Note: Descriptions are shown in the official language in which they were submitted.
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
BED ASSEMBLY
The present invention relates to a bed assembly and to a mattress support.
Modem hospital beds are generally designed to be configurable into a variety
of
profiles. Typically, they are provided with a plurality of sections which can
be tilted or
otherwise moved to change a patient's position on the bed. For example, they
are usually
provided with a back rest section which can pivot from a substantially flat
position to a
raised sitting position, with a thigh rest section wliich can be pivoted from
a substantially
flat position to a knee raised position, and with leg rest section coupled to
the thigh rest
section and able to be raised with the thigh rest section while keeping the
feet in a lower
position or while keeping the feet in a raised position.
Beds having such functions are well known in the art and generally work
satisfactorily. However, there are concerns in the operation of such beds,
relating
particularly to the fact that when one of the bed portions rotates upwardly
relative to an
adjacent bed section there is a compression effect on the patient, which can
be particularly
unpleasant. Furthermore, such beds can cause discomfort to any patient kept on
the bed
for prolonged periods, at worst leading to the onset of bed sores and other
ailments.
The present invention seeks to provide an improved bed assembly and mattress
support.
According to an aspect of the present invention, there is provided a
substantially
rigid mattress support for a bed including a back rest section which is curved
in a
'20 transverse direction to the mattress support.
It has been found that a curved back rest support improves patient comfort. It
is
understood the reason for this is that the traditional mattress support, being
flat, generates
particular pressure points at the patient's areas of greatest pressure, that
is the protruding
parts of a patient's body. A mattress, although being resilient, can only
partially mitigate
- this disadvantage. A curved back rest support conforms more closely with the
curves of a
patient's back so is able to provide more even support. Furthermore, it has
been
discovered that a curved back rest of this nature provides a greater contact
area, thereby
spreading the pressure of a patient's weight more evenly and reducing high
pressure areas
which can lead to the development of bed sores and other ailments.
In the preferred embodiment the mattress support is formed of a plurality of
substantially rigid mattress support sections which are movable relative to
one another,
including a backrest section, a thigh rest section and a leg rest section.
There may also be
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
2
provided a seat section, although in some embodiments the seat section may
simply be a
hinged area between the baclc rest section and the thigh rest section.
With a curved back rest section, the mattress support can be arranged such
that the
lowermost part of the back rest section, that is its central portion, moves
away from the
seat section as it pivots upwardly. This has an important advantage as during
such a
motion, which raises the patient to a sitting position, the patient's rear
tends to lengthen as
a result of stretching. Thus, the action of moving the lowermost part of the
back rest
section away from the seat section effectively increases the length of the
mattress support
to accommodate the stretching of the patient. As the mattress placed on the
mattress
support is typically resilient, the mattress can accommodate this lengthening
effect.
Preferably, the thigh rest and leg rest sections are also curved in the
transverse
direction of the mattress support. Advantageously, the seat section, where
provided, is
similarly curved.
The provision of a curved seat section, or thigh rest section where provided,
augments the amount by which the lowermost part of the back rest section moves
away
from the seat or thigh rest section and hence the amount of lengthening of the
mattress
support.
The structure is such that the sections can also move together when pivoted
downwardly, as would occur when the knee break is raised. This is advantageous
in that it
provides a compressing effect on the mattress rather than a stretching effect
which occurs
with prior art systems. A stretching effect causes the mattress no longer to
provide
satisfactory support at the knee brealc whereas compressing the mattress as
with the
discloses structure allows the mattress to maintain its support
characteristics at the knee
break and elsewhere.
Advantageously, the sections of the mattress support are removable, for
washing
and the like.
In the preferred embodiment, the portions of the mattress support are formed
from
blow moulded plastics material. This provides sections which are light but
rigid aiid thus
easily handled by hospital staff when removed from a bed, for example for
cleaning.
According to another aspect of the present invention, there is provided a bed
assembly including a platform as specified herein.
