U.S. patent application number 09/771264 was filed with the patent office on 2001-11-01 for mattress.
Invention is credited to Daly, Noel.
Application Number | 20010034908 09/771264 |
Document ID | / |
Family ID | 9890707 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010034908 |
Kind Code |
A1 |
Daly, Noel |
November 1, 2001 |
Mattress
Abstract
An alternating pressure mattress is provided with an upper
visco-elastic foam layer to reduce the pressure variation flet by a
patient lying on the mattress. The foam layer may extend into gaps
between the cells making up the mattress. A foam layer may also be
provided beneath the cells so that the mattress has a more
conventional appearance.
Inventors: |
Daly, Noel; (Middleton,
IE) |
Correspondence
Address: |
HICKMAN COLEMAN & HUGHES, LLP
P.O. BOX 52037
Palo Alto
CA
94306
US
|
Family ID: |
9890707 |
Appl. No.: |
09/771264 |
Filed: |
January 26, 2001 |
Current U.S.
Class: |
5/713 |
Current CPC
Class: |
A61G 7/05776 20130101;
A61G 2203/44 20130101 |
Class at
Publication: |
5/713 |
International
Class: |
A47C 027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 29, 2000 |
GB |
0010401.8 |
Claims
1. A mattress for assisting in the treatment of ulcers comprising:
a plurality of inflatable bladders defining a support surface for
supporting a patient; a control system for supplying pressurised
air to the bladders for selective inflation and deflation of the
bladders; and a visco elastic foam layer covering at least a
portion of the support surface.
2. A mattress as claimed in claim 1, wherein the foam is pressure
and/or temperature sensitive.
3. A mattress as claimed in claim 1 wherein the inflatable bladders
are separated by visco elastic foam walls.
4. A mattress as claimed in claim 1, wherein the foam is
breathable.
5. A mattress as claimed in claim 1 wherein the inflatable bladders
are positioned within the visco elastic foam mattress.
6. A mattress as claimed in claim 1 wherein the mattress is coated
in a polyurethane cover, preferably a thermoplastic cover.
7. A mattress as claimed in claim 6, wherein the cover is adapted
to be impermeable to fluids but permeable to vapours.
8. A mattress as claimed in claim 1 wherein the control system
comprises at least one rapid deflation valve for deflating the
bladders.
9. A mattress as claimed in claim 1 further comprising a pressure
sensor for monitoring the pressure in at least one inflatable
bladder.
10. A mattress as claimed in claim 1 wherein the control system can
be programmed to inflate and deflate the bladders in a plurality of
different cycles.
11. A mattress for assisting in the treatment of ulcers comprising:
a plurality of inflatable bladders defining a support surface for
supporting a patient; a control system for supplying pressured air
to the bladders for selective inflation and deflation of the
bladders; and a visco elastic foam shell adapted to absorb pressure
so reducing the pressure between patient and mattress.
Description
[0001] The present invention relates to a mattress for retarding
the development of ulcers. More particularly, but not exclusively,
the present invention relates to a mattress comprising a plurality
of inflatable bladders covered by a visco elastic foam layer.
[0002] The development of pressure ulcers by bed bound patients is
a well known problem. In hospitals the nursing staff tend to turn
patients typically every two or three hours to inhibit the
development of such ulcers. This is time consuming and can
occasionally result in injury to the nursing staff.
[0003] Dynamic air flotation mattresses are well known in the field
of ulcer reduction. Such mattresses comprise a series of transverse
air filled tubes which provide a flotation base beneath the
patient. A control unit inflates and deflates these tubes to ensure
that the pressure points beneath the patient alter continuously.
Since no one point under the patient is continuously exposed to
pressure from the mattress ulcer formation is inhibited. Such
mattresses are used for patients at high risk of decubitus ulcer
development or tissue damage.
[0004] However, such flotation mattresses can create a feeling of
obvious motion. Coherent patients with good sensations can feel
this motion and instantly and immediately dislike the feeling.
[0005] Accordingly, a first aspect of the present invention
provides a mattress for assisting in the treatment of ulcers
comprising:
[0006] a plurality of inflatable bladders defining a support
surface for supporting a patient;
[0007] a control system for supplying pressurised air to the
bladders for selective inflation and deflation of the bladders;
and
[0008] a visco elastic foam layer covering at least a portion of
the support surface.
