Improved laryngeal mask

Abstract

A laryngeal mask comprising a neck comprising a proximal end and a distal end, and extending therebetween, a head extending from the distal end of the neck and comprising a sealing face, a resiliently deformable portion and a cavity disposed between the sealing face and the resiliently deformable portion, and an airway tube extending from a proximal airway tube opening in the proximal end of the neck to a distal airway tube opening in the sealing face of the head. The resiliently deformable portion is moveable into the cavity from a first uncompressed configuration to a second compressed configuration, and in the second compressed configuration the resiliently deformable portion exerts a restoring force in a direction away from the sealing face of 5.8 N or less.

Description

IMPROVED LARYNGEAL MASK

[0001] The present invention relates to an airway device and, in particular, to a laryngeal mask for facilitating the passage of air into and out of a patient.BACKGROUND

[0002] Traditionally, endotracheal tubes have been used to establish an airway in an unconscious patient. Endotracheal tubes comprise an elongate tube having an inflatable cuff, or balloon positioned at the tube’s distal end. In use, the distal end of the endotracheal tube is inserted into the patient’s trachea via the patient’s mouth. Once correctly positioned, the cuff is inflated to form a seal with the interior lining of the trachea, which prevents aspiration of gastric fluid into the patient’s lungs. The proximal end of the tube is connected to a ventilation device for providing positive pressure to ventilate the patient’s lungs.

[0003] However, endotracheal tubes have several disadvantages including being difficult to correctly position within a patient’s airway and requiring significant manipulating of a patient’s head and neck in order to insert the tube, which in some patients, such as those suffering a neck or spinal injury, may be highly undesirable. Furthermore, since the distal end of the endotracheal tube is positioned within the trachea and necessarily passes through the laryngeal structures, it is not uncommon for a patient to suffer from some degree of laryngeal morbidity such as postoperative hoarseness, or dysphagia.

[0004] Laryngeal mask airway devices (hereinafter “laryngeal masks”) were therefore developed with the aim of overcoming the aforementioned disadvantages associated with endotracheal tubes. In contrast to the endotracheal tube, laryngeal masks are relatively easy to insert to establish an airway in a patient, and only require relatively minor manipulation of the patient’s head and neck in order to correctly position the mask. Importantly, and in contrast to endotracheal tubes, the laryngeal mask provides ventilation of a patient’s lungs without contacting the sensitive inner lining of the trachea or laryngeal structures, thus reducing the occurrence of post-operative complications such as those listed above.

[0005] In general terms, known laryngeal masks typically comprise an airway tube opening at one end into the interior of a hollow mask portion. The mask portion is shaped to fit over the larynx of a patient. The periphery of the mask is often formed by a cuff which in use forms a seal around the laryngeal opening, thus establishing an effective airway.

[0006] However, to ensure that a seal is adequately formed, it has been necessary to provide laryngeal masks in a variety of sizes, so as to suit different sizes of patient. For example, the diameter of the airway tube and the proportions of the mask part, respectively, can be varied so as to be suitable for a particular weight range of a patient, e.g. “small adult (30-50 kg), “medium adult” (50-90 kg) and “large adult” (90+ kg), each of whom will have different sizes of laryngeal region.

[0007] Selection of the suitable size of laryngeal mask is typically based on a manufacturer’s recommendation of weight-based estimate, plus clinical judgement. However, it will be appreciated that the natural and potentially unpredictable variations in patient anatomy mean that these selection parameters may not necessarily suit each patient’s needs.

[0008] There therefore exists a need for improved airway devices that mitigate at least some of the disadvantages associated with known laryngeal masks.

