U.S. patent application number 10/456661 was filed with the patent office on 2003-10-23 for breathing assistance apparatus.
This patent application is currently assigned to Fisher & Paykel Healthcare Limited. Invention is credited to Gradon, Lewis George, Haycock, Mark Joseph, Mahon, Daniel, McAuley, Alastair Edwin, Nightingale, Chris Earl, Smith, Nicholas Charles Alan.
Application Number | 20030196659 10/456661 |
Document ID | / |
Family ID | 27484393 |
Filed Date | 2003-10-23 |
United States Patent
Application |
20030196659 |
Kind Code |
A1 |
Gradon, Lewis George ; et
al. |
October 23, 2003 |
Breathing assistance apparatus
Abstract
A CPAP system for supplying humidified gases to a user. Various
interfaces are described for delivering the gases. A mask cushion
including a deformable cushion and a thin sheath is described. A
forehead rest with a horizontal pivot is attached to the mask. An
outlet vent to reduce the noise from exhausted carbon dioxide is
described. A mouthpiece is also described with an outlet diffuser
including Heat Moisture Exchanger Material.
Inventors: |
Gradon, Lewis George;
(Auckland, NZ) ; Smith, Nicholas Charles Alan;
(Auckland, NZ) ; McAuley, Alastair Edwin;
(Auckland, NZ) ; Haycock, Mark Joseph; (Auckland,
NZ) ; Nightingale, Chris Earl; (Auckland, NZ)
; Mahon, Daniel; (Auckland, NZ) |
Correspondence
Address: |
TREXLER, BUSHNELL, GIANGIORGI,
BLACKSTONE & MARR, LTD.
105 WEST ADAMS STREET
SUITE 3600
CHICAGO
IL
60603
US
|
Assignee: |
Fisher & Paykel Healthcare
Limited
15 Maurice Paykel Place, East Tamaki
Auckland
NZ
|
Family ID: |
27484393 |
Appl. No.: |
10/456661 |
Filed: |
June 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10456661 |
Jun 6, 2003 |
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10297951 |
Mar 25, 2003 |
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10297951 |
Mar 25, 2003 |
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PCT/NZ01/00110 |
Jun 14, 2001 |
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Current U.S.
Class: |
128/201.26 |
Current CPC
Class: |
A61M 16/06 20130101;
A61M 16/0488 20130101; A61M 16/0069 20140204; A61M 16/0816
20130101; A61M 2016/0039 20130101; A61M 16/0493 20140204; A61M
16/0495 20140204; A61M 16/065 20140204; A61M 2205/42 20130101; A61M
16/109 20140204; A61M 16/0057 20130101; A61M 16/0616 20140204; A61M
16/1045 20130101; A61M 16/1065 20140204; A61M 16/0638 20140204;
A61M 16/0825 20140204; A61M 16/1095 20140204; A61M 16/0066
20130101; A61M 16/0666 20130101; A61M 16/0683 20130101; A61M
16/0622 20140204; A61M 16/08 20130101; A61M 16/16 20130101 |
Class at
Publication: |
128/201.26 |
International
Class: |
A62B 018/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2000 |
NZ |
505154 |
Jun 14, 2000 |
NZ |
505156 |
Dec 20, 2000 |
NZ |
509039 |
Mar 12, 2001 |
NZ |
510520 |
Claims
The invention claimed is:
1. A mouthpiece for delivering a supply of gases to a user from a
breathing assistance apparatus comprising: engagement means adapted
to in use juxtapose said mouthpiece in or about the oral cavity of
a user and substantially seal thereabouts, a conduit adapted to
fluidically communicate a breathing assistance apparatus with the
oral cavity of a user, and diffusing means adapted to be in fluid
communication with said conduit and located substantially within,
and delivering said supply of gases in a substantially diffused
manner to, the oral cavity of a user.
2. A mouthpiece for delivering a supply of gases to a user as
claimed in claim 1 wherein said conduit includes an inlet, in use
fluid communication with said supply of gases, and an outlet in
fluid communication with said inlet, said diffusing means including
a diffusing material engaged over said outlet in use through which
said gases pass and are thereby discharged in a diffused
manner.
