Field of Invention

The present invention relates to a face mask primarily but not limited to medical use.

Background

The recent COVID-19 pandemic has profoundly changed daily lives of people around the world, and its effects will last long after the pandemic ends.

One effect is that many people may require a reliable respirator to safeguard themselves against contaminated air. There is a suite of protective devices to choose from: surgical masks to reduce the spread of infection, disposable N95 respirators and the more durable elastomeric respirators as well as Powered Air Purifying Respirators (PAPRs) for worker protection.

N95 respirators and surgical masks cost much less for an individual than PAPRs. However, they are not so economical if workers need to use them day after day during a pandemic, and people often cannot be fitted for surgical masks or N95 respirators due to facial hair or other reasons.

PAPRs have a lot of advantages such as allowing fit testing. Another advantage to using PAPRs is their reusability. PAPRs can be divided into the following groups: loose fitting PAPRs and tight fitting PAPRs. Existing loose fitting PAPRs include established PAPR models such as 3M™ Jupiter™, 3M™ Versaflo™ series and Bullard EVA, as shown in Figures la and lb. The loose fitting PAPRs provide constant air flow in a compact, streamlined form for added customer comfort. A recent tight fitting PAPR is CleanSpace® Respirator (see Figure 2). The mask of the tight fitting PAPRs must be individually fitted. A motor and filter are located in the neck ring, and a head harness and neck support clip are also required. Multiple sources have also adapted snorkel masks for use as personal protective equipment (PPE) (Figure 3) or for non-invasive ventilation (NIV) (Figure 4) of patients.

The PAPRs still have some key disadvantages. The major disadvantages are maintenance and cost. Challenges to using PAPRs also include a relatively short battery life, difficulties in hearing due to the noise of the blower, and to a lesser extent, difficulties in seeing due to the hood. Existing PAPRs cannot be used for both non-invasive ventilation in patients and for healthcare providers.

It would be desirable to address or alleviate at least one of the above difficulties.

Summary

Disclosed herein is a face mask comprising a window cover configured to cover at least the mouth and nose of a person when the mask is fitted, whereby the window cover comprises of an engaging member extending from the window cover and about the head of the person to at least partially seal the mask to a head of the person; at least one port projecting outwardly from the window cover; and a fastening mechanism for securing the engaging member to the person, the fastening mechanism being capable of connecting to a pressure indicator adapted to measure a fitting pressure when the fastening mechanism secures the engaging member to the person, wherein the fitting pressure can be varied according to the application of the mask.

As used herein, the term "about the head" may be used to refer to 'around the head', 'around a portion of the head" - e.g. around the face, and other similar meanings and enabled by context. The mask may include an inner skirt that sits inside the engaging member to substantially seal the mask to the head of the person. The skirt may include resilient material that resiliently conforms to contours of the head of the person under resilient bias provided by the fastening mechanism when the mask is fitted to the person.

The fastening mechanism may include a belt coupled between spaced apart sections of the engaging member. The belt resiliently may stretch around the head of the person when the mask is fitted. The spaced apart sections may be located at forehead and chin engaging sections of the engaging member. The belt may be formed in two sections. Each section of the belt may be coupled between the forehead engaging section of the engaging member and respective spaced apart chin engaging sections of the engaging member. The belt may have a "V" or a "Y" shape. The "V" or "Y" shape may be inverted such that the opposite or divergent arms of the "V" or "Y" extend around opposite sides of the neck.

The port may be shaped to at least partially receive a nose of the person therein when the mask is fitted to the person.

