GB2387114A

GB2387114A - Patient support structures

Info

Publication number: GB2387114A
Application number: GB0207596A
Authority: GB
Inventors: Patrick Noel Daly
Original assignee: SAREO HEALTHCARE Ltd
Current assignee: SAREO HEALTHCARE Ltd
Priority date: 2002-04-02
Filing date: 2002-04-02
Publication date: 2003-10-08
Also published as: GB0207596D0

Abstract

Patient support structures in the form of mattresses, pads or cushions, the structures comprising a plurality of air, bladders, a body of foam material over the bladders and coupling parts 30a 30b for connection to a control system 3 for selectively inflating and deflating the bladders. The structures are provided with a non-return valve 32 which allows the bladders to be partially inflated to a pre-determined level for static use of the support structure and for the control system to be disconnected and used with another support structure, such that one control system can be used in conjunction with many support structures. The structure is suitable for use in the treatment and prevention of decubitus ulcers.

Description

:: i:--::: 23871 1 4..DTD: Improvements in or Relatina to Patient Support

Structures and their Use The present invention relates to the prevention or treatment of pressure sores and pressure ulcers, and in particular to equipment used in therapy related to pressure 5 sores and pressure ulcers, and to methods of using that equipment.

Pressure sores and pressure ulcers (hereinafter, pressure ulcers) are unfortunately common in patients who are required to lie in the same position for long periods of time, for example because of the nature of their illness or infirmity. The weight of a 10 relatively immobile patient lying on a flat surface such as a conventional mattress tends to be concentrated on certain areas of the body, in particular the sacrum and the heels. The pressure on the skin and tissues in these areas caused by the patient's weight limits the flow of blood to these areas, so limiting the input of nutrients and also limiting the transport away of waste products. This can result in necrosis of the 15 tissues in these areas.

In order to treat pressure ulcers, or to prevent them from forming, conventional therapy aims to reduce the pressure on the key regions such as the sacrum or heels by, for example, distributing the patient's weight over a wider area. This is done by 20 increasing the contact area of the patient with the underlying mattress and a variety of mattresses aiming to achieve this result are known. Such mattresses may be referred to as static mattresses, in contrast to dynamic mattresses discussed below.

Another approach to the treatment of pressure ulcers, often used in more severe 25 cases, is the use of so-called dynamic or alternating pressure mattresses. These mattresses include a plurality of individual bladders which are subjected to an inflation and deflation cycle which thus varies with time the pressure experienced by the various parts of the patient's body, thereby relieving the key areas most prone to pressure ulcers. A typical alternating pressure mattress will include two rows of air 30 filled tubes (bladders) side by side, mounted on a suitable base. Typically between 12 and 20 air tubes are provided and a pump controller unit inflates and deflates the tubes in a sequence where tube A will inflate and adjacent tube B will deflate. In

- : A-:c:.

^:- : another known sequence, tubes A and B inflate while tube C will deflate. These cycles are repeated under the control of a timing circuit in the pump controller. The pump controller, which will normally include the pump; a timer and a series of solenoids for opening and closing air paths in and to the mattress, is usually mounted 5 on the end of the hospital bed and is never disconnected from the mattress while the mattress is in use. The pump controller may include a Programmable Logic Controller or a simpler timer based switching system, as appropriate.

A particularly successful example of a dynamic mattress is Sareo Healthcare Ltd's 10 Airform (_) mattress, as described in GB 2 346 553. This mattresses comprises a series of alternating pressure bladders surmounted by a visco-elastic foam layer and overcomes many of the problems of conventional dynamic mattresses, some of which are outlined below. The contents of GB 2 346 553 are hereby incorporated by reference in their entirety.