[0009] It is an object of certain embodiments of the present invention to overcome one or more disadvantages associated with the prior art.BRIEF SUMMARY

[0010] In accordance with an aspect of the present invention there is provided a laryngeal mask comprising a neck that includes a proximal end and a distal end, and extending therebetween, a head extending from the distal end of the neck and includes a sealing face, a resiliently deformable portion and a cavity disposed between the sealing face and the resiliently deformable portion, an airway tube extending from a proximal airway tube opening in the proximal end of the neck to a distal airway tube opening in the sealing face of the head, where the resiliently deformable portion is moveable into the cavity from a first uncompressed configuration to a second compressed configuration, and in the second compressed configuration the resiliently deformable portion exerts a restoring force in a direction away from the sealing face of 5.8 N or less.

[0011] Such a restoring force advantageously mitigates the risk of causing trauma within the airway of a patient in use. Such trauma may give rise to inflammation, swelling and / or the formation of blisters. Such consequences may cause the occlusion of the airway or interfere with the desired fitting and sealing of the laryngeal mask in the airway. Embodiments of the present invention therefore mitigate such risks. Moreover, the presence of the resiliently deformable portion allows the laryngeal mask to adapt and fit the airway of patients ofdiffering sizes, thereby avoiding the need for the clinician to match a laryngeal mask of a particular size to a particular patient.

[0012] In certain embodiments, the restoring force is between 0.5 N and 5.8 N, or between 2 N and 4 N, between 2 N and 3 N, or between 3 N and 4 N. In certain embodiments, the restoring force is about 2.5 N or about 3.5 N.

[0013] In certain embodiments, the resiliently deformable portion may be moveable into the cavity up to a maximum extent in which the resiliently deformable portion passes entirely through the cavity and contacts a surface of the head such that further movement into the cavity is prevented, and where the restoring force may be provided when the resiliently deformable portion is moved into the cavity by 10% or more of the maximum extent, by 25% or more of the maximum extent, by 50% or more of the maximum extent, or by 75% or more of the maximum extent.

[0014] In certain embodiments, the resiliently deformable portion may comprise a diaphragm. The diaphragm may be adjoined to the remainder of the head at a first end and a second end and comprises a first side and a second side that each extend between the first end and second end and that are not connected to the remainder of the head.

[0015] In certain embodiments, the diaphragm may have a length between 4 cm and 6 cm (e.g.5.5cm), and / or a width between 2 cm and 3 cm (e.g. 2.4 cm), and / or a thickness of 0.5 cm to 0.6 cm. In certain embodiments, the diaphragm may have a length between 2.0 and 8.5 cm, and / or a width between 0.3 and 6.0 cm, and / or a thickness between 0.3 cm and 2.0 cm.

[0016] In certain embodiments, the head may comprise a first head portion comprising a first material and a second head portion comprising a second material, where the first material is different to the second material. In certain embodiments, the first material and the second material may comprise a common substance but with different material properties (e.g. Shore hardness). In certain embodiments, the sealing face may form at least part of the first head portion and the resiliently deformable portion may form at least a part of the second head portion. In certain embodiments, the first material may have a Shore hardness that is less than a Shore hardness of the second material.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

[0018] FIG. 1 shows a perspective view of a laryngeal mask in accordance with an embodiment of the present invention;

[0019] FIG. 2 shows a detailed view of a part of the laryngeal mask of FIG. 1 ;

[0020] FIG. 3 shows a top-down view of the laryngeal mask of FIG. 1;

[0021] FIG. 4 shows a bottom-up view of the laryngeal mask of FIG. 1 ;

[0022] FIG. 5 shows a cross-sectional side view of the laryngeal mask of FIG. 1 with the resiliently deformable portion in a first uncompressed configuration;

[0023] FIG. 6 shows a cross-sectional side view of the laryngeal mask of FIG. 1 with the resiliently deformable portion in a second compressed configuration; and

[0024] FIG. 7 shows a schematic cross-sectional view of the laryngeal mask of FIG. 1 in situ in a patient.DETAILED DESCRIPTION

[0025] FIG. 1 shows a perspective view of a laryngeal mask 100 in accordance with an embodiment of the present invention. As described in further detail below, the laryngeal mask 100 is configured to be inserted into the airway of a patient so as to facilitate the passage of air into and out of the patient.