The fitting pressure may have a value (i.e. a pressure level) suitable for the mask to be used as part of a powered air-purifying respirator (PAPR) which is used by a medical worker, wherein the fitting pressure ensures that there are some gaps between the mask and the face of the medical worker, so that the PAPR enables air flow into the mask via the port and the air inside the mask to be discharged through the gaps, thereby creating a positive pressure inside the mask. To this end, the fitting pressure is sufficient to prevent air from entering the mask from the surrounding environment, between the face and engaging member, but is low enough that air within the mask, that is under positive pressure from one or both of a pump of the PAPR and exhalation from the user, can be pushed out between the engaging member and face (e.g. the positive pressure creates the gaps referred to above while pressure is positive, but that the gaps are only present when pressure in the mask is positive as the engaging member resiles back against the face, closing the gaps, when positive pressure is no longer present in the mask).

The mask may further comprise a filtration mechanism at the port to filter particulates from air flowing into the mask.

The mask may comprise a motor or electrical fan coupled to the port.

The mask may include a mount for an audio module.

The window cover may comprise a viewing window, which is shaped so that the viewing window is spaced from a face of the person by a distance sufficient to accommodate spectacles worn by the person. Said distance may be sufficient to accommodate the person wearing a N95 mask.

The fitting pressure may be sufficient to prevent ingress and egress of air between the engaging member and head when the mask is used by a patient.

A ventilation system may be coupled to the mask. The ventilation system may comprise: a positive airway passage (PAP) module for breathing support; an O ₂ supply; a check valve for controlling the passage of the air; a first head and moisture exchanger (HME) filter for humidifying and filtering the air; an O ₂ inlet for letting O ₂ to enter from the O ₂ supply; an air hose for conveying the air; a second HME filter for humidifying and filtering the air whereby the HME filter is coupled to the port of the face mask; a T-joint for connecting the air hose, HME filter and a positive end expiratory pressure (PEEP) Valve; and the PEEP Valve for discharging out the air inside the mask. Description of Figures

Embodiments of the present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figures la and lb are images of a loose fitting prior art powered air purifying respirator system;

Figure 2 is an image of a tight fitting prior art powered air purifying respirator system;

Figures 3 and 4 are images of another prior art powered air purifying respirator system;

Figure 5 is a front view of a face mask without a ventilation system or a powered air purifying respirator system (PAPR);

Figure 6a is a side view of the mask shown in Figure 5 coupled to a powered air purifying respirator system;

Figure 6b is an image of a medical worker putting on the face mask shown in Figure 5, the mask being coupled to a powered air purifying respirator system;

Figure 7 is a front view of the mask shown in Figure 5 coupled to a ventilation system used by a patient;

Figures 8a and 8b are images of component parts of a BiPAP system used with the face mask shown in Figure 5;

Figure 9 is an image of a side view of a person wearing the face mask shown in Figure 5;

Figures 10a to 10c are images of exemplary embodiments of the 02 supply; Figure 11 is an image of component parts of a backup power supply; and Figure 12 is a collection of images showing sore marks on faces after existing prior art mask use.

Detailed Description

Described herein are masks versatile in their application that can be used as a powered air-purifying respiratory (PAPR) or non-invasive ventilation (NIV) masks. Compared with the conventional snorkel mask, proposed masks are superior by being light weight for use in clinical environments. Some masks disclosed herein are able to attach to, or include, a motor fan and high-efficiency particulate air (HEPA) filter to effect filtration. Proposed masks are also able to offer cartridges for particulate and/or gas/vapor protection by adding additional mechanisms. Embodiments of the disclosed design provide enhanced performance by making it easier for the user to breathe, and also provide a positive pressure so that any leaks will not lead to influx of contaminated air. Embodiments of such masks have sufficient space to fit over additional layers of protection such as spectacles as well as an N95 mask to allow for the user's comfort and safety. The components of the disclosed mask can be cleaned, disinfected, re-used, and shared.

