Note: Descriptions are shown in the official language in which they were submitted.
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ZONED CELLULAR CUSHION
Background of the Invention
This invention relates in general to inflatable
mattresses and cushions, and more particularly to an
inflatable mattress or cushion having normally isolated
zones and a series of valves for placing its normally
isolated zones selectively in communication with each
other and with atmosphere.
Those individuals who are confined to wheelchairs run
the risk of tissue breakdown and the development of
pressure sores, which are extremely dangerous and
difficult to cure. Typically much of the individual's
weight concentrates in the regions of the ischia, that is
at the bony prominences of the buttocks, and unless
frequent movement occurs, the flow of blood to the skin
tissue in these regions decreases to the point that the
tissue breaks down. Cushions which are especially
designed for wheelchairs exist for reducing the
concentration of weight in the region of the ischia, and
these cushions generally seek to distribute the user's
weight more uniformly over a larger area of the buttocks.
Cellular cushions provide the most uniform
distribution of weight and thus provide the greatest
protection from the occurrence of pressure sores. These
cushions have an array of closely spaced air cells which
project upwardly from a common base. Within the base the
air cells communicate with each other, and thus all exist
at the same internal pressure. Hence, each air cell
exerts essentially the same restoring force against the
buttocks, irrespective of the extent to which it is
deflected. U. S. Patent 4,541,136 shows a cellular
cushion currently manufactured and sold by ROHO, Inc., of
Belleville, Illinois, for use on wheelchairs.
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In a sense the typical cellular cushion provides a
highly displaceable surface which tends to float the
user. While this reduces the incidence of pressure sores,
it detracts from the stability one usually associates with
a seating surface. Most of those confined to wheelchairs
have little trouble adjusting to the decrease in
stability, but for those who have skeletal deformities,
particularly in the region of the pelvis and thighs, and
for those who lack adequate strength in their muscles,
lesser stability can be a source of anxiety. A variation
of the ROHO cellular cushion addresses this problem with
totally isolated zones and also cells of varying height.
By varying the pressure between zones, one can accommodate
for skeletal deformities while still maintaining
satisfactory protection against pressure sores. U.S.
Patent 4,698,864 shows a zoned cellular cushion with cells
of varying height.
Typically, a zoned cellular cushion has a separate
filling stem and valve for each of its zones. The user
simply opens the valve of each stem and introduces air
into the zone for that stem, usually with a hand pump, and
then releases the air from the zones until the desired
posture is achieved. In a more sophisticated arrangement,
a hose kit connects a single pump to a manifold which in
turn is connected to the several valves through separate
hoses. These hoses are fitted with separate hose clamps
so that the air from the pump may be directed to the cells
of the individual zones independently, and likewise the
air can be released from them independently, all by
manipulating the clamps. The hoses of the hose kit lie
externally of the cushion and may become entangled in
components of a wheelchair. Furthermore, by reason of
their remote location, the hose clamps are difficult to
manipulate.
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Even more traditional inflatable cushions derive
advantages from zoning, that is from being divided into
zones or compartments which can be isolated from each
other to accommodate skeletal deformities.
Serial No. 07/778,450 describes a valve for a zoned
inflatable cushion such that access to all of the zones is
cut-off simultaneouly because the valve is in a flap which
is part of the cushion base and all of the access channels
run through the flap.
The present invention is an improvement on the prior
cushions which utilize a series of hoses to inflate the
cushion in that it positions the bodies of the hoses
within the periphery of the cushion and gathers the ends
of all of the hoses in close proximity adjacent to one
edge so that they do not become entangled in the
wheelchair and are readily accessible to the user. It
also is an improvement on Serial No. 07/778,450 in that
the zones can be adjusted simultaneouly or selectively.
The present invention also resides in providing
access to the cushion zones from beneath the cushion. A
further advantage of the present invention is in providing
access to the underside of the cushion and also to each
cell of the cushion whereby pressure in each cell of the
cushion can be monitored from a remote location.
This invention is equally appliable to inflatable
mattresses, but will be described in connection with a
wheelchair cushion.
These and other objects and advantages of the present
invention will become apparent hereinafter.
Description of the Drawings
In the accompanying drawings which form part of the
specification and wherein like numerals and letters refer
to like parts wherever they occur:
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Fig. l is a top perspective view of a cushion
embodying the invention;
Fig. 2 is a bottom plan view of the cushion shown in
Fig. l;
Fig. 3 is a fragmentary sectional view taken along
lines 3-3 of Fig. 2;
Fig. 4 is a fragmentary sectional view taken along
lines 4-4 of Fig. 2.
