Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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HOSPITAL BED HAVING AN ADJUSTABLE LENGTH DECK
This application is a division of copending commonly owned Canadian Patent
Application Serial No. 2,304,222 of September 23, 1998.
Background and Summary of the Invention
The present invention relates generally to adjustable beds and more
specifically to
a bed having an improved adjustable foot section.
There are many known bed designs that have adjustable foot sections. On beds
that convert from a planar bed configuration to an upright chair
configuration, the foot section is
generally shortened as the foot section rotates from a horizontal to a
vertical position. There are
also beds having adjustable lengths wherein an attendant physically
repositions the head or foot
section of the bed to the desired length. These designs include a sliding
telescopic foot section as
well as a folding foot section equivalent to a "lazy boy" design. It is also
known to deflate the
foot section of the mattress when converting from a bed to a chair. For short
occupants, there
exists a need for adjustment of the foot prop or board in the chair position
shorter than that
attended by adjusting the length of the foot section.
The ability to adjust the length of the foot section independent of converting
from
a bed to a chair is also important. This would assist in maneuvering the bed
in a confined
locations during patient transport. It also allows the bed length to be
customized to a patient's
size. If a foot prop is provided at the end of the foot section, the
adjustment of the foot section
and the prop would prevent patient migration across the support surface of the
bed. It would also
provide support for the feet to thereby improve the patient's feeling of
security. It could also be
used in the prevention of peripheral neuropathy ("foot drop"). Positioning the
end of the
mattress relative to the patient substantially increases the ability to
provide heel management.
Heel management is wherein the heel is supported by the thigh and the calf and
the heel has
reduced pressure contact with the mattress.
Certain individuals who are confined to bed for an extended period of time are
vulnerable to skin breakdown on the back of the heel. Protection of the skin
in this area is
important if initial indications of tissue failure are observed. If the
breakdown process has
progressed to a point of ulceration, protection of the heel area of the
patient is essential to
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healing.
Reducing or eliminating the time an individual spends in a supine position
will
protect the heel area, although it may increase the risk of skin failure on
other areas of the foot
and body. The current practice for protecting the heel area of a patient while
in the supine
position utilizes foot support to reduce or eliminate pressure and shear on
the back of the heel.
Such support is often provided by placing an ordinary pillow or folded towel
under a calf area of
the patient's legs. Several different foam boot designs are known that strap
to the leg or foot to
reduce the effects of heel pressure. In addition, a conventional mattress is
known in which
removable sections are provided in a foot area.
All of these conventional support methods require a caretaker to add or remove
components from the bed in order to control pressure on the heels of the
patient. Components
which are removed from the bed have the potential to get lost or mislaid.
Components that are
added to the bed provide an extra cost associated with the purchasing,
cleaning, and disposal of
the added components. There is also a cost in time for the caregiver who must
go through
multiple steps to initiate and maintain the support of the device.
The invention of the parent application provides a bed capable of achieving
these
goals. The bed includes a deck having a foot section of a variable length
along the plane of the
foot section. A foot prop is mounted to a first end of the foot section and
extends transverse to
the plane of the foot section. A mattress on the deck has a foot portion of
adjustable length along
the plane of the foot portion and variable thickness transverse to the plane
of the foot portion. A
heel portion of the foot portion of the mattress adjacent the foot prop has a
thickness variable
independent of the thickness of the remainder of the foot portion. The foot
portion of the
mattress includes a plurality of variable length elements separated by a
plurality of variable
thickness elements. The variable length elements are connected to operate
simultaneously and
the variable thickness elements are connected to operate simultaneously and
both operate
independent of the heel portion. Preferably, the heel portion, the variable
length elements and
the variable thickness elements each include one or more bladders which are
inflatable and
deflatable.
To achieve a chair bed, the foot section of the deck is pivotally mounted to
the
remainder of the deck. A first actuator varies the length of the foot section
of the deck, a second
actuator pivots the foot section of the deck and a third actuator varies the
length of the foot
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portion of the mattress. A fourth actuator varies the thickness of the heel
portion of the mattress
and a fifth actuator varies the thickness of the remainder of the foot portion
of the mattress. The
second actuator is deactivated when it encounters a predetermined resistance.