As particularly shown in Figure 5, the mask (10) comprises a window cover (14). In one embodiment, the window cover 14 comprises or is a generally planar viewing window. The planar viewing window may have tapered sides as shown in Figure 6a, to allow peripheral viewing while maintaining a planar forward facing window to avoid distortion of the forward view. In another example, the window cover 14 comprises or is a spherical or rounded viewing window that provides larger space than a planar viewing window. Said spherical or rounded window uses a curved lens that extends beyond the wearer's vision line (e.g. limit of peripheral vision), giving the wearer a full range of vision. The window cover 14 may be made from transparent materials, such as glass and/or plastic (but not limited to both). By still covering a face (16), the mask 10 with the transparent window cover 14 creates a physical barrier from particles while still allowing people to read lips and facial expressions.

The window cover 14 is arranged to extend at least partially over the face 16 of a person (18) when the mask 10 is fitted (Figure 6a). The window cover 14 may be configured to cover at least the mouth and nose of the person 18 when the mask is fitted. It will be appreciated that the mask 10 may be a half face mask which covers only the mouse and/or nose of the person - this is acceptable where a separate face mask is used to cover the eyes or portion of the face not covered by the mask 10, or in environments where pathogens are unable to via the skin or eyes. Alternatively, the mask 10 may be a full face mask which covers the entire face 16, including the eyes, mouth and nose of the person 18. One advantage of a full face mask is that it is comfortable to wear over long periods. The full face mask enables the wearer to take a full breath of air and exhale it naturally. Said full face mask also offers better fitting and sealing as it seals around the whole face rather than just around the nose and mouth. With the full face mask, the edges of the mask can be completely sealed. This can result in the eyes, nose and mouth being entirely within the peripheral edge (engaging member) of the mask. Such design enables the mask 10 to move with the wearer's face, which prevents contaminated air from slipping in. Since it covers the eyes and face, the full face mask also protects against liquid splashes and irritating vapours.

The full-face mask 10 is a step above modification of existing commercial masks, and allows for a range of applications. Current masks have problems fitting patients with hollow cheeks. Figure 12 shows score marks on existing faces after existing prior art mask uses. Current masks have problems fitting patients with hollow cheeks, missing tooth or teeth, and loose skin. This is because they are a one-size fits all, or many, design. In contrast, embodiments of the present mask can have the fitting pressure varied according to the application of the mask - e.g. tighter fit where venting between the face and engaging member is undesirable, and looser fit where air should be able to exit (but not enter) the mask between the engaging member and face. The fitting pressure can also be varied so that the mask can be fitted onto the face of the wearer so that it is more comfortable to wear over long periods. As such, the present mask has better fitting and sealing for a wearer, regardless of the shape of the cheeks of the wearer and the condition of their teeth and skin. The window cover 14 comprises an engaging member (20) extending from the window cover 14 to at least partially seal the mask 10 and to engage (i.e. position) the window cover 14 over the face 16 of the person 18. In particular, the engaging member 20 may engage about the head of the person 18 to at least partially seal the mask to the head of the person 18. It will be appreciated that the term "about the head" and similar, when used with reference to the engaging member, means the engaging member can be embodied by a fastening mechanism that goes over the head, passes under the chin, around the head, over the ear and so on, and any combination thereof. It will also be appreciated that the term "at least partially seal", can include a full seal whereby air cannot enter or exit the mask between the engaging member and face of the wearer, and embodiments where air can escape the mask between the engaging member and face - e.g. through gaps that are created by positive pressure within the mask.

In one embodiment as illustrated in Figure 5, the engaging member 20 comprises a forehead engaging section (20a) and a chin engaging section (20b). In particular, to seal the mask 10 to the head of the person 18, the forehead engaging section 20a is shaped to engage over the forehead (22) of the person 18, and the chin engaging section 20b is shaped to engage under the chin (24) of the person 18 (Figure 7). In another embodiment (not shown), the engaging member 20 comprises an ear engaging section and a neck engaging section. To seal the mask 10 to the head of the person 18, the ear engaging section is adapted to engage over ears of the person 18, and the neck engaging section is adapted to engage around the neck of the person 18.

