U.S. patent application number 11/099093 was filed with the patent office on 2005-10-20 for wheelchair cushion to transfer heat and moisture.
This patent application is currently assigned to Otto Bock HealthCare LP. Invention is credited to Clover, William M. JR., Heiser, Jeremy.
Application Number | 20050229317 11/099093 |
Document ID | / |
Family ID | 35094691 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050229317 |
Kind Code |
A1 |
Heiser, Jeremy ; et
al. |
October 20, 2005 |
Wheelchair cushion to transfer heat and moisture
Abstract
A cushion adapted to reduce heat and moisture from a wheelchair
user's body, including a cushion member having a compressible
material that permits air and moisture to flow through the cushion
member. The cushion also includes an air and water permeable cover
adapted to receive the cushion member. The cover includes an
interface member having an outer layer formed of a hydrophobic
material, an inner layer formed of a hydrophilic material, and a
spacer layer having fibers positioned between, and generally
perpendicular to, the outer and inner layers.
Inventors: |
Heiser, Jeremy; (Salt Lake
City, UT) ; Clover, William M. JR.; (Buffalo,
MN) |
Correspondence
Address: |
FAEGRE & BENSON LLP
PATENT DOCKETING
2200 WELLS FARGO CENTER
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Otto Bock HealthCare LP
Minneapolis
MN
|
Family ID: |
35094691 |
Appl. No.: |
11/099093 |
Filed: |
April 5, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60559592 |
Apr 5, 2004 |
|
|
|
Current U.S.
Class: |
5/653 |
Current CPC
Class: |
A61G 5/12 20130101; A47C
27/144 20130101; A61G 5/1043 20130101; A61G 7/05715 20130101; A47C
27/15 20130101; A47C 27/148 20130101; A47C 7/742 20130101 |
Class at
Publication: |
005/653 |
International
Class: |
A47C 027/15; A47C
027/22 |
Claims
What is claimed is:
1. A cushion adapted to reduce heat and moisture from a wheelchair
user's body, comprising: a cushion member including a compressible
material that permits air and moisture to flow through the cushion
member; and an air and water permeable cover adapted to receive the
cushion member, the cover including an interface member having: an
outer layer formed of a hydrophobic material; an inner layer formed
of a hydrophilic material and positioned substantially parallel to
the outer layer; and a spacer layer constructed of a compressible
hydrophobic material and having fibers positioned between, and
generally perpendicular to, the outer and inner layers.
2. The cushion of claim 1, wherein the interface member has a
varying thickness.
3. The cushion of claim 1, wherein the cushion member has a varying
thickness.
4. The cushion of claim 1, further comprising a support member,
wherein the support member is more rigid than the cushion member
and cover, to provide stability for a wheelchair user.
5. The cushion of claim 4, wherein the support member includes an
aperture to allow air and moisture to flow through the support
member.
6. The cushion of claim 4, wherein at least a portion of the
support and cushion members have complementary shapes.
7. The cushion of claim 1, wherein the spacer layer is attached to
the outer layer.
8. The cushion of claim 1, wherein the spacer layer is attached to
the inner layer.
9. The cushion of claim 1, wherein the cover further includes an
air and moisture permeable backing member attached to the interface
member.
10. The cushion of claim 1, wherein the cushion is configured to
interface with at least one of the wheelchair user's back, arm,
head, and leg.
11. The cushion of claim 1, wherein at least one major surface of
the cushion is non-planar.
12. A wheelchair, comprising: a frame; at least two wheels attached
to the frame; a seat attached to the frame; and a cushion,
positioned with respect to the frame so as to be adjacent to a
portion of a wheelchair user's body when the user is sitting in the
wheelchair, the cushion including: a cushion member including a
compressible material that permits air and moisture flow through
the cushion member; and an air and water permeable cover adapted to
receive the cushion member and having an air and water permeable
interface member.
13. The wheelchair of claim 12, wherein the interface member
includes: an outer layer formed of a hydrophobic material and
extending along at least a substantial portion of a surface of the
cover positioned adjacent to the user's body; an inner layer formed
of a hydrophilic material and positioned substantially parallel to
the outer layer; and a spacer layer constructed of a compressible
hydrophobic material and having fibers positioned between, and
generally perpendicular to, the outer and inner layers.
