U.S. patent application number 11/972854 was filed with the patent office on 2008-05-08 for method for treating wound, dressing for use therewith and apparatus and system for fabricating dressing.
Invention is credited to Dmitriy SINYAGIN.
Application Number | 20080108927 11/972854 |
Document ID | / |
Family ID | 29420421 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080108927 |
Kind Code |
A1 |
SINYAGIN; Dmitriy |
May 8, 2008 |
Method For Treating Wound, Dressing For Use Therewith And Apparatus
and System for Fabricating Dressing
Abstract
A method of treating a wound using a customized dressing. In the
method, at least one wound characteristic is evaluated. A treatment
need as a function of the at least one wound characteristic is
determined. A dressing having a dressing characteristic responsive
to the treatment need is fabricated and applied to the wound. A
dressing for use therewith and an apparatus and system for
fabricating the dressing are provided.
Inventors: |
SINYAGIN; Dmitriy; (San
Carlos, CA) |
Correspondence
Address: |
MACPHERSON KWOK CHEN & HEID LLP
2033 GATEWAY PLACE
SUITE 400
SAN JOSE
CA
95110
US
|
Family ID: |
29420421 |
Appl. No.: |
11/972854 |
Filed: |
January 11, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10431888 |
May 7, 2003 |
|
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11972854 |
Jan 11, 2008 |
|
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60378635 |
May 7, 2002 |
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Current U.S.
Class: |
602/54 ;
602/42 |
Current CPC
Class: |
A61F 2013/00574
20130101; A61F 2013/00174 20130101; A61F 2013/0054 20130101; D01D
5/0007 20130101; G16H 70/20 20180101; A61F 13/00068 20130101; Y10S
706/924 20130101; A61F 13/00987 20130101; Y10S 602/90 20130101;
Y10T 29/49 20150115; A61F 13/00063 20130101; A61F 2013/8488
20130101; G16H 50/20 20180101; A61F 2013/00221 20130101; A61F
2013/00927 20130101; G16H 30/20 20180101; A61F 2013/00536
20130101 |
Class at
Publication: |
602/054 ;
602/042 |
International
Class: |
A61F 13/02 20060101
A61F013/02 |
Claims
1-12. (canceled)
13: A dressing for treating a patient having a wound with at least
first and second contiguous regions surrounded by skin, the
dressing comprising a first portion made from a first material
adapted for engaging the first region of the wound and a second
portion made from a second material different than the first
material adapted for engaging the second region of the wound.
14: The dressing of claim 13 further including an adhesive layer
for adhering the dressing to the skin of the patient, wherein the
adhesive layer extends around the first and second portions.
15: The dressing of claim 13 wherein the second portion extends
around the first portion.
16: The dressing of claim 13 wherein the first portion has a first
thickness and the second portion has a second thickness.
17: The dressing of claim 13 wherein the first portion includes a
first layer for engaging the first region of the wound and an
overlying second layer, the second layer extending beyond the first
portion and engaging the second region of the wound.
18: The dressing of claim 13 wherein the dressing further includes
a third portion made from a third material different from the first
and second materials.
19-22. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. provisional patent
application No. 60/378,635 filed May 7, 2002, the entire content of
which is incorporated herein by this reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to wound treatment
and systems and methods of preparing a wound dressing. More
particularly, it relates to a wound treatment including a dressing
adapted to match the wound site.
BACKGROUND OF THE INVENTION
[0003] Currently, the common method of wound treatment is to cover
the wound with a wound dressing. The wound dressing is manufactured
as a precut sheet of multi-layer material of various shapes and
sizes. The wound dressing is applied to cover the wound and a
portion of the surrounding healthy skin. Sometimes the wound
dressing is cut to reduce the size and to better fit the wound size
and shape. This reduces the amount of healthy skin covered by the
dressing.
[0004] A typical wound commonly has two or more regions or areas,
including necrotic, sloughy, bacteria colonized, granulating,
epitheliazing, bleeding, exudating, and drying. An exemplary wound
10 has a granulating area 12 having heavy exudates and an
epitheliazing area 14 having low exudates, which are surrounded by
healthy skin tissue 16 (see FIG. 1). The wound 10 and its areas 12,
14 are usually of irregular shapes. The areas 12 and 14 of the
wound 10 typically differ from each other by healing stage, depth,
contamination, infection, and tissue stress due to patient body
movement. Consequently, covering the whole wound area and
surrounding healthy skin with the same dressing type may create
adverse conditions for certain areas of the wound or the
surrounding skin, which may increase the healing time or even cause
adverse effects such as secondary dermatitis.
[0005] Accordingly, there is a need in the art for a method for
wound care that provides the optimal conditions for wound healing
by matching the size, shape, and material properties of a wound
dressing to the wound area. There is a further need for a system to
produce such a wound dressing.
SUMMARY OF THE INVENTION
[0006] According to one embodiment of the invention, a method of
treating a wound using a customized dressing is provided. In the
method, at least one wound characteristic is evaluated. A treatment
need as a function of the at least one wound characteristic is
determined. A dressing having a dressing characteristic responsive
to the treatment need is fabricated and applied to the wound. A
dressing for use therewith and an apparatus and system for
fabricating the dressing are provided.
[0007] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various obvious aspects, all without departing from the spirit and
scope of the present invention. Accordingly, the drawings and
description are to be regarded as illustrative in nature and not
restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The accompanying drawings, which are somewhat schematic in
many instances and are incorporated in and form a part of this
specification, illustrate exemplary embodiments of the invention
and, together with the description, serve to explain the principles
of the invention.
[0009] FIG. 1 is an isometric view of a typical wound.
[0010] FIG. 2 is an isometric view of a wound covered with a wound
dressing according to one embodiment of the present invention.
