CA1077173A

CA1077173A - Fluid mattresses

Info

Publication number: CA1077173A
Application number: CA287,209A
Authority: CA
Inventors: Leslie A. Hopkins
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-09-23
Filing date: 1977-09-21
Publication date: 1980-05-06
Also published as: GB1545806A

Abstract

ABSTRACT OF THE DISCLOSURE

An air inflated mattress comprises, in combination, a plurality of inflated cells and constraint means of flexible material for encircling the cells so as to retain them in position whereby the cells form a resilient surface.
The constraint structure has a floor portion and a wall portion extending around the periphery of the floor portion. End parts of the wall portion are stiffened by end-boards and a base structure of articulated form is disposed on (or in) the floor portion. The cells are preferably formed so as to allow inflation fluid to bleed therefrom and may be covered with removable shrouds.

Description

1077~73 BACKGROUND TO THE INVENTION
This invention relates to fluid mattresses.
Although the invention is primarily concerned with fluid, (for example, air), mattresses to provide yielding support for a recumbent human body, as used herein the term "mattress" is intended to include resilient cushions, seats and chairs, in particular wheel chairs.
Furthermore~ a mattress according to the invention may be used to support any form of load, including loads other than a human body.
As explained in a paper by J.T. Scales and L.A. Hopkins, ("The Lancet", 23rd October, 1971, pp 885-888), when a person is confined to bed, small areas of soft tissues are compressed between the skeleton and the supporting surface. The load per unit area can be reduced by nursing the patient on a deformable, (e.g. spring), mattress, but it can still be great enough to compress blood-vessels and damage tissue.
The skin of a supine patient on an ordinary hospital bed may have to sustain loads of up to 150 mm. Hg (2.9 lb per sq.in). Capillary pressure, normally around 26 mm. Hg, is much reduced in the debilitated or seriously ill patient. With pressures above 78 mm. Hg applied to the skin, patients have complained of pain, and such loads collapsed capillaries ~` and veins. These pressures may cause transient circulatory disturbance, definite superficial and circulatory tissue damage, or, finally~ deep penetrating necrosis involving subcutaneous tissues, fascia, muscle, `, and bone, usually over the sacrum and trochanters.
Skin can also be damaged by shear stresses from friction between skin and bedding, especially when the patient is lying with his centre of gravity in such a position that he tends to sllde on the bed. A
further cause of skin breakdown and wound infection is the lack of evaporation of water.
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'10'~7~73 The prevention of bedsores is a major nursing problem, and the general nursing care of such patients (notably when they are obese) puts a considerable physical strain on nursing staff.
Taking the physiological and nursing needs together, the main requirements of a patient-support system are for automatic deformation of the support medium to accommodate body forms, uniformity of load, evaporation of water from the support area, controlled temperature and humidity of the patient's environment, and easy nursing (no lifting, mechanical ad~ustment of the patient's position, ease of collection of excreta, and ease of disinfection).
It has been proposed, (see the paper by J.T. Scales, "The Lancet", 1961, ii, 1181), that abody could be uniformly supported by air at pressures which would not cause undesirable physiological changes and that a patient-support system could be developed which would meet these requirements. The present invention seeks to provide an improved form of mattress which will give such support, either for long term bed patients, or to ensure a comfortable 'lride" for patients being transported.
SUMMARY OF THE INVENTION
According to the invention, a fluid mattress is of elongated plan form and comprises, in combination, a plurality of inflatable cells also of elongated plan form, the cells being disposed side by side in a row edtending along the longitudinal axis of the mattress, together with constraint means encircling the cells so as to retain them in position with their upper ends exposed whereby said upper ends form a resilient ~;
support surface, each cell having a width greater than its depth.
The inflatable cells may comprise groups of cells, the cells of each group being made integral with each other.
The constraint means may comprise a structure of flexible sheet materiai having a floor portion and a wall portion extending around the ~' . ' " -: ~' ' '. ' ' ' ' ~ ' ' ~,~t~7173 periphery of the floor portion. end boards may be provided.
The mattress of the invention may be used as a bed or a trolley, for example, a hospital bed or trolley, and is particularly useful for geriatric patients.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein :-Figure 1 is a side view, in medial section, of a mattress disposed on a hospital trolley, and illustrates a first embodiment, Figure 2 is a plan view of the mattress, Figure 3 is a section, taken on the lines III-III of Figure 1, and with added detail, Figures 4 and 5 are side and plan views respectively, of one inflatable cell, Figure 6 is a side view cf the constraint means, Figure 7 is a plan view thereof, Figure 8 is a plan view of an external support structure, Figure 9 is a front view of an end board, Figure 10 is a plan view of an internal support structure, Figure 11 is a perspective view of a second embodiment, Figure 12 is a side view, in section, of a mattress cell thereof, Figure 13 is a view in perspective of a cell-restraint toggle, Figure 14 is an end view, in section, of a mattress cell and cover, Figure 15 illustrates how the embodiment of Figure 11 can be articulated, Figure 16 is a perspective view of a third embodiment, and Figure 17 is a side view, in seceion~ illustrating a modification.
In the figures, like reference numerals, (e.g. 10, 110, 210), refer to like components.

