Patent Application
20230310782
Described herein are respiratory masks and related accessories. More specifically, described herein is a face shield, patient interface and related methods and uses thereof. The face shield or patient interface may be used for improving a user's breathing.
Many people experience difficulty in sleeping because of breathing problems. These problems may result in snoring, or the more serious condition of sleep apnoea or Sleep Disordered Breathing (SDB). One treatment for Sleep Disordered Breathing involves the use of Constant Positive Airway Pressure (CPAP), bilevel or auto PAP. This involves the use of a CPAP flow generator, a breathing circuit and a CPAP mask (also known as a patient interface). The mask attaches to the patients face, covering the nose and/or mouth in order to deliver positive pressure air to the user. These devices operate to more fully open the breathing passages, thereby allowing for easier breathing.
People who suffer from SDB sleep most nights using their CPAP device and mask. CPAP masks have to be strapped to the user's head, using headgear supplied with the mask, often firmly to create a substantial seal against the users face.
The commonly available, mass manufactured CPAP masks have a flexible silicone seal that contacts the face of the user and a more rigid frame or mask base to support the cushion, connect to headgear straps and the breathing circuit. Examples of such masks are the Fisher & Paykel Healthcare (FPH) HC407 nasal mask and HC431 full face masks, variations of both masks are detailed in U.S. Pat. No. 8,479,726.
Movement throughout the night frequently leads to leaks between the mask and the face (a mask leak), these leaks can wake the user or their bed partner due to the noise generated by the escaping air or the draft that may be directed into the eyes.
Ongoing nightly use of CPAP masks, that typically have flexible silicone seals, can also cause marks and/or pressure sores on the face, commonly on the bridge of the nose. Pressure sores are often caused by commonly available mass manufactured masks are not custom made to the user's facial profile. Mask seals are also commonly called cushions, as they are typically soft and flexible, ‘cushioning’ the masks contact with the users face. They are made to approximate a generic facial profile and are made from flexible silicone, gel and/or foam in order to flex and conform to each user's facial profile. Even small amounts of flexing of the seal from interaction with the face causes pressure on the face and the small amount of pressure applied to the same location on the face over many hours throughout the night, and over many nights, can result in a skin pressure sore.
While the seal or cushion may have a relatively large contact area with the face, often a lot of the force is concentrated in the region of the face that is in contact with the thicker side wall of the seal, or other highly variable regions of the face where the seal needs to deform to match the facial contours, such as the bridge of the nose, resulting in relatively higher pressure in these locations.
Custom made masks that have less flexible seals that fit to the facial contours of the user are available, such the Meta Mason mask detailed in US 2017/0080172, or the custom mask detailed in Thornton U.S. Pat. No. 6,857,428 ('428) may offer an alternative, however as they are custom made to each individual they take a lot of time clinician or technician to manufacture and are therefore very expensive, these designs are not mass manufacturable and cannot be sent directly to the user for contactless self-fitting. The '428 material and product are difficult heat and to handle in their softened state as they do not generally hold their shape, as they have not been crosslinked and therefore lack shape memory. When they are heated they are tacky and require a degree of skill from a technician to fabricate. They do not have a frame to form a handle for the user and provide support to the seal during the user fitting process. They also do not include headgear with optimal connections to the frame to minimise mask movement and leaks and they cannot be re-fitted to other individuals for reuse.
A further problem with commonly available mass manufactured CPAP masks, and in particular nasal and full-face masks, is that they tend to have a relatively large dead space, or breathing chamber, in a rigid frame. This is because the frame must contain enough space to accommodate a range of face and nose sizes, as the rigid frame cannot come into contact with the nose as the seal conforms to the face.
A further problem caused by the use of flexible silicone seals is that they do not provide stability to the mask, as they are flexible. To address this issue masks often have additional features such as forehead pads or cheek pads or rigid side arms to stabilise the mask. These tend to make the mask bulky and can create additional points for pressure sores to develop.
Many patients are also allergic to silicone that is used to manufacture CPAP mask cushions, this can result in rashes or irritation on the face where the mask contacts. There are very few masks that do not have a silicone seal that would provide users with an alternative.
The Resmed application US 2016/0271350 attempts to address the issue of cushion flexibility by inserting a thermoformable material into a silicone cushion. However, the thermoformable material is distant from the users face, there are still extensive regions of the flexible cushion that are not supported by the thermoformable material and the seal does not extend out from the frame in a low-profile manner, making it unstable. The mask still has a large conventional frame making it bulky, creating a large breathing chamber in the mask and is subject to contact with bedding causing movement and leaks. It does not disclose a hard mask seal with significantly increased contact area with the face to reduce pressure applied to the face. The seal thermoformable seal is not cross linked to improve its handling properties and it is not generally flat in cross section, or high aspect ratio, that could distribute the seal forces over a large area of the face.
US 2016/021350 does not disclose a face shield accessory that is designed to be used as with existing masks, where the face shield contacts the face and the mask and silicone seal is placed over it, significantly increasing the surface area of contact with the face to reduce pressure and prevent silicone allergies. The thermoformable material is not have a high aspect ratio so it would not be practical to form it to the face and place a CPAP mask seal over it, as the seal would not align with the thermoformable section. The relatively thick section shown would take a long time to heat up and cool down on the face. It does not teach of a mask seal or face shield that is formed into the general shape of the face and then crosslinked to impart shape memory, before being supplied to the user, to improve its handling, fitting and refitting properties.
Mask liners, such as the RemZzzs masks liners detailed in U.S. Pat. No. 8,365,733 are designed to fit between the users face and CPAP mask cushion, providing a barrier for users with silicone allergies and generally reducing irritation and assisting to create a seal. However, they are a soft, flexible fabric and as such do not reduce the amount of pressure that the silicone seal applies to the face, meaning that pressure sores can still develop.
Other mask liners or gel pads are available such the Boomerang Gel Pad from AG industries or the Resmed nose pad detailed in U.S. Pat. No. 9,999,738 provide a soft gel covering for the skin, however, again they are do not stop pressure being transmitted from the mask cushion to the face as they are flexible, not hard and rigid.
Masks are also used to ventilate patients in a number of settings, such as in hospitals or homes where ventilators are used with masks for non-invasive ventilation (NIV). These masks suffer the same issues as those used for OSA ventilation and hence reference to CPAP or other breathing devices should not be seen as limiting and the apparatus described herein may also be used in other settings that require a mask to form a seal on the face for pressurised breathing, for example in industrial and personal protection applications, such as the 3M 7000 series respirator.
It should be appreciated that it may be useful to provide a face shield or patient interface that attempts to address at least some of the above problems or at least provides the public with a choice.
Further aspects and advantages of the face shield, patient interface and methods and uses thereof will become apparent from the ensuing description that is given by way of example only.
Described herein is a face shield, patient interface and methods and uses thereof that may benefit a user's breathing. The face shield may be manufactured and shaped in a highly customisable manner. In combination with a patient interface, the face shield may provide a superior seal between the patient's face and the patient interface.
In a first aspect, there is provided a patient interface comprising:
The seal may be configured to conform to the contours of the user's face proximate the user's nose.
The seal cross-linked thermoplastic polymer is cross-linked to have a shape memory, the shape memory conforming to a shape of a portion of a person's face.
The seal may comprise an irradiated, cross-linked polymer.
The seal may comprise polycaprolactone.
At least a portion of the frame may be permanently attached to the seal.
The frame may define a breathing chamber in contact with pressured gas, and the seal substantially contacts the user's face in a region outside of the perimeter of the breathing chamber outlet as calculated in the coronal plane.