[0011] FIG. 3 is a sectional view of the wound dressing taken along
the line 3-3 in FIG. 2.
[0012] FIG. 4 is a flow chart showing a method of treating a wound
using a wound dressing according to one embodiment of the present
invention.
[0013] FIG. 5 is a schematic view of a wound dressing fabrication
system according to one embodiment of the present invention.
[0014] FIGS. 6A and 6B are flow charts illustrating the steps
performed by the processor of the system shown in FIG. 5, according
to various embodiments of the invention.
[0015] FIG. 7 is schematic view of a portion of a wound dressing
fabrication device.
[0016] FIG. 8 is an isometric view of a device for fabricating a
wound dressing according to one embodiment of the present
invention.
[0017] FIG. 9 is a partial isometric view the device of FIG. 8.
DESCRIPTION OF THE INVENTION
[0018] A wound 20 is covered by an adapted or customized wound
dressing 22 (see FIG. 2). The wound dressing 22 may include two or
more regions or layers. Each region or layer is customized to match
a size and shape of the wound (see FIGS. 2 and 3). It is further
customized to address one or more wound healing needs. In one
embodiment, the wound dressing 22 includes a first region 26,
second region 28, and a backing film 30 (see FIG. 3). The first
region 26 of the wound dressing 22 is located generally near a
center of the wound dressing 22 and is sized and shaped to
generally match or engage the first (e.g., granulating) area 12 of
the wound 20. The second region 28 of the wound dressing 22
surrounds the first region 26 and is sized and shaped to generally
match or engage the second (e.g., epitheliazing) area 14 of the
wound 20.
[0019] The first and second regions 26 and 28 are typically
contiguous to match the contiguous first and second areas 12, 14 of
the wound 20. The backing film 30 is positioned on top of the first
region 26 and the second region 28 and extends radially outward
from the second region 28. The exposed surface of the backing film
30 generally corresponds to the healthy skin surrounding the wound
20. In another embodiment, the wound dressing 22 includes only one
of the first region 26, and the second region 28, in combination
with the backing film 30. In one embodiment, the first region 26 in
the second region 28 include multiple layers of material having
differing material properties.
[0020] The present invention, according to one embodiment, is a
method 40 for treating a wound on a patient using the adapted or
customized wound dressing 22 (see FIG. 4). In general terms, the
method includes evaluating a set of wound characteristics (block
42), defining the properties of a wound dressing based on the wound
characteristics (block 44), fabricating the wound dressing (block
46), and applying the wound dressing to the wound (block 48).
[0021] Evaluating the characteristics of the wound may be conducted
in various ways. The wound characteristics are evaluated and
defined in at least two dimensions. In one embodiment, the
characteristics are evaluated in three dimensions. Wound
characteristics evaluated may include one or more of type of wound,
amount of exudate, size, shape, depth, advancement level, bacteria
colonization, epitheliazation, sensitivity, severity, health of
surrounding skin, periwound properties, and pain level. Wound
characteristics may also include one or more of, or the user may
use the following, wound severity, the width, length, depth,
tunneling, base color of the wound compared to the surrounding skin
color, the condition of the wound edge, amount of necrosis, type of
exudate, color of exudate, odor of exudate, condition of the
periwound area, color or the periwound area, edemic qualities of
the periwound area, induration, and granulation. Any other
characteristic of the wound can also be evaluated and used to
define the attributes of the wound dressing. The wound types may
include, for example, burn, cut, ulcer, and abrasion. The exudates
may include, for example, none, low, medium, and heavy. Each of the
wound characteristics may be evaluated and categorized based on any
desired system.
[0022] In one embodiment, the evaluation includes generating a two-
or three-dimensional map of the characteristics of the wound area.
The map may be presented in the form of coordinated points or areas
of measured size or coordinated relative to each other or to a
common origin point. The coordinates of the local points or areas
of the wound may be measured by ruler or digitized using any
technique known in the art, including a digital camera or various
types of two- or three-dimensional scanners. This map generation
process be performed manually by a person or automatically using
computer recognition or analytical tools (e.g., chemical,
biological, moisture, probing, optical (including UV or IR), or
gas), or by some combination thereof. After the mapping technique
is specified, the desired wound characteristics or properties are
measured for each point in the map. This map may, for example, be
stored in a data array including a column specifying the location
in the wound and a set of additional columns including data
representing each evaluated wound characteristic. The use of
discrete data points would facilitate the use of pattern
recognition algorithms, as well as tree analysis.
[0023] The evaluation process, in one embodiment, also includes an
evaluation of certain characteristics of the patient. These patient
characteristics may include those characteristics that could affect
the success of a treatment routine for the type and severity of the
wound. For examples, these characteristics may include allergies,
health or immune problems, topography of the body part on which the
wound lies, and a color of the surrounding healthy skin.
[0024] In one embodiment, the characteristics of the wound dressing
are determined solely based on the size and shape of the areas or
regions of the wound. In this embodiment, the dimensions of the
wound dressing are set to match size, shape, and depth of the wound
area. The materials that the wound dressing is fabricated from are
determined by the region of the wound to which the material
corresponds in another embodiment, the materials from which the
wound dressing is fabricated from are further determined by the
additional wound characteristics. In yet another embodiment, the
materials from which the wound dressing is fabricated are further
determined by the patient characteristics.
[0025] The defined wound dressing properties or characteristics may
include physical, chemical, geometrical, optical, electrical,
number of layers, porosity of a layer, thickness, and any other.
The determined or assigned characteristics of the wound dressing
may include adsorbing capacity, water penetration capacity, water
vapor penetration capacity, gas penetration capacity, thickness,
material, material form (e.g., continuous film or fiber), number of
layers, pharmacological or healing enhancing additives, color,
local absence of dressing, and adhesive.