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
3
Embodiments of the present invention are disclosed below, by way of example
only, with reference to the accompanying drawings, in which:
Figure 1 shows a left-side perspective view from above of a preferred
embodiment
of a bed assembly in a flat configuration;
Figure 2 shows a right-side perspective view from above of the bed assembly of
Figure 1 in a chair configuration;
Figure 3 shows the bed assembly of Figures 1 and 2 in the chair configuration
with
the mattress support panels and patient support panels removed;
Figure 4 is a plan view of a part of the bed assembly of Figure 1;
Figures 5A and 5B shows a bed extension mechanism in extended and
non-extended positions;
Figure 6 shows in plan view and in schematic form two mattress support
sections of
the bed of Figure 1;
Figure 7 is a plan view of the bed assembly of Figure 3;
Figure 8 is an enlarged view of a portion of the plan view of Figure 7;
Figure 9 is an enlarged view of a portion of the plan view of Figure 7;
Figure 10 shows a side elevational view of the mattress support panels only of
the
bed assembly of Figure 1, with the bed in a chair configuration;
Figure 11 is an enlarged view of a part of the bed assembly of Figure 1; and
Figure 12 shows a keypad zone of the bed of Figure 1 in use by a patient.
Referring to Figure 1, there is shown a preferred embodiment of bed assembly
10
which includes a wheeled base 12 provided with four castors 14, a headboard 16
and
footboard 18. Coupled to the base 12 is a bed platform 20 which can be raised
and
lowered relative to the base 12 and tilted by means of one or more electrical
actuators (not
shown), also of conventional type.
The platform 20 is provided with a frame 22 formed, in this embodiment, of
four
frame sections 24, 26, 28 and 30 which are coupled to one another by means of
hinged
joints 32, 34 and 36. The fraine 22 is typically made of metal or a metal
alloy.
Each frame section 24-30 is provided with an upper frame member having
substantially vertical inner side walls 38 (better seen in Figures 2 and 3)
and a plurality of
depending transverse struts 40 (better seen in Figures 3 and 4) which form a
recessed
support surface for supporting, in this embodiment, four mattress support
panels 50, 52, 54
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
4
and 56. These panels 50-56, together with the pivoting frame members 24-30,
form
respectively the backrest section, seat section, thigh rest section and leg
rest section
typically found in conformable beds of this nature.
The hinges 32, 34 and 36 are provided in the upper frame members 24-30 and
enable the frame members to pivot relative to one another about the hinges 32-
36, as will
be apparent from a consideration of Figures 2, 3 and 7 to 9, and described in
detail below.
It can be seen that the hinges 32-36 are built into the upper frame meinbers
24-30 and
present substantially smooth outer surfaces in order to prevent any discomfort
or injury to
the patient or care staff.
As can be seen in Figure 1, the mattress support panels 50-56 are curved so as
to
present a concave upper surface when looking down on the bed platform 20. The
panels
50-56 lie below the frame walls 38, preferably by a distance sufficient to
allow a mattress
placed on the panels 50-56 to fit within the frame 22 so as to be held by the
substantially
vertical side surfaces provided by the walls 38 of the frame 22. That distance
is preferably
less than this so that the upper surface of the mattress extends above the
frame 22, to hold
the patient comfortably above the hard surfaces of the frame 22 (as shown in
Figure 11).
At least some of the mattress support panels 50-56 are preferably removable
and
advantageously made of blow mouldings from any suitable plastics material. The
panels
50-56 are rigid.
Cut-outs 60 in the panels 50-56 provide handles for easy removal of the panels
50-56 from the bed 10 and for their handling. There are preferably also
provided snap
fittings 55 (some of which are visible in Figure 10) on the underside surfaces
of the panels
50-56 which snap onto the transverse struts 40 to retain the panels in place.
In the
preferred embodiinent, each snap fitting is formed from one or more bosses
extending
beyond the lower surfaces of the panels 50-56, the bosses having curved
surfaces which
form a snap fit gripper member which snaps on to the struts 40.
Figure 1 also shows two patient retention panels 80, 82. Typically,
corresponding
retention panels are provided on the other side of the bed assembly 10 but are
omitted from
Figure 1 for the purposes of clarity. These panels, which can be of a type
lknown in the art,
can be moved between the raised position shown and a lowered position in
whicli they lie
alongside the frame 22 so as to be below the level of the mattress of the bed.