Preferably, this is
during rotation down.
A control system includes an angle sensor and a length sensor connected to the
foot section of the deck. Also, a foot prop sensor is connected to the foot
section of the deck. As
the length sensor senses the position of the end of the bed or it's length,
the appropriate inflation
or deflation of the bladders is made to adjust the length of the foot portion
of the mattress. The
angle sensor cooperates with the foot prop sensor and the control system so
that the foot section
cannot pivot to an angle which will allow egress form the end of the bed
without removal of the
foot prop. This is preferably in the range of 65 to 90 from horizontal.
The foot prop has at least one foot support surface and means are provided for
mounting the foot support surface to the foot section of the deck at different
distances from the
end of the foot section. The mounting means includes one or a pair of sockets
spaced along the
length of the foot section to receive the foot prop. The foot prop may include
a rod received in
the sockets. The rod may be mounted asymmetrical with respect to a pair of
opposed foot
support surfaces. By rotating the foot prop 180 , the foot prop can be mounted
in the same
socket and achieve an adjustment. Alternatively, the rod may be symmetrically
located and the
distance adjusted by selecting one of a pair of sockets spaced along the
length of the second foot
section. The foot prop provides support from the horizontal to a chair
position up to an egress
range of foot section angle.
Another method of shortening the length of the foot support surface beyond
that
which is produced by shortening the foot section of the deck is to not shorten
nor thin the
mattress foot portion when the foot section of the deck is shortened. The foot
portion of the
mattress can then be folded up the support surface of the foot prop. This
decreases the distance
of the foot support surface by the thickness of the mattress foot section.
In accordance with the present invention, the structure which allows
adjustability
of the length of the foot section of the deck includes a first section
connected to the remainder of
the deck and a second section movable relative thereto. Telescopic guides
connect the first and
second sections and the actuator also connects the first and second sections.
Preferably, the
actuator is between a pair of spaced telescopic guides connected to the first
and second sections.
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Also, preferably, the telescopic guides includes three telescopic elements.
The second foot
section has a generally U-shaped cross section encompassing part of the top
and lateral sides of
the first section. The first section is a trapezoid having a large and small
oppose surfaces and the
large surface is the top of the first foot section. The foot section of the
deck has a width smaller
than the width of the remainder of the deck and the foot prop is mounted to
lateral extensions of
the foot section. The width of the foot section with the lateral extensions is
substantially equal to
the width of the remainder of the deck. Bumpers are also mounted to the
lateral extensions.
To size a support surface of the bed to an occupant and provide heel
management,
the bed may be used in the following method. The length of the foot section
with a foot prop
thereon is adjusted until the foot prop is immediately adjacent the foot of an
occupant on the
support surface. The thickness of a portion of the support surface of the
mattress below the heel
of the occupant is reduced. The length of the foot section of the deck and the
foot portion of the
mattress are adjusted simultaneously. The foot section of the deck is adjusted
using the first
actuator, the foot portion of the mattress is adjusted using a second actuator
and the thickness of
one of the portions of the mattress foot portion is reduced using a third
actuator.
A mattress includes a foot portion and a body portion within a ticking. The
foot
portion is secured to the ticking as an adjustable length. The foot section
may either be
corrugated foam of adjustable length or a plurality of bladders which are
inflatable and deflatable
to adjust the length. The bladders need not be secured to the ticking. The
ticking includes at
least one slot and the foot section includes a flap secured thereto and
extends into the slot to
secure the foot section to the ticking. The ticking includes an interior
pocket and the slot is in the
interior pocket. Magnets secured to the ticking for securing the mattress to
the bed may also be
provided in the pockets. A plate is also mounted to the foam displaced from
the flat and straps
are secured to the plate and join the foot section to the foot portion of the
mattress to the body
portion of the mattress. A slip cover is provided encompassing the foot
section to allow easy
movement of the foot portion relative to the ticking.
