EP0643572B1

EP0643572B1 - Improvements in or relating to air support systems

Info

Publication number: EP0643572B1
Application number: EP93913246A
Authority: EP
Inventors: Vera Caldwell; Kenneth Caldwell
Original assignee: Individual
Current assignee: CALDWELL, KENNETH; CALDWELL, VERA
Priority date: 1992-05-29
Filing date: 1993-05-28
Publication date: 2000-02-16
Anticipated expiration: 2013-05-28
Also published as: DE69327872D1; AU681084B2; GB2267217A; GB2267217B; EP0643572A1; DE69327872T2; WO1993024088A1; GB9311095D0; AU4337693A

Abstract

The present invention provides, in a first aspect, a force ventilated support system comprising an air support means together with a forced ventilation means. The invention also provides, in a further aspect, a multi-pressure air support system comprising an air support means together with multi-pressure zone means. The system of the further aspect may be used in combination with, or separately from, the system of the first aspect of the invention.

Description

The present invention relates to a zero-loss, multi-pressure, air support system, in the form of a mattress assembly.
It is well known in medical circles that low pressure air support systems are rated very highly in providing pressure relief to patients and elderly people who are at risk in developing pressure sores particularly, when confined to a bed for a long period of time.
There are various air support systems known including low loss air support systems, alternating pressure systems and static inflatable devices. There is particularly known a support apparatus comprising a frame with support members being mounted on such frame and a plurality of inflatable air sacs mounted on and operatively connected to such support members. Such beds usually have a low pressure air supply connected thereto, the pressure normally utilised being of the order of 25 mm Hg. The air sacs or air chambers are almost airtight but permit leakage at a planned rate from holes or stitch holes and the sacs may be linked together to form common pressure zones. Such arrangement enables differing pressures to be applied to the differing groups of air sacs or chambers so as to provide a patient with a comfortable support system. Moreover, the frame is in the form of sections, the angles of which may be adjusted to assist in the comfort of the patient.
Whilst such air support systems are well known and utilised in medical circles, the provision of totally air-tight sacs or chambers, particularly when grouped close together, do not allow for ventilation and can cause a patient to perspire heavily and become uncomfortably hot.
It is an object of the present invention to at least minimize the above-mentioned disadvantages.
EP-A-0292218 discloses an improved bed system having two inflatable bladders with a pre-set pressure differential therebetween and indicates the possibility of utilising a forced air ventilation system in one embodiment.
According to the present invention there is provided a zero-loss, multi-pressure, air support system comprising an air support means in the form of a mattress assembly having a first plurality of inflatable, air-tight, air sacs forming chambers which are connected together in at least first and second pressure zones, each of said pressure zones being operated at a pre-selected pressure, a specific pressure being selected for each zone, and multi-section pressure regulation means which operates to inflate said first pressure zone to a first pressure and operates to inflate said second pressure zone to a second pressure which is different from the first pressure, and further including forced air ventilation means;
characterised in that said forced air ventilation means includes a second plurality of inflatable air sacs with apertures forming second chambers, an air supply pump, and a manifold, said second chambers being connected to the manifold, said air supply pump providing a stream of air through the manifold to the inflatable air sacs, and said apertures providing a ventilation air stream.
In an embodiment of the present invention the mattress assembly comprises:
a first plurality of inflatable sacs which are completely air-tight connected together so as to form at least a first group and a second group of sacs, each group defining an individual pressure zone capable to operate at a different pressure; and
means for applying pressure to each group of sacs until each zone is inflated to a different pre-selected pressure; and
means for applying pressure to each group of sacs until each zone is inflated to a different pre-selected pressure;
and further including a second plurality of inflatable sacs with apertures defined therein; and
means for maintaining a continuous supply of forced air, said apertures providing a ventilating air stream.
The force ventilated support system according to the present invention has various advantages over the prior art, one distinct advantage being that the system of the invention is fail-safe and will not collapse when the power supply fails, the system continuing to support the patient as normal until resumption of the power supply takes place.
It will thus be seen that in the present invention, in one embodiment thereof, a force ventilated air support system is provided having a triple membrane arrangement, two of said membranes providing an air-tight inflatable air chamber or sac and the third, outer, membrane being connected at its edges to the edges of one of said other membranes, and having apertures therein to enable air to be forced out through said apertures.
It has been found that the present invention enables a low interface pressure between the body of a patient and the support system to be achieved. Utilising a Texas Interface Pressure Evaluator, it has been ascertained that an interface pressure of a bed incorporating a support system in accordance with the present invention provides an interface pressure of the order of 16-22 mm Hg, dependent on patient weight and physical characteristics.
In addition to being suitable as a support system for a bed, it is also possible to incorporate the force ventilated air support system of the present invention into a pillow for utilisation with a hospital bed. The pillow may have half its thickness filled with normal filling material and an inflatable core. Such core would be formed of a triple membrane arrangement as referred to above having apertures in the outer membrane. The two membranes forming the air-tight chamber or sac is firstly inflated to the required pressure. In this connection, the thickness of the pillow can be increased or decreased as desired by inflation of the airtight inner core. The pillow may be piped into the air supply system of the bed with which the pillow is being utilised and fresh air is then forced through the apertures in the outer membrane providing the required ventilation through the pillow. Such arrangement assists in preventing perspiration in the neck and head region of a patient.
The purpose of providing multi-pressure zones is to enable a greater degree of accuracy and fine control for the support of patients, for example, on inflatable support mattresses such as the zero air loss force ventilated support system as described in accordance with a first aspect of the present invention, a low air loss system as well as independent sac support air systems.
The provision of two or more pressure zones or strata provides a safety higher pressure lower level, combined with a low interface pressure and high comfort upper level.