~ - ` 5~ ~771'73 DI~AIT~ DEaCRI~IOl~S O~ E P~i~R~D 330Dli~NTS
~ith reference to FiOures 1 to 10, a fluid mattress 1 is of elongated plan form, and of demountable construction. The mattress 1 comprises, in combination, a plurality (eighteen) of (closed) inflatable cells 2 also of elongated plan form, the cells 2 bein~
disposed side by side in a row extending along the longitudinal axis 4 of the mattress 1. Constraint means 3 are provided which, (as shown), encircle the cells 2 so as to retain them in position with their upper ends exposed, whereby said upper ends form a resilient support surface for a recumbent human body. It will be noted that each cell 2 has a width greater than its depth and a depth greater than its thickness.
The mattress 1 has an oblong plan form. The ~nflatable cells 2 comprise four groups, namely A, ~, C and D, the cells of each group being made integral with each other.
The cells 2 are of nylon coated with rubber or polyurethane.
P.V.C. (Polyvinylchloride) is another suitable material. Each pair of cells is made from two sheets, bonded together back to back. Each sheet is then folded over, in opposite directions, and the oontiguous edges of each sheet welded together at 5. (See Figures 4 and 5). The cells 2 of each group are interconnected by communication apertures 6.
The cells 2 are of uniform size. (Widt'l 23"; depth 10"; thickness 4 With particular reference to Figures 6 and 7, the constraint means

3 comprises a collapsible structure of generally rectanOular plan form The structure is made from flexible sheet material, (P.V.C./Nylon) and has a floor portion 10 and a continuous wall portion 11 extending around the periphery of the floor portion. Further flexible sheet material is attached to the end parts of the wall portion 11, so as to form internal pockets 12, 13 with open lower ends. Tne pockets 12, 13 are used to retain a pair of pl~ood end boards 14 (Figure 9). The C~ .
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,- , - 5a end boards 14 prevent inflation forces from causinS the end parts of wall portion 11 to assume semi-circular profiles, (when viewed in plan). The end boards 14 thus stiffen the end parts of wall portion 11.
~he mattress is provided with a resilient base structure disposed inside the oonstraint means 3. The resilient base structure comprises base portions 15a, 15b, 15c of uniform width (22") by varying length (20"; 20.5"; 32.5").