The mask 10 shown in Figures 5 and 7 also comprises at least one port (28) projecting outwardly from the window cover 14. In particular, the port 28 is arranged to overlie the person's mouth and/or nose when the mask 10 is fitted. Accordingly, the port 28 is shaped to at least partially receive the nose and/or mouth of the person 18 therein when the mask is fitted to the person. The port 28 may interface with a PAP module 36 (see Figure 8a) to provide air flow to the mask 10 through the port 28. Said PAP module 36 uses a machine to pump air under pressure into the air flow of the lungs, and is a generic term applied to sleep device that provide positive airway pressure (PAP) - e.g. for apnoea treatment. The PAP module normally comprises a portable machine that blows pressurized room air through a tube connected to the port 28. This positive airflow helps keep air flow open, preventing the collapse (e.g. airway collapse) that occurs during apnoea, thus allowing normal breathing. In one embodiment, the port 28 is adapted to interface with a Bilevel PAP (BiPAP) module shown in Figure 8 or, in other embodiments, a continuous PAP (CPAP) module. It will be appreciated that both BiPAP and CPAP modules can be applied to sleep apnoea treatment simultaneously as they both have their own advantages. CPAP machines have an adjustable pressure setting regardless of whether the person 18 is inhaling or exhaling, and is generally recommended for obstructive sleep apnoea. BiPAP modules have different pressure settings, allowing for lower pressure level during exhalation, and are used to treat disorders that require structured airway support.

The mask 10 further comprises a fastening mechanism (40) for securing the engaging member 20 to the person 18. Said fastening mechanism may be arranged to go over the head, pass under the chin, around the head, over the ear and so on. The fastening mechanism holds the engaging member against the head of the mask wearer. Due to resilience in one or both of the engaging member (e.g. by providing a flexible rubber seal as, or in, the engaging member, when compared with the alternative stiff rubber or plastic seal) and fastening mechanism (e.g. an elastic belt or band versus a fixed length belt), the fastening mechanism may fasten the engaging member 20 in a resilient manner to the wearer. In particular, the engaging member 20 may include resilient material that resiliently conforms to contours of the person's (i.e. wearer's) head under resilient bias provided by the fastening system 40 when the mask 10 is fitted to the person 18. In some embodiments, the mask comprises easy release clips situated on the front of the mask for minimizing self-contamination which may happen when users reaches behind their head to release the mask. Each clip may be a known clip and may hold one or more ends of the fastening mechanism in register with the engaging member or window cover, and be releasable to release that end from the engaging member or window cover in a known manner.

When the mask 10 is fitted with the PAP module 36, such as the BiPAP module shown in Figure 8, the engaging member 20 maintains a positive air pressure within the mask 10 when compared to the external environment so as to inhibit ingress of external contaminants into the mask 10. The engaging member 20 bleeds out air supplied from the PAP module 36 (e.g. between the engaging member and face of wearer) so as to maintain a constant air pressure within the mask 10. As will be discussed in more detail, the fastening mechanism 40 is capable of connecting to a pressure indicator adapted to measure a fitting pressure when the fastening mechanism 40 secures the engaging member 20 to the person 18. In particular, the pressure indicator is adapted to measure the fitting pressure when the fastening mechanism 40 secures the engaging member 20 to the person 18. The pressure indicator may be connected to the fastening mechanism 40. To determine the fitting pressure of the mask 10, a pressure indicator may be incorporated into the fastening mechanism 40 - e.g. a strain gauge (or similarly a piezoelectric pressure sensor) may be incorporated into the fastening mechanism such that tightening or loosening of the fastening mechanism result in increased or reduced strain (force), respectively, on the strain gauge (piezoelectric pressure sensor) a signal from which is then made known to the wearer via an indicator to indicate the desired fitting pressure has been reached (e.g. via an LED that flashes from a brief period in the mask to indicate that the desired fitting pressure has been reached, via audible alarm in a speaker or headset incorporated into the mask as discussed herein, or via another mechanism). A further signal may be provided by the strain gauge (piezoelectric pressure sensor) to the wearer when the pressure is too great - e.g. a first signal may identify that a lower fitting pressure threshold has been reached and a second signal may identify that an upper fitting pressure threshold has been reached, a desired fitting pressure range being between the lower and upper thresholds. In one embodiment, the fastening mechanism 40 is a strap that passes around the head of the wearer to hold the mask against the wearer's face. In such case, the strain gauge would indirectly measure the fitting pressure of the engaging member against the face. It will be appreciated that there will also be more direct measurements achievable using the pressure indicator (e.g. a strain gauge or piezoelectric pressure sensor) incorporated into the engaging member itself. The fitting pressure should have a value suitable for application of the mask 10 being used by the person 18. In one embodiment, the fitting pressure enables a tight fitting of the mask 10 with band tension on the person 18 so as to prevent any leakage from the mask 10. It will be appreciated that the fitting pressure can be varied according to the application of the mask 10.

