U.S. patent application number 12/443415 was filed with the patent office on 2010-02-25 for respirator mask.
This patent application is currently assigned to AUSTRALIAN CENTRE FOR ADVANCED MEDICAL TECHNOLOGY PTY LTD. Invention is credited to Peter Spencer, Colin Sullivan.
Application Number | 20100043798 12/443415 |
Document ID | / |
Family ID | 39229649 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100043798 |
Kind Code |
A1 |
Sullivan; Colin ; et
al. |
February 25, 2010 |
RESPIRATOR MASK
Abstract
A mask for supplying gas under pressure to an airway of a human
including: a flexible manifold shell, being made of a flexible
material, the manifold including means for connection to a gas
delivery pipe. There are at least two side walls which are at least
partially formed by portions of the manifold shell; a flexible face
contacting element defining an orifice to accommodate the nose of
the human; a first connecting strap having a first end connected to
the mask and a second end connectable to a mask retaining strap;
and a second connecting strap having a first end connected to the
mask and a second end connectable to the mask retaining strap. The
first strap and the second strap engage respective side walls of
the mask for distributing opposing distortional forces to a
substantial portion of the respective side walls when the mask is
in use. The connection of the straps to the mask allow forces
exerted by the first and second straps are capable of deforming the
manifold at least along X and Y axes to create a variety of
different mask/orifice shapes. The manifold of the mask has a
manifold height and a centroid. The first and second straps engage
the mask along a connecting length thereby joining the first and
second straps to respective side walls of the mask so that an axis
through the centroid normal to the Y axis, intersects with at least
part of each strap.
Inventors: |
Sullivan; Colin; (Balmain,
AU) ; Spencer; Peter; (Balmain, AU) |
Correspondence
Address: |
LANDO & ANASTASI, LLP
ONE MAIN STREET, SUITE 1100
CAMBRIDGE
MA
02142
US
|
Assignee: |
AUSTRALIAN CENTRE FOR ADVANCED
MEDICAL TECHNOLOGY PTY LTD
Balmain, NSW
AU
|
Family ID: |
39229649 |
Appl. No.: |
12/443415 |
Filed: |
September 28, 2007 |
PCT Filed: |
September 28, 2007 |
PCT NO: |
PCT/AU2007/001455 |
371 Date: |
October 29, 2009 |
Current U.S.
Class: |
128/205.25 |
Current CPC
Class: |
A61M 16/0683 20130101;
A61M 16/0057 20130101; A61M 16/0616 20140204; A61M 16/06 20130101;
A61M 16/0633 20140204 |
Class at
Publication: |
128/205.25 |
International
Class: |
A61M 16/06 20060101
A61M016/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2006 |
AU |
2006905360 |
Claims
1. A mask for supplying gas under pressure to an airway of a human
including: a flexible manifold shell, being made of a flexible
material, the manifold including means for connection to a gas
delivery pipe, at least two side walls which are at least partially
formed by portions of the manifold shell; a flexible face
contacting element defining an orifice to accommodate the nose of
the human; a first connecting strap having a first end connected to
the mask and a second end connectable to a mask retaining strap; a
second connecting strap having a first end connected to the mask
and a second end connectable to the mask retaining strap; wherein,
the first strap and the second strap engage respective side walls
of the mask for distributing opposing distortional forces to a
substantial portion of the respective side walls when the mask is
in use; wherein the connection of the straps to the mask allow
forces exerted by the first and second straps are capable of
deforming the manifold at least along X and Y axes to create a
variety of different mask/orifice shapes; wherein, the manifold of
the mask has a manifold height and a centroid; and wherein the
first and second straps engage the mask along a connecting length
thereby joining the first and second straps to respective side
walls of the mask so that an axis through the centroid normal to
the Y axis, intersects with at least part of each strap.
2. A mask according to claim 1 wherein the first end of each strap
connects to a wall of the mask via webs which form the first
end.
3. A mask according to claim 2 wherein the webs connected to the
manifold along opposing sidewalls.
4. A mask according to claim 3 wherein the webs are integral with
the walls of the manifold and when transmitting load to the mask,
are capable of inducing distortion in the mask along the X, Y and Z
axes while a seal is maintained between the mask and a users
face.
5. A mask according to claim 4 wherein the length of the contact
between each of the webs of the respective first and second straps
is greater than the width of each said first and second straps.
6. A mask according to claim 5 wherein, the face contacting element
maintains a seal between the mask and the face of a wearer
irrespective of induced movement of the mask in either the X, Y or
Z directions, when a load is applied by the straps on the mask.
7. A mask according to claim 6 wherein a ratio of the manifold
height to the distance of the connecting length of the webs to the
mask falls within the range 0.8-2.0.
8. A mask according to claim 7 wherein a ratio of the contact
length of the web at the wall of the manifold to the length of the
manifold wall falls within the range 0.3-1.0.
9. A mask according to claim 8 wherein the webs each have an
oblique angled edge the same an oblique angled wall of the manifold
and which forms the contact length between each web and the
manifold.
10. A mask according to claim 9 wherein the webs contact the
manifold wall at an interface between the manifold and the face
contacting part.
11. A mask according to claim 10 wherein the height of the manifold
is measured from a lowermost wall of the manifold to an uppermost
wall or apex of the manifold at a point which engages a nose bridge
of a user.
12. A mask according to claim 11 wherein, the face contacting part
has a flexible membrane allowing X, Y or Z axis movement of the
mask.
13. A mask according to claim 12 wherein the membrane to deforms or
displaces in a rolling motion to retain a gas seal against the face
of a wearer.
14. A mask according to claim 13 wherein a resultant force
generated by loadings applied by the straps is applied at a
location generally in the middle third of the height of the
manifold so that the load is applied above the neutral axis of the
manifold.
15. A mask according to claim 14 wherein, the higher the ratio
between the web contact length and the length of the manifold wall,
the higher above a neutral axis through the centroid a resultant
force transmitted to the mask will be applied.
16. A mask according to claim 15 wherein, the manifold shell has an
average wall thickness within the range of 1 mm-2.5 mm.
17. A mask according to claim 16 wherein, the flexible face
contacting portion has as average wall thickness within the range
of 0.3 mm to 0.7 mm.
18. A mask according to claim 17 wherein, the manifold includes a
third strap for anchoring the mask.
19.-46. (canceled)
47. A mask for supplying gas under pressure to an airway of a human
including: a flexible manifold shell, being made of a flexible
material, the manifold including means for connection to a gas
delivery pipe, at least two side walls which are at least partially
comprised of portions of the manifold shell; a first mask shape
forming element for distributing distortional forces to a
substantial portion of one side wall that attaches to or is
integral with a significant portion of that one side wall of the
mask; and a second mask shape forming element for distributing
distortional forces to a substantial portion of an other side wall
that attaches to or is integral with a significant portion of that
other side wall of the mask, each mask shape forming element being
connected to, or being connectable to, a strap; a flexible face
contacting element defining a recess to accommodate the nose of the
human; wherein, forces exerted by the first and second mask shape
forming elements are, capable of deforming the flexible face
forming element and manifold in the X-Y plane to create a variety
of different mask/orifice shapes and attitudes.