[0026] Other characteristics important to the healing process may
also be assigned. In other words, based on the wound
characteristics, a wound treatment need is determined. For example,
a wound having high exudate areas requires a high absorbing and
high water evaporation material dressing property. Areas having low
exudates and epitheliazing wound areas require low absorbing with
limited water permeability material dressing property to keep wound
moist environment. The healthy skin area around the wound may be
used for the wound dressing attachment with, as an example, medical
adhesive. Also, the portion of the wound dressing corresponding to
healthy skin must be breathable and suitable for holding an
adhesive. This portion of the dressing, for example, may be a
porous films or fiber web that is completely permeable for
gas/vapor but provides mechanical support for the dressing and
attachment to the health skin.
[0027] The wound dressing is fabricated once the dimensions and
materials of the wound dressing are determined. Fabrication is
performed using any known wound dressing fabrication technique.
[0028] In one embodiment, at least one wound dressing layer is made
from polymer fibers. The layer is fabricated by electro-spinning or
gas blowing of a polymer solution or melted for localized
deposition onto the wound, the support, or underlying dressing
layers, according to the wound dressing parameter map. The fibers
may have a diameter of from about 0.01 to about 50 microns,
depending on chosen parameters of the deposition process.
[0029] In one embodiment, the outer layer of the dressing is made
from a continuous polymer film. This film may be porous with a pore
size small enough to prevent penetration of dust, aerosol, and
bacteria. The pore size, in one embodiment, may be from about 0.01
to about 1 micron. The film is made of or coated by an at least
partially-hydrophilic polymer. The film thickness is chosen to
provide mechanical strength and support to the dressing during
transfer from the support and application on the wound. The film
thickness, in one embodiment, may be in the range of from about 5
to about 100 microns.
[0030] The method for deposition of the porous film may be one of
the following: pressure or jet spray, ultrasonic spray,
electrodynamic spray in an electrostatic field, droplet placement,
and solution or melt dispensing. The film thickness and pore size
are controlled by material flow rate, size of droplets during
spray, velocity of the droplets colliding with the support,
electrostatic field strength, relative velocity of the support
movement or dwelling time at the certain point of the dressing,
number of passes over the certain point, overlapping of other
deposition areas, temperature of the droplets and the support.
[0031] A medical adhesive may be applied to areas of the outer
layer of the wound dressing extending beyond the area of the wound
to assist in attaching the wound dressing to the skin. In this
embodiment, the wound dressing map is extended beyond the wound
area so that the outer layer with the adhesive corresponds to
available healthy skin areas. The wound dressing parameter map may
be made so that the wound dressing layer extending beyond the wound
area forms strips or ribbon, to be used for wrapping around the
patient body (e.g., hand, foot, leg, or finger) for convenient and
reliable wound dressing placement and attachment. This may
eliminate the need for secondary dressings and attachment enforcing
means (e.g., sticky tape, elastic gauze, and compressive wraps).
The thickness of these areas may be increased to provide additional
strength for compressive dressing application. The strips or
ribbons may be designed in the map to include locking features such
as loops or hooks. Likewise, the wound dressing parameter map may
be developed so that at least one dressing layer is provided with
thickened strips or any form grid to provide expansion strength to
the dressing for compression application.
[0032] One embodiment of the present invention is a computer-based
system 50 for evaluating the wound 20, creating a map of wound
properties or characteristics, and fabricating and adapted or
customized wound dressing 22. In one embodiment, the system 50
includes a digital imaging device 52, a computer or processor 54,
and a wound dressing fabrication system 56 (see FIG. 5).
[0033] The digital imaging device 52 may be any digital imaging
device known in the art, including a digital camera and a digital
scanning device. For example, the digital imaging device may be the
RAINBOW 3D camera marketed by Genex Technologies, Inc. of
Kensington, Md. The digital imaging device 52 is used to generate a
digital image of the wound and the surrounding tissue. In one
embodiment, the device 52 is used to produce a digital image of the
entire body part on which the wound is located. In one embodiment,
the system 50 does not include a digital imaging device 52. In this
embodiment, the characteristics and dimensions of the wound
dressing are specified solely based on information provided by a
user of the system 50.
[0034] The computer or processor 54 is programmed with a software
program for receiving characteristics or attributes of the wound 20
and creating a wound dressing map for output to the fabrication
system 56. The processor 54 may be programmed with various
algorithms, depending upon the needs of a user. In one embodiment,
the processor 54 performs a first algorithm 60 (see FIG. 6A). This
first algorithm 60 includes receiving a digital image from the
digital imaging device (block 62), requesting and receiving wound
characteristics as specified by a user (block 64), determining a
size and shape of the wound, based on the digital image and the
wound characteristics (block 66), and generating a wound dressing
specification, based on the size and shape of the moment, and
sending the specification to a wound dressing fabrication device
(block 68).
[0035] In another embodiment, the processor 54 performs a second
algorithm 70 (see FIG. 6B). This second algorithm 70 includes
receiving a digital image from the digital imaging device (block
72), requesting and receiving wound characteristics as specified by
the user (block 74), requesting and receiving patient
characteristics as specified by a user (block 76), determining a
size and shape of the wound, based on the digital image and the
wound characteristics (block 78), determining healing needs of the
wound, based on the digital image in the wound characteristics
(block any), generating a wound dressing specification and sending
the specification to a fabrication device (block 82).
[0036] In this embodiment, the software program may receives input
data concerning any diseases and allergies suffered by the patient.
The software program then flags, or issues output alarms if
appropriate, patient characteristics that could affect treatment of
a wound having the type and severity previously determined by the
software program. In one embodiment, the patient data is taken from
an electronic file containing the patient's medical history.