Conventional dynamic (alternating pressure) mattresses have a number of limitations. The mattress cannot be used separately from the pump controller as patients would experience movement of the air tubes (ie movement of air in the tubes) even when the mattress is not alternating, giving an unpleasant and 20 uncomfortable "floating" sensation. Because of the construction of the mattress with the upper surface of the air tubes forming in effect the face of the mattress on which the patient lies, the mattresses are difficult to clean. Frequent removal of the mattresses for specialist cleaning and decontamination is needed to remove any human waste products such as urine and farces, or blood, which may fall between 25 the air tubes. Further, if the mattress is not alternated by the pump controller, there is a danger that patients may be able to slip between the cells which, apart from being uncomfortable, promotes the occurrence of pressure ulcers since the patient is then effectively lying on the hard supporting under-surface of the bed. This problem is even worse in beds with four-section profiling surfaces which can be adjusted into a 30 chair like position to enhance circulation in patients with cardiovascular conditions.

In such a configuration the air tubes of a conventional dynamic mattress can easily separate allowing the patients to slip through to be supported only by the bed base or

c i' t;r ret À* À À frame. Because of its advantageous constructions the mattress of GB 2 346 553 does not suffer from these disadvantages. Conventionally also, dynamic mattresses are not provided with any means to retain air in the air tubes if the pump controller is disconnected. Equipping a hospital, treatment centre or care home with alternating pressure mattresses is expensive. The available systems can cost between ú2,000 and ú12,000 per bed. Considering the example of a newly built long stay hospital with SO beds and which cares for high to maximum dependency elderly patients, under normal 10 circumstances it is necessary to have as many alternating pressure mattress systems as possible to cater for all patients. Typically in this example, it would be normal to have 30-35 dynamic mattress systems. For a one-off purchase this might cost from about ú70,000 to about ú200,000, or even more. This represents a major capital investment and it is an aim of the present invention to minimise the requirements for 15 this investment.

According to a first aspect of the present invention, there is provided a support structure for use in the treatment or prevention of pressure ulcers, the support structure comprising: 20 a plurality of inflatable bladders defining a support surface for supporting a patient, the bladders being adapted for selective inflation and deflation; a covering layer covering at least a portion of the support surface and comprising a body of supporting foam material; a coupling part for releasably coupling said bladders to a control system 25 adapted to supply pressurised air to the bladders for said selective inflation and deflation; and at least one non-return valve for isolating said bladders when said control system is not coupled, to retain air in the bladders.

30 In one variation of this aspect of the invention, the support structure is a mattress. In an alternative variation the support structure may be a pad or cushion.

. In a particularly preferred embodiment of this aspect of the invention, the body of supporting foam material is a visco-elastic foam.

Preferably, the covering layer covers substantially all of the support surface.

Preferably also at least the upper surface of the covering layer is covered by a cover of a polyurethane material.

According to a second aspect of the present invention there is provided a treatment 10 system comprising the combination of a support structure according to the first aspect of the invention and a control system, said control system comprising an air pump, a coupling part for releasably connecting to said coupling part of the bladders of said support structure and inflation control means for controlling the selective inflation and deflation of the bladders, said control system further comprising means 15 for causing equalization of the pressure to a predetermined pressure in all said bladders prior to disconnection of said coupling parts.

In a particularly preferred embodiment, said control system equalises the pressure in said bladders to at least 70% of the maximum operational pressure. Preferably said 20 control system equalises the pressure in said bladders to 75% to 80% of the maximum operational pressure.

According to a third aspect of the present invention there is provided an establishment for the treatment or care of patients suffering from or susceptible to 25 pressure ulcers, said establishment comprising a first number of the support structures according to the first aspect of the invention and a second number of control systems comprising an air pump, a coupling part for releasably connecting to said coupling part of the bladders of said support structures and inflation control means for controlling the selective inflation and deflation of the bladders, said first 30 number being greater than said second number.

À À À

À. Most preferably said control systems comprise means for causing equalization of the pressure to a predetermined pressure in all said bladders prior to disconnection of said coupling parts.

