U.S. patent application number 13/934773 was filed with the patent office on 2013-11-07 for wound packing material for use with suction.
The applicant listed for this patent is Boehringer Laboratories, Inc.. Invention is credited to Carol Boehringer (Legal Rep. of John R. Boehringer), John Karpowicz, Amitabha Mitra, Christopher L. Radl.
Application Number | 20130296815 13/934773 |
Document ID | / |
Family ID | 34987320 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130296815 |
Kind Code |
A1 |
Boehringer (Legal Rep. of John R.
Boehringer); Carol ; et al. |
November 7, 2013 |
WOUND PACKING MATERIAL FOR USE WITH SUCTION
Abstract
A wound packing for use with suction is provided. The wound
packing comprises a plurality of nonabsorbent synthetic polymeric
fibers coupled together to form a nonabsorbent material suitable
for placement in the wound of a mammal. A method for treating the
wound in a mammal using the disclosed wound packing is also
provided.
Inventors: |
Boehringer (Legal Rep. of John R.
Boehringer); Carol; (Wynnewood, PA) ; Karpowicz;
John; (Chester Springs, PA) ; Mitra; Amitabha;
(Voorhees, NJ) ; Radl; Christopher L.; (Malvern,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boehringer Laboratories, Inc. |
Phoenixville |
PA |
US |
|
|
Family ID: |
34987320 |
Appl. No.: |
13/934773 |
Filed: |
July 3, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12824650 |
Jun 28, 2010 |
8500704 |
|
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13934773 |
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10981119 |
Nov 4, 2004 |
7754937 |
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12824650 |
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60554158 |
Mar 18, 2004 |
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Current U.S.
Class: |
604/319 |
Current CPC
Class: |
A61M 1/0088 20130101;
A61F 13/00068 20130101; A61F 13/36 20130101 |
Class at
Publication: |
604/319 |
International
Class: |
A61F 13/00 20060101
A61F013/00 |
Claims
1-76. (canceled)
77. A wound packing for use with suction comprising: a plurality of
nonabsorbent synthetic polymeric monofilaments randomly coupled
together to form a nonabsorbent material having a loft and suitable
for placement within a wound of a mammal.
78. A wound packing for use with suction comprising: a plurality of
nonabsorbent synthetic polymeric fibers randomly coupled together
to form a nonabsorbent material having a loft, suitable for
placement within a wound of a mammal, and having a first
compressive response along a first axis, and a second compressive
response along a second axis.
79. A wound packing for use with suction comprising: a plurality of
nonabsorbent polymeric fibers randomly coupled together in a
non-woven manner to form a substantially contiguous nonabsorbent
sheet of material such that the volume of aqueous liquid that can
be absorbed by the structure is no more than about one third of the
uncompressed volume of the packing.
80. The wound packing of claim 79 wherein the sheet of material
further comprises at least one planar surface and a piled structure
rising from the surface.
70. The wound packing of claim 67, wherein said synthetic polymeric
fibers are comprised of a polyamide.
71. The wound packing of claim 70 wherein said polyamide is
nylon.
72. The wound packing of claim 67 wherein said synthetic polymeric
fibers are comprised of polyester.
73. The wound packing of claim 43 wherein said fibers are coupled
together by a heat sealing means.
74. The wound packing of claim 43 wherein said fibers are coupled
together by an adhesive.
75. The wound packing of claim 74 wherein said adhesive comprises
silicone.
76. The wound packing of claim 43 wherein said fibers are coupled
together by one of spunbonding or meltblowing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This continuation application claims the benefit under 35
U.S.C. .sctn.120 of application Ser. No. 10/981,119 filed on Nov.
4, 2004 which in turn claims the benefit under 35 U.S.C.
.sctn.119(e) of provisional U.S. Patent Application No. 60/554,158
filed on Mar. 18, 2004 and all of whose disclosures are
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention relates to a device and method for treating
wounds. More specifically, the present invention relates to a
therapeutic wound packing material for use with suction and a
method of treatment employing the same.
