U.S. patent application number 12/937306 was filed with the patent office on 2011-02-03 for microclimate management system.
This patent application is currently assigned to HILL-ROM SERVICES, INC.. Invention is credited to Stephen L. Douglas, Stephen C. Flint, Charles A. Lachenbruch, Rachel Williamson.
Application Number | 20110024076 12/937306 |
Document ID | / |
Family ID | 41050399 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024076 |
Kind Code |
A1 |
Lachenbruch; Charles A. ; et
al. |
February 3, 2011 |
MICROCLIMATE MANAGEMENT SYSTEM
Abstract
A microclimate management system (10) comprises a mattress (16),
a topper (18), and a control system (14). The topper (18) is
coupled to the mattress (16) and is supported thereon. The topper
(18) defines an interior region (42) and a person contacting
surface (52). The control system (14) is configured to maintain at
least one of a surface temperature, a relative surface humidity,
and a heat withdrawal capacity of at least a portion of the person
contacting surface (52) within a predetermined operating
Inventors: |
Lachenbruch; Charles A.;
(Lakeway, TX) ; Douglas; Stephen L.; (Batesville,
IN) ; Flint; Stephen C.; (Fortville, IN) ;
Williamson; Rachel; (Batesville, IN) |
Correspondence
Address: |
HILL-ROM SERVICES, INC.
Legal Dept., Mail Code K04, 1069 State Road 46 East
BATESVILLE
IN
47006
US
|
Assignee: |
HILL-ROM SERVICES, INC.
Wilmington
DE
|
Family ID: |
41050399 |
Appl. No.: |
12/937306 |
Filed: |
April 15, 2009 |
PCT Filed: |
April 15, 2009 |
PCT NO: |
PCT/US2009/040661 |
371 Date: |
October 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61045111 |
Apr 15, 2008 |
|
|
|
Current U.S.
Class: |
165/11.1 ;
165/222; 165/48.1 |
Current CPC
Class: |
A61G 2210/70 20130101;
A61G 2210/90 20130101; A61F 2007/0086 20130101; A61G 7/05784
20161101; A61F 2007/0056 20130101; A61G 7/057 20130101; A61F 7/0053
20130101 |
Class at
Publication: |
165/11.1 ;
165/222; 165/48.1 |
International
Class: |
F28D 21/00 20060101
F28D021/00; F24F 3/14 20060101 F24F003/14; F24D 19/00 20060101
F24D019/00 |
Claims
1. A microclimate management system comprising: a support device
including a person contacting surface; a fluid supply coupled with
the support device and supplying fluid to the support device; and a
controller operatively coupled to the fluid supply and including an
instruction set, the instruction set causing the controller to
regulate at least one of the rate the fluid is supplied by the
fluid supply and temperature of the fluid supplied by the fluid
supply to maintain a heat withdrawal capacity of at least a portion
of the person contacting surface below about 140 W/m.sup.2.
2. The microclimate management system of claim 1, wherein the heat
withdrawal capacity of at least a portion of the person contacting
surface is maintained above about 50 W/m.sup.2.
3. The microclimate management system of claim 1, wherein the heat
withdrawal capacity of at least a portion of the person contacting
surface is maintained between about 60 W/m.sup.2 and about 125
W/m.sup.2.
4. The microclimate management system of claim 1, wherein the
temperature of the person contacting surface is maintained below
about 35.8.degree. C. (96.5.degree. F.).
5. The microclimate management system of claim 1, wherein the
temperature of the person contacting surface is maintained above
about 31.1.degree. C. (88.degree. F.).
6. The microclimate management system of claim 1, wherein the
temperature of the person contacting surface is maintained between
about 32.2.degree. C. (90.degree. F.) and about 35.3.degree. C.
(95.5.degree. F.).
7. The microclimate management system of claim 1, wherein the
relative humidity of the person contacting surface is maintained
below about 95%.
8. The microclimate management system of claim 1, wherein the
relative humidity of the person contacting surface is maintained
above about 20%.
9. The microclimate management system of claim 1, wherein the
relative humidity of the person contacting surface is maintained
between about 55% and about 90%.
10. The microclimate management system of claim 1 further
comprising sensors operatively coupled to the controller, the
sensors being configured to provide a signal indicative of one of
the temperature and humidity of the person contacting surface.
11. The microclimate management system of claim 10, wherein support
device includes a cover defining an interior region and a portion
of the cover defining the person contacting surface, the sensors
being integrated into the cover.
12. The microclimate management system of claim 10, wherein the
sensors are positioned within the interior region proximate the
person contacting surface.
13. The microclimate management system of claim 1, wherein the
support device includes at least one fluid bladder therein, the
controller being configured to regulate the pressure of the fluid
within the fluid bladder.
14. The microclimate management system of claim 1, wherein the
fluid supply includes at least one of a heating element and a
cooling element.
15. The microclimate management system of claim 1, wherein the
support device includes a mattress and a topper coupled on the
mattress, the topper includes a cover defining an interior region
and a portion of the cover defining the person contacting
surface.
16. The microclimate management system of claim 15, wherein the
topper includes a support layer positioned within the interior
region.
17. The microclimate management system of claim 16, wherein the
support layer is a three-dimensionally engineered spacer.
18. The microclimate management system of claim 1 further
comprising an input device configured to receive an input from a
person indicative of a person's comfort level.
19. The microclimate management system of claim 18, wherein the
instruction set causes the controller to further regulate the fluid
supply as a function of the input from the input device.
20. The microclimate management system of claim 1, wherein the heat
withdrawal capacity of at least a portion of the person contacting
surface is maintained below about 140 W/m.sup.2 for less than about
6 hours.
