U.S. patent application number 12/960493 was filed with the patent office on 2011-03-31 for anatomical, pressure-evenizing mattress overlay with prestressed core, and baffled, lateral-edge core respiration.
This patent application is currently assigned to MJD Innovations, L.L.C.. Invention is credited to Casey A. Dennis, Michael R. Dennis.
Application Number | 20110072589 12/960493 |
Document ID | / |
Family ID | 43778670 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110072589 |
Kind Code |
A1 |
Dennis; Casey A. ; et
al. |
March 31, 2011 |
ANATOMICAL, PRESSURE-EVENIZING MATTRESS OVERLAY WITH PRESTRESSED
CORE, AND BAFFLED, LATERAL-EDGE CORE RESPIRATION
Abstract
An anatomical pressure-evenizing mattress overlay including a
dynamic-response core having spaced, upper and lower, surfaces and
an intermediate, perimetral edge. The core is formed including a
100% open-cell, compressible and flowable, viscoelastic foam
expanse, and possesses a relaxed-state volume which resides in
about an 8-10% nominally compressed condition. Load-transmissively
bonded to the entire outside of the core, so as to function as a
dynamically-responsive unit with it, and possessing a
relaxed-state, internal, prestressed, tension condition, is an
elastomeric, moisture- and gas-flow-managing coating, including
fluid-flow-controlling, baffled, respiration window structure which
exposes a portion of the core's edge to accommodate respiration of
and for the interior of the core.
Inventors: |
Dennis; Casey A.; (Sequim,
WA) ; Dennis; Michael R.; (St. Helens, OR) |
Assignee: |
MJD Innovations, L.L.C.
Scappoose
OR
|
Family ID: |
43778670 |
Appl. No.: |
12/960493 |
Filed: |
December 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12798390 |
Apr 2, 2010 |
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12960493 |
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12657568 |
Jan 21, 2010 |
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12798390 |
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61206126 |
Jan 28, 2009 |
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Current U.S.
Class: |
5/691 |
Current CPC
Class: |
A47C 27/14 20130101 |
Class at
Publication: |
5/691 |
International
Class: |
A47C 27/14 20060101
A47C027/14 |
Claims
1. An anatomical pressure-evenizing mattress overlay comprising a
dynamic-response core expanse having spaced, upper and lower,
surfaces and a perimetral edge extending between said surfaces,
formed of a 100% open-cell, compressible and flowable, viscoelastic
foam, and having a relaxed-state volume in the overlay which is
prestressed, and about 8-10% compressed, thus to create a
pre-compression condition in the expanse, and an elastomeric,
moisture- and gas-flow-managing coating, including respiration
window structure operatively associated with said core expanse's
said perimetral edge, load-transmissively bonded to the entirety of
the outside of said expanse to function as a dynamically-responsive
unit with the expanse, and possessing a relaxed-state, internal,
prestressed, tension condition.
2. The overlay of claim 1, wherein said core expanse is elongate
and includes opposite ends, and said respiration window structure
includes a pair of laterally baffled windows disposed, one each,
adjacent said core expanse's said opposite ends.
3. The overlay of claim 2, wherein the lateral baffling for said
windows includes, suitably anchored to said coating, and for each
window, (a) a pair of laterally spaced, outwardly projecting baffle
filter blocks disposed adjacent laterally opposite sides of the
window and formed of the same viscoelastic foam material which is
employed in said core expanse, and (b) an expanse of transparent
adhering tape bridging the space between said blocks, and anchoring
the blocks to said coating via attachment of the tape both (1) to
portions of said blocks and (2) to portions of said coating which
overlie the upper and lower surfaces of said core expanse adjacent
the window.
4. The overlay of claim 3, wherein each pair of baffle filter
blocks and the associated adhering tape define an enclosed baffle
chamber in fluid communication with the associated window.
5. The overlay of claim 3, wherein each of said core expanse's said
upper and lower surfaces has an area A, and said two windows
collectively have an area which is approximately 0.0013 A.
6. The overlay of claim in 1, wherein said respiration window
structure includes a perimetral band of thinness in said coating
extending around the perimetral edge of said core expanse generally
centrally intermediate the core expanse's said upper and lower
surfaces, said band being edge-defined by spaced, upper and lower,
baffle-function edges formed in thicker regions in said
coating.
7. The overlay of claim 1, wherein said core expanse exhibits a
compressive-deflection vs. compression-force curve which includes
an extremely linear region over which a relatively wide change in
compressive deflection is accompanied by what turns out to be an
anatomically insignificant change in compression pressure.
8. The overlay of claim 1, wherein said core expanse is
specifically formed of a polyurethane material.
9. The overlay of claim 1, wherein said upper and lower surfaces
are, allover, substantially equidistant.
10. The overlay of claim 1, wherein said expanse has a thickness
throughout of about 1-inches.
11. The overlay of claim 1, wherein said expanse has opposite broad
faces linked by a perimetral edge, and said coating, where it
covers said broad faces, is formed so as to be substantially both
moisture-impervious and gas-impermeable, and where it covers said
edge so as to be, at least in its included respiration window
structure, both moisture-resistant (but moisture-pervious) and
gas-permeable.
12. The overlay of claim 11, wherein said coating throughout
possesses a plurality of approximately 0.001-inches thick sublayers
including next-adjacent sublayers joined though initially wet,
interfacial surfaces of joinder.
13. The overlay of claim 1, wherein said coating has an outer
surface which is characterized by an overall distribution of
suction-cup-like dimples.
14. An anatomical pressure-evenizing mattress overlay comprising a
core expanse of single-density, 100%, open-cell, compressible and
flowable, polyurethane, viscoelastic foam, and an at least
partially gas-breathable, elastomeric coating extending over the
entirety of the surface area of said core expanse, and
interfacially, mechanically bonded to said surface area, said
coating being everywhere in tension and placing said core expanse
everywhere in compression.
15. An anatomical pressure-evenizing mattress overlay comprising a
prestressed, dynamic-response core assembly having spaced, upper
and lower, surfaces and a perimetral edge extending between said
surfaces, formed with (a) a first core expanse made of a 100%
open-cell, compressible and flowable, viscoelastic foam disposed
adjacent said upper surface, (b) a second core expanse made of a
different, closed-cell, viscoelastic foam disposed adjacent the
opposite side of said first core expanse relative to said upper
surface, and (c) a third core expanse made of yet another,
closed-cell, viscoelastic foam disposed adjacent said core
assembly's lower surface and the opposite side of said second core
expanse relative to said first core expanse, said core assembly
having a relaxed-state volume in the overlay which is prestressed,
and about 8-10% compressed, thus to create a pre-compression
condition in the core assembly, and an elastomeric, moisture- and
gas-flow-managing coating, including respiration window structure
operatively associated with said core assembly's said perimetral
edge, load-transmissively bonded to the entirety of the outside of
said assembly to function as a dynamically-responsive unit with the
assembly, and possessing a relaxed-state, internal, prestressed,
tension condition.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/798,390, filed Apr. 2, 2010, for
"Anatomical, Pressure-Evenizing Mattress Overlay and Associated
Methodology", which is a continuation-in-part of U.S. patent
application Ser. No. 12/657,568, filed Jan. 21, 2010, for
"Anatomical, Pressure-Evenizing Mattress Overlay", which claims
filing-date priority to prior-filed U.S. Provisional Patent
Application Ser. No. 61/206,126, filed Jan. 28, 2009, for
"Anti-Decubitus-Injury Mattress Overlay". The entire disclosure
contents of these three, prior-filed applications are hereby
incorporated herein by reference.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] The present invention pertains generally to an anatomical,
pressure-evenizing mattress overlay with a prestressed core, and
baffled, lateral-edge core respiration windowing. More
particularly, and with these generally-stated features solidly in
place, it relates to a special-purpose, special-capability,
breathable, friction- and shear-controlling, anatomical-support,
pressure-evenizing, "mattress overlay" intended to be placed on top
of, and used in conjunction with, an underlying, yieldable support
surface, such as that provided by a mattress, for the purpose of
furnishing "direct", pressure-evenizing under-support for a
substantially bed-ridden person. Respiration-window structure, and
associated baffling, are employed to control cooling air-flow
(gas-flow breathability) in the overlay-internal core structure for
cooling and keeping perspiration-free a supported person, with the
baffling also functioning to minimize (hopefully to prevention) the
penetrating leakage of supported-person body liquid into that core
structure. The concept of structural breathability, featured by the
invention, is also intentionally referred to herein,
pseudo-anagogously, in the language of "respiration"--a term most
usually associated with human (or other animal) breathing.