3. A mouthpiece for delivering a supply of gases to a user as
claimed in claim 2 wherein said diffusing material comprises a
portion of porous material in use through which said gases
pass.
4. A mouthpiece for delivering a supply of gases to a user as
claimed in claim 3 wherein said porous material is material chosen
from those known to have heat and moisture exchanging
properties.
5. A mouthpiece for delivering a supply of gases to a user as
claimed in claim 4 wherein said material substantially allows
moisture to pass inwardly from said conduit to, but prevents egress
outwardly from, the oral cavity of a user.
Description
FIELD OF INVENTION
[0001] This invention relates to patient interfaces particularly
though not solely for use in delivering CPAP therapy to patients
suffering from obstructive sleep apnoea (OSA).
BACKGROUND OF THE INVENTION
[0002] In the art of respiration devices, there are well known
variety of respiratory masks which cover the nose and/or mouth of a
human user in order to provide a continuous seal around the nasal
and/or oral areas of the face such that gas may be provided at
positive pressure within the mask for consumption by the user. The
uses for such masks range from high altitude breathing (i.e.,
aviation applications) to mining and fire fighting applications, to
various medical diagnostic and therapeutic applications.
[0003] One requisite of such respiratory masks has been that they
provide an effective seal against the user's face to prevent
leakage of the gas being supplied. Commonly, in prior mask
configurations, a good mask-to-face seal has been attained in many
instances only with considerable discomfort for the user. This
problem is most crucial in those applications, especially medical
applications, which require the user to wear such a mask
continuously for hours or perhaps even days. In such situations,
the user will not tolerate the mask for long durations and optimum
therapeutic or diagnostic objectives thus will not be achieved, or
will be achieved with great difficulty and considerable user
discomfort.
[0004] U.S. Pat. No. 5,243,971 and U.S. Pat. No. 6,112,746 are
examples of prior art attempts to improve the mask system U.S. Pat.
No. 5,570,689 and PCT publication No. WO 00/78384 are examples of
attempts to improve the forehead rest.
[0005] Where such masks are used in respiratory therapy, in
particular treatment of obstructive sleep apnea (OSA) using
continuance positive airway pressure (CPAP) therapy, there is
generally provided in the art a vent for washout of the bias flow
or expired gases to the atmosphere. Such a vent may be provided for
example, as part of the mask, or in the case of some respirators
where a further conduit carries the expiratory gases, at the
respirator. A further requisite of such masks is the washout of gas
from the mask to ensure that carbon dioxide build up does not occur
over the range of flow rates. In the typical flow rates in CPAP
treatment, usually between 4 cm H.sub.2O to 20 cm H.sub.2O, prior
art attempts at such vents have resulted in excessive noise causing
irritation to the user and any bed partners.
[0006] Various approaches have been developed in the prior art to
attempt to reduce the noise when CPAP therapy is provided. For
example, in PCT Patent Application No. WO98/34665 it has been
proposed that the vent include a resilient plug with rounded edge
apertures to reproduce noise. However, this is not entirely
effective in eliminating the extra noise created by a vent at the
mask.
[0007] In common with all attempts to improve the fit, sealing and
user comfort is the need to avoid a concentrated flow of air at any
portion of the respiratory tracts. In particular with oral masks or
mouthpieces it is a disadvantage of prior art devices that the oral
cavity may become overly dehydrated by use of the device, causing
irritation and possible later complications.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to attempt to
provide a patient interface which goes some way to overcoming the
abovementioned disadvantages in the prior art or which will at
least provide the industry with a useful choice.
[0009] Accordingly in one aspect the invention may broadly be said
to consist in a device for delivering a supply of gases to a user
comprising:
[0010] a patient interface, in use in fluid communication with said
supply of gases, engaging with said user and thereby supplying said
gases to said user.