21. The microclimate management system of claim 1, wherein the heat
withdrawal capacity of at least a portion of the person contacting
surface is maintained below about 140 W/m.sup.2 for more than about
6 hours.
22-197. (canceled)
198. A method of manufacturing a microclimate management system,
comprising: providing a support device in communication with a
fluid supply, the support device including: a cover defining an
interior region and at least a portion of the cover defining a
person contacting surface, the cover also defining a fluid
permeability parameter, a thermal conductivity parameter, and a
thickness parameter, and a spacer positioned within the interior
region, the spacer defining a fluid resistance parameter, a fluid
permeability parameter, a thermal conductivity parameter, and a
thickness parameter; and varying at least one of the fluid
permeability parameter of the cover, the thickness parameter of the
cover, the thermal conductivity of the cover, the fluid resistance
parameter of the spacer, the fluid permeability parameter of the
spacer, the thermal conductivity parameter of the spacer, and the
thickness parameter of the spacer to cooperate with the fluid
supply to maintain a heat withdrawal capacity of at least a portion
of the person contacting surface below about 140 W/m.sup.2.
199-229. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 61/045,111 titled MICROCLIMATE MANAGEMENT
SYSTEM filed on Apr. 15, 2008, the contents of which are
incorporated herein by reference.
BACKGROUND
[0002] This disclosure relates to microclimate management systems,
and more particularly, but not exclusively to microclimate
management systems adapted to maintain the temperature and/or
relative humidity of a patient contacting surface of a support
device within a predetermined range in some exemplary
embodiments.
[0003] Patients lying on support devices, such as hospital bed
mattresses, for extended periods of time are susceptible to the
development of pressure ulcers (also known as decubitus ulcers or
bedsores). Pressure ulcers are lesions often found adjacent bony or
cartilaginous areas. Pressure ulcers may be caused by tissue
forces, such as, for example, pressure, i.e., compression of
tissues, shear force, and friction. Pressure ulcer formation may be
exacerbated by the presence of excess body heat and/or
moisture.
[0004] While various microclimate management systems have been
developed, in certain applications there is still room for
improvement. Thus, a need persists for further contributions in
this area of technology.
SUMMARY
[0005] One illustrative embodiment, a microclimate management
system including a support device, a fluid supply, and a controller
having an instruction set that causes the controller to regulate
the rate and temperature of fluid supplied by the fluid supply to
maintain a heat withdrawal capacity of a least a portion of the
person contacting surface below about 140 W/m.sup.2. In another
illustrative embodiment, a microclimate management system can
include a mattress, a topper supported on the mattress, and a
control system configured to maintain at least one of the surface
temperature, humidity, and heat withdrawal capacity of at least a
portion of the person contacting surface within a predetermined
range. In yet another illustrative embodiment, a microclimate
management system including a support device, a fluid supply, and a
controller having an instruction set that causes the controller to
regulate the rate and temperature of fluid supplied by the fluid
supply to maintain a surface temperature of at least a portion of
the person contacting surface above 88.degree. F. and a relative
humidity of at least a portion of the person contacting surface
below about 95%. In still another illustrative embodiment, a fluid
supply in communication with a topper is regulated as a function of
at least one of the temperature and the relative humidity of at
least a portion of the person contacting surface to maintain at
least a portion of the person contacting surface within a
predetermined operating range. In a further illustrative
embodiment, a fluid supply in communication with a support device
is regulated as a function of at least two of the temperature and
the relative humidity of at least a portion of the person
contacting surface and a user input to maintain at least a portion
of the person contacting surface within a predetermined operating
range. In yet a further illustrative embodiment, a fluid supply in
communication with a topper is regulated as a function of at least
one of the temperature and the relative humidity of at least a
portion of the person contacting surface, and a user input to
maintain at least a portion of the person contacting surface within
a predetermined operating range. In still a further illustrative
embodiment, at least one of a rate and a temperature of a fluid
supplied by a fluid supply to a support device is regulated as a
function of the temperature and relative humidity of the person
contacting surface to maintain the person contacting surface within
a predetermined operating range. In another illustrative
embodiment, an apparatus includes a mattress, a topper, and a
sensor configured to sense at least one of a temperature or a
person contacting surface, a relative humidity of a person
contacting surface, a temperature of the fluid within the topper,
and a relative humidity of the fluid within the topper. In yet
another illustrative embodiment, a fluid supply is selected to
cooperate with at least one of the fluid permeability parameter of
the cover, the thickness parameter of the cover, the thermal
conductivity of the cover, the fluid resistance parameter of the
spacer, the fluid permeability parameter of the spacer, the thermal
conductivity parameter of the spacer, and the thickness parameter
of the spacer to maintain a heat withdrawal capacity of at least a
portion of the person contacting surface below about 140 W/m.sup.2.
In still another embodiment, at least one of the fluid permeability
parameter of the cover, the thickness parameter of the cover, the
thermal conductivity of the cover, the fluid resistance parameter
of the spacer, the fluid permeability parameter of the spacer, the
thermal conductivity parameter of the spacer, and the thickness
parameter of the spacer is varied to cooperate with the fluid
supply to maintain a heat withdrawal capacity of at least a portion
of the person contacting surface below about 140 W/m.sup.2.
[0006] Further embodiments of this disclosure will become apparent
from the following description and accompanying drawings included
herewithin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a graph illustrating the relationship between the
pressure exerted on the skin and the amount of time the pressure is
exerted before damage to the skin occurs for a given skin
temperature.
[0008] FIG. 2 is a graph illustrating some principles of the
present invention.