In the raised
position the panels 80, 82 retain a patient on the bed, while in the lowered
position they
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
enable a patient to get off and get onto the bed and also provide unimpeded
access to the
patient.
Referring now to Figure 2, the bed assembly of Figure 1 is shown in a chair
configuration. In this configuration the back rest 30, 50 is raised by
pivoting of the hinge
5 32 between the back rest section 30 and the seat section 28. In the
configuration shown the
hinge point 36 between the thigh rest 54 and the leg rest 56 is also raised.
This raised
configuration of the hinge 36 represents a knee break such that in the
configuration shown
in Figure 2 a patient would be sitting up with knees raised.
The various sections 24-30 of the frame 22 can be moved in the manner shown by
means of one or more actuators provided in the bed assembly 10. The actuators
are well
known in the art, as is the type of control system used to control them, so
they will not be
described in further detail herein.
The bed sections 24-30 and actuators allow the bed to be reconfigured from the
lying position shown in Figure 1 to a sitting position as shown in Figure 2
and also into
many other configurations, including, for example one in which the knee break
at hinge 36
is raised and the leg rest section 24 also raised upwardly to keep a patient's
legs
substantially horizontal. For this latter configuration, there is provided an
actuator which
is coupled to the leg rest section 24 to effect such moveinent. This actuator
arrangement is
well known in the art so is not described in further detail herein.
Figure 2 also shows a sub-frame 42 which supports the platform 20, typically
by
being attached to the seat section 28 and also to the actuators and to a
control unit. The
sub-frame 42 also supports the struts 44 which raise and lower the sub-fraine
42 and hence
the platform 20 relative to the base 12. This sub-frame is the subject of the
applicant's
co-pending British patent application number 0523174.1 filed the same day as
the present
application and does not need to be described in further detail herein.
Referring now to Figure 3, there is shown a perspective view of the bed
assembly
10 of Figure 2 but which omits for the purposes of clarity the mattress
support panels
50-56, the head board 16, the foot board 18, the patient retention panels 80,
82 and a
number of other components shown in Figure 2.
The transverse struts 40 which depend from the frame 22 are clearly visible in
this
Figure. They are provided in number and in location where support is needed
for the
mattress support panels 50-56 and which allow good access to the bed
components
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
6
underlying the platform 20, as will be more apparent from a consideration of
Figure 4. In
this embodiment, there are provided three transverse struts 40 in the back
rest section 30,
in light of the greater weight supported by this section of the bed, and two
struts 40 in each
of the other sections 24-28. Of course, it is possible to provide just two
struts in the section
30 if these are made sufficiently strong.
The back rest section 30, the thigh rest section 26 and the leg rest section
24 are
also provided with longitudinally extending strengthening struts 41 between
two adjacent
transverse struts 40.
It is preferred that the transverse struts 40 are generally rectangular in
cross-section
as this provides a secure coupling with the snap fasteners provided on the
underside of the
mattress support panels 50-56.
Figure 3 also shows two of the actuators 43 used for moving the frame sections
24-30. As can be seen, these are secured to the sub-frame 42.
Referring now to Figure 4, this shows the bed features of Figure 3 in plan
view
wit11 the frame 20 in a flat configuration. It can be seen that the provision
of readily
removable mattress support panels 50-56 and of support struts 40, 41, rather
than a solid
non-removable flat base, provides good access to the components of the bed 10
underlying
the frame 22. In this case, the actuators 43 are readily visible and
accessible from above
the bed 10 through the frame 22, as well as other coinponents such as the
control unit (not
visible) typically provided in such bed assemblies. This enables servicing of
these
components from above the bed, that is without having to turn the bed onto its
side or
upside down.
Figures 5A and 5B show a detail of the foot section 24 of the frame 22, with
its
mattress support pane156 fitted. The end of the foot section 24 is extendable.
This is
achieved by providing the end strut 110 with first and second parallel rods or
tubes 112,
114 either side thereof. These rods have a transverse shape which corresponds
to the
internal shape of the struts 116, 118 forming the foot rest section 24, so as
to be slidable
therein as shown in Figures 5A and 5B. As will be apparent from Figure 5A,
when the
foot rest section 24 is in its extended condition, the rods 112, 114 continue
the side wall of
the frame 22, thereby retaining the side support surfaces complete around the
whole of the
frame 22.