48.-53. (canceled)
54. A mask for supplying gas under pressure to an airway of a human
including: a flexible manifold shell made of a flexible material,
the manifold including means for connection to a gas delivery pipe,
at least two side walls which at least partially comprise portions
of the manifold shell; a first mask shape forming element for
distributing distortional forces to a substantial portion of one
side wall that attaches to or is integral with a significant
portion of that one side wall of the mask; and a second mask shape
forming element for distributing distortional forces to a
substantial portion of another side wall that attaches to or is
integral with a significant portion of that other side wall of the
mask, each mask shape forming element comprising a generally
triangular shaped web one side of which engages the manifold wall
and being connected to, or being connectable to, a strap; a
flexible face contacting element defining an orifice to accommodate
the nose of the human; wherein forces exerted by the first and
second mask shape forming elements are, capable of deforming the
flexible face forming element and manifold in the X and Y planes to
create a variety of different mask/orifice shapes; characterised in
that the manifold of the mask is defined by; a manifold height
extending along a Y axis; and the shape forming elements define a
connecting length joining the respective first and second shape
forming elements to each wall; wherein a ratio of height of the
manifold to connecting length falls within the range 0.8-2.0;
wherein a resultant force applied from distribution of load
thorough said web over a predetermined length of web or over a span
of point loads applied to the web lies approximately in a middle
third of the manifold height to allow the mask to accommodate
distortion from such applied load.
55.-59. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to a mask, in particular to a mask
for supplying gases, typically air or oxygen, to the airways (nose
or no and mouth) of humans. Such masks are often referred to as
"respirator masks". Such masks are particularly suited to applying
continuous positive airway pressure (CPA) to patients for treatment
of sleep apnoea, however the invention is not in any way limited to
masks for that use only. More particularly the invention relates to
a face mask including straps which terminate in webs which engage
opposing walls of the mask and which have a contact length which
transfers in use loadings applied to the straps through to the mask
allowing the mask to displace on a users face in an X, Y or Z
direction and without breaking a seal created between a face
contacting part of the mask and the mask.
BACKGROUND OF THE INVENTION
[0002] In general, conventional respirator masks consist of a face
contacting part which defines an orifice and which fits over the
patient's nose and/or mouth and provides a gas tight seal against
the patient's skin. The reverse side of the orifice is enclosed by
a manifold part for the delivery of pressurized gases to the
patient's nose and/or mouth via a gas delivery tube connected to
the manifold. Typically, the manifold part is made from a rigid
material to which an adjustable harness, for retaining the mask on
a patient's head, is attached. The geometry of the manifold is
fixed. When adjusted and placed over the patient's head, the
harness applies forces through the rigid manifold and onto the face
contacting part of the mask. The face contacting part is compressed
against the patient's face causing a gas tight seal to form between
the face contacting part and the patient's face.
[0003] Typically, the face contacting part of a conventional
respirator mask is made from a soft flexible material such as
silicone rubber. While this part will distort in one axis (the Z
axis) perpendicular to the plane of the patient's face (that plane
being the X-Y or facial plane), this part will typically not
distort substantially in the X-Y plane, in use (note that FIG. 1 of
the accompanying drawings shows the X, Y and Z axes).
[0004] This is due to the typical design features of such masks in
which a significant part of the face contacting part is relatively
thick, being several millimetres in thickness, making it
substantially inflexible under the forces which are normally
applied in use through the harness. Further, the face contacting
part is generally held in place in a single X-Y plane by the rigid
manifold which prevents any distortion of that part in the X-Y
plane. Also, the configuration of the harness and mask results in
any forces transmitted to the mask being transmitted in the Z
direction onto the face contacting part thereby tending not to
distort the mask in the X-Y plane.
[0005] In one common design of conventional mask, as well as the
relatively thicker face contacting part, the mask includes a much
thinner face sealing membrane portion attached to the face
contacting part. In use, as the face contacting portion is lowered
onto a patient's face some areas of the flexible membrane portion
will contact some parts of the patient's face before others. These
areas are compressed towards the relatively thicker, less flexible,
section of the face contacting part. Once in place, at some
sections of the interface between the mask and the patient's face,
the flexible membrane is compressed tightly against the relatively
thicker portion of the face contacting part, whereas at other
sections the membrane seals against the face but floats freely of
the relatively thicker portion. The flexible membrane provides a
gas tight seal between the relatively thicker portion and the
patient's face. In this way, such conventional masks attempt to
form a gas tight seal in a diverse range of patients having
different facial contours, which vary significantly in their X-Y-Z
topography, at the position of the mask interface. Generally
speaking, the topography of the face sealing portions of such masks
is fixed in the X-Y plane, with the flexible membrane accommodating
different facial contours in the Z direction.
[0006] Such conventional masks have a number of significant
shortcomings. In some cases, patients find them uncomfortable. In
particular, the relatively thicker sections of the face contacting
part can cause discomfort when pressed against a patient's face at
the pressures required to create a gas tight seal. This is a
particular problem where high therapeutic gas pressures are
required. In other cases, such masks do not fit properly, for
example where the mask is too narrow in the X-Y plane for the
patient's nose. Often, the bulky rigid manifold and relatively high
attachment points of the harness cause a patient's line of vision
to be impaired and this can cause a degree of claustrophobia in
some patients.
[0007] An additional problem arises from the use of rigid materials
in mask construction, particularly for the manifold. When a patient
wearing a mask having a rigid manifold turns in bed and contacts an
object such as a pillow, reaction forces from the pillow tend to
push the manifold laterally and lift the face contacting part from
the patient's face thereby breaking the gas tight seal and causing
an air leak which prevents optimum therapy being delivered to the
patient. Hard plastic components may also cause pain or discomfort
if they are pushed hard against a patient's skin during sleep.
[0008] The use of hard components also makes it difficult for a
patient to sleep on their stomach, because pressure on the manifold
tends to result in air leakage or patient discomfort. The use of
rigid manifolds also requires that a patient removes their mask, if
they wish to scratch their nose.
[0009] The design of many existing masks involves the use of
multiple plastic and silicone parts. Such masks can be difficult
for some patients to dismantle and clean. In addition parts can
become broken or lost. A mask made from many parts is typically
more expensive to produce than a mask having fewer parts, due to
increased moulding costs for the many different parts, and assembly
and inventory costs.
[0010] A further problem with existing conventional masks is that a
substantial number of patients leak gas from their mouth during
positive gas pressure therapy. In particular patients using nasal
masks may release gas from their mouths. Typically, pressurised gas
will enter a patient's oral cavity and cause the patient's cheeks
to stretch and balloon out until their mouth starts to open and the
gas pressure is released. Such patients are often treated with
full-face masks which deliver positive gas pressure both nasally
and orally. In general, these masks are similar in design to
conventional masks which only deliver gas nasally. They consist of
a rigid manifold part attached to a face contacting part, typically
made from a flexible material such as silicone. Full-face masks
have a face contacting part designed to encompass both a patient's
nose and mouth, providing a gas tight seal at the mask/face
interface in order to enable successful delivery of pressurised
gas. However one of the problems with these masks for some patients
is that they do not succeed in fully preventing gas leakage from
the patient's mouth. Often gas leakage is preceded by stretching
and ballooning of the patient's cheeks, which tends to
substantially change the facial contours adjacent the face sealing
portion of the masks. This significant facial deformation has the
effect of breaking the gas tight seal around the mask, since the
face contacting portion of the mask presents a relatively rigid
sealing surface incapable of adapting to such large changes in
facial contours.