14. The wheelchair of claim 12, further comprising a support member
that is attached to the cushion, wherein the support member is more
rigid than the cushion member and cover.
15. The wheelchair of claim 12, wherein the cushion is configured
to interface with at least one of the wheelchair user's back, arm,
head, and leg.
16. A method for reducing heat and moisture from a body surface of
a wheelchair user seated in a wheelchair, comprising: providing an
air and moisture permeable cushion including: a cushion member
having a compressible material that permits air and moisture to
flow through the cushion member; and a cover adapted to receive the
cushion member and engage a portion of the wheelchair user's body;
and positioning the cushion between a portion of the wheelchair
user's body and the wheelchair.
17. The method of claim 16, wherein providing the cushion further
comprises providing an interface member for the portion of the
cover engaging a portion of the wheelchair user's body, the
interface member having: an outer layer formed of a hydrophobic
material; an inner layer formed of a hydrophilic material and
positioned substantially parallel to the outer layer; and a spacer
layer constructed of a compressible hydrophobic material and having
fibers positioned between, and generally perpendicular to, the
outer and inner layers.
18. The method of claim 17, wherein providing the cover further
comprises attaching the spacer layer to the inner layer and outer
layer.
19. The method of claim 16, wherein positioning the cushion
includes positioning the cushion between the wheelchair user's back
and the wheelchair.
20. The method of claim 16, wherein positioning the cushion
includes positioning the cushion between at least one of the
wheelchair user's arm, leg or head and the wheelchair.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/559,592, filed Apr. 5, 2004 and entitled
Wheelchair Cushion to Transfer Heat and Moisture, which is hereby
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to wheelchair cushions, particularly
cushions that provide for improved heat and moisture transfer from
the person in the wheelchair.
BACKGROUND OF THE INVENTION
[0003] It is well known that the skin of people who are confined to
wheelchairs is vulnerable to potentially injurious consequences
resulting from the long periods of time that they sit in their
wheelchairs. Specifically, sitting in the same position for long
periods of time subjects portions of a person's body to pressures,
increased temperatures and moisture resulting from perspiration.
Heat and moisture are thought to be significant factors in skin
tissue stress and breakdown. The relative contribution of these
factors as causative agents for pressure sores is not fully
understood. However, it has been shown that moisture is the
greatest influence in the formation of superficial pressure sores.
Such conditions can combine to compromise the integrity of a
person's skin, potentially resulting in irritation, decubitis
ulcers (commonly known as bedsores), and other dermal ulcers. Left
untreated, nearby tissue begins to die, eventually resulting in an
ulcer that can reach a person's bone, leaving an open cavity with
resulting secondary infections that can cause serious illnesses or
even death.
[0004] It is not unusual for a person confined to a wheelchair to
spend up to 14 to 16 hours a day sitting in their chair. Depending
upon a person's capacity for movement, several portions of a
person's body, including the back, forearms, and head may be in
contact with the wheelchair for most or all of that time every day.
Typically, those parts of the body that are exposed to long term
contact with the chair are rested on a cushion of some sort to
reduce and distribute the pressure to which the skin is subjected.
While a cushion may be an effective way to reduce and more
uniformly distribute skin pressure, a cushion may do very little to
remove heat or moisture. Therefore, these parts of the body are
still potentially vulnerable to a reduction in skin integrity,
unless heat and moisture can be effectively removed from the
person's skin.