BACKGROUND OF THE INVENTION
[0003] Large open chronic wounds typically secrete exudates during
the healing process. It is generally desirable to remove these
wound exudates from the wound vicinity to minimize bacterial growth
which can cause infection and delay healing. Excessive exposure to
wound exudates can result in maceration of the skin surrounding the
wound. Wound exudates are known to contain tissue degrading enzymes
that can impede wound healing. It is generally known to cope with
exudates of large open chronic wounds by packing them with an
absorbent packing such as gauze. Gauze packing fills dead space in
the wound and absorbs exudates released by the tissue over time.
Disadvantageously, the absorbent gauze must be replaced
periodically as it absorbs a larger volume of exudates and becomes
saturated.
[0004] Alternatively, removal of wound exudates can be accomplished
with suction. The wound is sealed generally by the application of a
cover and suction is applied to the wound to draw out exudates.
Often the suction is applied continuously for days or weeks. When
suction is used it can be beneficial to also use wound packing. The
wound packing provides passages from the areas where it contacts
the wound to communicate the exudates from the wound surface
towards the source of suction. When wound packing is used in
conjunction with suction it is generally found that wounds heal
more quickly and wound packing may be replaced less frequently
because exudates are continuously removed.
[0005] When absorbent wound packings such as gauze are used with
suction their highly absorbent characteristics are not required.
Cotton gauze typically absorbs from ten to twenty five times its
weight in aqueous liquid. This absorbent quality can be detrimental
because absorbent packings tend to retain volumes of exudates
within the wound cavity and adjacent the wound surface supporting
bacterial growth and enzymatic breakdown of tissue.
[0006] When suction has been applied to the wound, it is generally
desirable to permit the wound to contract. Wound contraction is a
normal part of wound healing, therefore using a packing that
encourages contraction, as opposed to inhibiting it, is desirable.
When a noncompressible wound packing, such as gauze, is used in
conjunction with suction, the wound contraction may be impeded by
the wound packing.
[0007] An alternative to gauze as a wound packing is foam. Foams
have the disadvantage that they are not readily modified by many
traditional methods, such as heat stamping, to produce a surface
texture after they are formed. Foam formation methods do not
readily lend themselves to the construction of composites. This
limits the extent to which multiple materials can be integrated
into the foam structure during the manufacturing process. Foam
materials are isotropic in that they exhibit uniform properties
such as absorbency, pore size etc. in all directions. When used
with suction foams, have the disadvantage that pieces can easily be
separated from the whole, when removed from the wound. This is
caused by new tissue growing into the foam structure. This can be
problematic because often it may not be possible to see the pieces
of foam that remain in the wound.
[0008] Hence, known wound packing materials have a number of
disadvantages and as such there is a need for a superior wound
packing.
SUMMARY OF THE INVENTION
[0009] To overcome the deficiencies of conventional wound treatment
techniques and devices, the present invention is a wound packing
material, a method for making the wound packing material, and a
method of treating a wound employing the wound packing
material.
[0010] According to an exemplary embodiment of the present
invention, a wound packing for stimulating the healing of a wound
in a mammal is provided. The exemplary wound packing comprises a
plurality of polymeric nonabsorbent fibers coupled together to form
a nonabsorbent material suitable for placement within a wound of a
mammal.
[0011] A further embodiment of the present invention is an
anisotropic packing. Another embodiment of the wound packing has
loft.
[0012] Yet a further embodiment of the wound packing is batting. An
additional embodiment of the wound packing is resilient.
[0013] An alternative embodiment of the wound packing includes a
wound healing substance incorporated into the component fibers
and/or coated onto the component fibers.
[0014] According to a yet further embodiment of the present
invention, a wound packing for stimulating the healing of a wound
is provided comprising a plurality of polymeric nonabsorbent fibers
randomly coupled together to form a sheet of nonabsorbent material
suitable for placement within a wound of a mammal.
[0015] Further aspects of the sheet embodiment of the present
invention are provided that comprise a corrugated three-dimensional
structure and methods of manufacturing the same.
[0016] According to another aspect of the present invention, a
method is provided for treating a wound of a mammal comprising the
steps of placing a fibrous nonabsorbent wound packing material in
contact with at least one surface of a wound and applying suction
to the wound and wound packing material.
[0017] These and other aspects will become apparent from the
following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention is best understood from the following detailed
description when read in connection with the accompanying drawing.
