIG. 54 ; 
         FIG. 57  is a top (dorsal) perspective view of an airway device according to a fifth embodiment of the present invention; 
         FIG. 58  is a bottom (ventral) perspective view of an airway device according to a fifth embodiment of the present invention; 
         FIG. 59  is a cross-sectional view through A-A of  FIG. 54 ; and 
         FIG. 59 a    is a cross-sectional view through A-A of  FIG. 54  illustrating the position of the thickness of the back dorsal portion of the peri-pharyngeal bowl (a) the thickness of the side wall (b), the thickness of the resiliently deformable flange (c) and the footprint of the circumferential lip and resiliently deformable flange (d). 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 5  illustrate a first embodiment of an airway device  10  according to the present invention. The airway device  10  has an airway tube  12  with a distal end  14  and a proximal end  16 . The distal end  14  of the airway tube  12  is provided with a peri-pharyngeal bowl  18 . The peri-pharyngeal bowl is pre-formed in shape and is non-inflatable. The peri-pharyngeal bowl  18  has a posterior bowl portion  19  having a back dorsal portion  20  and a side wall  34  extending around and depending from the periphery of the back dorsal portion  20  which creates an internal space  30   a.  The peri-pharyngeal bowl  18  also has a resiliently deformable flange  35  which extends laterally from the side wall  34  of the back dorsal portion  20  which creates an extended internal space  30   b.  The resiliently deformable flange  35  has an inner and an outer surface that extend to a circumferential edge  22  which may be provided with a circumferential lip (not shown in this embodiment). The peri-pharyngeal bowl  18  is generally ovoid in shape. 
     The proximal end  16  of the airway tube  12  is fitted with a connector  24  such that the proximal end  16  of the airway tube  12  can be connected to the relevant gas supply. 
     The airway device  10  also optionally has a shoulder  26 . The shoulder  26  is used to prevent over-insertion of the airway device  10 , and to provide a visual confirmation of insertion depth. The shoulder  26  if present is located laterally or perpendicular to the direction of the airflow, and thus the airway tube  12 . The shoulder  26  is used to create a point of contact between the airway device  10  and the faucial pillars located at the back of the mouth of a human or animal patient. This creates a positive stopping feature that in use prevents the shoulder  26  going forward beyond the faucial pillars of the patient to prevent over-insertion of the airway device  10 . 
     The internal volume and depth of the peri-pharyngeal bowl  18 , i.e. combination of the internal space  30   a  and extended internal space  30   b  together referred to as the combined internal space  30 , has been increased compared to that found in the laryngeal cuffs of prior art devices. Previously it was thought that the best way to prevent the epiglottis from occluding the airway was to provide a location external to the laryngeal cuff upon which the epiglottis could rest. This may have been through the use of something extending above and across the opening of the airway in the form of an epiglottic rest for example. It has now been discovered, in particular in devices for use particularly in small animals and paediatric humans, that contrary to the teaching of prior art devices, it is better instead to provide a peri-pharyngeal bowl  18  with a large combined internal space  30 , which is configured to contain the body of the larynx of the patient. The combined internal space  30  is configured to not only contain the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained therein that there is still sufficient space in the combined internal space  30  for gases to freely flow to and from the patient without being impeded by the body of the larynx. Preferably the combined internal space  30  contains 50% to 100% of the body of the larynx of the human or animal patient, and more typically 70% to 90% of the body of the larynx of the human or animal patient. In addition, the combined internal space  30  is also configured to contain the body of the larynx of the patient, the body of the larynx should be able to be contained within the combined internal space  30  without any contact being made with any part of the peri-pharyngeal bowl  18  once the airway device  10  is in situ, in particular no contact should be made with the circumferential edge  22 , resiliently deformable flange  35  or side wall  34  of the posterior bowl portion of peri-pharyngeal bowl  18 . Preferably in this case the whole of the body of the larynx is contained within the combined internal space  30 . 
     In order to achieve a sufficiently large enough combined internal space  30  to accomplish the above, not only has the depth of the peri-pharyngeal bowl been increased, but the sides of the peri-pharyngeal bowl  18  in the form of the resiliently deformable flange  35  extending from the side wall  34  posterior bowl portion  19  has also been reduced in thickness compared to the teaching of prior art laryngeal cuff devices, which taught that thick padded walls were required in order to provide the required sealing levels. Ideally the thickness of the resiliently deformable flange  35  is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point. 
     In addition to creating a large combined internal space  30 , the fact that the resiliently deformable flange  35  is much thinner means that it is more flexible and can be readily deformed when required. In particular, the fact that the peri-pharyngeal bowl  18  is readily deformable means that the peri-pharyngeal bowl  18  can be made larger overall than other pre-formed non-inflatable laryngeal cuff prior art devices as the peri-pharyngeal bowl  18  can be readily deformed to pass through structures, such as the faucial pillars, which in the past have led to a reduced size laryngeal cuff in prior art devices. As the peri-pharyngeal bowl  18  comes into contact with the faucial pillars, the resiliently deformable flange  35  deforms inwards allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl  18  has passed beyond the faucial pillars, the resiliently deformable flange  35 , and thus the peri-pharyngeal bowl  18  regain their original shapes. As the dimensions of the peri-pharyngeal bowl  18  are larger than seen in non-inflatable laryngeal cuff prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV especially in larger human or animal patients. The seal that is created is an impaction seal. 
     When pressure is applied to the peri-pharyngeal bowl  18  either from the direction of the back dorsal portion  20  or the circumferential edge  22  of resiliently deformable flange  35 , the force is directed through the peri-pharyngeal bowl  18  to the resiliently deformable flange  35 , wherein the resiliently deformable flange  35  is configured to bend with the force in order to create a seal between the circumferential edge  22  thereof and the peri-larynx, i.e. the area around the larynx and not the larynx itself as was the case in prior art devices. Given that the circumferential edge  22  of the resiliently deformable flange  35  has a small contact area to form a seal in comparison to the prior art pad style airway devices, less force is required to be applied to the airway device  10  in order for the seal to form. 
     The thickness of the sides of the peri-pharyngeal bowl  18  in general may be uniform, however, in the embodiment illustrated the thickness is configured to vary from the side walls  34  of the posterior bowl portion  19  of the peri-pharyngeal bowl  18  to the circumferential edge  22  of the resiliently deformable flange  35  of the peri-pharyngeal bowl  18 . In the embodiment illustrated the thickness of the sides is greatest in the side walls  34  of the posterior bowl portion  19  of the peri-pharyngeal bowl  18  and gradually reduces as it moves towards the start of the resiliently deformable flange  35  wherein the thickness is then generally uniform up to the circumferential edge  22 . The thickness of the sides may be graduated, or it may be stepped. 