[0009] FIG. 3 is a perspective view of a microclimate management
system according to one embodiment of the current disclosure
including a support device and a control system.
[0010] FIG. 4 is a partial sectional view of the embodiment of FIG.
3 illustrating the controller and sensors positioned within a cover
of the support device.
[0011] FIG. 5 is a cross-sectional side view of the illustrative
support device of FIG. 3 including a low air-loss topper positioned
on top of the upper mattress surface of the mattress.
[0012] FIG. 6 is a graph illustrating the relationship between the
composition of the support device of FIG. 3 and the temperature of
the skin contacting the support device over time, according to some
principles of the present invention.
[0013] FIG. 7 is a partial cross-sectional side view of the
illustrative support device of FIG. 3 taken along line 5-5 with a
person resting thereon illustrating the flow of air, heat, and
moisture through the support device.
[0014] FIG. 8 is a cross-sectional side view of a support device
taken along line 5-5 of FIG. 3 according to another embodiment of
the current disclosure including a low air-loss topper with
bladders or a mattress with bladders.
[0015] FIG. 9 is a cross-sectional side view of a support taken
along line 5-5 of FIG. 3 according to another embodiment of the
current disclosure including a low air-loss topper positioned
within the mattress cover mattress.
DESCRIPTION OF SPECIFIC ILLUSTRATIVE EMBODIMENTS
[0016] While the system present in this disclosure can take many
different forms, for the purpose of promoting an understanding of
the disclosure, reference will now be made to the embodiments
illustrated in the drawings, and specific language will be used to
describe the same. No limitation of the scope of the disclosure is
thereby intended. Alterations, further modifications of the
described embodiments, and any further applications of the
principles of the disclosure as described herein as would normally
occur to one skilled in the art to which the disclosure relates are
contemplated.
[0017] One illustrative embodiment, a microclimate management
system including a support device, a fluid supply, and a controller
having an instruction set that causes the controller to regulate
the rate and temperature of fluid supplied by the fluid supply to
maintain a heat withdrawal capacity of a least a portion of the
person contacting surface below about 140 W/m.sup.2. In another
illustrative embodiment, a microclimate management system can
include a mattress, a topper supported on the mattress, and a
control system configured to maintain at least one of the surface
temperature, humidity, and heat withdrawal capacity of at least a
portion of the person contacting surface within a predetermined
range. In yet another illustrative embodiment, a microclimate
management system including a support device, a fluid supply, and a
controller having an instruction set that causes the controller to
regulate the rate and temperature of fluid supplied by the fluid
supply to maintain a surface temperature of at least a portion of
the person contacting surface above 88.degree. F. and a relative
humidity of at least a portion of the person contacting surface
below about 95%. In still another illustrative embodiment, a fluid
supply in communication with a topper is regulated as a function of
at least one of the temperature and the relative humidity of at
least a portion of the person contacting surface to maintain at
least a portion of the person contacting surface within a
predetermined operating range. In a further illustrative
embodiment, a fluid supply in communication with a support device
is regulated as a function of at least two of the temperature and
the relative humidity of at least a portion of the person
contacting surface and a user input to maintain at least a portion
of the person contacting surface within a predetermined operating
range. In yet a further illustrative embodiment, a fluid supply in
communication with a topper is regulated as a function of at least
one of the temperature and the relative humidity of at least a
portion of the person contacting surface, and a user input to
maintain at least a portion of the person contacting surface within
a predetermined operating range. In still a further illustrative
embodiment, at least one of a rate and a temperature of a fluid
supplied by a fluid supply to a support device is regulated as a
function of the temperature and relative humidity of the person
contacting surface to maintain the person contacting surface within
a predetermined operating range. In another illustrative
embodiment, an apparatus includes a mattress, a topper, and a
sensor configured to sense at least one of a temperature or a
person contacting surface, a relative humidity of a person
contacting surface, a temperature of the fluid within the topper,
and a relative humidity of the fluid within the topper. In yet
another illustrative embodiment, a fluid supply is selected to
cooperate with at least one of the fluid permeability parameter of
the cover, the thickness parameter of the cover, the thermal
conductivity of the cover, the fluid resistance parameter of the
spacer, the fluid permeability parameter of the spacer, the thermal
conductivity parameter of the spacer, and the thickness parameter
of the spacer to maintain a heat withdrawal capacity of at least a
portion of the person contacting surface below about 140 W/m.sup.2.
In still another embodiment, at least one of the fluid permeability
parameter of the cover, the thickness parameter of the cover, the
thermal conductivity of the cover, the fluid resistance parameter
of the spacer, the fluid permeability parameter of the spacer, the
thermal conductivity parameter of the spacer, and the thickness
parameter of the spacer is varied to cooperate with the fluid
supply to maintain a heat withdrawal capacity of at least a portion
of the person contacting surface below about 140 W/m.sup.2
[0018] A microclimate management system 10, described in more
detail in connection with FIG. 3, can manage the temperature of a
person's skin. Limiting skin warming can be accomplished by cooling
the skin, which can reduces the metabolic demand of the tissue so
that the tissue can withstand an exerted pressure for a longer
period without breaking down, as shown in FIG. 1. Cooling the skin
to the point of excessive patient discomfort or hypothermia is
preferably avoided.
[0019] A microclimate management system 10 can also manage the
accumulation of moisture against a person's skin. By limiting skin
warming and moisture accumulation, ischemia, which is a restriction
in blood supply generally due to factors in the blood vessels with
resultant damage or dysfunction of tissue, and maceration, which is
the softening and weakening of the skin that occurs when its
collagen linkages are dissolved over time, can be reduced.
