U.S. patent application number 13/488616 was filed with the patent office on 2013-06-06 for portable negative pressure wound therapy device.
This patent application is currently assigned to TYCO HEALTHCARE GROUP LP. The applicant listed for this patent is James Augustine, William Durkin, Steven Kleis, Scott Wudyka. Invention is credited to James Augustine, William Durkin, Steven Kleis, Scott Wudyka.
Application Number | 20130144235 13/488616 |
Document ID | / |
Family ID | 41505826 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130144235 |
Kind Code |
A1 |
Augustine; James ; et
al. |
June 6, 2013 |
Portable Negative Pressure Wound Therapy Device
Abstract
A portable NPWT system includes a dressing assembly for
positioning over a wound to apply a negative pressure to the wound
and a canister assembly. The canister assembly includes a control
unit having a vacuum source and a controller and a collection
canister in communication with the dressing assembly operable to
receive fluid from the wound. The collection canister has ports to
introduce a vacuum from the vacuum source into the collection
canister. A ball float is provided to substantially close the
suction port in response to one of collection of a predetermined
volume of exudate in the collection canister, tilting of the
collection canister beyond a predetermined angle of orientation or
inversion of the collection canister.
Inventors: |
Augustine; James;
(Bridgewater, MA) ; Wudyka; Scott; (Marlborough,
MA) ; Durkin; William; (Appleton, WI) ; Kleis;
Steven; (Sherwood, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Augustine; James
Wudyka; Scott
Durkin; William
Kleis; Steven |
Bridgewater
Marlborough
Appleton
Sherwood |
MA
MA
WI
WI |
US
US
US
US |
|
|
Assignee: |
TYCO HEALTHCARE GROUP LP
Mansfield
MA
|
Family ID: |
41505826 |
Appl. No.: |
13/488616 |
Filed: |
June 5, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12486379 |
Jun 17, 2009 |
8257328 |
|
|
13488616 |
|
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|
61078838 |
Jul 8, 2008 |
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Current U.S.
Class: |
604/320 |
Current CPC
Class: |
A61M 2205/3382 20130101;
A61M 2205/3331 20130101; A61M 1/0031 20130101; A61M 27/00 20130101;
A61M 2209/088 20130101; A61M 2205/21 20130101; A61M 1/005 20140204;
A61M 1/0049 20130101; A61M 1/0088 20130101 |
Class at
Publication: |
604/320 |
International
Class: |
A61M 1/00 20060101
A61M001/00 |
Claims
1. A portable negative pressure wound therapy system comprising: a
dressing assembly for positioning over a wound to apply a negative
pressure to the wound; and a canister assembly dimensioned to be
worn by a user, said canister assembly including: a control unit
having a negative pressure source and a controller; and a
collection canister in communication with the dressing assembly and
having a chamber operable to receive fluid from the wound, the
collection canister including: a suction port in fluid
communication with said negative pressure source; and a ball float
arrangement having a ball float operable to substantially close
said suction port in response to one of collection of a
predetermined volume of exudate in the collection canister, tilting
of the collection canister beyond a predetermined angle of
orientation or inversion of the collection canister.
2. The portable negative pressure wound therapy system according to
claim 1, wherein said control unit further comprises a pressure
transducer operable to measure a pressure level in said collection
canister.
3. The portable negative pressure wound therapy system according to
claim 2, wherein said pressure transducer provides a signal to said
controller based on the measured pressure level and said controller
controls said negative pressure source based on the signal.
4. The portable negative pressure wound therapy system according to
claim 2, wherein said control unit further comprises a first
transducer port coupled to said pressure transducer, said first
transducer port has a protrusion coupled thereto; and said
collection canister has a second transducer port, said second
transducer port having a valve to prevent exudate from exiting said
collection canister, said protrusion opens said valve when said
control unit is attached to said collection canister so that said
pressure transducer can measure the pressure level in said
collection canister.
5. The portable negative pressure wound therapy system according to
claim 1 further comprising a pressure transducer operable to
measure a pressure level at an inlet of said negative pressure
source, said pressure transducer measures an increase in the
pressure level when said ball float closes said suction port and
said controller turns off or reduces an output of said negative
pressure source based on the measured increase in the pressure
level.
6. The portable negative pressure wound therapy system according to
claim 5, wherein said pressure transducer is a pressure switch.
7. The portable negative pressure wound therapy system according to
claim 1, wherein said ball float assembly having said ball float
includes a ball seat housing coupled to said suction port, said
ball seat housing having a ball seat in fluid communication with
said suction port, said ball float rests in said ball seat when
said predetermined volume of exudate in the collection canister is
collected.
8. The portable negative pressure wound therapy system according to
claim 6 further comprising a ball cage coupled to said ball seat
housing, said ball float being housed in said ball cage.
9. The portable negative pressure wound therapy system according to
claim 1, wherein said ball float has a coating, said coating
includes a hydrophobic material, latex, or polytetrafluoroethylene
(PTFE).
10. The portable negative pressure wound therapy system according
to claim 1, wherein said ball float has at least one grove.
11. The portable negative pressure wound therapy system according
to claim 1, wherein said control unit is reusable.
12. The portable negative pressure wound therapy system according
to claim 1, wherein said collection canister is disposable.