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
7
First and second latches or locks 120 are provided for locking each rod 112 in
either the retracted or in the extended positions. The latches 120 could
simply be sprung
pins fitting into appropriate apertures or bores in the rods 112, 114 or could
be screw locks
which tighten against the rods 112. The type of latch or lock is not
important.
Referring now to Figure 6, there is shown in plan view iul schematic form the
arrangement of the mattress support panels 50, 52 of the bed of Figures 1 and
2. The
support panel 50, which forms the baclc rest section of the bed 10, includes a
first end wall
62 and an opposing end wa1164. The mattress support panel 52, which forms the
seat
portion of the bed 10, includes a first end wall 66 and a second end wall 68.
The walls 62
and 66 are adjacent one another, as shown in Figure 6.
When the bed is in a flat position, depicted by the solid lines in Figure 3
and as
shown in Figure 1, the spacing between the two panels 50, 52 is shown as
distance d,
which can be any suitable distance which will not adversely affect the support
of a patient
on a mattress laid over the panels 50-56. The distance d will typically be a
few
centimetres, often around 10 cm or so.
On the other hand, when the support panel 50 is pivoted to a raised patient
sitting
position as shown in Figure 2, the distance between the end walls 62, 66 of
the panels 50,
52 respectively increases to the distance D shown in Figure 6. It can be seen
that distance
D is considerably larger than the distance d when the two panels are lying
flat.
There are two primary factors which cause the increase in the distance between
the
two end walls 62, 66. The first is the curvature of the panels 50, 52 and the
fact that the
pivoting point is at the sides of the panel. The centre of the panels 50, 52
are substantially
below the sides, thereby causing this increase in distance during the pivoting
motion. The
second factor is that the pivot 32 is raised above even the highest points of
the panels 50,
52 (that is above their raised sides) which causes additional movement away
from the
panel 52 including at the ends 70.
This increase in spacing is advantageous because when a person moves from a
lying position to a sitting position the person stretches at the point of
bending (that is
between the patient's back and lower thighs). Thus, this arrangement follows
the
extension of the person and therefore makes it much more comfortable to a
patient. Prior
art beds, which have the pivot points substantially at the level of the
mattress support
sections and which have mattress support sections which are substantially
flat, do not
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
8
benefit froin this increase in spacing between the sections and therefore from
any increase
in the effective length of the mattress support base. They can provide a
pinching effect on
the patient.
The reader will appreciate that the two factors mentioned above could be
provided
independently of one another, although with reduced lengthening effect.
Figure 7 shows a plan view of the bed of Figure 1 in the chair configuration,
while
Figure 8 shows an enlarged view of the head end of the bed of Figure 7. A
comparison of
Figure 1 with Figures 7 and 8 shows the increase in spacing between the edges
62, 66 of
the panels 50, 52 from the lying to the seating positions.
There is an other advantageous feature of this structure of the platform 20,
this
being at the thigh section 54. As can be seen in Figure 1, the spacing, D',
between the
thigh rest panel 54 and the leg rest panel 56 is relatively large when the
platform 20 is in
the flat configuration. However, when the hinge 36 is raised to form the knee
break, this
spacing is reduced substantially, to d' as shown in Figure 9. This reduction
in spacing
causes the lower surface of the mattress to coinpress longitudinally as a
result of a
shortening in the overall length of the portions 54, 56 of the mattress
support. This enables
the mattress to maintain contact with the rear of a patient's knee. It has
been found that if
there is no such compression of the mattress longitudinally, as would be the
case if the
spacing between the thigh and leg rest sections 54, 56 were to remain the
same, the
mattress becomes stretched over the lcnee break and can lose contact with the
rear of a
patient's lulees, thereby losing the supporting effect it should provide.