Furthermore, limiting moisture accumulation can help decrease the
coefficient of friction between the wet skin and common bedding
materials, thereby reducing the forces imposed on the weakened skin
for any sliding movement.
[0020] Skin temperature can influence the perspiration rate or
sweat rate of the skin, metabolic demand of the skin, and person's
level of comfort, as shown in FIG. 2, in which the x-axis
corresponds to the temperature of the skin increasing from left to
right (in degrees Fahrenheit) and the y-axis corresponds to scaled
units representing the various dependent variables depicted. Curve
S1, the sweat curve, illustrates the rate at which sweat is
produced by the skin as the skin temperature varies. The sweat rate
of the skin at a given location can be affected by the core
temperature of the person, the person's mean skin temperature, and
the local skin temperature. The sweat rate for a given patch of
skin can increase as the patch of skin is warmed. The skin sweat
rate can remain relatively constant at temperatures below a sweat
threshold ST1 of approximately 35.3.degree. C. (95.5.degree. F.).
The sweat rate below this threshold can be between about 5
g/m.sup.2-hr to 10 g/m.sup.2-hr. As the skin temperature increases
beyond the sweat threshold the sweat rate can begin to rise
dramatically.
[0021] Curve MR1, shown in FIG. 2, illustrates the extent to which
the metabolic demand of the skin varies with the skin temperature.
As the temperature of the skin increases, the demand for additional
blood to be supplied to the skin can increases and the affected
blood vessels can dilate to accommodate the demand. However, when
high pressures are applied to the skin, dilation of the blood
vessels can be impeded and nutrients may not be supplied to the
skin at the necessary rate. This could result in a nutrient deficit
leading to ischemic necrosis.
[0022] Comfort curve C1 illustrates the level of patient comfort
experienced while resting on the microclimate management system 10
as a function of the skin temperature. While a patient's comfort
level is not an exact measurement and can differ from person to
person for any given temperature, the comfort curve is generally
representative of the comfort level for the majority of patients
observed. Variations in the level of comfort can be due to factors
including, but not limited to, the person's body mass index, age,
physical conditioning, personal preferences, and injury or
illness.
[0023] Analysis of the sweat curve S1, metabolic rate curve MR1,
and comfort curve C1, as shown in FIG. 2, demonstrates a range of
skin temperatures among which the risk of pressure ulcers can be
decreased. Specifically, a person's skin can be maintained in one
embodiment at a temperature below approximately 35.8.degree. C.
(96.5.degree. F.), a temperature at which comfort begins to
noticeably decline, as shown by curve C1 in FIG. 2. More
specifically, a person's skin can be maintained at a temperature
below approximately 35.3.degree. C. (95.5.degree. F.), a
temperature at which the sweat threshold ST1 is reached. Still more
specifically, a person's skin can be maintained within a
temperature range of about 32.2.degree. C. (90.degree. F.) and
35.3.degree. C. (95.5.degree. F.). In other embodiments, the
temperature of the skin can be maintained between about
31.1.degree. C. (88.degree. F.) and 35.8.degree. C. (96.5.degree.
F.). It should be appreciated that the temperature of the skin can
be maintained below 32.2.degree. C. (90.degree. F.); however, the
risk of causing the person resting on the microclimate management
system 10 to go into hypothermia increases as the temperature of
the patient the skin decreases. It should also be appreciated that
the temperature of the skin can be maintained above 35.8.degree. C.
(96.5.degree. F.); however, the risk of increasing the occurrences
of pressure ulcers increases as the temperature of the skin
increases.
[0024] The temperature of the skin can be maintained within the
previously stated ranges for a minimum of 6 hours. More
specifically, the temperature of the skin can be maintained within
the previously stated temperature ranges for 12 hours or more.
Still more specifically, the temperature of the skin can be
maintained within the previously stated temperature ranges for 24
hours or more. In other embodiments the temperature of the skin can
be maintained for less than 6 hours. It should be appreciated that
other parameters, such as relative humidity and heat transfer rate,
can be maintained within their respective ranges for the previously
stated amounts of time.
[0025] The temperature of the skin of a person on the microclimate
management system 10 can depend upon the heat withdrawn from their
skin. The total heat withdrawal capacity (THW capacity) parameter
is the cooling power of the surface in Watts/m.sup.2 with higher
values indicating greater heat transfer. The THW capacity depends
upon both the heat withdrawn due to dry flux and that removed due
to wet flux.
[0026] The dry flux measures the ability of a surface, such as the
patient contacting surface 52 of the support apparatus 12 shown in
FIG. 3, to remove heat from the person's skin in the absence of
moisture on the skin. The dry flux remains constant regardless of
how much the skin is sweating.
[0027] The wet flux represents the heat removed from the skin due
to evaporation and is proportional to the evaporative capacity of a
surface, such as the patient contacting surface 52 of the support
apparatus 12 shown in FIG. 3, interfacing with the skin. The
evaporative capacity measures a surface's ability to keep the skin
relatively dry and is a measure of the surface's ability to promote
evaporation. The parameter is measured in g/m.sup.2-hr with higher
values again indicating better performance.
[0028] To maintain the skin of a typical person engaging a patient
support 12, as shown in FIG. 3, between about 32.2.degree. C.
(90.degree. F.) and about 35.3.degree. C. (95.5.degree. F.), the
support device 12 and material (not shown) positioned between the
person and the support device 12 can have a THW capacity of between
about 60 W/m.sup.2 and 125 W/m.sup.2. In other embodiments, the TWH
capacity can be maintained between about 50 W/m.sup.2 and 140
W/m.sup.2. It should be appreciated that the THW capacity can be
maintained below 60 W/m.sup.2; however, the risk of increasing
occurrences of pressure ulcers increases as the THW capacity
increases. It should also be appreciated that the THW capacity can
be maintained above 125 W/m.sup.2; however, the risk of causing the
person to go into hypothermia increases as the THW capacity
decreases.