[0003] In one of its important aspects, the present invention
involves an improved version of the invention described in the
above-referenced '568 application, and in another important one of
its aspects, it proposes an improved version of the invention
described in the above-referenced '390 application.
[0004] The overlay of the invention, in its preferred "thickness"
configuration, is specifically designed, as will be explained more
fully below, with a thickness (or thinness, depending on point of
view) suitable, with the provision of appropriate, external
yieldable under-support, for handling persons weighing up to about
350-lbs. In this configuration, it is definitively not designed to
be used alone as a support on top of any rigid, underlying surface;
nor is it intended to be a "stand-alone" support structure, such as
a mattress, per se.
[0005] Where heavier persons are to be handled, such situation may
be addressed either in the manner described in the above-referenced
'390 patent application, i.e., through the use of an external
bariatric support structure, or may be accommodated differently,
according to the present invention, by employing a herein
illustrated and described, modified, plural-layer-core, thicker
overlay structure which, for such a "heavy-handling" requirement,
includes a different internal core formation that specially resists
inadvertent, and problematic, "bottoming-out". More will be said
later about these ways of dealing with this especially
heavy-weight, successful support matter.
[0006] For the more normal, "non-overly-heavy" supporting
condition, the overlay proposed by the present invention, in its
preferred and best-mode form, has a thickness which is no more than
about 1-inches. This preferred thickness militates against its
utilization respecting the "not-designed-for" uses just above
mentioned.
[0007] The term "bed-ridden" as used herein as a "person
characterization" is intended broadly to include a wide range of
differently convalescing persons who may spend significant amounts
of extended, body-support time not only specifically in hospital
beds, but also on and in conjunction with other bed-like mattress
structures.
[0008] Speaking with more particularity about the invention, and
about what we see to be its remarkable, and experimentally
demonstrated capability, it, the proposed "mattress overlay", has
as its special purpose the dramatic minimization of the onset and
development of decubitus ulcers (sores)--medical conditions that
lead to dangerous and potentially lethal injuries which come from
long-term body-rest/support conditions. Accordingly, the overlay of
the present invention is naturally, and particularly, well suited
for placement on top of conventional, long-term,
person/patient-support mattresses, such as hospital-bed
mattresses.
[0009] With regard to use of the overlay of the invention on a
conventional hospital-bed mattress, an interesting feature of the
invention, which will be discussed more fully below, is its ability
to stick relatively naturally, and without much potential for
lateral slipping, on the surface of such a mattress on account of
the fact that such a surface is typically defined by a smooth, gas-
and moisture-impermeable, moisture-proof, mattress-body cover, such
as a smooth vinyl cover. This propensity for overlay "stickage",
"or stiction", discussed more fully later herein, results from a
kind of distributed, "suction-cup" surface character which exists
in the outer coating layer in the overlay owing both to the manner
of coating fabrication and to the nature of the selected coating
material, per se. Undesirable sticking to an overlay-supported
person does not, for various reasons, occur. These reasons will
also be identified later in this disclosure text.
[0010] While such a hospital-bed setting clearly presents an ideal
use environment for the present invention, the defining term
"mattress overlay" is intended herein to refer to any overlay
structure constructed in accordance with the special and unique
features of the present invention which may be shaped, sized, etc.,
for use not only on top of an underlying, conventional mattress
structure, per se, but also in other similar environments where
nonambulatory people, such as convalescing patients, may lie
recurrently supported for long periods of time. The above-expressed
concept of "direct", underlying, person support, while it could
(and can) include the concept of direct-to-skin contact support,
herein more typically means support which is furnished, for
example, (a) "directly through" clothing (such pajamas, a hospital
gown, etc.), (b) through a bed sheet, or (c) through some
combination of these and like things.
[0011] Regarding the above-mentioned special purpose of the present
invention, it is now, and has been for some time, well recognized
that the medical issue involving the development of decubitus
ulcers in bed-ridden, etc., patients, often those people who are
still in the environment of a hospital recovering from some medical
event or condition, is an extremely serious problem--a problem
which has recently caught the significant negative attention of
medical-institutional (and related) insurance agencies who have
come to recognize that prevention of the development of such ulcers
is, in fact, quite possible, though through conventional approaches
very challenging. This "negative attention" has translated itself,
among other things, into agency refusals to offer/provide relevant
insurance coverage. While the just-mentioned term "quite possible"
is indeed true, real prevention--that is, effective real
prevention--heretofore has been almost prohibitively expensive
because of the fact that such prevention has, in reality, required
substantial, frequent, personnel-intensive, one-to-one, or
more-to-one, personal attendance to the changing of the resting
"positions" of "bed-ridden" persons at risk.
[0012] The decubitus ulcer (decubitus-onset, decubitus-injury,
decubitus-injury onset) problem is recognized today as being one of
the most serious problems facing hospital and medical-care
facilities, and these skilled care facilities are openly waging a
fierce battle with state and federal agencies and insurance
companies over who should pay the enormous costs in the treatment
of this "new epidemic."
[0013] In this setting, the prior art, of which we are aware, that
has been aimed at addressing the "decubitus-injury" problem is rich
with purportedly effective, proposed approaches for resolving it.
In practice, none appears to be particularly successful or
satisfactory, owing, as we perceive it, to the significant and
apparent failure to grasp a comprehensive understanding of the key
body-support environmental and contact conditions which must exist
if decubitus "onset" is to be avoided, or at least significantly
minimized. The present invention, we believe, "possesses" this
understanding.
[0014] Presently known (to us), patent-related pieces of this prior
art include: U.S. Patent Application Publication No. 2001/0034908
A1 of Duly, for "Mattress"; U.S. Pat. No. 5,031,261 to Fenner, Sr.,
for "Mattress Overlay For Avoidance of Decubitus Ulcers"; U.S. Pat.
No. 5,077,849 to Farley, for "Anatomically Conformable Foam Support
Pad"; U.S. Pat. No. 6,052,851 to Kohnle, for "Mattress For
Minimizing Decubitus Ulcers"; U.S. Pat. No. 7,356,863 to Oprandi,
for "Mattress Pad".
[0015] While these identified, prior-art approaches address, and
attempt to tackle with resolution, certain technical medical issues
and conditions that can lead to the development of a decubitus
injury (frequently referred to as a decubitus ulcer), clearly
taking aim at successfully minimizing costly medical-personnel
attention to "decubitus-at-risk" individuals, as far as we can
tell, no one has successfully developed a truly effective support
structure and/or methodology which has(have) the capabilities of
substantially eliminating the likelihood that such a decubitus
ulcer will develop.
[0016] The present invention changes this situation in a very
pronounced fashion. While readings and study of this prior art,
when compared with a reading of the present invention disclosure,
may appear at first glance, and on certain points, to reveal only
subtle differences, in reality these differences, in terms of
substantially solving the problem of decubitus onset, are anything
but subtle. Put another way, these differences "make the
difference"!
[0017] While there are probably many issues that are usefully
addressable in terms of preventing, or greatly limiting the
possibility of the onset of, decubitus ulcers, the three, key
considerations which we specially recognize in the characteristics
of the present invention involve:
[0018] (a) (1) avoiding even very short-term (minutes) of high,
applied anatomical pressure, (2) at all times pressure-evenizing
the contact-loading characteristics which define how the anatomy of
a bed-ridden patient is supported, and (3) specifically producing
an anatomical loading condition, static and dynamic, whereby there
exist substantially no notably high-pressure points (preferably
none exceeding about 32-mm Hg, and even more preferably not
exceeding about 20-mm Hg), and definitively no conditions involving
a projecting portion of the person's anatomy (i.e., a protuberance)
bottoming out against either a non-yielding, or relatively
non-yielding, underlying support surface, or in any manner
significantly raising (de-evenizing) anatomical support
pressure;
[0019] (b) minimizing friction and shear engagement between the
proposed overlay structure and a supported patient; and
[0020] (c), very importantly, providing effective,
fluid-control-baffled, ventilating, heat-removing,
perspiration-managing, cooling airflow (more broadly, cooling,
gas-flow respiration) in the volumetric region disposed immediately
beneath the supported anatomy so as to avoid the development of
hot-spots and overheating, and especially recognizing that those
portions of a supported anatomy, such as bony prominences, which
create notable, downward "indentations" in an underlying support
structure should be offered proportionally larger access to cooling
air (gas) flow.