[0005] Some attempts have been made to relieve the harmful high
temperature and moisture conditions on people's skin. For example,
Sunrise Medical sells a seat back with a cushioning pad that
includes a spacer fabric that covers a foam pad to allow air flow
around their foam pad. What is needed, however, is a cushioning
device that uses substantially the entire cushion to help draw
moisture and heat away from the wheelchair user's body parts that
are in contact with the wheelchair as well as distribute pressures
more evenly across the user's body. Such an invention would reduce
the risk of such injuries as decubitis ulcers.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a cushion adapted to
reduce heat and moisture from a wheelchair user's body. The cushion
includes a cushion member with a compressible material that permits
air and moisture to flow through it and an air and water permeable
cover adapted to receive the cushion member. The cover includes an
interface member having an outer layer, an inner layer positioned
substantially parallel to the outer layer, and a spacer layer
positioned therebetween. The outer layer includes a hydrophobic
material, the inner layer includes a hydrophilic material, and the
spacer layer includes a compressible hydrophobic material that has
fibers positioned between, and generally perpendicular to, the
outer and inner layers. The cushion can be configured to interface
with any one of the wheelchair user's back, arm, head, and leg.
[0007] The current invention is also directed to a method for
reducing heat and moisture from a body surface of a wheelchair user
seated in a wheelchair. The method includes the steps of providing
an air and moisture permeable cushion that includes a cushion
member having a compressible material and a cover adapted to
receive the cushion member and engage a portion of the wheelchair
user's body, such as the back, head, arm or leg. The cushion is
then positioned between the portion of the wheelchair user's body
and the wheelchair. The cover includes an outer layer formed of a
hydrophobic material, an inner layer formed of a hydrophilic
material and positioned substantially parallel to the outer layer,
and a spacer layer constructed of a compressible hydrophobic
material and having fibers positioned between, and generally
perpendicular to, the outer and inner layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an isometric view of a wheelchair that includes
cushions in accordance with an embodiment of the invention.
[0009] FIG. 2 is an isometric view of a back rest cushion in
accordance with one embodiment of the invention.
[0010] FIG. 3 is a cutaway view, showing the layers of material
included, of the back rest cushion shown in FIG. 2.
[0011] FIG. 4 is back view of a cushion member of the back rest
cushion showing an alternative support member.
[0012] FIG. 5 is an isometric view of a cushion member in
accordance with one embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to FIG. 1, a wheelchair 10 typically includes a
frame 12, which provides the primary structure and support for the
wheelchair 10. Wheelchair 10 has a primary wheel 14 located on each
of an opposing left side 11 and right side 13 of wheelchair 10.
Each primary wheel 14 is fixed to the frame 12 at a center point of
primary wheel 14 towards a back side 17 of the wheelchair 10.
Primary wheels 14 can be rotated about an axle to propel the
wheelchair 10 in either a fore or aft direction by the application
of an external force, from a wheelchair user or another person or,
alternatively, with the use of a mechanized drive system. In
addition, wheelchair 10 may include a caster wheel 16, coupled to
frame 12 of each of the left side 11 and right side 13 and towards
the bottom of a front side 19 of wheelchair 10. The caster wheels
16 are significantly smaller than the primary wheels 14 and are
used primarily to facilitate steering and movement of the
wheelchair 10 and contribute to the stability of the wheelchair 10
while the wheelchair is moving or at rest.
[0014] Wheelchair 10 has a seat 20 and a backrest 22 coupled or
integrated to frame 12, which substantially form a chair to accept
and support a portion of the wheelchair user's torso and legs while
the user is sitting in wheelchair 10. In addition, wheelchair 10
may have at least one foot rest 24, at least one arm rest 26, and a
head rest 28, all coupled to or integrated with frame 12, designed
to accept and support the user's feet and lower legs, arms, and
head, respectively. The wheelchair 10 could have a number of other
features, such as a self-contained propulsion system, including
those that have electric motors coupled to drive systems; various
frame structures, including variations on the foot, arm, and head
rests; different wheel configurations, including variations in the
size, type and number of wheels; and other optional accessories or
combinations of accessories (none of which are shown).
[0015] The wheelchair 10 may include a back rest cushion 30,
attached or positioned on a front side of back rest 22, an arm rest
cushion 32, attached or positioned on a top side of each arm rest
26, and a head rest cushion 34, attached or positioned on a front
side of head rest 28. It is to be understood that while one
embodiment includes back rest cushion 30, two arm rest cushions 32
and head rest cushion 34, any combination of cushions can be used
without departing from the scope of the invention. For example, one
particular wheelchair user may require only a back rest cushion 30;
another user may require a back rest cushion 30 and either one or
two arm rest cushions 32; still another user may require a back
rest cushion 30 and a head rest cushion 34. It is to be further
understood that a particular user may require or desire to have a
cushion for other portions of the body, including, for example,
cushions for a portion of the user's legs.