[0009] The visco elastic layer reduces the motion feeling
increasing patient comfort and reducing peak pressures generated by
the bladders. The visco elastic layer therefore acts like a damper
or shock absorber and absorbs the energy output from the inflated
core. Also, the visco elastic layer allows greater patient
conformity i.e. allows the distribution of patient load over a
wider surface area.
[0010] In addition, the inflatable bladder of known flotation
mattresses are made from materials having very little stretch. Such
material result in localised contact areas between the patient and
the mattress resulting in a localised pressure being applied to the
skin of the patient. Whilst the points of contact between the
mattress and the patient vary as the bladders inflate and deflate
this can still result in decubitus ulcer formation. The visco
elastic foam layer of the mattress according to the invention
disperses the pressure between patient and mattress over a wide
area, inhibiting peak pressure build up.
[0011] Also, the mattress according to the invention is suitable
for use by low risk to critical care patients. By maintaining the
inflation bladders at a constant pressure the mattress functions as
a standard visco elastic foam mattress suitable for use by low risk
patients. By varying the pressure in the inflation bladders the
mattress becomes suitable for use by critical care patients i.e. it
acts as an alternating pressure therapy unit.
[0012] Preferably, the inflatable bladders, are separated by visco
elastic foam walls. Such walls absorb the horizontal forces being
exerted on the sides of the inflatable bladder walls when the
patient is on the mattress. This results in a more gradual
reduction in pressure on the patient as the pressure in the
inflatable bladders is varied, increasing patient comfort.
[0013] The foam can be temperature and/or pressure sensitive. This
allows the foam to mould itself around the patient and thereby
increases patient comfort and pressure reduction.
[0014] The foam can be breathable and preferably open celled. This
reduces moisture build-up within the foam and ensures a cool and
airy microclimate under the patient.
[0015] The inflatable bladders can be positioned within the visco
elastic foam mattress. The mattress has the appearance of a
standard mattress rather than a floatation device. This has a
significant patient perception advantage.
[0016] The mattress can be coated in a poly-urethane cover,
preferably a thermoplastic cover. This prevents entry of fluids and
bacteria into the foam layer. This enables cleaning or washing down
to be performed by infection control/hospital cleaning staff,
rather than being taken off site.
[0017] Preferably the cover is impermeable to fluids but permeable
to vapours. This maintains breathability between the patient and
the mattress preventing a moist microclimate developing beneath the
patient which would lead to skin tissue breakdown.
[0018] Preferably the control system comprises a rapid deflation
valve for deflating the bladders. This enables the mattress to be
rapidly deflated, for example, it is required to apply CPR to the
patient.
[0019] The mattress can further comprise a pressure sensor for
monitoring the pressure in at least one inflatable bladder. This
enables the control system to maintain the correct pressure within
the bladders. Preferably, the pressure sensor generates an alarm
signal if the pressure in the bladder drops.
[0020] Preferably the control system can be programmed to inflate
and deflate the bladders on a plurality of different cycles.
[0021] In a further aspect of the invention there is provided a
mattress for assisting in the treatment of ulcers comprising:
[0022] a plurality of inflatable bladders defining a support
surface for supporting a patient;
[0023] a control system for supplying pressured air to the bladders
for selective inflation and deflation of the bladders; and
[0024] a visco elastic foam shell adapted to absorb pressure so
reducing the pressure between patient and mattress.
[0025] The present invention will now be described by way of
example only, and not in any limitative sense, with reference to
the accompanying drawing in which:
[0026] FIG. 1 shows in cross section, a first embodiment of a
mattress according to the invention;
[0027] FIG. 2 shows, in cross section, a second embodiment of a
mattress according to the invention.
[0028] FIG. 3 shows, in perspective view the second embodiment of
the invention with the air bladders removed.
[0029] FIG. 4 shows, in cross section, a rotational therapy base
which may optionally be used with a mattress according to the
invention.
[0030] The mattress shown in FIG. 1 comprises a series of
inflatable bladders (1) each in the form of a tube. The tubes, in
combination, define a support surface for supporting a patient.
[0031] The inflatable bladders (1) are manufactured from high
stretch hydrophobic polyurethane material. The stretch in the
material ensures full patient conformity and reduces shear forces
on the skin tissue. These shear forces are a key contribution to
skin breakdown.
[0032] In an alternative embodiment the inflatable bladders (1) are
manufactured from a nylon material with a thermoplastic
polyurethane coating. Such a coating has microscopic holes which
allow some air loss from the bladders during use thereby reducing
mattress temperature and assisting the healing of open wounds.