[0026] FIG. 2 shows a detailed view of a part of the laryngeal mask 100 as is described further below.

[0027] FIG. 3 shows a top-down view of the laryngeal mask 100, FIG. 4 shows a bottom-up view of the laryngeal mask 100 and FIG. 5 shows a cross-sectional view of the laryngeal mask 100.

[0028] The laryngeal mask 100 comprises a neck 102 that has a proximal end 104 and a distal end 106 and extends therebetween. A head 108 of the laryngeal mask 100 extends from the distal end 106 of the neck 102 and comprises a sealing face 110 for sealing against the larynx of the patient. The head 108 further comprises a resiliently deformable portion 112 and cavity 114 disposed between the sealing face 110 and the resiliently deformable portion 112.

[0029] Throughout the present specification, directions and positions referred to as proximal are at or towards the proximal end 104 of the neck, and directions and positions referred to asdistal are in a direction that extends from the proximal end 104 to the distal end 106 (or beyond).

[0030] An airway tube 116 extends through the neck 102 and the head 108 from a proximal airway tube opening 118 in the proximal end 104 of the neck 102 to a distal airway tube opening 120 in the sealing face 110 of the head 108 (shown in FIG. 4 and FIG. 5). The proximal airway tube opening 118 may be connected to a breathing circuit (not shown) such that, in use when the laryngeal mask 100 is inserted into the airway of a patient, positive pressure may be applied to the lungs of the patient by a ventilation device (not shown).

[0031] In the non-limiting embodiment shown in the figures, a first drain tube 122 also extends through the neck 102 and the head 108 from a proximal first drain tube opening 124 that is towards the proximal end 104 of the neck 102 to a distal first drain tube opening 126 at a distal-most part of the head 108. In use when the laryngeal mask 100 is inserted in the airway of a patient, as described further below, the distal first drain tube opening 126 may be in fluid communication with the oesophagus of the patient so as to be capable of draining any gastric fluid therefrom. The gastric fluid may travel along the first drain tube 122 and out of the proximal first drain tube opening 124.

[0032] A second drain tube 128 also extends through the neck 102 and the head 108 from a proximal second drain tube opening 130 that is towards the proximal end 104 of the neck 102 to a distal second drain tube opening 132 in the head 108 (but proximal relative to the distal first drain tube opening 126). In particular, the distal second drain tube opening 132 is disposed in the cavity 114 such that any fluid (e.g. gastric or other fluids) may collect in the cavity 114 and drain into the distal second drain tube opening 132 through the second drain tube 128 and out of the proximal second drain tube opening 130. The cavity 114 may be preferentially shaped to collect such fluid and direct it towards the proximal second drain tube opening 130 when the laryngeal mask 100 is in its in use orientation.

[0033] The neck 102 and / or the head 108 may comprise a deformable material. The deformable material may include, but is not necessarily limited to silicone. Silicone is particularly advantageous as it maintains sufficient structure to ensure patency of the laryngeal mask 100 whilst enabling some flexibility to facilitate insertion of the laryngeal mask 100 into the airway of the patient.

[0034] The laryngeal mask 100 comprises a bite block 136 at the proximal end 104 of the neck 102. The bite block 136 extends into the airway tube 116 and comprises a more rigidmaterial compared to the material of the surrounding neck 102. Consequently, the bite block 136 maintains the airway tube 116 in an open configuration notwithstanding any force imparted by the patient (e.g. from biting on the laryngeal mask 100 or otherwise) when the laryngeal mask 100 is inserted in the airway of the patient.

