WO1991017684A1

WO1991017684A1 - Cushion made from plastic foam

Info

Publication number: WO1991017684A1
Application number: PCT/DK1991/000136
Authority: WO
Inventors: Joern Moeller Madsen
Original assignee: Bay Jacobsen Af 1991 A/S
Priority date: 1990-05-23
Filing date: 1991-05-21
Publication date: 1991-11-28
Also published as: DK128390A; DK128390D0; AU7904191A

Abstract

The cushion consists of a wedge-shaped bottom portion (2) of plastic foam, which changes impression hardness and carrying capacity at fluctuating temperature and air humidity, and of a wedge-shaped top portion (1) of a soft, more porous plastic foam, which from the backwardly inclined front surface (3) shows decreased thickness towards the rear edge of the cushion. A large number of through-going holes extending from the top surface of the cushion unto its under surface are functioning as ventilating channels which impede the formation of a moist environment and of local heating. The cushion is suitable for impeding the development of pressure sores and is in particular intended for cushions used in wheelchairs.

Description

CUSHION MADE FROM PLASTIC FOAM

The invention relates to a laminated cushion made from plastic foam, especially a cushion having a cover and intended to be used as anti-decubitus cushion for the prevention of pressure sores on persons using wheel chairs or others who are forced to remain seated for long periods.

With a view to avoiding development of bedsores it is im- portant to ensure the possibly best spreading of pressure of the patient's weight over the pad, and for that purpose cushions have been developped containing jelly, water or air whereby excellent spreading of pressure is achieved. However, a cushion which will efficiently prevent pressure bedsores and which will at the same time encourage choosing the appropriate sitting posture should meet several other conditions. In particular it is important that it will carry off heat and moisture which - as it is well-known contribute very much to the development of pressure sores.

It is the object of the invention to provide a cushion of that kind, which is less expensive and easier to produce and handle than known cushions having efficient pressure spreading by means of water, jelly or air, but which is at the same time providing equally good spreading of pressure and improved carrying off of water and moisture and encou¬ raging the choosing of a comfortable sitting posture taking principles of ergonomics into consideration.

According to the invention this is achieved by a cushion consisting of two mainly wedge-shaped portions assembled along a plane extending backwardly oblique and upwardly from the backwardly inclined front plate of the cushion, the bottom portion consisting of a visco-elastic, temper- ature sensitive, comparatively rigid plastic foam changing the impression hardness and carrying capacity at fluct- uating temperature and air humidity, and the top portion consisting of a soft, more porous plastic foam, e.g. soft polyurethane foam, and in that in both portions of the cushion a ventilating system is provided in the form of through-going channels.

A cushion of that kind is easily produced from two wedge- shaped foam plast elements which are adhered together and in which vertical ^'holes are punched so as to connect the top and bottom sides of the cushion, and the temperature sensitive plastic foam in the bottom part of the cushion is acting in a similar way like contents of jelly, but is more advantageous due to the minimized weight and the eliminated risk of leaks. The fine spreading of pressure is mainly achieved due to the decreased impression hardness and the resulting carrying capacity at increasing temperature in areas immediately under the patient's protruding spots^' of the behind, which are in particular exposed to pressure sores. The comparatively low carrying capacity of the mat- erial is counterbalanced by the increased thickness of the material at the rear part of the cushion, where the load is highest. By the wedge-shaped upper part having an oblique front surface, produced from ordinary, soft plastic foam it is achieved that users of the seat will without overloading the underside of the thighs or impeding the circulation, and even when the body is slightly bent forward can be brought into an appropriate sitting posture in accordance with ergonometric principles, whereby the loin can keep its natural swaying, which effect is often aimed at by letting the seat be tilting a bit downwards towards the front edge. For elderly people in particular it may be a problem to endure the load on loins and hips caused by an "ordinary" cushions. If the problem is osteoporosis and degenerative arthritis it is extremely important to avoid unnecessary loading of loin and hips. When applying an ordinary pad, a pressure on the sciatic nerve may.occur if some kind of bolster is not applied.