5 According to a fourth aspect of the present invention there is provided an assembly . composing: (a) one or more combinations, each combination comprising a first support structure according to the first aspect of the invention and a control system comprising an air pump, a coupling part releasably coupled to the coupling part of 10 the bladders of said support structure, and inflation control means for operatively selectively inflating and deflating the bladders of the support structure, and (b) one or more second support structures according to the first aspect of the invention not coupled to a said control system and wherein each of said bladders is inflated to a predetermined pressure less than the maximum operating pressure of 1 5 bladders.

Preferably the bladders of the second support structures are inflated to a pressure of at least 70% of the maximum operational pressure, and especially to a pressure of 75% to 80% of the maximum operational pressure.

Most preferably the control system further comprises means for causing equalization of the pressure to a predetermined value in all said bladders of the first support structures prior to disconnection of said coupling parts.

25 According to a fifth aspect of the invention there is provided a method of managing the treatment of a plurality of patients suffering from, or susceptible to, pressure ulcers, the method comprising the steps of: (i) assessing the clinical risk or extent of pressure ulcers for a given patent and, 30 (ii) if the risk is below a predetermined threshold value: (ii)(a) providing a treatment system according to the second aspect of the invention; s

I' Or À Me (ii)(b) inflating the bladders of the support structure to a predetermined pressure; and (ii)(c) releasing the coupling parts of the support structure and the control system to disconnect the control system from the support structure, or 5 (iii) if the risk is above a predetermined threshold value: (iii)(a) providing a treatment system according to the second aspect of the invention and setting said control system to selectively inflate and deflate the bladders of the support structure.

10 Thus, the present invention provides a means whereby the capital cost of equipping a facility for the treatment or care of patients susceptible to or suffering from pressure ulcers can be considerably reduced since it is no longer necessary for each dynamic mattress to be provided with a control system. Because of the construction of the mattress according to the invention, the mattress can be used in either of two ways.

15 Firstly, for lower risk patients the mattress can be used as a static mattress. The bladders of the mattress are first inflated using the control system so that all the bladders are inflated to a predetermined pressure, which is ideally equal in all bladders. The control system can then be disconnected from the mattress and used as required with other mattresses. The construction of the mattress including the 20 covering layer of a body of supporting foam material (and especially where the supporting foam material is a visco-elastic foam) allows the patient to lie comfortably on the mattress without the uncomfortable "floating" feeling of conventional alternating pressure mattresses (when such mattresses are not in the alternating mode) and without danger of displacing the air tubes or bladders which 25 would cause the patient to come into contact with the bed base. This advantage is also achieved for beds which can be set in the cardiac chair position. The provision of the body of supporting foam material as the covering layer allows the mattress to conform to a great extent with the patient's body, so increasing the contact area of the mattress with the body through which the patient's weight acts and thereby 30 reducing the pressure on the patient's tissues in the key areas susceptible to pressure ulcer formation. Where the body of supporting foam material is a visco-elastic foam, this effect is very advantageously achieved. Visco-elastic foams are responsive to

r c' e Àebe- À : À À À body temperature and have the ability to "flow" to achieve an exceptional degree of conformity with the body (hence relieving pressure) whilst still being very supportive. 5 Secondly, for higher risk patients, the same mattress can be used as a dynamic (alternating pressure) mattress. In this case, the control systems remain attached to the mattress for the duration of the treatment to control the cycle of selective inflation and deflation of the bladders.