[0021] Stressing this just-identified, third, heat-removal and
perspiration-managing, airflow-associated respiration concern, and
repeating, with emphasis, the "proportionally" greater airflow
comment just made above, it is especially relevant that the
points/areas/regions of underlying anatomical support which must
deal with the mentioned, notable, anatomical protuberances, and
especially with pronounced (i.e., relatively "sharp")
protuberances, be designed to furnish locally enhanced, rather than
more constricted, airflow within the anatomical support structure.
Put another way such protuberance-support areas are the ones that
potentially define the greatest risk for decubitus-ulcer
development, and as we have discovered, are the areas where the
most robust, ventilating airflow and air-circulation respiration
capability need to exist. Generally speaking, the greater the size
and/or "sharpness" of the protuberance, and thus the greater and
the deeper and the more angular the resulting support-surface
indentation, the greater the need for enhanced, support-structure
airflow and air-circulation capability.
[0022] Unfortunately, known and proposed prior art manners of
attacking the decubitus-ulcer problem do not recognize this
special, anatomical-protuberance-support observation of ours, and
failing that observation, actually propose supposedly
problem-resolving body-support structures and associated
methodologies which exacerbate the airflow respiration problem
associated with protuberance support by reacting to downward
protuberances with either no attention paid to airflow, or even
worse, increased constriction to airflow.
[0023] With this background in mind, the present invention takes
the form of an anatomical pressure-evenizing mattress overlay
including (a) a dynamic-response, preferably uniform-thickness core
expanse, or core, having spaced, upper and lower, surfaces and a
perimetral edge extending between these surfaces, formed of a 100%
open-cell, uniform-density compressible and flowable, viscoelastic
foam, and having a "relaxed-state" volume in the overlay which is
prestressed, by being about 8-10% compressed, to create a
pre-stressed, pre-compression condition in the expanse, and (b) a
differential-thickness (i.e., possessing different regions, or
portions, of relative thickness, as well as regions, or portions,
of relative thinness), elastomeric, vinyl coating having, due to
such differential thickness, specifically different
moisture-handling and gas-breathability, respiration-enabling,
respiration windowing characteristics furnished importantly at
different, selected locations in the overlay (as will shortly be
explained). This coating, which is referred to herein as an at
least partially gas-breathable coating, is load-transmissively,
interfacially bonded to the entirety of the outside surface area of
the core expanse to function as a dynamically-responsive unit with
the expanse--with the coating possessing a "relaxed-state",
internal, prestressed tension condition which is responsible for
the pre-stressed, pre-compression condition in the core
expanse.
[0024] As will be seen, the mentioned core-expanse prestressing
appreciably aids the critically important behaviors of
core-structure respiration, and supported-person cooling. The term
"relaxed-state" employed herein is used to refer to the conditions
of the overlay components when the overlay is not in use.
[0025] The core expanse is intendedly and preferably formed of a
specific-character, solid-phase, single-component, single-density,
polyurethane material, shaped with its upper and lower surfaces
substantially equidistant (i.e., the core expanse has preferably a
uniform thickness) to give the overlay, as a whole, a substantially
uniform thickness of no more than about 1-inches, with the
differential-thickness coating having a lesser thickness (i.e., a
portion, or portions, of thinness) of about 0.01-inches on certain
respiration windowing regions of the overlay edges, and a greater
thickness (i.e., a portion, or portions, of thickness) of about
0.02-inches elsewhere. These are all, certainly, dimensional
matters of user choice, but they have specifically been found by us
to be very useful, and consequently "preferred".
[0026] Regarding the matter of differential coating thickness, two
different, respiration-window-including, coating formations are
proposed in different versions of the overlay that are described
and illustrated herein. In one, the coating is defined with an
elongate, continuous, diminished-thickness, respiration-windowing
band (or, from another point of view, plural, elongate,
end-connected, overlay-side bands) extending around the perimetral
edge of the overlay. This band is also referred to herein as a
perimetral band of thinness. The two, thickened, spaced, coating
edges which define this band (or these bands) offer a respiration
baffling function, are also referred to herein as baffle-function
edges, and may be thought of as being a form of
moisture-and-gas-control baffle structure.
[0027] In the other, the coating has, preferably, only a pair of
very small, opposite-end (which may be thought of as "head-end" and
"foot-end" parts of the overlay, though the overlay has no such
specific "end" designations), edge-disposed, diminished-thickness
portions, referred to as windows and as respiration window
structure, each masked by a special, window-specific,
moisture-and-gas-controlling baffle, or baffle structure. This
special baffle structure takes the form of a sacrificial baffling
assembly which offers a visibility, liquid-leakage, tell-tale
function (relative to potential liquid leakage into the overlay
core structure through the baffle-associated window structure),
and, as will be later explained herein, is sacrificial in the sense
that it is easily and repeatedly replaceable when such a leakage
condition has been detected.
[0028] These relatively small respiration windows in this
second-mentioned coating embodiment offer the additional, useful
effect of promoting a kind of pneumatic resistance to
core-structure compression as a supported person adjusts position
on the overlay.
[0029] Accordingly, and for important structural and performance
reasons which will be explained later herein regarding the coating,
immediately outwardly (from the core expanse) beyond an initially
created, overall primer sublayer (which flows bindingly into the
core expanse material--an open cell foam material), the coating,
distributed in an all-over configuration relative to the core
expanse, is formed therefore on both the overlays' perimetral edges
and on its broad-surface areas, and specifically is preferably
formed with ten, approximately 0.001-inches thick, cured,
sublayers. These ten sublayers, further, are preferably
spray-applied, one over another, under "wet-form", interlayer
bonding circumstances, where the "previously applied",
next-spray-receiving sublayer, including the mentioned primer
sublayer (which adds substantially no depth to the coating, per
se), is still wet and not yet cured. The ten sublayers define the
"diminished-thickness" portions of the coating just mentioned
above.
[0030] In some instances, less than ten, for example about six,
sublayers may be used, resulting both in lesser material usage in
overlay manufacture, and in somewhat greater respiration
flowability, without appreciably diminishing needed overlay
thickness.
[0031] Staying with the ten-sublayer construction for more detailed
description purposes, different-thickness (greater-thickness)
coating portions cover the two, broad-surface areas (each having
what is referred to herein as an area A) in the overlay, as well as
certain portions (differing in the two, different coating
formations generally described above) of the overlay's perimetral
edge regions. These thicker coating portions, which furnish
moisture-shielding (impervious), core-protection, include outer,
eleventh, individually thicker (about 0.01-inches) sublayers which
are sprayed onto the immediately underlying, ten, thinner,
"all-over, basic" sublayers after those underlying basic sublayers
have dried.
[0032] The just-mentioned, wet-interlayer sublayer joinder
methodology (and arrangement) employed in relation to the
preferred, ten, basic sublayers in the coating produces,
structurally, a final, cured, layered coating having, between
substantially all next-adjacent, basic sublayers, and between the
innermost, basic sublayer and the primer sublayer, what we refer to
structurally herein as being finally cured, but initially wet,
interfacial surfaces of joinder. We have found that this special
type of wet, interfacial joinder structure enhances not only the
gas-breathability characteristics of the overall coating, but also,
importantly, the controlled shrinkage of the coating to produce the
desired level of coating-internal tension, and
core-expanse-internal compression. The one "area", however, and as
was just pointed out, of the prepared coating wherein the
wet-interfacial joinder approach is not employed involves the
application to each of the broad facial areas in the overlay of the
final, eleventh coating sublayer.
[0033] Interestingly, and as was mentioned/suggested briefly above,
when the outer layer has finally cured, it presents a special,
exposed surface characteristic which outwardly presents an overall
distribution of extremely tiny, i.e., essentially microscopic,
suction-cup-like indentations. These indentations, quite by
surprise, cause the overlay of the invention, when it rests upon
the typically smooth, moisture- and gas-impermeable surface of the
usual hospital-bed-mattress cover, to stick to that cover, through
suction-cup action, tenaciously against lateral slippage. This
sticking behavior furnishes a work-saving "blessing" to care
personnel who must, as part of their "patient vigil", be certain
that an employed overlay remains properly in place beneath a
supported person whose motion-restlessness might otherwise cause it
to migrate precariously over the surface of its own
undersupport.
