U.S. patent application number 10/405290 was filed with the patent office on 2004-01-15 for therapeutic limb covering using hydrostatic pressure.
Invention is credited to Kuiper, Hendrik Klaas, Reed, Bobby E..
Application Number | 20040010212 10/405290 |
Document ID | / |
Family ID | 28673680 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040010212 |
Kind Code |
A1 |
Kuiper, Hendrik Klaas ; et
al. |
January 15, 2004 |
Therapeutic limb covering using hydrostatic pressure
Abstract
The present invention provides a therapeutic limb covering and
an associated method of treating chronic swelling of a limb. The
limb covering is uses hydrostatic pressure provided by liquid
contained within the covering to apply pressure to the limb. The
limb covering comprises a substantially non-distensible flexible
outer layer, a distensible flexible inner layer joined together and
a liquid tight bladder therebetween. The covering may be adapted
for releasable securement about a limb such as an arm or a lower
leg and foot of a patient. After placement on the limb, when the
bladder is filled with a liquid, such as water, it expands to
contact and apply pressure to the limb.
Inventors: |
Kuiper, Hendrik Klaas;
(Edwards, MS) ; Reed, Bobby E.; (Vicksburg,
MS) |
Correspondence
Address: |
KIRKPATRICK & LOCKHART LLP
75 STATE STREET
BOSTON
MA
02109-1808
US
|
Family ID: |
28673680 |
Appl. No.: |
10/405290 |
Filed: |
March 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10405290 |
Mar 28, 2003 |
|
|
|
10114103 |
Apr 1, 2002 |
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Current U.S.
Class: |
601/152 ;
602/13 |
Current CPC
Class: |
A61F 5/0104 20130101;
Y10S 128/20 20130101; A61H 9/0078 20130101; Y10S 2/911 20130101;
A61F 5/012 20130101 |
Class at
Publication: |
601/152 ;
602/13 |
International
Class: |
A61H 023/00 |
Claims
1. A therapeutic limb covering configured to be placed over a lower
leg and foot of a patient comprising: a flexible, substantially
non-distensible outer layer; a flexible, distensible inner layer
joined to the outer layer; a liquid tight bladder defined between
the layers; at least one structural support member secured to a
layer to provide longitudinal support to the covering; a flexible
tongue portion, at least a portion of which being movable relative
to the inner and outer layers and configured to lie along the
instep and shin of a user.
2. A therapeutic limb covering as defined in claim 1 wherein at
least a portion of the tongue is formed from flexible liquid tight
inner and outer layers defining a liquid tight bladder
therebetween.
3. A therapeutic limb covering as defined in claim 1 wherein the
tongue portion is removable from and releasably securable to the
limb covering.
4. A therapeutic limb covering as defined in claim 1 wherein the
tongue is formed having a preset curve to accommodate an angled
orientation between the instep of the foot and the shin of the leg
over which the tongue lies.
5. A method of treating chronic swelling in a limb by applying a
therapeutic limb covering comprising: providing a limb covering
having a flexible non-distensible outer layer; a distensible inner
layer, a liquid tight bladder defined therebetween and a flexible
tongue portion releasably securable to one of the layers; placing
the tongue portion over the instep and shin; placing the limb
covering on the foot and leg of the user; securing the limb
covering about the limb; securing the tongue portion to the limb
covering; adding liquid to the bladder of the limb covering to at
least a sufficient level to establish a liquid column that applies
pressure to the limb.
6. A method of treating chronic swelling in the limb as defined in
claim 5 wherein: the tongue portion comprises inner and outer
layers with a liquid tight bladder defined therebetween; and the
method further comprises filling the bladder of the tongue portion
with a liquid.
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part of application
Ser. No. 10/1 14,103, filed Apr. 1, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to devices and methods for the
treatment of chronic swelling.
BACKGROUND OF THE INVENTION
[0003] Chronic swelling of a limb is a medical condition that
results in pain, tissue breakdown and immobility for many patients.
Such swelling is often caused by venous insufficiency or other
disease such as lymphedema. In the case of venous insufficiency or
venous stasis, the venous system of the extremities, particularly
the lower extremities, experiences reduced blood flow. The reduced
blood flow results from venous dysfunction in the extremity that
limits the effective return of blood from the extremity back to the
heart. The problem is exacerbated in lower extremities due to the
effect of gravity, which must be overcome to move the blood back to
the heart. However the arms are also susceptible to chronic
swelling conditions such as may be caused by cancer of the lymph
glands or post-mastectomy radiation treatment.
[0004] A common treatment for chronic swelling is the application
of external pressure to increase tissue pressure in the region.
This treatment decreases the swelling and improves tissue
oxygenation, thereby allowing tissue to heal. In applying pressure
to the leg, it is desirable to apply the highest pressure at the
ankle and gradually decrease the pressure that is applied toward
the top of the lower leg. However applying pressure to the limb can
be problematic for a patient that also suffers from poor arterial
perfusion. Poor arterial perfusion is caused by insufficient blood
supply and blood has difficulty reaching the limb, not just
returning from the limb as with venous insufficiency. Applying
pressure to the limb serves to help prevent blood from ever
reaching the limb. Therefore, traditional methods of treating
chronic swelling cannot be used for patients with poor arterial
perfusion.
[0005] A known means for applying pressure to the limb to treat
chronic swelling is highly elastic bandages or multiple wrappings
(in the case of devices for the foot and leg). The wrapping is
wrapped tightly around the limb to apply pressure for the purpose
described above. The wrappings generally must be applied by a
caregiver. After initial treatment, elastic stockings are used by
the patient to continue preventative treatment. The stockings do
not need to be wrapped about the limb, however, they must be
stretched over the limb, including the foot, ankle and calf in
order to be donned. A disadvantage of these devices is that they
are difficult for a user, particularly an elderly or disabled user,
to stretch onto the limb for suitable therapeutic benefit. Also,
the wrappings and elastic stockings constantly apply pressure to
the limb when they are worn without a mechanism for selectively
discontinuing the pressure they apply. Thus patients that also
suffer from poor arterial perfusion cannot use the wrappings and
stockings because there is no way for them to periodically
discontinue the pressure to allow blood to flow to the limb.
[0006] Another approach to treatment of chronic swelling has been
to apply pressure to the limb with a fluid. An advantage of using a
fluid to apply pressure is that it readily conforms to the unique
contours of a limb and can be applied easily by a user. U.S. Pat.
Nos. 4,805,601 (Eischen) and 5,711,760 (Ibrahim et al.) disclose
lower limb coverings having air bladders for applying pneumatic
pressure to the limb. Other pressure applying devices use the
pressure applied by a liquid surrounding the limb. U.S. Pat. No.
3,977,396 (Cartier) discloses an apparatus using liquid pressure,
which comprises a tub filled with liquid mercury into which the
patient places the limb surrounded by an impervious flexible
wrapping to prevent contact with the mercury. The pressure applied
by the liquid mercury around the surfaces of the submerged limb is
believed to provide treatment for the chronic swelling condition of
the limb.
[0007] Another treatment device described in U.S. Pat. No.
5,759,164 (Pacey) uses hydrostatic pressure applied to the limb by
a liquid tight bag wrapped around the limb and filled with liquid.
The flexible bag is filled with liquid to apply pressure to the
limb by a separate liquid reservoir that is attached to the body
above the limb and joined to the bag by a conduit
SUMMARY OF THE INVENTION
[0008] The present invention provides a therapeutic limb covering
that uses hydrostatic pressure applied to a limb to treat chronic
swelling. The limb covering comprises a flexible, substantially
non-distensible outer layer and joined to a flexible, distensible
inner layer and defining a liquid tight bladder therebetween. The
bladder defined between the layers is filled with liquid, such as
water, to create the hydrostatic pressure that is applied to the
limb when the covering is worn.
[0009] The covering is shaped to fit relatively closely to the
limb. For example, in a device intended for the lower leg and foot,
the covering is configured similar to a boot having a foot portion
and a calf portion extending substantially perpendicular to the
foot portion. However, the device alternatively may be configured
to fit about an arm. The covering circumferentially surrounds the
limb to apply pressure to a substantial portion of the limb
surface. The covering may have a securable opening, secured by
means such as Velcro.RTM. hook and loop fasteners to facilitate
donning by the patient. Velcro.RTM. fasteners provide for a wide
range of size adjustability useful for fitting different sized
limbs. Alternatively, the opening may be secured by a zipper or
other means such as snaps, buckles or ties. With such fasteners,
size adjusters, such as Velcro.RTM. hook and loop fasteners straps,
may additionally be employed on the limb covering to take up slack
between the covering and the limb to achieve a snug, but not tight,
fit with the limb. Regardless of the fastening means used,
adjustability for a snug fit permits a single limb covering size to
properly fit a range of limb sizes. Additionally, achieving a snug
fit reduces the amount of liquid that is needed to in the bladder
to apply the necessary hydrostatic pressure to effectively counter
the chronic swelling. Reducing the amount of liquid required to use
the limb covering reduces the weight of the covering, which is
important in maintaining the mobility of the patient.
[0010] In one aspect of the invention the limb covering is
configured to include one or more structural supports to help
maintain axial fortitude of the covering and promote uniform
coverage of the device over the limb. The support may be joined to
the outer layer of the covering for at least a portion of its
expanse. Column strength of the covering material is important to
prevent collapse of the covering under the weight of the liquid
contained in the bladder. Resistance to collapse ensures that the
covering retains the intended coverage area of the limb and the
appropriate column height of the liquid. However, the structural
support should be configured to permit some lateral flexibility to
permit movement of the limb and mobility of the patient.