The frame may define a breathing chamber in contact with pressured gas, and the seal extends beyond the frame breathing chamber outlet perimeter vertically by at least 20 mm as calculated in the coronal plane.
The frame may be configured to be located at least partially superior relative to the tip of the user's nose to hold the seal away from at least a portion of the user's alar during seal moulding to the user's face.
The frame may comprise a material that provides substantial rigidity at temperatures at or below 100° C.
The frame may comprise polycarbonate.
In a second aspect, there is provided a face shield configured for use with a patient interface comprising:
The opening may be configured so that when a first face of the face shield is located on a patient, the opening is located about the patient's nose and/or mouth.
The inner and outer edge(s) may be at least partially curved and/or rounded.
The average thickness of the face shield, measured in a direction perpendicular to a first inner surface of the face shield and between the two opposing faces may be approximately 1 to 4 mm.
The average ratio of the distance between the inner and outer edge divided by the average thickness of the face shield may be from 5-35.
The outer surface of the face shield may be generally planar when viewed in a radial cross section.
The outer surface of the face shield may be generally concave when viewed in a radial cross section.
The common first shape may be generally flat.
The second customised shape may be contoured to follow the patient's facial contours.
The thermoformable polymer may be cross-linked.
The thermoformable polymer may have a melt temperature of 50-70° C.
The thermoformable polymer at 10-30° C. may have a hardness equal to or greater than 15 Shore D.
The thermoformable polymer at 10-30° C. may have a hardness of between 50-60 shore D.
The thermoformable polymer may be an aliphatic polyester.
The thermoformable polymer may be a polycaprolactone polymer.
At least part of the inner surface of the face shield may be configured to contact the patient's face about: a chin region, over a nasal bridge region, a cheek, an upper lip region, and combinations thereof.
The face shield may be configured to prevent contact between a patient interface and a patient's face.
In a third aspect, there is provided a patient interface for supply of gases to a patient comprising:
The face shield may be releasably held between a patient interface and a patient's face in use.
The face shield may alternatively be fixed to a patient interface.
The face shield may prevent contact between a patient interface and a patient's face.
The face shield may form a substantially air tight connection to the patient's face and a substantially air tight connection to the patient interface.
The face shield may extend over the patient's face beyond the frame perimeter.
The frame may be manufactured from a material with a higher melt temperature than the face shield.
The frame material may have a melt temperature equal to or greater than 100° C.
The frame may have a support structure to urge engagement of the frame against at least part of the patient's face.
The frame inlet opening may be directed in an inferior direction and is located substantially posterior to a coronal plane that intersects the tip of the nose.
The frame may have between 25-50 outlet vents to vent gases from the breathing chamber.
The frame shape may be configured so that a patient can hold the frame and face shield thereon and place the face shield and a portion of the frame in water without the patient touching the water.
The frame may have a headgear connector, the headgear connector located on a midline of the frame.
The patient interface may be a nasal patient interface.
Alternatively, the patient interface may be a full-face patient interface.
In a fourth aspect, there is provided a method of customising the shape of the face shield from a common first shape to a second customised shape by the steps of:
The face shield material may become translucent when the melt temperature is reached.
The face shield material may become opaque when it cools to a temperature below the material melt temperature.
In a fifth aspect, there is provided the use, in the manufacture of a patient interface, of a face shield configured to be located intermediate a patient interface and a patient's face, to substantially seal the connection between a patient interface and the patient's face.
In a sixth aspect, there is provided a CPAP, APAP or BiPAP system comprising the face shield substantially as described above.
In a seventh aspect, there is provided a CPAP, APAP or BiPAP system comprising the patient interface substantially as described above.
Selected advantages of the face shield, patient interface and methods and uses thereof may include:
Further aspects of the face shield, patient interface and methods and uses thereof will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:
As noted above, described herein is a face shield, patient interface and methods and uses thereof that may benefit a user's breathing. The face shield may be manufactured and shaped in a highly customisable manner. In combination with a patient interface, the face shield may provide a superior seal between the patient's face and the patient interface.
For the purposes of this specification, the term ‘about’ or ‘approximately’ and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.
The term ‘substantially’ or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.
The term ‘comprise’ and grammatical variations thereof shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.
For ease of reference, the face shield and patient interface is described below with reference to use in a CPAP system. This should not be seen as limiting since the face shield and patient interface may be used for other systems.
The term ‘face shield’ may be used interchangeably with the term ‘seal’ herein.
The term ‘patient interface’ may be used interchangeably with the term ‘mask’ herein.
The terms ‘patient’ may be used interchangeably with the term ‘user’ herein.
It has a rigid frame shown as being cross hatched that supports the seal, an elbow 6 to connect the circuit 4 to the interface, headgear 7 to secure the interface to the patients head and a forehead support 8 to stabilise the interface. The headgear 7 has four points of connection to the frame, however the lower strap of the headgear is shown as being truncated to illustrate other details of the interface.
The flow generator supplies air at positive pressure that flows generally in the direction of the arrows to the patient as well as from the patient to be vented out the bias vent holes shown in the elbow as dots.
It should be noted that the terms ‘interface’, ‘mask’ and ‘mask assembly’ can be used interchangeably and mean the same thing. The terms ‘mask seal’, ‘seal’ and ‘cushion’ when used to describe mask components can be used interchangeably and mean the same thing. Mask ‘base’ is also known as mask ‘frame’ and mask ‘body’. A ‘CPAP mask’ is also equivalent to a ‘respiratory mask’ or may simply per referred to as a ‘mask’. The term ‘air seal’ refers to the action or verb of preventing air or gas from escaping and shall mean the same as the term ‘air connection’ and shall not be confused with the mask component or noun use of the term ‘mask seal’ or ‘seal’.
It should be noted that the description of the geometry, surfaces, sizing and distances described in this specification that related to the thermoformable seal and face shield, unless otherwise stated, relate to their initial mass manufactured form, before they are thermoformed to the users face. Where the face shield or thermoformable mask seal is discussed as forming a substantial air seal with the user's face this occurs after the face shield or mask seal has been thermoformed to the user's face.
All human anatomical references to directions and planes for mask and face shield components are made with reference to the mask or face shield being in use on a user's head and relate to the users head as a reference. The ‘user’ 1 may be a ‘patient’ 1 or a ‘mask user’, for example the latter would apply to an industrial and/or healthcare worker applications of the present invention, where the user may not be considered to be a patient.
It should be noted that all figures in the specification that show the face shield and thermoformable seals from the mask assemblies show these components in their initial mass manufactured form. The figures that show these components on a user's face are not shown in a form that has been thermoformed to the individual users face, as they do not match the exact contours of the image of the head in these figures. It should be understood that in use these components will be thermoformed to the individual users face and will be in close contact with the users face in order to substantially create an air seal between these components and the users face.
Temperature references are made with reference to standard atmospheric conditions, such as pressure, at sea level.
Thermoformable Full Face Mask Face Shield
In a first embodiment, there is provided a patient interface as shown in
The face shield 30 has an outer surface 46 that comes into contact with a CPAP mask seal and an inner surface 47 that contacts the user's face. The inner surface and outer surface are defined by three regions, a nasal bridge region a chin region and a cheek region that is located between the nasal bridge and chin regions. The full-face shield has a generally rounded triangular form and is shaped to match the general contours of the user's 1 face in the nasal bridge region 35, cheek region 36 and chin region 37, but is not initially customised to a particular user's face. Inner surface 47 has a concave form in the nasal bridge region, when viewed through the transverse plane. Alternatively, the face shield may be supplied generally flat and then formed to the contours of the face during fitting.