' ~077173 -- _ 6 q`he resilient base portions (see Figures 1 and 10) comprise rectangular-shaped slabs of foam plastics material covered in P.V.C.
The mattress 1 is disposed on a hospital trolley 20 of standard (articulated) design. (See Figures 1, 2 and 3). q'he mattress 1 is supported on the upper part of the trolley 20 by a three-piece base structure of al~llinium, (see also Figure 8), comprising base portions 21a, 21b, 21c. q'he base portions are of uniform width (22") but vary in length (20.75"; 19.75" and 3~.25").
~he base portions 21a, 21b, 21c are of corrugated form, so as to provide a lightweight but strong structure. ~he edges of the base portions carry protective strips 22 (Figure 8).
q'he trolley 20 carries a bottle 25 of pressurised air. (Figure 1).
q`he bottle 25 is connected to an air distributor 26 by a flexible duct 27. ~he distributor 26 has a four-way selection switch 28, a pressure gauge 29~ and flexible outlet ducts 30.
The cells 2 are in four groups, and are connected to the ducts 30 by flexible ducts 31 and demountable connections 32. q'he ducts 31 have individual bleed valves 33.
With reference tc Figul~e 3, the upper portion of the trolley 20 is recessed, and the trolley is provided with a flexible sheet 35 covering the recess so as to form a "floor" or lining. q'he edges of the sheet 35 are releasably attached, by hooks 36, to adjacent parts of the trolley.
Figure 3 also shows how the m~ttress 1 is releasably attached, by hooks 40~ to adjacent parts of the trolley 20.
In use, the trolley 20 can be e-mployed normally, i.e. without the mattress 1. In this mode of operation, the recess lined by the sheet 35 can be used to store the mattress in a colL~psed condition~ with cells 2 deflated and folded, and with the constraint structure 3 folded .
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also, with the end boards 14 and base portions 15a, 15b, 15c contained - therein. The base portions 21a, 21b, 21c are then placed on top. The stores componenes can then be covered by the usual mattress carried by the trolley.
To bring the mattress 1 into use, the components are removed from storage, the base portions 21a, 21b, 21c placed on top of the trolley and the constraint structure 3 placed on top of the base portions.
The end boards 14 and base portions 15a, 15b, 15c are next placed in position, followed by the groups (A, B, C, D) of deformable cells 2.
The connections 32 are then used to connect the ducts 30 to the - ducts 31 and the distributor 26 employed to inflate each group of cells 2 in turn, using the pressure gauge 29 to make sure each group is inflated to the required pressure.
As they are inflated, the cells 2 swell to fill the constraint , 15 structure 3 and to tauten the sides thereof, whereby the cells 2 areheld firmly in the resilient "pocket" formed by the structure 3.
To support a man of average weight, inflation pressures of between about 15 to 50 lbs per sq.ft. are used. To be more specific, due to their varying densities, it is found that the pressure in the middle two groups (B, C~ of cells intended to support the trunk and thighs of the body require to be inflated to pressures of the order of 50 and 35 lbs per sq.ft. respectively, and the groups of cells supporting the legs (A) and head (D~ required to be inflated to a pressure of approximately 1~ lbs per sq.ft. Apart from it being necessary to vary the pressure between groups of cells 2 supporting the different parts of the body, so as to ensure that the pressures that will be built up therein will in fact support the body, it is also desirable that the pressure should be varied, so that the body is supported in a comfortable attitude.
The required adjustment of the pressure in the groups of cells 2 can ' 7~