[0034] Regarding the selectively differential gas-breathability
aspects of the proposed coating (i.e., what may be thought of as
being the coating "permeability-differentiating" features), the two
(upper- and lower-face) broad-area regions of the coating in the
overlay, and the extra-thickness coating sublayers which join with
these broad-area regions at certain locations, are structured with
their respective, eleventh, outermost, 0.01-inch-thickness
sublayers formed so as to be substantially both moisture-impervious
and gas-impermeable in nature, whereas the associated, ten,
next-inner, "basic" sublayers are structured to be both
moisture-resistant (but moisture-pervious) and gas-permeable. The
"basic" sublayers, where not covered by the eleventh sublayer,
function, in both of the described coating versions, as respiration
windows to and for the core structure.
[0035] One practical and successful way of creating the coating to
possess the mentioned sublayers with the respective, desired
thicknesses and differential-permeability characteristics is set
forth later herein.
[0036] The detailed description of the invention which follows
below will describe fully the features of, and the importances
attached to, the matters of core-expanse-material flowability,
coating tension, core-expanse compression, coating-core-expanse
mechanical binding to one another, and coating
"permeability-differentiating" features.
[0037] The overlay, per se, which is elongate and generally planar
in nature, and as has already been mentioned, has no preferential
upper or lower end. Nor does it have any preferential top or bottom
face, or side. It can, accordingly, confidently be placed with and
in any suitable orientation on an appropriate supporting
under-structure.
[0038] Functionally, and as will become very fully apparent, the
invention features an overlay structure for furnishing
pressure-evenized, dynamic-reaction support for the anatomy, which
structure, in use, importantly supports the anatomy with a 100%
open cell, polyurethane, viscoelastic foam that reacts to both
static and dynamic, anatomical-unevenness-produced indentations in
it to expand and contract foam-cell-openness size relatedly,
whereby deeper and sharper foam indentations result in greater
cell-openness size to promote significant, indentation-related
core-structure air-flow "breathing" (i.e., respiration). Nominal
compression in the core structure, and nominal tension in the
coating structure, cooperate, and greatly assist this respiration
behavior.
[0039] These and other features and advantages that are offered by
the present invention will become more fully apparent as the
detailed description which now follows is read in conjunction with
the accompanying drawings.
DESCRIPTIONS OF THE DRAWINGS
[0040] FIG. 1 is a simplified, isometric view of an anatomical
pressure-evenizing mattress overlay constructed in accordance with
one preferred and best-mode embodiment of the present invention
resting upon a fragmentarily shown hospital-bed mattress, and with
a portion of one corner of the illustrated overlay broken away to
illustrate details of internal construction. Components here are
not necessarily shown to scale relative to one another.
[0041] FIG. 2 is a larger scale, fragmentary, cross-sectional view
taken generally along the line 2-2 in FIG. 1.
[0042] FIG. 3 is an even larger-scale, fragmentary illustration of
the region generally embraced by the two, curved arrows 3-3 in FIG.
2.
[0043] In FIGS. 2 and 3, it is also the case that the various
overlay components are not necessarily drawn to scale.
[0044] FIG. 4 is a simplified, fragmentary view, drawn on about the
same scale which is employed in FIG. 2, illustrating anatomical,
load-bearing response of the overlay of FIGS. 1-3, inclusive, and
especially showing how the dynamic-response core of the overlay of
the present invention responds to such loading. What is shown in
FIG. 4 should be read along especially with what is seen in FIG.
1.
[0045] FIG. 5 is a simplified, fragmentary, isometric view in view
of another preferred and best-mode embodiment of an anatomical
pressure-evenizing mattress overlay constructed in accordance with
the invention, this overlay also being shown resting upon a
fragmentarily illustrated hospital-bed mattress. Portions of
coating structure in this overlay have been broken away to reveal
the internal core structure. This figure, which is drawn on about
the same scale as that employed in FIG. 1, does not necessarily
illustrate pictured components in correct proportions relative to
one another. The embodiment pictured here includes both the
above-mentioned, overlay-end-disposed, respiration window
structure, and the also above-mentioned, special, sacrificial,
tell-tale, respiration-window baffling structure.
[0046] FIG. 6 illustrates a pre-shaping, pre-installation
preparedness condition of an isolated, respiration-window baffling
assembly including a pair of baffle filter blocks and transparent
adhering tape in their configuration and conditions relative to one
another immediately before attachment of this assembly to form the
lateral baffling structure, and an enclosed baffle chamber, for the
respiration window structure which is pictured in and for the
overlay shown in FIG. 5.
[0047] FIG. 7 is an enlarged-scale, fragmentary cross section
showing a modified form of core structure in a modified overlay
constructed in accordance with yet another embodiment of the
invention, specifically showing an embodiment which is designed to
handle large, overweight persons.
DETAILED DESCRIPTION OF THE INVENTION
[0048] Turning attention now to the drawings, and referring first
of all to FIGS. 1-3, inclusive, indicated generally at 10 is one
preferred and best-mode embodiment of an anatomical,
pressure-evenizing mattress overlay constructed in accordance with
the present invention. Overlay 10 herein has an overall thickness
of about 1-inches (a preferred maximum thickness), a lateral width
of about 36-inches, and a length of about 75-inches. Each broad
face of the overlay has an area A, not specifically labeled in the
drawings. Overlay 10 is formed, basically, from two different
components, or portions, including a single-piece, dynamic-response
core expanse, or core, 12, and a "differentiated character",
elastomeric coating 14 whose differentiated features, which relate
to thickness, moisture-handling, and gas permeability/respiration
(and consequently heat-removal handling) will shortly be described.
Coating 14, as will shortly be explained, is load-transmissively
(mechanically), interfacially (face-to-face) bonded to the
entireties of the outside broad-planar-facial and edge-surface
areas of expanse 12. The broad-planar-facial areas in core expanse
12 are shown at 12a, 12b, and the edge-surface area, which is full
perimetral in nature, is shown at 12c.
[0049] In FIGS. 1 and 2, overlay 10 is shown resting upon a
hospital-bed mattress of conventional construction shown generally,
and fragmentarily-only, at 16 in these two drawing figures. The
main body of mattress 16 herein is covered with a conventional,
smooth-surfaced, gas- and moisture-impervious cover 16a. As has
been mentioned earlier herein, the mattress overlay of this
invention need not necessarily be used in the setting of a
conventional, hospital-bedding mattress, but may also be used,
appropriately perimetrally shaped, to fit into other environments
involving convalescing patients. In all instances, it is important
that the mattress overlay of this invention be supported upon a
mattress-like support structure, or other, similar, suitably
yieldable understructure, in order to prevent core expanse 12 from
bottoming out. Typically, though not necessarily, the overlay will
be employed with a thin, fabric, sheet-like jacket to furnish a
bed-sheet-like feeling to a supported person.
[0050] In this context, the about 1-inches thickness proposed
herein as being preferable for the core expanse has been chosen for
several reasons, one of which is that, when properly
under-supported, and as above described, it will readily handle a
person weighing about 350-lbs, and will also successfully deal,
without bottoming out, with notably projecting, angular portions of
the anatomy even involving persons of such weight. Under
circumstances where an especially heavy person, for example someone
who weighs more than about 350-pounds and up to about 500-lbs, is
to be supported in accordance with practice of the invention, it is
important that the overlay not be placed upon a hard and
non-yielding undersurface, or be used alone as a mattress with
stiff under-support. Such conditions could easily lead to
undesirable bottoming-out. Rather, a modified form of the overlay,
later to be described herein, should be used.
[0051] In addition to the mattress overlay of FIG. 1 having, as a
whole, a preferred thickness of about 1-inches in order to prevent
a bottoming-out situation, another important reason for choosing an
overlay thickness limited to about 1-inches in this embodiment of
the invention is that this is a thickness which works well to
assure maximum availability of the significant air-breathability
capabilities of the selected overlay components.
[0052] According to one very important feature of the present
invention, core expanse 12 is formed of a 100% open-cell,
single-density, viscoelastic foam, most preferably made from the
product known as #5010 CF Visco, polyurethane, Domfoam made by
Domfoam International, Inc. in Montreal Quebec, Canada. This foam
is both compressible and flowable. Significantly, this foam which
has been chosen for the core expanse has another, very important,
internal structural character whereby, under changing
compression-pressure conditions, it exhibits a
compressive-deflection vs. compression-force (or load) curve which
includes an extremely linear region over which a relatively wide
change in compressive deflection is accompanied by what turns out
to be an anatomically insignificant (i.e., only slightly
perceptible) change in compression pressure. This feature plays a
very important role in assuring evenized support pressure applied
statically and dynamically to the underside of a supported anatomy,
notwithstanding the presences of, say, any bony anatomical
protrusions.