[0011] In one embodiment of the covering, the structural support
comprises a layer of semi-rigid material such as polymer
closed-cell foam. The structural layer of foam is secured to the
outer layer and extends over a substantial portion of its inner or
outer surface to provide longitudinal consistent compressive
strength throughout the structure to maintain the form of the
covering. In addition to the benefit in strength, the foam
structural layer provides other desirable properties to the boot
additional to its performance as a structural support. First, the
foam layer provides insulation from physical shock to the limb,
such as may occur if a fixed object is bumped by the limb during
movement. If a shock is experienced by the limb, the foam layer
provides some padding to cushion the impact. The foam layer also
provides some thermal insulation to the limb. The cell structure of
the foam serves to reduce heat loss through the layer thereby
helping to keep warm the limb wrapped by the covering. The thermal
insulative effect of the foam, in conjunction with a reduction of
evaporation when polymer layers are used for the wrapping, may tend
to promote healing of any wounds present on the limb while the
device is worn. Additionally, the liquid used to fill the bladder
can be warmed to any comfortable temperature to warm the limb and
the liquid jacket further serves to help prevent heat loss. The
liquid jacket also helps to protect the limb from shock, absorbing
impacts with other objects.
[0012] In another aspect of the invention the covering is
configured such that the bladder extends through the boot-type
covering from the underside of the foot to at least the mid-portion
of the calf. The arrangement of the bladder under the foot causes
alternating compression and release of the bladder during
ambulation of the patient. Each compression of the bladder creates
a sudden increase in pressure transmitted as a wave throughout the
bladder in the liquid contained therein. The wave transmitted
through the liquid creates circulation of the liquid in the
bladder. The pressure wave causes movement of the bladder wall
against the limb surface that mimics the calf muscle pump to urge
movement of blood or collected fluids upward from the limb.
[0013] In some embodiments of the boot-type covering, a tongue
portion additionally may be provided to improve comfort to the
wearer and to more efficiently transmit hydrodynamic pressure to
the surface of the limb. The tongue may be configured similar to a
tongue portion of a conventional shoe or boot, movable relative to
the body of the boot-type covering and extending along the opening
of the boot to contact the instep (top surface) of the foot and the
shin of the user. The tongue lies against the limb with the opening
of the boot secured over it. The tongue serves to fill any gaps
that may exist at the interface of the two edges of the opening
when they are secured in overlapping fashion about the limb.
[0014] The tongue may be permanently joined to the boot or made
entirely separable from the boot and attachable by releasable means
such as hook and loop fasteners. The tongue maybe joined in a
hinged arrangement to the covering at the end of the foot portion
adjacent the toe opening. If made completely separable, the tongue
may be attached at its ends to the donned boot by any releasable
securement means to end of the foot portion and top of the calf
portion. The tongue should be soft and pliable may include a liquid
filled bladder to provide adjustable hydrostatic pressure to the
limb in similar fashion to the main body of the boot-type device.
If configured to have a bladder, the tongue may be formed of
flexible, elastic layers of a material such as urethane with the
liquid bladder defined therebetween. The tongue may be formed to
have a set curvature along its length that follows the shape of the
transition from the user's instep to shin areas.
[0015] The configuration of the covering uses the principle of
pressure exerted by a liquid column to the therapeutic benefit of
the limb experiencing chronic swelling. The column of liquid
maintained around the limb by the covering provides hydrostatic
pressure directed inwardly toward the limb that increases linearly
from the upper portion of the limb covering downward to the bottom
portion of the covering. Due to the effect of gravity, the amount
of pressure exerted by liquid in the bladder at any given point is
dependent on the height of the liquid above that point. In the
example of a covering configured as a boot to cover the foot and
lower leg, the liquid column maintained therein applies the
greatest outward pressure at the lowest region of the boot, which
corresponds to the foot, ankle and lower calf. As the boot extends
upward on the calf, pressure exerted by the liquid decreases
linearly due to the influence of gravity on the liquid column.
However, if needed, pressure applied by the limb covering can be
increased beyond what is provided solely by the force of liquid
maintained in a column around the limb. A "pre-charge" pressure can
be created in the limb covering to increase the magnitude of
pressure that is applied by the liquid column at every point across
the limb. The pressure can be increased by increasing the amount of
liquid transferred into the bladder to increase pressure above that
which would be exerted by hydrostatic pressure alone. The
pre-charge pressure also can be created by reducing the available
volume of the covering by tightening its fit around the limb after
it has be filled and the port sealed.
[0016] The pressure properties of the liquid column maintained by
the covering correspond to the therapeutic requirements of the
limb. The lowest portion of the limb requires the greatest pressure
from the covering due to the influence of gravity on the blood in
the venous network that is not returning properly to the heart.
Consequently, for effective treatment, higher pressure should be
applied to the limb in lower regions to counter the increased
swelling that occurs there.
[0017] The limb covering according to the present invention
exhibits theses desirable performance characteristics naturally due
to the pressure distribution exhibited by a liquid column. When a
limb with the therapeutic covering is maintained such that the
longitudinal axis of the limb is maintained vertically, the liquid
column applies greater pressure at the lower regions of the limb
where it is most needed. For example, in the case of a boot
covering, the longitudinal axis of the limb is considered to be
oriented vertically when the longitudinal axis of the calf is
vertical, such as when standing. However, pressure around the lower
region of the limb can be easily discontinued by elevating the limb
so that the longitudinal axis this placed in a horizontal position.
In the horizontal position, most of the liquid column is no longer
above the lower region of the limb and pressure is greatly reduced.
This capability of the limb covering makes it suitable for use by
patients with poor arterial perfusion. Those patients are able to
discontinue pressure applied by the covering from time to time
simply by elevating their limb to a horizontal position.
[0018] It is an objective of the present invention to provide a
therapeutic limb covering that is lightweight and easily donned and
used by a patient.
[0019] It is another object of the invention to provide therapeutic
limb covering that provides hydrostatic pressure against the
surface of the limb to provide therapeutic benefit to the limb.
[0020] It is another object of the invention to provide a
therapeutic limb covering that comprises a substantially
non-distensible outer layer, a distensible inner layer and a liquid
tight bladder between them.
[0021] It is another object of the invention to provide a
therapeutic limb covering that comprises a substantially inelastic
shell joined to an elastic double-walled bladder.
[0022] It is another object to provide therapeutic limb covering
that comprises a bladder that extends under the foot and upward
along the calf so that ambulation tends to compress the bladder to
create alternating pressurization of the bladder.
[0023] It is another object of the invention to provide a
therapeutic limb covering using hydrostatic pressure that employs
at least one structural support to help maintain the shape and form
of the covering.
[0024] It is another object of the invention to provide a
therapeutic limb covering that provides thermal and shock
insulation to the limb it covers.
[0025] It is another object of the invention to provide a
therapeutic limb covering that is configured to fit a wide range of
limb sizes.
[0026] It is another object of the invention to provide a method of
treating chronic swelling using hydrostatic pressure.