[0011] The present invention seeks to address and attempt to
alleviate at least some of the deficiencies of the existing masks
described above.
[0012] Any discussion of documents, acts, materials, devices,
articles or the like which has been included in the present
specification is solely for the purpose of providing a context for
the present invention. It is not to be taken as an admission that
any or all of these matters form part of the prior art base or were
common general knowledge in the field relevant to the present
invention as it existed before the priority date of each claim of
this application.
SUMMARY OF THE INVENTION
[0013] In a broad aspect, the present invention provides a mask
which has a flexible manifold and face-contacting components which
can be distorted into different shapes to suit differing facial
contours when applying tensile forces to the mask, typically by
means of a straps and a harness. The nature of the connection
between the straps and the mask is such that loadings applied to
the mask via the straps are distributed so that distortions of the
mask under load will not compromise the required air seal between
the users face and the face contacting part of the mask.
[0014] More specifically the present invention provides a mask for
supplying gas under pressure to an airway of a human including:
[0015] a flexible manifold shell, being made of a flexible
material, the manifold including means for connection to a gas
delivery pipe, [0016] at least two side walls which are at least
partially comprised of portions of the manifold shell; [0017] a
first mask shape forming element for distributing distortional
forces to a substantial portion of one side wall that attaches to
or is integral with a significant portion of that one side wall of
the mask; and a second mask shape forming element for distributing
distortional forces to a substantial portion of an other side wall
that attaches to or is integral with a significant portion of that
other side wall of the mask, each mask shape forming element being
connected to, or being connectable to, a strap; [0018] a flexible
face contacting element defining a recess to accommodate the nose
of the human; [0019] wherein, forces exerted by the first and
second mask shape forming elements are, capable of deforming the
flexible face forming element and manifold in the X-Y plane to
create a variety of different mask/orifice shapes and
attitudes.
[0020] The mask further comprises: at least a third strap or mask
anchoring means disposed between the first and second mask shape
forming elements.
[0021] The X, Y and Z axes are as defined above in the background
of the invention. A significant portion of the side wall is
typically at least 50% and most preferably at least 80%, of the
extent of the side wall.
[0022] The centre of the mask shape forming elements are preferably
generally centrally located on each side wall.
[0023] The manifold shell should be of sufficient thickness to
resist major distortion by elevated pressure present in the mask in
use, while being sufficiently flexible to allow the whole mask
shape to distort into the variety of different mask/orifice shapes
and attitudes particularly when under external load and without
compromise to the required seal between the face contacting part
and a users face.
[0024] It is preferred that the first and second mask shape forming
elements are integral with side straps and comprise webs at the
ends of the side straps which join the side walls of the mask. The
ends of the straps distal from the manifold preferably define a
slot or other means for connection of the strap to a harness.
[0025] In use, tension on these side straps when pulled laterally
in the horizontal plane (X-axis) is transmitted through the mask
shape forming elements to the manifold shell and face contacting
portion and can cause the general shape of the mask to be in one
extreme elongated in the general direction of the lateral tension
or alternatively tension applied on these side straps downward in
the horizontal direction (Y-axis) with an opposing force applied to
the third strap or mask anchoring means causes the shape of the
mask to be elongated in the general direction of this horizontal
tension.
[0026] The third strap is most typically a nasal arch strap which
optionally defines at least part of an air inlet pipe.
[0027] Preferably, the tensile load transmitted axially through the
side straps and via gussets/webs which distribute the axial load
along the manifold body.
[0028] Preferably the web is tapered inwards in the Y direction and
as it locates towards the top region of the manifold
[0029] In an alternative related aspect, the invention may be
considered to be a mask incorporating three elements. [0030] a
first element of the mask is a flexible manifold shell. This
element is disposed on a non-face contacting portion of the mask,
encloses the mask and has a connection for a gas delivery pipe that
may also be flexible. It is made of a flexible material and is of
sufficient thickness to resist major distortion by elevated
pressure within the mask. The gas delivery pipe may be connected at
the top of the manifold or alternatively it may engage that part of
the manifold at the front of the mask.
[0031] However it is sufficiently flexible to allow the whole mask
shape including the flexible manifold shell and the face contacting
element to be distorted into a wide range of general shapes.
[0032] A second element of the mask is a mask shape forming element
that is used to distribute distortional forces to a substantial
portion of the perimeter of the side wall of the mask, the side
wall being made up of at least a portion of the manifold shell.
[0033] This shape forming perimeter element is connected to a
series of straps extending away from the side wall of the mask,
generally with at least one strap on each side of the mask and one
strap running along the nasal arch of the forehead.
[0034] The shape forming element attaches to or is integral to the
side wall of the 25 mask. The straps have a mechanism to connect to
a harness at one end.
[0035] Tension on these side straps, when pulled in the direction
of the X-axis is transmitted through the mask shape forming element
to the first and third elements and can cause the general shape of
the mask to be in one extreme elongated in the general direction of
this tension or alternatively tension applied on these side straps
downward in the Y direction Y with an opposing force applied to the
nasal arch strap causes the shape of the mask to be elongated in
the general direction of this horizontal tension.
[0036] A third element of the mask is a flexible face contacting
element with an orifice to accommodate the nose or mouth and nose
of the subject. The orifice approximates the shape of the perimeter
of the base of the nose or mouth and nose. The orifice is formed
where this third element's surface, furthest from the manifold
shell element, curves inwardly towards the centre of the mask in
the general X-Y plane to form the gas sealing surface but leaves
the nares in unobstructed communication with the inside of the
mask.
[0037] The face contacting element joins the flexible manifold
shell element and/or the shape forming element such that when the
side straps are pulled back across the checks in a direction that
passes below the ears and the nasal arch flexible strap is pulled
toward the top of the head (Z-axis), the mask is pulled onto the
face such that the face contacting element orifice encapsulates the
subjects nose or nose and mouth and causes the face contacting
element to provide an airtight seal between the mask and patient's
skin.
[0038] This element is flexible enough to allow it to be pulled
into a wide range of general mask shapes so as to vary its shape in
the X-Y plane. Flexibility is also required in manufacture to
enable the mask to be stripped from its mould cavity.
[0039] Variation in the direction and magnitude of the forces
exerted from the straps through the shape forming element can be
used to vary the magnitude of the gas sealing forces exerted
between the subjects skin and the flexible face contacting element
at different points round this element.
[0040] Most preferably, the third strap is a nasal arch strap and a
portion of a mask shape forming element is integral to a portion of
the gas delivery pipe. Preferably, the manifold is sufficiently
flexible to collapse towards the patients nose when a moderate
external force is applied to it.
[0041] Preferably the manifold shell, mask shape forming elements,
side walls and face contacting elements are integrally moulded in
one piece from an elastomeric material such as silicone rubber,
with, optionally, at least a part of the side straps and/or the
nasal arch strap and/or air inlet pipe
[0042] The mask is also preferably sufficiently flexible to enable
a patient to remove it or fix it in position without having to
adjust any harness connection points where a harness connects to
the straps of the mask.
[0043] The face contacting portion of the mask typically defines an
inwardly curving 30 gas sealing surface which in use contacts the
patient's face. Typically the mask further includes a series of gas
bleed holes defined in the manifold shell.
[0044] Advantageously, a mask embodying the present invention may
be compressed into an approximate ball shape using a moderate level
of hand/digital pressure, and may weigh less than 50 grams
including the weight of the straps.
