WO2005007054A1

WO2005007054A1 - System and method for medical equipment

Info

Publication number: WO2005007054A1
Application number: PCT/SE2004/001139
Authority: WO
Inventors: Paul Storr; Mikael Wiberg
Original assignee: Kanmed Ab
Priority date: 2003-07-17
Filing date: 2004-07-16
Publication date: 2005-01-27
Also published as: SE526612C2; SE0302093D0; SE0302093L

Abstract

The invention relates to a system for controlling pressure and temperature in a cushion intended for a body, such as a human or an animal. The system comprises a cushion made by a flexible material that is tight or is provided with a tight layer, wherein the cushion of the flexible material encloses at least one volume and is comprising at least a first connection portion and a second connection portion, which connection portions are arranged to function as inlets and/or outlets. The system also comprises a control unit that is arranged to transfer one or more pressurised, tempered mediums to the cushion alternately via the first connection portion and the second connection portion. The invention also relates to a method, a control unit and a cushion.

Description

System and method for medical equipment

Field of the invention

The present invention relates, above all, to medical and long- term care equipment, and in particular to a system for controlling pressure and temperature in a cushion according to the preamble of claim 1.

The present invention further relates to a method for controlling pressure and temperature in a cushion according to the preamble of claim 5.

The present invention further relates to a control unit according to the preamble of claim 9.

The present invention also relates to a cushion according to the preamble of claim 14.

Background of the invention

In both long-term care and medical care pressure sores/bedsores are a well known problem. Pressure sores arises when a part of the body of a patient remains lying in a position wherein the pressure from the support on the body part exceeds the capillary pressure in the skin, i.e. the blood supply in the area subjected to pressure ceases. After some time, necrosis occurs and the result often is a slow- healing bedsore which may be deep, infected and may take months to heal. The bedsore further results in great suffering for the patient.

Bedsores often appear in long-term care/elder care, wherein in particularly elderly, bony persons with a low blood pressure, paralysed persons and diabetics are particularly exposed. Also, bedsores often appear in intensive care, wherein the patient is immobile, and further during especially complicated operations, which often results in hours of rest on a hard operating-table. If the worst comes to the worst an uncomplicated operation may result in a complicated pressure sore with a long healing period.

Another problem, especially during operations, is that patients cool down. It is not unusual that a patient is freezing already prior to the entrance into the operating room, and when he then subsequently is given an anaesthetic and medicine for muscle relaxation and pain-relief, the natural defence of the body against cooling is partly set out of action. If nothing is done about this, the body temperature decreases relatively fast in an operating room which is kept at a temperature of approximately 18 - 23 degrees centigrade. This hypothermia may result in a number of negative side- effects, such as an increased risk of infections in operation wounds, increased bleeding in operated tissue, heart rhythm disorders and awakening shivers which affects heart and lungs. These side-effects result in increased costs for the medical service of the community.

The prior art reveals various attempts to solve the above mentioned problems.

DE 297 21 132 Ul discloses an air mattress, consisting of a flexible and air-tight material, through which supplied air flows. The air mattress is preferably intended for use on an operating-table to pressure relieve and warm patients, and is connected to a control apparatus via tubes that are connected to an inlet and one or more outlets of the mattress. The control apparatus comprises a compressor and a heating element to control the pressure and temperature of the air. The Swedish patent application 0201461-1 also discloses a system to control pressure and temperature in a mattress intended for use during e.g. operations. The mattress is formed by a flexible material that is provided with a tight layer and is comprising at least one inlet and one outlet. A control unit is arranged to transfer a pressurised tempered medium to the mattress via the inlet arranged in the mattress, whereupon the transferred medium is intended to flow through the mattress to thereby pressure relieve and heat a person resting on the mattress.

A problem with the above solutions, however, is that the surface temperature of the mattress becomes uneven due to the fact that the hot air provided to the mattress is cooled during the flow through the mattress, which has as result that the mattress becomes hottest where the air is let into the mattress and colder the further away the air gets from the inlet. Another problem with the above solutions is that it is not possible to transfer enough energy to warm a patient without reaching critical temperatures in the mattress.