Other objects, advantages and novel features of the present invention will
become
apparent from the following detailed description of the invention when
considered in conjunction
with the accompanying drawings.
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Brief Description of the Drawings
Fig. 1 is a schematic view of a patient on a bed with the foot section/portion
fully
extended;
Fig. 2 is a schematic view of a patient on a bed with the foot section/portion
adjusted and illustrating the heel management according to the principles of
the present
invention;
Fig. 3 is a bottom view of the foot section of a mattress according to the
principles
of the present invention;
Fig. 4 is a perspective top view of the foot section of the deck according to
the
present invention and connected to the remainder of the deck;
Fig. 5 is a bottom exploded view of a foot section of the deck of Fig. 4;
Fig. 6 is a bottom perspective view of 180 with respect to the respective
view of
Fig. 5 of one section of the deck of Fig. 5;
Fig. 7 is a top perspective view of the detail of the foot prop socket and
safety
switch according to the principles of the present invention;
Fig. 8 is a perspective view of the rotating mechanism according to the
principles
of the present invention;
Fig. 9 is an exploded perspective view of a mattress according to the
principles of
the present invention;
Fig. 10 is a perspective view of a foam foot portion of a mattress according
to the
principles of the present invention;
Fig. 11 is a bottom view of the foot portion of Fig. 10;
Fig. 12 is a side view of the foot portion of Fig. 10 with a cover according
to the
principles of the present invention;
Fig. 13 is a bottom view of the foot portion of Fig. 12;
Fig. 14 is a partial perspective view of the foot end of a ticking for a
mattress
according to the principles of the present invention;
Fig. 15 is a perspective view of the foot section of the deck and a foot prop;
Fig. 16 is a perspective view of a modified foot section of the deck with a
pair of
foot prop sockets;
Fig. 17 is a view of the foot section of the deck shortened and the mattress
foot
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section folded; and
Fig. 18 is a schematic of the fluid controlled circuit for the foot angle
actuator.
Detailed Description of the Preferred Embodiments
As illustrated in the Fig., the bed will be discussed with respect to a deck
10 and a
mattress 20 thereon. As illustrated in Fig. 4, the deck 10 includes a seat
section 12, a thigh
section 14 and a foot section 16 mounted to a frame 18. The deck would also
include, but not
shown, a head section also connected to the frame 18. Since the present
invention is directed
specifically to the foot section 16, the other portion will not be described
in detail. The foot
portion 16 may be used on any deck structure.
The retracting foot section of the present invention can be retracted while
the bed
is in its horizontal bed position. This permits the caregiver to adjust the
overall length of the bed
in either the bed position or the chair position. The overall bed length can
be shortened by about
12-14 inches (30.5-35.5 cm) to facilitate transport of the bed. In other
words, the retracting foot
section reduces the bed length so that the bed can fit into smaller elevators.
The shorter bed also
has a smaller turning radius. The foot section can also be moved to its
retracted position to save
space during storage of the bed.
The retracting foot section of the present invention also decreases patient
migration since the foot prop location may be adjusted to the height of the
patient. Therefore,
the bed size can be customized for the patient. The bed also includes a
shearless pivot linkage as
disclosed in U.S. Patent No. 5,715,548 issued February 10, 1998. The
combination of the
shearless pivot with the retracting foot section and foot prop reduces patient
migration toward the
foot end of the bed as the bed articulates.
The mattress 20 illustrated in Figs. 1 and 2 includes a body support portion
22 and
a foot portion 24. The foot section 24 includes a calf portion 26 which is
variable in length and
thickness and a heel portion 28 which is variable in thickness. One preferred
embodiment of the
mattress foot portion 24 is illustrated in Figs. 1-3 as including a plurality
of bladders. A plurality
of variable thickness bladders 30 is separated by variable length bladders 32.
The heel bladder
28 is separated from one of the variable thickness bladders 30 by a variable
length bladder 32.