The mask 10 may include an inner skirt (38) shown in Figures 5, 6a and 7 that sits inside the engaging member to substantially seal the mask 10 to the head of the person 18. The term "substantially seal" here refers to a seal being sufficient for safe use of the mask 10 for the intended purpose of use of the mask 10. The inner skirt 38 may include resilient material that resiliently conforms to contours of the head of the person 18 under resilient bias provided by the fastening mechanism 40 when the mask 10 is fitted to the person 18. With little or no pressure, the natural resiliency of an engaging member form from an elastomer compound, provides the seal. When the mask 10 is equipped with the PAP module 36 shown in Figure 8, compared with the external environment, the inner skirt maintains a positive air pressure inside the mask 10, thereby preventing external contaminants from entering the mask 10. In one embodiment, the inner skirt 38 is silicone, which is a good substance to use for seals. Silicon skirts are commonly used to bind surfaces such as plastic, metal, and glass together. A silicon seal provides moulding to a wide range of facial features, hence is able to cater to different sized window covers for users of types of spectacles. In another embodiment, the inner skirt is a rubber seal for preventing external contaminants from entering the mask 10 by closing the spaces/gaps between the face 16 of the person 18 and the engaging member 20. An O-ring seal consisting of a donut-shaped ring with a circular cross section may also be used to create a barrier to potential airflow leakage paths between the face 16 and engaging member 20. Said O-rings can seal the mask 10 to the head of the person 18 by mechanical deformation when sitting inside the engaging member 20.

Shown in Figure 6a and 7, the fastening mechanism 40 may be a belt coupled between the spaced apart sections 20a and 20b of the engaging member. The belt 40 may include resilient material that resiliently conforms to contours of the head of the person 18. In one embodiment, said resiliently belt 40 stretches around the head when the mask 10 is fitted. In other examples, the belt 40 may be arranged to go over the head, pass under the chin, over the ear and so on.

The belt may be formed in different sections. In one embodiment shown in Figure 6a, the belt 40 comprises two separate sections (40a) and (40b). It will be appreciated that the spaced apart sections (for example 20a and 20b in Figures 5 and 6a) are preferably located at different locations of the engaging member 20, and each section of the belt 40 needs to be coupled between respective sections of the engaging member 20 for securing the engaging member 20 to the person 18. In one embodiment, the chin engaging section 20b is shaped to engage under the chin 24 of the engaging member, and the forehead engaging section 20a is shaped to engage over the forehead 22 of the person 18. Accordingly, for securing the engaging member 20, each section of the belt 40 (i.e., sections 40a and 40b on respectively opposite sides of the head and mask) is coupled between the forehead engaging section 20a of the engaging member and spaced apart chin engaging section 20b (on respectively opposite sides of the head and mask) of the engaging member 20, respectively. In another embodiment, the spaced apart sections 20a and 20b are located near ear and neck engaging sections of the engaging member, respectively. In this case, each section of the belt 40 is coupled between the ear engaging section of the engaging member and respective spaced apart neck engaging sections of the engaging member for securing the engaging member 20.