readily be effected by appropriate adjustment of the bleed valves 33, either before or during use~
In operation, inflation pressures of the deformable cells 2 are adjusted so as to allow the cells to conform to the shape of the body whilst supporting it. Thus the cells 2 provide substantially uniform thrust per unit area and local pressure areas, (which result in bed sores), are avoided.
To increase the comfort of the body, the articulated trolley 20 can be adjusted so as to vary the attitude of the body. The construction of the structure 3 allows this articulation to take place, whilst ;
continuing to retain the cells 2 in place.
The mattress of the invention provides a comfortable bed for a human body, reducing any tendency for the formation of bed sores, and is thus particularly useful for use with geriatric patients.
Should a bed-pan be required, this can be slipped between cells 2 and beneath the patient. The cells can be removed for cleaning.
The limbs and other parts of the body can be exercised by opening and closing one or more of the valves 33 whereby the inflation pressure of the associated group(s) of cells 2 is raised and lowered, resulting in vertical movement of the body limbs.
The air bottle 25 may be replaced by an air blower unit, so as to provide a substantially continuous supply of cell inflation air.
With this modification, the cells 2 may be made of porous material whereby a steady bleed of inflation air is allowed to take place from within the cells, this atmosphere-seeking flow of air being used to remove body perspiration. In addition, this flow of air, by appropriate control of its temperature, can be utilised to cool or warm the body.
If a non-porous material is used for making the cells, the latter can be made porous, for example, by running cell material through a . ~ .
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- ~77~73 sewing machine, but without using thread~ so that the needle of the machine makes air esca?e holes in the ma-terial.
I~rith the cells 2 in the constraint struc-ture 3~ the latter provides a simple but effective way of retaining the cells in position whereby they forrl a resilient support surface. Furthermore, the construction of the structure 3 allows full articulation of the trolley 20, whilst retaining the cells 2 in position.
In a simplified modification, the ducts 31 attached to the cells 2 may be adapted to be inflated by a hand or foot-operated pump, for example~ the bellows-type pump used to inflat "LIL0" (Registered Trade llark) air-beds.
If the constraint structure 3 were not collapsible, it would be difficult to remove an elderly patient therefrom should one or more of the cells 2 become deflated, either intentionally or accidentally.
A modified bed structure (100) employing a fluid mattress 101 is shown in Figures 11 to 15. The cells 102 of this embodiment are not ; integral, but are discrete. However, adjacent cells 102 are joined together by snap connections attached to apertures 106. Furthermore, with this arrangement, end portions of the discrete cells 102 are demountably attached to side parts of the fabric wall portion 111 by toggles 150.
The toggles 150 comprise short-length rods 151 attached to the cells 102 by flexible strips 152 of fabric and insertable through eyelets 15 formed in the wall portion 111.
Inflated tubes 160 are disposed lengthwise along the upper edges f the side parts of the wall portion 111. Thc ends of the tubes 160 are held in position by elastic ties 161 extending across the end boards 114.
The tubes 160 provide a soft top edge to prevent patients rolling off the mattress 101. mhe elastic ties 161 allow the height of the ~077173 tubes 160 to be adjusted ~d also allow the tubes 16G to be pulled away, in order to obtain access to a patient.
With reference to Fi~ure 15, the mattress 101 can be erticulated to val~ the at1;itude of a body supported therebr9 whilst maintaining, for example, back or knee support. One or more inflatable structures 170 can be used to ~ack up parts of the base portions 115a etc. and an articulated attitude maintained by pivotable struts 171 located in grooves 172 formed in a base 173. As shown in Figure 15, the tubes 160 distort to allow articulation of the mattress.
In the case of the mattress 101, the floor portion (110) of the constraint structure is double-walled so as to form a "pocket" to receive the base portions 115a, 115b, 115c. The bnse structure formed by base portions 115a, 115b, 115c is of articulated form and is preferably padded.
Inflation air is supplied to groups of cells 102 by way of ducts 130/1~1 connected to a manifold 175. The manifold 175 is provided with individual flow control valves 176 and æir pressure gauges 177. Inlet duct 127 is connected to a blower 178. A heat exchanger 179 (heater and/or cooler) is provided in the air inlet line. Apertures 193 are provided for ducts 131.
If the cells 102 are to be "closed", the manifold 175 is also provided with individual relief valves to enable cell inflation pressure to be adjusted.
Alternatively, and as shown in Figure 12, the cells 1~2 can be perforated by bleed holes laO, to remove body perspiration. As shown in Figure 14, to prevent the supported body from "blocking-off" the bleed holes~ the (discrete) cells 102 may be covered with individual cotton shrouds 181 disposed over the cells so that the shroud-ends overlap.