By letting according to the invention the plane assembly surface of the cushion extend on to the mainly vertical rear surface of the cushion it is achieved that the thin¬ nest, most rear part of the top part of the cushion contr¬ ibute to avoiding malaise due to the more rigid, pressure carrying and distributing corresponding part of the bottom portion of the cushion.

The invention will now be explained with reference to an embodiment of the cushion and referring to the drawing in which

Fig. 1 shows a diagonal top view of the cushion,

fig. 2 shows a vertical section through the cushion, and

fig. 3 shows a diagonal bottom view of the cushion.

The cushion shown in the drawing is intended to be provided with an ordinary, removable cover and has an upper wedge- shaped portion 1 the thickness of which is from an oblique- ly backwardly inclined front surface 3 declining towards the rear edge 4 of the cushion. The upper portion 1 of the cushion is by adhesion or otherwise connected to a bottom, wedge-shaped portion 2 which consists of a compar¬ atively rigid, temperature sensitive plastic foam which is characteristic in its impression hardness and thus carrying capacity decreasing at increasing temperature. As the thickness of the portion 2 is increasing from the front edge towards its rear edge 4, it is despite the decrease in carrying capacity at temperature fluctuations capable of enduring both the highest loads occuring under the user's behind, and the lower load of the user's thighs. A suitable plastic foam for achieving efficient pressure spreading is the so-called TEMPUR which is a temperature sensitive poly-

3 urethane foam of high specific weight (70-100 kg/m ) and comparatively low carrying capacity in the temperature range 25-35°C.

The function of the . bottom portion 2 is a pressure spreading one in that the parties of the patient, which are to the highest extent exposed to pressure sores, i.e. extending pressure parties, are due to the body temperature heated whereby the impression hardness of the part of the cushion portion 2 lying immediately thereunder is decr¬ eased, said cushion portion is by its wedge-shaping int¬ ended for receiving loads both under the most intensely strained portions at the rear of the cushion and at the front end of the cushion, which is exposed to lighter loads from the thighs. The top cushion portion 1 makes the patient feels no inconvenience due to the less elastic material in the bottom portion 2 of the cushion, and the wedge-shaping and the oblique front surface 3 further cont¬ ribute to letting the sitting posture of the patient become correct from an ergonometric point of view, also by the body being slightly forwardly inclined.

Beyond the good spreading of pressure over the pad obtained with the cushion, it meets other important conditions with a view to hindering the development of pressure sores, viz. elimination of moist environments and of excessive effect of heat that may occur on a patient sitting on a tight surface. This is achieved by providing through-going holes 5 in the cushion, which extend from the top side of cushion unto its bottom side functioning as ventilating channels securing good air circulation. It is understood that such simple kind of ventilation could be replaced by other chan- nel systems, too, which would, however, usually be more complicated and more expensive to manufacture.

Claims

P A T E N T C L A I M S

1. Laminated cushion of plastic foam, c h a r a c t e r i¬ z e d i n said cushion consisting of two mainly wedge- shaped portions (1,2) assembled along a plane extending backwardly oblique and upwardly from the backwardly incl¬ ined front surface (3) of the cushion, the bottom portion (2) consisting of a visco-elastic, temperature sensitive, comparatively rigid, plastic foam changing the impression hardness and carrying . capacity at fluctuating temperature and air humidity, and the top portion (1) consisting of a soft, more porous plastic foam, and in that in both port¬ ions (1, 2) of the cushion a ventilating system is provided in the form of through-going channels (5).

2. Cushion according to claim 1, c h a r a c t e r¬ i z e i n the channels being mainly vertical holes

(5) connecting the top and under surfaces of the cushion.

3. Cushion according to clailm 1, c h a r a c t e r¬ i z e d i n the plane assembly surface of the cushion extending unto the mainly vertical rear surface (4) of the cushion.

4. Cushion according to any one of the preceding claims, c h a r a c t e r i z e d i n the wedge-shaped bottom portion of the cushion consisting of temperature sensitive

3 polyurethane foam of high specific weight (100-120 kg/m ) and comparatively low carrying capacity in the temperature range 25-35°C.