The face shield 30 may be formed from a low melt temperature, hard thermoplastic material, for example, into the shape shown in
It is also possible to form the face shield by injection moulding and then cutting, for example to form different sizes. They can be formed from flat sheet using vacuum forming and cutting from sheet stock, or simply cutting from flat sheet stock. If sheet stock is used, the sheet may be crosslinked before or after cutting. If formed using vacuum forming it may be useful to crosslink the sheet before vacuum forming to improve the handling properties of the sheet.
After being formed into an initial shape, the face shield material is then crosslinked. Crosslinking improves the handling of the face shield while it is in a softened state for thermoforming to the users face, making it less sticky, holding it generally in its pre-softened shape. Crosslinking can be achieved through the use of irradiation and these details and benefits are further described below.
The face shield is heated to between 50-70° C. ,or to above 60° C., for example by placing it in hot water in order to transition the face shield into its softened, thermoformable state. The face shield turns clear or translucent when it has reached its melt temperature, providing a visual indication that it is ready to be moulded to the shape of the users face. It is then placed on the users face, to form to the contours of the face. The user may need to press the face shield lightly against the face, lie on their back and/or place their CPAP mask over the face shield temporarily to form the face shield to the contours of the face. It then sets on the face as it cools below its melt temperature, thus fitting the face shield to the users face. Providing the face shield with preformed contours of the face (rather than a flat sheet) makes this process easier for the user, as it more closely matched the facial contours before fitting and is less likely to form creases. Alternatively, is it possible to form the face shield from a flat sheet, lowering the cost of manufacture and making it more convenient to ship.
Information such as branding, sizing, company and/or product names may be printed on the inner and/or outer surface, or any surface of the thermoformable seal/face shield. This printing may be the same colour as the cooled device, for example white, so it will not appear in the cooled state, but will appear when the device is heated above its melt temperature as the device turns clear or translucent, revealing the printing, this will highlight the technology and brand similar a water mark. The word ‘Ready’ or symbols such as a tick may be used to further indicate to the user that the product is ready to be fit to the face or trimmed, as they will only appear once the seal is heated above its melt temperature. The printing could also be used to reveal where to cut the product, to change size from large to medium or small or to change product as shown in
The fitted or customised full-face shield 30 is placed on the face and then a full-face CPAP mask, that communicates with the nose and mouth, is placed on top of the face shield. The user's face, face shield and CPAP mask are releasably in contact with each other and the face shield is held in place during use of the CPAP mask by the force the CPAP mask and its headgear apply to the face, in the same manner as shown in
The inner surface 47 of the face shield is configured to be in non-adhering communication with the users face, creating a substantial air seal, or air tight connection, with the face. The outer surface 46 is in non-adhering communication with the seal of the CPAP mask, creating a substantial air seal, or air connection, with the seal of a CPAP mask. Non-adhering means the components are not glued, bonded or stuck together using any form of adhesives or chemicals.
In a variation, the CPAP mask seal may be glued or bonded to the face shield outer surface, adhering the mask seal to the face shield, for example, using an adhesive that will bond with the silicone seal. This will further improve the air seal between the mask and the face shield.
The inner edge 32 extends inward, as indicated by arrows 42, beyond the inner perimeter of the seal contact 39, in order to substantially prevent the interface seal from contacting the face. The perimeter of inner edge 32 shall be less than, or equal to, the inner perimeter of seal contact 39. The inner edge of interface seal generally applies less pressure to the face than the outer edge and the face shield is less sensitive to the issues caused by the inner edge contacting the face through opening 33, therefore, less inner extension is required. For example, the inner edge could be sized to approximately match that of the inner edge of the interface seal or it could extend up to 10 mm per side in from the inner perimeter of the seal contact 39. It should be noted that as the interface seal is applied to the face it can becomes wider, so an initial spacing between the outer edge of 20 mm, while not in use, could become 2 mm while in use.
The outer surface 46 of the face shield may be generally flat in radial cross section, for example, in the cheek region shown by radial cross section B-B of
The following dimensions relate to the overall widths and heights of a medium sized full-face shield that is sized to fit a medium size full face CPAP mask. The full-face shield should be 95-115 mm wide (lateral direction), or 100-110 mm wide. It should be 130-150 mm high (superior/inferior direction) for a version with a chin support 34. A version without a chin support should be 110-125 mm in height. Opening 33 should between 65-75 mm in height and 50-60 mm wide. The radial distance 43 and 44 from the inner edge 32 to the outer edge 31 in the nasal bridge region and cheek region should be between 20-35 mm, measured in the general plane, or major axis, of the outer surface 46 at each location. The distance 45 in the cheek region should be between 20-35 mm for a face shield without a chin support 34 or between 35-55 mm for a face shield with a chin support, as measured in the coronal plane.
The small sized full-face shield will have similar width dimensions to the medium size but be 5-15 mm less in height. The large sized full-face shield will also have similar width dimensions to the medium size but be 5-15 mm more in height. The change in height shall apply to both the outer height and the height of opening 33.
The thermoplastic should be relatively hard (and hence rigid) while in use at room temperature or up to body temperature. The face shield should be hard in order to distribute the forces that the mask and seal apply to the face over a large area to reduce the pressure applied to the face. The harness should be at least 15 Shore D (ASTM D 2240 55) or 50-60 Shore D.
The face shield can be used as an accessory with currently available CPAP masks and prevents or reduces contact between the silicone seal and the users face reducing silicone skin irritation and pressure sores. The face shield provides a rigid shield, or barrier, between the face and the CPAP mask that is placed over the face shield. The face shield covers the face in a similar manner to that of a traditional fabric mask liner, however as it is thicker and more rigid it more evenly distributes the CPAP mask or interface sealing forces over a larger area, reducing the pressure applied to the face from the interface. Gel pads are thicker however, they are also very flexible and do not distribute the seal forces over as large an area as the hard face shield. The face shield also allows the CPAP mask to be tightened more if necessary, increasing the masks seal contact area and improving the seal without causing discomfort as the force is distributed over the larger contact area of the face shield. These advantages are further described below.
The contact area between the face and the face shield is 60-140% larger than the typical contact area between a mask cushion and the face and the increased area provides improved sealing performance. This increased contact area can improve the sealing performance over difficult regions of the face, such as the bridge of the nose or areas that may be creased due to age or covered by facial hair such as users with moustaches.
Furthermore, as the face shield does not bond or stick to the face in the manner that gel pad does, it allows small amounts of air to pass between the face and the face shield throughout the night, allowing the skin to breath, reducing irritation and sweating. It should be noted that this small amount of leakage, that may be in the order of 5 litres per minute at 10 cm H2O pressure will not interrupt therapy and is much smaller than would be considered an undesirable mask leak, this is still considered to be a substantial air seal or air connection.
The face shield is available in a range of sizes, for example, small, medium and large, corresponding to small, medium and large masks. It is also available in a range of mask styles such as for full face masks, nasal masks, nasal pillow masks, hybrid nasal-full face masks and total face masks that additionally contact and seal above the eyes. The face shield may also be used in combination with anaesthesia masks or where gasses have to be applied to the patient during an operation. This may be of particular benefit where the patient as a facial injury, burn or sensitivity that may be aggravated by direct contact with the mask, or a facial deformity that a conventional mask may have difficulty matching and sealing on.