It will thus be seen that in an embodiment of the present invention, wherein the air support means is in the form of a mattress or support surface, a multi-pressure zone system is provided therein which enables one portion of the mattress or support surface to operate at one pressure and another position to operate at a different pressure. Accordingly, depending upon the illness and/or injury suffered by a patient, the pressure of the support mattress or support surface can be modified along its length to provide extra comfort for a patient. It is believed that the present invention will have particular use in connection with providing pressure relief to patients and elderly people who are at risk in developing pressure sores, particularly when confined to a bed for a long period of time.
The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a perspective view showing a mattress system according to the invention;
Fig. 2 is a side view showing manifold to air sac connections;
Fig. 3 is a side view showing alternate manifold to air sac connections;
Fig. 4 shows a complete hospital type arrangement of the system;
Fig. 5 shows an air controlled bed unit;
Figs. 6 - 8 show a seat, seat back and seat back leg units;
Fig. 9 shows a multiple section manifold and mattress assembly;
Fig. 10 shows a three pressure zone arrangement;
Fig. 11 shows independent internal pressurized devices;
Fig. 12 shows a section including a low air loss support system;
Fig. 13 shows a three pressure zone bed; and
Fig. 14 shows the support system incorporated within a mattress cover.
Fig. 1 shows a series of air sacs or chambers 10 connected together in pressure zones 11. Such zones 11 are inflated or deflated by means of the inflation nozzle 12. The zones 11 remain at the pressure so set via the inflation nozzle 12 using air from a load support air supply into the common manifold 13 via the zone inflation nozzle 12.
A stream of ventilation air is provided via the ventilation air stream supply nozzle 14 to all the sacs 10 in common via the ventilation air stream supply manifold 15. The ventilation air stream is then evenly distributed along the full surface of the support system via air sac jets 16. In this connection, each air sac 10 preferably has a triple membrane form, two of said membranes forming an air-tight chamber into which air is supplied by means of manifold 13. The outer membrane of the sac 10 provides a space into which the ventilation air stream is supplied via manifold 15. The ventilation air stream then flows out of the air sac jets or apertures 16.
The system illustrated in Fig. 1 shows parts of a mattress system incorporating ventilation air stream apertures and is constructed in the manner indicated above.
Fig. 2 shows an alternative method of assembly utilising plug and socket means to connect the air sac and ventilation channels to the associated manifolds.
Fig. 3 shows another alternative method of air sac connection via plug and socket means.
Whilst the force ventilated system of the present invention can be provided as a simple support mattress or seating unit, the system will be now illustrated in combination with a typical full hospital style or nursing home bed unit as shown in Fig. 4. In such arrangement, the support system of the present invention is mounted on a rigid bed frame 41 having a hinged support top surface 42 by which means the angles and posture of the mattress surface can be adjusted. The power to adjust the angles or posture of the hinged support surface 42 is provided by an inflatable head bellows 43 and foot bellows 44. The control of the bed angles or posture is available to the patient or nursing staff by means of a hand control push button unit 45 such that when the button to raise the head end of the bed is pressed, air from the air unit 46 is diverted to supply air to the bellows unit 43 and when the push button to lower is pressed, air from bellows 43 is released to atmosphere, thus allowing the bellows 43 to lower the head section of the bed.
Air pressure to the air sac or chamber pressure zones 47, 48 and 49 are controlled in a similar manner to the head and foot bellows 43 and 44, using push buttons on the hand control unit 45.
The ventilation air stream is flowing continuously whenever the pump unit 46 is running via the ventilation air stream supply line 50 to the common ventilation air stream manifold 51 for distribution along the bed surface via the ventilation air jets 16.
The hand control unit 45 has two push button control valves for each operation required of the bed or seating unit. Air from the pump unit 46 passes continuously through the control unit 45 and then through ventilation air stream supply 50 whilst the push buttons are non-active. When a button is pressed to supply power air to inflate or elevate a bed section, the continuous ventilation air stream supply 50 is temporarily cut off and directed via the button pressed to the appropriate bed section requiring air supply. When the button is released, the bed section so inflated is automatically sealed off and the air supply is restored to the ventilation air stream 50. When the push button to deflate a bed section is pushed, air from the section is released to atmosphere until the button is released. The deflate push button does not effect the ventilation air stream flow 50. A simple air controlled bed unit is illustrated in Fig. 5 having a portable air pump unit 52 which can be connected to any of the bed inflation points as needed to adjust pressure in the pressure zones via a plug and socket type connector in the load support air supply manifold 13 and when pressure adjustments are complete the pump unit 52 is connected to the ventilation air stream supply manifold 15.
A similar system of inflation and deflation control is utilised in the seat unit illustrated in Fig. 6, the seat and back unit illustrated in Fig. 7 and the seat, back and leg unit illustrated in Fig. 8.
It will thus be seen that the force ventilated support system in accordance with the present invention enables additional assistance to be provided to a patient or user of a device incorporating such support system, the force ventilated arrangement enabling the patient or user to remain comfortable.
It is clear that the various integers of the force ventilated support system of the present invention can be formed from any suitable type of materials and modifications can be utilised in connection with the load support air supply system and the ventilation air stream system, whilst still falling within the scope of the present invention.
The embodiment illustrated in Fig. 9 shows a mattress assembly 90 having a multiple section manifold whereby groups of air sacs 91 may be controlled collectively in strata and pressure zones. In this connection, the zones are arranged in groups horizontally and vertically in strata.
In a preferred embodiment, the lowest strata level 92 would be quite firm, whereby the patient on the bed would not, under any circumstances, be able to sink through the lowest strata level which would be quite firm, whereby the patient on the bed would not, under any circumstances, be able to sink through the lowest level and thereby touch the bed base. On the other hand, the upper level pressure would be set so that the patient is allowed to sink into the upper surface 93 and suitably be suspended just above the surface of the lower level. Further adjustment could be effected to provide maximum comfort in the full confidence that the patient could never reach the bed base through the lower level.
In a preferred embodiment, the horizontal upper strata zone pressures would be set to give typical settings as follows:

Upper body Medium pressure 10-18 mm/Hg

Mid-section Higher pressure 15-22 mm/Hg

Foot section Low pressure 3-8 mm/Hg
Of course, it is to be understood that the pressures selected in the various sections of the mattress will be dependent upon patient weight and physical features.
Fig. 10 illustrates an airtight sac system in accordance with the further aspect of the present invention, but which does not require the ventilation air stream of the first aspect of the present invention.
It can thus be seen that a mattress or the like air support system can be made utilising a plurality of one or more air-tight membranes. Whilst the embodiment of Fig. 10 shows three pressure zones, 101, 102, 103, it is to be understood that any selected number of pressure zones can be provided. Moreover, as indicated above, the mattress can be made so as to be utilised with or without a forced ventilation air flow.
The embodiment illustrated in Fig. 11 indicates that independent internal pressurised devices or members 112 can be inserted into an air sac 111 and can be used, with or without internal air-tight membranes, so as to create pressure zones within pressure zones, as well as strata pressure zones. Thus, one can provide an inflatable member which is locatable in the air sac and which, in use, will act in a similar manner to the invention by providing multi-pressure zone air sacs.
Fig. 12 illustrates a section of a low air loss support system sac 120, into which has been incorporated a nominally air-proof membrane 121 which has been perforated by the provision of carefully graded holes 122, thereby allowing air to pass through the membrane at a controlled rate relative to the air losses through stitch holes in the upper half of the sac. Such holes may be replaced by an adjustable valve or pressure regulator 123 built in to the membrane or by a separate feed nozzle from the air supply 124. The arrangement of Fig. 12 makes it possible to adjust the pressure in the upper part of the sac to a lower pressure than that in the lower part of the sac. This type of control is suitable for use with twin nozzles or single nozzle low air loss support systems.
Fig. 13 diagrammatically illustrates a single pressure element bed 130, viz, in which the whole sac is at one pressure. Fig. 13 also shows the bed to be divided, along its length, in three pressure zones 131. 132, 133. Each zone comprises a group of sacs and the zones or sac groups are arranged so that different parts of the body can be supported at the optimum pressure setting to give lowest interface pressure and maximum comfort.
It can clearly be seen that if the bed had only a single continuous zone which was at one pressure throughout its length, then the pressure generated by the weight of a patient would be common throughout. In effect, this would mean that unduly high pressures would be transmitted to areas such as the heels, which would be at the same pressure as at the mid-section. Thus, for example, if a pressure of 20 mm/Hg was present under the mid-section 132, this would also apply 20 mm/Hg to the heel section 133. On the other hand, with a multi-zoned air pressure system of the invention, the pressure applied to the heel section 133 would typically be of the order of 3-8 mm/Hg.
It is to be noted that the arrangement of the horizontal pressure zones can be extremely important and can be utilised in any multiple form depending upon the special effect required.
Fig. 14 schematically illustrates a multi-pressure air support system in accordance with the further aspect of the present invention incorporated within a mattress cover 140. The upper surface of the mattress is usually water vapour permeable to prevent soiling, but will allow perspiration to pass through and to allow for surface washing. As illustrated, the interior of the mattress cover has vertical dividers 141 across the bed attached to the bottom and top sides of the mattress cover.
Again as illustrated, the inflatable sac elements 142 pass between the vertical dividers 141 and are therefore loosely held in place whilst at the same time being separated from one another. This arrangement allows the sacs to move easily but at the same time be retained in their allotted space even when the sac is less than half full of air and is accordingly quite flaccid.
The control of the semi-inflated sac elements 142 referred to above is generally to prevent the sacs from being pushed apart when a patient is restless on the bed and prevents the patient from falling between the sacs to land or bottom out on the bed frame.
It will thus be seen that the multi-pressure zone air support system in accordance with the present invention enables the pressure in an air support system to be varied along its depth and/or length. In the case of a mattress, as indicated above, it can clearly be seen that a patient can be made far more comfortable by the use of multi-pressure zone air sacs than with a bed at a constant pressure.
It is clear that the various components of the multi-pressure zone air support system of the present invention can be formed from any suitable type of materials and modifications can be utilised in connection with the manner in which the multi-pressure zone arrangement is achieved, whilst still falling within the scope of the present invention.