[0027] It is another object of the present invention to provide a
therapeutic limb covering to treat chronic swelling that also can
be safely used by patients with poor arterial perfusion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The foregoing and other objects and advantages of the
invention will be appreciated more fully from the following further
description thereof, with reference to the accompanying
diagrammatic drawings wherein:
[0029] FIG. 1 is a side view of a therapeutic limb covering;
[0030] FIG. 2 is a front view of a therapeutic limb covering;
[0031] FIG. 3 is a sectional view of the therapeutic limb covering
of FIG. 1 taken along the section line 3-3 of FIG. 1;
[0032] FIG. 4 is an illustration of a therapeutic limb covering
being worn about the lower leg and foot of a user showing movement
of liquid contained in the covering;
[0033] FIG. 5 is a sectional side view of a therapeutic limb
covering;
[0034] FIG. 5A is a detail of area A of FIG. 5;
[0035] FIG. 6 is a top view of a pattern for the therapeutic limb
covering;
[0036] FIG. 7 is a transparent side view of a therapeutic limb
covering with a side mounted securement mechanism;
[0037] FIG. 8 is a front view of an embodiment of the therapeutic
limb covering in an open configuration;
[0038] FIG. 9 is a front, isometric view of an embodiment of the
therapeutic limb covering in a closed configuration;
[0039] FIG. 10 is a sectional top view of an embodiment of the
therapeutic limb covering taken along the line 10-10 of FIG. 9;
[0040] FIG. 10A is a detailed view of the opening area of the
therapeutic limb covering as shown in FIG. 10;
[0041] FIG. 11 is a detailed view of the arrangement of layers in
the therapeutic covering;
[0042] FIG. 12 is an illustration of a pattern for the bladder and
shell of the therapeutic covering;
[0043] FIG. 13 is an illustration of a pattern for a single piece
structural support;
[0044] FIG. 13A is an illustration of a pattern for a sole insert
of the therapeutic covering;
[0045] FIG. 14 is an illustration of the several patterns assembled
together;
[0046] FIGS. 15A and 15B are top view illustrations of the sole
portion of the therapeutic limb covering;
[0047] FIG. 16 is a sectional view of the foot portion of the
therapeutic limb covering taken along the line 16-16 of FIG. 9;
[0048] FIGS. 17 and 18 are side view, illustrations of the
therapeutic limb covering showing liquid flow through the
bladder;
[0049] FIG. 19 is a front view of the tongue type therapeutic limb
covering in an open configuration;
[0050] FIGS. 19A and 19B are top views of the front and back of a
removable strap;
[0051] FIG. 20 is a front, isometric view of the tongue type
therapeutic limb covering in a closed configuration;
[0052] FIG. 21A is a front view of a tongue component of the
therapeutic limb covering;
[0053] FIG. 21B is a side view of a tongue component of the
therapeutic limb covering;
[0054] FIG. 22 is an illustration of a pattern for a boot-type limb
covering showing placement of a removable strap;
[0055] FIG. 23 is a sectional top view of the tongue-type
embodiment of the therapeutic limb covering taken along the line
23-23 of FIG. 20;
[0056] FIG. 24 is a sectional top view of the tongue-type
embodiment of the therapeutic limb covering taken along the line
24-24 of FIG. 20;
[0057] FIG. 25 is a sectional top view of the tongue-type
embodiment of the therapeutic limb covering taken along the line
25-25 of FIG. 20;
[0058] FIG. 26A is a sectional top view of the tongue-type
embodiment of the therapeutic limb covering taken along the line
25-25 of FIG. 20 showing the comparative magnitude of hydrodynamic
forces;
[0059] FIG. 26B is a graphical representation of the increase in
hydrodynamic force of liquid maintained in the therapeutic limb
covering as a function of height;
[0060] FIG. 27 is an illustration of a therapeutic limb covering
configured to be worn about an arm;
[0061] FIG. 27A is an illustration of a manual pump bulb area of a
therapeutic limb covering configured to be worn about an arm;
[0062] FIG. 28 is a diagrammatic illustration of components used in
the filling process for the limb covering using a syringe;
[0063] FIG. 29 is a diagrammatic illustration of the filling
process of the limb covering using the force of gravity;
[0064] FIG. 30 is a diagrammatic illustration of hydrostatic forces
applied to a limb while using the limb covering;
[0065] FIG. 30A is a diagrammatic illustration of hydrostatic
forces applied to a limb while using the limb covering that has
been pre-charged with additional liquid to achieve an over-fill
condition;
[0066] FIG. 31 is a diagrammatic illustration of hydrostatic forces
applied to a limb while using the limb covering in a horizontal
position;
[0067] FIG. 32 is a graph plotting hydrostatic pressure in terms of
skin contact pressure in millimeters of Hg versus water column
height in inches.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0068] FIGS. 1 and 2 show a therapeutic limb covering according to
the present invention. FIG. 1 shows a limb covering configured as a
boot 10 configured to fit about a patient's foot and lower leg. The
boot comprises a calf portion 12 and a foot portion 14. The
covering is donned about a patient's foot and lower leg such that
the toes protrude from toe opening 16, and the calf portion 12
extends up the lower leg such that calf opening 18 is positioned
just below a patient's knee 20 (as best seen in FIG. 4). The foot
portion 14 is oriented substantially perpendicular to the calf
portion 12 to mimic the orientation of the foot and leg under most
circumstances, but the entire covering is made from flexible
materials so that the orientation between the foot and leg remains
flexible and capable of movement.
[0069] FIG. 3 is a sectional view of the boot shown in FIG. 1 taken
along the line 3-3 of FIG. 1. The limb covering comprises a
flexible but substantially non-distensible outer layer 22 joined to
a flexible and distensible inner layer 24 to define a liquid tight
bladder 26 therebetween. The bladder is filled with any convenient
liquid, such as water, to apply pressure to the limb 19 about which
the covering is worn. It is noted that other suitable liquids may
have densities that are different than water to provide a different
resulting pressure such include salt water or gel substances.
[0070] The distensible inner layer is elastic and expands under the
pressure of the liquid in the bladder, while the inelastic outer
layer 22 retains the shape of the covering so that it remains
properly positioned around the limb. Liquid transfer valve 62,
bonded to the calf portion 12 and in liquid communication with the
bladder 26 provides sealable port through which liquid may be added
to or removed from the bladder.
[0071] The covering is provided with an opening 28 that is
releasably securable by means such as a zipper 30 so that the
covering may be opened to facilitate donning by the patient then
secured to place the covering close proximity to the surface of the
patient's limb. The opening may be located on the front of the calf
portion 12, longitudinally extending the length of the calf
portion. Alternatively, the opening 28 may be positioned elsewhere
on the calf, such as on the side of the calf portion 12, which is
shown in FIG. 7.
[0072] Additionally, as shown in FIG. 7 size adjusters 31 may be
employed at various locations on the covering to tighten or loosen
its fit about a limb and to accommodate a variety of limb sizes.
The size adjusters 31 may comprise easily securable means such as
Velcro straps, ties or buckles placed around the calf and/or foot
portions, capable of cinching the covering close to the limb after
the opening 28 is closed, if needed. The size adjusters make a
single size of limb covering useable for a variety of limb sizes.
Different sizes of limb coverings may need to be provided for
extreme size differences, but it is expected that approximately
three size ranges (small, medium and large) would be sufficient to
fit the majority of the adult population. Additionally the size
adjusters provide a means for adjusting the tightness of the
covering about the limb in order to control the volume of the
bladder. Tightening a limb covering that is already filled with
water will create an "over-fill condition" where the amount of
liquid in the bladder exceeds the available non-distended volume of
the bladder. That condition increases the magnitude of pressure
applied by the limb covering against the limb. Alternatively,
tightening an unfilled boot against the limb will reduce the amount
of liquid required to fill the bladder and establish the liquid
column about the limb, which reduces weight.
[0073] A dynamic feature of the boot limb covering is modulation of
the hydrostatic pressure that occurs during movement, which is
illustrated in FIG. 4. During ambulation, when the patient puts
weight on the limb 19, the foot 21 compresses the bladder 26,
reducing its volume and forcing liquid outward and upward from the
area. A sudden movement of liquid from beneath the foot 21 causes a
positive pressure wave that travels upward through the limb
covering as illustrated by pressure wave arrows 86. The upwardly
traveling pressure wave 86 externally mimics the pumping action of
muscles in the leg to provide an additional therapeutic benefit in
the treatment of chronic swelling of the limb. The pressure wave
modulates the hydrostatic pressure in the bladder, which serves to
distend the inner layer 24 in a wavelike fashion. That action of
the inner surface against the skin surface of the limb 19 urges
blood to flow up the leg to help treat chronic swelling of the
limb.
[0074] FIG. 5 shows a sectional view of a limb covering configured
as a boot 10 having outer and inner layers 22 and 24 and a bladder
26 defined between the layers. Area A is shown in detail in FIG. 5A
to illustrate the composition of the layers. The outer layer 22
should be flexible yet substantially non-distensible and liquid
tight. To achieve this combination of characteristics, the outer
layer may be comprised of an outer shell 32 to provide
inelasticity. Possible materials include GORE-TEX.RTM. fabric or
KEVLAR.RTM., nylon, polyester, denim, acetate or thick PVC,
neoprene or natural rubber.
[0075] If the material of the shell is not liquid tight, a liquid
tight backing 34 may be bonded to the inside surface 36 of the
shell 32. The backing is bonded to the inside surface 36 of the
shell to ensure that the shell will be impermeable to liquid
contained within the bladder 26. In FIG. 5A, the backing 34 is
shown separated from the shell 32 for illustration purposes only,
but it should be understood that the backing is bonded directly to
the shell at least at its outer peripheral edge 40 and preferably
across its entire surface. The backing may be any liquid tight
flexible material such as PVC of a thickness on the order of
approximately 6 mil, or other thicknesses necessary to handle
expected pressures. Also other materials such as polyurethane may
be used. It should be understood that bonding of the materials
together may be accomplished by means such as radiofrequency (RF)
welding, adhesive bonding, heat welding, ultra sonic welding,
stitching or any other suitable means of bonding the materials.
[0076] The inner layer 24 should be flexible, elastic and
distensible to communicate to the limb the pressure created by the
liquid. The inner layer may be constructed of a liquid tight, thin,
flexible bladder wall 38 that is bonded to outer layer 22 at least
around their peripheral edges 40, 41. The outside surface 42 of the
inner layer, which faces the limb, may contact the limb directly or
may be lined with a comfortable material liner 44 to contact the
patient's skin. The liner may be formed from any flexible material
that will not interfere with the elasticity of the bladder wall 38.
A possible liner material choice is polyester. The liner should be
bonded to at least the outer periphery 41 of the bladder wall but
may be bonded across selected portions or all of its surface area,
but should not degrade the distensibility of the bladder wall.
Alternatively, the comfortable material suggested for the liner 44
may be worn separately on the limb, such as a stocking, before
donning of the limb covering. The exemplary materials listed above
for layer construction of the therapeutic limb covering are
intended only to be illustrative and should not be considered to
limit the scope of the invention. Other suitable materials meeting
the objectives described for the inner and outer layers may be
used.
[0077] FIG. 6 shows an illustrative configuration for a pattern
from which the boot type therapeutic limb covering may be
constructed. FIG. 6 shows the inner layer 24 bonded on top of the
outer layer 22 prior to final bonding of the pattern edges to
create the finished boot. The inner layer 24 is bonded to the outer
layer 22 along their outer peripheries 40, 41. Additionally, the
inner layer 24 may be bonded to the outer layer 22 at selected
locations such as along surface seams 48 to help promote integrity
of the liquid bladder 26 that is defined between the inner and
outer layers 24 and 22. Surface seams 48 need only be a thin line
of bonding and may have circular termination points 50 to
distribute separation forces created by the liquid, thereby adding
to the integrity of the seam.
[0078] The foot region 14 of the boot is shown to have three trunk
portions 52 while the covering is in the flat sheet pattern form.