[0053] For a reason which will now be explained, and as has already
been mentioned above, core expanse 12, within the overall structure
of overlay 10, is in a pre-stressed compressed condition, with a
"relaxed-state" compression internally of about 8-10%. This
compression is brought about by virtue of the presence of allover
overcoating by coating 14 which is a multi-sublayered, sprayed-on,
elastomeric, vinyl coating prepared with a "varied" overall
thickness, as was mentioned earlier, and as will be more fully
explained shortly, lying preferably in the range expressed earlier
herein of about 0.01-inches to about 0.02-inches. Coating 14
preferably is made from a vinyl material such as that manufactured
and sold by PlastiDip International in Blaine, Minn. under the
identity Miraculon PDF-830. As was also mentioned earlier herein,
coating 14 is prepared, illustratively and preferably, and in
certain different regions of the coating, with different
pluralities, and different, overall thicknesses, of sublayers, most
of which (i.e., the "basic" sublayers), individually, have
thicknesses of about 0.001-inches, and a few of which have the
greater sublayer thickness which is employed herein of about
0.01-inches--these different sublayer pluralities and thicknesses
accounting for the coating's "varied, or differential, thickness"
nature.
[0054] The coating is formed, almost throughout, in a special
manner to ensure several important structural and performance
features. One of these features is that, except in those coating
regions included in the broad-area portions of the overlay, and in
thicker-coating portions of the perimetral edge regions of the
overlay, a special, inter-sublayer joinder exists between each of
the sprayed-on sublayers to improve moisture-handling,
gas-breathability, and attendant heat-removal and
perspiration-management capabilities of the coating. Another of
these features is that the coating, when completed, demonstrates a
controlled shrinkage which is responsible for placing core expanse
12 into nominal, overall compression, and the coating into a
nominal prestressed, tensed condition.
[0055] In the just-mentioned, broad-area and perimetral-edge
thicker portions of the overlay, a different inter-sublayer joinder
structure exists between the outermost sublayer, and the immediate
next-inner sublayer. This will be more fully described shortly.
[0056] In the embodiment of the invention now being described, the
coating-structure regions which cover facial areas 12a, 12b in the
core expanse, as well as those which cover certain (upper and lower
as seen in FIGS. 1 and 2) portions of perimetral edge area 12c,
have outer sublayers that differ somewhat in construction from that
of the outermost sublayer regions of coating 14 which cover the
vertically central, "horizontally elongate", clearly visible,
band-like, or band, portions of perimetral edge area 12c in the
core expanse.
[0057] Directing attention specifically to FIGS. 2 and 3, here
fragments of core expanse 12, and of different portions of the
plural-sublayer construction of coating 14, are illustrated.
Coating 14 includes (a) two, broad-area, about 0.02-inches-thick,
facial portions 14A which extend over and cover facial areas 12a,
12b in core expanse 12, (b) two, elongate, vertically spaced,
0.02-inches-thick, perimetral edge stretches 14B which extend over
and cover spaced upper and lower parts of perimetral edge-area 12c
in the core expanse, and (c) an elongate, vertically central, about
0.01-inches-thick, perimetral edge band 14C which extends over and
covers that portion of the core expanse's perimetral edge-area 12c
which lies between coating stretches 14B. The vertical dimensions
of coating stretches 14B, and band 14C are substantially equal with
dimensions each of about 1/3-inches--the term "vertical" herein
relating generally to the orientations of FIGS. 2 and 3.
[0058] Coating stretch 14C may be thought of as being one
continuous, elongate, overlay-perimetral band of thinness in the
coating, or as an endo-connected collection of overlay
edge-side-specific, plural bands of thinness therein, and this
stretch is referred to herein as a window, as a respiration window
structure, and as a baffled, respiration window structure. The
spaced, confronting edges of coating stretches 14B which evidently
define this band-like window structure are referred to herein also
as baffle-function edges which laterally baffle the associated
window structure to control fluid flow (liquid and gas) through the
window structure into and out of the core expanse.
[0059] FIG. 3 illustrates, more particularly, the respective
constructions of coating portions and stretches 14A, 14B, 14C.
[0060] Each of these three coating portions/stretches commonly
includes (1) a primer sublayer 14a (shown in dashed lines) which
has penetrated the adjacent outer portion of core expanse 12, and
which adds no appreciable thickness to the coating, and (2) ten,
joined, thin, "basic" sublayers, such as the two, basic sublayers
shown at 14b. An interfacial bond (of the special, "wet-form"
nature mentioned above), one of which is shown by a heavy line 14c
in FIG. 3, exists between each of these just-mentioned primer and
"basic" sublayers. This special interfacial bond is referred to
herein as being defined by "initially wet", interfacial surfaces of
joinder.
[0061] Coating portions 14A and stretches 14B, alone among the
regions in coating 14, include the previously-mentioned,
additional, eleventh, thicker outer sublayer, such being pictured
at 14d in FIG. 3. Sublayers 14d in these coating portions and
linked stretches form, in coating 14, a kind of cap, or capping
structure, which "receives", to about one-third each the overall
core-expanse thickness, the opposite facial zones in the
core-expanse structure. Such capping structure(s), and particularly
the edge stretches therein, define the above discussed, laterally
vertically-central breathing and moisture-venting respiration
window band, or bands in the overall overlay structure.
[0062] Coating region 14C includes only the combination of primer
sublayer 14a and each of the ten, basic, thin sublayers 14b.
[0063] A consequence of this construction is that coating portions
14A and stretches 14B preferably have overall thicknesses herein of
about 0.02-inches, whereas coating portion 14C has preferably an
overall thickness of only about 0.01-inches.
[0064] As illustrated in FIG. 3, whereas all of the sublayers that
are there pictured within the illustrated coating portions have
been shaded similarly to make them easily readable as individual
sublayers, outer, thick sublayer 14d is different internally, in
that it is constructed to have somewhat different gas-permeability
and heat-removal behaviors than those like-character behaviors of
each of the next ten, other, underlying sublayers. More
specifically, sublayer 14d has-been prepared so as to be,
essentially, both moisture-impervious and gas-impermeable in
nature, whereas the next ten, underlying, other sublayers, the
so-called basic sublayers, have been prepared differently so as to
be moisture-resistant (i.e., not impervious to moisture) and
gas-permeable in nature.
[0065] Describing now the process preferably employed to create the
different sublayers in the different regions, or portions, of
coating 14, generally speaking, there are two, different spraying
arrangements which are used during coating creation. One of these
involves supporting a flat expanse of "material" (i.e., either an
initial, not yet in any way coated, flat expanse of the mentioned
core material alone, or, a flat expanse of partially coated core
material) on a generally horizontal table, and producing linear,
repetitive, plural-cycle relative motion between an overhead
plurality of appropriately laterally and vertically
spaced/distanced spray heads and the material-supported material
expanse. This is preferably accomplished by holding the table and
supported material stationary, and moving the spray heads. The
other arrangement involves supporting a material expanse (by this
time partially coated, as will be explained) in what might be a
somewhat clamp-like jig, and producing relative rotational motion
between the so-supported expanse and, typically, a single spray
head, appropriately distanced so as to create the perimeter edge
portions of the desired coating.
[0066] Preferably, spraying takes place, utilizing conventional
Devilbiss spray-equipment spray guns (or spray heads) each with a
#704 cap and a 0.055 spray tip and needle, in an environment which
has a temperature of around 65.degree. F., with a blend of air and
the above mentioned Miraculon spray product supplied for spraying
at the same temperature which is essentially. Environmental
humidity preferably lies at about 25%. Throughout spraying, air and
Miraculon are supplied to the spray-heads at respective flow
pressures of 80-psi and 50-psi. As will be pointed out below,
during different steps of spray-application, spray gun control
valves are operated variously either fully open with respect to the
supply of Miraculon, or "throttled down" to substantially 1/3-open
conditions.
[0067] Further describing general spray-application conditions, it
is preferable that the spray heads be disposed at a distance from
the "target structure" by about 10- to about 12-inches, with the
spray head organization which is employed during spraying
broad-expanse areas of "target structure" being spaced by a
distance whereby their respective sprays, where these strike the
target, overlapping one another by about 50-percent. It is also
preferable that relative (liner and rotational) motion, depending
upon where spraying is taking place, at the rate of about
3-inches-per-second, be used between the spray-head structure and
the structure being spray coated.