Objects and most important features of the invention

The object of the present invention is to provide a system and a method that solves the above problem by achieving a more even temperature distribution in a cushion, through which a pressurised, tempered medium is flown. This object is achieved by a system and a method as defined in claim 1 and 5, respectively.

Another object of the present invention is to provide a control unit according to claim 9.

Another object of the present invention is to provide a cushion made by a flexible material and which is tight or provided with a tight layer and that solves the above- mentioned problem. This object is achieved by a cushion according to claim 14.

Pressure and temperature in a cushion made by a flexible material that is tight or provided with a tight layer are controlled over a control unit. The cushion encloses at least one volume and comprises a first connection portion and a second connection portion, which connection portions are arranged to function as inlets and/or outlets. The control unit is arranged to transfer one or more pressurised, tempered mediums alternately via the first connection portion and the second connection portion. This has the advantage that by alternately transferring tempered pressurised medium to the cushion via various connections, the surface temperature of the cushion may be kept very even over the surface of the cushion, i.e. a low temperature gradient is obtained. This further has the advantage that the present invention, in contrast to the prior art, is capable of transferring enough energy to the mattress to warm a patient without reaching critical temperatures, or too high temperature gradients, in the mattress .

Said mediums may be brought back to the control unit after circulating through the cushion to thereby be able to be recirculated and/or emitted to the surroundings . This has the advantage that said medium may be reheated and recirculated through the cushion in a closed system. This further has the advantage that the medium that has flown through the mattress does not increase the air circulation in the room where the cushion is situated, which in turn has the advantage that the risk of bacterial attacks, e.g. in an operating room, is reduced. Alternatively, said medium may be led via an outlet to e.g. a ventilation system. Further, the system may be arranged, in a first state, to transfer the pressurised, tempered mediums to the cushion via the first connection portion, wherein the first connection portion is functioning as an inlet and the second connection portion is functioning as an outlet, and, in a second state, to transfer pressurised, tempered mediums to the cushion via the second connection portion, wherein the first connection portion is functioning as an outlet.

The system may further be arranged to alter transfer of pressurised, tempered medium from one connection portion to the other when a time period in the interval 1 second to 60 seconds has elapsed. This has the advantage that even a relatively slow alternating speed may be used at the same time as a desired result is obtained.

The cushion may comprise several volumes/sections that may be individually controlled. This has the advantage that the pressure of the cushion may be adapted to different parts of the body, and that the body temperature may be controlled individually for different sections . Each section may be connected to a control unit via separate tubes. E.g., it may be desirable to have a higher pressure in the section onto which the hip is resting at the same time as a higher temperature may be desired in the section onto which the head is resting.

The cushion may be made in various ways. This has the advantage that the cushion may be specially adapted depending on the area of use, e.g. a cushion may be split between the legs to facilitate use during genital operations. Further, a part of the cushion may be cut off in respect of the flow of the medium to be able to be used when required, e.g. the cushion may be provided with an arm that may be rolled out and that is intended to be used during e.g. narcosis or hand operations .

The present invention may be used for both controlled warming and cooling. This has the advantage that the cushion also may be used at e.g. heart operations where a patient is kept cooled down in a controlled manner.

The cushion may also be provided with an arrangement to facilitate relocation of the cushion. This has the advantage that a patient that is resting on the cushion and is about to be moved, e.g. from a hospital bed to an operating-table, may be moved, e.g. by pulling the cushion from the bed to the table. This makes it possible to avoid heavy lifts for the personnel .

The mattress may be provided with handles at the long-sides and/or the short-sides. With the use of the handles, a patient may easily be moved from a bed to an operating-table or vice versa. The mattress with the patient may then be pulled or lifted to the operating-table from the bed via the handles.

The cushion may also be used for animals during veterinary care. This has the advantage that pressure wounds and hypothermia of animals that are injured or under treatment may be avoided.

The cushion may be made by a disposable material. This has the advantage that clinical regulations regarding e.g. an operations room easily may be fulfilled by exchanging the cushion prior to each operation.

The cushion may be designed as e.g. a mattress, a pillow, a seat cushion or a cushion to lie down on.

Brief description of the drawings The invention will now be described more in detail by means of embodiments and by reference to the accompanying drawings, in which :

Fig.l shows a preferred embodiment of the present invention.