     The peri-pharyngeal bowl  18  is provided with a tip  32  at the distal end of the peri-pharyngeal bowl  18 . The tip  32  of the peri-pharyngeal bowl  18  is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient. In addition, tip  32  is optionally provided with an annular sealing ring  42  for improved sealing of the tip  32  of the peri-pharyngeal bowl  18  in the upper oesophagus region of the patient. The tip  32  is configured in such a way to optimize the secondary seal at the upper oesophagus such that excess ventilation does not pass beyond which could otherwise result in gastric insufflation and distension; which could otherwise lead to reflux of the gastric contents into the peri-laryngeal bowl  18  of the device. 
     The side wall  34  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  18 . The depth of the side wall  34  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the side wall  34  is greatest at the proximal end of the peri-pharyngeal bowl  18  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  18 . In another alternative the depth of the side wall  34  may be substantially uniform around the circumference of the peri-pharyngeal bowl  18 . 
     The resiliently deformable flange  35  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  18 . The depth of the resiliently deformable flange  35  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the resiliently deformable flange  35  is greatest at the proximal end of the peri-pharyngeal bowl  18  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  18 . In another alternative the depth of the resiliently deformable flange  35  may be substantially uniform around the circumference of the peri-pharyngeal bowl  18 . 
     The circumferential edge  22  of the peri-pharyngeal bowl  18  is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that whilst it is able to maintain the seal, the circumferential edge  22  does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. If a circumferential lip is provided it too is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that it does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures 
     The airway device  10  is formed from a single shot of plastics material over moulded around the connector  24 . Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     The connector  24  may be formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector  24  may be formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector  24  may be formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In an alternative the connector  24  may be formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     In addition, as illustrated in  FIGS. 6 to 9  the connector  24  is optionally provided with loops or rings  80  which when over moulded prevents the removal of the connector  24  from the airway tube  12  of the airway device  10  without also destroying the airway tube  12  of the airway device  10 . In an alternative not illustrated the connector  24  is optionally provided with a tube within a tube arrangement wherein the inner tube corresponds to the diameter of the airway tube  12  and the outer tube corresponds with the diameter required to connect to the to the relevant gas supply wherein one or more spigots are provided to connect the inner tube to the outer tube. In this arrangement when the connector  24  is over moulded the plastics material fills the void between the inner and outer tubes and over and around the one of more spigots which prevents the removal of the connector  24  from the airway tube  12  of the airway device  10  without also destroying the airway tube  12  of the airway device  10 . In one alternative the connector is a reduced or low dead space connector. 
     The airway device  10  is optionally also further provided with a plurality of ribs (not shown) near the proximal end  16  of the airway tube  12  near to the connector  24 . The ribs provide a friction point for tying the device around an animal&#39;s head as it is generally not possible to use tape as in humans due to the animal&#39;s fur. 
       FIGS. 10 to 14  illustrate a second embodiment of an airway device  110  according to the present invention. The airway device  110  has an airway tube  112  with a distal end  114  and a proximal end  116 . The distal end  114  of the airway tube  112  is provided with a peri-pharyngeal bowl  118 . The peri-pharyngeal bowl is pre-formed in shape and is non-inflatable. The peri-pharyngeal bowl  118  has a posterior bowl portion  119  having a back dorsal portion  120  and a side wall  134  extending around and depending from the periphery of the back dorsal portion  120  which creates an internal space  130   a.  The peri-pharyngeal bowl  118  also has a resiliently deformable flange  135  which extends laterally from the side wall  134  of the back dorsal portion  120  which creates an extended internal space  130   b.  The resiliently deformable flange  135  has an inner and an outer surface that extend to a circumferential edge  122  which may be provided with a circumferential lip  127 . The peri-pharyngeal bowl  18  is generally ovoid in shape. 
     In the embodiment illustrated the circumferential lip  127  is formed by providing the circumferential edge  122  with a bend towards to the outer surface of the circumferential edge  122 , preferably the bend is 70° to 90°. Alternatively, the circumferential lip  127  may be a separate component connected to the outer surface of the circumferential edge  122 . 
     The proximal end  116  of the airway tube  112  is fitted with a connector  124  such that the proximal end  116  of the airway tube  112  can be connected to the relevant gas supply. 
     The airway device  110  also optionally has a shoulder  126 . The shoulder  126  is used to prevent over-insertion of the airway device  110 , and to provide a visual confirmation of insertion depth. The shoulder  26  is located laterally or perpendicular to the direction of the airflow, and thus the airway tube  112 . The shoulder  126  is used to create a point of contact between the airway device  110  and the faucial pillars located at the back of the mouth of a human or animal patient. This creates a positive stopping feature that in use prevents the shoulder  126  going forward beyond the faucial pillars of the patient to prevent over-insertion of the airway device  110 . 
     The internal volume and depth of the peri-pharyngeal bowl  118 , i.e. combination of the internal space  130   a  and extended internal space  130   b  together referred to as the combined internal space  130 , has been increased compared to that found in the laryngeal cuffs of prior art devices. Previously it was thought that the best way to prevent the epiglottis from occluding the airway was to provide a location external to the laryngeal cuff upon which the epiglottis could rest. This may have been through the use of something extending above and across the opening of the airway in the form of an epiglottic rest for example. It has now been discovered, in particular in devices for use particularly in small animals and paediatric humans, that contrary to the teaching of prior art devices, it is better instead to provide a peri-pharyngeal bowl  118  with a large combined internal space  130 , which is configured to contain the body of the larynx of the patient. The combined internal space  130  is configured to not only contain the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained therein that there is still sufficient space in the combined internal space  130  for gases to freely flow to and from the patient without being impeded by the body of the larynx. Preferably the combined internal space  130  contains 50% to 100% of the body of the larynx of the human or animal patient, and more typically 70% to 90% of the body of the larynx of the human or animal patient. In addition, the combined internal space  130  is also configured to contain the body of the larynx of the patient, the body of the larynx should be able to be contained within the combined internal space  130  without any contact being made with any part of the peri-pharyngeal bowl  118  once the airway device  110  is in situ, in particular no contact should be made with the circumferential edge  122 , resiliently deformable flange  135  or side wall  134  of the posterior bowl portion  119  of peri-pharyngeal bowl  118 . Preferably in this case the whole of the body of the larynx is contained within the combined internal space  130 . 