13. A portable negative pressure wound therapy system comprising: a
dressing assembly for positioning over a wound to apply a negative
pressure to the wound; and a canister assembly including: a control
unit having a negative pressure source and a controller; and a
collection canister in communication with the dressing assembly and
having a chamber operable to receive fluid from the wound, the
collection canister including: a suction port in fluid
communication with said negative pressure source; and a closure
valve mounted adjacent the suction port, the closure valve adapted
to move from an open position where the negative pressure source is
capable of drawing a vacuum in the collection canister through the
suction port and a closed position where the suction port is
substantially closed in response to one of collection of a
predetermined volume of exudate in the collection canister, tilting
of the collection canister beyond a predetermined angle of
orientation or inversion of the collection canister.
14. The portable system according to claim 13 wherein the closure
valve is mounted for pivotal movement to thereby pivot between the
open and closed positions thereof.
15. The portable system according to claim 14 including means for
biasing the closure valve toward the open position.
16. The portable system according to claim 14 including a filter
disposed adjacent the vacuum port, the closure valve being adapted
to at least partially cover the filter when in the closed position
of the closure valve.
17. The portable system according to claim 14 wherein the filter is
a hydrophobic filter.
Description
CROSS-REFERENCE TO RELATED DOCUMENTS
[0001] The present invention claims the benefit of and priority to
U.S. provisional patent Application Ser. No. 61/078,838, filed on
Jul. 8, 2008, disclosure of which may be referred to herein by
reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates generally to treating a wound
by applying negative pressure to the wound, and, more specifically,
to a portable negative pressure wound therapy system for treating a
wound.
[0004] 2. Description of Related Art
[0005] Wound closure involves the migration of epithelial and
subcutaneous tissue adjacent the wound towards the center and away
from the base of the wound until the wound closes. Unfortunately,
closure is difficult with large wounds, chronic wounds or wounds
that have become infected. In such wounds, a zone of stasis (i.e.
an area in which localized swelling of tissue restricts the flow of
blood to the tissues) forms near the surface of the wound. Without
sufficient blood flow, the epithelial and subcutaneous tissues
surrounding the wound not only receive diminished oxygen and
nutrients, but, are also less able to successfully fight microbial
infection and, thus, are less able to close the wound naturally.
Such wounds have presented difficulties to medical personnel for
many years.
[0006] Negative pressure wound therapy (NPWT), also known as
suction or vacuum therapy, has been used in treating and healing
wounds. Application of negative pressure, e.g. reduced or
sub-atmospheric pressure, to a localized reservoir over a wound has
been found to assist in closing the wound by promoting blood flow
to the area, stimulating the formation of granulation tissue, and
encouraging the migration of healthy tissue over the wound.
Negative pressure may also inhibit bacterial growth by drawing
fluids from the wound such as exudates, which may tend to harbor
bacteria. This technique has proven particularly effective for
chronic or healing-resistant wounds, and is also used for other
purposes such as post-operative wound care.
[0007] Generally, negative pressure therapy provides for a wound
covering to be positioned over the wound to facilitate suction at
the wound area. A conduit is introduced through the wound covering
to provide fluid communication to an external vacuum source.
Atmospheric gas, wound exudates, or other fluids may thus be drawn
from the reservoir through the fluid conduit to stimulate healing
of the wound. Exudates drawn from the reservoir may be deposited in
a collection canister.
[0008] Often, a portable NPWT device is worn by the patient so that
the patient may remain ambulatory instead of being confined to a
stationary position. While a patient is ambulatory, the portable
NPWT device tends to tip or tilt in a multitude of directions. If
there are enough exudates in the collection canister, the exudates
may cover a suction port leading from the vacuum source to the
collection canister because fluid
[0009] In addition, portable NPWT devices have a control unit
attached to the canister. The control unit generally contains the
suction pump and sensitive electronics such as a pressure
transducers, microprocessors, or the like. When the NPWT device
tips, exudate may aspirate from the canister into the control unit
thereby damaging the suction pump and/or electronic components.
SUMMARY
[0010] The present disclosure relates to a portable NPWT system
including a dressing assembly for positioning over a wound to apply
a negative pressure to the wound and a canister assembly. The
canister assembly includes a control unit having a vacuum source
and a controller and a collection canister in communication with
the dressing assembly operable to receive fluid from the wound. The
collection canister has ports to introduce a vacuum from the vacuum
source into the collection canister. A ball float is provided to
substantially close the suction port in response to one of
collection of a predetermined volume of exudate in the collection
canister, tilting of the collection canister beyond a predetermined
angle of orientation or inversion of the collection canister.
[0011] The present disclosure also relates to a portable NPWT
system including a dressing assembly for positioning over a wound
to apply a negative pressure to the wound and a canister assembly.