10 The comfort and safety of the mattress of the present invention in its static condition derives also from the ability to control the inflation of the bladders to a predetermined degree before the control system is disconnected, and to maintain that inflation after the control system has been disconnected. It is important that an appropriate inflation level of the bladders is set before the control system is 15 disconnected. If the inflation pressure is too high, this will cause excessive pressure on the tissues of the patient lying on the mattress, potentially leading to pressure ulcer formation. Equally, if the pressure is set too low, the patient effectively becomes supported by the bed base and, although the covering layer comprising the body of foam material will mitigate this effect, effectively being in contact with the 20 bed base will lead to increased pressure on the tissues of the patient and potentially to pressure ulcer formation. Therefore, in the static mode, the bladders are inflated to a pressure less than the nominal maximum operational pressure achieved in the dynamic mode. In this case the nominal operational maximum pressure is the maximum pressure to which any given bladder is inflated during a normal selective 25 inflation and deflation cycle. Typically, to provide adequate support for a patient without the danger of excess pressure from over-inflation, the inflation of the bladder in static mode is set at least 70% of the nominal maximum operational pressure, preferably about 75% to 80% of said nominal maximum operational pressure.

Having set the desired inflation pressure for the bladder, the control system is 30 disconnected. The mattress of the invention includes means, in particular a non return valve, for ensuring that the inflation of the bladders is maintained after the control system has been disconnected. The non-return valve may be connected to, or

^ '1 À. À À

incorporated in, the coupling part which connects to the coupling part of the control system. The flexibility of use of the mattress according to the invention allows a treatment 5 establishment such as a hospital or nursing home to be equipped with the same mattress for all its beds since the mattress is suitable for all types of patient - that is, those at no risk of pressure ulcers, those at low risk of pressure ulcers and those at high risk of pressure ulcers. Because the control system is disconnectable and is therefore useable at different times with different mattresses, the requirement for 10 control systems is reduced. The control systems are transportable and interchangeable and can be used both for inflating mattresses to a predetermined extent for static use and for controlling the inflation and deflation cycle for dynamic use of the mattress.

15 Taking again the example of a newly built hospital of 50 beds, each bed can be equipped with a mattress according to the invention at a cost of about ú25,000 to ú40,000. Because the control systems are interchangeable and transportable, and because not all patients will require a mattress in its dynamic mode, it would be sufficient to provide about 20 individual control systems at a cost of about ú30,000.

20 In this way, the cost of fitting out the new hospital could be reduced from an average of ú135,000 to about ú62,500, amounting to a very significant cost saving of the order of 50%. It is also worth noting that the characteristics of the mattress of the invention in its static mode are superior to those of a standard hospital mattress (which might otherwise be used for low risk patients) and so the comfort and 25 protection from pressure ulcers for patients is greatly enhanced.

For a better understanding of the invention and to show how the same may be carried into effect, reference will be made to the following drawings, in which: Figure 1 is a schematic cross section through a mattress according to the invention; 30 Figure 2 in a schematic cross section through another mattress according to the mventon; and

c.:.-: À e Figure 3 is a schematic perspective view of a mattress according to the invention, showing the bladders removed.

Referring now in particular to Figure 1 which comprises a series of inflatable 5 bladders (1) each in the form of a tube. The tubes, in combination, define a support surface for supporting a patient.

The inflatable bladders (1) are preferably manufactured from hydrophobic polyurethane material. The stretch in the material ensures full patient conformity 10 and reduces shear forces on the skin tissue. These shear forces are also an important contribution to the formation of pressure ulcers.

Typically the bladders are approximately 90cm in length and 14cm in diameter. This depends upon mattress size and clinical/patient requirements.

The inflatable bladders (1) are connected via air lines (2) and coupling parts (30a, 30b) to a control system (3). The control system is adapted to (3) selectively supply pressurized air to the bladders (1) to control their inflation and deflation.

20 In use of the mattress in its dynamic mode the control system (3) inflates and deflates each bladder (1) independently. Typically AB or ABC alternating cycles are used.

In an AB alternating cycle each bladder (1) is inflated and deflated out of phase with its neighbour. In an ABC cycle bladder A and B inflate whilst C deflates, then B and C inflate whilst A deflates and so on. A cycle time of the order of 6 minutes is 25 typically selected for high risk patients. Such cycles ensure that the points of contact between the patient and mattress vary over time, so assisting in the healing or prevention of pressure ulcers.