[0016] The back rest cushion 30 is positioned between the back rest
22 and the user when the user is sitting in the wheelchair 10, so
that the front surface 31 is positioned closer to the wheelchair
user's back than the back surface 33. Back rest 22 is shaped to
accept a portion of a human torso. The back rest 22 may have one or
more openings of any size and shape along the back rest 22. Back
rest 22, in one embodiment, is made out of a hard polymeric
material, but any suitable material may be used, including
materials such as leather, synthetic leathers, metallic or
composite materials, or fabrics. It is to be understood that back
rest 22 may be made of many different materials and be of different
sizes and shapes.
[0017] Referring to FIGS. 2 and 3, the cushion 30 has a front
surface 31 and an opposing back surface 33, which together include
the majority of the surface area of back rest cushion 30. Cushion
30 has a thickness 32 defined as the distance between the front
surface 31 and the back surface 33. The thickness 32 of back rest
cushion 30 may or may not be uniform across the front surface 31.
Cushion 30 may include a edge surface 35, which is located between
the front 31 and back 33 surfaces along the perimeters of those
surfaces 31, 33. The cushion 30 may be shaped and sized so that,
when it is located on a front side of back rest 22, it covers
approximately the entire front side of the back rest 22. The actual
shape and size of the cushion 30 may vary depending upon the type
of wheelchair or other factors. For example, the cushion 30 could
actually be made of more than one similarly constructed cushions
positioned in front of back rest 22, which may or may not be
connected to or adjacent each other. Alternatively, the back rest
cushion 30 may be sized to cover only a portion of the front of
back rest 22.
[0018] The cushion 30 may not be attached to the back rest 22, but
may instead be positioned between the user and the back rest 22.
Alternatively, the cushion 30 may be either permanently or
removably attached to the back rest 22 or any other acceptable part
of wheelchair 10 using clips, snaps, hook and loop fasteners, ties,
or any other acceptable attachment device or method, or combination
of attachment devices and methods.
[0019] In one embodiment, back rest cushion 30 includes a cover 60
and a cushion member 38. The cover 60 is designed to enclose and
protect the cushion member 38, and to interface with that portion
of the wheelchair user's body which contacts the back rest cushion
30. The cover 60 includes an access 62, which allows the cushion
member 38 to be placed inside of or removed from the cover 60.
Access 62 may include a zipper (not shown) which can be used to
close the access once the cushion member is enclosed within the
cover 60. The area around the access may be constructed from
similar materials as those used to construct the interface member
36 or backing 40. Alternatively, any suitable materials may be
used, including any nylon or similar materials.
[0020] Cover 60 includes an interface member 36, which extends over
most or all of the front surface 31 of the cover 60. In addition,
interface member 36 may extend over parts or all of the edge
surface 35 and the back surface 33. Alternatively, cover 60 may
include a backing 40, which forms at least a part of the back
surface 33 of cover 60, although it may be adjacent any surface or
combination of surfaces. Backing 40 is constructed of a nylon mesh
material with a mesh pattern large enough to provide for adequate
air and moisture transfer. If the cover 60 includes backing 40,
backing 40 is attached to interface member 36 by a suitable
structure such as stitching (not shown). Alternatively, backing 40
may be attached to interface member 36 via snaps, buttons,
adhesives or any other suitable mechanism. It is to be understood
that while the interface member 36 and backing 40 are described as
being attached to form a cover 60, it is possible that the
interface member 36 is not directly attached the backing 40, but
that the interface member 36 may be attached to the cushion member
38.