     In order to achieve a sufficiently large enough combined internal space  130  to accomplish the above, not only has the depth of the peri-pharyngeal bowl been increased, but the sides of the peri-pharyngeal bowl  118  in the form of the resiliently deformable flange  135  extending from the side wall  134  posterior bowl portion  119  has also been reduced in thickness compared to the teaching of prior art laryngeal cuff devices, which taught that thick padded walls were required in order to provide the required sealing levels. Ideally the thickness of the resiliently deformable flange  135  is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point 
     In addition to creating a large combined internal space  130 , the fact that the resiliently deformable flange  135  is much thinner means that it is more flexible and can be readily deformed when required. In particular, the fact that the peri-pharyngeal bowl  118  is readily deformable means that the peri-pharyngeal bowl  118  can be made larger overall than other pre-formed non-inflatable laryngeal cuff prior art devices as the peri-pharyngeal bowl  118  can be readily deformed to pass through structures, such as the faucial pillars, which in the past have led to a reduced size laryngeal cuff in prior art devices. As the peri-pharyngeal bowl  118  comes into contact with the faucial pillars, the resiliently deformable flange  135  deforms inwards allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl  118  has passed beyond the faucial pillars, the resiliently deformable flange  135 , and thus the peri-pharyngeal bowl  118  regain their original shapes. As the dimensions of the peri-pharyngeal bowl  118  are larger than seen in non-inflatable laryngeal cuff prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV especially in larger human or animal patients. The seal that is created is an impaction seal. 
     When pressure is applied to the peri-pharyngeal bowl  118  either from the direction of the back dorsal portion  120  or the circumferential edge  122  of resiliently deformable flange  135 , the force is directed through the peri-pharyngeal bowl  118  to the resiliently deformable flange  135 , wherein the resiliently deformable flange  135  is configured to bend with the force in order to create a seal between the circumferential edge  122  thereof and the peri-larynx, i.e. the area around the larynx and not the larynx itself as was the case in prior art devices. Given that the circumferential edge  122  of the resiliently deformable flange  135  has a small contact area to form a seal in comparison to the prior art pad style airway devices, less force is required to be applied to the airway device  110  in order for the seal to form. 
     The thickness of the sides of the peri-pharyngeal bowl  118  in general may be uniform, however, in the embodiment illustrated the thickness is configured to vary from the side walls  134  of the posterior bowl portion  119  of the peri-pharyngeal bowl  118  to the circumferential edge  122  of the resiliently deformable flange  135  of the peri-pharyngeal bowl  118 . In the embodiment illustrated the thickness of the sides is greatest in the side walls  134  of the posterior bowl portion  119  of the peri-pharyngeal bowl  118  and gradually reduces as it moves towards the start of the resiliently deformable flange  135  wherein the thickness is then generally uniform up to the circumferential edge  122 . The thickness of the sides may be graduated, or it may be stepped. 
     The side wall  134  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  118 . The depth of the side wall  134  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the side wall  134  is greatest at the proximal end of the peri-pharyngeal bowl  18  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  118 . In another alternative the depth of the side wall  134  may be substantially uniform around the circumference of the peri-pharyngeal bowl  118 . 
     The peri-pharyngeal bowl  18  is provided with a tip  132  at the distal end of the peri-pharyngeal bowl  118 . The tip  132  of the peri-pharyngeal bowl  118  is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient. In addition, tip  132  is optionally provided with one or more annular sealing rings  142  for improved sealing of the tip  132  of the peri-pharyngeal bowl  118  in the upper oesophagus region of the patient. The tip  132  is configured in such a way to optimize the secondary seal at the upper oesophagus such that excess ventilation does not pass beyond which could otherwise result in gastric insufflation and distension; which could otherwise lead to reflux of the gastric contents into the peri-laryngeal bowl  118  of the device. 
     The resiliently deformable flange  135  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  118 . The depth of the resiliently deformable flange  135  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the resiliently deformable flange  135  is greatest at the proximal end of the peri-pharyngeal bowl  118  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  118 . In another alternative the depth of the resiliently deformable flange  135  may be substantially uniform around the circumference of the peri-pharyngeal bowl  118 . 
     The circumferential edge  122  of the peri-pharyngeal bowl  118  is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that whilst it is able to maintain the seal, the circumferential edge  122  does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. If a circumferential lip is provided it too is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that it does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. 
     The airway device  110  is formed from a single shot of plastics material over moulded around the connector  124 . Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     The connector  124  may be formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector  124  may be formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector  214  may be formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In an alternative the connector  124  may be formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     In addition, as illustrated in  FIGS. 15 to 18  the connector  124  is provided with a tube within a tube arrangement wherein the inner tube  190  corresponds to the diameter of the airway tube  112  and the outer tube  192  corresponds with the diameter required to connect to the to the relevant gas supply wherein one or more spigots  194  are provided to connect the inner tube  190  to the outer tube  192 . In this arrangement when the connector  124  is over moulded the plastics material fills the void between the inner and outer tubes  190 ,  192  and over and around the one of more spigots  194  which prevents the removal of the connector  124  from the airway tube  112  of the airway device  110  without also destroying the airway tube  112  of the airway device  110 . In an alternative loops or rings may be provided on the external surface of the connector as illustrated in respect of the first embodiment of the invention which when over moulded prevents the removal of the connector  124  from the airway tube  112  of the airway device  110  without also destroying the airway tube  112  of the airway device  110 . In one alternative the connector is a reduced or low dead space connector. 
     The airway device  110  is optionally also further provided with a plurality of ribs (not shown) near the proximal end  116  of the airway tube  112  near to the connector  124 . The ribs provide a friction point for tying the device around an animal&#39;s head as it is generally not possible to use tape as in humans due to the animal&#39;s fur. 
       FIGS. 19 to 23  illustrate a third embodiment of an airway device  210  according to the present invention. The airway device  210  has an airway tube  212  with a distal end  214  and a proximal end  216 . The distal end  214  of the airway tube  212  is provided with a peri-pharyngeal bowl  218 . The peri-pharyngeal bowl is pre-formed in shape and is non-inflatable. The peri-pharyngeal bowl  218  has a posterior bowl portion  219  having a back dorsal portion  220  and a side wall  234  extending around and depending from the periphery of the back dorsal portion  220  which creates an internal space  230   a.  The peri-pharyngeal bowl  218  also has a resiliently deformable flange  235  which extends laterally from the side wall  234  of the back dorsal portion  220  which creates an extended internal space  230   b.  The resiliently deformable flange  235  has an inner and an outer surface that extend to a circumferential edge  222  which may be provided with a circumferential lip  227 . The peri-pharyngeal bowl  218  is generally ovoid in shape. 