[0037] In one embodiment, the user chooses desired properties of
the dressing for at least some points or zones of the wound
characteristic map. This choice may be based on user knowledge of
wound healing process or procedures and recommendations available
by the time to provide optimal healing conditions for the certain
wound areas. The user may also optionally expand the desired
dressing properties area (and correspondingly the map) on
surrounding healthy skin, for example, for sealing the wound or
dressing attachment with a medical adhesive or for protective,
cosmetic, marking, aesthetic, and any other purpose. For example,
in one embodiment, an outer layer of the dressing may colored or
patterned for marking or to match the patient's healthy skin
color.
[0038] Based on the desired dressing properties map, the user
creates a map of dressing properties. As described above, the
dressing properties may be physical, chemical, geometrical,
pharmacological, biological, optical, electrical, number of layers,
porosity of a layer, thickness, and any other. The combination of
these parameters at any given point or location of the dressing,
define the desired dressing properties map. In one embodiment, the
definition of the dressing properties map is done by the user
manually. In one embodiment, for example, the user assesses a wound
shape (e.g., round, elliptical, triangular, rectangular,
trapezoidal, rhomboidal, and narrow strip) and chooses a closest
shape from a library of predetermined shapes stored within the
processor 54. This may be done for the whole wound or for some
areas of the wound and the surrounding skin. The user defines
characteristic dimensions of the chosen shape in accordance with
the real dimensions of the wound or wound areas. Then the shapes
are combined together with coordinated overlapping of these shapes
to define the shape of the entire wound area.
[0039] In another embodiment, the wound dressing specification or
properties map is generated by the processor executing software in
automatic or semi-automatic mode, using predetermined
experimentally or theoretically dependence of the resulting
properties of the dressing on the dressing parameters. If a
three-dimensional digitizer or scanner was used for
three-dimensional wound or patient body mapping, the image may be
flattened to create a two-dimensional wound map and corresponding
dressing properties maps.
[0040] In another embodiment, characteristics of the wound dressing
are determined by comparing wound or patient characteristics to a
data set, such as a look-up table, to determine a desired dressing
characteristics. The patient characteristics and wound
characteristics may be compared to a library of wound dressings
properties to generate a selection of proposed wound dressings
properties that support the treatment needs or goals.
[0041] For a wound dressing including several layers, a separate
dressing parameter map may be created for each layer so that the
overlapping of the layers and their properties provides the
resulting local dressing properties in correspondence with the
desired dressing properties map.
[0042] The fabrication system 56 uses the dressing parameter map
for fabrication of the wound dressing. The fabrication system 56
fabricates the dressing with the characteristics or properties
specified by the dressing properties map. In one embodiment, for
example, these characteristics include the material, the
dimensions, and pharmacological additives.
[0043] Proper materials are used in correspondence with the
dressing parameter map. Exemplary materials that may be used
include polymers (synthetic or natural), biomaterials,
pharmacological additives, water, hydrogel or hydrocolloid,
adhesives, paints, and fragrances. Any other material that would
enhance healing of the wound may also be used in the wound
dressing. The selection of an appropriate dressing material for
each location within the parameter map may be manually selected by
a user, or automatically selected by the processor 54. In one
embodiment, for example, the processor 54 selects the material
based on the amount of exudate. If the amount of exudate is high,
the processor 54 selects the material having a high absorbency. For
example, the inner wound dressing layer that will contact the wound
may be made from bioabsorbable polymer fibers, including
bioabsorbable polymer fibers that are self adherent to a wet wound.
If, on the other hand, the amount of exudate is low, the processor
54 may select a moisturizing material. For example, an inner wound
dressing layer that will contact the wound may be made from
hydrogel having a high concentration of distilled water.
[0044] A proper material deposition or application method is used
to fabricate the shape or form of the material at every point or
area specified in the dressing parameter map. The fabrication
methods may include, for example, spraying of polymer solution or
melt (with or without electrostatic field or gas flow assistance),
jet deposition, dispensing, and any other known or to be invented
methods of controllable localized material deposition. Such
parameters as the material delivery rate, dwelling time, material
temperature, electrical or magnetic field strength and polarity,
incident angle, substrate temperature, ambient pressure,
temperature and gas or liquid composition, radiation, distance
between the material source and the deposition place and any other
may be used to meet the requirements of the dressing parameter map.
In one embodiment, the dressing is built layer-by-layer using
localized material deposition in correspondence with a parameter
map for every layer.
[0045] The needed thickness of the wound dressing or at least
particular layer may be achieved by corresponding variation of the
dwelling time over the given point or area, or by variation of the
material delivery rate, or by combination of the both methods. The
dressing layers may be made by deposition of a substantially
homogeneous mixture of any of a variety of hydrophilic and at least
weakly hydrophobic polymers, which may be blended with any of a
number of medically important wound treatments, including
analgesics and other pharmaceutical or therapeutic additives.
Materials to fabricate the wound dressing may be in solid-state
form and melted, softened, dissolved, mixed, or powdered before
and/or during and after deposition.
[0046] Such polymeric materials suitable for forming microfibers
may include, for example, those inert polymeric substances that are
absorbable and/or biodegradable, that react well with selected
organic or aqueous solvents, or that dry quickly. Essentially any
organic or aqueous soluble polymer or any dispersions of such
polymer with a soluble or insoluble additive suitable for topical
therapeutic treatment of a wound or for skin treatment or
protection may be employed. Examples of suitable hydrophilic
polymers include, but are not limited to, linear
poly(ethylenimine), cellulose acetate and other grafted celluloses,
poly (hydroxyethylmethacrylate), poly (ethylene oxide), and poly
vinylpyrrolidone. Examples of suitable polymers that are at least
weakly hydrophobic include such as, poly(caprolactone),
poly(D,L-lactic acid), poly (glycolic acid), similar co-polymers of
theses acids. The present invention provides a method of depositing
films or fibers on a surface for other therapeutic or cosmetic
reasons, which comprises using the mixture with a biocompatible
polymer which may be bioabsorbable or biodegradable polymer such as
polylactic acid, polygylcolic acid, polyvinyl alcohol or
polyhydroxybutyric acid. Ratio of polymer to solvent in the mixture
may vary from 90:10% to 30:70%. Electro conductivity of the mixture
may be in the range from 104 to 1010 Ohm/cm.