[0021] Interface member 36 may be constructed of a multi-layered
material such as Dri-lex.RTM. lining material manufactured by
Faytex Corporation. This material includes a hydrophobic outer
layer 42, located on at least part of the exterior surface of the
interface member 36. The outer layer 42 can be constructed of a
variety of hydrophobic polymer materials such as a woven
polypropylene or other acceptable material, and is constructed so
that it has a mesh pattern or other suitable configuration with
enough vacancies within the outer layer 42 to allow moisture and
air to travel freely through it. The outer layer 42 has a thickness
of approximately one millimeter, although that thickness may vary
substantially and may be non-uniform across the surface of the
outer layer. In addition, the interface member 36 may also include
an inner layer 46.
[0022] The inner layer 46 is constructed of an hydrophilic material
such as Hydrofil.RTM. Nylon, manufactured by Honeywell, Inc.,
although any suitable hydrophilic material may be used. Inner layer
46 has a mesh-type pattern that allows air and water to pass freely
through it. Inner layer 46 is approximately the same size and shape
as the outer layer 42 and is positioned substantially parallel to
the outer layer 42. In one embodiment, the inner layer 46 has a
relatively uniform thickness--usually less than one millimeter.
Alternatively, the inner layer 46 may vary in thickness in a
similar fashion as the outer layer 42.
[0023] Interface member 36 may also include a spacer layer 44
located between the outer layer 42 and the inner layer 46. The
spacer layer 44, in one embodiment, is constructed of a hydrophobic
material, although any suitable material may be used. Spacer layer
44 is positioned so that its fibers are generally perpendicular,
that is, within about 45 degrees of perpendicular, to both the
outer layer 42 and the inner layer 46. The spacer layer 44 has a
thickness of about six millimeters, although that thickness may
vary substantially in alternative embodiments. Further, the
thickness of spacer layer 44 may or may not be uniform across the
interface member 36. The perpendicularity and the hydrophobic
nature of the fibers that make up the spacer layer 44 allow
moisture to move freely from the hydrophobic layer 42 to the
hydrophilic layer 46. Further, the spacer layer 44 provides a
cushioning effect which aids in the distribution and minimization
of contact pressure on that portion of the wheelchair user's body
which contacts the back rest cushion 30.
[0024] Spacer layer 44 is woven to both the outer layer 42 and the
inner layer 46 so that the three layers are attached to each other
and substantially form the interface member 36. It is to be
understood, however, that the spacer layer 44 may alternatively be
attached to the outer layer 42, the inner layer 46, or both by
using an adhesive, heat bonding, or any other suitable attachment
device or process. It is to be further understood, that the spacer
material may simply be positioned between the outer layer 42 and
the inner layer 46 without actually being attached to either
layer.
[0025] In one embodiment, interface member 36 has a varying
thickness. For example, the thickness of interface member 36 may
vary across the front surface 31 of cover 60 to provide more
cushioning in specific areas for the wheelchair user's body.
Alternatively, the interface member 36 may have a differing
thickness on differing surfaces of cover 60, if it should form
other surfaces of cover 60. For example, interface member 36 may be
generally thicker on the front surface 31 than it is the edge
surface 35 and/or the back surface 33.
[0026] Cushion member 38 includes a cushion portion 37, constructed
out of a breathable material that provides cushioning and is
sufficiently permeable to allow moisture and air to flow freely
through it. In one embodiment, the cushion portion 37 is
constructed of spherical particles of closed cell foam,
approximately 0.25 inches in diameter. These particles are packed
together and are attached, adhered, bonded, or otherwise connected
together at their tangent points or surfaces, leaving vacancies
between the particles that allow air and moisture to flow through
the foam in all directions. An example of such a foam is Brock.RTM.
foam, manufactured by Brock USA.
[0027] While the particles in one embodiment are spherical in
shape, alternatively they may be of any particular shape that
allows for vacancies between particles when closely concentrated
together. For example, a particle may have a regular shape, such as
a dodecahedron or a icosahedron, or it may have any irregular shape
that provides such vacancies when the particles are connected to
each other at their tangent points or surfaces. While in one
embodiment particles have a diameter of approximately 0.25 inches,
any particle size, larger or smaller, which will allow for
sufficient vacancies between the particles when they attached to
one another is acceptable. In addition, the particles may be of
varying, non-uniform sizes.