The trunk portions are bonded together to form the foot portion 14
shown in FIGS. 1 and 2. To join the trunk portions, two left foot
seams 54, two right foot seams 56 and two top seams 58 are bonded
to form a foot portion 14. The calf portion 12 of the boot is left
unbonded at calf seam 60 to provide an opening that will have
attached to it a securable closure device such as a zipper. All
bonds between the layers described in connection with the limb
covering may be created by known techniques for the given materials
such as RF welding, adhesive bonding or heat welding, ultrasonic
welding or stitching.
[0079] Also shown in FIG. 6, in phantom, is the liquid transfer
valve 62 joined to the calf portion 12 of the boot 10. The liquid
transfer valve permits liquid to be added or removed from the
bladder defined between inner and outer layers 24 and 22. The
liquid transfer valve protrudes from and is accessible from the
outer layer 22 but penetrates through the layer to be in fluid
communication with the bladder 26 (as shown in FIG. 5). The valve
62 is held in place through the outer layer by a valve flange 64
bonded to the backing 34 and inside surface 36 of the shell 32 to
be liquid tight. Inner valve mechanism 66 may be spring loaded to
be easily opened by the user by applying attachment pressure with a
liquid supply line to the valve's nipple 65. Removing the supply
line permits the spring-loaded valve to close and contain the
liquid. A suitable valve mechanism as described above, is known as
a luer-lock and is available from ARK-PLAS Products, Inc., Flippin,
Ark. An angled valve connector, part number 167ACU, available from
Halkey Roberts Corp., St. Petersburg, Fla., may also be used.
Alternatively, a conventional luer fitting with a manually
controlled valve may be used to permit exchange of liquid into the
bladder of the covering and to seal the liquid within the
bladder.
[0080] At least one structural support member 68 may be provided in
the calf portion 12 of the limb covering as shown in FIGS. 2 and 3.
The structural support members provide support to the covering, in
the calf region 12 so that the covering does not collapse under the
weight of liquid maintained in a vertical column against the leg.
Though the inelastic outer layer 22 provides support to keep the
shape of the covering when filled with liquid, the structural
support members provide additional fortitude to reduce the chance
of sagging and to help maintain the shape of the covering. The
structural support members should be axially stiff to provide
column strength to the covering yet be laterally flexible, to bend,
flex and conform to the leg during ambulation of the patient. Any
rigid lightweight polymer is a suitable material for the structural
members. Any number of members may be used. However, four to six
rectangular shaped members extending the majority of the length of
the calf region 12 of the boot 10 is believed to provide sufficient
support to the covering.
[0081] The structural support members may be joined to the inside
surface 36 of the outer shell 32 by bonding and may be covered by
the liquid proof backing 34 that is also bonded to the inside
surface 36 of the shell. As shown in FIGS. 2 and 3, the structural
supports should be positioned between surface seams 48, which serve
to join the inner layer 24 to the outer layer 22 along selected
regions. Because the structural support members are thin, light
weight and are joined to the outer layer 22, the patient does not
feel them and they do not interfere with filling of the bladder 26.
It is noted that other configurations for the structural support
members and mounting locations, including mounting on the exterior
surface of the outer layer 22, may be used.
[0082] In another configuration of the covering, structural support
may be provided to the covering by a single rigid member, bonded to
or incorporated into the outer layer, either internally or
externally. The single member may have a plurality of vertically
extending grooves to form a plurality of corresponding ribs
therebetween. The thicker material of the ribs helps to provide
column strength in the member and the covering. The grooves provide
lateral flexibility for bending of the covering during patient
movement.
[0083] Another embodiment of the limb covering is shown in FIGS. 8
and 9. The boot covering 110 is similar to the boot embodiment 10
discussed in connection with FIGS. 1-7 above, but employs several
alternate configurations that may be employed altogether as in the
example discussed here or may be employed individually in a
covering as desired by one practicing the invention. The covering
110 is similar in that it is formed from a substantially inelastic
outer layer 122 and an elastic inner layer 124 bonded together at
their peripheries to define a liquid tight bladder 126 between
them. The resulting covering can be formed into a shape to cover
the limb to be treated. In particular, the covering may be formed
as a boot 110 for the foot and lower leg, or may be formed as a
sleeve to be fitted over the arm as will be discussed below. In the
case of the boot, a calf portion 112 and foot portion 114 are
formed as well as corresponding calf and toe openings 118 and 116.
The boot 110 also has a securable opening 128 to facilitate donning
by a patient.
[0084] An alternate feature shown on boot 110 is the system for
securing the opening 128. A securement mechanism 130 may be
comprised solely of Velcro type closures rather than the zipper 30
of boot 10 shown in FIG. 1. A Velcro securement mechanism also
eliminates the need for additional, separate size adjuster
components described above in connection with boot 10. In the
alternate configuration shown in boot 110, Velcro hook portions 131
may be joined to several flap areas 127 formed along an edge 129 of
the opening 128. The hook portions may be joined to the outer layer
of the boot by bonding techniques known in the art such as
stitching or RF welding. A suitable hook fastener is the Hook 88
fastener, part number 184150 available from Velcro USA Inc,
Manchester, N.H. Corresponding Velcro loop portions (not shown) may
be fitted to the opposing edge 133 of the opening 128.
Alternatively, the outer layer 122 may comprise a shell 132 of a
material that provides a suitable napped surface with closed loops
capable of catching the Velcro hook portions. In this
configuration, the entire outer surface of the covering is
available to secure the Velcro hook portions thereby providing a
wide range of adjustability to accommodate different sized limbs.
Additionally, the napped texture of the outer shell provides a
comfortable feeling to the touch of the user. A suitable shell
material for serving as the loop portion fastener is an engageable
knit loop fabric such as part number S040 available from Highland
Industries Inc., Framingham, Massachusetts.
[0085] The several flaps 127 formed into the outer layer 122 of the
covering permit greater flexibility through the ankle area of the
foot when the covering is secured around a limb. The articulated
shape of the covering provided by the flaps reduces the amount of
excess material that may tend to bunch up and bulge when flexing
occurs at the ankle area. However, the triangle shaped flaps 127
still provides adequate coverage of the limb by the bladder 126
through the area of the ankle and foot as the bladder is shaped to
extend along the articulated flap, at least partially. When the
flaps 127 are wrapped around the limb and secured, substantial
coverage of the limb by the bladder extending along the flaps
occurs. The flaps are defined as cut-outs in the outer layer 122
and have rounded termination points 135 that reduce stresses on the
material that may lead to tearing during use.
[0086] Another alternate configuration as shown in the covering of
FIGS. 8 and 9 is a continuous, open bladder 126. The bladder 126 is
configured as an independent, double-walled continuous chamber,
without segmented areas or baffles as was defined by surface seams
48 in the therapeutic limb covering 10 embodiment shown in FIGS.
1-7. A continuous bonding seam 148 around the periphery 140 of the
bladder is present to join the two walls of the bladder together.
The bladder is bonded to the to the shell 132 of the outer layer
122 around the periphery 140 of the bladder at seam 148. The
several surface seams 48 of the previous embodiment are not
employed. The resulting bladder 126 provides a more continuous
contact with the limb 19 as is best shown in the cross-sectional
illustration of FIG. 10 taken along the line 10-10 of FIG. 9. As
compared with the same cross-sectional view of the previous
embodiment shown in FIG. 3, improved contact by the inner layer 124
with the limb 19 is promoted around the entire circumference of the
limb in the absence of surface seams 48. In FIG. 10, the only minor
discontinuity of contact between the inner layer 124 and the limb
19 occurs at the area of the opening 128, which is secured by
securement mechanism 130. At this juncture, the ends of the bladder
150, defined by periphery seams 148 define the only discontinuity
in contact of the bladder 126 with the limb 19. However, this
discontinuity is minimized by sizing the boot such that the bladder
end points 150 at least abut each other when the covering is
wrapped closed around the limb, as shown in FIG. 10. This
configuration should occur when the maximum sized limb is inserted
into a limb covering of a given size range. This size of limb
covering will also be able to accommodate smaller limb diameters as
the opening 128 can be overlapped, such that the bladder ends 150
overlap to make the closed diameter of the covering tighter to
achieve a snug fit about the smaller sized limb. The overlap
configuration of the secured limb covering is not shown in the
figures but should be readily recognized by those skilled in the
art. The more complete limb contact provided by the continuous
chamber 126 is believed to maximize the therapeutic benefit
provided by the covering. FIG. 10A shows in detail, the connection
interfaced between the opposing edges 129 and 133 of the opening
128 of the covering. It can be seen that the ends of the bladder
150 meet in abutment when the securement mechanism 130 of Velcro
hooks 131 is joined to shell 132 of the outer wall of the outer
layer of the covering.
[0087] Another alternative configuration incorporated into the
covering 110 is a single piece structural support member 168 (shown
in phantom in FIGS. 8 and 9) that is incorporated with the covering
as a layer, extending substantially coextensive with the shell 132
of the outer layer 122. The structural support member 168 is a
flexible, but semi-rigid material that provides longitudinal
compressive strength to prevent buckling of the covering under
weight of the liquid, yet it allows lateral flexibility for bending
of the limb. A suitable material for the single piece structural
support member 168 may be a polymer foam material, such as NBR/PBC
elastomeric foam, a closed cell foam material, available under the
trade name ENSOLITE.COPYRGT. available from Rubatex, Roanoke, Va. A
structural support layer 168 formed from such material may be on
the order of approximately 1/8" to 1/4" in thickness. As shown in
FIG. 8 and in FIGS. 11, 13 and 14 to be discussed in detail below,
the structural support 168 should extend over a substantial portion
of at least the calf portion 112 of the limb covering 110, which
will experience the majority of the compressive loading under the
weight of the liquid contained in the bladder while the covering is
in use. For example, as shown in the figures, the structural
support 168 may extend substantially coextensively with the shell
132 of the outer layer 122, down to the bottom of the calf portion
112, but need not extend into the foot portion 114. Rather, the
base of the structural support 168 may terminate near the sole 172
of the covering. An arch 169 may be formed in the structural
support around the top of the heel to permit flexibility of the
covering in this area and to reduce chaffing on the heel during
ambulation and to facilitate donning of a shoe over the device.