[0011] outlet means associated with said patient interface
including a plurality of outlet vents formed in a flexible portion
of said outlet means, said outlet means in use passing a
substantial portion of the expired gases of said user.
[0012] Preferably said patient interface is a mouthpiece.
[0013] Alternatively said patient interface is a nasal mask.
[0014] Preferably said mouthpiece comprises:
[0015] a vestibular shield having an inner surface and an outer
surface, said vestibular shield having a predetermined height which
will overlap said user's teeth and gums when positioned in the
mouth vestibule of said user;
[0016] gases passageway means extending from said outer surface of
said vestibular shield to said inner surface of said vestibular
shield for allowing the passage of said gases through said
mouthpiece; and
[0017] extra-oral sealing means associated with said gases
passageway which may be adjusted into one of two configurations, a
first condition when said mouthpiece is inserted into said user's
mouth being substantially unengaged with said user's face, and a
second condition when correctly positioned in said user's mouth
being substantially engaged with said user's face and under
compression thereupon.
[0018] Preferably said nasal mask comprises restraining means
attached to or around the head of said user, a hard body portion
having an inlet receiving said supply of gases and an open section,
sealing means attached to said body portion substantially contoured
to the facial contours of said user and a receiving means attached
to said hard body which in use engages with said restraining
means.
[0019] Preferably said flexible portion of said outlet means
comprises a sleeve having a plurality of outlet vents, said sleeve
attaching over said outlet means, said sleeve composed of a
substantially flexible material, said outlet means having a outlet
aperture and in use said sleeve located on said outlet means such
that said outlet aperture matches up with said plurality of outlet
vents thereby in use passing a substantial portion of the expired
gases of said user.
[0020] Alternatively, said outlet means is either integral or in
fluid communication with said patient interface, said outlet means
being composed substantially of a single material, and said
flexible portion comprising a portion of said outlet means in which
the thickness of said material is substantially less than, and
therefore substantially more flexible than, the remainder of said
outlet means.
[0021] To those skilled in the art to which the invention relates,
many changes in construction and widely differing embodiments and
applications of the invention will suggest themselves without
departing from the scope of the invention as defined in the
appended claims. The disclosures and the descriptions herein are
purely illustrative and are not intended to be in any sense
limiting.
[0022] The invention consists in the foregoing and also envisages
constructions of which the following gives examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] One preferred form of the present invention will now be
described with reference to the accompanying drawings in which;
[0024] FIG. 1 is a block diagram of a humidified continuous
positive airway pressure (system) as might be used in conjunction
with the present invention,
[0025] FIG. 2 is an illustration of the nasal mask in use according
to the preferred embodiment of the present invention,
[0026] FIG. 3 is a side elevational view of the mouthpiece as being
used by a patient,
[0027] FIG. 4 is a perspective view from above of the
mouthpiece,
[0028] FIG. 5 is a perspective view from one side and from an
inward direction of the mouthpiece of FIG. 4,
[0029] FIG. 6 is a cross-section of the mouthpiece of FIG. 4,
[0030] FIG. 7 is a cross-sectional view of the mouthpiece of FIG. 4
and a user with the mouthpiece in place to demonstrate the location
and positioning thereof in relation to the main features of the
user's anatomy,
[0031] FIG. 8 is a perspective view of the mouthpiece with the
outer flap in place,
[0032] FIG. 9 is a perspective view of the outer flap bent
back,
[0033] FIG. 10 is a cutaway view of the mouthpiece with the outer
flap in use,
[0034] FIG. 11 is a perspective view of the outer flap including
the ventilation apertures and moisture barrier,
[0035] FIG. 12 shows the outlet vent sleeve installed on the
elbow,
[0036] FIG. 13 shows the outlet vent sleeve in isolation,
[0037] FIG. 14 shows the elbow in isolation,
[0038] FIG. 15 shows the one piece elbow outlet vent interior,
[0039] FIG. 16 shows the one piece elbow outlet vent exterior,
[0040] FIG. 17 shows a cross section of the mouthpiece with a
dispersing filter,
[0041] FIG. 18 shows a perspective view of the mask with
cushion,
[0042] FIG. 19 is a cuttaway view of the mask showing the
cushion,
[0043] FIG. 20 is a cuttaway view of the periphery of the outer
membrane,
[0044] FIG. 21 is a cuttaway view of the periphery of the mask body
portion,
[0045] FIG. 22 shows a make with the forehead rest on a user,
and
[0046] FIG. 23 shows the forehead rest in isolation.