The maximum and minimum air pressures in the air bladders (1) during each cycle 30 can be varied by programming the control system (3). This is to allow for patients of different weights.

t' À À r e e e , e C À.. In use of the mattress in its static mode, the control system (3) is used initially to set the pre-determined pressure in all the bladders (1). Inflation of the bladders to this pre-determined pressure can take as little as one minute, after which the coupling parts (30a, 30b) are used to disconnect the control system (3) from the mattress. The 5 control system may be adjustable or programmable to vary the pre-determined pressure in accordance with the particular clinical needs of the patient. Also, preferably the control system (3) is programmed to carry out the inflation of the bladders (1) to the predetermined pressure automatically when the operator presses a designated button. Interlocking means may be provided to prevent separation of 10 the coupling parts (30a, 30b) until the control system (3) has inflated the bladders (1) to the pre-determined pressure. A non-return valve (32) acts to prevent deflation of the mattress when the coupling parts (30a, 30b) are separated. The non-return valve (32) may be programmable and/or constructed to have its non-return function only when the coupling parts (32) are disconnected. The non-return valve (32) may be 15 formed integrally with the coupling part (30b).

Each bladder can be easily and immediately removed and exchanged if damaged or punctured. A pressure feedback sensor system (4) in the pump unit may be included to provide an audible and/or visual alarm (5) if a pressure drop due to bladder 20 damage is detected by the sensor.

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 alarm will be 25 activated. If this is not corrected then the audible alarm will be activated.

The bladder system may also preferably comprise two rapid deflation valves for rapid deflation of the mattress tubing. When opened these allow deflation of the mattress within approximately ten seconds. Such rapid deflation might, for example, 30 be needed if cardiac massage must be given to the patient.

À I l: t À À r. In the embodiment illustrated in Figure 1 the bladders (1) are embedded within a visco-elastic foam shell (7). The portion 7a of the foam shell forms the covering layer for the bladders. The foam shell is pressure sensitive. The foam typically has an uncompressed density of between 50kgm3 and 65kgm3, a hardness of 80-120N at 5 20 C, and is fire retardant. The foam is open celled and breathable.

The foam (7) also extends in walls (8) between the air bladders (1). For this type of foam the walls (8) are optimally between 10 and 20mm thick. Such walls (8) slowly absorb the forces exerted by the inflatable bladders (1) thereby reducing peak 10 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 lOmm thick the layer will compress too easily and the comfort aspect will be lost. If the layer is thicker than 20mm then the benefit of the inflatable bladders (1) is lost.

The foam (7) is sealed within a plastic polyurethane multi-stretch cover (9). The cover (9) is preferably 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 20 the foam (7) to escape through the cover (9).

The coating (10) 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.

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.

30 The base weave layer (11) typically has a weight of between 125 and 250gm2. The coating (10) typically has a weight of approximately lOOgm2.

-e. e À À À - r e.

The cover also has the advantage of giving the mattress the appearance of a standard hospital mattress, which can make it more acceptable to patients.

Shown in Figure 2 is a further embodiment of a mattress according to the invention, 5 shown in cross section. In this embodiment the foam layer (7) comprises two parts.

The first part (7b) defines a plurality of recesses into which the open bladders are inserted. The second part (7c) of the foam layer is in the form of a sheet which is attached to the first part as shown to cover the recesses.

10 The mattress preferably comprises a plurality 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.

15 Figure 3 shows the mattress of Figure 2 with the air bladders removed and illustrates in particular a preferred location of the coupling parts (30a, 30b) and the non-return valve (32).

Although the present invention has been principally described in connection with 20 mattresses, the principles of construction and use are equally applicable to other support structures such as cushions and pads, as might, for example, be suitable for use in wheelchairs.