The inner and/or outer surfaces of the face shield or thermoformable seal may be smooth or have a frosted texture. The frosted texture may provide a more comfortable surface for skin contact and a surface that is less sticky to the silicone seal reducing creases in the seal. The inner and outer surfaces may additionally have one or more groves or protrusions running generally parallel to the outer or inner edge, in a concentric manner. These grooves or protrusions may be 0.5-2 mm deep or high and run partially or entirely around opening 33 or breathing chamber of mask. The grooves or protrusions may be in the form of a half round, square or rounded triangular shape. The benefit of the grooves or protrusions is that they may improve the sealing performance between the outer surface and the mask seal and/or the inner surface and the face by creating localised points of increased contact in a similar principal to tread on a car tyre. These grooves and/or protrusions may not be located on the inner surface in the nasal bridge region and the skin is thinner there and may not tolerate such features, where as other areas such as the cheek or chin would tolerate such features. The groove and protrusion features only apply to the inner, face contacting region of the thermoformable mask seal.
The face shield may have its own headgear strap, or straps, similar to that of a CPAP mask in order to be self-secured to the users face. The straps may also assist the face shield to act as a chin support, reducing mandible movement and mouth leak.
Thermoformable Nasal Mask Face Shield
In a second embodiment, there is provided a patient interface is shown in
It will be appreciated, by someone skilled in the art, that the general description of the full-face shield design, function and benefits also apply to the nasal mask face shield.
The following dimensions relate to the overall widths and heights of a medium sized nasal face shield that is sized to fit a medium nasal CPAP mask. The nasal shield should be 60-80 mm wide (lateral direction) or 65-75 mm wide. It should be 65-85 mm high (superior/inferior direction) or 70-80 mm wide. Opening 53 should between 30-50 mm in height and 30-50 mm wide. The distances 63, 64, 65 from the inner edge 52 to the outer edge 51 in the nasal bridge 35, cheek 36 and upper lip 57 regions should be between 15-30 mm, measured in the plane of the outer surface 66 at each location.
The small sized nasal mask shield will have similar width dimensions to the medium size but be 5-15 mm less in height. The large sized nasal face shield will also have similar width dimensions to the medium size but be 5-15 mm more in height. Again, height changed apply to the external height and the height of opening 53.
Thermoformable Combination Full Face and Nasal Mask Face Shield
Face shield 70 has a nose opening 73a and a mouth opening 73b, defined by two inner edges, nasal inner edge 72a and mouth inner edge 72b. The two openings allowing communication between the CPAP mask and patients airways via the nose and mouth. Face shield 70 has upper lip cross member 88 that covers the upper lip 57 thus shielding contact between the upper lip and the lower section of a nasal mask seal. Face shield 70 can also contour under the users chin in the same manner as detailed in the first embodiment. Thus, it may assist in stabilising the mandible or jaw, keeping it closed for nasal mask and/or full-face mask users, preventing the need for a chin strap.
If nasal mask users do not want the under-chin support region they can cut face shield 70 through region indicated by the doted lines (89a and 89b), thus creating a nasal mask face shield similar to that shown the second embodiment. The doted lines 89a and 89b may be marketed on the outer or inner surface of the face shield, for example, by laser marking, printing to formed during injection moulding, in order to indicate, to the users, the region to cut. Alternatively, if a full-face mask user did not want cross member 88 they could cut through the region indicated by the doted lines 90a and 90b, thus creating a full-face shield similar to that shown in the first embodiment. This may be useful design as it would reduce the variations or SKU's that need to be tooled, manufactured and distributed. Doted lines 90a and 90b may also be marketed on the face shield in the same manner as described for doted lines 89a and 89b.
Another variation of the face shield 70 may have no opening 73b. This would serve to cover the mouth preventing or reducing air leakages from the mouth while the user was wearing a nasal mask or nasal pillow mask.
Thermoformable Nasal Pillow Mask Face Shield
In a fourth embodiment, there is provided a patient interface comprising a thermoformable nasal pillow mask face shield that is an accessory to be used with other readily available nasal pillow CPAP masks that have silicone, gel, foam or generally soft seals. The nasal pillow mask face shield would contact the nose around the user's nares to prevent contact between the silicone seal of the nasal pillow mask and the user's nose. It will be appreciated, by someone skilled in the art, that the general description of the other face shield embodiments design, function and benefits also apply to the combination nasal pillow mask face shield.
The nasal pillow mask face shield may additional contact the upper lip, in a similar manner to the nasal mask face shield, and/or the tip of the nose to further reduce contact with the mask and stabilise the face shield. In addition, it may also contact the cheek region to provide further support.
The nasal pillow face shield may have two openings that allow each individual pillow of the nasal pillow mask to communicate with each nares. Alternatively, it may have one opening that communicated with both nares, for masks that primarily contact the nose around the nares, do not contact the nasal bridge region, and have only one outlet from their seal, such as the FPH Evora nasal mask.
Thermoformable Nasal Bridge Face Shield
In a fifth embodiment, there is provided a patient interface comprising thermoformable nasal bridge face shield that is an accessory to be used with other readily available full face or nasal CPAP masks that have silicone, gel, foam or generally soft seals. The nasal bridge face shield contacts the nasal bridge and cheek region of the users face, in the same manner as the gel pad shown in U.S. Pat. No. 9,999,738
The nasal bridge face shield is generally in the form of an inverted letter “V”. The lower (inferior) and lateral edges of the nasal bridge shield may be tapered down to be thinner than the general thickness of other regions. The tapered region may end at a point or have a small radius. A point 1 mm from the edge should be no thicker than 1 mm. This tapering corresponds to the region where the CPAP mask seal passed from the nasal bridge seal to the users face. The benefit if this tapered region is to allow the CPAP mask seal to transition from the outer surface of the face shield to the users face without encountering an abrupt step that may air leaking from this region. The taper can be on the inner surface, outer surface or both surfaces. The tapered region will be at least 2 mm long and at least 5 mm long.
Polycaprolactone—Low Melt Temperature Hard Thermoplastic Material
The face shield or CPAP mask/interface seal may be constructed from Polycaprolactone (PCL) polymer or by using another aliphatic polyester. One or more of the polycaprolactone polymers may have the formula:
Where R is an aliphatic hydrocarbon.
TONE polycaprolactone polymers are described in U.S. Pat. Nos. 4,784,123 and 5,112,225 and product literature of Union Carbide Corporation, all incorporated here by reference, as including homopolymers, block copolymers graft copolymers, or other polymers containing epsilon-caprolactone. Polymerization may be initiated using a diol, for example and without limitation, ethylene glycol, diethylene glycol, neopentyl glycol, butane diol, hexane diol, or any other appropriate diol.
PCL is also known as Poly(hexano-6-lactone), 2-Oxepanone homopolymer and also 6-Caprolactone polymer and has a density of 1.14-1.15 g/cm3.
Another example of a suitable PCL polymer is CAPA 6500, a thermoplastic linear polyester derived from caprolactone monomer. CAPA 6500 is supplied by Perstorp with a mean molecular weight of 50,000 and a melting point of 58-60° C.
Polycaprolactone is a relatively hard plastic, with a Shore D hardness of 55, or between 50-60. As calculated at 25° C. or as stipulated in ASTM D 2240 55. This makes it very tough, for example, like nylon, it but softens to a putty-like consistency when heated above 58-60° C., for example by placing it in hot water. This low melt temperature enables it to be handled and placed on the face without burning the skin or causing discomfort. Polycaprolactone also has a relatively low heat capacity, relative to water, which further reduced the amount of energy that can be transferred to the skin during the thermoforming process. Furthermore, as it has a relatively low rate of thermal conductivity any energy or heat transfer to the skin is slow.
As polycaprolactone is hard and rigid when cooled, at room or skin temperature, relative to commonly used low temperature human body mouldable materials like EVA, therefore less volume of PCL is required to achieve the desired mechanical properties of the product, such as flex or strength. This lower volume further improves the handling properties by reducing the amount of energy in the heated product, reducing heating and cooling times and reducing the amount of energy that could be transferred to the user's skin during fitting.