[0045] It is preferred that the relative thicknesses of different
sections of the flexible manifold and/or flexible face contacting
portion are varied so as to vary the amount of stretch in different
areas of the mask when forces are applied to the mask from the
straps through the mask shape forming element in various
directions.
[0046] Typically the manifold includes ribbing. It is preferred
that the interior surfaces of the mask are generally smooth, which
makes cleaning of the mask relatively easy.
[0047] It is preferred that the manifold is flexible enough to
collapse toward the patients nose when a moderate external force is
applied to it, to allow, for example, a patient to scratch their
nose without removing the mask. With the mask in situ, the manifold
can be distorted onto the patient's nose without breaking the
airtight seal between the face contacting element and the patients
skin. This also means that when a patient turns in sleep and their
mask contacts a pillow or some other object the manifold will
deform and/or displace rather than be pushed against the patient's
face. The mask face contacting element is preferably flexible and
allows a rolling reaction in the mask as loadings are applied via
the straps. The mask shape forming element may include a planar
band which attaches to or is integral to a significant portion of
the side wall of the mask. The planar band may be used for
assisting in the correct location of the mask by locating on the
patient's top lip, in use.
[0048] In a preferred embodiment, the mask shape forming element
may provide multiple attachment points to the straps and/or
flexible mask which can be adjusted in length so as to change the
distribution of forces to various areas of the flexible mask,
through tension exerted in any specific direction on to the
straps.
[0049] In a yet further embodiment, the mask shape forming element
may have attachment points to the straps and/or flexible mask which
can be adjusted in their attachment position so as to change the
distribution of forces to various areas of the flexible mask,
through tension exerted in any specific direction on to the
straps.
[0050] In a yet further embodiment, the mask shape forming element
may be varied in its relative stiffness at different points around
its attachment position to the flexible perimeter of the mask side
wall so as to change the distribution of forces to various areas of
the flexible mask, due to tension exerted in any specific direction
on to the straps.
[0051] The adjustable mask shape forming elements may be varied in
order to change the flexible mask shape and/or the gas sealing
pressure between different parts of the face contacting element and
the patients skin.
[0052] The mask is preferably sufficiently flexible to enable a
patient to remove it or fix it in position without having to adjust
the harness connection points where they connect to the straps.
[0053] The mask will typically be used in combination with a device
for supplying gas, typically air, at a positive pressure to the
patient's mouth, either through the patient's nose or through their
nose and mouth.
[0054] It is preferred that a means is provided for preventing
leakage from the patient's mouth while positive pressure is
delivered to the patient's nose.
[0055] In use, the shape of the mask during its ongoing operation
on the patients face in the general X-Y dimension can be varied by
first applying tension to the straps in the general X-Y planar
direction, prior to fixing the face contacting element onto the
patients face, in order to form the required mask shape. Then while
maintaining the desired shape, an additional downward tension may
be applied on the straps in the vertical Z-direction in order to
fix the face contacting element on to the patients face. Then the
harness tension may be adjusted in order to maintain this desired
mask shape in its X-Y-Z dimensions.
[0056] It is preferred that, the mask's shape on the patient's face
may be changed in situ by applying external pressure to it's
flexible manifold and/or face contacting portion in order to stop
gas leakage from the mask, in use.
[0057] In one embodiment, the flexible face contacting portion
includes side walls, extending in the general Z-axis direction, one
end of the side walls being attached to the first and second
elements, the other end being attached to the inwardly curving gas
sealing surface of the face contacting element.
[0058] In one embodiment, the flexible face contacting portion
includes side walls, extending in the general Z-axis direction, one
end of the side walls being attached to an inwardly directed
generally concertina shaped wall. Either the side walls in the
general Z-axis direction or the concertina walls may be connected
to the manifold and shape forming elements. The other end of the
flexible face contacting element furthest from the mask shape
forming elements is attached to the inwardly curving gas sealing
surface of the face contacting element.
[0059] In an alternative embodiment to that described above, the
concertina shaped wall is outwardly directed.
[0060] The flexible face contacting element is preferably
sufficiently flexible that it substantially collapses onto the
patient's face under the normal forces exerted on it by the harness
and straps when in situ, in use. The mask will preferably inflate
under normal operating pressures when in situ on a patient's face,
but will preferably not significantly distend in comparison with
the mask's "resting" shape.
[0061] It is preferred that the manifold shell has an average wall
thickness of less than 2 5 mm, preferably I mm to 2 mm, most
preferably about 1.5 mm. In a preferred embodiment, the flexible
face contacting portion has as average wall thickness of less than
1.5 mm, preferably 0.3 mm to 0.7 mm, most preferably about 0.5
mm.
[0062] The side straps may be generally curved to follow the
general shape of the contours of a patient's cheeks, in situ.
[0063] The face contacting portion may collapse substantially onto
the patient's face when located in position on the patient's face
with the harness and straps correctly adjusted. The mask will
typically collapse inwardly towards the patient's face during
normal inspiratory effort when the mask is in position and attached
to a positive gas pressure device which is not delivering a
positive pressure gas flow.
[0064] The manifold will typically inflate to maintain its shape
when subject internally to positive gas pressure.
[0065] The straps may cover a substantial portion of the patient's
cheeks and prevent inflation of the patient's cheeks during
delivery of positive airway pressure therapy.
[0066] The flexible face contacting portion/element may provide a
substantially gas tight seal between the mask and the patient's
face when the mask is subject to internal gas pressure.
[0067] The mask shape forming element may comprise at least three
continuous sections, each attached to a strap, where the sections
in total connect to at least 40% of the length of the side wall of
the mask.
[0068] The mask shape forming element may have multiple connections
to the side wall of the mask, with more than one connection
attached to some straps, where a portion of the perimeter
delineated by the connection points and positions extending 2 cm on
either side of these points makes up at least 40% of the total
perimeter of the side wall of the mask. Whether the shape forming
elements are distributed along the walls of the mask continuously
or as a series of point loads there will be an overall length
measurement the limits of which define an overall contact length.
Thus the loading may be transmitted as a distributed load or as a
series of distributed point loads.
[0069] When subject to internal positive gas pressure, if leaking
occurs between the patient's facial skin and the face contacting
portion, the leakage may be stopped by manually distorting the
flexible part of the mask while is position and thereby changing
the force profile around the mask/sealing surface and/or changing
the X-Y sealing plane.
STATEMENTS OF INVENTION
[0070] In its broadest form the present invention comprises: [0071]
a mask for supplying gas under pressure to an airway of a human
including: [0072] a flexible manifold shell, being made of a
flexible material, the manifold including means for connection to a
gas delivery pipe, [0073] at least two side walls which are at
least partially formed by portions of the manifold shell; [0074] a
flexible face contacting element defining an orifice to accommodate
the nose of the human; [0075] a first connecting strap having a
first end connected to the mask and a second end connectable to a
mask retaining strap; [0076] a second connecting strap having a
first end connected to the mask and a second end connectable to the
mask retaining strap; [0077] wherein, the first strap and the
second strap engage respective side walls of the mask for
distributing opposing distortional forces to a substantial portion
of the respective side walls when the mask is in use; [0078]
wherein the connection of the straps to the mask allow forces
exerted by the first and second straps are capable of deforming the
manifold at least along X and Y axes to create a variety of
different mask/orifice shapes; [0079] wherein, the manifold of the
mask has a manifold height and a centroid; and [0080] wherein the
first and second straps engage the mask along a connecting length
thereby joining the first and second straps to respective side
walls of the mask so that an axis through the centroid normal to
the Y axis, intersects with at least part of each strap.