[0047] The present invention provides improvements in the delivery
of CPAP therapy. In particular a patient interface is described
which is quieter for the user to wear and reduces the side leakage
as compared with the prior art. It will be appreciated that the
patient interface as described in the preferred embodiment of the
present invention can be used in respiratory care generally or with
a ventilator but will now be described below with reference to use
in a humidified CPAP system. It will also be appreciated that the
present invention can be applied to any form of patient interface
including, but not limited to, nasal masks, oral masks and
mouthpieces.
[0048] With reference to FIG. 1 a humidified Continuous Positive
Airway Pressure (CPAP) system is shown in which a patient 1 is
receiving humidified and pressurised gases through a patient
interface 2 connected to a humidified gases transportation pathway
or inspiratory conduit 3. It should be understood that delivery
systems could also be VPAP (Variable Positive Airway Pressure) and
BiPAP (Bi-level Positive Airway Pressure) or numerous other forms
of respiratory therapy. Inspiratory conduit 3 is connected to the
outlet 4 of a humidification chamber 5 which contains a volume of
water 6. Inspiratory conduit 3 may contain heating means or heater
wires (not shown) which heat the walls of the conduit to reduce
condensation of humidified gases within the conduit. Humidification
chamber 6 is preferably formed from a plastics material and may
have a highly heat conductive base (for example an aluminium base)
which is in direct contact with a heater plate 7 of humidifier 8.
Humidifier 8 is provided with control means or electronic
controller 9 which may comprise a microprocessor based controller
executing computer software commands stored in associated
memory.
[0049] Controller 9 receives input from sources such as user input
means or dial 10 through which a user of the device may, for
example, set a predetermined required value (preset value) of
humidity or temperature of the gases supplied to patient 1. The
controller may also receive input from other sources, for example
temperature and/or flow velocity sensors 11 and 12 through
connector 13 and heater plate temperature sensor 14. In response to
the user set humidity or temperature value input via dial 10 and
the other inputs, controller 9 determines when (or to what level)
to energise heater plate 7 to heat the water 6 within
humidification chamber 5. As the volume of water 6 within
humidification chamber 5 is heated, water vapour begins to fill the
volume of the chamber above the water's surface and is passed out
of the humidification chamber 5 outlet 4 with the flow of gases
(for example air) provided from a gases supply means or blower 15
which enters the chamber through inlet 16. Exhaled gases from the
patient's mouth are passed directly to ambient surroundings in FIG.
1.
[0050] Blower 15 is provided with variable pressure regulating
means or variable speed fan 21 which draws air or other gases
through blower inlet 17. The speed of variable speed fan 21 is
controlled by electronic controller 18 (or alternatively the
function of controller 18 could carried out by controller 9) in
response to inputs from controller 9 and a user set predetermined
required value (preset value) of pressure or fan speed via dial
19.
[0051] Nasal Mask
[0052] According to a first embodiment of the present invention the
patient interface is shown in FIG. 2 as a nasal mask. The mask
includes a hollow body 102 with an inlet 103 connected to the
inspiratory conduit 3. The mask 2 is positioned around the nose of
the user 1 with the headgear 108 secured around the back of the
head of the patient 1. The restraining force from the headgear 108
on the hollow body 102 and the forehead rest 106 ensures enough
compressive force on the mask cushion 104, to provide an effective
seal against the patient's face.
[0053] The hollow body 102 is constructed of a relatively
inflexible material for example, polycarbonate plastic. Such a
material would provide the requisite rigidity as well as being
transparent and a relatively good insulator. The expiratory gases
can be expelled through a valve (not shown) in the mask, a further
expiratory conduit (not shown), or any other such method as is
known in the art.