Fig. 2a shows an embodiment of a control unit according to the present invention.

Fig. 2b shows an embodiment of a control panel of a control unit according to the present invention.

Fig. 3 shows an embodiment of a cushion according to the present invention.

Detailed description of preferred embodiments of the invention

Fig. 1 shows an embodiment of the present invention. A mattress 101 that may be resembled with an ordinary air mattress is connected to a control unit 102 via two tubes 103, 104. The tubes are connected to the mattress 101 and the control unit 102, respectively, in any suitable manner, e.g. by means of adapters. The mattress is made from a flexible material, which in itself is tight or is provided with a tightening layer. E.g., the material may consist of double- folded plastic, such as EVA plastic or PVC plastic, the edges of which being seam-welded to form an enclosed volume. Alternatively, the material may consist of a non woven material with a tightening surface layer, e.g. consisting of plastic. In this case, it is preferred that the inside of the material is coated with the tightening layer, at the same time as the outside surface of the material is constructed to be as comfortable as possible for a person resting on it. If the mattress consists of double-folded plastic, it may be provided with a cover to make the mattress more comfortable for a patient to rest upon. The thickness of the mattress in a pressurised state is preferably 3-7 cm, although it may be thicker or thinner. Further, a mattress that is intended for an adult may have the size of 80*220 cm, while a mattress intended for a small child may be of the size of 40*70 cm. Length and width, however, may of course be fully adjusted based on what is suitable for the area of use in question, and the measurements stated herein merely constitute examples of various sizes.

Air is heated in the control unit 102 and is then blown into the mattress 101 via one of the tubes 103, 104. The air blown into the mattress circulates back and forth through the mattress via the two cannels 105, 106 and subsequently leaves the mattress through the other one of the tubes 103, 104 and is led back to the control unit to again be heated by the control unit. The air circulation thus constitutes a closed loop. When a certain time has elapsed, e.g. 30 seconds, the air flow is alternated and air is instead blown into the mattress via the other one of the two tubes 103, 104.

The functional principle is described more in detail with reference to fig. 2a, which shows the control unit 102 more in detail. The control unit 102 is provided with a compressor 201 that is used to achieve a desired pressure inside the mattress and that is capable of delivering up to a certain amount of air and up to a certain pressure, e.g. up to 50 1/min and up to 100 mbar.

In a first operating mode, the pressurised air is then put into circulation by means of a first fan 202 for circulation through the mattress by supplying the air to the mattress via the first tube 103. The pressurised air is heated by a first heating element 204 to a desired temperature prior to it being blown into the mattress via the first tube 103. The circulating air flows through the mattress through the channels 105, 106, whereupon the air is brought back to the control unit via the tube 104. In the control unit, the air is heated again by means of the heating element 204 in order to again be circulated through the mattress by means of the first fan 202. When a certain time has elapsed, e.g. 30 s, the first fan 202 is stopped and immediately, or after one or a couple of seconds, the other fan 203 is started to circulate the air in the other direction instead, this time heated by the heating element 205. The function of the fans, as of the heating elements and of the compressor, is controlled by a processor 206, which is arranged in the control unit.

Two temperature sensors 207, 208 are used by the processor to sense the air temperature of air coming into and going out from the mattress. The measured air temperatures are then used to adjust the operation of the heating elements 204, 205. By measuring the mean value of air incoming to and outgoing from the mattress, a direct value of the temperature in the mattress is directly obtained. This has the advantage that the temperature of the air in the mattress may be calculated in a simple manner, irrespective of the length of the tubes. The temperature sensors may also be used by the processor to detect abnormal temperature rises and/or temperature drops. A pressure sensor 210 is also connected to the processor for sensing the pressure in the mattress, and for detecting abnormal pressure increases/decreases.

The control unit may also be provided with an electrical pressure relief valve 209 that functions as an overload protection by opening if the pressure in the system exceeds a certain pressure. The sensors 207, 208 may also be connected to the mattress 101. It is also possible to arrange a sensor on a patient so as to allow the temperature of the patient to be directly readable on the control unit. The control unit is also provided with a control panel 211, which is described more in detail with reference to fig. 2b.