[0035] The sealing face 110 comprises a deformable material that is capable of deforming and forming a seal with the larynx of a patient when the laryngeal mask 100 is inserted in the airway of the patient. In certain embodiments, the head 108 may comprise a first head portion 138 and a second head portion 140. The first head portion 138 may include at least the sealing face 110, and the second head portion 140 may include at least the resiliently deformable portion 112. In certain embodiments, the first head portion 138 may comprise a different material to the second head portion 140. In this context, different materials may be different substances, or common substances that differ in their material properties. In particular, in certain embodiments, the first head portion 138 and the second head portion 140 may each comprise a common substance, but the substance of the first head portion 138 may have one or more different material properties (e.g. Shore hardness) to the (common) substance of the second head portion 140. For example, the first head portion 138 may comprise silicone having a first Shore hardness and the second head portion 140 may comprise silicone having a second Shore hardness that is different from the first Shore hardness. In certain embodiments, the first Shore hardness may be less than the second Shore hardness such that the first head portion 138 (and the sealing face 110) is softer and more deformable than the second head portion 140 and more suited for forming a seal with the larynx of the patient. In certain embodiments, the first head portion 138 may have a Shore hardness (A scale) between 0 and 10, inclusive. In certain embodiments, the second head portion 140 may have a Shore hardness (A scale) between 50 and 59, inclusive. In certain embodiments, one of the first head portion 138 and the second head portion 140 may be overmolded onto the other of the first head portion 138 and the second head portion 140.

[0036] In the non-limiting embodiment shown in the Figures, the sealing face 110 includes a deflectable membrane 142 that may deflect towards the larynx of the patient when a positive pressure is applied through the airway tube 116. The deflectable membrane 142 may enhance the sealing of the sealing face 110. In other embodiments, the deflectable membrane 142 may not be present.

[0037] In the non-limiting embodiment shown in the Figures, the head 108 also comprises an epiglottal rest 134 that rests on the epiglottis of the patient when the laryngeal mask 100 is inserted in the airway of the patient. The epiglottal rest 134 may therefore improve positioning and alignment of the laryngeal mask 100 in an inserted configuration.

[0038] The resiliently deformable portion 112 is moveable into the cavity 114 from a first uncompressed configuration (as shown in FIG. 5) to a second compressed configuration (shown in FIG. 6). In the non-limiting embodiment shown in the figures, the resiliently deformable portion 112 comprises a flexible diaphragm (or “beam” or “archway”, such terms being used interchangeably herein) that traverses over the cavity 114 (relative to the sealing face 110), thereby leaving sides of the cavity 114 open. In particular, as shown in FIG. 2, the resiliently deformable portion 112 (diaphragm) is adjoined to the remainder of the head 108 at a first end 144 and a second end 146 and has a first side 148 and a second side 150 that each extend between the first end 144 and the second end 146 and are not adjoined to any other part of the head 108, thereby defining the open sides of the cavity 114.

[0039] The presence of the open sides of the cavity 114 enhances the ability of the diaphragm to flex, and additionally permits the flow of fluid into the cavity 114 so that it may subsequently be drained through the second drain tube 128.

[0040] When the resiliently deformable portion 112 is compressed in a direction towards the sealing face 110 so as to be in the second compressed configuration (as shown in FIG. 6), the resiliently deformable portion 112 exerts a restoring force 602 (indicated on FIG. 6) in a direction away from the sealing face 110.

[0041] FIG. 7 shows a schematic cross-sectional view of the laryngeal mask 100 inserted in the airway 702 of a patient 700. In particular, the laryngeal mask 100 extends through the oral cavity 704 of the patient 700 and is orientated such that the sealing face 110 forms a seal with the larynx 706 of the patient 700. In this position, the distal first drain tube opening 126 is in fluid communication with the oesophagus 708 of the patient 700 and the epiglottal rest 134 rests on the epiglottis 710 of the patient 700. In order to reach the position and configuration shown in FIG. 7 the laryngeal mask 100 must be compressed and deform during its passage through the oral cavity 704 and beyond into the airway 702 of the patient 700. In compressing the resiliently deformable portion 112, the restoring force 602 provided by the laryngeal mask 100 acts to push against a wall of the airway 702 of the patient 700. The restoring force 602acts to maintain the laryngeal mask 100 in a desired position within the patient 700 and, in particular, maintains the seal of the sealing face 110 over the larynx 706.