[0068] Coating preparation begins by placing a not yet edge-sized,
i.e., not yet perimeter-sized, expanse of the above-mentioned
Domfoam material on a horizontal table, and by then applying to the
exposed broad surface area of the expanse, and first of all, a
primer sublayer 14a of Miraculon material with the valves in the
spray-heads fully open, and with "primer spraying" occurring in a
single pass over the mentioned, exposed expanse area. This primer
sublayer soaks into the Domfoam expanse to create a tenacious,
mechanical bond directly with that expanse, leaving a wet surface
exposed on the face of the expanse, but exhibiting no appreciable
"external" depth (i.e., outwardly of the core expanse).
[0069] This primer sublayer spraying is immediately followed, while
the primer sublayer material is still wet and uncured, with ten,
successive next-adjacent-sublayer spray-head passes over the same,
exposed expanse area, with the only difference being that the
spray-head valves, in each pass, are throttled down to their
above-mentioned 1/3-open conditions. Each of these next ten spray
passes follows the immediately preceding pass while the
last-applied sublayer is still wet and uncured to create the
"wet-form", inter-sublayer bonds 14c. Each of these next, ten,
"throttled-down", "wet-interface" passes produces a Miraculon
sublayer 14b having a thickness of about 0.001-inches, and which is
characterized with a quality of open "stringiness".
[0070] Following the procedure which has just been described
relative to one broad surface of a Domfoam expanse, a spraying is
paused for a period of about 30-minutes to allow the layers of
material that have just been sprayed to dry and cure more
thoroughly. Thereafter, the expanse is turned over and the process
just described is repeated in its entirety to create a similar
multi-sublayer coating on the opposite broad face of the expanse.
This repeated procedure is followed by a similar pause in spraying
as was just mentioned.
[0071] Thereafter, the Domfoam core expanse, which now has, on its
opposite, broad faces, an almost completed coating (complete except
for missing just the final, eleventh, thicker outer sublayer 14d),
is allowed to "rest" for about 24-hours to enable all then-applied
basic sublayers to cure substantially, and is then appropriately
trimmed to have the correct perimetral outline.
[0072] The perimeter-trimmed expanse is next placed in a suitable
supporting jig, which may take the form of a broad-platen clamping
jig, for controlled relative rotation, first, in a single rotation
cycle past a spray head (which is fully open) to apply an edge
primer sublayer 14a, followed in quick succession by ten additional
rotation cycles (with the spray head throttled down to a 1/3-open
condition) to apply the intended, ten, edge-coating, wet-bonded
sublayers 14b. Spraying is now paused for the same,
above-mentioned, about 30-minute time interval, and for the same
reason.
[0073] At this point in the coating process, the coated structure
which has been created so far is broad-surface supported on a
horizontal table, one side at a time, and sprayed on each broad
surface with the spray heads in fully open conditions, and in a
single spray pass per side, to create the required, about
0.01-inches thickness, final, eleventh, outer broad-area coating
sublayers 14d. A spraying pause interval, here of about 24-hours,
is interposed the spraying of these two broad surfaces.
[0074] What next occurs is that, effectively for each edge of the
overlay structure formed so far, and with that partially completed
overlay structure resting in a substantially horizontal plane, an
elongate, about 1/4-inch-diameter, metal (or plastic) rod (or the
like) is suitably supported in a condition substantially
horizontally disposed, parallel to and closely adjacent the edge,
and vertically centered relative to the upper and lower broad faces
of the structure, so as to furnish a "spray-shadow" mask which will
be employed now for the purpose of assisting in the creation, along
the relevant edge, of the two, separated, upper and lower coating
stretches 14B, and the associated, separating edge band 14C. This
"rod-masking" may be performed (for spraying) either (a) on an
edge-by-edge, single-edge basis, or (b), for all four edges "at
once", utilizing a masking rod for each edge, or even a single,
suitably sized and angled, single, "bent", circumsurrounding
rod.
[0075] With rod-masking in-place, and with the overlay structure
suitably supported, along with the masking rod structure, in a jig
of the type generally mentioned earlier herein, a single spray pass
(per edge) of the type generally employed to create just-described,
thick coating sublayers 14d is implemented to create, around the
perimetral edge of the structure what may be thought of as
angularly intersecting, continuation portions of previously
created, broad-surface-area layers 14d, in order to create the
differential-thickness coating structure which is clearly
illustrated in FIG. 3 in the drawings.
[0076] After this final edge spraying has taken place, the
rod-masking structure is removed, and the entire, and all of the
various spray sublayers in the now fully spray-coated core expanse
are allowed to cure and dry even more thoroughly in an environment
whose temperature is about 95.degree. F., and for a period
preferably of about 3-5-days.
[0077] When sublayer spraying takes place in accordance with these
just mentioned and described, different spray-application
(parameter) considerations, the various sublayers evidence the
desired, differentiated gas-handling and moisture-permeability
characteristics generally described for them above. A clear
consequence of this coating-creation procedure is that different
regions in the coating behave differently. In the two, broad-area
portions 14A, and the two, vertically spaced, perimetral, edge
portions (stretches) 14B, of the coating, as far as the "outside
world" is concerned, relative to the overlay's internal core
expanse, there is a substantial moisture and gas-flow,
impermeability barrier. Immediately inwardly in these two areas,
however, i.e., immediately inwardly of the outer coating sublayer
14d in these areas, there is gas-breathability within the
basic-sublayer, internal portions of the coating extending inwardly
to adjacent the core expanse. In the vertically central, perimetral
edge areas (band) 14C of the coating, there is moisture resistance
(but not impermeability), and gas-breathability, through and
throughout this portion of the coating structure and in
communication with the core expanse.
[0078] These important coating considerations result in several
significant overlay conditions and behavioral features. In
particular, the resulting structural joinder which develops in the
interfacial regions between the individual, basic sublayers in
coating 14 offers improved gas-breathability in the relevant
regions mentioned above in the final structure of coating 14, and
further, promotes appropriately controlled shrinkage of coating 14
as a whole to create the different pre-stressed compression and
tension conditions mentioned above for the core expanse and the
coating, respectively.
[0079] Thin application of at least the first-to-be-sprayed-on
(i.e., core-expanse-contacting) primer sublayer regions in coating
14 causes the coating as a whole to bond robustly mechanically (in
a manner which we refer to as load-transmissively) to the entire
outside surface area of the core expanse, with the result that the
localized regions of joinder of the core expanse and the coating
function essentially as a unit everywhere within the overlay.
[0080] As mentioned briefly above, a surprise to us resulting from
the coating process which has just been described is that the outer
coating layer 14d, on curing, develops over its entire outside
surface a distribution of tiny, essentially microscopic,
suction-cup-like dimples, or suction cups. FIG. 1 in the drawings
generally, schematically, and entirely out of scale, illustrates
this surface condition at 17. These dimples furnish the
earlier-herein-mentioned anti-migration stiction which the overlay
of the invention advantageously demonstrates when it is placed on a
smooth support surface, such as that offered by the usual vinyl
cover provided for a hospital-bed-like mattress.
[0081] Adding reference now to FIG. 4 along with the other drawing
figures, this bonding condition produces an "in-use" action,
extremely important in the behavior of overlay 10, wherein
expansive stretching of the coating, such as that which occurs, for
example, when the anatomy, and particularly a sharp, anatomical
protuberance therein, depresses the overlay support surface (see
representative arrow 18 in FIGS. 1 and 4), pulls on the bonded core
expanse, and causes (a) core-openness size in that pulled-on and
resultingly expanded, core-expanse region to enlarge, and (b)
airflow openness in at least the innermost sublayers in the coating
to increase locally, thus immediately promoting increased airflow
capability and activity in that region. Prestress compression in
the core expanse importantly aids in this action, since that
compression urges the core expanse to swell non-resistively, and
expand. When the protuberance represented by arrow 18 engages the
overlay, and with an understanding that things are purposely
illustrated exaggeratedly in FIG. 4, it produces a significant
depression 14D in coating 14, and a matching depression in the
upper surface of core expanse 12. Given the modest thickness of the
core expanse, this depression "telegraphs" its presence to some
extent to the immediate underside of the expanse to produce the
gentle downward bulging in coating 14 shown at 14E.