Additionally, an aperture 171 may be formed in the outer layer 122
at the heel to provide additional flexibility in the heel
region.
[0088] The structural support should be joined to the outer wall
122 of the covering to best provide support and strength for
maintaining the form of the covering when filled with liquid. The
support may be joined to the interior surface of the shell 132 of
the outer layer 122 and be covered by the bladder wall so as not to
be exposed to liquid contained in the bladder. The structural
support may be joined to the outer layer 122 by bonding at certain
points or across its entire surface to the shell 132.
Alternatively, the structural support may be captured in close
proximity to the shell 132 by the bladder wall that is bonded
around its periphery 140 to the shell 132. Capturing the structural
support member 168 between the shell and bladder does not require
bonding of the support member directly to the shell 132, yet
maintains the support in sufficiently close proximity to the shell
so as to provide fortification to the outer layer and covering.
[0089] FIG. 11 shows a detail of the arrangement of layers that
form the covering 110 shown in FIGS. 8-10A. As shown in FIG. 11,
the outer layer 122 may be considered as comprising all layers
arranged external to the liquid held in the bladder 126. The inner
layer 124 may be considered as comprising all layers positioned
internal of the liquid held in the bladder: between the user's limb
and the liquid. Thus, the outer layer 122, at its outermost
surface, comprises a shell 132 that is flexible and may serve as a
loop portion of a Velcro fastener. A suggested material for
achieving this purpose is an engageable knit loop fabric as
discussed above. On the inside surface 136 of the shell 132, a
polyurethane coating 134 is applied as a backing material. Next, a
structural support member 168, such as a polymer foam material may
be adhered or bonded directly to the inside surface 136 of the
shell 132, or may be captured against the shell 132 by a wall 138b
of the bladder. The bladder 126 is a self-contained unit comprising
two walls 138a and 138b with the interior of the bladder 126
defined therebetween. As a self-contained unit, the bladder walls
138a and 138b are bonded to each other around their peripheries 140
(not shown in FIG. 11). When incorporated into the covering, the
bladder is bonded to the inside surface 136 of the shell,
continuously along the outer peripheries 140 of the bladder walls
along seam 148. A suitable material for the double wall bladder is
a polyurethane film, on the order of approximately 0.008" in
thickness. A suitable film is available under the trade name
Duraflex under part no. PT9200US/Natural available from Deerfield
Urethane, Deerfield, Mass. The bladder may be joined to the shell
132 by any of the bonding techniques mentioned above in connection
with the first embodiment, such as RF welding, sonic welding,
adhesive or chemical bonding or stitching.
[0090] In comparison with the first embodiment, discussed in
connection with FIGS. 1-7, and in consideration of the premise that
layers on the patient side of the liquid comprise the inner layer,
the single inner wall 138a of the bladder may be considered to
represent the inner layer 124 in the covering embodiment 110. The
resulting combination of layers provides a substantially
non-distensible outer layer 122 and a distensible inner layer 124,
with a liquid tight bladder 126 therebetween. The covering
embodiment 110 may also be defined as comprising an inelastic shell
132 joined to an elastic double wall bladder with a structural
support member captured between the shell and bladder.
[0091] Optionally, a soft material 144 may be provided as a liner
over the inner layer 124 defined by bladder wall 138 to provide for
a more comfortable surface that will be in contact with the skin of
the user. A soft material 144 should cover the entire surface of
the inner layer 124 and may be joined to the covering by adhesive,
bonding, or stitching to the outer layer 122. Alternatively, the
cloth liner 144 may be implemented as a stocking that is. worn over
the limb separately, donned prior to placing on the covering 110.
The liner 144 should be of a material that does not interfere with
the distensibility of the inner layer 124 during use.
[0092] FIGS. 12-14 illustrate pattern shapes useful in forming the
therapeutic covering 110. FIG. 12 shows a pattern for both the
double wall bladder 126 and the shell 132. The shell 132 is
represented by the outer-dashed line and the double wall bladder is
represented by the inner-dashed line, both lines tracing a similar
pattern. The double wall bladder pattern, though following the same
shape as the shell pattern, is slightly smaller to provide a
bonding area at the outer periphery 140 of the bladder walls to
create a seam 148 that joins the bladder to the shell. As can be
seen in FIG. 12, the patterns are substantially the same through
the calf area 112 and foot portion 114, including defining the
shape of flaps 127, that are ultimately used to secure the covering
to a limb. One difference between the pattern shapes can be seen at
the bottom of foot portion 114 where only the bladder defines left
and right sole tabs 152 and 154. Identification of left and right
sides corresponds to the perspective of a user wearing the
covering. The sole tabs 152 and 154 comprise the same double wall
bladder 126 that extends through the covering. The sole tabs are
not covered by the shell material. In the final construction of the
covering, the sole tabs will be folded upward from their position
shown in FIG. 12 to reside horizontally on top of the sole portion
172 as is shown in FIG. 8 and as will be discussed further
below.
[0093] FIGS. 13 and 13A show patterns for both a structural support
member 168 and the sole insert 177, both of which may be formed
from closed-cell polymer foam material such as that discussed
above. The structural support 168 shown in FIG. 13 is cut to
substantially follow the pattern of the shell 132 shown in FIG. 12.
However, the structural support need not follow the shell pattern
in the more intricate areas of the flaps 127 because its primary
function is to provide column support to the calf portion of the
covering. The structural support is not needed in the flaps, which
wrap over the top of the foot. However, wing extensions 156 which
correspond with at least one series of flaps 127 of the outer wall
122 may be formed in the structural support 168 to help locate it
and prevent it from sliding in its sandwiched position between the
double wall bladder 126 and shell 132. As discussed previously, the
structural support may be provided with an arch 169 that rises over
the top of the heel to better accommodate this protruding portion
of the foot. With the arch 169, two extension tabs 158 are defined
on either side and serve to continue the structural support down to
the base of the calf portion of the covering. To improve
flexibility in the Achilles tendon area, several notches 159 may be
cut out from the support material above the arch.
[0094] FIG. 13A shows a sole insert 177 that will reside in the
sole portion 172 of the covering to provide a base that helps
maintain the form of the covering and also serves to cushion the
bottom of the users foot during ambulation. The sole insert 177 has
a more narrow width at the heel area 181, which gradually widens
along its length to a maximum width at the toe area 179 of the sole
insert. However, it is noted that in the configuration of an open
toe covering, as has been shown in the figures and descriptions,
the toe area 179 will actually correspond to the ball of the foot
of the user.
[0095] FIG. 14 shows the patterns discussed in connection with
FIGS. 12-13 overlying each other as they would appear in the
assembled covering. Additionally, the securement mechanism 130 is
also shown. As mentioned above, the securement mechanism 130 may
comprise Velcro hook portions 131 joined to flaps 127 that are
formed in the outer layer 122. The outer periphery of the bladder
140 is bonded to the shell 132 of the outer layer 122 to form a
seal 148 to secure the bladder to the covering. The structural
support 168 is captured between the double wall bladder 126 and
shell 132. Along the bottom of the covering, the sole tabs 152 and
154 extend from the bonded structure of the shell 132 and bladder
126. However, it is emphasized, that the sole tabs 152 and 154 are
a continuation of the double wall bladder 126 and are open to the
interior chamber of the bladder to be filled along with the
bladder. To permit the sole tabs 152 and 154 to remain open to the
remaining portion of the bladder 126, the seal 148 is discontinued
along the portion of the covering that corresponds with the tabs.
Additionally, the bladder may, but need not be, bonded to the shell
132 along the heel portion 183 of the covering, between the tabs
152 and 154. The sole 172 is formed as a separate component
comprising the sole insert 177, which is covered by a layer of
shell material 132 over its entire surface. The sole component 172
may then be bonded to the foot portion 114 of the covering along
its edges 185. Before the sole portion 172 is bonded to the
covering tabs 152, 154 are folded upward, so that after bonding,
they may lie flat on top of the sole portion, overlapping each
other, as is shown in FIGS. 8 and 15A and 15B.
[0096] FIGS. 15A and 15B represent an overhead view of the sole
portion 172 with the opening 128 of the covering 110 opened to
permit viewing of the configuration of the sole area. As shown in
FIG. 15A after the sole portion 172 has been bonded along its edges
185 to the foot portion 114 of the covering, the tabs 152 and 154
may be folded down to lie on top of the sole 172. FIG. 15A shows
the right sole tab 154 being folded down onto the sole portion 172,
first, prior to folding of the left sole tab 152. FIG. 15B shows
the left sole tab 152 then being folded down on top of the right
sole tab 154, both tabs thus lying horizontally on top of the sole
172. The tabs may be left free to fold up and down away from the
sole, or may be secured to the sole by bonding. If secured, the
sole tabs should be secured only at front and back edges. 182 and
184. The sides of the sole tabs 186 and 188 should be left unbonded
to permit communication between the tabs and the remainder of the
bladder 126.