Fig. 5 is a fragmentary perspective view of a method
of interrupting fluid flow through the manifold and the
channels.
Fig. 6 is a top plan view of a modification of the
invention; and
Fig. 7 is a sectional view taken along line 7-7 of
Fig. 6.
Detailed Description
Referring now to the drawings (Fig. l), A designates
a cellular cushion which is highly flexible and is
designed for use on an underlying supporting surface, such
as, the seat of a wheelchair or the seat of a conventional
chair. Being cellular, the cushion A distributes the
weight of its occupant generally uniformly over the entire
area of the buttocks and thereby dissipates the pressures
resulting from the supported weight at the ischia, that
is, at the bony prominences of the buttocks. It further
has the capacity to position and stabilize the user.
The cushion A includes (Fig. l) a base 2 and air
cells 4 which project upwardly from the base 2. Both the
base 2 and the air cells 4 are preferably molded or
otherwise formed from highly flexible neoprene. The base
2 is rectangular and the cells 4 are arranged on it in
longitudinal rows and transverse rows, with each cell 4
occupying both a longitudinal row and a transverse row.
The cells 4 are further arranged in zones, typically, four
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zones r, s, t, and u. The zones r and s lie side by side
at the front of the cushion A, whereas the zones t and u
exist side by side at the rear of the cushion A. The
right zones r and t are separated from the left zones s
and u along a longitudinal axis x-x, whereas the front
zones r and s are separated from the rear zones t and u
along a transverse axis y-y. More or less zones and
differing arrangements of those zones may be employed.
Within the base 2, the cells 4 of the zone r
communicate with each other, so that all exist at the same
internal pressure irrespective of how far they are
depressed. The same holds true with regard to the cells 4
of the zone s, the cells 4 of the zone t, and the cells 4
of the zone u. However, the cells 4 of the zone r
normally do not communicate with the cells 4 of the zones
s, t and u, or in other words the cells 4 of the zone r
are normally isolated from the cells of the remaining
zones s, t and u. Likewise the cells 4 of the zone s are
normally isolated, as are the cells of the zones t and u.
Thus, the cells 4 of each zone r, s, t and u collectively
enclose a separate compartment.
Connected to each of the zones r, s, t and u are fill
tubes 20, 21, 22 and 23, respectively. These are flexible
and tubular in cross-section. These terminate in close
proximity to each other adjacent to, but outwardly of one
edge of the cushion A. Preferably they come out from
beneath the front edge of the cushion A so they are
accessible to the wheelchair user. The free ends of the
tubes 20, 21, 22 and 23 are connected to a manifold 24 to
which is connected a fill nozzle 25 having a shut off
valve 26 (Fig. 1). The fill tubes 20, 21, 22 and 23 are
all connected to the zones r, s, t and u through the
underside of the cushion A. By passing beneath the
cushion A, the fill tubes 20, 21, 22 and 23 provide
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access to the zones r, s, t and u for pressure monitoring
devices. Also, there can be tubes or similar monitoring
devices connected to each of the individual cells 4
through the underside of the cushion A so that a complete
dynamic pressure profile of the patient can be taken at a
remote location at any given point in time.
Positioned on each of the tubes 20, 21, 22 and 23
adjacent to the manifold 24 are cut-off clamp type hose
valves 30. The valves 30, as shown, comprise a base 31
having an upstanding lock post 32. A spring arm 33 is
connected to and overlies the base 31. The arm 32 has a
knife edge nose 34 which is designed to engage notches 35
on the post 32 to lock the arm 33 to the post 35 when in
cut-off position. Cut-off members 36 and 37 are on the
base 31 and the arm 33 respectively. The cut-off members
36,37 are aligned, and when the nose 34 and lock notches
35 are engaged, move toward each other to force the tube
sides together into linear sealing alignment to thereby
block the tube and close off flow of air or other fluid
through the fill tubes 20, 21, 22 and 23. The fill tubes
20, 21, 22 and 23 pass through the arm 33 and the lock
post 32 by means of ports 38, 38a, respectively. These
manually operated valves can be replaced with electrically
operated solenoid valves which would permit sequential
operation. If no valves are desired, then the air flow
can be sealed off by folding the tubes 20, 21, 22 and 23
back on themselves to cause them to buckle as shown in
Fig. 5.
