Moisture Control System
20170354557 · 2017-12-14
Inventors
- John H. Vrzalik (San Antonio, TX, US)
- Mathew Pickering (San Antonio, TX, US)
- Kz Hong (San Antonio, TX, US)
Cpc classification
A61G7/05784
HUMAN NECESSITIES
International classification
A61G7/057
HUMAN NECESSITIES
Abstract
A moisture control system includes a moisture control coverlet (10) and a fluid pump (18). The moisture control coverlet (10) includes a fluid pathway therein for moisture removal fluid. The fluid pump (18) is coupled to the fluid pathway for pumping fluid out of the fluid pathway by negative pressure at a fluid pump rate. The fluid pump rate can be adjustable and/or can be greater than 1 CFM.
Claims
1. A moisture control system, comprising: a moisture control coverlet including a fluid pathway therein for moisture removal fluid; and a fluid pump coupled to the fluid pathway for pumping fluid out of the fluid pathway by negative pressure at a fluid pump rate, wherein the fluid pump rate is adjustable.
2. The moisture control system according to claim 1, further comprising at least one flow restriction member configured to selectively restrict a flow of fluid pumped by the fluid pump to adjust the fluid pump rate.
3. The moisture control system according to claim 2, wherein the at least one flow restriction member is a plurality of flow restriction members each individually configure to selectively restrict the flow of fluid pumped by the fluid pump.
4. The moisture control system according to claim 2, wherein the at least one flow restriction member includes an adjustable cover for an exhaust opening or vent on the fluid pump.
5. The moisture control system according to claim 1, wherein the fluid pump rate is at least 1 CFM.
6. The moisture control system according to claim 1, wherein the fluid pump rate is at least 6 CFM.
7. The moisture control system according to claim 1, wherein the fluid pump rate is at least 10 CFM.
8. The moisture control system according to claim 1, further comprising a variable power supply operable to supply power to the fluid pump.
9. The moisture control system according to claim 8, wherein the power supply is configured to supply power at a plurality of different power levels.
10. The moisture control system according to claim 1, further comprising a control unit operable to adjust the fluid pump rate.
11. The moisture control system according to claim 10, further comprising a sensor for sensing a condition at a treatment zone, the sensor being configured to sense one or more of temperature and humidity; wherein the control unit is operable to adjust the fluid pump rate in response to a condition sensed by the sensor.
12. A method of moisture control, comprising: operating a fluid pump of a moisture control coverlet to pump fluid out of a fluid pathway in the moisture control coverlet by negative pressure at a first fluid pump rate; operating the fluid pump to pump fluid out of the fluid pathway by negative pressure at a second fluid pump rate; in response to a reduction in one or more of temperature and humidity at a treatment zone, wherein the second fluid pump rate is less than the first fluid pump rate.
13. The method according to claim 12, further comprising varying a pump rate of the fluid pump to provide a controlled temperature reduction at the treatment zone.
14. The method according to claim 12, wherein the operation of the fluid pump to pump fluid out of the fluid pathway by negative pressure at the second fluid pump rate includes configuring at least one flow restriction member to restrict a flow of the fluid pumped by the fluid pump.
15. The method according to claim 12, wherein the operation of the fluid pump to pump fluid out of the fluid pathway by negative pressure at the second fluid pump rate includes adjusting a power supplied to the fluid pump.
16. The method of claim 12, further comprising operating the fluid pump at the first pump rate when a patient position on the coverlet is: perspiring, has a skin relatively humidity of about 100% and/or liquid is present at the treatment zone.
17. The method of claim 16, wherein the first fluid pump rate is about 12 CFM to about 25 CFM to achieve a MVTR of at least about 450 gm/m.sup.2/hr.
18. The method of claim 12, further comprising operating the fluid pump at the second pump rate when a patient position on the coverlet is: not perspiring, has a skin relatively humidity of less than about 100% and/or no liquid is present at the treatment zone.
19. The method of claim 18, wherein the second pump rate is less than about 1 CFM.
20. A method of moisture control, comprising: operating a fluid pump of a moisture control coverlet to pump fluid out of a fluid pathway in the moisture control coverlet by negative pressure; regulating the pump rate in response to a determination as to a resistance to heat transfer of a patient's skin.