[0081] In another broad form the present invention comprises:
[0082] a mask for supplying gas under pressure to an airway of a
human including: [0083] a flexible manifold shell, being made of a
flexible material, the manifold including means for connection to a
gas delivery pipe, [0084] at least two side walls which are at
least partially comprised of portions of the manifold shell; [0085]
a first mask shape forming element for distributing distortional
forces to a substantial portion of one side wall that attaches to
or is integral with a significant portion of that one side wall of
the mask; and [0086] a second mask shape forming element for
distributing distortional forces to a substantial portion of an
other side wall that attaches to or is integral with a significant
portion of that other side wall of the mask, each mask shape
forming element being connected to, or being connectable to, a
strap; [0087] at least a third strap or mask anchoring means
disposed between the first and second mask shape forming elements;
[0088] a flexible face contacting element defining an orifice to
accommodate the nose of the human; [0089] wherein forces exerted by
the first and second mask shape forming elements are, in
conjunction with the third strap or mask anchoring means, capable
of deforming the flexible face forming element and manifold in the
X and Y planes to create a variety of different mask/orifice
shapes; [0090] characterised in that the manifold of the mask is
defined by; [0091] a manifold height extending along a Y axis; and
[0092] the shape forming elements define a connecting length
joining the respective first and second shape forming elements to
each wall; wherein a ratio of height of the manifold to connecting
length falls within the range 0.8-2.0.
[0093] Preferably the mask allows distribution of pressure on the
margins along a Z axis to retain a seal at the margins of the mask.
The straps may be used to adjust the mask in a case for instance
where there is a leak at the bridge.
[0094] In another broad form the present invention comprises:
[0095] a mask for supplying gas under pressure to an airway of a
human including: [0096] a flexible manifold shell, being made of a
flexible material, the manifold including means for connection to a
gas delivery pipe, [0097] at least two side walls which are at
least partially comprised of portions of the manifold shell; [0098]
a first mask shape forming element for distributing distortional
forces to a substantial portion of one side wall that attaches to
or is integral with a significant portion of that one side wall of
the mask; and [0099] a second mask shape forming element for
distributing distortional forces to a substantial portion of an
other side wall that attaches to or is integral with a significant
portion of that other side wall of the mask, each mask shape
forming element being connected to, or being connectable to, a
strap; [0100] a flexible face contacting element defining an
orifice to accommodate the nose of the human; [0101] wherein forces
exerted by the first and second mask shape forming elements are,
capable of deforming the flexible face forming element and manifold
in the X and Y planes to create a variety of different mask/orifice
shapes; [0102] characterised in that the manifold of the mask is
defined by; [0103] a manifold height extending along a Y axis; and
[0104] the shape forming elements define a connecting length
joining the respective first and second shape forming elements to
each wall; wherein a ratio of height of the manifold to connecting
length falls within the range 0.8-2.0.
[0105] According to one embodiment the contact length of the web is
determined by the sum of separate contact lengths formed by at
least one abbreviation in the web. In each configuration of the
web, within the scope of the present invention, a resultant force
will act through a centroid of the load distribution
[0106] In another broad form the present invention comprises:
[0107] a mask for supplying gas under pressure to an airway of a
human including: [0108] a flexible manifold shell, being made of a
flexible material, the manifold including means for connection to a
gas delivery pipe, [0109] at least two side walls which are at
least partially comprised of portions of the manifold shell; [0110]
a first mask shape forming element for distributing distortional
forces to a substantial portion of one side wall that attaches to
or is integral with a significant portion of that one side wall of
the mask; and [0111] a second mask shape forming element for
distributing distortional forces to a substantial portion of
another side wall that attaches to or is integral with a
significant portion of that other side wall of the mask, each mask
shape forming element comprising a generally triangular shaped web
one side of which engages the manifold wall and being connected to,
or being connectable to, a strap; [0112] a flexible face contacting
element defining an orifice to accommodate the nose of the human;
[0113] wherein forces exerted by the first and second mask shape
forming elements are, capable of deforming the flexible face
forming element and manifold in the X and Y planes to create a
variety of different mask/orifice shapes; [0114] characterised in
that the manifold of the mask is defined by; [0115] a manifold
height extending along a Y axis; and the shape forming elements
define a connecting length joining the respective first and second
shape forming elements to each wall; wherein a ratio of height of
the manifold to connecting length falls within the range 0.8-2.0;
wherein a resultant force applied from distribution of load
thorough said web over a predetermined length of web or over a span
of point loads applied to the web lies approximately in a middle
third of the manifold height to allow the mask to accommodate
distortion from such applied load.
[0116] Height of the manifold may be taken to refer to that
distance from a lowermost wall of the masks which normally engages
a face of a wearer to an uppermost wall or apex of the mask which
engages a nose bridge of a user.
[0117] Connecting length is defined as a distance along a mask
wall, (i.e. that part of the wall which extends from the upper lip
to the bridge of the nose) between extremities of contact of the
shape forming elements and the wall location at which they contact
the manifold.
[0118] A preferred ratio of manifold height to wall length is in
the region of 1.2. A preferred ratio of the web connection length
to wall length of the manifold is 0.3 but may fall within the range
of 0.3-1.0
[0119] The X, Y and Z axes are as defined above in the background
of the invention. A significant portion of the side wall is
typically at least 50% and most preferably at least 80%, of the
extent of the side wall.
[0120] In an other broad form the invention comprises: a mask made
from a flexible material and having at least one side section
including a face contacting part; [0121] wherein, one of the side
sections of the face contacting part are provided with a thickening
in the walls over at least part of the side section.
[0122] Preferably, both side sections of the face contacting part
are provided with a thickening in the walls over at least part of
the side sections. The wall thickenings may be abrupt or gradual
according to design requirements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0123] Aspecific embodiment of the present invention will now be
described, by way of example only, and with reference to the
accompanying drawings, in which:
[0124] FIG. 1 illustrates the X,Y and Z facial axes of a
patient;
[0125] FIG. 2 is a front view of an embodiment of a mask in a
neutral un-tensioned state;
[0126] FIG. 3 is a front view of the mask of FIG. 2 showing tension
applied to a shape forming element of the mask to stretch the mask
in the Y axis;
[0127] FIG. 4 is a front view of the mask of FIG. 2 showing tension
applied to a shape forming element of the mask to stretch the mask
in the X axis;
[0128] FIG. 5 is a rear view of the mask of FIG. 2 in a neutral
un-tensioned state;
[0129] FIG. 6 is a rear view of the mask of FIG. 5 showing tension
applied to a shape forming element of the mask to stretch the mask
in the Y axis;
[0130] FIG. 7 is a rear view of the mask of FIG. 5 showing tension
applied to a shape forming element of the mask to stretch the mask
in the X axis;
[0131] FIG. 8 is a side view of the mask of FIG. 2 in a neutral
un-tensioned state;
[0132] FIG. 9 is a side view of the mask of FIG. 5 showing tension
applied to a shape forming element of the mask to stretch the mask
in the Y axis;
[0133] FIG. 10 is a side view of the mask of FIG. 5 showing tension
applied to a shape forming element of the mask to stretch the mask
in the X axis;
[0134] FIG. 11 is a front view of a yet further embodiment of a
mask in a neutral un_tensioned or un distorted state;
[0135] FIG. 12 is a front view of a yet further embodiment of a
mask in a neutral un tensioned or undistorted state;
[0136] FIG. 13a is a front view of a yet further embodiment of a
mask in a neutral un tensioned or undistorted state;
[0137] FIG. 13b is a side view of the embodiment of FIG. 13a;
[0138] FIG. 14a is a rear view of the mask of FIG. 13a;
[0139] FIG. 14b is a top plan view of the mask of FIG. 13a;
[0140] FIG. 15a is a rear view of a yet further embodiment of a
mask in a neutral un_tensioned or undistorted state;
[0141] FIG. 15b is a top plan view of the embodiment of FIG.
