BACKGROUND OF THE INVENTION
The invention is particularly related to a mattress which is suitable for use in medical applications for the improved comfort of patients who are confined to bed for long periods of brne. Such patients often suffer from bedsores due to the concentration of pressure in regions where the patient's body touches the mattress, particularly in the regions of the shoulders, hips and heels. Another problem arising in medical environments is the possibility of infection of the mattress with bacteria which could subsequently infect a patient.
The present invention is directed towards overcoming these problems.
SUMMARY OF THE INVENTION
According to the invention there is provided a mattress, comprising an outer casing within which is mounted a resilient support, wherein the support is sealed within the casing and said casing has an air vent in a side wall of the casing. Thus, conveniently the casing can be formed with welded seams without ballooning of the casing. Further, the vent allows the mattress to breathe.
In a particularly preferred embodiment at least an upper portion of the resilient support is formed by a visco-elastic foam. Advantageously the visco-elastic slow foam or memory foam has a tendency to mould itself into the shape of the body lying on the foam layer, thus providing an even distribution of pressure over the body of the patient and thus minimising localised high pressure points.
In a preferred embodiment, a filter is mounted across the air vent to prevent the ingress of bacteria to an interior of the casing.
In another embodiment the filter has pores for through-passage of air, said pores being sized to trap any particle greater than 1 micron in size. As bacteria typically attaches to particles over 6 microns in size and the filter blocks the passage of any particle greater than 1 micron in size, the filter effectively prevents ingress of bacteria into the cover.
In a further embodiment a flap is mounted on the cover, the flap being fixed to an exterior of the cover above the vent and extending downwardly over the vent. This advantageously protects the vent and filter being damaged by fluid such as when cleaning the mattress for example.
The cover is preferably of an elastic material which is stretched over the foam core. Additional anti-bacterial, fungistatic protection may be provided for the foam core and for the cover if desired.
In a preferred embodiment of the invention at least portion of the foam layer has a profiled area comprising projections and hollows at an upper support surface of the foam layer.
In a particularly preferred embodiment said profiled area is at a lower end of the foam layer forming a heel support region of the foam layer. This advantageously provides extra pressure reduction in the heel area of a patient when the mattress is in use.
In another embodiment the projections are of generally flat-topped pyramid shape arranged in a chequered formation with hollows formed therebetween.
In another embodiment the visco-elastic foam has a density in the range 60-95 kg/m3. Most preferably the density of the visco-elastic foam is 85 kg/m3.
In a particularly preferred embodiment, the support is provided by a multi-layered support core comprising the visco-elastic foam top layer mounted on at least one bottom layer of foam having a greater resilience than the visco-elastic foam. This provides added rigidity and support to the core.
In a particularly preferred embodiment, the bottom layer comprises a combustion modified high resilient foam.
Preferably the casing is of a stretchable elastic material.
In another embodiment the resilient support further includes an outer frame mounted about a side of said layers forming an endless side margin about said layers, said outer frame being formed of a high index foam.
In a particularly preferred embodiment the mattress includes a composite resilient support having a laminated core with a rectangular bottom layer and an associated rectangular top layer superimposed on said bottom layer, a top face of the bottom layer engaging and adhesively secured to a complementary bottom face of the top layer, said bottom layer being formed of a combustion modified high resilience foam and said top layer being formed of a visco-elastic foam, said layers being of equal depth, said core being encircled by an outer frame formed of a high index foam which extends about the side faces and end faces of the core and being adhesively secured thereto, a sealed casing mounted about said core, said casing being formed of an elastic material stretched about the core with overlapping seams of the core being welded together to form a sealed enclosure about the core, an opening in said casing forming a vent to allow air passage between an interior and an exterior of the casing, a filter mounted across the vent and a flap mounted on the casing covering the vent and being fixed to said casing about a periphery of the flap above and at each side of the vent leaving a downwardly facing opening between a lower end of the flap and the casing for air passage to and from the air vent.
In another aspect the invention provides a mattress comprising an outer casing within which is mounted a resilient support, at least an upper portion of the support being formed by a layer of visco-elastic foam, the support having lower end forming a heel support region of the support, an upper surface of said heel support region being a profiled area of projections and hollows. Preferably the projections have a flat-topped pyramid shape.
In another embodiment the support is sealed within the casing and said casing has an air vent in a side wall of the casing. Ideally a filter is mounted across the air vent to prevent ingress of bacteria to an interior of the casing. Preferably a flap is mounted onto the casing, the flap being fixed to an exterior of the casing above the vent and extending downwardly over the vent, a free edge of the flap defining with the casing an opening for through passage of air to and from the vent.
In a further aspect the invention provides a mattress comprising an elastic outer casing 5 within which is mounted a resilient support, at least an upper portion of the support being formed by a layer of visco-elastic foam having a density of about 85 kg/m3.
In another embodiment the resilient support has a laminated construction including a rectangular bottom layer and an associated rectangular top layer superimposed on said bottom layer, a top face of the bottom layer engaging and being adhesively secured to a complementary bottom face of the top layer, said bottom layer being formed of a combustion modified high resilience foam and said top layer being formed by the layer of visco-elastic foam.