[0029] The relative humidity of the skin of a person on the
microclimate management system 10 can depend upon the heat removed
from their skin due to evaporation. To maintain the skin of a
typical person engaging a patient support 12 shown in FIG. 3
between about 32.2.degree. C. (90.degree. F.) and 35.degree. C.
(95.degree. F.), the support device 12 can have a relative humidity
("RH") between about 55% RH and 90% RH. In other embodiments, the
relative humidity range can be maintained between about 20% RH and
about 95% RH. It should be appreciated that the relative humidity
can be maintained below 55% RH; however, the risk of drying the
skin excessively and dehydrating the person increases as the
relative humidity decreases. It should also be appreciated that the
relative humidity can be maintained above 90% RH; however, the risk
of saturating the skin and increasing the occurrences of pressure
ulcers increases as the relative humidity increases.
[0030] The microclimate management system 10, according to one
embodiment of the current disclosure, can be configured to maintain
the skin about the aforementioned ranges as shown in FIGS. 3-5. The
microclimate management system 10 can include a support device 12
and a control system 14 adapted to manage the microclimate of the
support device 12. The microclimate management system 10 can
generally be used in the hospital setting on a hospital bed (not
shown), stretcher (not shown), or other support structure to
prevent the occurrences of pressure ulcers. It should be
appreciated that the microclimate management system 10 can be used
in any situation where a support device 12 is commonly used. The
microclimate management system 10 can prevent the occurrences of
pressure ulcers by reducing the accumulation of heat and moisture
that tends to occur on a person's skin when the person is laid on
the support device 12 in the supine position.
[0031] Some of the types of support devices 12 utilized within the
hospital setting today are: foam support devices and low air-loss
support devices. The difference in skin temperature over time as
the skin remains in contact with the foam support devices is
illustrated by curve AA, and difference in skin temperature over
time as the skin remains in contact with the low air-loss support
devices is illustrated by curve BB, as shown in FIG. 6. Foam
support devices 12 can block the natural, basal level of heat and
moisture produced by the skin that would normally flow into the
atmosphere, whereas low air-loss support devices 12 can be adapted
to remove accumulated heat and moisture. Blocking the heat and
moisture produced warms and wets the skin over time, creating an
environment that can differ markedly from the environment in which
the skin was designed to operate.
[0032] Low air-loss broadly refers to a feature of a support
surface that provides a flow of air to assist in managing the heat
and humidity (microclimate) of the skin. Two types of mechanisms
that low air-loss support devices 12 typically use to remove
accumulated moisture and heat: convective evaporation and diffusive
evaporation. Convective evaporation evaporates accumulated moisture
by blowing air on the skin. Diffusive evaporation evaporates
accumulated moisture through and under the surface of the support
device 12 to cool the skin without blowing air directly thereon. An
example of a diffusive device can be seen in FIG. 7 where the
air-loss support device 12 according to one embodiment of the
current disclosure where the patient P1 is lying on the support
device 12 in the supine position with fluid F1 flowing through the
support device 12 to remove heat H1 and moisture M1 radiated by the
patient P1. It should be appreciated that in some low air-loss
support devices 12 a combination of diffusive and convective
evaporation can be utilized.
[0033] In one illustrative embodiment, the support device 12 can
include a mattress 16 and a topper 18 as shown in FIG. 3. The
topper 18 can be positioned on top of the mattress 16 and can be
removably coupled to the mattress 16 by a plurality of fasteners
(not shown), such as, buttons, snaps, Velcro.RTM., ties, pins,
zippers, or other known fasteners, to prevent movement of the
topper 18 with respect to the mattress 16. It should be appreciated
that the topper 18 can be integrally incorporated in the mattress
16 or can be configured to mimic the structure of the mattress 16
as shown in FIGS. 8 & 9.
[0034] The mattress 16 can include an outer mattress cover 20 or
mattress ticking 20 that can define a mattress chamber 22. The
mattress ticking 20 can have a lower mattress surface 24 that can
interface with the hospital bed (not shown), and an upper mattress
surface 26 that can interface with the LAL topper 18. The mattress
chamber 22 can contain a plurality of air mattress bladders 28 and
a mattress spacer 30 therein. It should be appreciated that the
mattress 18 can contain only one mattress bladder 28 within the
mattress chamber 22. It should also be appreciated that the
mattress 18 can be composed of a polymeric material, such as, foam,
or a combination of polymeric material and bladders. The mattress
bladders 28 can be alternately inflated and deflated to create a
form of alternating pressure therapy. The bladders 28 can also be
in communication with one another such that the fluid pressure in
the bladders 28 can be maintained as pressure exerted on the
bladders 28. In other embodiments, the bladders 28 can include
holes HO therein that allow for fluid therein to be communicated
from the bladders 28 into the mattress chamber 22 as shown in FIG.
8. In still other embodiments, the bladders 28 can include other
components, such as, bladders 28, for assisting with the turning of
a patient, for assisting with lateral rotation of a patient, or
other therapy or support bladders 28.
[0035] In one illustrative embodiment, the LAL topper 18 can be a
low air-loss topper 18 (LAL topper 18) that can include an outer
LAL cover 40 or LAL ticking 40 that can define a LAL chamber 42, an
inlet 44, a vent 46, and a three-dimensionally engineered spacer
48. The LAL ticking 40 can include a lower LAL surface 50 and an
upper LAL surface 52 or patient contacting surface 52. The lower
LAL surface 50 can interface with the upper mattress surface 28.