In the structure of Fig. 5, the flexible tubular
channels 20, 21, 22, 23 and manifold 24 are bent back
toward the cushion A to crimp the channels 20, 21, 22 and
23 and form linear seals therein. The manifold 24 is held
in its bent back position by the combination of the rigid
nozzle 25 and a flexible retaining strap 27 which has one
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end fixed to the base 2 and the other end has a suitable
fastening means 28, such as a snap fastener or a hook and
loop fastener sold under the trademark VELCRO. When using
this type retainer, it is desirable to use individual fill
tubes 40 for each of the zones to provide for selective
individual adjustment of the zones.
Operation
In order to prepare the cushion A for the user, the
valves 20, 21, 21 and 23 are opened. This places the
interiors of the cells 4 for the four zones r, s, t and u
in communication through the mainfold 24. Air is pumped
into the cushion through the valve 26. Since the cells 4
of the zones r, s, t and u are in communication through
the manifold 24, all of the cells 4 are inflated. The
cells 4 reach a state of equilibrium in a short time.
Enough air is pumped into the cushion A to exceed the
requirements for supporting the user. The valve 26 is
then closed and the pump removed.
Next the overinflated cushion A is placed on the
supporting surface upon which it is to rest when
supporting the user, and that could be a wheelchair seat
or the seat of a traditional chair. The user then sits
upon the cushion A in the location he expects to assume
and slowly releases air from the filling valve 26 to
immerse the user. As the air is released, the user's
buttocks sink deeper and deeper into the array of air
cells 4, and they tend to envelope and assume the contour
of the buttocks. Enough air is released to bring the
region of the ischia to within about l/2 inch of the base
2. Of course, as the air flows out of the cushion A, all
of the cells 4 remain at essentially the same internal
pressure, because they are all interconnected through the
open manifold 24. When the user achieves the desired
immersion, the filling valve 26 is closed.
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While immersed in the cells 4 of the cushion A, the
user moves or is moved by others to the posture desired to
be maintained for an extended period, and this causes a
redistribution of air amongst the cells 4 of the several
zones r, s, t and u. In time, the cells 4 of the several
zones r, s, t and u reach equilibrium, that is to say the
flow between the zones r, s, t and u ceases. At this
time, the individual valve~ 20, 21, 22 and 23 are closed
to prevent air from flowing between the zones r, s, t and
u.
The isolated zones r, s, t and u impart stability to
the cushion A, and this serves to maintain the user in the
selected posture. Thus, if the user attempts to assume a
different posture, he will encounter greater resistance
from cells 4 of one of more of the zones r, s, t and u,
and they will urge the user back to the initial posture.
The capacity to maintain a selected posture or to urge the
user to such a posture is ~articularly useful with users
who suffer from spinal deformities and for those whose
muscles have atrophied.
To further adjust the position of the user on the
cushion, the valve 26 is opened and the individual cut-off
valve 20, 21, 22 and 23 to the zone which is to be
adjusted also is opened. Air can be added to or bled from
the selected zone selectively without involving the other
zones.
An alternative construction provides for individual
fill valves 40 on each of the zones r, s, t and u. The
valves 40 make it easier to test each quadrant or zone for
leaks in the assembly process and also to separately fill
or bleed each zone.
Thus, the sectors r, s, t, and u can be filled
separately through the individual closure valves 40 or
= ~
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through selective opening and closing of the cut-off
valves 20, 21, 22 and 23.
Figs. 6 and 7 show a modification of the invention in
which four independent cells 45 are positioned on the base
46 and have individual fill channels 47, 48, 49 and 50
which are connected to a manifold 51 having a fill nozzle
52. The channels 47, 48, 49 and 50 may be on the top or
the bottom of the base 46, but must be within the confines
of the cushion and the ends should terminate in close
proximity to each other outside one edge of the base 46.
Each of the channels 47, 48, 49 and 50 has a clamp or
shut off valve 53 positioned between the edge of the
cushion 46 and the manifold 51.
If clamps 53 are not used, the manifold 51 is bent
back on itself and locked down to the base 46 to close off
and seal the tubes 47, 48, 49 and 50 as shown in Fig. 5.
If this variation is used, independent fill tubes 54 may
be positioned in each of the cells 45 of the cushion.
This invention is intended to cover all changes and
modifications of the example of the invention herein
chosen for purposes of the disclosure which do not
constitute departures from the spirit and scope of the
invention.