     In the embodiment illustrated the circumferential lip  227  is formed by providing the circumferential edge  222  with a bend towards to the both the outer and inner surfaces of the circumferential edge  222 , preferably the bend is 70° to 90°. Alternatively, the circumferential lip  227  may be a separate component connected to the outer surface of the circumferential edge  222 . 
     The proximal end  216  of the airway tube  212  is fitted with a connector  224  such that the proximal end  216  of the airway tube  212  can be connected to the relevant gas supply. 
     The airway device  210  also optionally has a shoulder  226 . The shoulder  226  is used to prevent over-insertion of the airway device  210 , and to provide a visual confirmation of insertion depth. The shoulder  226  if present is located laterally or perpendicular to the direction of the airflow, and thus the airway tube  212 . The shoulder  226  is used to create a point of contact between the airway device  210  and the faucial pillars located at the back of the mouth of a human or animal patient. This creates a positive stopping feature that in use prevents the shoulder  226  going forward beyond the faucial pillars of the patient to prevent over-insertion of the airway device  210 . 
     The internal volume and depth of the peri-pharyngeal bowl  218 , i.e. combination of the internal space  230   a  and extended internal space  230   b  together referred to as the combined internal space  230 , has been increased compared to that found in the laryngeal cuffs of prior art devices. Previously it was thought that the best way to prevent the epiglottis from occluding the airway was to provide a location external to the laryngeal cuff upon which the epiglottis could rest. This may have been through the use of something extending above and across the opening of the airway in the form of an epiglottic rest for example. It has now been discovered, in particular in devices for use particularly in small animals and paediatric humans, that contrary to the teaching of prior art devices, it is better instead to provide a peri-pharyngeal bowl  218  with a large combined internal space  230 , which is configured to contain the body of the larynx of the patient. The combined internal space  230  is configured to not only contain the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained therein that there is still sufficient space in the combined internal space  230  for gases to freely flow to and from the patient without being impeded by the body of the larynx. Preferably the combined internal space  230  contains 50% to 100% of the body of the larynx of the human or animal patient, and more typically 70% to 90% of the body of the larynx of the human or animal patient. In addition, the combined internal space  230  is also configured to contain the body of the larynx of the patient, the body of the larynx should be able to be contained within the combined internal space  230  without any contact being made with any part of the peri-pharyngeal bowl  218  once the airway device  210  is in situ, in particular no contact should be made with the circumferential edge  222 , resiliently deformable flange  235  or side wall  234  of the posterior bowl portion  219  of peri-pharyngeal bowl  218 . Preferably in this case the whole of the body of the larynx is contained within the combined internal space  230 . 
     In order to achieve a sufficiently large enough combined internal space  230  to accomplish the above, not only has the depth of the peri-pharyngeal bowl been increased, but the sides of the peri-pharyngeal bowl  218  in the form of the resiliently deformable flange  235  extending from the side wall  234  posterior bowl portion  219  has also been reduced in thickness compared to the teaching of prior art laryngeal cuff devices, which taught that thick padded walls were required in order to provide the required sealing levels. Ideally the thickness of the resiliently deformable flange  235  is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point 
     In addition to creating a large combined internal space  230 , the fact that the resiliently deformable flange  235  is much thinner means that it is more flexible and can be readily deformed when required. In particular, the fact that the peri-pharyngeal bowl  218  is readily deformable means that the peri-pharyngeal bowl  218  can be made larger overall than other pre-formed non-inflatable laryngeal cuff prior art devices as the peri-pharyngeal bowl  218  can be readily deformed to pass through structures, such as the faucial pillars, which in the past have led to a reduced size laryngeal cuff in prior art devices. As the peri-pharyngeal bowl  218  comes into contact with the faucial pillars, the resiliently deformable flange  235  deforms inwards allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl  218  has passed beyond the faucial pillars, the resiliently deformable flange  235 , and thus the peri-pharyngeal bowl  218  regain their original shapes. As the dimensions of the peri-pharyngeal bowl  218  are larger than seen in non-inflatable laryngeal cuff prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV especially in larger human or animal patients. The seal that is created is an impaction seal. 
     When pressure is applied to the peri-pharyngeal bowl  218  either from the direction of the back dorsal portion  220  or the circumferential edge  222  of resiliently deformable flange  235 , the force is directed through the peri-pharyngeal bowl  218  to the resiliently deformable flange  235 , wherein the resiliently deformable flange  235  is configured to bend with the force in order to create a seal between the circumferential edge  222  thereof and the peri-larynx, i.e. the area around the larynx and not the larynx itself as was the case in prior art devices. Given that the circumferential edge  222  of the resiliently deformable flange  235  has a small contact area to form a seal in comparison to the prior art pad style airway devices, less force is required to be applied to the airway device  210  in order for the seal to form. 
     The thickness of the sides of the peri-pharyngeal bowl  218  in general may be uniform, however, in the embodiment illustrated the thickness is configured to vary from the side walls  234  of the posterior bowl portion  219  of the peri-pharyngeal bowl  218  to the circumferential edge  222  of the resiliently deformable flange  235  of the peri-pharyngeal bowl  218 . In the embodiment illustrated the thickness of the sides is greatest in the side walls  234  of the posterior bowl portion  219  of the peri-pharyngeal bowl  218  and gradually reduces as it moves towards the start of the resiliently deformable flange  235  wherein the thickness is then generally uniform up to the circumferential edge  222 . The thickness of the sides may be graduated, or it may be stepped. 
     The side wall  234  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  218 . The depth of the side wall  234  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the side wall  234  is greatest at the proximal end of the peri-pharyngeal bowl  218  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  218 . In another alternative the depth of the side wall  234  may be substantially uniform around the circumference of the peri-pharyngeal bowl  218 . 
     The peri-pharyngeal bowl  218  is provided with a tip  232  at the distal end of the peri-pharyngeal bowl  218 . The tip  232  of the peri-pharyngeal bowl  218  is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient. In addition, tip  232  is optionally provided with one or more annular sealing rings  242  for improved sealing of the tip  232  of the peri-pharyngeal bowl  218  in the upper oesophagus region of the patient. The tip  232  is configured in such a way to optimize the secondary seal at the upper oesophagus such that excess ventilation does not pass beyond which could otherwise result in gastric insufflation and distension; which could otherwise lead to reflux of the gastric contents into the peri-laryngeal bowl  218  of the device. 