The patient contacting surface 52 can interface with a patient P1
lying thereon as shown in FIG. 7. It should be appreciated that the
patient P1 can be separated from the patient contacting surface 52
by material (not shown), such as bedding, clothing, or other such
garments or materials, that has a total thermal conductivity of
anywhere from about 0.02 W/m-K to 1000 W/m-K. The lower LAL surface
50 and the patient contacting surface 52 can be generally shaped to
cooperate with the upper mattress surface 26 and can be secured to
one another along their respective edges by ultrasonic welding in
order to form a fluid-tight seal. It should be appreciated that the
lower LAL surface 50 and the patient contacting surface 52 can be
secured to one another by adhesive, plastic welding, or other
securing means, and can be secured along various portions of the
lower LAL surface 50 and the patient contacting surface 52.
[0036] The LAL ticking 40 of this illustrative embodiment can be
moisture permeable and air impermeable. It should be appreciated
that the LAL ticking 40 can be both moisture permeable and air
permeable. It should also be appreciated that the mattress ticking
20 and the LAL ticking 40 can be composed of the same material and
have the same physical characteristics. The moisture vapor transfer
rate for the LAL ticking 40, when fluid is being supplied to the
LAL topper 18 at a rate of 2.2 ft.sup.3/min., can be at least about
20 g/m.sup.2-hr in order to accommodate basal skin moisture
production. The moisture vapor transfer rate of the LAL ticking 40
can be 80 g/m.sup.2-hr or more. It should be appreciated that the
moisture vapor transfer rate can be between 25 g/m.sup.2-hr and 200
g/m.sup.2-hr. It should be appreciated that the moisture vapor
transfer rate can be less than about 20 g/m.sup.2-hr; however, the
amount of moisture accumulation on the skin can increase with time
and can increase the risk of maceration.
[0037] The inlet 44 can be positioned along a side of the LAL
topper 18 and can allow for fluid to be communicated from the
control system 14 into the LAL chamber 42. The inlet 44 can include
an inlet coupler 54 that can couple the control system 14 to the
LAL topper 18. It should be appreciated that the inlet coupler 54
can be secured to the LAL topper 18 such that there is a fluid
tight seal between the inlet coupler 54 and the LAL topper 18.
[0038] The vent 46 or outlet 46 can be positioned along a side of
the LAL topper 18 opposite the inlet 44. The vent 46 can be an
opening in the lower LAL surface 50 that can allow fluid entering
the inlet 44 and passing through the LAL chamber 42 to exit the LAL
topper 18. It should be appreciated that the vent 46 can be a
portion of the edges of the lower LAL surface 50 and the patient
contacting surface 52 that were not secured to one another. It
should also be appreciated that the vent 46 can be secured to the
lower LAL surface 50 or the patient contacting surface 52 opposite
the inlet 44.
[0039] The three-dimensionally engineered spacer 48 can be
positioned within the LAL chamber 42 and can separate the lower LAL
surface 50 from the patient contacting surface 52. The
three-dimensionally engineered spacer 48 can be composed of
SpaceNet.RTM., which is a product of Freudenberg. It should be
appreciated that the three-dimensionally engineered spacer 48 can
be composed of other materials having a high fluid porosity and
having some resistance against flattening. It should also be
appreciated that the three-dimensionally engineered spacer 42 can
include at least one chamber and/or bladder (not shown)
therewithin. It should also be appreciated that the mattress spacer
30 and the three-dimensionally engineered spacer 48 can be composed
of the same material and have the same physical
characteristics.
[0040] The resistance to flow for the three-dimensionally
engineered spacer 48 when fluid is supplied to the LAL topper 18 at
a rate of 2.2 ft.sup.3/min. can be less than about 1
(lb/in.sup.2)/(ft.sup.3/min.). In one illustrative embodiment, the
resistance to flow for the three-dimensionally engineered spacer 48
can be between about 0.1 (lbs./in.sup.2)/(ft.sup.3/min.) and 0.7
(lbs./in.sup.2)/(ft.sup.3/min.). It should be appreciated that the
resistance to flow can be more than 1
(lb/in.sup.2)/(ft.sup.3/min.). It should be appreciated that the
moisture vapor transfer rate can be between 25 g/m.sup.2-hr and 200
g/m.sup.2-hr. Where three-dimensionally engineered spacer 48 is
composed of SpaceNet.RTM., the thickness of the three-dimensionally
engineered spacer 48 can be between about 0.1 in. and 0.75 in. It
should be appreciated that the thickness of the three-dimensionally
engineered spacer 48 can be greater than 0.75 in.
[0041] The control system 14 can include a plurality of sensors 60,
a fluid supply 62, and a controller 64 as shown in FIGS. 3 & 4.
The sensors 60 can be temperature sensors and/or moisture sensors
that can be adapted to generate signals corresponding to the
temperature and relative humidity of the patient contacting surface
52. The sensors 60 can be positioned within the LAL ticking 40 and
can be operatively coupled with the controller 64 via a wire 66. It
should be appreciated that the sensors 60 can be coupled to the
patient contacting surface 52 or coupled within the LAL chamber 42.
It should also be appreciated that the sensors 60 can communicate
wirelessly with the controller 64.