The control unit may also be provided with an output 230 for connection to a remote control 231. Via the remote control 231, a conscious patient may set a desired pressure and temperature by himself via buttons 232-235 (shown in fig. 2b) . The remote control may be either wire connected or wireless. The remote control may also be provided with a display to show set/measured values. The control unit may also be provided with a data output, e.g. an RS232 output 240, to allow control of the control unit from an external computer 241 or an external system. The data output may also be used to collect, by means of an external computer 241 or an external system, data such as date/time, temperature and pressure, e.g. once

/s, once /min or more seldom. The control unit should also be provided with a high-temperature protection to limit the maximum temperature of the mattress, e.g. 42°C. In order to avoid disturbances in the form of noise, especially from the compressor, the interior of the control unit may be surrounded by a sound-absorbing material. Also, the tube between mattress and control unit may be provided with some sort of sound insulation to reduce disturbances from flowing air.

The control unit may also be provided with an overheating protection in the form of two capillary thermostats that are coupled in series with the heating elements 204, 205. The capillary thermostats acts as an extra system that shuts off the heating elements at a certain preset temperature irrespective of if the electronics attempts to keep the heating elements activated. This has the advantage that overheating of the mattress can not occur if the electronics would stop operating. By providing the capillary thermostats with a certain preset hysteresis during manufacturing, these may also keep the system operating by successively activating and deactivating the heating elements at the maximum and minimum values of the hysteresis. The hysteresis should be arranged such that the resulting temperature in the mattress is kept at a desired temperature.

In fig. 2b is shown an example on how a control panel 211 on the control unit may be designed. The pressure is controlled by buttons to increase pressure 212 and decrease pressure 213. Correspondingly, the temperature is controlled by buttons to increase temperature 214 and to decrease temperature 215. Alternatively, rotary buttons may be used to set pressure and temperature. Another alternative is to use a touch sensitive display instead of buttons. Set values of pressure and temperature and instantaneous values of the pressure and temperature are shown on a display 216. As an alternative to the pressure, the weight of the patient may be shown. There are also indicators 218, 219 on the control panel in form of e.g. lights to make an alarm in form of flashing signals when an alarm event occurs. Also, alarms in form of sound signals may be used. Further, the control unit may be provided with an emergency evacuation button 220, which when pressed activates immediate for fast emptying of the mattress. This is particularly suitable at occasions when a patient suffers a cardiac arrest and a hard support is needed in order to perform an efficient heart-lung rescue.

In fig. 3 is shown a preferred embodiment of a mattress 301 according to the present invention. The mattress 301 has two connections 302, 303, operating as inlets and outlets and are intended for connection to a control unit according to the above description. The mattress is further provided with four channels 304-307, of which two 304, 307 extends along the outer edges of the mattress and only has openings closest to the inlets/outlets. The channels 305, 306 extends along the entire mattress and are connected at the end of the mattress facing away from the inlets/outlets so as to allow air to flow through the mattress from one connection to the other. The channels 304, 307, which only have openings closest to the inlets/outlets and thereby do not constitute subjects to any heating, have the function of isolating the warm part of the mattress, the channels 305-306, which results in a higher energy emission towards the patient. Further, the isolating channels 304, 307 have the effect that they isolate the warm part of the mattress from personnel standing next to the mattress, so as to ascertain that the personnel do not have to suffer from heat transfer from the mattress. The upper side and bottom side of the mattress are further joined together, e.g. by welding, to achieve turbulence in the air flow, which results in an even better heat transfer towards a person resting on the mattress. The mattress may, however, also be designed without these joints. In fig. 3 is also shown an example on how the tubes may be connected to the mattress. In this example, the mattress is made by double-folded EVA plastic or PVC plastic, which have been cut such that two protruding portions 309, 310 are formed. The protruding portions are then welded together at the edges so as to form two connection sleeves. The tubes are then introduced into the connection sleeves whereupon e.g. a rubber strap 311, 312 is used to tighten around the tubes to prevent leakage. This embodiment is thus of very simple construction and is thus also inexpensive to manufacture. An alternative way of connecting the tubes is to do this by means of a bayonet coupling provided with a non return valve so that the mattress may be disconnected from the control unit without the air contained in the mattress leaking. In this way, a mattress may be moved from one control unit to another, e.g. during a part of an operation or when moving from one operating room to a recovery ward, with a retained pressure.