     The resiliently deformable flange  235  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  218 . The depth of the resiliently deformable flange  235  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative as in the embodiment illustrated the depth of the resiliently deformable flange  235  is greatest at the proximal end of the peri-pharyngeal bowl  218  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  218 . In another alternative the depth of the resiliently deformable flange  235  may be substantially uniform around the circumference of the peri-pharyngeal bowl  218 . 
     The circumferential edge  222  of the peri-pharyngeal bowl  218  is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that whilst it is able to maintain the seal, the circumferential edge  222  does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. The circumferential lip  227  is also preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that it does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures 
     The airway device  210  is formed from a single shot of plastics material over moulded around the connector  224 . Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     The connector  224  may be formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector  224  may be formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector  224  may be formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In an alternative the connector  224  may be formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     In addition, as illustrated in  FIGS. 24 to 27  the connector  224  is provided with a tube within a tube arrangement wherein the inner tube  290  corresponds to the diameter of the airway tube  212  and the outer tube  292  corresponds with the diameter required to connect to the to the relevant gas supply wherein one or more spigots  294  are provided to connect the inner tube  290  to the outer tube  292 . In this arrangement when the connector  224  is over moulded the plastics material fills the void between the inner and outer tubes  290 ,  292  and over and around the one of more spigots  294  which prevents the removal of the connector  224  from the airway tube  212  of the airway device  210  without also destroying the airway tube  212  of the airway device  210 . In an alternative loops or rings may be provided on the external surface of the connector as illustrated in respect of the first embodiment of the invention which when over moulded prevents the removal of the connector  224  from the airway tube  212  of the airway device  210  without also destroying the airway tube  212  of the airway device  210 . In one alternative the connector is a reduced or low dead space connector. 
     The airway device  210  is optionally also further provided with a plurality of ribs (not shown) near the proximal end  216  of the airway tube  212  near to the connector  224 . The ribs provide a friction point for tying the device around an animal&#39;s head as it is generally not possible to use tape as in humans due to the animal&#39;s fur. 
       FIGS. 29 to 33  illustrate a fourth embodiment of an airway device  310  according to the present invention. The airway device  310  has an airway tube  312  with a distal end  314  and a proximal end  316 . The distal end  314  of the airway tube  312  is provided with a peri-pharyngeal bowl  318 . The peri-pharyngeal bowl is pre-formed in shape and is non-inflatable. The peri-pharyngeal bowl  318  has a posterior bowl portion  319  having a back dorsal portion  320  and a side wall  334  extending around and depending from the periphery of the back dorsal portion  320  which creates an internal space  330   a.  The peri-pharyngeal bowl  318  also has a resiliently deformable flange  335  which extends laterally from the side wall  334  of the back dorsal portion  320  which creates an extended internal space  330   b.  The resiliently deformable flange  335  has an inner and an outer surface that extend to a circumferential edge  322  which may be provided with a circumferential lip  327 . The peri-pharyngeal bowl  318  is generally ovoid in shape. 
     In the embodiment illustrated the circumferential lip  327  is formed by providing the circumferential edge  322  with a bend towards to the outer surface of the circumferential edge  322 , preferably the bend is 70° to 90°. Alternatively, the circumferential lip  327  may be a separate component connected to the outer surface of the circumferential edge  322 . 
     The proximal end  316  of the airway tube  312  is fitted with a connector  324  such that the proximal end  316  of the airway tube  312  can be connected to the relevant gas supply. 
     The airway device  310  also optionally has a shoulder  326 . The shoulder  326  is used to prevent over-insertion of the airway device  310 , and to provide a visual confirmation of insertion depth. The shoulder  326  if present is located laterally or perpendicular to the direction of the airflow, and thus the airway tube  312 . The shoulder  326  is used to create a point of contact between the airway device  310  and the faucial pillars located at the back of the mouth of a human or animal patient. This creates a positive stopping feature that in use prevents the shoulder  326  going forward beyond the faucial pillars of the patient to prevent over-insertion of the airway device  310 . 
     The internal volume and depth of the peri-pharyngeal bowl  318 , i.e. combination of the internal space  330   a  and extended internal space  330   b  together referred to as the combined internal space  330 , has been increased compared to that found in the laryngeal cuffs of prior art devices. Previously it was thought that the best way to prevent the epiglottis from occluding the airway was to provide a location external to the laryngeal cuff upon which the epiglottis could rest. This may have been through the use of something extending above and across the opening of the airway in the form of an epiglottic rest for example. It has now been discovered, in particular in devices for use particularly in small animals and paediatric humans, that contrary to the teaching of prior art devices, it is better instead to provide a peri-pharyngeal bowl  318  with a large combined internal space  330 , which is configured to contain the body of the larynx of the patient. The combined internal space  330  is configured to not only contain the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained therein that there is still sufficient space in the combined internal space  330  for gases to freely flow to and from the patient without being impeded by the body of the larynx. Preferably the combined internal space  330  contains 50% to 100% of the body of the larynx of the human or animal patient, and more typically 70% to 90% of the body of the larynx of the human or animal patient. In addition, the combined internal space  330  is also configured to contain the body of the larynx of the patient, the body of the larynx should be able to be contained within the combined internal space  330  without any contact being made with any part of the peri-pharyngeal bowl  318  once the airway device  310  is in situ, in particular no contact should be made with the circumferential edge  322 , resiliently deformable flange  335  or side wall  334  of the posterior bowl portion  319  of peri-pharyngeal bowl  318 . Preferably in this case the whole of the body of the larynx is contained within the combined internal space  330 . 