Claims

A zero-loss, multi-pressure, air support system comprising an air support means in the form of a mattress assembly having a first plurality of inflatable, air-tight, air sacs forming chambers (10) which are connected together in at least first and second pressure zones (11), each of said pressure zones being operated at a pre-selected pressure, a specific pressure being selected for each zone, and multi-section pressure regulation means (12) which operates to inflate said first pressure zone to a first pressure and operates to inflate said second pressure zone to a second pressure which is different from the first pressure, and further including forced air ventilation means;
characterised in that said forced air ventilation means includes a second plurality of inflatable air sacs with apertures (16) forming second chambers, an air supply pump (52), and a manifold (15), said second chambers being connected to the manifold (15), said air supply pump (52) providing a stream of air through the manifold (15) to the inflatable air sacs, and said apertures (16) providing a ventilation air stream.
An air support system as claimed in claim 1, further including a group of air-tight inflatable sacs (130) forming chambers which are connected to form three pressure zones, (131, 132, 133) a pressure being selected for said third pressure zone, and wherein the multi-section pressure regulating means (12) operates to inflate said third pressure zone to a pressure selected to be different from the first and from the second pressure.
A zero-loss air support system, as claimed in claim 1, wherein the mattress assembly comprises:

a first plurality of inflatable sacs which are completely air-tight connected together so as to form at least a first group (47) and a second group (48) of sacs, each group defining an individual pressure zone capable to operate at a different pressure; and

means (45, 46) for applying pressure to each group of sacs until each zone is inflated to a different pre-selected pressure;

and further including a second plurality of inflatable sacs (51) with apertures (16) defined therein; and

means (50) for maintaining a continuous supply of forced air, said apertures (16) providing a ventilating air stream.
A zero-loss air support system as claimed in claim 3, wherein said means for applying pressure includes a first manifold connected to apply pressure to the first group of sacs; a second manifold connected to apply pressure to the second group of sacs; and means for supplying pressure to said first and second manifolds.
A zero-loss air support system as claimed in claim 4, further including a third group of completely air-tight inflatable sacs (49) connected to form a third group defining a further pressure zone, and wherein said means (45, 46) for applying pressure includes a third manifold connected to the third group of sacs for applying pressure to said third manifold, whereby each pressure zone may be maintained at a different pre-selected pressure.
A zero-loss air support system as claimed in claims 3, 4 or 5, wherein said means for maintaining a continuous supply of forced air includes a manifold connected to said second plurality of inflatable sacs, and a source of air under pressure for maintaining the plurality of sacs inflated while the ventilating air stream is provided.
A zero-loss support system as claimed in claims 2, 3, 4, 5 or 6, wherein an inflatable sac of the first plurality of sacs and an inflatable sac of the second plurality of sacs are formed by a triple membrane arrangement, two of the membranes providing a completely air-tight chamber and a third, outer membrane having apertures, said outer membrane connected so as to form a chamber which is capable to discharge a ventilating air stream.