The belt 40 is advantageously "V" shaped or "Y" shaped. It will be appreciated that an inverted "V" or "Y" shape may also be considered. Said "V" shaped and "Y" shaped belts are often used to solve slippage and alignment problems. The "V" shaped or "Y" shaped belts may be homogeneously rubber or polymer throughout, or there may be fibres embedded in the rubber or polymer for strength and reinforcement.

In one embodiment, the mask 10 is used as one part of a PAPR (powered air purifying respirator), which refers to a type of respirator used to safeguard workers against contaminated air. A PAPR consists of a headgear-and-fan assembly that takes ambient air contaminated with one or more types of pollution or pathogen, and can be used to actively remove a sufficient proportion of the hazards, and then deliver the clean air to the user's face or mouth and nose. Said PAPR is often used by medical workers. It will be appreciated that PAPRs are positive-pressure respirators that need to maintain a positive pressure in the face-piece (i.e. within the window cover) during both inhalation and exhalation. The fitting pressure of the mask 10 needs to have a value suitable for application of the mask 10 being used as part of, or as, the PAPR. In particular, the fitting pressure of the mask 10 should ensure that there are some gaps between the mask 10 and the face of the person 18, so that the PAPR enables air flow into the mask 10 via an air inlet (for example the port 28) and the air inside the mask 10 being discharged from the sides of the mask 10 and through the gaps, thereby creating a positive pressure inside the mask 10. The gaps may be transient such that they are present when pressure within the mask is sufficiently greater than that outside the mask, such that air can exit the mask between the engaging member and face. But, when the pressure within the mask is close to ambient pressure then the engaging member resiles (i.e. relaxes) back against the face, thereby closing the gaps.

When the mask 10 is used as one part of the PAPR, it can be important for some applications to ensure that the fitting pressure of the mask 10 enables a tight fitting of the PAPR so as to prevent any leakage from the PAPR. In general, the fitting pressure needs to be sufficient to prevent ingress and egress of air between the engaging member and head. Accordingly the mask 10 needs to provide a positive pressure so that any leaks will not lead to influx of contaminated air. In one example shown in Figure 6a, the fitting pressure is larger than or equal to a minimum pressure that is sufficient to preclude ingress of air between the engaging member 20 and the head of the person 18, but to permit egress of air from within the mask 10 to atmosphere, between the engaging member and face. It will be appreciated that unlike the negative-pressure respirators such as N95 masks, the proposed positive-pressure mask 10 has the advantage of eliminating breathing resistance.

The mask 10 makes it usable by patients who are medically disqualified from negative-pressure respirators such as N95 masks because the proposed mask 10 has a higher assigned protection factors. Shown in Figure 6a and 6b, the mask 10 comprises a filtration mechanism (50), which is used for delivery to the user for breathing.

Said filtration mechanism may be attached, integral or otherwise positioned at the port 28 to filter particulates from air flowing into and out of the mask 10. In some embodiments, the 3D printed adaptors (not shown) are attached to the front of the mask. It will be appreciated that the filtration mechanism 50 may be attached via the 3D printed adaptors to the front of the mask 10. The mask 10 may shield the person 18 from droplets and have a filtration efficiency selected for the intended use of filtration mechanism 50. For example, the mask 10 may be outfitted with the filtration mechanism 50 for atmospheres with particulate contamination, with a chemical cartridge for atmospheres with toxic gases or vapours, or both in combination. In other embodiments, the filtration mechanism 50 is designed to remove fine particulate matter from wood materials, or from working with mineral-based materials. The mask 10 is able to add on a HEPA filter (52) to effect filtration. When used with the HEPA filter, airborne particles containing small pathogens (viruses, bacteria) can be removed by the mask 10. It will be appreciated that the type of the filtration mechanism 50 incorporated into the mask 10 should be appropriate to the contaminants that need to be removed.