Claims

r À r r r t. -

t CLAIMS..CLME: - 1. A support structure for use in the treatment or prevention of pressure ulcers, the support structure comprising: 5 a plurality of inflatable bladders defining a support surface for supporting a patient, the bladders being adapted for selective inflation and deflation; a covering layer covering at least a portion of the support surface and comprising a body of supporting foam material; a coupling part for releasably coupling said bladders to a control system lO adapted to supply pressurised air to the bladders for said selective inflation and deflation; and at least one non-return valve for isolating said bladders when said control system is not coupled, to retain air in the bladders.

15
2. A support structure as claimed in claim I comprising a mattress.
3. A support structure as claimed in claim l comprising a cushion.
4. A support structure as claimed in any of claims 1 to 3 wherein the body of 20 supporting foam material is a visco-elastic foam.
5. A support structure as claimed in any preceding claims wherein the covering layer covers substantially all of the support surface.

25
6. A support structure as claimed in any preceding claim wherein at least the upper surface of the covering layer is covered by a cover of a polyurethane material.
7. A treatment system comprising the combination of a support structure as claimed in any of claims l to 6 and a control system, said control system comprising 30 an air pump, a coupling part for releasably connecting to said coupling part of the bladders of said support structure and control means for controlling the selective inflation and deflation of the bladders, said control system further comprising means

e: À À r. e A. s for causing equalisation of the pressure to a predetermined pressure in all said bladders prior to disconnection of said coupling parts.
8. A treatment system as claimed in claim 7 wherein said control system 5 equalises the pressure in said bladders to at least 70% of the maximum operational pressure.
9. A treatment system as claimed in claim 7 wherein said control system equalises the pressure in said bladders to 75% to 80% of the maximum operational 1 0 pressure.
10. An establishment for the treatment or care of patients suffering from or susceptible to pressure ulcers, said establishment comprising a first number of the support structures as claimed in any of claims 1 to 6 and a second number of control 15 systems comprising an air pump, a coupling part for releasably connecting to said coupling part of the bladders of said support structures and control means for controlling the selective inflation and deflation of the bladders, said first number being greater than said second number.

20
11. An establishment as claimed in claim 1 0 wherein said control systems comprise means for causing equalization of the pressure to a predetermined pressure in all said bladders prior to disconnection of said coupling parts.
12. An assembly comprising: 25 (a) one or more combinations, each combination comprising a first support structure as claimed in any of claims 1 to 6 and a control system comprising an air pump, a coupling part releasably coupled to the coupling part of the bladders of said support structure and control means for operatively selectively inflating and deflating the bladders of the support structure, and 30 (b) one or more second support structures as claimed in any of claims 1 to 6 not coupled to a said control system and wherein each of said

À.-. . e m À À 5. a-. e -

. bladders of said support structures is inflated to a predetermined pressure less than the maximum operating pressure of bladders.
13. An assembly as claimed in claim 12 wherein the bladders of the second 5 support structures are inflated to a pressure of at least 70 /O of the maximum operational pressure.
14. An assembly as claimed in claim 13 wherein the bladders of the second support structures are inflated to a pressure of 75% to 80% of the maximum lO operational pressure.
15. An assembly as claimed in any of claims 12 to 14 wherein the control system further comprises means for causing equalization of the pressure to a predetermined value in all said bladders of the first support structures prior to disconnection of said 15 coupling parts.
16. A method of managing the treatment of a plurality of patients suffering from, or susceptible to, pressure ulcers, the method comprising the steps of: (i) assessing the clinical risk or extent of pressure ulcers for a given 20 patient and, (ii) if the risk is below a predetermined threshold value (ii)(a) providing a treatment system as claimed in any of claims 7 to 9; (ii)(b) inflating the bladders of the support structure to a predetermined pressure; and 25 (ii)(c) releasing the coupling parts of the support structure and the control system to disconnect the control system from the support structure, or (iii) if the risk is above a predetermined threshold value (iii)(a) providing a treatment system as claimed in any of claims 7 to 9 and setting said control system to selectively inflate and deflate the bladders of the 30 support structure.