The canister assembly includes a control unit having a vacuum
source and a controller and a collection canister in communication
with the dressing assembly operable to receive fluid from the
wound. The collection canister has ports to introduce a vacuum from
the vacuum source into the collection canister. A closure valve
mounted adjacent to the suction port is provided and is adapted to
move from an open position where the negative pressure source is
capable of drawing a vacuum in the collection canister through the
suction port and a closed position where the suction port is
substantially closed in response to one of collection of a
predetermined volume of exudate in the collection canister, tilting
of the collection canister beyond a predetermined angle of
orientation or inversion of the collection canister.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Various embodiments of the wound dressing system of the
present disclosure are described herein with reference to the
drawings wherein:
[0013] FIG. 1 is a diagram of an embodiment of a NPWT system in
accordance with the present disclosure;
[0014] FIG. 2 is a diagram of an embodiment of a NPWT system in
accordance with the present disclosure;
[0015] FIG. 3 is a system diagram of a control system for a NPWT
system in accordance with the present disclosure;
[0016] FIG. 4A is a diagram of a canister assembly for a NPWT
system in accordance with the present disclosure;
[0017] FIG. 4B is a diagram of a canister assembly for a NPWT
system in accordance with the present disclosure;
[0018] FIG. 5 is a diagram of a control unit for a NPWT system in
accordance with the present disclosure;
[0019] FIG. 6 is a diagram of a collection canister for a NPWT
system in accordance with the present disclosure;
[0020] FIG. 7A is a diagram of a collection canister for a NPWT
system in accordance with the present disclosure;
[0021] FIGS. 7B-7F are a diagrams of a ball floats for a NPWT
system in accordance with the present disclosure
[0022] FIG. 8 is a diagram of a canister assembly for a NPWT system
in accordance with the present disclosure;
[0023] FIG. 8 is a top view of a collection canister for a NPWT
system in accordance with the present disclosure;
[0024] FIG. 10 is a diagram of a canister assembly for a NPWT
system in accordance with the present disclosure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Various embodiments of the present disclosure provide NPWT
systems (or apparatus) including a collection canister having a
chamber to collect wound fluids. Embodiments of the presently
disclosed NPWT systems are generally suitable for use in applying
negative pressure to a wound to facilitate healing of the wound in
accordance with various treatment modalities. Embodiments of the
presently disclosed NPWT systems are entirely portable and may be
worn or carried by the user such that the user may be completely
ambulatory during the therapy period. Embodiments of the presently
disclosed NPWT apparatus and components thereof may be entirely
reusable or may be entirely disposable after a predetermined period
of use or may be individually disposable whereby some of the
components are reused for a subsequent therapy application.
[0026] Hereinafter, embodiments of the presently disclosed NPWT
systems and embodiments of the presently disclosed sensors for use
in NPWT systems will be described with reference to the
accompanying drawings. Like reference numerals may refer to similar
or identical elements throughout the description of the figures. As
used herein, "wound exudate", or, simply, "exudate", generally
refers to any fluid output from a wound, e.g., blood, serum, and/or
pus, etc. As used herein, "fluid" generally refers to a liquid, a
gas or both.
[0027] Referring to FIG. 1, a NPWT apparatus according to an
embodiment of the present disclosure is depicted generally as 10
for use on a wound bed "w" surrounded by healthy skin "s". NPWT
apparatus 10 includes a wound dressing 12 positioned relative to
the wound bed "w" to define a vacuum chamber 14 about the wound bed
"w" to maintain negative pressure at the wound area. Wound dressing
12 includes a contact layer 18, a wound filler 20 and a wound cover
24.
[0028] Contact layer 18 is intended for placement within the wound
bed "w" and may be relatively non-supportive or flexible to
substantially conform to the topography of the wound bed "w". A
variety of materials may be used for the contact layer 18. Contact
layer 18 selection may depend on various factors such as the
patient's condition, the condition of the periwound skin, the
amount of exudate and/or the condition of the wound bed "w".
Contact layer 18 may be formed from perforated film material. The
porous characteristic of the contact layer 18 permits exudate to
pass from the wound bed "w" through the contact layer 18. Passage
of wound exudate through the contact layer 18 may be substantially
unidirectional such that exudate does not tend to flow back into
the wound bed "w". Unidirectional flow may be encouraged by
directional apertures, e.g., apertures positioned at peaks of
undulations or cone-shaped formations protruding from the contact
layer 18. Unidirectional flow may also be encouraged by laminating
the contact layer 18 with materials having absorption properties
differing from those of the contact layer 18, or by selection of
materials that promote directional flow. A non-adherent material
may be selected for forming the contact layer 18 such that the
contact layer 18 does not tend to cling to the wound bed "w" or
surrounding tissue when it is removed. One example of a material
that may be suitable for use as a contact layer 18 is commercially
available under the trademark XEROFLOW.RTM. offered by Tyco
Healthcare Group LP (d/b/a Covidien). Another example of a material
that may be suitable for use as the contact layer 18 is the
commercially available CURITY.RTM. non-adherent dressing offered by
Tyco Healthcare Group LP (d/b/a Covidien).
[0029] Wound filler 20 is positioned in the wound bed "w" over the
contact layer 18 and is intended to transfer wound exudate. Wound
filler 20 is conformable to assume the shape of any wound bed "w"
and may be packed up to any level, e.g., up to the level of healthy
skin "s" or to overfill the wound such that wound filler 20
protrudes over healthy skin "s". Wound filler 20 may be treated
with agents such as polyhexamethylene biguanide (PHMB) to decrease
the incidence of infection and/or other medicaments to promote
wound healing. A variety of materials may be used for the wound
filler 20. An example of a material that may be suitable for use as
the wound filler 20 is the antimicrobial dressing commercially
available under the trademark KERLIX.TM. AMD offered by Tyco
Healthcare Group LP (d/b/a Covidien).
[0030] Cover layer 24 may be formed of a flexible membrane, e.g., a
polymeric or elastomeric film, which may include a biocompatible
adhesive on at least a portion of the cover layer 24, e.g., at the
periphery 26 of the cover layer 24. Alternately, the cover layer 24
may be a substantially rigid member. Cover layer 24 may be
positioned over the wound bed "w" such that a substantially
continuous band of a biocompatible adhesive at the periphery 26 of
the cover layer 24 forms a substantially fluid-tight seal with the
surrounding skin "s". An example of a material that may be suitable
for use as the cover layer 24 is commercially available under the
trademark CURAFORM ISLAND.RTM. offered by Tyco Healthcare Group LP
(d/b/a Covidien).