15a;
[0142] FIG. 16a is a front view of the mask of FIG. 15a;
[0143] FIG. 16b is a side view of the mask of FIG. 15a;
[0144] FIG. 17a is a side view of a yet further embodiment of a
mask in a neutral un_tensioned state;
[0145] FIG. 17b is a rear view of the embodiment of FIG. 17a;
[0146] FIG. 18 is a side view of a full-face mask embodying the
present invention;
[0147] FIG. 19 is a front view of the mask of FIG. 18;
[0148] FIG. 20 shows a variant of the mask of FIGS. 18 and 19.
[0149] FIG. 21 is a side view of the mask of FIG. 20; and
[0150] FIG. 22 shows a further embodiment of a full-face mask.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0151] Referring to the drawings, FIG. 1 shows a schematic view of
a face indicating the X, Y and Z axes. FIGS. 2 to 10 schematically
illustrate a first embodiment of a mask 1 and the principles
governing the design and operation of that mask in response to the
use of an enlarged web contact portion. FIG. 2 shows a back side
elevation of the mask 1. Mask 1 includes a flexible face contacting
element 2 and straps 3 and 4. Each of straps 3 and 4 respectively
include enlarged web portions 5 and 6 which transfer loads from the
straps to the manifold. Mask 1 has been moulded in a single piece
from a flexible elastomeric material, most preferably a medical
grade silicone. However, any suitable elastomeric material may be
used. Mask 1 further includes a third strap 7 and an air inlet 8 .
The mask of FIG. 1 is shown in a configuration without applied
loads. FIG. 3 shows the mask 1 of FIG. 1 with corresponding
numbering. The mask in FIG. 3 is shown with straps under a load
creating a distortion in the face contacting element 2. FIG. 4
shows the mask 1 of FIG. 2 with opposing loading applied to straps
3 and 4. In this embodiment a resultant force is applied to a
manifold (obscured) causing distortion of the face contacting part
2 but without compromising a seal when the mask is attached to a
face of a wearer.
[0152] FIG. 5 shows the mask 1 of FIG. 2 from the opposite side and
with corresponding numbering. The mask in FIG. 5 is shown with
straps unloaded and with the manifold 9 in a neutral position.
under a load creating a distortion in the face contacting element
2. Mask 1 includes a flexible central manifold 9 and a flexible
integral face contacting element 2. An annular air inlet pipe 14
extends away from the manifold 9 to a generally cylindrical outlet
15 at a distal end of the air inlet pipe 14. A nasal bridge strap
16 extends away from the top of the manifold 1. Two straps 3 and 4
extend away from opposite sides of the manifold 9 in a direction
which is generally perpendicular to the longitudinal axis of the
nasal bridge strap 16. The distal ends of straps 3 and 4 includes
connecting tabs 17 and 18 for attaching the mask to a harness. As
shown in FIG. 5, the proximal ends of the straps at webs 19 and 19a
where the straps meet the sides of the manifold 9 are relatively
wide and in this non limiting embodiment the extent of the strap at
its proximal end extends almost the entire length of the side of
the manifold 9.
[0153] The wall thickness of the manifold and face contacting
portion 2 is thin enough to enable patients to stretch and compress
different parts of the mask through the application of forces from
the harness with a magnitude normally used with current
conventional respirator masks. However, the wall thickness while
relatively thin is also large enough to withstand therapeutic gas
pressures. The distortional forces applied to the mask from the
harness are distributed around the body of the flexible mask using
a mask shape forming component, which is integral to (or may be
attached to) the sidewall of the mask. The shape-forming components
(webs) are designed to distribute distortional forces to a
substantial portion of the mask sidewall. These forces are then
transmitted from the mask sidewall to the remainder of the mask
body. This outcome may be achieved using a range of shape forming
component designs, although in the embodiment of FIGS. 2 to 10, the
mask shape forming elements comprise the proximal ends (webs 19 and
19a) of the straps 3 and 4 in particular, where they meet the side
wall of the mask/manifold.
[0154] FIG. 6 shows from an opposite side the mask 1 of FIG. 3 with
opposing loading applied to straps 3 and 4. In this embodiment a
resultant force is applied to a manifold 9 causing distortion of
the face contacting part 2 but without compromising a seal when the
mask is attached to a face of a wearer.
[0155] FIG. 7 shows from an opposite side the mask 1 of FIG. 4 with
opposing loading applied to straps 3 and 4. In this embodiment
opposing forces are applied to the straps 3 and 4 causing a
distortion in the manifold 9.
[0156] FIG. 8 is a side view of the mask of FIG. 2 in a neutral
un-tensioned state and with corresponding numbering. Loading on the
shape forming element (strap 4) is in the direction of arrow 10.
FIG. 8 is a schematic side view of the mask in a "neutral" position
illustrating that when generally equal tensile forces are applied
to the mask, via straps 3, 4 and 7 with the forces applied to the
side straps being generally perpendicular to the nasal bridge strap
7. FIG. 9 is a side view of the mask of FIG. 8 showing tension
applied in the direction of arrow 11 to a shape forming element
(strap 4) of the mask 1 to stretch the mask along the X and Y axes.
FIG. 9 illustrates that where the straps 3 and 4 are pulled
downwardly at an obtuse angle to the nasal bridge strap 18,
increased sealing pressure occurs at the top portion 30 of the
facecontacting element, adjacent to the bridge of the patient's
nose.
[0157] FIG. 10 is a side view of the mask of FIG. 8 showing tension
applied to the shape forming element (strap) 4 of the mask 1 in the
direction of arrow 12 to stretch the mask along the X axis. This
increases sealing pressure at the upper lip region 13 of the face
contacting part 2.
[0158] FIG. 11 shows a front view of a mask 20 according to an
alternative embodiment in a neutral un_tensioned or un distorted
state. Mask 20 includes a flexible face contacting element 21 and
straps 22 and 23. Each of straps 22 and 23 respectively include
enlarged web portions 24 and 25 which transfer loads from the
straps to the manifold 26. Mask 20 is moulded in a single piece
from a flexible elastomeric material, most preferably a medical
grade silicone. Mask 20 further includes a third strap 27 and an
air inlet 28. Mask 20 is shown in a configuration without applied
tension loads to straps 22 and 23 inducing distortion. Webs 24 and
25 are characterised in having a series of point load connections
at the walls of manifold 26. Web 24 terminates in point connections
29 and web 25 terminates in point connections 30.