The polycaprolactone has a melting point of 58-60° C. This enables the face shield or seal to be softened, for example by placing it in hot water, and comfortably placed on the face without burning the face and not become soft during use due to contact with the face that may be about 37° C.
Most relatively rigid thermoplastics have a melting temperature between 100-300° C. and would burn the face if used in this manner. Other thermoplastics are available that have a melt temperature below 100° C., such as Ethylene-vinyl acetate (EVA) that is commonly used is mouldable sports mouth guards. However, EVA still has a higher melt temperature of between 90-120° C. which is higher about 50% than the melt temperature of PCL. The melt temperature can be lowered with different EVA blends or with the addition of plasticisers however this lowers the hardness further below desired levels, and plasticisers are often not biocompatible. EVA is relatively flexible and would not have the required rigidity to provide the desired level of support to prevent localised cushion forces acting on the face, unless they were very thick that would result in a product that was too bulky to practically use.
The PCL can also be blended with other materials to create a blended materials, or copolymers, for use in forming the seal or face shield with a different feel on the skin. Any suitable blend should have a melt temperature between 50-70° C. and a hardness of more than 15 Shore D or a hardness between 50-60 Shore D.
Crosslinking-Irradiation and Shape Memory
Crosslinking the face shield, or mask seal, imparts shape memory into the part. This means when the face shield is heating above its melting temperature of 60° C. it becomes soft but still holds its general shape. Without crosslinking it is very difficult to handle the melted material as it would tend to flow like a thick liquid and not hold its general form. Crosslinking allows the material to be in a softened state, above its melt temperature, while still retaining its general form, so it can be placed against the face and formed to the shape of the face.
The crosslinked polycaprolactone is then allowed to cool below its melt temperature of 60° C. This can take between 1-4 minutes, while the part is in contact with the face, thus setting into the form of the user's facial profile and hence being customised to the user. Crosslinking will also provide shape memory allowing the face shield to return to approximately is original injection moulded form after being reheated above its melt temperature, allowing it to be heated and refit to the same or a different users, a large number of times, without degradation of its form or mechanical properties.
After being injection moulded into its initial non-customised form the face shield or CPAP mask/interface seal undergoes irradiation to crosslink the polymer chains. Crosslinking can be achieved through the use of gamma radiation or electron beam (E-Beam) radiation or any other known methods. E-Beam crosslinking allows for more precision and uniformity of the absorbed radiation does.
Crosslinking is the interconnection of adjacent long molecules with three-dimensional networks of bonds (crosslinking) induced by chemical treatment or electron-beam (E Beam) treatment. Electron-beam processing of thermoplastic material results in an array of enhancements, such as an increase in tensile strength and resistance to abrasions, stress cracking and imparts three-dimensional shape memory into the product. E Beam treatment rather than chemical treatment allows the product to be crosslinked in its final moulded form, for example the seal and frame that have been over moulded to each other, without adversely affecting the properties of the frame, that does not need to be crosslinked, but must be subjected to the crosslinking process as it is bonded to the seal.
It should also be understood that this crosslinking of the injection moulded or otherwise formed component is very different from the crosslinking of raw plastic material for injection moulding. Crosslinking of raw materials does not produce three dimensional components that have shape memory as the material was not crosslinked in its final form.
The crosslinking of polymer chains through electron-beam processing can change a thermoplastic material into a thermoset. When polymers are crosslinked, the molecular movement is severely impeded, making the polymer stable against heat. This locking together of molecules is the origin of all of the benefits of crosslinking, including imparting three-dimensional shape memory.
Conventional thermoset plastics or elastomers cannot be melted and re-shaped after they are cured. However, crosslinking polycaprolactone to the desired level of the present invention results in a material that has properties of both a thermoplastic and a thermoset material, or somewhere between the two. It can be heated above its thermoplastic melt temperature of 58-60° C., but in this semi-molten state it retains its three-dimensional form. It behaves somewhat like a very soft rubber material, or putty, for example with hardness of less than 10 Shore A, which is significantly less that the hardness of commonly available CPAP mask silicone seals that are typically 40 Shore A. The material can be handled and formed into different shapes, for example the shape of the nose or face and therefore still has thermoplastic properties. Once cooled it sets into that shape and returns back to its original harness of between 50-60 Shore D.
This property is achieved by applying the desired amount of radiation to achieve some level of crosslinking but not too much. Too much radiation would result in too many crosslinked bonds forming that may make the material too hard and not easily mouldable to the face when heated above its melt temperature or may degrade the material or other mask components. Not enough radiation would result in not enough crosslinked bonds forming and the material would not have sufficient three-dimensional shape memory and would be difficult to handle above its melt temperature, it would lose it shape and be sticky or tacky.
The amount of radiation applied should result in an absorbed does of between 4-40 kGy, or between 6-24 kGy. The Gray (symbol: Gy) is a derived unit of ionizing radiation dose in the International System of Units (SI). It is defined as the absorption of one joule of radiation energy per kilogram of matter
Product dose absorption is dependent on the characteristics of both the electron beam and the product itself. As the electron beam enters the product being irradiated, dose is absorbed in the product. The absorbed dose will vary as a result of the uniformity of the product. Generally, the orientation of products for electron beam processing is chosen so that the thickness through which the electron beam passes is less than the depth where the exit absorbed dose is equal to the entrance dose. For 12 MeV electrons this corresponds to approximately 4 g/cm2. The total dose may be applied as a single sided dose or as a double-sided dose.
Electron-beam processing also has the ability to break the chains of DNA in living organisms, such as bacteria, resulting in microbial death and rendering the space they inhabit sterile. E-beam processing has been used for the sterilization of medical products. While sterilization of these products may not be required, and is not the primary purpose for the E-Beam processing, it could be an added benefit as the products can be E-Beam processed in their final sealed packaging.
Seal Thermoforming and Force Distribution on the Face
When heated to above its melt temperature of 58-60° C., the face shield, or CPAP mask seal, has a hardness of less than 10 Shore A or as low as 20 Shore 00. This is less than a CPAP mask silicone seal that are typically 40 Shore A. Human skin has a typical hardness of 20-30 Shore 00.
This lower hardness, in the mouldable state, causes less compression of the skin on the face when the seal is placed on the face, for fitting and thermoforming, relative to a traditional CPAP mask. The mouldable seal sets once it cools to below its melt temperature of 60° C., into a shape that matches the contours of the users face while causing less deformation or compression of the skin relative to that caused by a traditional CPAP mask silicone seal. Once set the mouldable seal has a hardness of more than 15 Shore D or between 50-60 Shore D and as it is not subject to as much deformation as a silicone seal, therefore it more evenly distributes the forces over a larger area of the face resulting in lower pressure being applied to areas of the face and hence leads to less pressure sores forming on the users face.
As can be seem in
For example, the approximate significant force contact area of a traditional full-face mask silicone seal is approximately 25 cm2. This significant force area, where at least 80% of the force is applied, is less than the total seal contact area 40, as discussed above, and is an estimate of the area where most of the force is applied, for example underneath or close to the vertical walls of the seal or thicker areas of the seal. The approximate contact area of the medium full-face mask face shield is 100 cm2, which is 4 times greater than the traditional full-face silicone seal significant force area. Therefore, for the same applied force the pressure applied to the face will be on average 4, or between 3-5, times less while using the face shield or mask of the present invention.