In one embodiment shown in Figures 6a, the mask 10 is able to add on a motor or electrical fan (54) to further effect filtration. The motor or electrical fan 54 may be coupled to the port of the mask 10 for forcing incoming air into the mask 10. The mask 10 with the motor or electrical fan 54 has the advantage of eliminating breathing resistance caused by unpowered respirators such as N95 masks. The mask 10 may comprise a battery or other power source for operating the motor or electrical fan 54. Said motor or electrical fan 54 can be swapped when its battery is low. Such design prevents the user from removing the mask 10 entirely, thus enabling extended use of the mask 10. In one embodiment shown in Figure

11, a backup power supply 110 may be provided, in case of any power failure. It will be appreciated that in some cases there is no need for dedicated and expensive battery charging docks, as charging the motor 54 may be done using a standard micro USB charging point located on the motor or electrical fan 54. The mask 10 may include a mount for an audio module 46 (see Figures 5 and 6a). Said audio module 46 allows for better communication, which is a limitation of the existing PAPR. The audio module here may be a small electric device used to transmit and/or receive audio signals between the user of the mask 10 and the others. The user may communicate with the others wirelessly. This wireless communication may be accomplished through optical communication or through radio-frequency (RF) communication. For example, the audio module 46 may be a RF module complying with a defined protocol for RF communications such as Zigbee, Bluetooth, or Wi-Fi, or it may implement a proprietary protocol. The audio module 46 may also comprise a microphone for increasing the volume of the wearer of the mask 10, and a headset (e.g. a wireless headset - this may run off the same power supply as the motor in relevant embodiments) for communicating with others in a noisy environment. In one embodiment, it is desirable to enable healthcare workers to wear the mask 10 with the audio module 46 throughout their interactions with patients. In another embodiment, a fireman can use the audio module 46 to contact other firemen in smoky places.

The application of the mask 10 in the present disclosure are particularly useful for BiPAP systems and PAPR systems, although other applications are possible as well. It will be appreciated that the fitting pressure of the mask 10 may have different values set for different applications. In one embodiment, when the fitting pressure has a first value, the mask 10 is suitable for an application for a BiPAP system, whereby a ventilation system may be coupled to the mask 10. When the fitting pressure has a second value, the mask 10 is then suitable for an application for a PAPR system, whereby the filtration system 50, motor fan 54 and audio module 46 are coupled to the mask 10. It will also be appreciated that reference to a "value", or similar, of fitting pressure may be substituted for reference to a fitting pressure "range" unless context dictates otherwise. Shown in Figures 6A and 9, the mask 10 may comprise a viewing window, which is shaped so that the viewing window is spaced from the face 16 of the person 18 by a distance sufficient to accommodate spectacles worn by the person. In one embodiment, the mask 10 can be widened for accommodating spectacles. Said distance may also be sufficient to accommodate the person 18 wearing an additional mask (see Figure 9). In some clinical scenarios the person 18 may wear an additional N95 mask. In one embodiment, the depth of the mask 10 can be increased for accommodating N95 mask and/or large nose of the person 18. The mask 10 that can fit over spectacles and N95 mask is able to allow for user comfort and safety. Such designs also have advantages in terms of ergonomic impacts. The viewing window can have different shapes. In one embodiment, the viewing window is generally planar. The generally planar viewing window is preferably made from a polycarbonate and serves as a field of view for the person 18. In another embodiment, the viewing window is spherical. It will be appreciated that such a spherical viewing window may provide larger space than a planar viewing window. Compared with the planar viewing window, the spherical viewing window is more likely not to restrict peripheral vision. The spherical window may further comprise a curved lens that extends beyond the line of sight of the person 18, thereby providing the person 18 with a complete field of view (FOV). Said FOV refers to the extent of the observable world that can be seen by the person 18.