[0031] Cover layer 24 may act as both a microbial barrier and a
fluid barrier to prevent contaminants from entering the wound bed
"w" and to help maintain the integrity thereof.
[0032] In one embodiment, the cover layer 24 is formed from a
moisture vapor permeable membrane, e.g., to promote the exchange of
oxygen and moisture between the wound bed "w" and the atmosphere.
An example of a membrane that may provide a suitable moisture vapor
transmission rate (MVTR) is a transparent membrane commercially
available under the trade name POLYSKIN.RTM. II offered by Tyco
Healthcare Group LP (d/b/a Covidien). A transparent membrane may
help to permit a visual assessment of wound conditions to be made
without requiring removal of the cover layer 24.
[0033] Wound dressing 12 may include a vacuum port 30 having a
flange 34 to facilitate connection of the vacuum chamber 14 to a
vacuum system. Vacuum port 30 may be configured as a rigid or
flexible, low-profile component and may be adapted to receive a
conduit 36 in a releasable and fluid-tight manner. An adhesive on
at least a portion of the underside of the flange 34 may be used to
provide a mechanism for affixing the vacuum port 30 to the cover
layer 24. The relative positions, size and/or shape of the vacuum
port 30 and the flange 34 may be varied from an embodiment depicted
in FIG. 1. For example, the flange 34 may be positioned within the
vacuum chamber 14 such that an adhesive on at least a portion of an
upper side surface of the flange 34 affixes the vacuum port 30 to
the cover layer 24. A hollow interior portion of the vacuum port 30
provides fluid communication between the conduit 36 and the vacuum
chamber 14. Conduit 36 extends from the vacuum port 30 to provide
fluid communication between the vacuum chamber 14 and the vacuum
source 40. Alternately, the vacuum port 30 may not be included in
the dressing 12 if other provisions are made for providing fluid
communication with the conduit 36.
[0034] Any suitable conduit may be used for the conduit 36,
including conduit fabricated from flexible elastomeric or polymeric
materials. In the NPWT apparatus 10 illustrated in FIG. 1, the
conduit 36 includes a first conduit section 36A, a second conduit
section 36B, a third conduit section 36C and a fourth conduit
section 36D. The first conduit section 36A extends from the vacuum
port 30 and is coupled via a fluid line coupling 100 to the second
conduit section 36B, which extends to the collection canister 38.
The third conduit section 36C extends from the collection canister
38 and is coupled via another fluid line coupling 100 to the fourth
conduit section 36D, which extends to the vacuum source 40. The
shape, size and/or number of conduit sections of the conduit 36 may
be varied from the first, second, third and fourth conduit sections
36A, 36B, 36C and 36D depicted in FIG. 1.
[0035] The first, second, third and fourth conduit sections 36A,
36B, 36C and 36D of the conduit 36 may be connected to components
of the apparatus 10 by conventional air-tight means, such as, for
example, friction fit, bayonet coupling, or barbed connectors. The
connections may be made permanent. Alternately, a quick-disconnect
or other releasable connection means may be used to provide some
adjustment flexibility to the apparatus 10.
[0036] Collection canister 38 may be formed of any type of
container that is suitable for containing wound fluids. For
example, a semi-rigid plastic bottle may be used for the collection
canister 38. A flexible polymeric pouch or other hollow container
body may be used for the collection canister 38. Collection
canister 38 may contain an absorbent material to consolidate or
contain the wound fluids or debris. For example,
[0037] The collection canister 38 is in fluid communication with
the wound dressing 12 via the first and second conduit sections
36A, 36B. The third and fourth conduit sections 36C, 36D connect
the collection canister 38 to the vacuum source 40 that generates
or otherwise provides a negative pressure to the collection
canister 38. Vacuum source 40 may include a peristaltic pump, a
diaphragmatic pump, continuous pump or other suitable mechanism.
Vacuum source 40 may be a miniature pump or micropump that may be
biocompatible and adapted to maintain or draw adequate and
therapeutic vacuum levels. The vacuum level of subatmospheric
pressure achieved may be in the range of about 20 mmHg to about 500
mmHg. In embodiments, the vacuum level may be about 75 mmHg to
about 125 mmHg, or about 40 mmHg to about 80 mmHg. One example of a
peristaltic pump that may be used as the vacuum source 40 is the
commercially available Kangaroo PET Eternal Feeding Pump offered by
Tyco Healthcare Group LP (d/b/a Covidien). Vacuum source 40 may be
actuated by an actuator (not shown) which may be any means known by
those skilled in the art, including, for example, alternating
current (AC) motors, direct current (DC) motors,
[0038] In embodiments, the NPWT apparatus 10 includes one or more
fluid line couplings 100 that allow for selectable coupling and
decoupling of conduit sections. For example, a fluid line coupling
100 may be used to maintain fluid communication between the first
and second conduit sections 36A, 36B when engaged, and may
interrupt fluid flow between the first and second conduit sections
36A, 36B when disengaged. Thus, fluid line coupling 100 may
facilitate the connection, disconnection or maintenance of
components of the NPWT apparatus 10, including the replacement of
the collection canister 38. Additional or alternate placement of
one or more fluid line couplings 100 at any location in line with
the conduit 36 may facilitate other procedures. For example, the
placement of a fluid line coupling 100 between the third and fourth
conduit sections 36C, 36D, as depicted in FIG. 1, may facilitate
servicing of the vacuum source 40.