It is emphasized that, according to common practice, the various
features of the drawing are not to scale. On the contrary, the
dimensions of the various features are arbitrarily expanded or
reduced for clarity. Included in the drawing are the following
figures:
[0019] FIG. 1 is an illustration of an exemplary embodiment of a
wound packing material of the present invention;
[0020] FIG. 2 is a perspective view of an exemplary wound packing
sheet of the present invention;
[0021] FIG. 3A is a cross sectional view of a deep tissue
wound;
[0022] FIG. 3B is a cross sectional view of the deep tissue wound
of FIG. 3A illustrated in combination with an exemplary embodiment
of the present invention;
[0023] FIG. 4 is a perspective view of an exemplary corrugated unit
of the present wound packing invention;
[0024] FIG. 5A is a perspective view of an exemplary pleated wound
packing sheet of the present invention;
[0025] FIG. 5B is a perspective view of an exemplary contoured
wound packing sheet of the present invention;
[0026] FIG. 5C is a perspective view of an exemplary embossed wound
packing sheet of the present invention;
[0027] FIG. 5D is a perspective view of an exemplary looped wound
packing sheet of the present invention;
[0028] FIG. 5E is a perspective view of an exemplary velvet wound
packing sheet of the present invention;
[0029] FIG. 6A is a top view of an exemplary spiral corrugated
wound packing sheet of the present invention;
[0030] FIG. 6B is a side view of an exemplary spiral corrugated
wound packing of the present invention;
[0031] FIG. 7 is a perspective view of an exemplary
multi-corrugated wound packing of the present wound packing
invention;
[0032] FIG. 8 is a perspective drawing of an exemplary corkscrew
wound packing of the present invention;
[0033] FIG. 9 is a perspective drawing of an exemplary hollow tube
wound packing of the present invention;
[0034] FIG. 10 is a picture illustrating an exemplary embodiment of
a wound packing material of the present invention;
[0035] FIG. 11 is a picture illustrating a front view of the
exemplary embodiment of FIG. 10;
[0036] FIG. 12 is a picture illustrating a side view of the
exemplary embodiment of FIG. 10;
[0037] FIG. 13 is a picture illustrating a top view of the
exemplary embodiment of FIG. 10;
[0038] FIG. 14A is an illustration representing a wound;
[0039] FIG. 14B is an illustration representing the wound of FIG.
14A with a wound packing of the present invention inserted into the
wound; and
[0040] FIG. 14C is an illustration of the packed wound of FIG. 14C
after suction is applied to the wound.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Nonabsorbent wound packing has an advantage because it
communicates exudates away from the wound and toward a source of
suction more quickly and more completely. A component nonabsorbent
fiber material, for the purposes of wound packing, is one that
absorbs less than about 20% its weight in aqueous liquid. However,
absorbency of a wound packing material is more appropriately
characterized as volume of liquid absorbed by volume of packing (in
its uncompressed state). Thus, a nonabsorbent wound packing
preferably retains less than about one third its volume in aqueous
liquid. More preferably, it retains less than about 11% its volume.
Most preferably, it retains less than about 5% its volume. The
absorbency of a wound packing is a function of a number of physical
properties. Among them are density, wettability of the base
material, the extent to which the base material swells with
absorption, surface characteristics of the individual fibers (if
any), and the geometric organization of the base material that
forms the wound packing.
[0042] Compressibility is a measure of a material's ability to
reduce its volume under compression. A compressible wound packing
permits wound contraction under suction. Generally the wound and
wound packing are sealed with a flexible cover. A suction is then
applied beneath the cover creating a pressure below atmospheric
pressure. The pressure differential between atmospheric pressure
and the pressure at the wound packing creates a compressive force
on the wound packing. A compressible wound packing also adapts to
changes in wound geometry induced by patient movement and wound
contraction so that it continues to conform to wound geometry. The
compressibility of a wound packing is a function of a number of
physical characteristics. Chief among these characteristics is the
proportion of void volume. A high void volume permits the wound
packing to deform in response to a compression force.
[0043] While it is generally advantageous to permit a wound to
contract under suction, it is often preferable to encourage the
wound to contract in one direction in favor of a second and/or
third direction. A material whose response to a compressive force
varies depending upon the direction from which the force is
received is described as anisotropic. In a wound care application,
it may, for example, be preferred to promote contraction of a
wound's "width" while maintaining the wound's length as well as the
wound's depth. Alternatively, it may be desirable to maintain the
relative position of the wound's margins while encouraging healing
from the wound bed.