[0054] Mask Cushion
[0055] Referring now to FIGS. 18 and 19 in particular, the mask
cushion 1104 is provided around the periphery of the nasal mask
1102 to provide an effective seal onto the face of the user to
prevent leakage. The mask cushion 1104 is shaped to approximately
follow the contours of a patient's face. The mask cushion 104 will
deform when pressure is applied by the headgear 1108 to adapt to
the individual contours of any particular user. In particular,
there is an indented section 1150 intended to fit over the bridge
of the user's nose as well as a less indented section 1152 to seal
around the section beneath the nose and above the upper lip.
[0056] In FIG. 19 we see that the mask cushion 1104 is composed of
a inner foam cushion 1110 covered by an outer sealing sheath 1112.
The inner cushion 1110 is constructed of a resilient material for
example polyurethane foam, to distribute the pressure evenly along
the seal around the user's face. The inner cushion 1110 is located
around the outer periphery 1114 of the open face 1116 of the hollow
body 1102. Similarly the outer sheath 1112 may be commonly attached
at its base 1113 to the periphery 1114 and loosely covers over the
top of the inner cushion 1110.
[0057] In the preferred embodiment shown in FIGS. 19-21 the bottom
of the inner cushion 1110 fits into a generally triangular cavity
1154 in the hollow body 1102. The cavity 1154 is formed from a
flange 1156 running mid-way around the interior of the hollow
body.
[0058] The outer sheath 1112 fits in place over the cushion 1110,
holding it in place. The sheath 1112 is secured by a snap-fit to
the periphery 1114 of the hollow body. In FIGS. 20-21 the periphery
1114 is shown including an outer bead 1158. The sheath 1112
includes a matching bead 1159, whereby once stretched around the
periphery, the two beads engage to hold the sheath in place.
[0059] Forehead Rest
[0060] In the preferred embodiment of the present invention the
nasal mask 2102 includes a hinged forehead rest 2106 (seen in FIGS.
22 and 23). The attachment of the forehead rest 2106 to the hollow
body 2102 effectively allows the forehead rest 2106 to move freely
in proximity to the user but with no lateral movement.
[0061] In one form shown in FIG. 23, pins 2130 are provided mounted
on a base 2132 attached to the hollow body 2102. These pins 2130
are co-axial within cylinders 21-31 mounted on a bridge member
2136.
[0062] At the top end 2142 (around the user's forehead) of the
bridge member 2136 harnessing slots 2138 are provided which allow
straps from the headgear to be inserted to secure the mask to the
headgear. For the user's comfort one or more resilient cushions
2140 are provided underneath the top end 2142 of the bridge member
2136, which rest on the forehead of the user. The cushion 2140
might be constructed of silicon or any foam materials as is known
in the art for providing cushioning.
[0063] For example the forehead rest 2106 described previously may
include a weakened section 2130 at its base 2132 which allows the
joining member 2136 to pivot from the hollow body 2102. The bridge
member extends up to the forehead of the user. In a further
alternative the mask may include a vertical upwardly extending
inlet. In this case the member 2136 is hinged at its base 2132 to
either side of the inlet passage. Again the member would then
extend to the forehead.
[0064] Alternatively any well-known form of hinge can be used to
provide the pivoting action.