[0039] Referring to FIG. 2, the NPWT system shown generally as 200
can be worn by a patient or user and includes a dressing assembly
210, a wound port assembly 220, an extension assembly 230 and a
canister assembly 240. Dressing assembly 210 is positioned relative
to the wound area to define a vacuum chamber about the wound area
to maintain negative pressure at the wound area. Dressing assembly
210 may be substantially sealed from extraneous air leakage, e.g.,
using adhesive coverings. Wound port assembly 220 is mounted to the
dressing assembly 210. For example, wound port assembly 220 may
include a substantially continuous band of adhesive at its
periphery for affixing the wound port assembly 220 to the dressing
assembly 210. Extension assembly 230 is coupled between the wound
port assembly 220 and the canister assembly 240 and defines a fluid
flow path between the wound port assembly 220 and the canister
assembly 240. A hollow interior of the wound port assembly 220
provides fluid communication between the extension assembly 230 and
the interior of the dressing assembly 210. Dressing assembly 210
and the wound port assembly 220 shown in FIG. 2 are similar to
components of the wound dressing 12 of FIG. 1 and further
description thereof is omitted in the interests of brevity.
[0040] Canister assembly 240 includes a control unit 246 and a
collection canister 242 disposed below the control unit 246.
Control unit 246 may be reusable and collection canister 242 may be
disposable. Control unit 246 and the collection canister 242 may be
releasably coupled. Mechanisms for selective coupling and
decoupling of the control unit 246 and the collection canister 242
include fasteners, latches, clips, straps, bayonet mounts, magnetic
couplings, and other devices. Collection canister 242 may consist
of any container suitable for containing wound fluids.
[0041] In one embodiment, the NPWT system 200 is capable of
operating in a continuous mode or an alternating mode. In the
continuous mode, the control unit 246 controls a pump to
continuously supply a selected vacuum level at the collection
canister 242 to create a reduced pressure state within the dressing
assembly 210. In the alternating mode, the control unit 246
controls the pump to alternating supply a first negative pressure,
e.g., about 80 mmHg, at the collection canister 242 for a preset
fixed amount of time and a second negative pressure, e.g., about 50
mmHg, at the collection canister 242 for a different preset fixed
amount of time.
[0042] In general, the output of the pump is directly related to
the degree of air leakage in the NPWT system 200 and the open
volume in the collection canister 242. If there is sufficient air
leakage in the system 200, e.g., at the dressing assembly 210, the
pump can remain on continuously and the control unit 246 can
control negative pressure at the collection canister 242 by
adjusting the pump speed. Alternatively, if there is not sufficient
air leakage in the system 200 to permit the pump to remain on
continuously, the control unit 246 can control negative pressure at
the collection canister 242 by turning the pump on and off, e.g.,
for non-equal on/off periods of time.
[0043] Canister assembly 240 may be constructed from a variety of
materials such as Lucite.TM. polycarbonate, metals, metal alloys,
plastics, or other durable materials capable of withstanding forces
applied during normal use, and may have some capability of
withstanding possibly excessive forces resulting from misuse.
Collection canister 242 may include a window with fluid level
markings or for promoting visual assessment of the amount of
exudate contained within the collection canister 242. A transparent
or partially transparent collection canister 242 may thus assist in
determining the remaining capacity of the collection canister 242
and/or when the collection canister 242 should be replaced.
[0044] Referring to FIG. 3, the NPWT device has a control system
generally shown as 300. Control system 300 may include a controller
310 that controls the operation of the NPWT device. Controller 310
may include at least one processor 312 and at least one memory
module 314. The memory module 314 may be a volatile memory (e.g.
DRAM, SRAM, or the like) or a non-volatile memory (e.g., ROM, PROM,
EPROM, EEPROM, a semiconductor flash memory, or the like). The
memory module 314 stores instructions that are executed by the
processor 312 for controlling the NPWT device.
[0045] Controller 310 controls a vacuum source 320 based on the
mode of therapy selected as well as inputs received from pressure
transducer 330 and pressure transducer 330. Vacuum source 320 may
be a miniature pump or micropump that may be biocompatible and
adapted to maintain or draw adequate and therapeutic vacuum levels.
The vacuum level of subatmospheric pressure achieved may be in the
range of about 20 mmHg to about 500 mmHg. In embodiments, the
vacuum level may be about 75 mmHg and about 125 mmHg, or between
about 30 mmHg and 80 mmHg. Vacuum source 320 is actuated by an
actuator which may be any means known by those skilled in the art,
including, for example, AC motors, DC motors, voice coil actuators,
solenoids, etc.
[0046] Controller 310 maintains a selected vacuum level at the
canister 242 by monitoring the pressure in the canister 242 using
pressure transducer 330. If the vacuum level in the canister 242
exceeds a threshold as measured by pressure transducer 340, the
controller 310 turns the vacuum source 320 off or reduces the
output of the vacuum source 320 to reduce the vacuum level in the
canister 242. If the vacuum level in the canister 242 falls below a
threshold as measured by pressure transducer 340, the controller
310 turns the vacuum source 320 on or increases the output of the
vacuum source 320 to increase the vacuum level in the canister
242.