The overlapping ends of the shrouds are preferably secured together, in .
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~Q~7173 a demountable manner, by "VELCR0" (Registered Trade Mark~ fasteners 182. Parts of the shrouds 181 may be cut away to facilitate fitting of the shrouds over the cells.
Figure 16 illustrates a stretcher structure 200 for use with an air and/or road ambulance. The mattress, which is identical to mattress 101 of Figure 11 etc., has been removed for reasons of clarity.
The side parts of wall portion 211 have fabric tubes 290 attached to them, so as to accept stretcher poles. Adjustable straps 291 are also attached to the wall portion 211, so as to enable a patient to be secured.
In this embodiment no base portions, (such as base portions 15a, 115a etc.) are required, and the floor portion 210 is perforated, by holes 292. The holes 292 provide for drainage of fluid. To conserve air, the cells of the mattress used with stretcher 200 are preferably not provided with bleed holes. Cell inflation air can be provided by a portable blower and air bottle, or a manually-operated air pump. me use of an air heater and/or cooler is optional. "Trailing" ends of air inlet ducts extending through apertures 293 may be disposed in short lengths of fabric tubing, (not shown), extending along the sides of the structure 200.
Figure 17 illustrates a modification of the air-feed system illustrated in Figure 11.
With reference first to Figures 11 and 12, the method of adjusting inflation pressures of perforated cells 102 by controlling the volume of air supplied to each group, although it works satisfactorily, means that the volume of air passing through the cells can only be the volume of air escaping through holes 180. This means that should the mattress temperature be changed by passing inflowing air through a heat exchanger, there is a significant delay before the temperature can become ~ 77173 ~ 12 substantially uniform over all of -the mattress. ~is c~n be corrected by feeding the air to esch group of cells 102 by way of a coaxial duct arrangement.
Tl~ith reference to Fi~lre 17, air is fed to each group of cells 102 by way of an ~nnular passagewa~ defined by inner (190) c~d outer tl30a) coaxiclly disposed duots. ~he inner duct 1"0 collects excess air and brings it back to vent valves 191 mounted on the manifold 175a~ where these valves control the voluiJIe of air vented to atmos7-here and therefore control cell group pressure. 3y this arrangement9 a large volume of air can be discharged into the cells 102, so as to make a rapid change in mattress temperature.
To mc~e it easier for a nurse or patient to control cell group pressure, an airflow control valve 192 is fitted in the air inlet duct 127a. ~he vent valves 1~1 on the manifold 175a are pre-set to give the correct cell pressure when sitting upright on the mattress.
The patient then only needs to adjust the air inlet valve 192 so as to get a more comfortable mattress pressure, i.e. by closin~ the valve to obtain a "soft'bed.
To reduce the noise of air escaping to atmosphare by way of vent valve 191, a soundproof box 194 is preferably fitted to the outlet side of the valve.
Any of the above-described features may be used, where practicable, in combination with each other, or one may be used as a substitute for another. For example, the blower 178 of Figure 11 ma~ be used with the mattress of Figure 1, instead of the air bottle 25 referred to, and the tubes 160 ~nd elastic tieæ 161 of Figule 11 may be used with the mattress of Figure 1.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fluid mattress of elongated plan form, comprising, in combination, a plurality of inflatable cells also of elongated plan form, the cells being disposed side by side in a row extending along the longitudinal axis of the mattress, together with constraint means encircling the cells so as to retain them in position with their upper ends exposed whereby said upper ends form a resilient support surface, each cell having a width greater than its depth, and a depth greater than its thickness, the inflatable cells comprising groups of cells, the cells of each group being made integral with each other, and inflatable to pressures different from those of other groups.

2. A mattress as claimed in Claim 1, wherein the constraint means comprises a structure of flexible sheet material having a floor portion and a wall portion extending around the periphery of the floor portion.

3. A mattress as claimed in Claim 2, wherein end parts of the wall portion are stiffened by end-boards.

4. A mattress as claimed in Claim 1, provided with a base structure.

5. A mattress as claimed in Claim 2, provided with a base structure.

6. A mattress as claimed in Claim 4 or 5, wherein the base structure is of articulated form.

7. A mattress as claimed in Claim 1, wherein the cells are formed so as to allow inflation fluid to bleed therefrom.

8. A mattress as claimed in Claim 2, wherein the cells are formed so as to allow inflation fluid to bleed therefrom.

9. A mattress as claimed in Claim 7 or 8, wherein the cells are covered with removable shrouds.

10. A bed provided with a mattress as claimed in Claim 1 or 2.

11. A stretcher provided with a mattress as claimed in Claim 1 or 2.