[0065] Mouthpiece
[0066] Now with reference to a further inlet embodiment of the
present invention the patient interface 2 is shown in FIGS. 3 to 10
as a mouthpiece. In this embodiment, the mouthpiece 50 includes a
vestibular shield 49 being a generally flat and generally
rectangularly-shaped member in front elevation having a curved
profile that reflects the curvature of a user's jaw and in turn the
curvature of the labial vestibule region. A gases passageway
extends through the vestibular shield from an inlet 51 to an outlet
52 in much the same way as with the earlier embodiments. In the
preferred embodiment the inlet 51 is provided by a flattened
oval-shaped connector 53. The outlet 52 has an even more laterally
extended flattened oval shape 54. The major differences between the
mouthpiece 50 and the embodiments described above are provided on
the inner face of the vestibular shield. Most prominently, the
mouthpiece 50 includes a tongue depressor 55 extending from the
inner face of the vestibular shield 49. The operation of the tongue
depressor will be described further on with reference to FIG. 5 The
tongue depressor includes a vertical stiffening flange 56 centrally
located on its upper surface and extending from the gases outlet
52. In use gases flow easily around the stiffening flange 56
effectively bifurcating the gases outlet 52. The tongue depressor
55 further includes a pair of vertically extending spacers 57 which
in use may abut against the roof of the wearer's mouth and ensure
that the tongue cannot completely block the air passageway. In the
mouthpiece 50 the sealing effect of the vestibular shield 49
against the lips of the user is enhanced by providing teeth
abutments of significantly increased thickness than the raised area
20 of the earlier embodiments. In particular, an upper teeth
abutment 58 and a lower teeth abutment 59 are provided, with the
lower teeth abutment 59 protruding further from the inner face of
the vestibular shield 49 than the upper teeth abutment 58. This
difference serves to match the typical over-bite of most users. The
abutments 58 and 59 are not required to be wider than the gases
outlet 52.
[0067] A notch 60 is provided centrally in the upper edge of the
vestibular shield 49 to accommodate the upper frenal attachment. A
slight bead 61 is provided around the edge of the vestibular shield
49 for user comfort, with the vestibular shield 49 otherwise being
very thin for additional suppleness.
[0068] Referring particularly to FIG. 6, in its preferred form the
mouthpiece 50 is preferably formed by over-moulding a soft and
supple material part 70 over a stiffer material part 67. These can
generally be termed the shield part and the passageway-forming
insert. The passageway-forming insert preferably includes a pair of
upper and lower vertical flanges 63 and 64 to fully engage within
the supple material. The passageway-forming insert 67 includes the
vertically extending stiffening flange 56 of the tongue depressor
55, together with a curved planar portion 71 forming the backbone
of the tongue depressor 55. The vertically extending spacers 57 are
of the soft and supple material and are part of the over-moulding
70, a.sctn.are the upper and lower teeth abutments 58 and 59.
[0069] Referring now to FIG. 7, use of the mouthpiece according to
FIGS. 4 to 6 is depicted. With the present mouthpiece 50, the upper
and lower lips 85, 86 are further distended by the abutment action
of the abutments 75, 76 against the upper and lower teeth 87, 88
respectively, thus forming a seal of greater pressure between the
lips 85, 86 and the upper and lower portions respectively of the
vestibular shield 49. A lower face 77 of the tongue depressor 55
impinges if necessary on the upper surface 72 of the tongue 85 and
retains the tongue in the lower portion of the mouth. This ensures
a clear gases outlet 52 from the gases passageway through the
vestibular shield. The vertically extending spacers 57, if forced
by pressure from the tongue, will engage against the roof of the
user's mouth and maintain a clear air passageway. This stops the
sleeping patient unconsciously blocking the oral passageway and
reverting to nasal breathing.
[0070] Referring now to FIG. 8 of the present invention is
illustrated including an extra-oral sealing flap 110. The flap 110
in its natural bias is tapered, the wide open end of which is
shaped to conform to the facial contours around the outside of the
mouth of a user. The narrow end joins to a cylindrical section,
which is designed to slide over the inlet port 114 of the
mouthpiece 112. While this is one method of attachment the flap 100
might also be constructed as an integral part of the mouthpiece
112. The flap 110 needs to be constructed of flexible material,
therefore materials such as silicone rubber can be employed to
fashion the flap.
[0071] The outer flap 110 is seen in FIG. 9, in a bent back
position. It will be appreciated that when the mouthpiece 112 is
being inserted into the mouth of a user, the outer flap 110 is
intended to be in this bent back position to aid insertion. Prior
to insertion, the outer flap is bent back by simply pressing on its
outer periphery 116, until it snaps into the bent back position, in
which it will stay unaided.