Figure 10 shows the mattress support panels 50-56 in the chair configuration
of the
bed. The spacings between the panels in this configuration can be clearly
seen. There is,
however, another feature evident in Figure 10, related to the movement of the
thigh rest
section 54. As can be seen in Figure 10, with the thigh rest section pivoted
upwardly as
shown, the rear edge 111 of the thigh rest 54 is higher than the front edge
113 of the seat
section. This is caused by the fact that the rear edge 111 is longitudinally
spaced from the
hinge 34, along the length of the bed. As a result of this, pivoting of the
frame section 28
about the hinge 34 will cause the panel 54 not only to pivot but also to rise
relative to its
rest position. This rising of the thigh rest pane154 provides better support
to the underside
of a patient's thigh than do existing configurable bed assemblies.
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
9
Referring now to Figure 11, the bed 10 is shown in the lying configuration, in
order
better to see the patient retention panels 80, 82 for retaining the patient on
the bed. The
panels 80, 82 are typically made from a plastics material or from metal
covered with a
plastics cladding.
The patient retention pane180 is coupled to the frame member 30 forming the
back
rest section of the bed 10 and is able to move therewitli, as will be apparent
in particular
fiom Figure 2. The patient retention pane182 is coupled to the seat section 28
of the frame
22 and in practice does not move as the seat section 28, in this embodiment,
is the one
stationary member of the frame 22 (although it does, of course, move with the
frame 22 as
this is raised, lowered and tilted).
As is best appreciated from Figure 2, when the back rest section 30, 50 is
pivoted
upwardly towards a patient sitting position, the patient retention pane180
will move over
the retention pane182. For this purpose, the pane180 includes a concave facing
surface 92
which faces a convex surface 94 of the retention pane182. As the pane180 moves
upwardly and around the pane182, the surface 92 slides over the surface 94
retaining
substantially the same gap g between the two surfaces 92 and 94. As a result
of this, the
combination of the two panels 80, 82 provides a substantially continuous
support surface
throughout the movement of the retention pane180, without creating between the
two
panels any constriction which could trap part of a patient's body or that of
hospital staff.
As shown in particular in Figures 11 and 12, there can be seen in schematic
form an
example of a preferred embodiment of unit 100 for supporting a keypad (not
shown) which
allows the patient to operate the various functions of the bed 10.
In this embodiment, the keypad unit 100 is provided with a protruding ineinber
102
which extends beyond the general outer perimeter of the patient support
pane180 and in a
direction towards the foot end of the bed 10. The unit 100 is fitted to the
patient retention
pane180 so as to move with that panel upon movement of the back rest section
30, 50, in
such a manner that it maintains its position relative to the backrest section
30, 50 and hence
relative to a patient lying on the bed 10. The unit 100 is located so as to be
easily
accessible by a patient on the bed by means of the patient's hand at that side
of the bed, as
shown in particular in Figure 6. The position of the unit 100 could be
described as being
approximately at the shoulder area of a patient lying or sitting on the bed
10.
CA 02615954 2008-01-18
WO 2007/010218 PCT/GB2006/002633
As can also be seen in Figure 12, the shape and structure of the unit 10 is
such that
a patient is able to place his/her fingers on the outer side of the unit 100
and then to operate
a keypad (not shown) on the inner/patient side of the unit 100. The patient is
therefore able
to apply an opposing pressure at the rear side of the unit 100 to the pressure
applied when
5 pressing the buttons of the key pad, which in practice stabilises the unit
100. This feature
contrasts with the existing keypads provided on the patient support panels,
which tend to
be difficult to operate because the panels generally have some flexibility to
them.
The keypad which would be provided in the unit 100 is of a type equivalent to
the
keypads already used in such beds and therefore is not described in any
further detail
10 herein.
Referring in particular to Figure 11, it is preferred that the unit 100 is
fitted to the
patient support pane180 by first and second flanges 104, 106 which can be
secured to the
panel 80 either by suitable snap fit connections and/or by one or more screws.
Within the
unit 100 there is provided a plug or socket which fits to a complimentary
socket/plug to
make the necessary electrical connections between the keypad of the unit 100
and the
control system of the bed 10.
The preferred structure of the keypad unit 100 facilitates the assembly of the
unit
100 to the bed 10 and also enables its easy replacement in case the keypad is
in some way
damaged during use or shipping.