The uniaxial variable bladders are produced by gussets in the bladders.
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Referring to Fig. 3, a control line 34 is connected to the foot mattress
portion 24
and by line 36 to the first variable thickness bladder 30. A line 38 at the
other end of the first
bladder 30 is connected to the second bladder 30. Line 40 at the opposite end
of the second
bladder 30 connects the second bladder 30 to the third bladder 30. A control
line 42 is connected
to line 44 of the foot portion 24 which is connected at its other end to the
heel bladder 28. A
control line 46 is connected to the first variable length bladder 32. All of
the variable length
bladders 32 are connected about the periphery of the foot portion 24. A cover
48 for the foot
portion is held together by snaps 50. Preferably, the cover 48 is a slip or a
shear promoting
material, for example, 30 denier ripstop nylon which aids the movement of the
foot section in the
mattress ticking. This removes the shearing between the occupant and the
ticking as the length
of the mattress is changed. A strap 51 is secured to the cover 50 by the snaps
which are rivets
and ties the foot section to an adjacent section 22 of the mattress.
The control lines 34, 42, and 46 are connected to a control module which
selectively inflates and deflates the bladders. An example of the control
module is that taught in
U.S. Patent No. 5,666,681 issued September 16, 1997. From the connection, all
of the variable
thickness bladders 30 are inflated and deflated simultaneously, all of the
variable length bladders
32 are also inflated or deflated simultaneously. Alternatively, each of the
variable length
bladders may be individually controlled with additional control lines or other
flow control
mechanisms. All three types of bladders are independently controlled.
The foot section 16 of the deck includes a first section 52 connected to the
frame
18 and the remainder of the deck and a second section 54 movable along the
plane of the section
52. A foot prop 56 is mounted to the second foot section 54 and extends
transverse to the plane
of the foot sections 52 and 54.
To size the bed to the patient and provide heel management, an occupant is
placed
on the top surface of the mattress 20 as illustrated in Fig. 1 with the calf
of the patient resting on
the foot mattress portion 24. The foot deck section 54 is retracted onto the
deck foot section 52
until the foot prop 56 is adjacent the foot of the occupant as illustrated in
Fig. 2. Simultaneously,
the length adjusting bladders 32 are deflated so that the length of the
portion 26 of the mattress is
decreased, placing the heel of the patient above the heel bladder 28. The heel
bladder 28 is then
deflated, decreasing its thickness such that the interference pressure on the
heel of the patient is
reduced. By independently controlling the length of the foot section of the
deck, the length of
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the foot portion of the mattress, and the thickness of the heel portion of the
mattress, appropriate
adjustment of the length of the bed is possible as well as heel management.
The foot section 16 of the deck may be pivotally connected to the frame so as
to
allow the foot section to drop and to be used in various styles of beds or
chair beds. A separate
and distinct actuator would be provided for the pivotal movement as well as
the articulation of
the other deck sections. This allows adjustment of the foot section for the
length of a patient and
heel management independent of articulation of the deck and mattress as well
as reducing the
length and thickness of the foot portion of the mattress as the deck is
converted to a chair.
The foot section 16 of the deck will be explained with respect to Figs. 4-8.
The
first foot section 52 includes a top wall 58 and a pair of opposed lateral
side walls 60. Mounted
to the bottom surface of top wall 58 by welding for example, are a pair of
guide tubes 62. An
intermediate guide tube 64 is telescopically received with tube 62 and an end
guide tube 66 is
telescopically received in intermediate guide tube 64. As will be discussed
below, the end guide
tube 66 is secured to the second foot section 54. The pairs of telescopic
guide tubes 60, 64 and
66 guide the relative movement of foot section 54 with respect to foot section
52. Plates 68 are
connected between the guide tubes 62 and the bottom surface of the top plate
58. Thus, the foot
section 52 has a trapezoidal shape. This trapezoidal shape with the larger of
the two parallel
surfaces being the top wall 58.