[0044] Another desirable characteristic of a wound packing is
resiliency. A resilient material resumes its shape and volume after
exposure to compression. A resilient wound packing expands to fill
a wound. This is an advantageous feature because the wound packing
should contact all surfaces of a wound so that wound exudates can
be drawn away from all wound surfaces by suction. Dead spaces
within a wound where no packing is present can fill with wound
exudates that impede wound healing. Further, a resilient wound
packing will discourage overpacking in a clinical setting because
it expands once it is packed into a cavity wound. A resilient
packing also has a beneficial ability to resume its configuration
when suction is stopped and resume or after a patient moves. This
is also important when suction is applied to the wound in an
intermittent fashion.
[0045] It is also generally desirable to use wound packing that
will maintain its integrity such that it does not easily break
apart or degrade and subsequently leave material in a wound.
Materials that demonstrate this quality can be described as
"non-shedding." Non-shedding materials also have the advantage of
being able to be purposely cut to fit an irregular wound without
breaking apart. Materials with a high degree of integrity are
advantageous in that pieces of such materials are much less likely
to break away from the whole and get lodged in the wound bed.
[0046] FIG. 1 illustrates an exemplary embodiment of the present
invention. As shown in FIG. 1, wound packing 100 is a mass of
fibers 101 randomly coupled together. The fibrous mass can take the
form of a simple batting material having a desirable loft.
Alternatively, this batting can be constructed from a single tangle
monofilament material. Wound packing 100 is resilient and
compressible so that it can easily conform to an irregular wound.
Preferably, wound packing 100 is nonwoven. More preferably, wound
packing 100 is spunbonded or melt blown. Component fibers 101 are
comprised of a nonabsorbent synthetic polymer. Examples of suitable
biocompatible materials are polyolefins such as polypropylene and
polyethylene, polyamides such as nylon and related aramids, and
polyester. Additionally, fiber treatments such as hyaluronic acid
or antimicrobial silver may be incorporated into wound packing 100.
Component fibers with one or more of the following beneficial
properties are anticipated. Fibers can be bio-absorbable, they may
be bio-erodable for the controlled release of a curative agent,
they may be adherent for the selective removal of undesirable
tissues, substances or microorganisms or they may be non-adherent
for the protection of delicate tissue. More preferably, the fibers
further incorporate one or more agents recognized in the art to
promote wound healing. For example, calcium alginate fibers can be
incorporated into wound packing 100. Alternatively, fiber
treatments such as hyaluronic acid or antimicrobial silver may be
incorporated into wound packing 100. An embodiment is also
contemplated wherein one or more of the fibers incorporated into
wound packing 100 are sufficiently conductive to transmit a
therapeutic current to the wound tissue from a suitable source (not
shown). An embodiment is also contemplated wherein one or more of
the fibers incorporated into wound packing 100 are sufficiently
conductive to transmit a therapeutic current to the wound tissue
from a suitable source (not shown).
[0047] Because it is composed of nonabsorbent fibers, wound packing
100 is itself substantially nonabsorbent. Non-absorbency is
desirable to minimize retention of wound exudates within the wound
packing 100. The minimized retention has the benefits of reducing
wound exposure to the exudates (and attendant infection) and
lessening the frequency with which the wound packing 100 must be
changed. Wound packing 100 may have some apparent absorbency due to
minor liquid retention via entrapment in the fibrous matrix and
fiber surface adsorption. Alternatively, a controlled proportion of
absorbency can be designed into the packing material 100 to permit
a patient care provider to administer a medicated solution to the
wound area over time by soaking the packing material 100 in the
medicated solution.
[0048] FIG. 2 illustrates another exemplary embodiment of the
present invention. As shown in FIG. 2, wound packing sheet 200
comprises a plurality of nonabsorbent synthetic polymeric fibers
202 randomly coupled together to form a substantially flat sheet
204. Techniques are known in the textile arts that produce random
fibrous materials and include, for example, carding, spunbonding
and melt blowing. An example of a suitable material is the spunbond
polypropylene Typar.RTM. manufactured by BBA Fiberweb.TM. Reemay,
Inc. of Nashville, Tenn. Spunbond polypropylene is beneficial in
that it facilitates the transport of liquids quite effectively.