[0047] In one embodiment, other additives, either soluble or
insoluble, may also be separately applied or included in the
mixtures to be incorporated into the dressing films or fibers.
These additives may include medically-important topical additives
provided in at least therapeutically-effective amounts for the
treatment of the patient or for a skin treatment or protection.
Such amounts depend greatly on the type of additive and the
physical characteristics of the wound as well as the patient.
Examples of such therapeutic and other additives include, but are
not limited to, antimicrobial additives such as silver-containing
agents, iodine and antimicrobial polypeptides, analgesics such as
lidocaine, soluble or insoluble antibiotics such as neomycin,
thrombogenic compounds, nitric oxide releasing compounds such as
sydnonimines and NO-complexes that promote wound healing, other
antibiotic compounds, bactericidal or bacteriostatic compounds,
fungicidal compounds, analgesic compounds, other pharmaceutical
compounds, fragrances, odor absorbing compounds, and nucleic acids.
The additives may also include vitamins, antioxidants, insect and
animal repellent, dye, paints, ink, UV, visible, and infrared
absorbing and/or reflecting additives, cosmetic additives, paints
for fiber coloring, and adhesives. Also, additives for hair
treatment, removal, extension, volumizing, protection, coloring,
restoration; tattoo and skin defect covering, discoloration, or
removal; and skin rejuvenation.
[0048] Materials formed of two or more components which have only a
short-shelf life when mixed together may be formed in a timely
manner using a method embodying the present invention by
encapsulating the respective components in respective fibers,
particles or microcapsules so that mixing of the various components
only occurs when the components are released from the encapsulating
material by, for example, leaching through the encapsulating
material, rupture by pressure being applied to the encapsulating
material, temperature, or degradation, for example bioabsorption or
biodegradation, of the encapsulant. Such a method may be used to
form, for example, two component adhesives that may be applied
separately or simultaneously to a surface as fibers, particles or
microcapsules by a method embodying the invention.
[0049] The wound dressing fabrication may be done directly on the
wound. In this case the dressing parameter map is coordinated and
oriented according to the physical position and orientation of the
patient body part to be dressed. The system for dressing
fabrication may be provided with means for patient body part
immobilization. The system may be provided with means to detect the
instantaneous position or orientation of the patient body part by
optical or X-ray or any other means, and correspondingly provide
proper orientation and positioning of the tools for dressing
fabrication relative the wound.
[0050] The wound dressing fabrication may be done on a support and
then transferred onto the wound. The dressing and the wound are
properly positioned and oriented relatively to each other to
provide acceptably exact application of the wound dressing on the
wound. The application may be done manually by the patient, medical
personnel or automatically or semi-automatically by a manipulator
or robot.
[0051] A method and device embodying the invention may also be used
for non-medical or skin treatment purposes. For example, coatings
of fibers, particles or microcapsules maybe formed on substrates
such as paper with good control of the thickness and uniformity of
the coating. For example, adhesive may be deposited onto a
substrate using a method embodying the invention.
[0052] A fabrication device 56 for fabricating the wound dressing
22, according to one embodiment of the invention, includes a
localized material deposition source 62, a stage or support 64, and
an actuation system 66 (see FIG. 7). The wound dressing 22 is
formed on the support 64, by directing material from the deposition
source 62 onto the support 64. The actuation system 66 operates to
position the support 64, based on the specified wound dressing
properties.
[0053] The device 56 may be provided with enclosure for sterile and
protected dressing manufacturing. The device 56 may be provided
with means to sterilize the dressing and internal volume of the
system by elevated temperature, irradiation, ultra-violet, or gas
for bacteria, spore and microbe elimination. The device 56 may be
provided with a sub-system for gas or air recirculation to keep
clean and sterile environment with controlled humidity, elimination
of solvent vapor or other by-products of material deposition, or
ozonating air for sterility. The system interior or the stage may
be kept under elevated temperature for sterility or assisting wound
dressing fabrication. The system internal volume may be kept under
pressure that is higher than ambient atmospheric pressure outside
the system to prevent interior contamination by outside air. In one
embodiment, the device 56 includes an internal vacuum chamber for
dressing fabrication under vacuum or dressing drying or degassing
after fabrication.
[0054] The deposition source 62 includes a reservoir or cartridge
70 filled with a material 72. The material 72 may be any
appropriate material specified by using any of the techniques
described above. The material may be in solid, liquid, gel, powder,
granule or any other state, or it may be a mixture of different
states. The cartridge 70 includes a capillary or outlet 73. The
deposition source 62 is held in place by the mounting fixture, 74.
The deposition source 62 operates by pushing an actuator 75, which
forces the material 72 out of the cartridge 70 through the
capillary 73, using any technique known in the art. For example,
the actuator 75 may be a piston. The cartridge 70 or the capillary
73, may include a device for controlling a temperature of the
structures or of the material 72, such that the material 72 has a
temperature that is required by the deposition process. For
example, if the material 72 is a powder then it reaches melting
temperature upon exiting the capillary 13, as a liquid melt. In one
embodiment, the cartridge 70 and capillary 73 are made of
electrically conductive material and may be isolated from the
mounting fixture 74. An electrical potential may be applied to the
capillary 73 or it may be grounded. The mounting fixture 74 may be
made of conductive material and held under electrical potential. In
one embodiment, the capillary 73 is located from about 0.02 to
about 25 cm from the support 64 and faces a deposition surface of
the support 64 onto which the wound dressing 22 is fabricated. The
internal diameter of the capillary 73, in one embodiment, may be
from about 0.1 to about 10 mm. In one embodiment, the deposition
source 62 includes two or more cartridges 72 containing different
materials 72.