The mattress according to the present invention may be put on top of an operating table. When a patient that is to be operated rests on the mattress 101, the pressure and temperature may be set on the control unit 102 such that the patient is resting comfortable to avoid arising of bed sores, at the same time as the patient is warmed by the mattress to avoid hypothermia and complications associated therewith. Further, since the patient rests warmly and comfortably, the mattress makes it easier for the patient to relax, which in turn makes anaesthesizeing of the patient easier. The patient may rest on the mattress during the whole operation and also during the awakening so that the patient rests comfortably even then. Since the patient rests comfortable during the operation and the awakening, the risk of the patient getting a backache after the operation reduces.

In an alternative embodiment, the mattress is embodied as a half-body mattress. This may be used to heat the upper part of the body of a patient during e.g. genital operations where the patient is resting with the legs held high, or during other operations or occasions when it is not suitable with a whole- body mattress. The mattress may also be embodied as a seat cushion for use where a patient is sitting during the operation .

^" In the above description air has been used as circulating medium. However, e.g. nitrogen may be used, or a combination of various mediums . The control unit may be provided with a connection for allowing connection of a medium from an external source. The closed system described in the above description is intended to be a system that is substantially air tight. It is, however, considered to be embraced that a certain air leakage, e.g. 250 1/hour, may exist at the mattress and/or the tubes and/or the control unit. Thus, a certain amount of air shall be provided to the system as needed.

In the above description the function has been described in the case of warming a patient. The invention, however, may also be used for controlled cooling of a patient during e.g. heart operations, where it is important to keep the patient at a constant, low temperature. Instead of heating the air, the air is cooled in the control unit and thus cold air instead of hot air is circulated through the mattress. The cooling in the control unit may carried out by means of a refrigeration compressor, a Peltier element or an ice container. The control unit may also be arranged to heat the patient when the operation is completed.

The present invention is also suitable for use in e.g. wards for long-term patients, where patients often are confined to bed. The mattress is as well suitable for use at intensive care units where the patients often are confined to bed, and at emergency wards and radiotherapy department where patients often are cold. The mattress may also be used in e.g. rescue helicopters to calm and warm shocked and cooled survivors. The mattress is further suitable for use in home nursing.

The invention is also suitable for use in veterinary care to avoid pressure wounds and cooling of animals that are injured or under treatment.

Where applicable, e.g. for long-term patients, the control unit may arranged to vary in particular the pressure in the mattress according to a preset program to thus further reduce the risk of bedsores.

Claims

1. System for controlling pressure and temperature in a cushion intended for a body, such as a human or an animal, comprising: a cushion made from a flexible material that is tight or is provided with a tight layer, wherein the cushion of the flexible material encloses at least one volume and comprises at least a first connection portion and a second connection portion, which connection portions are arranged to function as inlets and/or outlets, and a control unit, arranged to transfer pressurised, tempered gas to the cushion via an inlet arranged in the cushion, where transferred gas is intended to flow through the cushion, characterised in that the control unit is arranged to transfer pressurised tempered gas alternately via the first connection portion and the second connection portion, so that gas transferred via the first connection portion circulates through the cushion in an opposite direction as compared to gas transferred via the second connection portion, whereupon the gas circulates through the cushion in interconnected channels .

2. System according to claim 1, characterised in that said gas is brought back to the control unit after circulating through the cushion to thereby be able to be recirculated and/or emitted to the surroundings.

3. System according to claim 1 or 2, characterised in that the system is arranged - in a first state, to transfer pressurised, tempered gas to the cushion via the first connection portion, whereby the first connection portion is functioning as an inlet and the second connection portion is functioning as an outlet, and - in a second state, to transfer pressurised, tempered gas to the cushion via the second connection portion, whereby the first connection portion is functioning as an outlet .

4. System according to any of the claims 1-3, characterised in that the system is arranged to alter transfer of pressurised, tempered gas from one connection portion to the other when a time period in the interval 1 second to 60 seconds has elapsed.