[0042] The fluid supply 62 can be an air blower 62 that can supply
air to the LAL topper 18. It should be appreciated that the fluid
supply 62 can supply a various other gasses and/or liquids. The
fluid supply 62 can removably couple with the LAL topper 18 via a
hose 68. It should be appreciated that the fluid supply 62 can
connect directly to the LAL topper 18. It should also be
appreciated that the blower can be integrated or partially
integrated within the mattress 16 or LAL topper 18. The fluid
supply 62 may also include a heating element (not shown) and/or
cooling element (not shown) that can heat and/or cool the fluid
being supplied.
[0043] Determining what characteristics the fluid supply 62 can
have in order to meet the desired range(s) can depend on the
physical characteristics of the materials included in the support
device 12, as well as any material (not shown) positioned between
the patient P1 and the support device 12. The fluid supply can be
configured to supply fluid to the LAL topper 18 at a rate of 2.2
ft.sup.3/min. and at a temperature of about 18.3.degree. C.
(65.degree. F.) to 29.4.degree. C. (85.degree. F.) so that the
temperature of the fluid flowing directly beneath the LAL ticking
40 portion proximate the sacrum is about 29.4.degree. C.
(85.degree. F.) to 35.degree. C. (95.degree. F.). It should be
appreciated that the fluid supply 62 can supply fluid at a rate of
2.2 ft.sup.3/min. and at a temperature of about 18.3.degree. C.
(65.degree. F.) to 29.4.degree. C. (85.degree. F.) to the mattress
16. It should further be appreciated that the fluid supply 62 can
supply fluid at a temperature of about -3.9.degree. C. (25.degree.
F.) to 29.4.degree. C. (85.degree. F.). It should also be
appreciated that the fluid supply 62 can be required to supply
fluid at a rate higher or lower than 2.2 ft.sup.3/min. and/or at a
temperature lower than the aforementioned range based on the
physical characteristics of the materials included in the support
device 12 and positioned between the patient P1 and the support
device 12.
[0044] The controller 64 can be operatively coupled to the fluid
supply 62 and the sensors 60, and can be positioned within the LAL
chamber 42 of the LAL topper 18 as shown in FIGS. 3 & 4. It
should be appreciated that the controller 64 may be mounted to the
mattress 16, a hospital be frame (not shown), a footboard (not
shown), the fluid supply 62, or other support structures. It should
also be appreciated that the controller 64 can be integrated into
the fluid supply 62, a hospital bed control system (not shown), or
other control systems configured to regulate the fluid supply
62.
[0045] The controller 64 can include a processor 70 and memory 72
electrically coupled to the processor 70. The processor 70 can
process the signals received from the sensors 60 and can execute
instructions stored in the memory 72. The instructions can cause
the controller 64 to regulate operation of the fluid supply 62 in
accordance with the signals from the sensors 60 in order to
maintain the temperature and/or relative humidity of the patient
contacting surface 52 about the aforementioned ranges. The
controller 64 can also receive a user input signal from a user
input device (not shown) that allows the patient P1 to influence
the regulation of the fluid supply 62. It should be appreciated
that the user input signal can only influence the regulation of the
fluid supply 62 within the aforementioned temperature and/or
relative humidity ranges.
[0046] In operation, the fluid supply 62 can be initiated and fluid
can be supplied through the hose 66 to the inlet 44 of the LAL
topper 18. The fluid can flow into the LAL chamber 42, through the
three-dimensionally engineered spacer 48, and out the vent 46. As
the fluid flows through the LAL topper 18, the temperature and
relative humidity of the patient contacting surface 52 can be
maintained within the predetermined temperature and relative
humidity ranges, such as, the ranges described earlier. The sensors
60 can generate signals representative of the temperature and
relative humidity of the patient contact surface 52 and communicate
the signals to the processor 70 of the controller 64. The processor
70 can process the signals and can execute the instructions stored
in the memory 72 in accordance with the signals from the sensors 60
to regulate operation of the fluid supply 62 in accordance with the
signals. It should be appreciated that a patient P1 need not be
contacting the support device 12 for regulation of the temperature
and relative humidity of the patient contacting surface 52 to
occur.
[0047] Many other embodiments of the present disclosure are also
envisioned. The structure of such embodiments may utilize one or
more illustrative components described above, or other appropriate
components, now know to be developed
[0048] For example, a microclimate management system 10 comprises a
support device 12, a fluid supply 62, and a controller 64. The
support device 12 includes a person contacting surface 52. The
fluid supply 62 couples with the support device 12 and supplies
fluid to the support device 12. The controller 64 is operatively
coupled to the fluid supply 62 and includes an instruction set. The
instruction set causes the controller 64 to regulate at least one
of the rate the fluid is supplied by the fluid supply 62 and
temperature of the fluid supplied by the fluid supply 62 to
maintain a heat withdrawal capacity of at least a portion of the
person contacting surface 52 below about 140 W/m.sup.2.
[0049] In another example, a microclimate management system 10
comprises a mattress 16, a topper 18, and a control system 14. The
topper 18 is coupled to the mattress 16 and is supported thereon.
The topper 18 defines an interior region 42 and a person contacting
surface 52. The control system 14 is configured to maintain at
least one of a surface temperature, a relative surface humidity,
and a heat withdrawal capacity of at least a portion of the person
contacting surface 52 within a predetermined operating range.
[0050] In another example, a microclimate management system 10
comprises a support device 12, a fluid supply 62, and a controller
64. The support device 12 includes a person contacting surface 52.
The fluid supply 62 is coupled with the support device 12 and
supplies fluid to the support device 12. The controller 64 includes
an instruction set. The instruction set causes the controller 64 to
regulate at least one of the rate the fluid is supplied by the
fluid supply 62 and temperature of the fluid supplied by the fluid
supply 62 to maintain a surface temperature of at least a portion
of the person contacting surface 52 above about 88.degree.