[0097] FIG. 16 is a sectional view of the foot portion 114 taken
along the line 16-16 of FIG. 9, but with the additional element of
a user's foot 21 shown inside. The view shows that left and right
sole tabs overlie each other and reside between the user's foot 19
and the sole portion 172. The bladder 126 surrounds the user's foot
by its extension through left and right sole tabs 152 and 154 and
by the overlapping securement achieved on top of the foot by flaps
127 being secured by hook portion 131 to shell 132 of the
covering.
[0098] The arrangement of sole tabs 152 and 154 beneath the foot
creates movement of the liquid contained in the bladder 126 during
ambulation that is believed to improve the therapeutic benefit of
the covering. As shown in FIGS. 17 and 18, a user wearing the
covering 110 will compress and release the sole tabs 152 and 154
during ambulation that serves to compress and release this portion
of the bladder 126 to cause movement of the liquid therein. In FIG.
17, the user is stepping down onto the sole 172 of the covering
serving to compress the left and right sole tabs, reducing their
volume and squeezing out liquid contained therein. Because the sole
tabs define a continuation of the bladder 126 that extends around
the side of the foot and beneath the sole of the foot, the liquid
squeezed out of the tabs tends to be forced upward into the upper
regions of the bladder 126 as indicated by flow arrows 190. The
upward flow of the liquid is believed to help promote upward venous
flow in the limb. FIG. 18 illustrates the flow of liquid when the
user lifts the limb 19, as during ambulation, which serves to
remove pressure from the left and right sole tabs 152 and 154.
Without weight to bear on the sole tabs, the force of gravity on
the liquid contained in the bladder 126 causes the tabs to quickly
fill with liquid again. The filled left and right sole tabs are
thus quickly made ready for the next step of the user so that
another upward moving pressure wave can be created throughout the
bladder 126 to promote the venous flow in the limb. It is noted
that a sole portion configured as a single integrated piece as
shown in FIGS. 1-7 defined by trunk portion 52, will also provide
pumping action of the bladder liquid during ambulation. As shown in
FIG. 4, when the user places weight on their foot 21, the bladder
26 will be compressed to cause a upward pressure wave through the
liquid to stimulate the lower leg.
[0099] Another embodiment of the limb covering configured to be
worn about the foot is shown in FIG. 19. This boot-type embodiment
is similar in construction and configuration to the previous
embodiment described in connection with FIGS. 8-18 but additionally
includes a tongue portion 204 that is movable relative to the main
body portion of the boot covering and configured similar to a
tongue found on a conventional shoe or boot. The tongue 204 is
configured to lie along the instep portion of a user's foot and
extends up along the shin of the lower leg. In FIG. 19, the
tongue-type limb covering 200 is shown on a patient's leg 19 and
foot 21 but opened to show the tongue portion 204. It is noted that
components of the tongue type limb covering embodiment that are
unchanged from previous boot embodiments are numbered with similar
reference numerals in the 200 series in FIGS. 19 through 26.
Identical features of both embodiments include inner layer 224,
outer layer 222, structural support 268 and fill port 264, which
are not discussed in detail again here.
[0100] In use the tongue is in position so that it inner surface is
in contact with the shin portion of the limb 19 and instep portion
of the foot 21 of the user. The outer surface of the tongue is in
contact with the inner layer 224 of the covering 200. The tongue
204 should be compliant to form easily around the patient's limb
and to take advantage of the form fitting nature of the liquid
bladder 226 that surrounds it from the outside once it is secured
in position. The tongue itself may be formed to have a liquid
filled bladder 211 to help make it compliant. The liquid filled
bladder tongue may be formed from a construction similar to that of
the bladder of the main limb covering: a double layer of urethane
sealed together at their peripheries to define a bladder between
the layers. The tongue may or may not additionally have the second
outer layer of non-distensible material used in the main covering.
It is acceptable that the tongue be distensible in both its inner
and outer layers because it will ultimately be surrounded by the
main limb covering having the outer non-distensible layer. The
urethane inner wall of the tongue bladder may be on the order of
0.006 inch in thickness and is compliant to form to the shape of
the user's limb. The outer wall of the tongue bladder may be formed
from urethane on the order of 0.010 inch in thickness. A compliant
tongue outer layer is useful to absorb any gaps that may occur at
the opening 228 of the covering where the edges 229 must overlap
interrupting the surface of the bladder 226. However, because the
outer wall is not in contact with the limb, some additional
thickness of provides additional strength to help hold the shape of
the tongue under the weight of liquid.
[0101] The tongue 204 may be permanently or removably attached to
the boot limb covering. If permanently attached to the limb
covering, it is expected that the tongue would be stitched or
otherwise fastened to the end of the instep or foot portion 214, at
or near the toe opening 216 of the device. The tongue should be
free to pivot upward and outwardly when the covering is opened so
that the limb can easily enter or withdraw from the covering. In
the embodiment shown in FIG. 19, the tongue 204 is made to be
completely removable from the covering and is made releasably
attachable to the covering at one or more anchor points such as top
anchor 261 and bottom anchor 259, shown in FIGS. 19-21. The anchor
points may be configured as flaps having releasable attachment
means engageable with the main body of the covering 200. Buckles,
snaps or hook and loop fastener pieces 231 may be used to
releasably secure the tongue to the covering.
[0102] The tongue is placed in position over the instep and shin
before securing the boot to the leg. As shown in FIG. 19, after the
covering 200 has been positioned around the limb, but while still
open, the tongue is laid over the instep of the foot 21 and on the
shin area of the leg 19. The boot is closed around the tongue such
that opposing edges 229 of the opening 228 overlap and cover it.
Flaps 227 on the calf portion 212 and foot portion 214 are
overlapped to latch onto the opposing edge 229 of the opening by
means such as hook and loop fasteners 231. Bottom and top anchors
259 and 261 are left uncovered by the closed boot and project from
the toe opening 216 and calf opening 218, respectively. After
closing the boot over the tongue and securing flaps 227 to the
opposing edge of the covering, anchors 259 and 261 may be secured
to hold the tongue in place on the boot. As shown in FIG. 20, the
anchors 259 and 261, while previously protruding from the closed
boot, are folded over and secured to the outer surface 222 of the
boot by releasable means such as hook and loop fastener material
231 that is secured to the flaps.
[0103] An example of a tongue component 204 configured to be
releasable is shown in detail in FIG. 21. The tongue may be
configured to be tapered along its length. A body portion 205 of
the tongue may be made narrow at the top 206 gradually widening
near the bottom of the body portion 207. The body should be
compliant to conform to the limb and to absorb discontinuities on
the inside of the boot covering that may be present at the opening
228. As mentioned above, a liquid-tight bladder 211 may be formed
along the body 205 to hold a convenient liquid such as water. The
bladder 211 is formed between two layers of flexible liquid tight
material, such as urethane resulting in a fully compliant structure
to engage the limb. Alternatively, the body 205 of the tongue may
be formed without a liquid tight bladder, but may comprise only a
compliant material such as foam capable of easily absorbing the
varied contours of the limb.
[0104] A tapered shape is not critical to the function of the
tongue but is believed to coincide with possible gaps and less
securely fitted areas of the boot when it is donned on a foot. The
wider section at the bottom of the tongue coincides with the more
flexible region of the ankle that tends to be more difficult to
surround tightly by a single covering. Extending from the top 206
of the tongue is the top anchor 261, which may be more narrow width
than the tongue body portion. Also, adjacent the top 206 of the
tongue is placed a liquid transfer valve 253 in communication with
the bladder 211 of the tongue to permit liquid to be added then the
bladder sealed. The bottom anchor 259 extends from the bottom 207
of the tongue body 205. A tapered transition region 208 extends
between the bottom of the tongue 207 and the bottom anchor 259 to
provide a gradual transition from wide to narrow between the
components. The tapered portion may comprise a stepped
configuration having an initial taper 209 leading to a more gradual
tapered section 208 that is flexibly joined to the bottom anchor
259.
[0105] As best seen in the side view of FIG. 21B, the tongue
optionally may be formed to have a pre-set curvature that follows
the contour of instep of the foot as it transitions to the shin
portion of the leg. A corresponding instep portion 217 and shin
portion 223 of the tongue 204 are identified in FIG. 21B. With the
desired amount of curvature, the instep portion 217 is maintained
in a substantially horizontal orientation, substantially
perpendicular to the shin portion 223, which is maintained in
substantially vertical orientation. Additionally, an inside surface
225 of the tongue, along the instep and shin portions 217 and 223,
may be configured to be concave (convex appearance on the outer
surface). The convex shape and curve angle between the instep and
shin portions help to more comfortably receive the user's limb,
which has a rounded cross-sectional shape and which bends at the
ankle from the vertical orientation of the leg to the horizontal
orientation of the foot.
[0106] The flexible tongue may be configured to hold a curve
between the instep and shin portions 217 and 223 and hold a concave
inside surface shape by the adding additional material along edges
237 of the tongue, in both urethane layers, through an instep/shin
transition region 235. The extra material on the edges maybe
planned in the pattern from which the tongue inner and outer layers
are cut so that extra material is provided in the sheets of
material that will ultimately be joined to form the tongue.
Alternatively, extra material can be added to the tongue layers
during manufacture, such as wedge inserts 213 inserted into notches
215 cut in the edges 237 of the tongue along the transition region
235.
