GB2238716A - Cushion for medical use - Google Patents

Abstract

In a substantially U-shaped cushion (1) for medical purposes, said U-shape defines a central channel (4) wherein the average width of the channel is significantly less than the diameter of a generally circular cut-out area (3) in which the channel terminates, thereby to define opposed projection portions (8) at the conjunction of the channel and the cut-out area. The cushion may be pneumatic or fluid filled but is preferably formed of a laminate of an upper softer and a lower harder layer of closed cell foam. The cushion may be overlaid by a towelling cover. This arrangement allows long stay patients to sit comfortably without obturation of the blood or lymphatic systems. <IMAGE>

Description

CUSHION FOR MEDICAL USE The present invention relates to a cushion for medical use, and particularly to a cushion to support the sitting body so as to reduce the incidence of bedsores as far as possible.

These cushions are becoming steadily more important as the number of old people increases and their life expectancy extends.

It has been conventional to provide a ring shaped cushion filled with air or foam to support the buttocks but these, while better than nothing at all, are not particularly satisfactory since they can cause high pressure under the thighs which impedes lymphatic drainage, impedes venous return, and is generally inefficient at pressure dispersal.

Nelham in Physiotherapy; 1984 and Lowthian in Nursing Times 1985, have shown that the greater trochanter and the posterior thigh areas can tolerate pressures of up to 60 and 80 mm/Hg respectively, whereas the ischium area can only tolerate 40 rmn/Hg over a significant period. The ring shaped cushions exert pressures of about 100 mm/Hg on the posterior thighs when a person is in the sitting position, and it is for this reason that the venous and lymphatic systems are obturated.

The pressure signature of a body on a normal cushion gives value of about 80 mm/Hg under the ischial tuberosities.

Commode cushions are also available, for example those described in US-A3611455. These provide a fluid-filled cut-out design adapted as far as possible to spread the load. However. with commode cushions the load is designed to be taken substantially vertically, whereas in comfortable sitting there is often a forward component in the direction of the legs, as a patient leans back.

With a ring-shaped cut out, this leaning back action tends to increase the pressure on the posterior thighs tending to obturate still further the venous and lymphatic systems. With commode cushions the tendency to slide forward not only increases the pressure on the posterior thighs, but also moves the ischium forward so that it is not fully supported by. the cushion thereby to decrease blood flow in that area.

In order to alleviate these problems the present invention provides a substantially U-shaped cushion for medical purposes, said U-shaped defining a central channel; characterised in that the average width of the channel is significantly less than the diameter of a generally annular cut-out area in which the channel terminates; thereby to define opposed projection portions at the conjunction of the channel and the cut-out area.

By use of these projection portions, a maximum body load can be taken by the posterior thigh area: thereby alleviating the ischium area: particularly when a forward component is applied thereto.

The cushion in accord with the present invention may be pneumatic or fluid filled, but it is preferably formed of a closed cell foam. In a particularly advantageous arrangement the cushion is formed of a laminate of an upper (softer) and a lower (harder) layer of closed cell foam.

The cushion preferably includes a web conjoining the remote ends of the Ushaped cushion so that these cannot splay significantly outwardly. Obviously, such a web can be replaced by suitable reinforcing of the U-shape, but this is not usually economically viable. In a particularly preferred form of the invention the web is formed by an overall cover such as of toweling or a fleece material and formed to be slightly loose over the body of the cushion in order to allow for a measure of relative movement between the cover and the cushion within. This allows the cushion to spread slightly in response to heavy loads.

It will be appreciated that the cushion cover acts not only to protect the cushion, but also to retard foam fatigue by spreading point loads.

The projection portions are important features of the invention because they increase the proportion of the load taken on posterior thigh portions. These projections can be made more effective still by shaping them, as by reducing the thickness on the underside of the foam forming the projections; particularly beneath the portion of the projections within the cut out portion of the cushion. This tends to reduce further the point loading of the cushion against the posterior thigh portions.

The invention will now be described by way of illustration only, with reference to the accompanying drawings wherein Figure 1 shows a plan view from above of a cushion according to the present invention.without its covering web, but with skeletal parts superimposed thereupon.

Figure 2 shows a side elevation from above of a cushion in accordance to the present invention.

The cushion body (1) in accordance to the present invention is formed of a generally U-shaped configuration such that the body (1) is provided with cushion leg elements (2) downwardly depending therefrom. A central portion (3) is provided within the body (1) and operatively associated with a channel portion (4) disposed between the cushion leg elements (2). The shape defined by the cut out portion (3) and the channel (4) is generally referred to as a keyhole. The cushion body (2) is formed of a closed cell foam laminate having an upper layer (6) formed of a foam having a density of 48-52 kg/: and a hardness of 100-125 (BSS4443 Part 1 method 2988). This foam has a depth of about 50 mm, and overlies a lower foam having a depth of about 15 mm and formed of reconstituted chipped foam (6 lbs).

The projection portions of the channel (4) adjacent the cut-out (3) forms projections (8) which confer on the cushion the ability fully to support the posterior thigh portions, and the forward end of the pelvis for maximum supportive effect. Projection portions (8) are hollowed slightly in the 15 mm of the lower foam so that body conformation can be taken more into account.

It will be appreciated that the joint action of the thighs and the thigh bones and the lower forward area of the pelvis are able to transfer more weight to this projection area when the forward component of sitting down is applied thereto than in the case when the cut-outs (8) are not provided. Nevertheless, even if these modified areas (8)are not provided, the projections function beneficially.

Tests have shown that in the dotted area to upper portion of the cut-out (3) the pressure ordinarily transferred to the ischium will be in the order of 25 mm/Hg whereas the pressure transferred to the posterior thigh portion is of the order of 70 mm/Hg; still below the maximum safe levels.

As will be seen in Figure 2, the cushion (1) of Figure 1 is overlaid by a toweling cover which is generally slightly larger than the cushion itself to allow for a little relative movement.

In use, the thigh bones and pelvis are positioned on the cushion of Figure 1 as shown therein in the sitting condition, thereby to impart to the skeletal frame and and the tissue surrounding it a minimum of point loading.

Claims (7)

CLAIMS.

1. A substantially U-shaped cushion for medical purposes, said U-shape defining a central channel; characterized in that the average width of the channel is significantly less than the diameter of a generally circular cut out area in which the channel terminates; thereby to define opposed projection portions at the conjunction of the channel and the cut out area.

2. A cushion according to Claim 1 characterized in that to the opposed projection portions have areas at least of a reduced thickness thereby to assist in weight transfer.

3. A cushion according to either preceding claim characterized in that it is formed of a laminated foam, an upper foam of a softer and thicker material and a lower foam of a harder and thinner material.

4. A cushion according to any preceding claim characterised by a web between opposed ends of leg elements defining the channel.

5. A cushion according to claim 4 characterized in that the web is formed by an overall covering.

6. A cushion according to any preceding claim having an overall width of between 40 and 50 cm.

7. A cushion substantially as hereinbefore set forth with reference to and/or as illustrated in the accompanying drawings.