[0047] Controller 310 also controls operation of the vacuum source
320 based on the output of pressure transducer 340. Pressure
transducer 340, which could be a pressure switch, monitors the
pressure at the inlet of the vacuum source 320 to determine a
pressure spike indicative of the replace canister condition which
will be described in more detail below. Alternately, if a pressure
switch is used, once a threshold of negative pressure is reached,
it will actuate thereby signaling the controller 310 to turn the
vacuum source 320 off.
[0048] Control system 300 may include a speaker 350 to produce an
audible indication to notify the user of a condition, e.g., leak,
canister assembly tip, failed pressure sensor, failed pump,
excessive vacuum, or low battery conditions. The control system 300
may also include a display 360 to notify a user of an alarm
condition, a state of the NPWT device, or other information related
to the treatment of a wound by the NPWT device. Display 360 may be
a liquid crystal display (LCD), a light emitting diode (LED)
display, or any number of LEDs, neon lamps, incandescent bulbs, or
the like.
[0049] Control system 300 responds to various sensed events by
signaling alarms. Various types of conditions may be signaled by
alarms. In embodiments, control system 300 is capable of signaling
alarms for failed pressure sensor condition, use odometer expired
condition, watchdog reset condition, failed pump condition, leak
condition, replace canister condition, excessive vacuum condition,
failed LEDs condition, low battery condition, very low battery
condition, and failed battery condition. Priority levels may be
associated with alarms. In embodiments, the priority levels of
alarms are low priority alarm, medium priority alarm, and system
alarm (highest priority). Low priority alarms, when triggered, may
be continuously indicated. Medium priority alarms and system
alarms, when triggered, may have a flashing indication.
[0050] Control system 300 may stop operation of the in response to
an alarm, e.g., depending on alarm type and/or priority level. In
embodiments, the control system 300 stops operation of the pump in
response to system alarms, e.g., failed pressure sensor system
alarm, use odometer expired system alarm, watchdog reset system
alarm, failed pump system alarm, excessive vacuum system alarm,
and/or failed LEDs system alarm.
[0051] If an air leak develops in the NPWT system 200, e.g., at the
dressing assembly 210, for which the control unit 246 cannot
compensate by increasing the pump speed, the control system 300 may
indicate an alarm. For example, the control system 300 may indicate
a leak alarm after two consecutive minutes of operation in which
the vacuum level is below the current set point (or below the
minimum level of a set point range).
[0052] In embodiments, the control system 300 includes a user
interface (not shown) which may be incorporated into the display
360 or may be a set of user actuated switches or buttons. The user
turns ON the canister assembly 240 by pressing a power button (not
shown). When the power button is pressed, the control system 300
performs a series of internal checks during power up. In one
embodiment, after successfully completing the power-up tasks, the
control system 300 turns on the pump 320 using the stored settings.
At initial activation of the canister assembly 240, the stored
settings are the default settings. In one embodiment, the default
settings for controlling the pump 320 are 80 mmHg and continuous
mode. In one embodiment, the currently stored vacuum level setting
can be altered by the user, e.g., to 50 mmHg. In one embodiment,
the currently stored mode setting can be altered by the user, e.g.,
to an alternating mode.
[0053] Referring to FIGS. 4A and 4B, the two cross-sectional views
of a canister assembly 240 illustrate the electronic, electrical
and pneumatic components of a NPWT device in accordance with an
embodiment of the present disclosure. At the top portion of the
control unit 246, immediately below a user interface (not shown),
is a printed circuit board (PCB) 402. Pressure transducer 330 is
attached to the PCB 402. The controller 310 includes circuits that
power the pressure transducer 330 and receive its pressure signals
(i.e., electrical signals indicative of the negative pressure being
measured). The PCB 402 includes signal processing circuits that
condition the signals, including filtering to reject electrical
noise and provide a clean signal to the controller 310.
[0054] Pressure transducer 330 has a hydrophobic filter at area
404, which protects the pressure transducer 330 if exudate fluid
entered a pressure transducer tube (not shown). The pressure
transducer is attached to the hydrophobic filter at area 404 and
the opposite end of the pressure transducer tube attaches to a
transducer port 503 (shown in FIG. 5), at the bottom of the control
unit 246. The tube is fit by friction. The transducer port 503 at
the bottom of the control unit 246 pneumatically communicates with
the canister 242 through the canister transducer port 604 (shown in
FIG. 6), when the canister 242 is attached to the control unit 246.
The pressure transducer 330 directly monitors the vacuum level at
the canister transducer port 604.
[0055] A pressure transducer 340 (shown in FIG. 4B), which could be
a pressure switch, may also be attached to the PCB 402. The
pressure transducer 340 has its own set of signal conditioning
circuits in controller 310 as may be required. A pressure
transducer tube 340T is attached to the neck of the pressure
transducer 340. The other end of the pressure transducer tube 340T
is attached to the pump inlet tube 408 (shown in FIG. 4A). The
pressure transducer 340 monitors the pressure at the pump inlet 412
to determine a pressure spike indicative of the replace canister
condition which will be described below.
[0056] A direct current (DC) motor-driven pump 410 is contained
within the control unit 246. A vibration damping tape, e.g.,
visco-elastic damping tape, may be applied to the outer surface of
the pump 410 to reduce vibration and its associated noise. The pump
410 may be contained within its own sub-housing 414 which may be
hollow or formed entirely of open cell molded foam, e.g., used as a
silencer to provide sound mitigation by reducing the sound energy
of the expelled air during operation. As part of the sound
mitigation arrangement, a tube may be fitted to the pump
sub-housing 414.