[0107] The wedge inserts 213 are pieces of flexible bladder
material, preferably the same material that is used for the tongue
layers: urethane. The wedges of extra material are triangular in
shape to fit into a notch 215 that has been spread apart to define
a triangular opening (shown in phantom at 215 in FIG. 21B). Because
both the inner and outer layers have the notches 215 cut through
them, two wedges 213 are needed at each notch location. A wedge is
joined into each notch (one in the inner and one in the outer
layer) at each location, before the two layers are bonded together
along their peripheries to form the bladder 211. The wedges may be
bonded into the spread notches by means such as RF welding. The
excess material created by the wedges 213, when inserted along the
edges 237 of each tongue layer (inner & outer) causes the
otherwise flat piece of material to distort, forming a curved
surface. The curved surface makes the tongue concave as viewed from
its inner surface and makes the shin portion 223 orient
substantially perpendicular to the instep portion 217 when the
wedges are placed through the transition region 235. The number and
size of the notches and wedges of material inserted through the
transition region 235 can be modified to change the amount of
curvature. It has been found that two sets of notches and wedges
per side through the transition region, of a relative size and
orientation shown in FIG. 21A are suitable to form a comfortable
shape to the tongue for most users.
[0108] Securement of the tongue type covering 200, as well as the
previously described leg coverings 10 and 110, may be augmented
with one or more removable straps 251 as shown in FIGS. 19A, 19B
and 20. The removable straps 251 are configured to be attachable to
the outside surface 222 of the boot to help tighten its fit about
the limb and preferably may be applied at any desired location to
provide a fully adjustable securement mechanism. It is expected
that the removable strap 251 may be most useful applied across the
ankle section of the boot between the instep and shin as shown in
FIG. 20. The ankle area of the boot may be considered more
difficult to cover securely with a single covering because its
active flexure creates loosening and gaps in the surfaces of the
covering that contact the limb. At the bending area of the ankle
bunching of the covering can occur that may loosen the fit of the
covering. An additional strap of smaller cross-section such as
strap 251 provides a more focused area of tightening through the
high flexure and bending area serving to take up slack and keeping
the area of the covering secure against the limb.
[0109] As shown in FIG. 19B, the underside of the removable strap
251 that contacts the surface of the covering may be provided with
a releasable securement mechanisms at its ends such as hook and
loop fastener patches 231 for attachment to the material of the
outer layer 222 at any preferred location. Alternatively, snaps or
buckles could be used but would require receiving receptacles at
permanently fixed locations on the exterior of the covering. Hook
and loop fasteners are advantageous because they can be secured
anywhere on a soft cotton surface of the outer layer 222 of the
covering.
[0110] Through the center area of the removable strap is a
resilient pad 255 to provide support and cushion to the underlying
area of the covering. A pliable material for pad 255 may be any
pliable cushion material such as foam or it may be a bladder filled
with liquid. FIG. 19A shows the front side of the removable strap
251 with releasable securement mechanisms of hook and loop
fasteners 231 and the central pliable pad 255 shown in phantom.
FIG. 20 shows a removable strap 251 partially attached, at one
side, to the ankle area of a tongue type leg covering 200. To
complete securement, the free side of the strap is brought over the
instep area of the foot and the remaining hook and loop fastener
section 231 is joined to the opposite side of the boot near the
ankle. In the secured configuration, the removable strap will cover
a cutout 203, which exposes a portion of the tongue 204. The
pliable section 255 of the removable strap 251 will cover the
opening 203 and provide support to the tongue while permitting
flexibility through the ankle area of the boot that will minimize
bunching of the covering.
[0111] FIG. 22 shows a diagrammatic representation of a suitable
pattern for the tongue boot-type covering 200 including an
indication of a possible placement of the removable strap 251.
Removable strap 251 with center pad 255 and hook and loop fasteners
231 is shown detached to the right of the pattern 200 and is shown
again in phantom in a possible mounting location with one end
attached to the outer layer 222 of the covering. In the pattern
drawing of FIG. 23 it can be seen that with the detachable strap
251 fewer individual securement flaps 227 need to be formed in the
pattern in the instep area as compared to the flaps 127 shown on
the pattern of the previous embodiment in FIG. 14. Cutout 203
formed in the pattern to reduce bunching of material at the bending
area of the ankle can be more aggressive because the large
detachable strap 251 can be applied over it on the ankle/instep
area to keep the covering tight against the tongue 204.
[0112] In other respects, the tongue type pattern 200 may be formed
similarly to that of the previous embodiment. Inner layer 224 is
bonded to outer layer 222 along seam 240 capturing structural
support member therebetween. Also defined between the inner and
outer layers 224 and 222 is the bladder 226. The bladder is filled
through a liquid transfer valve 262. The sole 272 is formed from a
sole insert 277 that is formed to the outer layer 222 in the
completed covering. Left sole tab 252 and right sole tab 254,
extensions of the bladder 226, overlay the sole inset 277 in
use.
[0113] FIG. 23 is a cross-sectional view of the tongue-type
embodiment 200 taken along the line 23-23 shown in FIG. 20. A
liquid filled bladder 211 of the tongue 204 can be seen filling the
space adjacent to the opening 228 where the edges 229 of the
opening meet and overlap to permit the securement mechanism 230 of
flaps 227 to be secured. Where the ends of the boot covering
bladder 226 meet at the opening, the tongue 204 smooths the
transition and gap that would ordinarily be present at this
juncture. The liquid filled bladder 211 is maintained against the
limb 19. In the secured position, the tongue 204 is supported and
retained by the covering secured around it, namely by the inner
layer 224, filled bladder 226 and structural support 268 along with
outer shell 222.
[0114] FIG. 24 is a cross-sectional drawing taken along the line
24-24 of FIG. 20. The tongue 204 is positioned to take up the space
left at the opening 228 of the covering 200 that occurs between the
edges 229 so that limb 19 is secured. Removable strap 251 provides
support to the tongue over the cut out opening 203 by corresponding
placement of the resilient material 255 over the opening so that it
contacts the surface of the tongue bladder 211. The releasable
fastener material 231 of the strap 251 engages the edges of the
outer layer 222 of the covering 200 to secure the strap in
place.
[0115] FIG. 25 shows a cross-sectional view of the foot portion 214
of the tongue type limb covering taken along the line 25-25 in FIG.
20. Foot 21 is surrounded by bladder 226 of the foot portion 214 of
the covering as with the previous embodiment. The bottom of the
foot is supported by left and right flaps 252 and 254 overlying
each other and overlying foam support 272. However, the top of the
foot 21 is surrounded not only by the bladder 226 overlying and
straps 227 but also the bladder 211 of tongue 204 is present to
help fill in any gaps that occur at the transition between the
edges 229 at the opening 228 of the covering 200.
[0116] FIG. 26A shows the magnitude of the hydrodynamic forces on
the foot at the cross-sectional location indicated at line 25-25 in
FIG. 20. Arrows 257 represent hydrodynamic forces applied to the
foot and exterior layer 222 by the liquid contained in bladder 226
and in the bladder of tongue 204. The length of the arrows
represents the comparative magnitude of the force at a given
location height due to hydrostatic pressure. FIG. 26B is a
graphical representation of the magnitude of forces increasing as
height of the water column above the given location increases.
Consequently, the hydrostatic pressure applied to the limb
increases at lower regions where the water column above a given
location is higher.
[0117] FIG. 27 shows an embodiment of the limb covering configured
to be worn about an arm. The arm covering 86 comprises a tubular
sleeve of a length sufficient to cover the extent of the arm. The
covering may be secured to the arm at the top by shoulder strap 88
having its ends joined to opposing sides of shoulder opening 90 of
the covering. The strap extends around the patient's back (shown in
phantom), loops around the neck 92 and opposite shoulder and
extends back across the patient's chest 94 to the shoulder opening
90. To facilitate donning, a releasable buckle 100 may be provided
on the strap to permit is detachment from the covering. Also the
strap may be provided with a length adjustment to accommodate a
variety of patient sizes. The arm covering is restrained from
sliding up the arm by its gradual tapered shape as it drawn upward
against the gradually increasing diameter of the arm. Additionally
or alternatively the arm covering may be restrained at the hand
opening 102 by a thumb loop 104 that comprises a tapered strap of
covering material extending across the hand opening 102 and
configured to fit between the thumb 108 and forefinger 109a of a
patient's hand. The arm covering is otherwise configured in the
same manner as the boot embodiment described above. The arm
covering has a distensible inner layer and a non-distensible outer
layer with a liquid tight bladder defined therebetween. A sealable
port 106 in communication with the bladder is provided at the top
of the arm covering. Materials and methods of fabricating are also
the same as those used for the boot limb covering.
[0118] To create alternating upward movement of the liquid through
the arm covering for added therapeutic as described above in
connection with the boot embodiments, a manual compression bulb
area 103 may be integrated in the arm covering as shown in FIG.
27A. The manual compression area 103 (shown in phantom in FIG. 27)
should lay comfortably in the palm 107 of the hand for compression
by the user's fingers 109 and palm 107. The bulb should be in
communication with the bladder of the device so that compression
and expansion of the bulb volume results in pressure changes in the
bladder that serve to urge liquid, to or away from the bulb.
Preferably, the manual compression bulb area comprises an extension
of the covering and its bladder to the palm area 107 of the hand,
without additional specialized components. By compression and
release of the bulb, the desired liquid movement can be achieved,
as is demonstrated in FIG. 27A showing the flow 190 of liquid
moving toward the user's palm upon release and expansion of the
bulb area 103. Liquid flows downward to the palm under the force of
gravity to fill the bladder area defined by the bulb 103. The
filled bulb area is then ready for the next compression by the
user's hand to drive the flow 190 of liquid up the arm.