[0042] In accordance with embodiments of the present invention, the restoring force 602 is 5.8 N or less irrespective of the degree of deformation of the resiliently deformable portion 112 towards the sealing face 110. It is found that restoring forces 602 greater than 5.8 N may cause trauma within the airway 702 and this may give rise to inflammation, swelling and / or the formation of blisters. Such consequences may cause the occlusion of the airway 702 or interfere with the desired fitting and sealing of the laryngeal mask 100 in the airway 702.

[0043] In certain embodiments, the restoring force 602 may be 0.5 N or more (and 5.8 N or less). It is found that restoring forces 602 less than 0.5 N may not be sufficient to provide an adequate seal of the sealing face 110 over the larynx 706. If the sealing face 110 fails to form a seal over the larynx, air provided through the laryngeal mask 100 may not reach the lungs of the patient 700 as desired.

[0044] In certain embodiments, the resiliently deformable portion 112 may be deformable (i.e. moveable into the cavity 114) up to a maximum extent, where the maximum extent is reached when the resiliently deformable portion 112 passes entirely through the cavity 114 and contacts a surface of the head 108 such that further deformation is prevented. In certain embodiments, the restoring force 602 may be between 0.5 N and 5.8 N inclusive when the resiliently deformable portion 112 is deformed by 10% or more of the maximum extent, by 25% or more of the maximum extent, by 50% or more of the maximum extent, or by 75% or more of the maximum extent.

[0045] In certain embodiments, the restoring force 602 may be between 2 N and 4 N, inclusive. In certain embodiments, the restoring force 602 may be between 2 N and 3 N, inclusive. In certain embodiments, the restoring force 602 may be between 3 N and 4 N, inclusive. In certain embodiments, the restoring force 602 may be about 2.5 N. In certain embodiments, the restoring force 602 may be about 3.5 N. Such restoring forces 602 are found to be particularly effective at providing adequate sealing of the sealing face 110 over the larynx 706 whilst avoiding causing trauma to the airway 702 of the patient 700. In certain embodiments, the aforementioned restoring forces 602 may be provided when the resiliently deformable portion 112 is deformed by 10% or more of the maximum extent, by 25% or more of the maximum extent, by 50% or more of the maximum extent, or by 75% or more of the maximum extent. In certain embodiments, deformation of a central 25% of the diaphragm (i.e.between the first end 144 and the second end 146) may determine the above-described maximum extent of the diaphragm.

[0046] The magnitude of the restoring force 602 is determined by the material and form of the resiliently deformable portion 112. For example, the Shore hardness and dimensions of the diaphragm may determine the restoring force 602 provided by the diaphragm when deformed so that part of it moves into the cavity 114. In certain embodiments, the diaphragm may be between 2.0 cm and 8.5 cm long (i.e. from the first end 144 to the second end 146), and / or be between 0.3 cm and 6.0 cm wide (i.e. from the first side 148 to the second side 150), and / or have a thickness of 0.3 cm to 2.0 cm, and / or have a Shore hardness (A scale) of 50 to 59.

[0047] In a specific non-limiting embodiment, the diaphragm may be between 4 cm and 6 cm (e.g. 5.5 cm) long, between 2 cm and 3 cm (e.g. 2.4 cm) wide, have a thickness of 0.5 cm to 0.6 cm, and may have a Shore hardness (A scale) of 50 to 59.

[0048] Whilst in the non-limiting embodiment shown in the figures the resiliently deformable portion 112 comprises a diaphragm, in other embodiments, the resiliently deformable portion 112 is not limited to being a diaphragm, or a diaphragm having the specific features described above, and instead may take on other suitable forms provided that it may be deformed or otherwise compressed so as to provide the suitable restoring force in a direction away from the sealing face 110.