     In order to achieve a sufficiently large enough combined internal space  330  to accomplish the above, not only has the depth of the peri-pharyngeal bowl been increased, but the sides of the peri-pharyngeal bowl  318  in the form of the resiliently deformable flange  335  extending from the side wall  334  posterior bowl portion  319  has also been reduced in thickness compared to the teaching of prior art laryngeal cuff devices, which taught that thick padded walls were required in order to provide the required sealing levels. Ideally the thickness of the resiliently deformable flange  335  is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point 
     In addition to creating a large combined internal space  330 , the fact that the resiliently deformable flange  335  is much thinner means that it is more flexible and can be readily deformed when required. In particular, the fact that the peri-pharyngeal bowl  318  is readily deformable means that the peri-pharyngeal bowl  318  can be made larger overall than other pre-formed non-inflatable laryngeal cuff prior art devices as the peri-pharyngeal bowl  318  can be readily deformed to pass through structures, such as the faucial pillars, which in the past have led to a reduced size laryngeal cuff in prior art devices. As the peri-pharyngeal bowl  318  comes into contact with the faucial pillars, the resiliently deformable flange  335  deforms inwards allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl  318  has passed beyond the faucial pillars, the resiliently deformable flange  335 , and thus the peri-pharyngeal bowl  318  regain their original shapes. As the dimensions of the peri-pharyngeal bowl  318  are larger than seen in non-inflatable laryngeal cuff prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV especially in larger human or animal patients. The seal that is created is an impaction seal. 
     When pressure is applied to the peri-pharyngeal bowl  318  either from the direction of the back dorsal portion  320  or the circumferential edge  322  of resiliently deformable flange  335 , the force is directed through the peri-pharyngeal bowl  318  to the resiliently deformable flange  335 , wherein the resiliently deformable flange  335  is configured to bend with the force in order to create a seal between the circumferential edge  322  thereof and the peri-larynx, i.e. the area around the larynx and not the larynx itself as was the case in prior art devices. Given that the circumferential edge  322  of the resiliently deformable flange  335  has a small contact area to form a seal in comparison to the prior art pad style airway devices, less force is required to be applied to the airway device  310  in order for the seal to form. 
     The thickness of the sides of the peri-pharyngeal bowl  318  in general may be uniform, however, in the embodiment illustrated the thickness is configured to vary from the side walls  334  of the posterior bowl portion  319  of the peri-pharyngeal bowl  318  to the circumferential edge  322  of the resiliently deformable flange  335  of the peri-pharyngeal bowl  318 . In the embodiment illustrated the thickness of the sides is greatest in the side walls  334  of the posterior bowl portion  319  of the peri-pharyngeal bowl  318  and gradually reduces as it moves towards the start of the resiliently deformable flange  335  wherein the thickness is then generally uniform up to the circumferential edge  322 . The thickness of the sides may be graduated, or it may be stepped. 
     The side wall  334  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  318 . The depth of the side wall  334  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative the depth of the side wall  334  is greatest at the proximal end of the peri-pharyngeal bowl  318  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  318 . In another alternative the depth of the side wall  334  may be substantially uniform around the circumference of the peri-pharyngeal bowl  318 . 
     The peri-pharyngeal bowl  318  is provided with a tip  332  at the distal end of the peri-pharyngeal bowl  318 . The tip  332  of the peri-pharyngeal bowl  318  is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient. In addition, tip  332  is optionally provided with one or more annular sealing rings (not shown) for improved sealing of the tip  332  of the peri-pharyngeal bowl  318  in the upper oesophagus region of the patient. The tip  332  is configured in such a way to optimize the secondary seal at the upper oesophagus such that excess ventilation does not pass beyond which could otherwise result in gastric insufflation and distension; which could otherwise lead to reflux of the gastric contents into the peri-laryngeal bowl  318  of the device. 
     The resiliently deformable flange  335  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  318 . The depth of the resiliently deformable flange  335  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative as in the embodiment illustrated the depth of the resiliently deformable flange  335  is greatest at the proximal end of the peri-pharyngeal bowl  318  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  318 . In another alternative the depth of the resiliently deformable flange  335  may be substantially uniform around the circumference of the peri-pharyngeal bowl  318 . 
     The circumferential edge  322  of the peri-pharyngeal bowl  318  is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that whilst it is able to maintain the seal, the circumferential edge  322  does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. The circumferential lip  327  is also preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that it does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures 
     The airway device  310  is formed from a single shot of plastics material over moulded around the connector  324 . Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     The connector  324  may be formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector  324  may be formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector  324  may be formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In an alternative the connector  324  may be formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     In addition, as illustrated in  FIGS. 34 to 38  the connector  324  is optionally provided with loops or rings  380  which when over moulded prevents the removal of the connector from the airway tube of the device without also destroying the airway tube of the device. In an alternative not illustrated the connector  324  is optionally provided with a tube within a tube arrangement wherein the inner tube corresponds to the diameter of the airway tube  312  and the outer tube corresponds with the diameter required to connect to the to the relevant gas supply wherein one or more spigots are provided to connect the inner tube to the outer tube. In this arrangement when the connector  324  is over moulded the plastics material fills the void between the inner and outer tubes and over and around the one of more spigots which prevents the removal of the connector  324  from the airway tube  312  of the airway device  310  without also destroying the airway tube  312  of the airway device  310 . In one alternative the connector is a reduced or low dead space connector. 
     The airway device  310  is optionally also further provided with a plurality of ribs  360  near the proximal end  316  of the airway tube  312  near to the connector  324 . The ribs  360  provide a friction point for tying the airway device  310  around an animal&#39;s head as it is generally not possible to use tape as in humans due to the animal&#39;s fur. 
     The back dorsal portion  320  of the posterior bowl portion  319  or the peri-pharyngeal bowl  218  is optionally flattened with gently squared corners  323 . This squared rather than curved feature prevents the peri-pharyngeal bowl  318  from rocking when in situ in the human or animal patient and therefore gives greater stability to the airway device  310  when it is in situ in the human or animal patient. 
     The airway device  310  is optionally provided with an oesophageal gastric channel  382  extending along the length of the device exiting through tip  332  of peri-pharyngeal bowl  318 . In typical prior art devices, the gastric channel entry point at the distal end of the device is a round hole. The clinician would then feed a gastric tube or the like into this hole for it to then pass down the channel into the stomach of the patient in order to decompress the stomach of gastric fluids and gases. It can sometimes be challenging to get the small round gastric tube into the small round opening of the gastric channel, as the gastric tube is itself flexible and will bend if not inserted exactly. In the present invention in order to overcome this problem, the distal end of the gastric channel is provided with a graduated oval entry point  384  rather than a circular entry point, as if the distal end of the channel had been cut at an angle. This gives a greater sized opening and a ramp to guide the gastric tube down into the gastric channel  382 . 
     In this embodiment the airway tube  312  is oval rather than cylindrical, however, the connection to the breathing machine is cylindrical. Therefore, an adaptor  370  is provided to “reduce” the diameter of airway tube  312  at its proximal end  314  from the oval shape to a circle into which a standard 15 mm connector can be fitted. The proximal end  316  of the airway tube is then fitted with a standard 15 mm connector such that the proximal end  316  of the airway tube  312  can be connected to the relevant gas supply. 