[0057] A pump inlet tube 408 is attached on one end to the inlet
port 412 of the pump 410 on one end. The other end of the pump
inlet tube 408 attaches to the filter assembly 416. The filter
assembly 416 has an orifice 418. A suction chamber is located
directly below the filter assembly 416 that receives the canister
suction port 601 (shown in FIGS. 6 & 7) when the canister 242
is attached to the control unit. 246.
[0058] FIG. 5 is a view of the bottom portion of the control unit
246 and illustrates a control unit suction port 504 and a control
unit transducer port 503. Control unit suction port 504 is
connected internally to the pump 510. The control unit transducer
port 503 is connected internally to the pressure transducer 330.
Associated with the control unit transducer port 503 is a
protrusion 505 which interfaces with the canister transducer port
604, which pushes open a silicone valve 420 (shown in FIG. 4B).
[0059] FIG. 6 illustrates the canister top 600 which encloses the
open volume of the canister 242. In FIG. 6, the canister top 600 is
depicted in the assembled condition with respect to the canister
242. The canister top 600 includes a canister suction port 601 and
a canister transducer port 604. The canister suction port 601 and
the canister transducer port 604 include respective o-rings 602,
605 which are received within the respective control unit suction
port 504 and the control unit transducer port 503 of the control
unit (FIG. 5) in fluid tight relation when the control unit 246 is
mounted to the canister top 600. The canister top 600 further
includes a wound exudate port 607 extending into the open volume
portion 608 of the canister 242 in fluid communication with
extension assembly 230 to receive exudate from the wound.
[0060] FIG. 7A illustrates the bottom portion 700 of canister top
600. The bottom portion 700 contains a suction port 601 with an
o-ring 602 as discussed before. A silicone valve 703, also known as
a rolling sleeve valve, may be located at the bottom of the suction
port 601. Below the silicone valve 703, is a splash guard 704,
which restricts contact of fluid with the silicone valve 703 if the
canister 242 is tipped or shaken while not attached to the control
unit 246. A ball seat housing 705 is below the splash guard 704,
further protecting the silicone valve and also providing an
attachment point to the ball cage 707. Inside of the ball seat
housing 705 is a recess that receives the ball seat 708. An orifice
709 is centered in the ball seat 708 embedded in the ball seat
housing. To prevent encrustation of bottom portion 700 and all
associated parts by the drying exudate, a coating may be applied to
the components, which inhibit this encrustation by affecting the
formation and binding of proteins or may decrease wettability to
allow liquid to shed. In conjunction with the splash guard 704 a
second layer may be added to it on the exudate side facing the open
volume canister that is permeable and does not allow exudate to
encrust upon it. Encrustation of the membrane inhibits air flow
through it.
[0061] When the ball float 706 contacts the seat 708, air flow to
the pump 410 is blocked while the pump 410 continues to run,
thereby producing the pressure spike mentioned, which indicates the
replace canister condition. A fixed leak is incorporated either
into the pump 410 or to the pump inlet tube 408, which is meant to
relieve the negative pressure at the pump inlet and at the floating
ball seat 708, so that the floating ball 706 can fall out of the
sealing position.
[0062] FIGS. 7B through 7F depict examples of ball floats that may
be used in the NPWT device according to an embodiment of the
present disclosure. To prevent encrustation of the ball float by
the drying exudate, a coating 712 may be applied to the ball float
710 (as shown in FIG. 7B), which inhibit this encrustation by
affecting the formation and binding of proteins or may decrease
wettability to allow liquid to shed. Coating 712 may be made from a
hydrophobic material, latex or TEFLON.RTM., or the like.
[0063] FIG. 7C depicts a ball float 720 having a groove or track
722 running along the center of the ball float 720. Groove 722
could be a straight line or a wavy line. FIG. 7D depicts a ball
float 730 having multiple grooves or tracks 732. Grooves 732 may be
arranged in concentric circles around to the ball float 730. The
distance between each concentric circle may be constant or may
vary. FIG. 7E depicts a ball float 740 having a first groove or
track 742 and a second groove or track 744. Groove 742 and groove
744 intersect each other at two points on ball float 740. The angle
".alpha." between groove 742 and groove 744 can range from greater
than 0.degree. to less than 180.degree.. FIG. 7F depicts a ball
float 750 having multiple grooves 752. Grooves 752 may be spaced
evenly around the ball float or spaced at varying degrees. Grooves
752 intersect each other at an axis of the ball float 750 generally
shown as 754.
[0064] FIGS. 8 and 9 illustrate a canister assembly 800 in
accordance with an embodiment of the present disclosure. Canister
assembly 800 includes housing 810, control unit 812 disposed within
the housing 810 and collection canister 814. Housing 810 may be any
suitable rigid member adapted for donning by the subject. Control
unit 812 may incorporate vacuum source or pump 824, actuator or
motor 826 for activating the vacuum source 824 and power source
828. Vacuum source 824 generates or otherwise provides negative
pressure to the wound.
[0065] Power source 828 may be disposed within housing 810 or
separately mountable to the housing 810. A suitable power source
828 includes alkaline batteries, wet cell batteries, dry cell
batteries, nickel cadmium batteries, solar generated means, lithium
batteries, NiMH batteries (nickel metal hydride) each of which may
be of the disposable or rechargeable variety.
[0066] Housing 810 further includes vent portal 830 configured to
vent exhaust air from vacuum source 824 through exhaust port 832.