[0055] The localized material deposition sources may be any known
or to be invented devices that may include, but not limited to,
spraying of polymer solution or melt with or without electrostatic
field or gas flow assistance, jet deposition, droplet or continuous
material placement and dispensing, and any other known or to be
invented methods of controllable localized material deposition. In
one embodiment, the droplet size is in the range of from about 0.01
to about 50 microns, the fiber thickness is in the range of from
about 0.01 to about 20 microns. In one embodiment, the deposition
area is controllably changed from about 1 to about 300
mm.sup.2.
[0056] The support 64 may be selected to provide for low adhesion
to the dressing material, including a medical adhesive if it is
used for dressing fabrication. In one embodiment, the support 64
forms a part of the final dressing 22. For example, it may provide
mechanical rigidity for the dressing to keep the shape, or it may
provide support or additional mechanical protection for the wound
(to ease the pressure or prevent tissue moving). In other
embodiments, the support 64 is a separate component from the
dressing 22. In these embodiments the support 64, may serve as part
of the packaging over may be discarded after fabrication of the
dressing 22. The support for wound dressing fabrication may have a
three-dimensional topography that reproduces the patient body
three-dimensional topography. That allows manufacturing a wound
dressing that fits three-dimensional topographies of the wound or
patient body. The stage or support 64 may be include heating or
cooling elements to control a temperature during deposition of
dressing materials, or for processing after dressing
fabrication.
[0057] The support 64 may be made as a thin film or plate. It may
have lateral dimensions larger than those of the dressing 22. In
one embodiment, the thickness of the support 64 is in the range of
from about 10 microns to about 2 mm.
[0058] The actuation system 66 includes components for positioning
the support 64, relative to the deposition source 62. The actuation
system 66 may include components for either two or
three-dimensional movement of the support 64 (or the deposition
source 62). In one embodiment, the actuation system 66 includes a
computer or processor 76, a first linear actuator 78 and a second
linear actuator 80. The first linear actuator 78 is coupled to the
support 64 and the second linear actuator 80 is coupled to a
movable platform 82. The movable platform 82 supports a first lower
electrode 84. In one embodiment, the first lower electrode 84 is
surrounded on either side with a dielectric material 86 and a
second lower electrode 88. The second lower electrode 88 may also
be surrounded by an additional dielectric material followed by yet
another electrode, and so on. The first lower electrode 84 is
positioned on the opposite side of the support 64 as the capillary
73. The tip of the first lower electrode 84 may be located close to
the support 64, or may touch the surface of the support 64. The tip
of the first lower electrode 84 may be made rounded and coated with
a material for low friction. The second (and any following)
electrode tips may be located close to the support 64 or may even
touch the surface of the support 64. The tips of these electrodes
may be rounded and may be coated with a material for low
friction.
[0059] The first linear actuator 78 is coupled to the support 64,
such that it causes translation of the support 64 and either an "x"
(to the left or right is shown in FIG. 7) or a "y" (Intuit out of
the page as shown in figure seven) direction. In one embodiment,
two actuators are coupled to the support 64 to cause motion in both
directions. Likewise, the second linear actuator 80 is coupled to
the movable platform 82, such that it causes translation and either
in the "x" or the "y" directions. In one embodiment, two actuators
are coupled to the movable platform 82 to cause motion in both
directions.
[0060] The controller 76 actuates the linear actuator 78 to control
position and speed of the support 64 relative to the deposition
source 62 according to the wound dressing parameter map. The
controller also actuates the linear actuator 80 to control the
position in speed of the electrodes 84, 88, relative to the
deposition source 62. Using a combined motion of the support 64 and
the movable platform 82, the controller can control the position on
the support 64 that the material 72 impacts. For example, the
controller might control the linear actuator 78 to effect motion in
the "x" direction, and control the linear actuator 80 to effect
motion in the "y" direction. In another embodiment, for example,
one of the support 64 and the movable platform 82 may be fixed, and
the other may be used to accomplish motion in both directions. If
the support 64 includes actuators for effecting two-dimensional
controlled movement along its plane, the first lower electrode 84
may be installed along the line perpendicular to the support 64
surface and originating in the center of the outlet of the
capillary 73. The velocity of the first lower electrode 84 may be
in the range of from about 0 to about 100 m/sec for thin and porous
films.
[0061] Other actuation mechanisms known in the art may also be used
in the system 56 to effect motion of the support 64 and the movable
platform 82. In one embodiment the total relative motion between
movable member platform 82 and the support 64 is in the range of
from about one to about 400 mm.
[0062] The controller 76 also operates to turn activate the
deposition source 62 and to control deposition conditions,
developed for the particular deposition method, according to the
wound dressing properties map.
[0063] In one embodiment, the device 56 further includes a third
dimension actuator for controlling movement in a third dimension.
This actuator may be used for fabricating three-dimensional
topography of the dressing, or providing optimal conditions for a
specific material deposition method, which may differ for different
deposition techniques.
[0064] During operation, the system 56, such parameters as the
material delivery rate, dwell time, material temperature,
electrical or magnetic field strength and polarity, incident angle,
substrate temperature, ambient pressure, temperature and gas or
liquid composition, radiation, distance between the material source
and the deposition place and any other may be used to fabricate a
dressing 22 having the properties specified in the dressing
properties map. The dressing may be fabricated layer-by-layer using
proper relative motion of the support 64 and the deposition sources
62 controlled in correspondence with the dressing properties map
for each layer. The thickness of the wound dressing or at least a
particular layer may be controlled by a variation of the dwelling
time over the given point or area while the proper material
delivery source is on, a variation of the material delivery rate,
or by a combination of both methods.