Also mounted to the under surface of the top wall 58 of the foot section is a
hinge
plate 70 which mates with a hinge plate 72 mounted to the deck frame 18. This
pivotally mounts
the foot section 16 of the deck to the frame 18. Mounted between the guide
tube 62 is a pair of
spaced end walls 74 and 76.
The second foot section 54 includes a top wall 78, a pair of side walls 80
extending therefrom, and a pair of bottom walls 82 extending from side walls
80. The top, side,
and bottom walls are made from one continuous piece of material. The second
foot section 54 is
generally U-shaped with bottom flanges 82 forming a C-channel with the side
walls 80 and top
walls 78. Thus, the top and side walls of the foot section 54 encompass or
surrounds a portion of
the top and side walls of the foot section 52. The foot section 54 includes an
end wall 84
connected to the top wall 78, the side walls 80 and the bottom walls 82. Tube
mounting
assembly 86 mounts one end of the guide tube 66 to the end wall 84 of the foot
section 54.
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The end wall 76 of the foot section 52 includes openings 87 and 88, best seen
in
Figs. 4 and 6, between the guide tube 62. An actuator 89 shown in phantom in
Fig. 5 is
connected to end wall 74 and has an input connections. The actuator 89 is
preferably an air
cylinder, and mounting connection 90 on end wall 74 is connected to a control
line (not shown).
The other end of actuator 89 is secured to wall 76 by bracket 92 in the
opening 88. Arm 94
extending from actuator 89 is secured to wall 84 of the second foot section 54
by bracket 96.
The actuator 89 is between the guide tubes 62, 64 and 60. The pair of guide
tubes 62, 64, and 66
provides uniform distribution of forces. Also, the guide tubes support the
weight of the
occupant's feet and minimizes friction between the walls of the foot section
52 and 54. This
prevents binding and rubbing between the foot section 52 and 54.
Plastic wipers 98 are also connected to the underside of top wall 78 of the
foot
portion 54 to protect the sliding joint between the foot sections 52 and 54
and also to prevent the
sheet and mattress from intrusion into the joint and jamming the foot section
adjustment.
The foot section 54 includes lateral extensions 100. Bushing 102 mounts a
bumper or roller 104 to the lateral extension 100. Socket 106 which receives
the foot prop 56 is
also included in the lateral extension 100. Alternatively, a pair of sockets
106 and 107 may be
provided on each extension 100 as shown in Fig. 16. A switch 108 is mounted to
the socket 106
by fastener 110 as illustrated in Fig. 7. Switch 108 indicates the presence of
the foot prop in the
end of the bed and is part of the control system. Alternatively, the switch
108 may be designed
to also sense the presence of pressure on the foot prop produced by the foot
of the occupant of
the bed engaging the foot prop of the occupant of the bed.
Handles 128 are conveniently provided at the foot of the bed connected between
the lateral extensions 100 and the foot section 54. A cover 150 is mounted to
the end wall 84 of
the foot section 54 as shown in Fig. 5. Slots 154 in the top of end wall 84
receives a stop 156
when the foot portion 24 of the mattress is made of foam as illustrated in
Figs. 10-13.
The width W 1 of the foot sections 52 and 54 is substantially the width of the
frame 18 and smaller than the width W2 of the frame 18 with its support
surfaces. This
accommodates side rails (not shown) mounted on the frame 18 in their lowered
or tucked
position as the foot section 16 pivots down. Width W3 of the foot section 16
with the lateral
extensions 100 may be substantially equal to the width W2, since the
extensions will pivot below
the side rails.
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The length of the foot deck section 16 as well as the angle of the foot
section 16
with respect to the frame 18 are determined by length sensor 114 and angle
sensor 116 mounted
to the first foot section 52 at tube 62 by bracket 112. A sensor crank 118 is
mounted to the
length sensor 114 at one end and its other end is mounted to sensor link 120.
The sensor link
120 extends through the opening 87 in the wall 76 and is connected at its
other end to a pivotal
connection 122 to the end wall 84 of the foot section 54. The length sensor
114 may be for
example, a potentiometer wherein the crank 118 and link 120 rotate the
potentiometer with a
change of the length of the foot section 54 with respect to foot section 52.