[0028] Referring to FIG. 5, cushion member 38 has a generally
rectangular, three-dimensional shape, although alternatively, the
shape of cushion member 38 may vary. For example, a front surface
50 of cushion member 38 may have concave curvature (not shown) or
have multiple angles to approximate a concave surface so as to
conform at least partially to a portion of the user's body.
Alternatively, the front surface 50 may be non-planar with respect
to its opposing surface over some or all of its surface to provide
support for various parts of the user's body. In addition, the
cushion member 38 may have rounded and/or tapered corners or be
irregularly shaped as shown in FIG. 5.
[0029] While cushion member 38 may consist solely of cushion
portion 37, it may also include other elements. For example,
cushion member 38 may include a support member 39 as shown in FIG.
4. Support member 39 may be positioned along a substantial portion
of the cushion member 38. Support member 39 may be constructed of
an air and moisture permeable material similar in properties to
those of cushion portion 37. Alternatively, support member 39 may
be constructed of any polymeric, metallic or other acceptable
material that does not have substantial permeability. In such an
instance, support member 39 are formed to include at least one
vacancy 41 so that air and moisture may move through the cushion
member 38. It is to be understood that support member 39 may be
more rigid than cushion portion 37 to provide improved support for
the user's body, or less rigid to provide increased cushioning for
part of the user's body. Support member 39 may be positioned along
or attached to a single surface of cushion portion 37. If support
member 39 is attached to cushion portion 37, it may be attached
through the use of an adhesive, attachment devices integrated into
support member 39, interlocking attachment mechanisms integrated
into both cushion portion 37 and support member 39, or any
attachment mechanism including clips, screws, or other acceptable
fasteners.
[0030] While support member 39 is shown to be a single structure
attached to a back surface of cushion portion 37, support member 39
may be located anywhere with respect to cushion portion 37
including being integrated with cushion portion 37. Further,
support member 39 may include multiple structures of the same or
varying shapes and materials, which may be located anywhere on or
within cushion portion 37, including on any surface or combination
of all or part of the surfaces of cushion portion 37.
[0031] The back rest cushion 30, with its collection of components
designed to encourage air flow and moisture evacuation away from
the user's skin, provides a significant improvement in those areas
over the state-of-the-art cushion. However, the cushion of the
preferred embodiment, with its interface member 36 and cushion
member 38 each providing cushioning, has been shown to provide
surprisingly better minimization and distribution of pressure in a
pressure mapping test conducted against a state-of-the-art "Back 1"
back rest cushion manufactured by Otto Bock, Inc. (part number
476D10=RA15-17).
[0032] The pressure mapping test was conducted by using pressure
sensors placed in a grid along the back rest cushion to determine
the cushions' performance as determined by three parameters:
contact surface area, peak pressure and pressure dispersion. The
wheelchair was then positioned at various inclined positions and
pressure measurements were taken to calculate the three
parameters.
[0033] The back rest cushion 30 showed consistently higher contact
surface area performance than the Back 1 cushion. A higher contact
surface area is desirable, as a larger contact area indicates that
contact pressures are less likely to be concentrated in certain
areas. The average reading at different angles of incline showed
about an 8% increase in contact area.
[0034] Likewise, the back rest cushion 30 of the present invention
showed improvements in its peak pressure and pressure dispersion
readings. On average, the cushion 30 of the present invention had
about 3% lower peak pressure on the cushion 30 at different incline
angles and about 7.25% better pressure dispersion than was found
with the Back 1 cushion. Therefore, the cushion 30 of the present
invention reduces the contact pressure and provides improved
pressure distribution across the contact surface than the
state-of-the-art cushion.
[0035] While the details of the invention have been described with
respect to the back rest cushion 30, it is to be understood that
the invention may be adapted to the other cushions such as the head
rest cushion 34 or the arm rest cushion 32 that may be incorporated
in a wheel chair. While the present invention has been described
with reference to preferred embodiments, workers skilled in the art
will recognize that changes may be made in form and detail without
departing from the scope of the invention.
* * * * *