[0072] In FIG. 10 we see the outer flap 110 in use with the
mouthpiece 112 in the mouth 117 of a user 120. Once correctly
positioned in the mouth 116, the outer flap 110 may be adjusted
into its operational position by pressing on its outer periphery
116 until it snaps back to press against the outside of the mouth
118. Due to the relative position of the vestibular shield 122 and
the outer flap 110, the outer flap 110 is unable to fully reach its
natural bias and thereby inflicts a compressive force on the
outside of the mouth 118.
[0073] It will be appreciated that as well as providing a
substantially airtight seal the addition of the outer flap provides
enough compressive force on the mouth to keep the mouthpiece and
conduit in place without the need for straps. This allows the
administering of CPAP therapy to be considerably less obtrusive
than traditional methods.
[0074] In a further additional improvement shown in FIG. 11, the
outer flap 300 is shown in perspective. Included are ventilation
apertures 302, 303 either side of the gases port 304, which are
surrounded by a ridge 306 acting as a moisture barrier. The
apertures 302,303 are provided such that any excess moisture
leaking from the mouth will migrate to the apertures where they may
evaporate. Small vents in the conduit may be used to direct small
amounts of pressurised gas at the apertures to aid evaporation. The
ridge 306 is included to ensure that no moisture migrates further
into the sealing region 308, as this would be detrimental to the
sealing properties of the flap.
[0075] Interface Connection
[0076] Attention is now directed to FIG. 3. It has been found that
an additional factor in the effectiveness of any patient interface
2, is the manner in which the interface is connected to the
breathing circuit 41. The weight of the breathing circuit 41, and
any attempted movement of one other of the breathing circuit 41 and
the interface 2 relative to the other, is one of the largest
influences tending to dislodge the interface 2. It must be noted
that the interface 2 must remain in position and maintain a seal
during all sleep, when the user has no muscle tone.
[0077] The connection 40 as provided in the present invention
between the breathing circuit 41 and the interface 2 decouples the
interface 2 from the breathing circuit 41. As a result, the
connection 40 is effective in reducing the forces placed on the
interface 2 by the breathing circuit 41 when the user moves around
during sleep. In the preferred sleeping position, the breathing
circuit 41 is laid across the chest 43 of the user, and may be
secured to the user's bed clothes or sleeping garments. The
breathing circuit 41 is preferably laid on the chest of the user to
take the weight of the breathing circuit 41 off of the interface
2.
[0078] To connect between the gases outlet 14 which is vertical
when the user is laying on his or her back and the breathing
circuit 41 which is generally horizontal, an L-shaped elbow 45 is
incorporated in the connection 40. The elbow 45 may be incorporated
in the interface 2. The elbow 45 is formed at a right angle and
provides a positive pressure on the interface 2. The elbow 45 may
include a swivel joint and may be disconnected from gaseous outlet
42. The connection 40 further includes an extremely flexible
connecting tube 46 provided between the elbow 45 and the breathing
circuit 41. The connecting tube 46 is preferably connected to the
breathing circuit 41 by a swivel joint 48 for reasons described
herein. The breathing circuit 41, while flexible, will necessarily
be stiff enough to maintain its integrity over comparatively long
tuns, while the connecting tube 46, being only a short length, for
example 10 centimetres, merely has to span between the user's mouth
and chest, and can thereby be made in a manner that would not be
suitable for long runs. Furthermore, as a result of the short
length of the connecting tube 46, the connecting tube 46 does not
need to incorporate significant insulation or heating capability.
The connecting tube 46 may be formed from a thin plastic membrane
supported over a helical or double helical or corrugated supporting
ribs. In such a case, the support makes the connection tube 46
laterally flexible and resistant to torsion. The elbow swivel joint
45 allows for movement of the connection tube 46 relative to the
interface 2. The swivel joint 48 allows for movement of the
connection tube 46 relative to the breathing circuit 41. It is to
be understood that one or both of the swivel joints 45, 48 could be
eliminated, but the preferred embodiment includes swivel joint
48.