In summary, the significant force area of full-face seal contact is a measure of the higher or peak pressure areas, and the total seal contact area 40 is a measure of the overall or average pressure applied by the mask. This provides two means of assessing pressure area, one being higher pressure areas and the other average pressure areas. The average is more straight forward to calculate as it is a simple measure of the total seal contact area.
Mask Assembly
Mask assembly embodiments of this invention, shown in
As the hard thermoformable seal provides a mask assembly that is inherently stable, it may not need to have the peripheral stabilising features, such as three or four headgear connections located around the periphery of the mask or a forehead support that are typically required to provide masks with stability. As the mask has a hard, rigid seal it cannot easily be pulled sideways as the seal will not collapse or flex like a standard silicone cushion seal.
The frame supports the form of the cushion during the heating and moulding to the face. It also forms a small internal breathing chamber below the nose. The breathing tube connection to the mask frame can be located below the nose, in a downward direction, and does not extend out significantly beyond the tip of the nose, resulting in a very low-profile mask.
Such an arrangement provides a mask that is less obtrusive as it does not have the peripheral stabilizing features, a large breathing chamber that protrudes from the face and a bulky flexible seal. It also has improved air sealing properties and creates less pressure points on the face. This allows users to more freely sleep on their side or partially face down into the pillow without the mask being dislodged by a traditional bulky elbow connection.
Mask assembly 100 is placed on a user's 1 face to create an air seal and is connected via a breathing circuit to a CPAP device in the same general manner as mask 2 of
Nasal Mask Assembly
Thermoformable Seal
The seal 110 is formed from a low melt temperature, hard, thermoformable plastic material. The seal material may have a melting temperature between 50-70° C. The thermoformable material is also relatively hard (and hence relatively rigid) when in a set or cooled state, for example it should have a harness of more than 15 Shore D, or 50-60 Shore D. Most CPAP masks use a silicone with an approximate hardness of Shore A 40, that is a significantly softer scale than the minimum value of the Shore D scale. It should also be noted that silicone in not a thermoplastic, it is a thermoset material and cannot be heated and thermoformed from its original shape.
As the seal is not required to curve in on itself, where it contacts the face, to create a seal using air pressure as common silicone seals do, as shown in
The thermoformable seal 110 extends out, in a radial direction, measured in the coronal plane, from the frame in at least one of the nasal bridge or cheek regions, contouring to these regions forming a low-profile seal formed to match the general contours of the face but is not customised to a particular users face.
The thermoformable seal 110 is 1-4 mm thick, or between 2-3 mm thick, in the direction that is perpendicular to the face contacting surface of seal 110.
The outer perimeter of the seal 110, where it contacts the face, projected onto the coronal plane forms a projected seal area. The outer perimeter of the frame 120, where it forms the breathing chamber, excluding any tube connection 127 feature, projected onto the coronal plane forms a projected frame area. The seal projected area of the sixth embodiment is approximately 20 cm2 and the projected area of the frame is approximately 10 cm2. The ratio of nasal mask seal area to frame area is approximately 2 or in the range of 1.5-2.5. A conventional CPAP nasal mask, for example the HC407 has a projected seal area where it contacts the face of approximately 15 cm2 and a frame breathing chamber projected area, e.g., excluding the forehead support, of approximately 20 cm2. The ratio of seal to frame area is approximately 0.75. The seal/frame larger ratio of the present invention is possible as the seal is hard and does not need to be supported over a large area by a frame, leading to a more compact breathing chamber and mask.
The thermoformable hard seal allows the mask frame 120 to be significantly smaller and may be located substantially below the nose (in an inferior direction relative to the tip of the nose). The above features combine to make the mask very low profile on the face, as can be seen comparing the side view of the conventional mask shown in
The thermoformable seal 110 may be injection moulded from polycaprolactone as detailed herein.
The Seal 110 is crosslinked after injection moulding, before being customised to a specific users face, to impart shape memory into the seal, allowing the seal to hold its moulded shape, without significant unwanted deformation, thus improving the handling and fitting of the mask, allowing untrained users to fit their own mask. These details and benefits are described above.
The mask can be heated to above 60° C. for example by placing it in hot water, to soften the seal, but not softening the mask frame, in order to place the seal on the users face to form it to the contours of the particular users face. During this process the frame does not substantially soften and acts to provide support to the seal and act as a handle for the heating and fitting process. The seal forms a substantially air tight connection to the users face after being moulded to the shape of the user's face and cooling below its melt temperature or below 50-70° C. Further benefits of mask and fitting process are described in the section.
Once set the mask seal matches the contours of the users face, and applies the mask retention force over a large area of the face, improving the sealing performance and reducing the peak pressure applied to the face by a factor of 3-4 relative to conventional silicone seal masks or to reduce the average pressure applied to the face by a factor of 1.4-2. The basis of this calculation is the same as described in the face shield section.
As the seal is hard and rigid the mask is inherently stable and does not need additional features such as a forehead support or rigid side arms to provide stability.
In a variation of the sixth embodiment, the nasal mask seal 110 may additional extend down from the upper lip to cover the mouth, preventing air for leaking out of the mouth. The seal could extend between 30-90 mm in an inferior direction, over the mouth and/or under the chin to both cover the mouth and provide a chin support, to prevent the mandible from lowering and the mouth from opening. This seal could also extend under the chin while having and opening for the mouth, enabling the user to breathe through their mouth while providing chin support. Additional headgear connections to the lower region of the mask may be added to support the lower region of the mask or the connection point for the headgear may be lowered. This mouth covering variation may also include a non-rebreathing valve for safety as the mouth is covered.
Thermoformable Seal to Frame Connection
The frame may be injection moulded and then the seal is injection moulded over the frame, this process is called over moulding or insert moulding and can result in a bond between the seal and frame that is chemical, mechanical or a combination of the two. The seal could also be formed separately and then bonded or glued to the frame. The combined frame and seal form a unit that improves seal handling during the heating the thermoforming fitting process. It is not practical to have a separate seal 110 without a bonded higher temperature frame or clip as the seal 110 region that connects to the frame would distort during the user thermoforming process and would not be able to connect to the frame or clip after thermoforming.
The seal may additionally be over moulded with a layer of silicone or EVA, substantially incapsulating the seal, in order to give the mask seal different texture or feel on the face. This version would only be suitable for users that do not have silicone allergies. The layer of silicone or EVA would be relatively thin, in the range of 0.5-2.0 mm and would not be allowed to flex independently of the thermoformable seal 110 material, so seal 110 would still retain it generally rigidity to support itself without the need of an extensive frame to support it over most of its area.
Alternatively, the seal may be over moulded, or bonded, to a connection mechanism, such as a seal clip or cushion clip. The clip can be formed from the same type of high temperature, rigid materials that can be used to form the frame. The combined seal and clip form one unit that can then be connected to the frame. This connection can be permanent, for example it can be glued, welded or permanent clipped together or it can have a releasable snap fit connection, enabling users to easily remove the seal from the rest of the mask assembly for cleaning or changing to a different size of seal or even a different type of mask, for example changing from a nasal mask to a nasal pillow or full face or any combination of these. U.S. Pat. No. 10,272,218, incorporated entirely by reference here, describes a suitable cushion clip, for example bridging portion 50 or clip 442, for connecting the cushion to the frame or mask body.
For example,
Frame
Using a frame material that has higher melt temperature allows the combined frame and seal unit to be placed in boiling water, or hot water between 60-100° C., without melting the frame, enabling the frame to provide support to the seal and providing a rigid component that acts has a handle for the user in the heating and thermoforming fitting process.