[0049] In certain embodiments, the resiliently deformable portion 112 may have a (outwardly facing) surface area up to 51 cm2(e.g. being 8.5 cm long and 6 cm wide). In certain embodiments, the resiliently deformable portion 112 may have a surface area that is at least 0.6 cm2(e.g. being 2 cm long and 0.3 cm wide). In certain embodiments, the resiliently deformable portion 112 may have a surface area that is from 0.6 cm2to 51 cm2.

[0050] For example, a restoring force of 3.5 N provided by a resiliently deformable portion 112 having a surface area of 51 cm2provides a restoring pressure of 686 Pa.

[0051] The restoring force imparted by the resiliently deformable portion 112 provides a range of restorative forces dependent on the compression of the resiliently deformable portion 112 and its Shore hardness. In certain embodiments, these restorative forces range between zero when the resiliently deformable portion 112 is not compressed, to a maximum of 5.8N at any point in its subsequent full range of travel during deformation, measured at any point on the surface of the resiliently deformable portion 112.

[0052] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0053] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0054] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS1. A laryngeal mask comprising:a neck comprising a proximal end and a distal end, and extending therebetween;a head extending from the distal end of the neck and comprising a sealing face, a resiliently deformable portion and a cavity disposed between the sealing face and the resiliently deformable portion; andan airway tube extending from a proximal airway tube opening in the proximal end of the neck to a distal airway tube opening in the sealing face of the head;wherein the resiliently deformable portion is moveable into the cavity from a first uncompressed configuration to a second compressed configuration, and in the second compressed configuration the resiliently deformable portion exerts a restoring force in a direction away from the sealing face of 5.8 N or less.

2. The laryngeal mask of claim 1, wherein the restoring force is between 0.5 N and 5.8 N.

3. The laryngeal mask of claim 1 or 2, wherein the restoring force is between 2 N and 4 N.

4. The laryngeal mask of any one of claims 1 to 3, wherein the restoring force is between 2 N and 3 N.

5. The laryngeal mask of any one of claims 1 to 4, wherein the restoring force is between 3 N and 4 N.

6. The laryngeal mask of any one of claims 1 to 5, wherein the restoring force is about 3.5 N.

7. The laryngeal mask of any one of claims 1 to 6, wherein the resiliently deformable portion is moveable into the cavity up to a maximum extent in which the resiliently deformable portion passes entirely through the cavity and contacts a surface of the head such that further movement into the cavity is prevented, and wherein the restoring force is provided when the resiliently deformable portion is moved into the cavity by 10% or more of the maximum extent, by 25% or more of the maximum extent, by 50% or more of the maximum extent, or by 75% or more of the maximum extent.

8. The laryngeal mask of any one of claims 1 to 7, wherein the resiliently deformable portion comprises a diaphragm.

9. The laryngeal mask of claim 8, wherein the diaphragm is adjoined to the remainder of the head at a first end and a second end and comprises a first side and a second side that each extend between the first end and second end and that are not connected to the remainder of the head.

10. The laryngeal mask of claim 8 or 9, wherein the diaphragm has a length between 2.0 and 8.5 cm, and / or a width between 0.3 and 6.0 cm, and / or a thickness between 0.3 cm and 2.0 cm.

11. The laryngeal mask of any one of claims 1 to 10, wherein the head comprises a first head portion comprising a first material and a second head portion comprising a second material, wherein the first material is different to the second material.

12. The laryngeal mask of claim 11, wherein the first material and the second material comprise a common substance but with different material properties.

13. The laryngeal mask of claim 11 or 12, wherein the sealing face forms at least part of the first head portion and the resiliently deformable portion forms at least a part of the second head portion.

14. The laryngeal mask of any of claims 11 to 13, wherein the first material has a Shore hardness that is less than a Shore hardness of the second material.

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