       FIGS. 39 to 43  are provided to illustrate and provide understanding of the anatomy of the upper airway of a dog and in particular the functioning of the epiglottis. 
       FIG. 39  illustrates the cross-sectional view of the upper airway of a dog. The larynx, trachea and epiglottis form one complete structure. It can be seen that the soft palate is sitting against the epiglottis, which would be the normal position if the dog were breathing through its nose. When a dog is panting, this means that it is breathing through both its mouth and its nose, in this scenario the soft palate would move away from the epiglottis to open up the larynx for air flow by both channels. 
       FIGS. 40 and 41  illustrate perspective views of the upper airway of a dog.  FIG. 40  illustrates the upper airway when the epiglottis is in the open position for breathing. The epiglottis is in the form of a deep bowl with pronounced lateral sides. When the epiglottis is in the open position the larynx can be accessed.  FIG. 41  illustrates the upper airway when the epiglottis is in the closed position for swallowing. The epiglottis moves from the open to the closed position by pivoting about the base thereof. 
       FIGS. 42 and 43  illustrate perspective views of the trachea, larynx and epiglottis assembly.  FIG. 42  illustrates the assembly when the epiglottis is in the open position.  FIG. 43  illustrates the assembly when the epiglottis is in the closed position. Both of these figures illustrate the point about which the epiglottis pivots as it moves between the open and the closed positions. 
     Thus, in all breeds of dog, the bowl of the epiglottis in its natural open breathing position sits so that its open face is upwards against the soft palate. When the dog breaths the bowl of the epiglottis and the soft palate disengage to allow the flow of air through the open face of the bowl of the epiglottis down into the larynx. When the dog swallows while awake the epiglottis pivots to fully cover the larynx. 
       FIGS. 44 to 46  illustrate what happens during the insertion of airway device  310  wherein the airway device is shown in cross section, and wherein the anatomical features of the patient are not shown in cross section. 
       FIGS. 47 and 49  illustrate dorsocranial views of the tongue, pharynx, larynx and oesophagus of a dog. 
       FIGS. 53 to 59  illustrate a fifth embodiment of an airway device  410  according to the present invention. The airway device  410  has an airway tube  412  with a distal end  414  and a proximal end  416 . The distal end  414  of the airway tube  412  is provided with a peri-pharyngeal bowl  418 . The peri-pharyngeal bowl is pre-formed in shape and is non-inflatable. The peri-pharyngeal bowl  418  has a posterior bowl portion  419  having a back dorsal portion  420  and a side wall  434  extending around and depending from the periphery of the back dorsal portion  420  which creates an internal space  430   a.  The peri-pharyngeal bowl  418  also has a resiliently deformable flange  435  which extends laterally from the side wall  434  of the back dorsal portion  420  which creates an extended internal space  430   b.  The resiliently deformable flange  435  has an inner and an outer surface that extend to a circumferential edge  422  which may be provided with a circumferential lip  427 . The peri-pharyngeal bowl  418  is generally ovoid in shape. 
     In the embodiment illustrated the circumferential lip  427  is formed by providing the circumferential edge  422  with a bend towards to the outer surface of the circumferential edge  422 , preferably the bend is 70° to 90°. Alternatively, the circumferential lip  427  may be a separate component connected to the outer surface of the circumferential edge  422 . 
     The proximal end  416  of the airway tube  412  may be fitted with a connector (not shown) such that the proximal end  416  of the airway tube  412  can be connected to the relevant gas supply. 
     The airway device  410  may optionally have a shoulder (not illustrated). The shoulder if present is used to prevent over-insertion of the airway device  410 , and to provide a visual confirmation of insertion depth. The shoulder if present is located laterally or perpendicular to the direction of the airflow, and thus the airway tube  412 . The shoulder if present is used to create a point of contact between the airway device  410  and the faucial pillars located at the back of the mouth of a human or animal patient. This creates a positive stopping feature that in use prevents the shoulder if present going forward beyond the faucial pillars of the patient to prevent over-insertion of the airway device  410 . 
     The internal volume and depth of the peri-pharyngeal bowl  418 , i.e. combination of the internal space  430   a  and extended internal space  330   b  together referred to as the combined internal space  430 , has been increased compared to that found in the laryngeal cuffs of prior art devices. Previously it was thought that the best way to prevent the epiglottis from occluding the airway was to provide a location external to the laryngeal cuff upon which the epiglottis could rest. This may have been through the use of something extending above and across the opening of the airway in the form of an epiglottic rest for example. It has now been discovered, in particular in devices for use particularly in small animals and paediatric humans, that contrary to the teaching of prior art devices, it is better instead to provide a peri-pharyngeal bowl  418  with a large combined internal space  430 , which is configured to contain the body of the larynx of the patient. The combined internal space  430  is configured to not only contain the body of the larynx, but also to be sufficiently sized such that once the body of the larynx has been contained therein that there is still sufficient space in the combined internal space  430  for gases to freely flow to and from the patient without being impeded by the body of the larynx. Preferably the combined internal space  430  contains 50% to 100% of the body of the larynx of the human or animal patient, and more typically 70% to 90% of the body of the larynx of the human or animal patient. In addition, the combined internal space  430  is also configured to contain the body of the larynx of the patient, the body of the larynx should be able to be contained within the combined internal space  430  without any contact being made with any part of the peri-pharyngeal bowl  418  once the airway device  410  is in situ, in particular no contact should be made with the circumferential edge  422 , resiliently deformable flange  435  or side wall  434  of the posterior bowl portion  419  of peri-pharyngeal bowl  418 . Preferably in this case the whole of the body of the larynx is contained within the combined internal space  430 . 