[0082] This "depression/bulging" condition is characterized, of
course, by an expanding and stretching of the coating at the 14D,
14E locations therein, and attendant increasing of the there-local
airflow permeability of at least the internal sublayers in the
coating. This expanding and stretching, in addition to producing an
interesting and effective, internal, "bellows" air-flow condition,
causes related, outward, lateral "dragging" of the bonded core
expanse, aided in that "dragging" by the relaxation of compression
in that expanse. The squeezing which results in the core expanse
between locations 14D, 14E produces slight, lateral, outward
flowing of the expanse as indicated by arrows 20, 22, with
outwardly flowed core expanse-material represented in the two,
angular, lightly shaded region of that expanse shown at 24. 26.
[0083] Further considering air-flow (gas-flow) management features
of overlay 10, particularly with reference to how the broad-area
and vertically central, perimetral-edge regions of the core
structure perform, the fact that the thicker, outer sublayers 14d
in the coating are, effectively, gas-impermeable, depressions and
relaxations of depressions which occur in the overlay, for example
as a person supported on the overlay moves from time to time,
recurrently create the just-above-mentioned kind of bellows
air-flow effect within the inside of the overlay, forcing air to
flow inwardly and outwardly through the gas-permeable (breathable)
band portion(s) 14C in the coating.
[0084] It is these, several air-management features of the
invention, promoted by relative thinness in the overall overlay, by
the mechanical bondedness which exists between the core expanse and
the coating, by the coating structure, and by the
pre-compression/pretension conditions extant in the core expanse
and coating, respectively, which cause the overlay to adapt needed
anatomical-support airflow, and associated heat removal and
perspiration-management, in a manner whereby those supported areas
of the anatomy which should receive enhanced, cooling airflow in
the context of being protected against "decubitus onset" do receive
such enhanced treatment. This adaptation behavior is dynamic, in
the sense that changes in supported anatomy position are followed
appropriately and instantly in the context of most-needed airflow
availability.
[0085] We have also discovered that the thicker, outer coating
sublayers in the overlay, on one of which a supported user will
always be lying, aid in heat removal--transferring excess heat to
the interior of the overlay, wherein air flow functions to
discharge it laterally outwardly through the edges of the overlay.
These same outer, thicker sublayers play an important role in
minimizing friction and shear engagements with the anatomy of a
supported person. Such engagements are also naturally minimized by
the presence of any fabric which may be interposed the overlay a
supported anatomy, as well as by the fact that the outer surface of
coating layer 14d does not have a tendency to stick to the
skin.
[0086] Prior art structures that are known to us have no such
capabilities for offering this important
decubitus-injury-minimizing behavior. In many instances,
unfortunately, prior art structures often respond to support
indentation in a harmful manner which closes off support-offering
airflow capability the deeper/larger the indentation which
exists.
[0087] Regarding a certain aspect of moisture management, the
moisture-impervious character of the thicker, outer broad-area and
lateral-edge sublayers in the coating tend to inhibit external
moisture entry into the core expanse, including, importantly, along
the lateral margins of the overlay.
[0088] The overlay embodiment which has been described so far
herein has been found to perform very satisfactorily in many
applications and situations, but there are certain environments in
which it has been determined to be important that the overlay
furnish an even greater control over respiration-window access to
the central core structure, particularly to minimize, as close to
zero as possible, the likelihood that body fluids from a person
resting on the overlay might work their way through the respiration
window structure into the 100% open-cell foam core expanse.
[0089] Accordingly, while the overlay configuration pictured
specifically in FIGS. 1-3, inclusive, affords generally adequate
fluid-flow, and particularly liquid-flow baffling to prevent such
liquid seepage/leakage into the core expanse, another important and
preferred embodiment of the invention, now to be described, more
definitively controls the prevention of such an event, i.e., liquid
leakage. This alternative embodiment, which offers the most robust
"anti-leakage" control is illustrated in FIGS. 5 and 6 in the
drawings, to which attention is now specifically directed.
[0090] Indicated generally at 30 in FIG. 5 is a mattress overlay
which is constructed in accordance with the features of the
alternative embodiment of the present invention just mentioned
above, and now to be described. Overlay 30, which possesses a long,
central axis 30A, is pictured in a condition wherein it is
supported on a conventional hospital-bed mattress shown
fragmentarily at 31.
[0091] In many ways, overlay 30 is substantially the same in
construction (sizes, i.e., dimensions, and materials) as previously
described overlay 10, with the exception that, while its core
structure is essentially identical, and its coating-structure
layer-arrangement is also essentially identical, its
coating-provided respiration window structure, in terms of size,
location, and fluid-flow-control baffling, is quite different.
[0092] Continuing, included in overlay 30 is a core expanse 32
having (as was just mentioned) the same material construction,
dimensionality, and functional features as those described for
previously discussed core expanse 12. Core expanse 32, also
referred to both as a core structure and as a core, is coated by a
multi-layer/sublayer coating, or coating structure, 34 which, in
terms of its specific layer arrangement, its layer formation by
spraying, and its layer dimensionality, is identical (as was also
just mentioned) to previously described coating, or coating
structure, 14.
[0093] Because of the substantial structural identities just
mentioned between the two core expanses, and between the
layer/sublayer arrangements in their respectively associated
coating structures, we do not repeat here any detailed descriptions
of these structures--focusing attention instead on how coating
structure 34 in modified overlay 30 is specifically configured
differently to create the different form of overlay-end-disposed
respiration window structure mentioned generally above.
[0094] What specifically distinguishes the comparative
constructions of overlays 10 and 30 is that, whereas in overlay 10,
the included, baffled respiration window structure takes the form,
effectively, of an endless, elongate, thin-coating-region band
extending perimetrally around the outside of the overlay, as
described above, the baffled respiration window structure in
overlay 30 takes the form of a pair of relatively small,
rectangular windows, such as the window seen at 36 in FIG. 5, one
each formed adjacent the opposite, long-dimension ends of the
overlay. Because of the fragmentary nature of what is shown in FIG.
5, only one of these two windows is pictured in the drawings.
Window 30, and its counterpart located adjacent the opposite (and
unseen) end of overlay 30, is basically defined as a rectangle (as
mentioned) formed in the outer, thicker layer, of coating 34, with
the coating-layer edges that define this rectangular window
furnishing a portion of the lateral baffling which exists for each
of these windows. These windows herein have lateral dimensions of
about 1-inch by about 1.75-inches.
[0095] The adjacent, thicker and thinner regions in coating 34
which define window 36 are similar to what is illustrated in
enlarged, cross-sectional detail in FIGS. 2 and 3 for the adjacent,
thicker and thinner regions in coating 14, and these two FIGS. 2
and 3), accordingly, may correctly be viewed as furnishing a
closer, and more detailed, "picture" of the structure of window 36
than that which is presented for it more generally, and distantly,
in FIG. 5.
[0096] While different specific dimensionality may be chosen for
the windows, such as for window 36, a particular dimensional ratio
in overlay 30 has been determined as one which furnishes very
satisfactory respiration breathability for the core expanse in the
overlay, while at the same time minimizing overall window size to
inhibit the likelihood of liquid leakage into core 32 should any
such leakage liquid get past the foam filter blocks. This ratio
relates the surface area of one broad side of the overlay to the
combined areas of the two windows, such as window 36. More
specifically, in accordance with this special ratio, where the
overall surface area of a single broad side of the overlay is given
by the variable A, the combined surface areas of the two windows,
should equals about 0.0013 A.
[0097] Focusing attention now specifically on the region in overlay
30 which is immediately adjacent respiration window 36 as seen in
FIG. 5, directly, structurally and functionally associated with
this window is important, additional baffling structure, referred
to also herein as tell-tale-functioning, sacrificial baffling
structure, which takes the form of a baffling assembly 38. Assembly
38 includes a pair of laterally spaced, breathable, foam filter
blocks 40, referred to herein as baffle-filter blocks, disposed
slightly spaced from, but positioned generally relatively closely
adjacent, the laterally opposite sides of window 36. These blocks,
which have nominal (i.e., before an assembly 38 is installed, as
will shortly be explained) rectilinear configurations with
dimensions of about 1.times.1.times. 1/2-inches, are held in place
in the overlay by an expanse of transparent, moisture- and
gas-impervious adhering tape 42 having an adhesive side which
attaches to the two foam blocks, and to the clearly illustrated
surface regions adjacent window 36 on the opposite broad surfaces
of coating 34. As will also shortly be explained, attachment of the
baffling assembly to coating 34 to have the appearance seen in FIG.