[0159] FIG. 12 is a front view of a yet further embodiment of a
mask in a neutral un_tensioned or undistorted state. shows a front
view of a mask 40 according to an alternative embodiment in a
neutral un_tensioned or un distorted state. Mask 40 includes a
flexible face contacting element 41 and straps 42 and 43. Each of
straps 42 and 43 respectively include enlarged web portions 44 and
45 which transfer loads from the straps to the manifold 46. Mask 40
is moulded in a single piece from a flexible elastomeric material,
most preferably a medical grade silicone. Mask 40 further includes
a third strap 47 and an air inlet 48. Mask 40 is shown in a
configuration without applied tension loads to straps 42 and 43
inducing distortion. Webs 44 and 45 are characterised in having a
series of point load connections at the walls of manifold 46. Web
44 terminates in point connections 49 and web 45 terminates in
point connections 50.
[0160] A more detailed description of the construction of other
embodiments follows the description of FIG. 14a and later Figures.
The mask 10 is designed for pressurised gas delivery to a patient's
nose only.
[0161] FIGS. 2 to 7 show how the mask may be distorted in the X-Y
plane by application of forces to the straps. FIGS. 2 and 5 show
the mask in a "neutral"position where no tension is applied to the
shape forming element via the straps 3 and 4. FIGS. 3 and 6 show
how the mask distorts when tensile forces F1, F2, F3 are applied to
all three straps. In this example the mask becomes elongated in the
Y-axis and compressed in the X-axis, suiting a patient with a long
thin nose. FIGS. 3 and 6 show tensile forces F4 and F5 applied to
the shape forming element via the side straps 3 and 4. In this
example the mask becomes elongated in the X axis and compressed in
the Y-axis, suiting a patient with a relatively wide nose.
[0162] FIGS. 8 to 10 show how the application of forces in
different directions through the straps affects the forces exerted
by the face contacting portion 2 on the patient. This contrasts
with existing masks where the face contacting portion is relatively
fixed in the X-Y plane. FIG. 10 illustrates that where the straps 3
and 4 are pulled more upwardly at an acute angle to the nasal
bridge strap 7, increased sealing pressure occurs at the bottom
portion 2a of the face contacting element 2, adjacent to the
patient's nares.
[0163] Hence, in addition to being able to change the shape of the
mask, its flexible 30 nature allows patients to adjust the sealing
forces between the face contacting portion and the patients skin at
various points around the perimeter of the mask. In particular, it
is possible to adjust the relative size of those forces at
different points around the face contacting portion. This is also
achieved by varying the forces applied to specific areas of the
face contacting portion by adjusting the level and direction of
forces applied to the mask from the harness.
[0164] FIGS. 11 and 12 show variants of the mask in which different
shape forming elements are provided. In the mask of FIG. 12 the end
of the strap 20 proximal to the side wall of the mask where the
strap connects to the side wall is spilt into four spaced apart
fingers 34 which attach to the side wall at four respective points
spaced along the length of the side wall. The other strap 22 is
attached in the same way. In FIG. 13 the shape forming element of
the mask 10b is adjustable. In particular there is an integrally
formed flange 36 which extends along the length of each side wall
of the mask 10b. A series of spaced apart holes 38 are defined
along the length of each flange 36. In this case the straps 40 for
attachment to a harness define a plurality of fingers 42 which are
pivoted to the straps 40. The end of each finger distal from the
pivot defines a protrusion which push or snap fits into a hole in
the flange. The attachment points of the fingers on the flange may
be changed to adjust the effect of tension applied to the straps 40
and the distribution of tensile forces to the mask body.
[0165] Variation of the relative thickness of wall sections
throughout the mask will also is change the amount of stretch or
compression achieved at these positions through the administration
of any given magnitude and direction of forces through the shape
forming element. Variation of mask wall thickness would typically
be achieved by variation of the moulds used for mask production.
The forces of the mask may be altered by changing the size and/or
direction of forces on the straps.
[0166] There are a number of preferred embodiments of the mask for
covering the nose only, each of which is made from a single
component including the mask manifold, face contacting component,
mask shape forming component, gas tubing connector and straps (see
FIGS. 14 to 18).
[0167] FIGS. 13a shows a rear elevation of a mask 60 according to
an alternative embodiment. FIG. 13b shows the mask of FIG. 13a
rotated 90 degrees. Mask 60 includes a flexible face contacting
element 61 and straps 62 and 63. Each of straps 62 and 63
respectively include enlarged web portions 64 and 65 which transfer
loads from the straps 62 and 63 respectively to the manifold 66.
Mask 60 has been moulded in a single piece from a flexible
elastomeric material, most preferably a medical grade silicone.
However, any suitable elastomeric material may be used. Mask 60
further includes a third strap 67 and an air inlet 68. The mask of
FIG. 13a is shown in a configuration without applied loads and
further comprises a gas inlet pipe 68 and nasal bridge strap 69
which are integrally constructed. FIG. 14a is a rear view of the
mask 60 of FIG. 13a and FIG. 14b is a top plan view of the mask 60
of FIG. 13a. with corresponding numbering.
[0168] FIGS. 15a shows a front elevation of mask 70 and FIG. 15b
shows a plan view of the mask of FIG. 15a. Mask 70 comprises a
manifold 71 including a gas inlet pipe 72 and the nasal bridge
strap 73. FIG. 16a is a front view of the mask 70 of FIG. 15a. FIG.
16b is a side view of the mask 70 of FIG. 15a;
[0169] FIG. 17a is a side view of a yet further embodiment of a
mask 80 in a neutral un_tensioned state. FIG. 17b is a rear view of
the embodiment of the mask 80 of FIG. 17a. In mask 80 shown in
FIGS. 17a and 17b, the face-contacting component incorporates a
flexible concertina section or groove 81. Mask 80 includes a
flexible face contacting element 81 and straps 82 and 33. Each of
straps 82 and 83 respectively include enlarged web portions 84 and
85 which transfer loads from the straps 82 and 83 respectively to
the manifold 86. Mask 80 has been moulded in a single piece from a
flexible elastomeric material, most preferably a medical grade
silicone and further includes a third strap 87 and an air inlet 88.
The mask of FIG. 17a and 17b is shown in a configuration without
applied loads and further comprises nasal bridge strap 89 which is
integrally constructed.
[0170] In all three masks 60, 70 and 80 the face-contacting
component is flexible enough that it substantially collapses down
onto the patient's face, which facilitates the formation of an
airtight seal between this component and the patients face. This
feature enables it to conform to a range of contours along the
Z-axis of the face, which vary substantially from patient to
patient.
[0171] These versions provide a number of advantages in comparison
to many current conventional masks. They are more comfortable
because they are made totally from soft flexible silicone. In
addition they weight significantly less so that the patient is less
aware of the mask on their face (i.e. less than 50 gm versus more
than 100 gm for many current conventional masks.
[0172] The profile is generally smaller on the patient's face
resulting in less of their field of view being blocked by the mask.
This tends to reduce the feeling of claustrophobia that some
patients feel.
[0173] Each mask size can potentially fit a wider range of
patient's faces due to the ability to substantially distort its
shape in the X, Y and Z directions. There is less likelihood of
breakage because there are no hard plastic components.
[0174] The cleaning process is simplified since it is not necessary
to dismantle the mask and there are less crevices, which can hold
dirt and micro organisms. If required the whole mask can be
sterilized by autoclaving whereas this is not possible with many
existing plastic mask components. The mask can be adjusted to
change the shape of the mask and sealing forces around the face
sealing interface if leakage occurs, without taking the mask off,
or adjusting the harness connectors.