The user may hold frame by the tube connection 127 and/or the lateral side walls of the frame, that form a handling region 132 of the frame the does not need to be entirely submerged in hot water while allowing seal 110 to be fully submerged in order to raise its temperature to or above 60° C., in order to bring the seal to a thermoformable state.
Breathing Circuit or Tube connection to Frame
The frame includes an inlet opening 121 and tube connection 127 adapted to receive a short flexible breathing tube 170 or the main breathing tube 4 directly. Alternatively opening 121 and/or tube connection 127 may connect to an elbow and/or a swivel joint.
Opening 121 is located at least partially, or substantially, in a posterior direction relative to the tip of the nose. This reduces the amount the mask assembly protrudes out from the face, in an anterior direction. Many CPAP masks have elbows that protrude in an anterior direction from the frame, as can be seem in
Headgear and Headgear Connection to Frame
Alternatively, connector 160 need not have a sliding connection, but may have the same general low-profile connection and form.
Headgear connector(s) 124 are located near the centre of area of the seal, as calculated in the coronal plane, which is generally over the tip of the nose for a nasal mask, as shown in
As shown in
Connecting the headgear to the mask frame, near the tip of the nose, or on the midline, is advantageous when compared to connecting the headgear to the periphery of the frame or seal, near the surface of the face in the cheek region. This is because force vector A1, acting near the centre of seal area, is more likely to act in a posterior direction within the outer periphery of the seal 110, leading to inherent stability of the mask with a hard thermoformable seal.
A further advantage is created as headgear vectors B1 and B2 act in more of a posterior direction creating a higher magnitude sealing force vector A, when connected near the tip.
When connected near the surface of the face, for example, in the cheek region, the headgear straps create vectors that act more in a lateral direction, as they have to curve around the cheeks changing the angle of connection to the mask, resulting in higher headgear tension forces being required to produce force vector A with the same magnitude compared to the mask described herein that connects the headgear distant from the surface of the cheek region. Connecting near the cheek region produces a mask with less stability and poorer sealing performance relative to a central connection described in this embodiment. In addition, including headgear connectors in the seal may lead to poor thermoforming to the face in the region resulting in discomfort and/or leaks between the seal and the face.
Additional suitable headgear and headgear to mask base (frame) connection designs are disclosed in U.S. Pat. No. 9,320,866 ('866), incorporated here entirely by reference, for example headgear 21 that includes curved and elongate member 34 and its connection to the mask base 22, as well as headgear 300 and that of the ninth full face mask embodiment. The mask described herein may not need the stabilising features of '866 however cured and elongate member 34 and its equivalent versions may be useful in changing the headgear vectors, directly them away from the eyes and allowing all rear straps to pass over the top of the ears for ease of placing the mask assembly on and off the face for the nasal and nasal pillow versions.
Stabilizing Mechanism
The upper lip support 129 may engage the upper lip directly or may be covered by the thermoformable seal 110 material, as shown in
The upper lip support is designed to provide a reference point for the mask assembly during the thermoforming fitting process by transferring forces through the upper tip to the patient's maxilla. This stabilises the mask assembly in the correct posterior—anterior location and reduces rotation in the sagittal and coronal planes. The upper lip support may be contoured to the shape of the upper lip, for example, it may be concave in shape and may include a recess shaped to accommodate the nasal septum, as indicated by radius R in
Alternatively, the frame 120 may include an alternative to the lip support, such as a cheek support, or nose tip or nose bridge support, that contacts the user in the cheek, nose tip or bridge region, providing the same function as the lip support, that is a reference point for fitting the mask, using the cheek bones instead of the maxilla. Furthermore, temporary structures such as forehead supports or rigid side arms could be used as reference points during fitting and could be removed after the fitting process has been completed. The frame 120 includes one of the following combinations (a) an upper lip support 129 only, (b) an upper lip support 129 and a cheek support, (c) an upper lip support 129 and a nasal bridge support. Support structure should not include all three of these features as due to facial variation amongst users these points will vary resulting in fitting difficulties as the rigid frame will not match these land marks on many users.
Gas Washout
The openings or holes may be additionally covered with a filter medium to further diffuse and quieten the gas vent flow and/or to filter water droplets, aerosols, bacteria and viruses from the venting air, reducing contamination of the surrounding environment that may affect others. The filtering of the vented air will benefit both respirator masks applications as well as industrial and personal protection mask applications. U.S. Pat. No. 6,662,803, discloses suitable outlet vent designs including apertures 302, a frame member 306 and filter medium 308.
Alternative Nasal Mark
It should be noted that calculations relating to the projected area of the frame breathing chamber, or frame outer perimeter, should exclude the forehead support 133, headgear connectors 124 and tube connection 127, lib support 129, or other features where they extend beyond breathing chamber 128 outlet. As frame 120 of mask 100, shown in
Frame 120a may have a mask logo and/or company brand over moulded onto it during the seal 110 moulding process. This would form a logo or brand in the same material and hence colour as the seal. This logo could be moulded into a recess, or embossed region of frame 120a. PCL is often white or coloured and this will stand out against a clear frame. During the heating process the logo or brand will go above the melting point of the polycaprolactone and become transparent or semi-transparent providing further visual indication that the seal is ready to fit to the user's face. Other symbols or messages such as ‘ready’ could be conveyed to the user in the same manner as the logo or brand.
The thickness of seal 110 may vary, for example the seal region that is located near the users alar or other soft tissue regions around the tip of the nose, may be thinner, for example in the range of 0.3 mm-1.2 mm. This allows the seal to fit to this region while reducing pressure applied to the alar reducing narrowing of the nares during fitting that could lead to breathing restriction.
The seal outer perimeter 115 could also have a reduced thickness in order to allow the perimeter to flex slightly reducing pressure on the user's face at the seal perimeter caused by mask movement. The average thickness near seal outer perimeter could be reduced to between 0.3-1.2 mm over the region 2-5 mm from the perimeter of the seal. The region 0-2 mm from the perimeter may also be reduced or may be thicker than 1.2 mm to avoid a sharp edge forming at the seal perimeter. The thinner region of between 0.3-1.2 mm, located 2-5 mm form the perimeter, will allow the perimeter to be thicker while still providing flex for comfort.
Seal 110 or frame 120 may have curved and elongate members, formed from the thermoformable seal 110 material, such as polycaprolactone, extending from the seal or frame in order to connect to headgear. Examples of suitable curved elongate members 34 are disclosed in U.S. Pat. No. 9,320,866 ('866). Curved and elongate members may be formed integrally with the seal or frame over moulding process or may be mechanically or chemically connected. Curved and elongate members can have a region that has a thickness of less than 2.0 mm near its connection to the seal or frame to allow the member to flex to the facial profile of individual users, for example over the cheek or forehead region. Alternatively, curved elongate members may not have a thin section for flexing as they can be thermoformed to each individual user. Such members will also be cross linked for shape memory providing the same advantages as disclosed for seal 110. The use of curved elongate members for connection to headgear can provide additional stability to the mask.
Headgear connectors 124 may be located in seal 110 or in curved elongate members and may be formed from a material that has a melt temperature above 100° C., such as the materials used to form rigid frame 120. This enables headgear connectors 124 to maintain their form, for connection to headgear or headgear clips etc, during heating and thermoforming to the users face. Headgear connectors could be injection moulded from rigid materials and then over moulded by the low temperature thermoplastic material that forms seal 110 during the seal 110 or elongate member injection moulding process. Alternatively, they could be mechanically or chemically connected. Having headgear connectors on seal 110 or elongate members provides a lower profile connection between headgear 180 and seal 110 or frame 120. Lower headgear connectors 124 may be located in seal 110 or elongate members while upper headgear connectors 124 may be located in frame 120 as they can be connected to the forehead support 133 in a low-profile manner. Alternatively, mask 300 may also only have a pair of lateral headgear straps 154 as shown in mask 100 in which case headgear 150 may be used on mask 300 and forehead support 133 may not be present.
