U.S. patent application number 17/695598 was filed with the patent office on 2022-06-30 for system for purging negative pressure wound therapy system.
The applicant listed for this patent is KCI Licensing, Inc.. Invention is credited to Kevin W. BENDELE, Richard Daniel John COULTHARD, Christopher Brian LOCKE, James A. LUCKEMEYER.
Application Number | 20220203011 17/695598 |
Document ID | / |
Family ID | |
Filed Date | 2022-06-30 |
United States Patent
Application |
20220203011 |
Kind Code |
A1 |
COULTHARD; Richard Daniel John ;
et al. |
June 30, 2022 |
SYSTEM FOR PURGING NEGATIVE PRESSURE WOUND THERAPY SYSTEM
Abstract
Systems and methods for purging a negative pressure wound
therapy system
Inventors: |
COULTHARD; Richard Daniel John;
(Verwood, GB) ; BENDELE; Kevin W.; (Oldsmar,
FL) ; LUCKEMEYER; James A.; (San Antonio, TX)
; LOCKE; Christopher Brian; (Bournemouth, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KCI Licensing, Inc. |
San Antonio |
TX |
US |
|
|
Appl. No.: |
17/695598 |
Filed: |
March 15, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15874126 |
Jan 18, 2018 |
11305046 |
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17695598 |
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13452014 |
Apr 20, 2012 |
9907888 |
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15874126 |
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61477472 |
Apr 20, 2011 |
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International
Class: |
A61M 1/00 20060101
A61M001/00 |
Claims
1. A computer-readable medium comprising executable code for
controlling a negative-pressure wound therapy system, wherein the
executable code comprises: manipulating a position of a diverter
valve between a first position and a second position; wherein: the
diverter valve is coupled between an outlet of a negative-pressure
source and a dressing, the diverter valve is configured to allow
fluid flow from the outlet of the negative-pressure source to
atmosphere when the diverter valve is in the first position, and
the diverter valve is configured to prevent fluid flow from the
outlet of the negative-pressure source to the dressing when the
diverter valve is in the first position.
2. The computer-readable medium of claim 1, wherein: the diverter
valve is configured to allow fluid flow from the outlet of the
negative-pressure source to the dressing when the diverter valve is
in the second position.
3. The computer-readable medium of claim 1, wherein: the diverter
valve is configured to prevent fluid flow from the outlet of the
negative-pressure source to atmosphere when the diverter valve is
in the second position.
4. The computer-readable medium of claim 1, wherein the executable
code comprises: cycling the position of the diverter valve between
the first position and the second position.
5. The computer-readable medium of claim 1, wherein the executable
code comprises: manipulating the position of the diverter valve to
hold the position of the diverter valve in an intermediate
position; wherein the diverter valve is configured to allow a low
flow of fluid between the outlet of the negative-pressure source
and the dressing when the diverter valve is in the intermediate
position.
6. The computer-readable medium of claim 1, wherein: the
negative-pressure source further comprises an inlet; the inlet of
the negative-pressure source is configured for fluid communication
with the dressing via a first conduit; and the outlet of the
negative-pressure source is configured for fluid communication with
the dressing via a second conduit.
7. The computer-readable medium of claim 6, wherein: a first
pressure sensor is fluidly coupled to the first conduit.
8. The computer-readable medium of claim 6, wherein: a second
pressure sensor is fluidly coupled to the second conduit.
9. The computer-readable medium of claim 7, wherein the executable
code comprises: manipulating the position of the diverter valve
from the first position to the second position when a pressure at
the first pressure sensor reaches a predetermined value.
10. The computer-readable medium of claim 8, wherein the executable
code comprises: manipulating the position of the diverter valve
from the first position to the second position when a pressure at
the second pressure sensor reaches a predetermined value.
11. A method of controlling a negative-pressure wound therapy
system with a computer, comprising: manipulating, at a computer, a
position of a diverter valve between a first position and a second
position; wherein: the diverter valve is coupled between an outlet
of a negative-pressure source and a dressing, the diverter valve is
configured to allow fluid flow from the outlet of the
negative-pressure source to atmosphere when the diverter valve is
in the first position, and the diverter valve is configured to
prevent fluid flow from the outlet of the negative-pressure source
to the dressing when the diverter valve is in the first
position.
12. The method of claim 11, wherein: the diverter valve is
configured to allow fluid flow from the outlet of the
negative-pressure source to the dressing when the diverter valve is
in the second position.
13. The method of claim 11, wherein: the diverter valve is
configured to prevent fluid flow from the outlet of the
negative-pressure source to atmosphere when the diverter valve is
in the second position.
14. The method of claim 11, further comprising: cycling, at the
computer, the position of the diverter valve between the first
position and the second position.
15. The method of claim 11, further comprising: manipulating, at
the computer, the position of the diverter valve to hold the
position of the diverter valve in an intermediate position; wherein
the diverter valve is configured to allow a low flow of fluid
between the outlet of the negative-pressure source and the dressing
when the diverter valve is in the intermediate position.
16. The method of claim 11, wherein: the negative-pressure source
further comprises an inlet; the inlet of the negative-pressure
source is configured for fluid communication with the dressing via
a first conduit; and the outlet of the negative-pressure source is
configured for fluid communication with the dressing via a second
conduit.