[0119] In use, the patient places the limb covering around the limb
19 prior to filling it with liquid. In the case of a boot limb
covering releasable securement mechanism 30 is released to open the
limb covering to permit donning over a bare foot or stocking and
foot. It is noted that the following description of use refers to
the boot 10 for simplicity, but that it should be understood that
the boot embodiment 110 is used in the same manner. After the
covering is slipped on so that the foot portion 14 covers the foot
of the user, the securement mechanism 30 may be secured to tighten
the calf portion 12 about the calf of the user. If provided, size
adjusters 31 or Velcro fasteners may be tightened to customize the
fit of the covering. A loose fitting shoe may then be slipped over
the foot portion 14 of the covering. Liquid may then be added to
the bladder 26 of the covering 10 through valve 62.
[0120] As shown in FIG. 28, liquid is added through valve 62 to the
boot 10 that has been placed on the limb 19. A liquid supply line
72 may be joined to the valve 62 by a lure type fitting or a quick
connect type connection as discussed above. The liquid supply line
72 is in communication with a liquid reservoir 74 filled with any
convenient liquid such as water 78. Liquid may be transferred from
the reservoir 74 through the supply line 72 by pressure developed
from a pump or a syringe 76. To facilitate use of the syringe, a
three-way stopcock 80 may be used to join the syringe to the supply
line 72. When the stopcock is closed to the boot but open to the
syringe 76 and reservoir 74, a vacuum may be drawn by the syringe
to fill it with liquid. Next, the stopcock is opened to the boot
and syringe and closed to the reservoir so that the syringe may be
pressurized to move the collected liquid into the boot. Liquid can
be transferred to the boot until it appears full to the user or
until a prescribed volume or pressure has been reached as measured
using the syringe.
[0121] Alternatively, as shown in FIG. 29, liquid may be
transferred from the reservoir 74 through supply line 72 to the
boot 10 via the force of gravity. In this situation, the liquid
reservoir, perhaps comprising a sealable bag, is elevated above the
boot 10 to permit liquid to flow freely into the boot under the
force of gravity. By this method, a pressure that has been
clinically prescribed by a physician can be transferred by
elevating the reservoir 74 to a measured height 79, known to
correspond with a known pressure of liquid that will be dispensed
from the reservoir to fill in the limb covering to a desired column
height to deliver the needed pressure. Because the pressure applied
to the limb by the present invention can be determined easily by
measurement of the pressure of liquid that is transferred into the
bladder, treatments can be prescribed more accurately by a
physician and more accurately followed by the patient. In contrast,
it is difficult to determine what pressure will be achieved with
prior art wrapping materials because there effectiveness in
applying pressure is highly dependent on the technique used by the
one applying them.
[0122] An advantage of the hydrostatic pressure exerted by the limb
covering is the linear increase in pressure that is applied at
lower portions of the liquid column maintained in the covering.
This characteristic of hydrostatic pressure is illustrated
diagrammatically in FIG. 30 in which the boot 10 is shown with
arrows 82 shown as graphical representations of the hydrostatic
pressure forces exerted by the liquid column. The length of each
arrow 82 relates directly to the magnitude of pressure force
applied by the hydrostatic pressure of liquid contained in the limb
covering at that point. Due to gravity, hydrostatic pressure forces
increase linearly from the top of the covering to the bottom as is
shown graphically by pressure profile line 83. However, pressure
forces do not increase or decrease along a common horizontal plane,
such as shown along foot portion 14.
[0123] It should also be recognized that the magnitude of force
applied at a given point against the limb is not dependent on the
volume of liquid maintained along the same horizontal plane
extending from that point, but rather, hydrostatic force is solely
dependent on and proportional to the height of the liquid column
above it. The limb covering takes advantage of this effect by
maintaining a thin liquid column around the limb and maintaining
the height of the liquid column by its inelastic outer layer.
Restraining the horizontal extent of the liquid in the bladder
minimizes weight and to help maintain patient mobility without
reducing the hydrostatic pressure applied to the limb.
[0124] Though the magnitude of force provided by hydrostatic
pressure at any point along the limb is dependent on the height of
the liquid column above that point, the total amount of force
applied against the limb at any point can be increased by the
amount of pre-charge pressure captured in the bladder during
filling. The pre-charge pressure is created by over-filling the
bladder with a volume of liquid that increases the pressure of the
liquid above the pressure that is be created by hydrostatic effects
alone. After the bladder is pressurized to have a pre-charge
pressure during filling, sealing the port while maintaining the
pressure in the liquid transfer line and bladder ensures that the
pre-charge pressure will be maintained in the bladder.
[0125] In the situation discussed above in connection with FIG. 30,
a volume of liquid is contained in the bladder sufficient only to
provide force by hydrostatic pressure. The force applied at the top
87 of the covering is zero because the liquid column height does
not extend beyond that point. FIG. 30A demonstrates the effect of
adding to the bladder a volume of liquid sufficient to create a
pressure pre-charge. The bladder containing the extra amount of
liquid added to create the added pre-charged pressure may be
considered to be "over-filled" in the sense that additional liquid
has been added beyond what is required to fill the bladder to
capacity with out creating extra pressure. As shown by pre-charge
pressure profile line 85 in FIG. 30A, the pre-charge pressure
supplements the hydrostatic pressure to increase the total
magnitude of force applied to the limb at any given point. Thus the
total pressure applied to the limb by the filled covering at any
given point may be expressed as:
Total Pressure=Hydrostatic Pressure+Pre-charge Pressure
[0126] Compared to the scenario shown in FIG. 30 the pressure at
the top of the covering 87 of the pre-charged covering in FIG. 30A
is not zero, but is equal to amount of pre-charge pressure that has
been created. The amount of hydrostatic pressure at top 87 of the
pre-charged covering is still zero, but because the total pressure
at any point is the sum of pre-charge pressure plus hydrostatic
pressure, the total pressure at the top 87 is equal to the
pre-charge pressure. The pre-charge pressure value is constant
throughout the bladder. The hydrostatic pressure at all other
points in the covering of FIG. 30A having a pre-charge is increased
by the constant amount of the pre-charge pressure. In FIG. 30A, the
amount of pre-charge pressure is equal to the .DELTA.P shown
between the pressure profile 83 of hydrostatic pressure alone and
the pressure profile 85 created in a covering that has been
pre-charged with additional pressure.
[0127] It may be desirable to increase the pressure applied to the
limb by adding a pre-charge pressure for certain treatments
prescribed by a physician. If the bladder is filled with a syringe
as described above, the pre-charge may be created by continuing to
displace liquid volume with the syringe until the desired
pre-charge pressure is achieved as measured at the at the top of
the boot or at the syringe when it is maintained at the same height
as the liquid transfer valve at the top of the boot. When filling
the bladder to have a pre-charge pressure it should be understood
that the pressure being measured at the port on the top of the
covering does not include the hydrostatic pressure component that
will exist at lower points in the bladder. If the bladder is filled
by gravity feed as discussed in connection with FIG. 29, the liquid
reservoir 74 may be elevated to a greater height to increase the
magnitude of pressure experienced at the port 62 of the covering. A
prescribed height 79 can be calculated with consideration of an
appropriate pre-charge value. Alternatively, a pre-charge pressure
can effectively be created after filling of the bladder by using
adjusting straps 31 to tighten the covering about the limb and
reduce the volume of the bladder.
[0128] FIG. 31 shows another diagrammatic illustration of
hydrostatic forces as they exist in a boot limb covering, without a
pre-charge pressure, oriented horizontally. The illustration mimics
the circumstance when a patient may be lying in bed and the calf is
oriented horizontally while the foot is arranged vertically. As
with the previous diagram, it can be seen that forces applied to
the limb do not change with position along the horizontal axis.
Rather, the point forces increase linearly as point height
decreases. Much of the limb that experienced high pressures in the
vertical position shown in FIG. 30 now experience reduced pressure
because the height of the liquid column maintained above those limb
areas has been reduced. By this characteristic of hydrostatic
pressure the present limb covering becomes a suitable therapy
device for patients suffering from poor arterial perfusion. Those
patients can treat chronic swelling with the therapeutic limb
covering by maintaining their limb in a vertical orientation for a
period of time, then alternately reorient their limb to a
horizontal orientation to temporarily reduce pressure to the limb
and allow blood to flow into the limb area. Because the device need
not be removed or emptied to reduce pressure, alternatingly
treating a limb with pressure then relieving the pressure becomes a
practical treatment scheme for one with both chronic swelling and
arterial perfusion problems.
[0129] Additionally, in the horizontal position, the hydrostatic
pressure applied by the limb covering to the bottom of the calf 84
is beneficial to support the limb on a patient-supporting surface
to avoid the incidence of pressure ulcers that may develop in a
bedridden patient. It is noted that the hydrostatic forces and
pressure profile line experienced in an arm covering with the arm
positioned vertically and horizontally would be similar to those
shown for the boot embodiment in FIGS. 30-30A.
[0130] FIG. 32 is a graphical representation of the linear increase
in hydrostatic pressure as plotted in the skin contact pressure per
water column height maintained in the limb covering.
[0131] It should be understood, however, that the foregoing
description of the invention is intended merely to be illustrative
thereof and that other modifications, embodiments and equivalents
may be apparent to those skilled in the art without departing from
its spirit. Having thus described the invention what we desire to
claim and secure by letters patent is:
* * * * *