Description
[0046] Embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying drawings, in which:
[0047]
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DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0059]
[0060] The moisture control system 100 includes a coverlet 10 and fluid pump 18. The fluid pump 18 is in this embodiment coupled to the coverlet 10 by a flexible conduit such as a tube 20. However, in other embodiments, the fluid pump 18 can be mounted directly onto the coverlet 10.
[0061] In this embodiment, the fluid pump is an air pump for pumping air.
[0062] In this embodiment, the coverlet includes three layers, a first layer 30, second layer 28 and third layer 24. The first layer 30 is vapour permeable, liquid impermeable, and either air permeable or impermeable. The second layer 25 is sandwiched between and separates the first and third layers and is a spacer material that allows air to flow through it under negative pressure. A spacer material can be any material that includes a volume of air within the material and allows air to move through the material. The third layer 24 comprises a material that is vapour impermeable, air impermeable and liquid impermeable.
[0063] The first layer and third layer are connected at a permeable interface 26 that is highly air permeable to allow air flow created by the fluid pump 18 to cause air flow into the second layer 28 through the permeable interface 26 essentially unrestricted as shown by the arrow 32.
[0064] Permeable interface 26 exists only at an end 34 of the coverlet 10 opposite an end 36 where the fluid pump 18 is coupled to the coverlet 10. At the end 36, the first and third layers are joined together and an aperture 38 is provided in the first and/or third layers by which the fluid pump 18 is coupled to the second layer 28. In this embodiment, this is by the conduit 20 being coupled to the aperture 38.
[0065] Along sides of the coverlet 10 between the ends 34 and 36, and the first and third layers are joined together in a non-permeable manner.
[0066] In this way, a fluid pathway is provided by the permeable interface 26, the second layer 28 and the aperture 38 so that air can flow into the permeable interface 26, through second layer 28, and out via the fluid pump 18 as shown by arrow 40. In embodiments in which the first layer is air permeable, the fluid pathway can also include the first layer as air can flow into the second layer through the first layer.
[0067] The system 100 is placed on a support surface 42, typically a mattress of a bed, although it can be a chair or other support surface. The system is arranged on the support surface 42 so that the third layer 24 is adjacent to the support surface 42.
[0068] The system 100 is designed for a patient to lie or sit in a treatment zone 44 which is adjacent to the first layer 30.
[0069] The fluid pump 18 includes a power supply 46. The power supply is variable so as to be operable to supply power to the fluid pump 18 at any one of a plurality of power levels. The power supply for example includes a power selection element for selecting a level of power supply.
[0070] In addition, the fluid pump 18 includes a plurality of flow restriction members configurable to selectively restrict the flow of air pumped through the system 100. In this embodiment, the flow restriction members are vent covers as described with respect to
[0071]
[0072] The system includes covers 50 which can be placed at least partly over each vent 48 to obstruct air flow through the vent. Although
[0073] Each vent 48 has associated with it a coupling member 52 which is operable to cooperate with a corresponding coupling member 54 on the associated cover 50 arranged so that when the coupling member 52 cooperates with a corresponding coupling member 54 on the associated cover 50, that associated cover 50 at least partially covers the vent 48. The coupling members 54 on the covers 50 can be releasably coupled to respective coupling members 52 on the fluid pump 18.
[0074] When a cover is coupled to the fluid pump 18, the cover 50 will typically completely cover the corresponding vent 48 whereby to obstruct air being expelled via that vent 48 and thereby restrict the flow of air through the system 100. However, it is not excluded that the cover 50 can cover only part of the associated vent 48.
[0075] The covers 50 can be coupled to the fluid pump 18 so as to cover the vents 48 in a plurality of combinations. Each different combination affects the fluid flow through the system to a different degree, and results in the system providing a different amount of cooling to the treatment zone 44.