A link 124 is connected to the angle sensor 116 at a first end by crank 123
and is
pivotally connected at the second end to pivot leg 126 (shown in Fig. 6)
mounted to hinge plate
72 (Fig. 4) which is connected to the deck frame 18. The angle sensor 116 may
also be a
potentiometer to determine the pivotal position of the foot section 16 with
respect to the deck
frame 18.
A pair of links 130 is pivotally mounted at one end to bracket 132 which is
mounted to end wall 76 of the first foot section 52. The other end of links
130 are pivotally
connected between brackets 134 and 136 mounted onto rod 138. The other end of
brackets 136
is pivotally connected by brackets 140 to end wall 142 of the frame 18.
Brackets 144 in the
midsection of rod 138 connect rod 146 of actuator 148 to the rod 138. The
other end of the
actuator 148 is connected to the frame 18. A cover 150 has one end (not shown)
connected to
the frame 18 and its other end connected to brackets 152 which are mounted on
end face 142 of
the frame 18.
The actuator 148 determines the articulation or angular position of the foot
section
16 of the deck. The actuator 148 illustrated in Fig. 18 includes rod 146
connected to piston 147.
A pump 210 is connected to the opposite sides of piston 147 by raising valve
212 and lowering
valve 214. Connected between the pump 210 and the valves 212 and 214 are
filters 216,
restriction 218, and check valves 220. Check valves 220 prevent the
pressurized fluid in the
actuator 148 from flowing back towards pump 210. The other side of piston 147
is connected to
reservoir 222 by lowering return valve 224 and raising return valve 226.
Filter 228 connects the
reservoir 222 to the return valves 224 and 226 and a filter 230 connects
reservoir 222 to the
pump 210.
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To extend the rod 146, electrical valves 212 and 226 are actuated to connect
the
respective sides to the pump 210 and reservoir 222. This raises the foot
section 16. To lower the
foot section 16, and retract the rod 146, electrical valves 214 and 224 are
activated to
respectively connect the opposite sides of the piston 147 to the pump 210 and
reservoir 222. As
a safety feature, relief valve 232 is connected between the output of pump 210
and the reservoir
222. Thus, if the pressure at the output of the pump builds up to an unsafe
level, relief valve 232
provides a flow back to the reservoir 222.
As another safety feature, a relief valve 234 is connected between the output
of
valve 214 and the reservoir 222. Since valve 214 provides the output of the
pump to the piston
147 to lower the foot section, if the pressure in the lowering should exceed
the setting of relief
valve 234, the excess pressure will be relieved back to reservoir 222. This is
a safety feature in
that if the foot section 16 engages an object in its lowering, the piston 147
and rod 146 will stop
moving and pressure will build up on that side of the piston. To prevent
crushing of an object or
a person or part of a person, relief valve 234 will operate. As an alternative
to the relief valve
234, a pressure sensor may also be provided and the valve 214 may be closed or
valve 226
opened. By way of example only and not by way of limitation, whereas the
relief valve 232 for
the pump may be set at 900 PSI (620.5 N/cm2), the relief valve 238 for the
actuator 148 may be
set at approximately 180 PSI (124.1 N/cm2).
The electronics portion 160 of the controller as illustrated in Fig. 4 is
mounted to
the frame 18 below the seat section 12 and the thigh section 14 of the deck.
The controller 160 is
connected to the length sensor 114 by wire 162, to angle sensor 116 by wire
164 and to the prop
sensor switch 108 by wire 166. The sensor crank 118 and sensor link 120 are
hollow or U-
channel and the wire 166 for the prop traverses the foot section 116 through
the channel in the
sensor crank 118 and sensor link 120. As the length sensor 114 sense the
position of the end of
the bed or it's length, the appropriate inflation or deflation of the bladders
is made to adjust the
length of the foot portion of the mattress. The angle sensor 116 in
combination with the foot
prop sensor 108 does not allow the foot section to pivot to an angle, for
example in the range of
65 to 90 from the horizontal, which will allow egress from the end of the
bed without removal
of the foot prop. This prevents the occupant from standing on the foot prop.