5 produces the outwardly projecting, dome-like "rounding", or
out-of-rectangularity distortion, in those sides of the blocks
which generally face the viewer in FIG. 5.
[0098] Blocks 40 and tape 42 collaborate to form the entirety of
assembly 38, and collectively define an enclosed, moisture-passage
barriering, but gas-respiration-breathable, baffle chamber 44
disposed in communication with, and on the outside of, window 36.
As can be seen in FIG. 5, baffle chamber 44 is defined, on its
laterally opposite sides, by blocks 40, on its inner side by the
overlay edges of coating 34 which lie between these blocks and
which include window 36, and on its outer side, which faces
generally toward the viewer in FIG. 5, by tape 42.
[0099] This same kind of baffling assembly is present (though not
seen in the drawings) adjacent the other, end-disposed respiration
window structure in the overlay. Preferably, though not
necessarily, the two respiration window structures, such as window
structure 36, and the two, associated baffling assemblies, such as
assembly 38, are positioned somewhat to one side of the
longitudinal centerline, 30A, of the overlay to avoid any damage to
these structures in the event that the overlay is folded along this
centerline for storage, or for any other reason. This positioning
condition can clearly be seen for these structures in FIG. 5.
[0100] Preferably, the foam filter blocks are formed of the same
material which is employed in core expanse 32, and the adhering
tape is formed of 3M #8672 8-mil vinyl tape made by the 3M
Corporation. Also preferable is that the color of the specific foam
material employed in blocks 40 be light in color (such as white or
off-white), so that these blocks will function, via discoloration
which will be visible through the adhering tape, as "tell-tales" to
signal the occurrence of any liquid leakage which may be attempting
to reach the margins of the baffled respiration window.
[0101] FIG. 6 in the drawings illustrates, as mentioned above in
the description of this figure, a pre-shaping, pre-installation
preparedness condition for baffling assembly 38. Here, what can be
seen is that a piece of appropriately sized tape 42, with its
adhesive side appropriately exposed and upwardly facing in this
figure, has placed upon it, near a pair of its lateral margins, as
illustrated, and with the dispositions pictured, two, foam, baffle
filter blocks 40, each of which, as was also mentioned earlier
herein, nominally has a rectilinear block shape. Also placed upon
it, in order to cover the tape's adhesive surface which would
otherwise be openly exposed in the rectangular zone residing
between blocks 40, is a thin, transparent-material film 45 (shown
only fragmentarily). Film 45 prevents this zone in the tape from
inadvertently attaching itself to the portions of the outer coating
in the overlay that are exposed within baffle chamber 44 in a
manner which might partially, or completely, seal window 36.
[0102] With this pre-installation condition established, the
assembly is suitably curled, as indicated by arrows 46, 48, and
placed appropriately in juxtaposition to one of windows 36, with
suitable tension introduced into tape 42 in the installation
process to compress and reform the filter blocks so that they take
on the outwardly projecting domed shapes which are pictured clearly
for them in FIG. 5.
[0103] The adhesive material which forms part of tape 42 is
"non-damaging" in relation to coating 34, and as a consequence,
this allows a baffling assembly, in its "sacrificial" mode of
operation, namely, once there may be indicated a fluid leak which
has discolored one or both of the filter blocks, easily to be
removed for replacement by another, similar, baffling assembly.
Transparency in tape 42 easily enables one to see, by a looking for
discoloration in the preferably lightly colored filter blocks, any
indication that an undesired liquid leak has taken place, or has
begun.
[0104] Where it is desired that the overlay of the present
invention be employed with a person whose weight lies in the range,
for example, of about 350-lbs to about 500-lbs, two different
handling approaches, generally mentioned earlier herein, may be
employed. In one, a suitable, independent, bariatric, under-support
structure may be used. Preferably, such an under-support structure
will have essentially the same perimetral outline as that of the
supported overlay, and will furnish appropriate yieldable
under-support to prevent bottoming out of the core expanse in the
supported overlay. While many different kinds of such bariatric
under-support structures may be employed, we have experimented
successfully with a 1-inches thick pad formed of two layers of
different, rate-sensitive, viscoelastic foam materials specifically
made by AEARO Specialty Composites in Indianapolis, Ind., with an
upper layer in this pad having a thickness of about 0.75-inches and
being formed of the material sold as Confor CF-42 foam, joined by
adhesive bonding to a lower layer of the material sold as Confor
CF-45 foam having a thickness of about 0.25-inches. There are, of
course, many other materials which may be employed successfully for
such a bariatric under-support structure.
[0105] Another approach is illustrated in FIG. 7 in the drawings
generally at 50 which pictures another modified version of the
overlay of the present invention. Overlay 50, as proposed herein,
includes an overall thickness of about 2-inches, and is formed with
a plural-layer core, or core structure, 52 formed with a 1/2-inches
thick underlayer 54 of the above-mentioned Confor CF-45 foam
material, suitably adhesively bonded to an intermediate layer 56 of
the above-mentioned Confor CF-42 foam material, also having a
thickness of about 1/2-inches, and with layer 56 being suitably
adhesively bonded to a layer 58 having a thickness of about
1-inches, formed of same core-expanse material previously described
herein for expanses 12, 32.
[0106] Overlay 50 further includes an overall coating 60, which is
substantially identical in layer arrangement to the coatings which
have already been discussed herein. Coating 60 includes a pair of
baffle-chambered respiration windows (not specifically shown) which
are like those that have been described for the invention
embodiment of FIGS. 5 and 6, such respiration windows essentially
being formed so as to expose only core layer 60, generally at
opposite ends of overlay 50, and occupying regions generally
illustrated at W in FIG. 7.
[0107] Thus the present invention, now described in several
preferred embodiments, offers an anatomical pressure-evenizing
mattress overlay including (1) a core, in different-modification
forms, with each modification form possessing a dynamic-response
core expanse having spaced, upper and lower, surfaces and a
perimetral edge extending between these surfaces, the core expanse
being formed from a 100% open-cell, compressible and flowable,
viscoelastic foam, and having a relaxed-state volume in the overlay
which is prestressed, and about 8-10% compressed, thus to create a
pre-compression condition in the expanse, and (2) an elastomeric,
moisture- and gas-flow-managing, specially baffled,
respiration-windowed, coating, load-transmissively bonded to the
entirety of the outside of the core expanse to function as a
dynamically-responsive unit with the expanse, and possessing a
relaxed-state internal prestressed tension condition.
[0108] Within this structure, the core expanse exhibits a
compressive-deflection vs. compression-force curve which includes
an extremely linear region over which a relatively wide change in
compressive deflection is accompanied by an anatomically
insignificant change in compression pressure.
[0109] Accordingly, a unique mattress overlay structure which is
aimed with a very particular focus on helping to resolve the
decubitus ulcer/injury problem have thus been illustrated and
described herein, with certain variations and modifications
suggested. Among the important factors relating to resolving this
very dangerous and widespread kind of injury, namely, (a) paying
close attention to furnishing support for the anatomy with an
overall, evenized pressure which falls within a certain, identified
range of pressures, (b) controlling and minimizing friction and
shear conditions in the interface between the overlay support
structure and the anatomy, and (c), extremely importantly,
furnishing adequate cooling airflow to the supported anatomy via
respiration window structure which is specially baffled to control
both air(gas)-flow, and liquid-leakage, all are dealt with
effectively by the present invention.
[0110] As has been pointed out with great particularity, the unique
structure of the present mattress overlay includes a special core
foam material which is completely 100% open-celled in nature, and
which is nominally under compression, coated by a
differential-thickness, moisture- and gas-managing elastomeric
layer which is bonded tenaciously (interfacially, mechanically
bonded) to surface areas of such core foam. This unique
collaborative union of structures results in the occurrence of a
very special performance regarding anatomically-cooling airflow,
wherein the deeper the indentation produced in the overlay by a
portion of the body supported on it, the greater the "effective
openness" of the supporting core foam material to enhance airflow
in the region, or regions, of such indentation, or
indentations.
[0111] In conclusion, while a preferred and best mode embodiment
of, and manner of practicing, the present invention have been
illustrated and described herein, and certain variations and
modifications suggested, we appreciate that other variations and
modifications may be made without departing from the spirit of the
invention, and it is our intention that all of the claims to
invention will be construed as covering all such other variations
and modifications.
* * * * *