The mask 10 can be further coupled with a ventilation system 56 (see Figure 7) for patients with respiratory difficulties. In one embodiment, the mask 10 which is coupled with the ventilation system is used by a patient. Said ventilation system is used to supply oxygen for patients with respiratory issues. The ventilation system 56 may be coupled to the mask 10 at the port 28. It will be appreciated that the present invention also relates to an apparatus 74 (see Figures 8a and 8b) suitable for patients with respiratory difficulties. The apparatus 74 comprises at least one of the mask 10 and the ventilation system 56.

In one embodiment shown in Figures 8a and 8b, the ventilation system 56 comprises, but is not limited, to the following components: i) the PAP module 36 for breathing support; ii) an O2 supply (58); iii) a check valve (60) for controlling the passage of the air; iv) a first heat and moisture exchanger (HME) filter (62) for humidifying and filtering the air; v) an O2 inlet (64) for letting O2 to enter from the O2 supply 58; vi) an air hose (66) for conveying the air; vi) a second HME filter (68) for humidifying and filtering the air whereby the second HME filter 68 is coupled to the port of the mask 10; vii) A T-joint 70 for connecting the air hose 66, HME filter 68 and a positive end-expiratory pressure (PEEP) Valve 72; and viii) The PEEP Valve 72 for discharging out the air inside the mask 10.

The PAP module 36 may be a BiPAP module or a CPAP module or any other suitable PAP module. When the mask is fitted with the PAP module, the head engaging member maintains positive air pressure within the mask when compared to the external environment so as to inhibit ingress of external contaminants into the mask. In the example shown in Figure 8a, the module 36 is a BiPAP machine for breathing support. Said BiPAP machine may be Philips A30 or Yuwell YH830 or any other suitable brand. As shown in Figure 8b, the BiPAP machine may have different pressure settings, allowing for lower pressure level during exhalation and higher pressure level during inhalation, and can be used to treat disorders that require structured airway support. The O2 supply 58 may be an O2 concentrator, which refers to a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched product gas stream. The O2 concentrator normally uses pressure swing adsorption technology that is widely used for oxygen provision in healthcare applications, especially where liquid or pressurized oxygen is too dangerous or inconvenient, such as in homes or portable clinics. Some example embodiments of the O2 supply 58 are shown in Figure 10. The O2 supply may be Philips EverfloC Concentrator (5 LPM) or Yuwell9F-5AW (5 LPM) or NidekNuvolO (10 LPM) or any other suitable brand.

The check valve 60 is a device or machine that allows the O2 fluid to flow through it in only one direction. As shown in Figure 8b, when the wearer of the mask 10 is inhaling, the O2 fluid through the check valve 60 is only allowed to flow from the PAP module 36, the HME filters 62 and 68, the air inlet 64, and the air hose 66 to the mask 10. When the wearer is exhaling, the exhaled air is not allowed to flow though the check valve to the PAP module 36. As a result, the exhaled air will be drawn to the PEEP valve for discharge. PEEP here refers to the pressure in the lungs above atmosphere pressure that exists at the end of expiration. It prevents ventilator induced lung injury - the loss of lung units taking part in gas exchange as a result of collapse at end-expiration impairs O2 intake or absorption in the lungs. A PEEP valve is a spring loaded valve that the wearer of the mask 10 exhales against.

The above mask configurations provide for flexibility in the configuration of the face of the wearer, usage of spectacles and additional masks within the masks described herein, without loss of function. Also, or in other embodiments, the masks are adaptable for use with respiratory equipment such as PAP, PAPR, CPAP and BiPAP systems, to control the atmosphere composition (e.g. oxygen level) within the mask, and to facilitate comfortable wearing of the mask and respiration. It will be appreciated that many further modifications and permutations of various aspects of the described embodiments are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.