Any angle less than
this range will provide foot support in a chair position which is not selected
for ease of egress.
Details of the mattress 20 are illustrated in Fig. 9. Ticking 170 receives the
body
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portion 22 and a foot portion 24. Two examples of each portion are
illustrated. The body
portion 22 could include a foam seat portion 172 and a foam back portion 174.
Alternatively, it
may include a bladder seat section 176 and a bladder back section 178. The
foot section 24
could include a foam foot portion 180 or the bladder foot portion 28, 30 and
32 of Fig. 3. The
control lines 34, 42, and 44 have a bend which corresponds to the juncture of
the back and seat
section of the mattress where a majority of the bending of the mattress
occurs. Any combination
of feet section may be used with any combination of seat and back section.
The body portion 22 and the foot portion 24 fit within the ticking 170. The
ticking 170 is a stretchable, breathable thermal plastic which is impervious
to bacteria. The
seams of the outer ticking of the mattress are formed by continuous ultrasonic
welding.
Therefore, the seams do not require any stitches which can permit fluid
leakage. The
ultrasonically welded seams are impermeable to fluids and bacteria so that the
seams of the
ticking prevent leakage into an interior region of the mattress.
Magnets 182 are provided at the foot end and the head end of the ticking 170
in
interior pockets 184 as illustrated in Fig. 14. These magnets secure the foot
and head end of the
bed to the frame or deck. If the frame is metal, no additional magnets are
needed. If not,
magnets are also provided on the supporting deck or frame.
The details of the foam foot portion 180 is illustrated in Figs. 10-13. A foam
core
186 is corrugated along its length or longitudinal axis. Preferably, the foam
is low-ILD, visco
elastic foam. Its ILD is in the range of 8-12 and is preferably 10. The length
of the foam foot
portion 186 may be, for example, 27 inches (68.58 cm) and is capable of being
shortened to 13.5
inches (34.29 cm). This is an example of one foot portion. The corrugation
allows the foot
portion to diminish in length. Also, the load-ILD allows the foot portion to
compress upon the
weight of the patient. This will help reduce the pressure on the heel. Also,
by providing one of
the valleys adjacent to the foot end of the foot portion 186, the heel may
rest in the valley and
therefore offer a valley or decreased area under the heel.
A portion of the foam 186 adjacent to the remainder of the deck is tapered at
188.
This mates with a tapering 173 of the foam seat portion 172. This is to
accommodate articulation
between the foot portion and the seat or thigh portion. The foot end of the
foam 186 has tapered
corners 190. This allows them to lay adjacent to the foot prop 56.
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Bonded to the bottom of the core 186 adjacent to the deck end is a torque
plate
192, as illustrated in Fig. 11. Prior to bonding, half of a male/female snap
rivets 194 are inserted
through the torque plate 192. An attachment plate 196 is also bonded to the
bottom of the core
186 adjacent to the foot end. Only the cross-half section is bonded and the
ends are left free as
flaps.
The core 186 is provided within a slip cover 198 which includes a zipper 200
as
illustrated in Figs. 12 and 13. The cover 198 preferably is a shear promoting
material, for
example, 30 denier ripstop nylon which aids the movement of the foam foot
portion in the
ticking 170. The flaps of attachment plate 196 extend through slots 202 in the
bottom of the slip
cover 198. This secures the foot end of the core 186 to the slip cover 198.
The other end of the
core 186 is secured within the cover 198 by snap rivets 206 extending through
straps 204 and to
be received in the mating snap 194 of the torque plate 192. The straps 204
secure the foam of
the foot portion 180 to the adjacent seat portion of the mattress within the
ticking 170. The flap
ends of the attachment plates 196 extending through the cover 198 are also
received in slots 208
of pockets 184 as are the magnets 182 of Fig. 14.