[0033] Typically the bladders are approximately 90 cm in length and
14 cm in diameter. This depends upon mattress size and
clinical/patient requirements.
[0034] The inflatable bladders (1) are connected via air lines (2)
to a control system (3). The control system (3) selectively
supplies pressurised air to the bladders (1) to control their
inflation and deflation.
[0035] In use the control system inflates and deflates each tube
(1) independently. Typically AB or ABC alternating cycles are used.
In an AB alternating cycle each tube (1) is inflated and deflated
out of phase with its neighbour. In an ABC cycle tubes A and B
inflate whilst C deflates, then B and C inflate whilst A deflates
and so on. Cycle time is typically of the order 6 minutes for high
risk patients, 10 to 15 minutes for medium risk patients and 15 to
21 minutes for low risk patients. Such cycles ensure that the
points of contact between the patient and mattress vary slowly over
time.
[0036] The maximum and minimum air pressures in the air bladders
(1) during each cycle can be varied by programming the control
system (3). This is to allow for patients of different weights.
[0037] Each bladder can be easily and immediately removed and
exchanged if damaged or punctured. The pressure feedback sensor
system (4) in the pump unit sounds an alarm and activates a visual
alarm if a pressure drop due to tube damage is detected by the
sensor.
[0038] The pressure control system can be programmed with different
cycles depending on the patient weight. If the feedback pressure
sensor system detects from pressure measurement that the incorrect
patient weight has been entered the visual alarm will be activated.
If this is not corrected then the audible alarm will be
activated.
[0039] The bladder system comprises two rapid deflation valves for
rapid deflation of the mattress tubing. When opened these allow
deflation of the mattress within approximately ten seconds.
[0040] In this embodiment the bladders (1), are embedded within a
visco elastic foam shell (7). The foam shell is pressure sensitive.
The foam typically has an uncompressed density of between 58 kg and
62 kg, a hardness of 80-120 N at 20.degree. C., and is fire
retardant. The foam is open celled and breathable.
[0041] The foam (7) extends in walls (8) between the air bladders
(1). For this type of foam the walls (8) are optimally between 10
and 20 mms thick. Such walls (8) slowly absorb the forces exerted
by the inflatable bladders (1) thereby reducing peak pressures of
the patient mattress/patient interface. This results in a more
gradual reduction in pressure beneath the patient enhancing patient
comfort and reducing the alternating flotation feel of the bladder
system. If this layer is less than 10 mm thick the layer will
compress too easily and the comfort aspect will be lost. If the
layer is thicker than 20 mm then the benefit of the inflatable
bladders (1) is lost.
[0042] The foam (7) is sealed within a plastic polyurethane
multi-stretch cover (9). The cover (9) is made from coated
polyurethane coating (10) on a polyester weave (11). The cover (9)
is constructed from a plurality of layers to ensure impermeability
to fluids but rapid vapour permeability. This allows moisture
within the foam (7) to escape through the cover (9).
[0043] The coating (l0) and base weave (11) are designed to have,
as close as possible, equal stretch coefficients. This reduces the
shear forces between the coating (10) and the base weave (11) which
prevents the separation of these layers.
[0044] The coating layer (10) can be washed down by hospital
cleaning staff or laundered or autoclaved on site. There is no need
for the mattress to be decontaminated by a specialist technique.
This considerably reduces maintenance costs.
[0045] The base weave layer (11) typically has a weight of between
125 and 150 g/m.sup.2. The coating (10) typically has a weight of
approximately 100 g/m.sup.2.
[0046] Shown in FIG. 2 is a further embodiment of a mattress
according to the invention, shown in cross section. In this
embodiment the foam layer (7) comprises two parts. The first part
comprises a plurality of recess into which the open bladders are
inserted. The second part of the foam layer is in the form of a
sheet which is attached to the first part as shown to cover the
recesses.
[0047] This mattress comprises a plurality (typically 13) of
inflatable bladders and also at least one static tube in the head
section of the mattress. The static tube is designed to keep the
head section under the pillow stable. Inflation/deflation of this
area is uncomfortable for the patient.
[0048] FIG. 3 shows the mattress of FIG. 2 with the air bladders
removed.
[0049] Shown in FIG. 4, in cross section is a rotational therapy
base which may optionally be used to rotate the bed from one side
to another. The rotational therapy base comprises a plurality of
bladders which can, when selectively inflated or deflated pivot the
mattress about its long axis as shown.
* * * * *