[0076] The vents in
TABLE-US-00001 Fan Air Restriction Skin T, ° C. All vents open 36.12 Vents 1 & 3 closed 36.32 Vent 3 closed 36.46 Vents 2 & 3 closed 36.50 All vents closed 36.52 Fan off 36.54
[0077] Although the depicted embodiment includes a pump with a fan and vents, other forms of pump can be used, and these other pumps may include other forms of exhaust outputs. Furthermore, the flow restriction members do not need in all embodiments to be in the fluid pump 18. They can be provided in the fluid pathway in the coverlet 10 for example. However, in all embodiments, there is at least one flow restriction member which can be selectively configured to restrict the flow of fluid pumped by the fluid pump.
[0078]
[0079] The sensor 58 is in signal communication with the control unit 56 and is configured to provide readings, in this case of temperature, to the control unit 56.
[0080] It is to be noted that although the control unit 56 is in this embodiment in the fluid pump, this is not necessary in all embodiments. It can be a separate device or incorporated in a separate device, such as a computer. However, the control unit 56 is configured to control the operation of the fluid pump 18′. It is to be appreciated that the functionality of the control unit may be incorporated as code (such as a software algorithm or program) residing in firmware and/or on computer useable medium having control logic for enabling execution on a computer system having a computer processor. Such a computer system typically includes memory storage configured to provide output from execution of the code which configures a processor in accordance with the execution. The code can be arranged as firmware or software, and can be organized as a set of modules such as discrete code modules, function calls, procedure calls or objects in an object-oriented programming environment. If implemented using modules, the code can comprise a single module or a plurality of modules that operate in cooperation with one another.
[0081] The control unit 56 is operable to control the power supplied to the fluid pump 18′. In addition, in this embodiment, the covers are attached to the fluid pump 18′ and are movable by the control unit between an open configuration in which they do not cover their associated vent so their associated vent is open, and a closed configuration in which they cover their associated vent. In some embodiments, the covers are also movable into intermediate positions in which they partially cover their associated vent.
[0082] The covers can be coupled to the fluid pump by a hinged member, which hinged member can be moved by a motor which is controlled by the control unit 56.
[0083] The control unit 56 is configured to vary the power supplied to the fluid pump 18′ and/or to vary the flow restrictions provided by the covers in response to readings received from the sensor 58. In this way, the control unit 56 can provide a controlled temperature reduction to the treatment zone 44.
[0084] In one embodiment, the control unit 56 is programmed with one or a plurality of thresholds and is configured to provide a predetermined power to the pump 18′ and/or a predetermined configuration of the covers in dependence on the temperature measured by the sensor 58, with respect to the one or more thresholds. For example, the control unit 56 can be configured to reduce the power supplied to the pump 18′ and/or increase the flow restriction provided by the covers 50 in response to the temperature as measured by the sensor 58 falling below a threshold.
[0085] In the embodiment of
[0086] An operator, such as a nurse or other practitioner, operates the fluid pump 18 at an appropriate level depending on the amount of liquid or moisture present in the treatment zone. An appropriate pumping rate can be selected by appropriate selection of the power supplied to the fluid pump 18 by the power supply 46 and/or by appropriate closing and/or opening of vents 48 of fluid pump 18.
[0087] Advantageously, the fluid pump can be operated to pump fluid using negative pressure air flow at a pump rate of at least 1 CFM, more preferably at least 10 CFM and even more preferably at least 20 CFM but can also be adjusted to provide a pump rate of less than 1 CFM by operation of the power supply and/or configuration of the covers as described below.
[0088] When pumped at a high pump rate, the air velocity in the fluid pathway of the system is significantly increased. Furthermore, by using negative pressure air flow, the coverlet is prevented from ballooning or blowing up in response to the increased air flow, which would otherwise prevent the increase in air velocity. This is illustrated in
[0089] Liquid at the treatment zone evaporates and vapour from the liquid or moisture at the treatment zone 44 diffuses through the first layer 30 into the second layer 28. However, this will primarily occur when the relative humidity of the air in the second layer 28 is less than the relative humidity of the air in the treatment zone 44. However, as the fluid pump 18 is operated, the air in the second layer 28 is pumped out through the fluid pathway and out of the fluid pump 18 in the direction of the arrow 40 taking vapour with it, and it is replaced with new air through the interface 26 in the direction of arrow 32, and/or through the first layer 30 in embodiments in which the first layer 30 is air permeable. This movement of air keeps the relative humidity in the second layer 28 low, allowing the evaporation of the liquid and the diffusion of vapour through the first layer 30 to continue.