As illustrated in Fig. 15, the foot prop 56 has opposed foot support surfaces
55
and 57. The general shape of the foot prop 56 is trapezoidal in cross-section.
The distance D
between the parallel surfaces 55 and 57 may be, for example, 2'/2 inches (6.35
cm). A pair of
rods 59 extends from the bottom surface of the foot prop 56 and is received in
sockets 106 in the
second foot section 54. Although the foot section 16 is shortened or retracted
when the deck
rotates from its flat or planar position to the chair position, for very short
occupants, the foot
prop 56 would still not provide support for the feet of the short occupant. In
such a case, the foot
prop 56 can be rotated 180 with respect to that shown in Fig. 15 such that
the planar surface 57
would be the foot support surface. It would be 2 inches (5.08 cm) closer to
the patient than if
surface 55 was the foot support surface.
As an alternative, a pair of sockets 106 and 107 spaced along the length of
the
foot section may be provided in each extension 100 as illustrated in Fig. 16.
The distance E
between the sockets 106 and 107 again, may be, for example, 2'/2 inches (6.35
cm). This will
allow the foot prop 56 to be moved from sockets 106 to sockets 107 and thereby
shortening the
end by 2'/2 inches (6.35 cm). Rotating the foot prop 56 such that the surface
57 becomes a
support surface, would shorten it an additional 2 inches (5.08 cm). Thus, an
adjustment of 4'/2
CA 02520743 1998-09-23
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inches (11.43 cm) can be obtained using the configuration of Fig. 16.
Additional sockets may be
provided to give additional adjustments.
It should also be noted that although the cross section of the foot prop 56 is
shown
as trapezoidal, any cross sectional configuration which provides a
differential between the two
opposed supporting foot surfaces may be used.
It is important that the foot prop 56 has the parallel surface 55 as a support
surface
when the deck is in its planar position and that it is in sockets 106.
Otherwise, it would overlap
the mattress and prevent the end section from inflating to the appropriate
height. Sensors and
controls can be provided in the sockets 106 and 107 as well as some sensible
indicia on 59 to
indicate which socket it is in and which surface, 55 or 57 is adjacent the
foot. Once this is
sensed, the inflation of the foot section would be prevented until either the
foot prop 56 has been
removed or it is in socket 106 with surface 55 being the foot support surface.
Also, as previously
discussed, the control should not allow the foot section to rotate beyond, for
example, 65 with
respect to the horizontal if the foot prop is mounted in either of the sockets
106 or 107. This
allows the foot prop to be available when the foot section is in a chair
position while preventing
it from being used when the foot section is lowered to permit egress.
Another method of changing the position of the foot support surface of the
foot
prop 56 greater than that achieved by the adjustment of the foot section 16 of
the deck is
illustrated in Fig. 17. While the foot section 16 is adjusted from its
extended to its contracted
shortened position, the mattress foot portion 24 is not shortened nor made
thinner. The non-
shortened portion of the foot portion 24 of the mattress then extends up one
of the support
surfaces of the foot prop 56 and forming a foot support surface. If the
thickness of the foot
portion 24 of the mattress 20 is, for example, five inches (12.7 cm), this
will shorten the length of
the foot section by five inches (12.7 cm). Also, if the reversible foot prop,
as illustrated in Figs.
15 and 16 is used, this would add an additional 7%2 to 9'/2 inches (19.05 to
24.13 cm) of
adjustment.
Although Fig. 17 illustrates further decreasing the length of the deck in the
planar
or total horizontal position, the same adjustment can be made as the foot
section of the deck and
mattress are rotated down from the horizontal position towards the chair
position. The controller
would have to be modified so as to not simultaneously adjust the height or
length of the foot
section of the mattress 24 during the rotational and shortening of the foot
section of the deck.
CA 02520743 1998-09-23
-15-
Although the present invention has been described and illustrated in detail,
it is to
be clearly understood that the same is by way of illustration and example
only, and is not to be
taken by way of limitation. The spirit and scope of the present invention are
to be limited only
by the terms of the appended claims.