While wound packing sheet 200 is shown as being substantially flat
it is recognized that it can be further manipulated by means known
in the textile arts to provide substantial thickness. Potential
structures are shown in FIG. 5A as a pleated sheet 210, FIG. 5B as
a contoured sheet 220, and FIG. 5C as an embossed sheet 230.
Further known steps would yield the fabrics with pile depicted in
FIG. 5D and FIG. 5E, as a looped fabric 240 and a velvet fabric
250, respectively. Alternately tufting, as in carpet manufacturing
may be utilized to produce a fabric with pile.
[0049] An exemplary deep tissue wound is illustrated in FIG. 3A. It
comprises a wound cavity 300 suitable for treatment with wound
packing in conjunction with suction. A wound packing is placed into
the wound cavity 300. For example, FIG. 3B depicts wound packing
sheet 200 packed into a wound cavity 300.
[0050] FIG. 4 illustrates an exemplary corrugated unit embodiment
450 of the present invention comprising two sheets. A first sheet
layer 410 is provided, and a second sheet-like layer 420 having an
essentially sinusoidal cross section, for example, is coupled to
the surface of the first sheet layer at locations 430. The coupling
can be achieved by use of an adhesive or heat sealing. A two part
silicone adhesive has been found suitable to provide coupling
between sheet 410 and sheet 420. A bead of silicone material 440
may be optionally added to adjust the resiliency of the corrugated
unit 450. A suitable sheet material is Hollytex.RTM. spunbonded
polyester manufactured by Ahlstrom Corp. of Mt. Holly Springs, Pa.
Hollytex.RTM. is a preferable choice because it is not prone to
fiber shedding. Polyester fibers are preferred for this sheet
because they absorb almost no fluid, transport liquids effectively,
and are creep resistant in that they more readily return to their
original configuration after having a force applied to them for a
period of time. While it is preferable to make a corrugated unit
embodiment from spunbond sheets, other base sheets are suitable as
well. Such sheets may also be made from other nonwoven processes
such as meltblowing or hydroentangling or from regular processes
such as knitting or weaving. Although sheet layer 420 is
illustrated as having a sinusoidal cross-section, the invention is
not so limited. It is also contemplated that other cross-sections,
such as pleated, may be used.
[0051] Corrugated unit 450 can be used as a wound packing without
further modification. It can also be used to form more complex
three-dimensional structures. Spiral wound packing 500 illustrated
in FIGS. 6A and 6B is formed by rolling corrugated unit 450 to
expose a portion of the first flat sheet 410 along the
circumference. More elaborate structures can also be formed from a
plurality of corrugated units. For example, individual corrugated
units may be coupled to each other by adhesive or heat sealing
means to form multi-corrugated wound packing 550. One or more beads
of silicone material 552 can serve dual purposes of coupling the
corrugated units 450, as shown in FIG. 7, and improving the
resiliency of the structure. It should be noted that, while FIG. 7
illustrates this embodiment with the peaks of each adjacent
corrugation unit in alignment, a staggered configuration is also
contemplated. Multi-corrugated wound packing 550 can also be sliced
along a cross section at a suitable thickness to produce cut
corrugated wound packing. Alternatively, wound packing 550 can be
sliced at a bias to produce biased-cut corrugated wound
packing.
[0052] Spiral wound packing 500, cut corrugated wound packing, and
biased-cut corrugated wound packing have the benefit of being
highly compressible and highly resilient. Preferably, these wound
packing structures are sufficiently compressible to reduce to less
than 50% of their original volume when subjected to the
approximately 2 psi (pounds per square inch) compression force
commonly encountered with the application of suction. More
preferably, the wound packing is sufficiently compressible to
reduce to less than 25% of its original volume. Most preferably,
the wound packing is sufficiently compressible to reduce to less
than 10% of its original volume.
[0053] It is desirable for these wound packing structures to be
sufficiently resilient to resume more than 50% of their original
volume after exposure to compressive forces common in a clinical
setting. Such forces can be as high as 20 psi but are more
routinely on the order of 1-2 psi. More preferably, these wound
packing structures are sufficiently resilient to resume more than
80% of their original volume.