[0175] The patient can sleep with the mask in contact with objects
such as a pillow. In comparison with conventional masks, the
resultant forces applied to the mask by the object do not tend to
cause the face-sealing surface to lift off the face and result in
gas leakage. This is because the applied force tends to distort the
manifold shape rather than lift the mask off the face. The patient
can remove the mask without having to disconnect the harness
because the mask, straps and harness are flexible and soft and can
therefore stretch and be removed from the face without discomfort.
This is useful if a patient wishes to remove and replace the mask
at night in the dark.
[0176] If a patient has discomfort on the skin under the mask (such
as an itch) they can massage or scratch it by distorting the mask
manifold or other components on the affected part and massaging it
through the mask wall.
[0177] In a mask developed specifically for covering both the nose
and mouth the advantage of having a fully flexible version,
compared to conventional masks, is even more significant than in
the case of the version for covering the nose only. As discussed
above, the facial contours around the perimeter of the nose vary
significantly from patient to patient. However, the contours of the
facial tissue of any specific patient tend not to change during the
night since they are fixed by the underlying bone structure. In
contrast, the contours around the facial tissue of the perimeter of
the mouth and nose together vary significantly from patient to
patient and in addition vary for each patient as they move their
jaw relative to their nose. A mask which is flexible in 3
dimensional space will distort its shape as the patient's jaw moves
relative to their nose. The ability of the masks face contacting
part to move in real time in the X, Y and Z directions, as the
patients facial contours change, enables this new mask to prevent
mask leakage.
[0178] FIG. 19 shows a full face mask 90 in situ on a patients face
91. The manifold shape forming elements, which are webs 92
according to a preferred embodiment, are largely the same as the
mask of FIGS. 2 to 10 but are larger so that they encompass the
patient's mouth and nose. However, in this preferred version, in
addition to its attachment around the perimeter at the sides and
top of the mask, the shape forming element also attaches to a
significant portion of the bottom perimeter of the mask. At this
point an additional lower strap section 93 pulls this lower portion
towards the patients chin. In this embodiment the side straps 92
also cover a significant portion of the patients cheeks thereby
reducing the ability of the cheeks to balloon and leak due to
internally delivered gas pressure.
[0179] FIG. 20 shows according to an alternative embodiment, a rear
(patient side) elevation of a mask 100 including a face contacting
part 101 and straps 102 and 103 which comprise the webs 104 and 105
of the shape forming elements of the straps 102 and 103. Mask 100
further comprises an auxiliary fixation arrangement 106 including
auxiliary straps 107 and 108. Auxiliary fixation arrangement 106
pulls mask 100 towards the patients chin. In this embodiment the
side straps 107 and 108 also cover a significant portion of the
patients cheeks (not shown) thereby reducing the ability of the
cheeks to balloon and leak due to a break in the seal allowing
escape of internally delivered gas.
[0180] FIG. 21 shows another embodiment of a full face flexible
mask 110 which also has a flexible locating band 111 attached to
the side wall of the face contacting element. When the mask is
placed on the patients face this band 111 locates and sits on the
patient's upper lip between their nose and mouth. The band 111
helps to locate and hold the mask 110 in place as the patients jaw
opens and moves relative to their nose. Other preferred versions
may incorporate similar shape forming element, strap, face
contacting element, gas tubing delivery connector and other design
features as outlined in FIGS. 2 to 17b for the nose only version of
the flexible mask. In each case the full face design also
incorporates a portion of the shape forming element and related
straps designed to provide tension on the flexible mask in the
general direction of the chin as shown in FIGS. 20, 21 and 22.
[0181] FIG. 22 shows an alternative embodiment of a mask 120 for
covering a patient's nose and mouth in order to prevent mouth
leakage. In contrast to the conventional more rigid full face masks
the mask 120 can conform to the changing facial contours as the
mouth moves. In this mask, gas pressure is delivered to the nose
only, while the structure covering the patient's mouth acts to
prevent air leakage from the mouth. In this embodiment of the full
face flexible mask, the side straps 121 cover the patient's cheeks
thereby reducing the patient's ability to inflate or balloon their
cheeks leading to gas leakage.
[0182] In each embodiment shown, the mask effectively `floats` on
the flexible membrane such that the manifold is capable of X or Y
axis movement relative to the face engaging membrane. This allows
movement in the mask and specifically in the manifold when under
loads in either the X-Y or Z directions, allowing the membrane to
deform or displace in a rolling motion to retain a gas seal on the
face of a wearer. The larger contact length between the web and the
manifold walls have numerous advantages. For example, in a case
where the mask is pressured in a Y direction and tends to lift of
the face, the high contact length webs, help the mask to better
accommodate the lifting off tendency by significantly enhanced load
distribution through the manifold. The increase in contact length
imparts advantages under various load geometries applied to the
mask. The larger web connection to the walls of the mask causes a
resultant force to be applied closer to the mid height region of
the mask. This is so with both the full contact web and the point
load contact embodiments as a resultant or notional resultant in
the case of the point load embodiment will lie at a location
generally in the middle third of the height of the manifold so that
the load will be more evenly distributed. In other words the
resultant loading is optimally applied above a neutral axis of the
manifold. On its face this is against conventional wisdom as this
places the resultant load at a location which would cause the
straps to engage the users ear. This would normally motivate away
from an adjustment in design which places the resultant force in a
compromising location and more particularly around the middle third
of the manifold. The web feature of the present invention combines
the use of flexible straps and an optimal load distribution which
allows a user to avoid unwanted ear loading ensuring user comfort
but with the improved performance of the mask.
[0183] In another embodiment the mask has the strap connection web
characteristics described in the various embodiments above but is
further characterised in having a manifold which not only `floats`
relative to the face contacting parts but has some degree of
relative planar rotation. Therefore, instead of the face sealing
part being formed about and extending from a periphery of the
manifold the face sealing part is connected at a narrowing or waist
formed between the face contacting part and the manifold. The
floating of the manifold relative to the face contacting membrane
provides additional degrees of freedom for the manifold to move
reducing transmission of manifold loadings to the face contacting
part.
[0184] In a further embodiment of the mask described herein, one of
the side sections of the face contacting part are provided with a
thickening in the walls over at least part of the side section. In
another embodiment of the mask described herein, both side sections
of the face contacting part are provided with a thickening in the
walls over at least part of the side sections. The wall thickenings
may be abrupt or gradual according to design requirements. The
thickening may be effected by layering at the region of increased
thickness or by increasing mould thickness/width at the region of
the desired increased thickness. Increasing the thickness of the
side regions of the face contacting part provides increased
stability in the region and specifically introduces into the art
the benefits of a high stiffness wall and its inherent resistance
to load but retaining the benefits of flexibility of the face
contacting material. Since the sealing problems in masks of the
type described herein predominantly occur at the bridge of the nose
and at the upper lip, and to a lesser extent lateral of the nose,
the stiffening of the side contacting parts does not comprise the
rolling flexibility of the contacting part required to maintain the
integrity of the seal. Preferably the thickened portion will have a
maximum thickness falling within the range 0.5 mm-2.0.
[0185] It will be appreciated by persons skilled in the art that
numerous variations and/or modifications may be made to the
invention as shown in the specific embodiments without departing
from the spirit or scope of the invention as broadly described. The
present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive.
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