5. Method for controlling pressure and temperature in a cushion intended for a body, such as a human or an animal, comprising: - to a cushion, made by a flexible material that is tight or is provided with a tight layer, where the cushion of the flexible material encloses at least one volume and is comprising at least a first connection portion and a second connection portion, which connection portions are arranged to function as inlets and/or outlets, transferring one or more pressurised, tempered gases to the cushion via an -inlet arranged in the cushion, where transferred gases are intended to flow through the cushion, wherein the method further comprises the step: - of transferring pressurised tempered gas to the cushion alternating via the first connection portion and the second connection portion, wherein gas that is transferred via the first connection portion flows through the cushion in a direction substantially opposite as compared to gas that is transferred via the second connection portion, wherein the gas circulates in channels that are interconnected.

6. Method according to claim 5, characterised in that said gas is brought back to the control unit after circulating through the cushion to thereby be able to be recirculated and/or emitted to the surroundings .

7. Method according to claim 5 or 6, characterised in - that in a first step pressurised, tempered gas is transferred to the cushion via the first connection portion, whereby the first connection portion is functioning as an inlet and the second connection portion is functioning as an outlet, and - that in a second step pressurised, tempered gas is transferred to the cushion via the second connection portion, whereby the first connection portion is functioning as an outlet.

8. Method according to any of the claims 5-7, characterised in that the method alters transfer of pressurised, tempered gas from one connection portion to the other when a time period in the interval 1 second to 60 seconds has elapsed.

9. Control unit intended for connection to a cushion consisting of a flexible material, characterised in that the control unit comprises : means for heating or cooling at least one pressurised gas, and means for transferring said pressurised heated or cooled gas to the cushion alternatively via first and second connection portions arranged on the cushion.

10. Control unit according to claim 9, characterised in that the control unit further comprises means for pressurising said gas.

11. Control unit according to claim 9 or 10, characterised in that the control unit further comprises means for receiving gas that has flown through the cushion to recirculate it and/or emit it to the surroundings. -

12. Control unit according to any of the claims 9-11, characterised in that the control unit is arranged - in a first state, to transfer pressurised, tempered gas to the cushion via the first connection portion, whereby the first connection portion is functioning as an inlet and the second connection portion is functioning as an outlet, and - in a second state, to transfer pressurised, tempered gas to the cushion via the second connection portion, whereby the first connection portion is functioning as an outlet.

13. Control unit according to any of the claims 9-12, characterised in that the control unit is arranged to alter transfer of pressurised, tempered gas from one connection portion to the other when a time period in the interval 1 second to 60 seconds has elapsed.

14. Cushion made by a flexible material that is tight or provided with a tight layer, where the cushion of the flexible material encloses at least one volume and is comprising at least a first connection portion and a second connection portion, which connection portions are arranged to function as inlets and/or outlets, characterised in that the upper side and the lower side in the enclosed volume are joined together at a plurality of spots or areas, e.g. by welding, to achieve turbulence in the enclosed volume when pressurised tempered mediums are flown through the volume.

15. Cushion according to claim 14, characterised in that the first connection portion and the second connection portion are connected to each other via channels that are extending forward and backward through substantially the entire length or width of the cushion.

16. Cushion according to claim 15, characterised in that the cushion further comprises, on respective sides of the forward and backward extending channels, at least one channel that extends through substantially the entire length or width or the cushion.

17. Cushion according to claim 16, characterised in that the respective channels on each side of the forward and backward extending channels comprises only one opening.

18. Cushion according to any of the claims 14-17, characterised in that said first connection portion and second connection portion consist of pipes or tubes with different dimensions positioned in each other.

19. Cushion according to any of the claims 14-18, characterised in that the flow of medium through a portion of the enclosed volume can be cut off or opened as desired.

20. Cushion according to any of the claims 14-19, characterised in that the thickness of the cushion in pressurised state is 2-20 cm, and preferably 3-10 cm.

21. Cushion according to any of the claims 14-20, characterised in that the width of the cushion in pressurised state is 20-200 cm, and the length is 30-250 cm.

22. Cushion according to any of the claims 14-21, characterised in that said medium is air.

23. Cushion according to any of the claims 14-22, characterised in that the tight material is EVA plastic or PVC plastic.