[0065] To accomplish deposition of the material 72 from the
deposition source 62 onto the support 64, an electrical potential
is implying between the capillary 73 and the first lower electrode
84, such that the electrical field strength between them in range
from about 0.1 to about 10 kV/cm. If the support 64 is made of
non-electrically conductive material, the shape and size of the
first lower electrode 84 is chosen according to the accuracy of
material deposition requirements. The diameter of the first lower
electrode may be in range from 0.1 to 100 mm. The second lower
electrodes 88 and other additional electrodes may also be
electrically connected to a sources of electrical potential
relative the capillary 73. These additional electrodes may be
placed between the capillary 12 and support 16.
[0066] According to one embodiment, the system 56 operates as
follows. The material 72 is forced out through the capillary 73
with a flow rate of from about 0.01 to about 50 ml/min. The
material 72 is pulled by the electrical field, applied between the
capillary 73 and the electrodes 84, 88, and accelerated toward the
first lower electrode 84, because of the material 72 is carrying an
electrical charge. Depending on the material flow rate, material
viscosity, polymer molecular mass, and the electric field strength,
the material 72 is reaching the surface of the support 64 in the
form of a jet, a flow of droplets or microfibers. Copending U.S.
patent application Ser. No. 10/382,422, filed Mar. 5, 2003,
entitled "Method and Apparatus for Forming a Microfiber Coating,"
which is hereby incorporated by reference in its entirety,
discloses one system that could be used as the device 56 for
fabricating the wound dressing.
[0067] The size of the deposition spot is defined by the size of
the first lower electrode 84 and electrostatic repelling of the
droplets or micro-fibers from each other. The deposition spot size
may be controlled by the potential, polarity, and positioning of
the second lower electrodes 88 and any additional electrodes. The
closer the potential of the second lower electrodes 88 and any
additional electrodes to the potential of the first lower electrode
84, the wider the deposition zone. If the potential of the second
lower electrodes 88 and any additional electrodes is close to the
potential of the capillary 73, the material deposition will be more
concentrated over the first lower electrode 84. The type and
thickness of the dielectric 86 is chosen to prevent the electrical
breakdown between the electrodes. In various embodiments, the
dielectric may be Teflon or ceramic.
[0068] Moving the support 64 relative the capillary 73, the second
electrode 17, or both, leaves a trace of deposited material on the
surface of the support 64. A continuous layer of material may be
achieved by proper two-dimensional scanning and overlapping the
scans or traces of the deposited materials. If the dressing layer
is made by several consequent passes over the same area then the
overlapping may be optimized experimentally with a few simple
measurements of thickness uniformity over the resulting layer.
[0069] Controllable motion of the first lower electrode 84 caused
deflection of the flow of material so that the material deposition
spot is moved along the surface of the support 64 without moving
the support 64. The deflection may reach about 40 degrees from the
perpendicular to the surface of support 64. The morphology of the
deposited layer may be changed due to incident angle change so the
acceptance of the resulting layer properties has to be checked
experimentally. The material flow rate and electrical field
strength may be changed as a function of angular position of the
first lower electrode 84 to partially compensate for the material
travel time variations and, possibly, properties of the material
upon reaching the surface. The larger the angular position of the
first lower electrode 84, the larger the electric field between the
capillary 73 and the first lower electrode 84.
[0070] Porosity of the continuous film can be increased by reducing
the material flow rate, reducing the electrical field strength,
increasing the velocity of the first lower electrode 84, or
reducing the film thickness. The pattern of motion of the support
64 may be controlled to fabricate a mesh- or web-like film layer. A
skilled artisan will be able to readily determine the necessary
combination of parameters for the given material.
[0071] In one embodiment, the outer layer of the wound dressing 22
is the first layer deposited on the support 64, which minimizes
potential contamination transfer from the support to the internal
wound dressing layer that will contact the wound 20. In another
embodiment of the invention, the inner layer of the wound dressing
22, which will contact the wound 20 is the first layer deposited on
the support 64, which minimizes potential contamination transfer
from the ambient environment to the internal wound dressing
layer.
[0072] The wound dressing fabrication may be done on a support and
packaged for storage before use. The package is sterile and
hermetic. The package may be vacuumed or filled with a gas to
provide dry or inert or non-oxidizing ambient inside the package.
In one embodiment, the support for the wound dressing application
is at least partially a part of the wound dressing package. The
manufactured dressing may be additionally placed in a water vapor,
water, contamination impermeable bag with moisture absorbent.
[0073] The system may be provided with a sub-system for packing the
fabricated dressing in a sterile and hermetic package. Any known or
to be invented means and mechanisms for packaging may be used like
bagging, wrapping in a film with the following thermo-compress
sealing, etc. The auxiliary support may be at least a part of the
package and made of the packaging material. The packaging material
may be supplied in form of roll or stack of a film, or may be
fabricated by spraying or extrusion in the system by any known or
to be invented method and apparatus.
[0074] Another embodiment of the present invention is an apparatus
90 for wound dressing fabrication (see FIGS. 8 and 9). The
apparatus 90 includes a housing 92, deposition tools 94, in
deposition table 96, and a controller 98. The housing 92 may be a
hermetic enclosure that provides a protected environment for the
dressing fabrication. In FIGS. 8 and 9, the housing 92 is shown
without front panels for better visibility of the components. The
ambient pressure inside the enclosure may be kept positive
relatively the atmospheric pressure to prevent penetration of the
potentially contaminated air from outside. The enclosure interior
may be provided with short wave ultra-violet lamps (not shown) for
in-situ sterilization of the internal volume and dressing
components.