Full Face Mask
In a seventh embodiment, there is provided a full face mask 200 as shown in
Thermoformable hard seal 210 will extend out from the frame in the same manner in the nasal bridge and cheek regions and additional it will extend 20-40 mm from the frame in a lateral direction either side of the mouth and 20-50 mm in an inferior direction over the user's chin. In the chin region it may go under the chin to act as a chin support. The general contact area of the face may be similar to that of the full-face mask 30 face shield shown in
Frame 220 extends in an inferior direction relative to frame 120, of the nasal mask, to create a breathing chamber 228 that communicates with the users nose and mouth. Frame 220 also extends in a lateral direction to substantially cover the user's mouth, for example frame 220 should be between 40-80 mm wide in the region covering the user's mouth.
The outer perimeter of the seal 210, where it contacts the face, projected onto the coronal plane forms a full-face seal projected area. The outer perimeter of the frame 220, that defines the breathing chamber, excluding any tube connection 227 feature, projected onto the coronal plane forms a projected full-face frame area. The seal projected area of this full-face embodiment is approximately 50 cm2 and the projected area of the frame is approximately 20 cm2. The ratio of full-face seal area to frame area is approximately 2.5 or in the range of 2.0-3.0. A conventional CPAP full facemask has a projected seal area where it contacts the face of approximately 50 cm2 and a frame projected area, excluding the forehead support, of approximately 50 cm2. The ratio of seal to frame area is approximately 1.0. The seal/frame larger ratio may be possible as the seal is hard and does not need to be supported over a large area by a frame, leading to a more compact breathing chamber and mask.
The frame 220 may include an upper lip support 226 to act as a reference for fitting, alternatively it may include a cheek support or chin support region during the user thermoforming process.
The frame 220 may be formed in one or two components, as detailed in the nasal mask embodiment.
The full-face mask 200 may also have a non-rebreathing valve (NRV) to vent to atmosphere in the event of a pressure supply disruption.
The full-face mask frame 220 can also have upper and lower headgear connection points 224 to accommodate pairs of upper and lower lateral headgear straps. These may be located on the midline of the frame above and below the centre of seal area in the coronal plane. The headgear may have one or two pairs of lateral side straps. Given the mask is inherently stable it is possible to provide a full-face mask with only one pair of lateral side straps, connected to frame 220 near the centre of area of the full-face seal, that would be more minimal for the users.
The full-face mask 200 may be very low profile relative to conventional silicone full face mask and have the same stability and general benefits described in the nasal mask embodiment.
In another variation, the mask may take the form of a total face mask, such as the FitLife Total Face Mask from Philips. In this case the frame would be formed in a clear material to cover the user's mouth, nose and eyes. The thermoformable seal would extend from the frame to the face and seal on the user's forehead, side of the face and/or cheek and the chin. There may be an additional seal, passing over the user's nasal bridge and cheek region, to separate the nose and/or mouth breathing chamber from the chamber over the user's eyes. This will reduce fogging or condensation forming on the frame of mask in a region that may obscure the user's vision.
Nasal Pillow Mask
In an eighth embodiment, there is provided a nasal pillow mask configured to seal substantially under the nose, around the nares. It will be appreciated, by those skilled in the art, that the general description of the nasal mask embodiment design, function and benefits also apply to the nasal pillow mask embodiment.
An example of such as mask is he FPH Opus 360 nasal pillow mask details in '866. In this eighth embodiment, the silicone nasal pillows of '866 are replaced with a thermoformable hard material, as detailed in the nasal mask embodiment described herein. In this embodiment seal 110 would contact and form a seal around the user's nares. The thermoformable nasal pillow seal may from one seal around both nares, for example like the FPH Evora nasal mask or it may seal around and or in each nares like the Opus 360 nasal pillow mask. This embodiment may have a frame lip support to provide reference when thermoforming as described in the nasal mask embodiment. The seal of this embodiment will not extend over the user's nasal bridge region but it may extend over cheek region to stabilise the mask. The headgear designs of the nasal pillow mask embodiments of '866 may also be applied to the nasal pillow mask described herein, such as the headgear and curved elongate member, as the small nasal pillow mask may benefit from additional stability provided by these features.
It will result in a very low profile and stable mask that as the associated benefit described in the nasal mask embodiment, such as improving sealing performance, reducing pressure sores and preventing silicone allergies.
Other aspects of the nasal mask embodiment can be applied to this embodiment, such as the materials, crosslinking, tube connection, gas washout, headgear, sizing options and benefits etc.
Personal Protection Equipment Mask
In a ninth embodiment, there is provided a personal protection mask used in industrial and healthcare worker application applications, such as 3M Half Facepiece Respirator 7000 series. Personal protection masks are also used by the general public or healthcare workers to filter out city air pollution or air borne viruses in public and healthcare settings.
These masks may, or may not, be connected to a flow device but rely on the user to drive flow in an out the mask as they breath. They may have one, two or more openings in the form of frame inlet opening 121. For example, one may allow for air to enter the breathing chamber and another frame opening to allow exhaled air to exit the breathing chamber to the surrounding atmosphere, acting as an outlet opening. The frame inlet opening 121 may have a one-way valve to only allow air to pass into the breathing chamber and the outlet opening may have a one-way valve to only allow air to pass out of the breathing chamber. The inlet and outlet openings may also be connected to filters to clean the incoming and/or out-going air. The filters can be removed for replacement, cleaning or selecting different types of filters for specific applications, such as filtering bacterial, viruses, organic compounds, city air pollution or other industrial contaminants. The filtering of the outlet opening for aerosols, water droplets, bacterial and virus can protect others that may be nearby from bacterial and/or viral infections that the mask wearer may have, such as COVID-19.
They typically have a rigid frame, headgear and a rubber or silicone seal that engages the face. It will be appreciated by those skilled in the art that these flexible seals can be replaced with the hard thermoformable seal described herein and other aspects described may also apply such as the frame and headgear.
In addition, the mask may have a clear visor that extends up from the frame in a superior direction in order to cover the user's eyes to prevent the eyes being a pathway for infection. The visor may be part of the frame, that is formed as one unit during injection moulding, or it may be connected permanently or removably to the frame or other mask components, so the user can optionally use the visor when required.
In another variation, the visor may come into contact with the users face, around the eyes to seal the eyes from the environment. The face contacting region of the visor may additional have a foam seal or a hard thermoformable seal, as described in this specification.
In another variation, the mask may take the form of a total face mask, such as the FitLife Total Face Mask from Philips. In this case the frame would be formed in a clear material to cover the user's mouth, nose and eyes. The thermoformable seal would extend from the frame to the face and seal on the user's forehead, side of the face and chin. There may be an additional seal, passing over the user's nasal bridge and cheek region, to separate the nose and/or mouth breathing chamber from the chamber over the user's eyes. This will reduce fogging or condensation forming on the frame of mask in a region that may obscure the user's vision.
The same benefits also apply, for example a more compact lower profile mask with improved seal and comfort for the user. This will result in a mass manufactured, affordable, customisable personal protection mask.
Advantages
Selected advantages of the face shield, patient interface and methods and uses thereof may include:
The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.
Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as if individually set forth.
Aspects of the face shield, patient interface and methods and uses thereof have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 768130 | Sep 2020 | NZ | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NZ2021/050164 | 9/16/2021 | WO |