     In order to achieve a sufficiently large enough combined internal space  430  to accomplish the above, not only has the depth of the peri-pharyngeal bowl been increased, but the sides of the peri-pharyngeal bowl  418  in the form of the resiliently deformable flange  435  extending from the side wall  434  posterior bowl portion  419  has also been reduced in thickness compared to the teaching of prior art laryngeal cuff devices, which taught that thick padded walls were required in order to provide the required sealing levels. Ideally the thickness of the resiliently deformable flange  335  is about 1% to 15% of the external width of the peri-pharyngeal bowl at its widest point 
     In addition to creating a large combined internal space  430 , the fact that the resiliently deformable flange  435  is much thinner means that it is more flexible and can be readily deformed when required. In particular, the fact that the peri-pharyngeal bowl  418  is readily deformable means that the peri-pharyngeal bowl  418  can be made larger overall than other pre-formed non-inflatable laryngeal cuff prior art devices as the peri-pharyngeal bowl  418  can be readily deformed to pass through structures, such as the faucial pillars, which in the past have led to a reduced size laryngeal cuff in prior art devices. As the peri-pharyngeal bowl  418  comes into contact with the faucial pillars, the resiliently deformable flange  435  deforms inwards allowing the peri-pharyngeal bowl to pass through and beyond the faucial pillars. After the peri-pharyngeal bowl  318  has passed beyond the faucial pillars, the resiliently deformable flange  335 , and thus the peri-pharyngeal bowl  418  regain their original shapes. As the dimensions of the peri-pharyngeal bowl  418  are larger than seen in non-inflatable laryngeal cuff prior arts devices a more effective seal is created, which allows for higher sealing pressures which are required for IPPV especially in larger human or animal patients. The seal that is created is an impaction seal. 
     When pressure is applied to the peri-pharyngeal bowl  418  either from the direction of the back dorsal portion  420  or the circumferential edge  422  of resiliently deformable flange  435 , the force is directed through the peri-pharyngeal bowl  418  to the resiliently deformable flange  435 , wherein the resiliently deformable flange  435  is configured to bend with the force in order to create a seal between the circumferential edge  422  thereof and the peri-larynx, i.e. the area around the larynx and not the larynx itself as was the case in prior art devices. Given that the circumferential edge  422  of the resiliently deformable flange  435  has a small contact area to form a seal in comparison to the prior art pad style airway devices, less force is required to be applied to the airway device  410  in order for the seal to form. 
     The thickness of the sides of the peri-pharyngeal bowl  418  in general may be uniform, however, in the embodiment illustrated the thickness is configured to vary from the side walls  434  of the posterior bowl portion  419  of the peri-pharyngeal bowl  418  to the circumferential edge  422  of the resiliently deformable flange  435  of the peri-pharyngeal bowl  418 . In the embodiment illustrated the thickness of the sides is greatest in the side walls  434  of the posterior bowl portion  419  of the peri-pharyngeal bowl  418  and gradually reduces as it moves towards the start of the resiliently deformable flange  435  wherein the thickness is then generally uniform up to the circumferential edge  422 . The thickness of the sides may be graduated, or it may be stepped. 
     The peri-pharyngeal bowl  418  is provided with a tip  432  at the distal end of the peri-pharyngeal bowl  418 . The tip  432  of the peri-pharyngeal bowl  418  is configured to wedge anatomically correctly into the upper oesophagus region of the human or animal patient. In addition, tip  432  is optionally provided with one or more annular sealing rings (not shown) for improved sealing of the tip  432  of the peri-pharyngeal bowl  418  in the upper oesophagus region of the patient. The tip  432  is configured in such a way to optimize the secondary seal at the upper oesophagus such that excess ventilation does not pass beyond which could otherwise result in gastric insufflation and distension; which could otherwise lead to reflux of the gastric contents into the peri-laryngeal bowl  418  of the device. 
     The resiliently deformable flange  435  is configured to extend substantially around the entire circumference of the peri-pharyngeal bowl  418 . The depth of the resiliently deformable flange  435  may be configured to vary around the circumference of the peri-pharyngeal bowl. In one alternative as in the embodiment illustrated the depth of the resiliently deformable flange  435  is greatest at the proximal end of the peri-pharyngeal bowl  418  and gradually reduces as it moves towards the distal end of the peri-pharyngeal bowl  418 . In another alternative the depth of the resiliently deformable flange  435  may be substantially uniform around the circumference of the peri-pharyngeal bowl  418 . 
     The circumferential edge  422  of the peri-pharyngeal bowl  418  is preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that whilst it is able to maintain the seal, the circumferential edge  422  does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures. The circumferential lip  427  is also preferably rounded or curved such that is it blunt and does not have any squared edges in such a way that it does not cause excessive mucosal pressures thus avoiding any trauma to the delicate structures 
     The airway device  410  is formed from a single shot of plastics material which may be moulded around a connector if provided. Preferably the plastics material is of 10 to 90 Shore Hardness on the A scale. In the case of a device for guinea pigs for example the device will be formed from a plastics material of typically 20 to 70 Shore Hardness on the A scale. In the case of a device for rabbits for example the device will be formed from a plastics material of typically 35 to 70 Shore Hardness on the A scale. In the case of a device for cats and/or dogs for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for horses for example the device will be formed from a plastics material of typically 20 to 60 Shore Hardness on the A scale. In the case of a device for humans the device will be formed from a plastics material of typically 20 to 50 Shore Hardness on the A scale, preferably less than 50 Shore Hardness on the A scale, preferably less than 40 Shore Hardness on the A scale, preferably 30 to 35 Shore Hardness on the A scale. 
     The connector may be formed from a material which loses its structure and/or rigidity when exposed to water. In one alternative the connector may be formed from a material that swells when exposed to water such as starch or cellulose. In another alternative the connector may be formed from a material that becomes flexible or collapses or dissolves when exposed to water such as polyvinyl alcohol. 
     In an alternative the connector may be formed from a standard plastics material whose structure is not impacted on exposure to water such as polycarbonate, polyurethane, polypropylene or polyvinylchloride. 
     The connector is optionally provided with loops or rings or other member which when over moulded prevents the removal of the connector from the airway tube of the device without also destroying the airway tube of the device. In an alternative the connector is optionally provided with a tube within a tube arrangement wherein the inner tube corresponds to the diameter of the airway tube  412  and the outer tube corresponds with the diameter required to connect to the to the relevant gas supply wherein one or more spigots are provided to connect the inner tube to the outer tube. In this arrangement when the connector is over moulded the plastics material fills the void between the inner and outer tubes and over and around the one of more spigots which prevents the removal of the connector from the airway tube  412  of the airway device  410  without also destroying the airway tube  412  of the airway device  410 . In one alternative the connector is a reduced or low dead space connector. 
     The airway device  410  is optionally also further provided with a plurality of ribs (not shown) near the proximal end  416  of the airway tube  412 . The ribs  360  provide a friction point for tying the airway device  410  around an animal&#39;s head as it is generally not possible to use tape as in humans due to the animal&#39;s fur. 
     The airway device  410  is optionally provided with an oesophageal gastric channel  482  extending along the length of the device exiting through tip  432  of peri-pharyngeal bowl  418 .