[0075] The deposition table 96 includes a two (x,y) or three
(x,y,z) dimensional motorized stage 102. The deposition table 96 is
installed inside the housing 92. The deposition table 96 may be
made of conductive material and provided with means for temperature
stabilization. The deposition tools 94 include a melt film extruder
104, a microfiber with electro-spinner 106, and an applicator 108.
The melt film extruder 104 and the electro-spinner 106 are used to
fabricate the main dressing components. For example, they can be
used to fabricate the backing film and the hydrophilic micro-fiber
layer.
[0076] Cartridges 110 may hold the polymers and/or therapeutic
adjuvants, that are necessary for the wound dressing fabrication
(including any of the materials identified above). The cartridges
110 include displacement pumps for controlled delivery of the
materials to the deposition tools 94. The controller 98 controls
these displacement pumps along with the motion of the deposition
table 96.
[0077] The melt film extruder 104 is used for fabrication of the
backing film of the wound dressing. It includes a barrel 112,
filled with the polymer and heated to the temperature recommended
for extrusion of that polymer. For example, polyurethane
PELLETHANE, available from Dow Chemical, Inc. is extruded at a
recommended temperature of from 190.degree. C. to 210.degree. C.
The barrel 112 has an outlet slot or orifice at its bottom for the
polymer extrusion under pressure created by the actuator 114.
During film extrusion, the outlet orifice faces the table 96 and
leaves the thin film on its surface in accordance with the pattern
programmed for the motorized stage 102.
[0078] The electro-spinner 106 is used for fabrication of the
dressing microfiber layer using a fiber electro-spinning technique,
such as is described in application Ser. No. 10/382,422, entitled,
"Method and Apparatus for Forming a Microfiber Coating," which has
been incorporated by reference herein. In one embodiment, the
microfibers are deposited onto the table 96 surface within an area
having a diameter of about 20 mm. Programmed motion of the
motorized stage 102 is used to cover larger or irregular shape
areas of the dressing.
[0079] The applicator 108 may be used for application of hydrogel
or therapeutic adjuvants or medical adhesive according to the
dressing design requirements by dispensing the substances through
the capillaries 116. The substance flow rate is provided by the
corresponding displacement pumps 110.
EXAMPLE
[0080] The device 56 has been used for fabrication of a two layer
wound dressing having a rectangular outer layer with a size of
about 100 by 80 mm and a round internal layer having a diameter of
about 50 mm. The electro-hydrodynamic method of microfiber
deposition, described above, has been used for both the inner layer
and outer layer with changes of material flow rate and
electrostatic field value.
[0081] A mixture of polyvinilpirralidone (M=360,000) and
poly-d,l-lactide (M=150,000), in ratio 1:10, and 80% of solvent
ethyl acetate has been used. Flow rate of the mixture was 1 mL/min
for the inner dressing layer and 2.5 mL/min for the outer dressing
layer. Electrical field strength between the capillary and grounded
support was 1.5 kV/cm for the inner dressing layer and 0.5 kV/cm
for the outer dressing layer. The distance between the cartridge
outlet and the surface was 10 cm. The velocity of the support
relative the capillary was 0.5 cm/sec and scanning overlapping was
70%. The internal dressing layer was fabricated as a micro-fiber
layer with thickness 1 mm and with size of the micro-fibers about
0.2 micron. The outer dressing layer was fabricated as a continuous
film with a thickness of 20-microns and porosity less than 0.5
micron. The internal layer provides wound exudate absorbing
properties and transport of the exudate to the external layer. The
external layer allowed evaporation of the water from the internal
layer to keep balanced moist environment over the wound. Due to its
porosity, the outer layer allowed air supply to the wound and, at
the same time, prevented contamination and infection of the wound
by protecting it from the dust and aerosols that may carry
bacteria.
[0082] As can be seen from the foregoing, a method of treating a
wound using a customized dressing has been provided in one
embodiment of the invention. In the method, at least one wound
characteristic is evaluated. A treatment need as a function of the
at least one wound characteristic is determined. A dressing having
a dressing characteristic responsive to the treatment need is
fabricated and applied to the wound.
[0083] In another embodiment of the method, a method of fabricating
a dressing to treat a patient having a wound with at least first
and second contiguous regions is provided. The method includes the
step of evaluating the wound characteristics of the first region of
the wound. The size and shape of the first region of the wound is
determined and a dressing having a first portion with a size and
shape corresponding to the size and shape of the first region and
made from a first material for enhancing treatment of the wound
characteristics of the first region of the wound is fabricated.
[0084] In another embodiment of the invention, a wound dressing for
treating a patient having a wound with at least first and second
contiguous regions surrounded by skin is provided. The dressing
includes a laminate structure having a first portion made from a
first material adapted for engaging the first region of the wound
and a second portion made from a second material different than the
first material adapted for engaging the second region of the wound.
The laminate structure includes an adhesive layer for adhering the
laminate structure to the skin of the patient.
[0085] In a further embodiment of the invention, a system for
fabricating a wound dressing for treatment of a wound is provided.
The system includes assessment means for assessing a plurality of
wound characteristics associated with the wound, a processor for
determining a set of parameters of the wound dressing, based on the
plurality of wound characteristics, and fabrication means for
fabricating the wound dressing based on the set of parameters.
[0086] In another embodiment of the invention, an apparatus is
provided for fabricating a wound dressing. The apparatus includes a
stage having a fabrication surface, a deposition source of a
material directed toward the stage, and at least one controller for
controlling a relative position between the deposition source and
the stage based on a set of characteristics of the wound. The
controller is coupled to the source for activating the source based
on the set of wound characteristics and the relative position
between the source and the stage.
[0087] Although the present invention has been described with
reference to exemplary embodiments, persons skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention. In
particular, the coatings produced according to the present
invention are not necessarily limited to those achieved using the
apparatus described. Thus, the scope of the invention shall include
all modifications and variations that may fall within the scope of
the claims.
* * * * *