[0090] An advantage of embodiments of the present disclosure is that because of the high pump rate of the fluid pump 18 the air in the second layer 28 has a high velocity and can dry, or evaporate, significant quantities of liquid from the treatment zone 44, such as that resulting from liquid incontinence. The high air velocity enabled by the high pump rate and the use of negative pressure fluid flow enables moisture to be quickly carried away from the treatment zone in the form of vapour by the air flow, maximising moisture vapour transfer rate from a patient in the treatment zone.
[0091]
[0092] The temperature sensors 59 are configured to maintain the sweating hot plate temperature at a predetermined temperature, in this case 35 degrees C. The temperatures sensors 59 are built into sweating hot plate device. When cooling is caused by evaporation, conduction, and/or convection, the sensors 59 detect a reduction in temperature (below 35° C.), and increase heat supply 64 to maintain 35 C. at sweating hot plate.
[0093] When testing, a dry test (towel 62 is tested dry) is performed first to measure heat loss by conduction and convection. Then a “wet” test is performed with towel 62 completely saturated to ensure 100% relative humidity.
[0094] In the dry test, the heat 64 required to maintain sensors 59 at constant 35° C. is heat loss from convection and conduction. In the wet test, heat 64 required to maintain sensors 59 at 35° C. is a combination of conduction, convection, and evaporative (latent heat of evaporation).
[0095] In the dry test, heat 64 is provided by the sweating hot plate. In the second layer 28, air 68 is drawn by the pumping of fluid pump 18 out of the system 100. This removes, by conduction and convection, temperature from the sweating hot plate and this change of temperature is detected by the temperature sensors 59.
[0096] In the wet test, when heat 64 is provided by the sweating hot plate, moisture in the wet towel 62 is evaporated and diffuses through the first layer 30 as shown by the arrows 66. This vapour passes into the second layer 28. In the second layer 28, air 68 drawn by the pumping of fluid pump 18 draws the vapour out of the second layer 28 as shown by the arrows 70 and out of the system 100. This removes, in particular by way of the latent heat of evaporation, but also by conduction and convection, temperature from the sweating hot plate and this change of temperature is detected by the temperature sensors 59.
[0097] The difference in heat in the wet and dry tests is the heat losses due to evaporation. This heat difference is used to calculate grams of water evaporated over the area of the sweating hot plate. With that, moisture vapor transfer rate, MVTR, is calculated in grams of water evaporated per sq. meter per hour.
[0098] This test is much better than the Reger method. The Reger method starts with a wet towel and no more water is added for the duration of the test. In a high MVTR system, the Reger towel can dry completely, so RH drops drastically during the test, giving false, low MVTR for the best support systems. In contrast, in the sweating hot plate method, the interface between hot plate and support surface is continuously flooded with water to ensure it remains at 100% RH. Vapor transmission (evaporation) remains at maximum for the duration of the test, regardless of the evaporation, or vapor transmission rate of the support surface being tested.
[0099] An example illustrating the efficacy of embodiments of the present disclosure is shown in
[0100] It is shown by this that the system is effective at removing significant volumes of liquid from the treatment zone 44 in a relatively limited amount of time. Indeed, the rate of liquid removal in the test shown in
[0101] In general, the fluid pump 18 is operated at a high pump rate above 1 CFM, 10 CFM or 20 CFM as mentioned above, while there is liquid present in the treatment zone 44. This high pump rate provides a high moisture vapour transfer rate (MVTR) through a high evaporation and diffusion rate of liquid from the treatment zone 44 into the second layer 28 and a high velocity of air removing vapour from the second layer 28. This high evaporation rate causes cooling of the patient, which can cause the patient to be cool or cold. In response to the patient feeling cool or cold, the operator is able to adjust the pump rate of the fluid pump 18 to reduce the pump rate, and thereby reduce the cooling effect of the system.
[0102] In general, temperature reduction is a desirable feature during the time that liquid or moisture is being removed. Accordingly, the fluid pump 18 is generally operated at a high rate of above 1 CFM, 6 CFM or 20 CFM while a patient is perspiring, and has a skin relative humidity of 100%, or there is other liquid at the treatment zone 44.