Vent portal 830 extends from housing 810 and may be directly
connected to vacuum source 824. It is also envisions that vent
portal 830 may exhaust air from within housing 810 rather than
directly from vacuum source 824. Exhaust port 832 may include
filter 834 extending across the exhaust port 832. Filter 834 may be
a bacterial filter to prevent emission of bacteria from housing
810.
[0067] Collection canister 814 collects exudates "e" removed from
the wound bed "w` during therapy through conduit, or tubing, 806.
Collection canister 814 is associated with housing 810 and may be
incorporated within the housing 810 or releasably connected to the
housing 810 by conventional means. Housing 810 and collection
canister 814 of canister assembly 800 may be releasably coupled.
Mechanisms for selective coupling and decoupling of housing 810 and
collection canister 814 include fasteners, latches, clips, straps,
bayonet mounts, magnetic couplings, and other devices.
[0068] Collection canister 814 may comprise any container suitable
for containing wound fluids and is substantially rigid defining an
internal chamber 836 in fluid communication with tubing 806.
Collection canister 814 may contain an absorbent material to
consolidate or contain the wound drainage or debris. In
embodiments, at least a portion of collection canister 814 may be
transparent to assist in evaluating the color, quality, or quantity
of wound exudates. A transparent canister may thus assist in
determining the remaining capacity of the canister or when the
canister should be replaced. In the alternative, collection
canister 814 may be relatively flexible.
[0069] Collection canister 814 includes fluid inlet 838 and suction
port 840. Fluid inlet 838 is configured to operably engage conduit
806. Fluid inlet 838 may be connectable with conduit 806 by
conventional air and fluid tight means, such as those described
above. In embodiments, fluid inlet 838 may contain a luer lock or
other connector within the purview of those skilled in the art to
secure the end of conduit 806 with the fluid inlet 838. It is
envisioned that fluid inlet 838 is configured to receive a cap in
order to prevent leakage of exudates and odor from internal chamber
836 of collection canister 814 when housing 810 is separated from
the canister 814.
[0070] Suction port 840 is in fluid communication with vacuum
source 824 and may be an opening defined in a wall of housing 810.
A filter 842, such as a hydrophobic membrane or baffling to prevent
exudates from being aspirated into pump 810 may be disposed
adjacent or within suction port 840. Filter 842 may also include
charcoal or other odor absorbing materials and may prevent the
passage of bacteria. Pump 824 creates a vacuum within internal
chamber 836 of collection canister 832 by drawing air through
suction port 840.
[0071] Collection canister 814 includes closure valve 844. Closure
valve 844 is pivotally mounted about hinge 846 which is connected
to internal chamber surface of collection canister 814. Closure
valve 844 assumes the open position depicted in FIG. 8 when
collection canister 814 is upright and not filled with exudates
"e". Specifically, the gravitational weight of closure valve 844
will ensure that the closure valve is pivoted to the open condition
in the presence of the aforedescribed conditions. As an
alternative, closure valve 844 also may be resiliently biased to
the open position depicted as in FIG. 8. Means for biasing closure
valve 844 are envisioned including a torsion spring 848 mounted
about hinge 846 and operatively engageable with the closure valve
844. In the alternative, a leaf spring 850 may be connected to an
interior surface of canister 814 and extend into engagement with
closure valve 844 to normally bias the closure valve 844 to the
open position. In embodiments, closure valve 844 is at a
predetermined angle ".DELTA." when in the fully open position.
Angle may range from about 10.degree. to about 70.degree. relative
to the longitudinal axis "k" of collection canister 814. Closure
valve 844 is of sufficient weight or mass to remain in the open
condition even in the presence of a vacuum draw generated during
operation of pump 824.
[0072] Closure valve 844 prevents exudates from clogging and/or
entering pump 824 or control unit 812 when collection canister 814
is in an inverted or a tilted position. For example, when
collection canister 844 is tilted beyond a predetermined
orientation, e.g., when on its side or inverted with suction port
840 facing in a general downward direction, closure valve 844 moves
under its own weight, the weight of exudates, and/or gravity to a
closed position. Moreover, when tilted or inverted, closure valve
844 defines a moment arm thereby causing the closure valve 844 to
pivot about hinge 846 from the open position to the closed position
(FIG. 10). The moment arm defined by closure valve 844 may be
altered by adjusting the length or weight of the closure valve
844.
[0073] In the closed position of FIG. 10, closure valve 844 seals
suction port 840 thereby sealing the exudates "e" within canister
814 and/or preventing clogging of filter 842. It is envisioned that
closure valve 844 may define seat 852 which resides within suction
port 844 in sealed engagement with the wall surfaces defining the
suction port 840. Seat 852 may include an elastomeric member to
facilitate formation of a seal between the two components. In the
closed position, a vacuum change (e.g., drop in vacuum) will alert
the subject of the disoriented canister. The vacuum change may be
identified or recognized by the user through increased noise or
churning of the vacuum source 824. In the alternative, a pressure
transducer 856 may be in communication with internal chamber 836 to
detect changes in pressure. Logic associated with transducer 856
and vacuum source 824 may reduce the speed of vacuum source 824 or
stop operation of the vacuum source 824.
[0074] While the disclosure has been illustrated and described, it
is not intended to be limited to the details shown, since various
modifications and substitutions can be made without departing in
any way from the spirit of the present disclosure. As such, further
modifications and equivalents of the invention herein disclosed can
occur to persons skilled in the art using no more than routine
experimentation, and all such modifications and equivalents are
believed to be within the spirit and scope of the disclosure as
defined by the following claims.
* * * * *