[0054] The structure of spiral wound packing 500, cut corrugated
wound packing, and biased-cut corrugated wound packing may also be
varied to more easily compress along one axis than the remaining
two. This may be achieved by varying the angles at which the
corrugated materials are cut or varying the amount and orientation
of the adhesive used during manufacture of the corrugated unit. In
particular, varying the amount and orientation of silicone adhesive
beading has been found to enhance resiliency as well as control or
enhance compressibility in a desired direction. For example,
multi-corrugated wound packing 550 is generally anisotropic, having
a different composite modulus of elasticity for each axis. This
results in a packing that compresses preferentially in certain axes
when vacuum is applied. This attribute is valuable when it is
desirable to encourage the wound to close preferentially in one
direction over another.
[0055] One version of multi-corrugated wound packing 550 has a
modulus of elasticity of 0.9 psi in the x axis, 3.7 psi in the y
axis, and 1.0 psi in the z axis. By way of example, if a 1'' cube
is cut out of multi-corrugated wound packing 550 and a 0.5 lb force
is applied along each axis, the amount of compression in each
direction is as follows; x axis--0.55 inches, y axis--0.16 inches
and z axis--0.5 inches. FIG. 14A illustrates a wound 1400 that
would benefit from an anisotropic wound packing 1410. FIG. 14B
illustrates wound 1400 with an anisotropic packing 1410 prior to
application of suction and FIG. 14C illustrates the wound with a
contracted perimeter during application of suction with anisotropic
packing 1410 in a compressed state. While specific composite moduli
of elasticity are listed for 550, it will be clear to one skilled
in the art that the moduli of elasticity of each axis of a packing
material can be varied to suit a particular need.
[0056] FIG. 8 illustrates an exemplary corkscrew wound packing 600
of the present invention. The corkscrew wound packing can be formed
simply by winding a single continuous sheet if desired. The
spiraling structure of corkscrew wound packing 600 provides a
substantially three dimensional structure with minimal
manufacturing complexity. The spiraling corkscrew structure may be
used as a packing as is or it can be configured with additional
spiraling corkscrew structures to make a more elaborate three
dimensional packing.
[0057] FIG. 9 illustrates an exemplary hollow tubular wound packing
700 of the present invention. Tubular structure 700 can be formed
by a variety of means known in the textile arts. In particular, it
can be formed by braiding component fibers directly into the
desired structure.
[0058] FIG. 10 illustrates another exemplary embodiment of the
present invention. As shown in FIG. 10, wound packing material 1000
has a generally spiral shape exhibiting open areas 1020 along the
longitudinal axis of the fiber spiral and open areas 1040 between
adjacent segments of a particular spiral. Wound packing material
1000 is generally constructed from polymer fibers 1060, such as
spandex.
[0059] To form wound packing material 1000, fibers 1060 are wrapped
around mandrels, such as a steel tube (not shown). The steel tubes
with the spandex wrap are stacked in rows and a polyurethane film
(not shown) is placed between each row. Desirably, the polyurethane
film is about 0.003 inch thick. The stack of tubes is then clamped
together and heated to about 320 degrees F. The polyurethane film
melts and adheres to the spandex fibers, thus coupling the adjacent
spirals to one another. After cooling, the steel tubes are removed.
Wound packing material 1000, as illustrated in FIGS. 10-13
remains.
[0060] Wound packing 1000 benefits from a number of valuable
properties. It is generally nonabsorbent, it is compressible and
resilient such that it rebounds after compression and can be
configured in an anisotropic fashion.
[0061] Additional embodiments are anticipated. A suitable wound
packing can be made by spraying molten filaments on a conveyor with
a waffled surface. A biocompatible binding agent is sprayed onto a
three dimensional form, subsequently a chopper gun is used to spray
chopped fibers with the desired properties onto the form. The
binding agent serves to couple the fibers together forming an
appropriate wound packing.
[0062] While preferred embodiments of the invention have been shown
and described herein, it will be understood that such embodiments
are provided by way of example only. Numerous variations, changes
and substitutions will occur to those skilled in the art without
departing from the spirit of the invention. Accordingly, it is
intended that the appended claims cover all such variations as fall
within the spirit and scope of the invention.
* * * * *