[0103] However, when perspiration stops, in other words when the skin relative humidity has dropped below 100%, and all other liquid has been removed from the treatment zone 44, evaporative cooling tapers off and almost stops. However, there is additional cooling from conduction and convection resulting in heat transferring from the patient at the treatment zone 44 through the first layer 30 and into the second layer 28 where it is carried away by the airflow. While cooling as a result of conductive and convective heat loss is considerably less than evaporative cooling, if the patient begins to feel uncomfortably cool, the rate of pumping can be reduced, to below 1 CFM for example, to reduce the air velocity and thereby reduce the temperature cooling rate. In some embodiments a sensor 58 as described above can be provided in the embodiment of
[0104]
[0105]
[0106] A heat flux between two points at temperatures T.sub.1 and T.sub.2 respectively can be determined by (T.sub.1-T.sub.2)/R where R is the resistance between the two points.
[0107] In
[0108] Typically, the skin core temperature will be about 37° C. (98.6° F.), the ambient temperature will be about 25° C. (77° F.) and the skin resistance to heat transfer will be about 0.05 m.sup.2 °K/W.
[0109] As can be seen from the equation above, if R.sub.system is increased, for example when the skin becomes dry without sweating and evaporation therefore decreases, and/or the air flow rate through the system decreases, the skin surface temperature will increase.
[0110] In the embodiment of
[0111] It is not necessary in all embodiments for both the power supply 56 and the flow restriction members to be configured to change the fluid pump rate of the fluid pump 18. In embodiments, only one or other of these features may be configurable in order to change the fluid pump rate. Furthermore, instead of, or in addition to, changing the power level of the power supply, the power supply can be repeatedly switched on and off to provide a desired fluid pump rate.
[0112] In some embodiments, a disposable chuck 80 can be placed in the treatment zone 44 such as shown in
[0113] As shown in
[0114]
[0115] Disposable chuck 80 and reusable chuck 80′ are used to absorb, not evaporate, liquid, and collect solid incontinence. Either a disposable chuck 80 or a reusable chuck 80′ can be used with coverlet 10 to absorb much of the liquid incontinence, but frequently, some of the liquid spills onto the support surface. With the use of coverlet 10 according to an embodiment of the present disclosure, the coverlet can remove this excess liquid incontinence much more rapidly than it could remove all the liquid incontinence if the chuck 80 or 80′ were not used. But, the chuck should be removed from the sleep surface system, along with the liquid incontinence it has absorbed, to dry the treatment zone 44 more rapidly than if only coverlet 10 or chuck were used were used alone. The use of either chuck essentially stops the vapor transmission capability of the coverlet 10 from the area directly under the chuck, since the chuck is liquid and vapor impermeable. Therefore, the chuck should be removed after the liquid incontinence event for the coverlet to be most effective. With proper caregiver attention, the combined use of chuck 80 or 80′ and coverlet 10 dries the treatment zone more rapidly than if either coverlet or chuck is used alone. However, if the chuck is not removed, the moisture vapor removal capability of the coverlet is compromised since the chuck cannot allow evaporation of liquid through its bottom layer, which is liquid and vapor impermeable.
[0116] The coverlet does not need exactly three layers. Other arrangements are possible. For example, possible configurations of the fluid pathway are provided in U.S. Pat. Nos. 8,372,182 and 8,918,930, the entirety of which are incorporated herein by reference herein. Details and modifications described therein are applicable to the coverlet described herein. However, other modifications may also be made to the configuration of the coverlet, provided the coverlet includes a fluid pathway through which the pump system can pump moisture removal fluid to remove moisture from the vicinity of a patient adjacent to the coverlet.
[0117] All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention(s) taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.
[0118] The foregoing description has been presented for the purpose of illustration and description only and is not to be construed as limiting the scope of the invention in any way. The scope of the invention is to be determined from the claims appended hereto. While devices, kits, systems and methods have been described with reference to certain embodiments within this disclosure, one of ordinary skill in the art will recognize that additions, deletions, substitutions and improvements can be made while remaining within the scope and spirit of the invention as defined by the appended claims.