Fahrenheit and a relative humidity of at least a portion of the
person contacting surface 52 below about 95%.
[0051] In yet another example, at least one of a relative humidity
and a temperature of at least a portion of a person contacting
surface 52 of a topper 18 coupled on a mattress 16 is sensed. A
fluid supply 62 in communication with the topper 18 is regulated as
a function of at least one of the temperature of at least a portion
of the person contacting surface 52 and the relative humidity of at
least a portion of the person contacting surface 52 to maintain at
least a portion of the person contacting surface 52 within a
predetermined operating range.
[0052] In yet another example, at least one of a relative humidity
and a temperature of at least a portion of a person contacting
surface 52 of a support device 12 is sensed. A person comfort input
signal is received from an input device 60. A a fluid supply 62 in
communication with the support device 12 is regulated as a function
of at least two of the temperature of at least a portion of the
person contacting surface 52, the relative humidity of at least a
portion of the person contacting surface 52, and the person comfort
input signal to maintain at least a portion of the person
contacting surface 52 within a predetermined operating range.
[0053] In still another example, at least one of a relative
humidity and a temperature of at least a portion of a person
contacting surface 52 of a topper 18 coupled on a mattress 16 is
sensed. A person comfort input signal is received from an input
device 60. A fluid supply 62 in communication with the topper 18 is
regulated as a function of at least one of the temperature of at
least a portion of the person contacting surface 52, the relative
humidity of at least a portion of the person contacting surface 52,
and the person comfort input signal to maintain at least a portion
of the person contacting surface 52 within a predetermined
operating range.
[0054] In still another example, a relative humidity and a
temperature of a person contacting surface 52 of a support device
12 is sensed. At least one of a rate and a temperature of fluid
supplied by a fluid supply 62 to the support device 12 is regulated
as a function of the temperature of the person contacting surface
52 and the relative humidity of the person contacting surface 52 to
maintain the person contacting surface 52 within a predetermined
operating range.
[0055] In a further example, an apparatus comprises a mattress 16,
a topper 18, and a sensor 60. The topper 18 is coupled on the
mattress 16. The topper 18 includes a cover 40 and has fluid
communicated through at least a portion of the topper 18. The
topper 18 defines an interior region 42 and a portion of the cover
40 defines a person contacting surface 52. The sensor 60 is
configured to sense at least one of a temperature of the person
contacting surface 52 a relative humidity of the person contacting
surface 52, a temperature of the fluid within the topper 18, and a
relative humidity of the fluid within the topper 18.
[0056] In a further example, a support device 12 is provided. The
support device 12 includes a cover 40 and a spacer 48. The cover 40
defines an interior region 42 and at least a portion of the cover
40 defines a person contacting surface 52. The cover 40 also
defines a fluid permeability parameter, a thermal conductivity
parameter, and a thickness parameter. The spacer 48 is positioned
within the interior region 42. The spacer 48 defines a fluid
resistance parameter, a fluid permeability parameter, a thermal
conductivity parameter, and a thickness parameter. A fluid supply
62 is selected to cooperate with at least one of the fluid
permeability parameter of the cover 40, the thickness parameter of
the cover 40, the thermal conductivity of the cover 40, the fluid
resistance parameter of the spacer 48, the fluid permeability
parameter of the spacer 48, the thermal conductivity parameter of
the spacer 48, and the thickness parameter of the spacer 48 to
maintain a heat withdrawal capacity of at least a portion of the
person contacting surface 52 below about 140 W/m.sup.2.
[0057] In yet a further example, a support device 12 is provided.
The support device 12 includes a cover 40 and a spacer 48. The
cover 40 defines an interior region 42 and at least a portion of
the cover 40 defines a person contacting surface 52. The cover 40
also defines a fluid permeability parameter, a thermal conductivity
parameter, and a thickness parameter. The spacer 48 is positioned
within the interior region 42. The spacer 48 defines a fluid
resistance parameter, a fluid permeability parameter, a thermal
conductivity parameter, and a thickness parameter. At least one of
the fluid permeability parameter of the cover 40, the thickness
parameter of the cover 40, the thermal conductivity of the cover
40, the fluid resistance parameter of the spacer 48, the fluid
permeability parameter of the spacer 48, the thermal conductivity
parameter of the spacer 48, and the thickness parameter of the
spacer 48 is varied to cooperate with the fluid supply 62 to
maintain a heat withdrawal capacity of at least a portion of the
person contacting surface 52 below about 140 W/m.sup.2.
[0058] Any theory, mechanism of operation, proof, or finding stated
herein is meant to further enhance understanding of the present
disclosure and is not intended to make the present disclosure in
any way dependent upon such theory, mechanism of operation, proof,
or finding. It should be understood that while the use of the word
preferable, preferably or preferred in the description above
indicates that the feature so described may be more desirable, it
nonetheless may not be necessary and embodiments lacking the same
may be contemplated as within the scope of the disclosure, that
scope being defined by the claims that follow. In reading the
claims it is intended that when words such as "a," "an," "at least
one," "at least a portion" are used there is no intention to limit
the claim to only one item unless specifically stated to the
contrary in the claim. When the language "at least a portion"
and/or "a portion" is used the item may include a portion and/or
the entire item unless specifically stated to the contrary. While
the invention has been illustrated and described in detail in the
drawings and foregoing description, the same is to be considered as
illustrative and not restrictive in character, it being understood
that only the selected embodiments have been shown and described
and that all changes, modifications and equivalents that come
within the spirit of the invention as defined herein or by any of
the following claims are desired to be protected.
* * * * *