[0079] Outlet Vent
[0080] The present invention will now be described with reference
to the various different embodiments previously described. In order
to reduce the noise caused by expiratory gases being expelled from
the patient interface 2, the present invention is illustrated in
FIGS. 12 to 17 with the elbow connector (previously designated as
45) including an outlet vent. It would be appreciated by one
skilled in the art that the elbow connector as described herein
will be equally applicable to all proceeding embodiments and all
other forms of patient interface for delivering CPAP therapy.
[0081] Referring particularly now to FIGS. 12 to 14, the elbow
connector is illustrated including a flexible sleeve 400 which fits
overtop of the elbow connector. The sleeve 400 is preferably
constructed of silicon) but it will be appreciated by one skilled
in the art that a number of other flexible materials will be
equally applicable. The sleeve 400 includes locating indents 402
which once installed on the elbow connector match up with and lock
into locating notches 404 on the elbow connector. The location is
necessary so that the outlet aperture 406 in the elbow connector
always matches up with the outlet vents 408 in the outlet sleeve
400. This then prevents the undesirable situation where the sleeve
could slip and the outlet vents 408 not match up with the outlet
aperture 406 with resulting consequences to the patient.
[0082] Referring now to FIGS. 15 and 16, the present invention is
shown with a one-piece elbow. In this case the elbow is preferably
constructed of either "Hytrel" plastic or polycarbonate. In this
fashion the elbow connector is manufactured to have a thin portion
410 surrounding the outlet vents 412 in comparison to the remainder
of the elbow connector which is considerably thicker. The
properties of the material chosen for the elbow connector are such
that its flexibility is dependent on its thickness. Therefore in
the thin section 410 the elbow connector is relatively flexible and
in the remainder is relatively rigid. Accordingly the outlet vents
412, which are also rounded on their periphery are formed in a
flexible portion, and therefore achieve the desirable low noise
properties when expiratory gases are vented therethrough.
[0083] Flow Diffuser
[0084] Referring now particularly to the use of mouthpieces, a
further improvement is shown in FIG. 17. It is documented that when
CPAP therapy is delivered to patients they often complain of drying
of the airways and resulting irritation and discomfort. In
particular when a concentrated airflow of under humidified gases
flows past the oral or nasal cavities, or the airway of the user
then drying and irritation may occur. Accordingly the present
invention as illustrated in FIG. 17 includes a mouthpiece with a
flow diffuser 500.
[0085] As described in the preceding embodiments, the mouthpiece
sits with a vestibular shield 502 between the gums 504 and the lips
506 of a user. An outer flap 508 provides compressor force on the
lips 506 to keep the mouthpiece in place in the user's mouth. Again
the mouthpiece includes a tough depressor 510 extending into the
user's oral cavity.
[0086] In the preceding embodiments the delivered gases would flow
through passageway 512 in the mouthpiece, causing a relatively
concentrated flow of gases to flow through the oral cavity and down
the airway. With the flow diffuser 500 fitted overtop of the
passageway 512 the flow is defused over the much larger area of the
diffuser 500, and therefore both the speed and side effects are
reduced.
[0087] Alternatively the space between the passageway 512 and the
diffuser 500 could be filled with a Humidity Moisture Exchange
(HME) material. This would allow moisture through on the
inspiratory flow put prevent it passing out an expiration. This
would further prevent against the patient's passageways drying out.
Further, if the HME material was in the form of foam, then it might
also act as the diffuser 500. It will also be appreciated that the
HME material could be used in the space 516 all the way out to the
elbow connector (not shown) to maximise its effect.
[0088] It will be appreciated that by providing such a system the
present invention effectively minimises the noise generated by the
outward flow of expiratory gases from the mask. The present
invention requires little or no maintenance. The present invention
also provides a flow diffuser for use with the mouthpiece, which
reduces any side effects of orally delivered CPAP therapy and
improves user comfort.
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