17. The method of claim 16, wherein: a first pressure sensor is
fluidly coupled to the first conduit.
18. The method of claim 16, wherein: a second pressure sensor is
fluidly coupled to the second conduit.
19. The method of claim 17, further comprising: manipulating, at
the computer, the position of the diverter valve from the first
position to the second position when a pressure at the first
pressure sensor reaches a predetermined value.
20. The method of claim 18, further comprising: manipulating, at
the computer, the position of the diverter valve from the first
position to the second position when a pressure at the second
pressure sensor reaches a predetermined value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/874,126, filed Jan. 18, 2018, which is a
continuation of U.S. Patent Application Ser. No. 13/452,014, filed
Apr. 20, 2012, which claims priority to U.S. Provisional Patent
Application No. 61/477,472, filed Apr. 20, 2011, the entire
contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] This invention relates to a system and method for purging a
negative pressure wound therapy system.
Description of the Related Art
[0003] The referenced shortcomings are not intended to be
exhaustive, but rather are among many that tend to impair the
effectiveness of previously known techniques in purging a negative
pressure wound therapy (NPWT) system. However, those mentioned here
are sufficient to demonstrate that the methodologies appearing in
the art have not been satisfactory and that a significant need
exists for the techniques described and claimed in this
disclosure.
[0004] Advanced NPWT devices and systems use multiple fluid
channels to provide therapeutic negative pressure, transport wound
products (liquid and solid) and monitor the applied negative
pressure close to the wound site (via additional tubing lumens,
typically). During this process several problems can be
encountered, which can cause therapy to be interrupted or accuracy
to be compromised.
[0005] For example, the therapy line may be blocked by highly
viscous fluids, solid matter, or wound products coagulating in the
line due to long residency time when flow is restricted under low
leak conditions. In addition, the wound pressure sensing line may
be blocked by wound fluid and/or instillation fluid.
[0006] Current practice in some advanced NPWT products is to
periodically vent the wound pressure sensing line to atmosphere
(near the pump/sensor end of the line), which allows the vacuum in
the wound dressing to pull a short burst of air into the wound and
thus attempt to clear a blockage in the sensing lumen(s). However,
when instillation therapy is used in conjunction with NPWT, there
can be little or no vacuum at the wound site. Moreover, there is a
tendency for practitioners to over-fill the wound with instillation
fluid, which can drive instillation fluid up the wound pressure
sensing lines and thereby prevent accurate sensing of wound
pressure until the fluid in the wound pressure sensing lumen(s) is
removed. Wound pressure sensing is accurate only if there is a
clear air path between the sensor and wound site, and wound
pressure sensing will be degraded if there are slugs of fluid in
the sensing lines.
SUMMARY OF THE INVENTION
[0007] From the foregoing discussion, it should be apparent that a
need exists for effective systems and methods for purging an NPWT
system.
[0008] Systems and methods are presented for purging an NPWT
system. The method in the disclosed embodiments substantially
includes the steps necessary to carry out the functions presented
above with respect to the operation of the described system.
[0009] Certain embodiments comprise a system for purging a negative
pressure wound therapy system. In particular embodiments, the
system may comprise a negative pressure source comprising an inlet
and an outlet, where the inlet is configured for fluid
communication with a wound therapy dressing via a first conduit,
and the outlet is configured for fluid communication with a wound
therapy dressing via a second conduit. Particular embodiments may
also comprise a diverter valve coupled to the second conduit, where
the diverter valve is configured to allow a fluid flow from the
negative pressure source to atmosphere when the diverter valve is
in a first position and where the diverter valve is configured to
allow a fluid flow from the negative pressure source to a wound
therapy dressing through the second conduit when the diverter valve
is in a second position.
[0010] In particular embodiments, the diverter valve can be
configured to prevent fluid flow from the negative pressure source
to a wound therapy dressing through the second conduit when the
diverter valve is in the first position. In specific embodiments,
the diverter valve can be configured to prevent a fluid flow from
the negative pressure source to atmosphere when the diverter valve
is in the second position. Certain embodiments may further comprise
a pressure sensor configured to detect the pressure in the second
conduit. Particular embodiments may also comprise a reservoir in
fluid communication with the first and second conduits.
[0011] In specific embodiments, the diverter valve may be a
piezoelectric valve. In particular embodiments, the negative
pressure source can comprise a vacuum pump. Certain embodiments may
further comprise a pump configured to deliver instillation fluid to
a wound therapy dressing.
[0012] Particular embodiments may comprise a method of purging a
negative pressure wound therapy system. In certain embodiments, the
method can comprise operating a negative pressure source coupled to
a wound therapy dressing, where: the negative pressure source
comprises an inlet and an outlet; the inlet is in fluid
communication with the wound therapy dressing via a first conduit;
the outlet is in fluid communication with the wound therapy
dressing via a second conduit; the second conduit is in fluid
communication with a diverter valve; the diverter valve is
configured to allow a fluid flow from the negative pressure source
to atmosphere when the diverter valve is in a first position; and
the diverter is configured to allow a fluid flow from the negative
pressure source to the wound therapy dressing through the second
conduit when the diverter valve is in a second position. Certain
embodiments comprise operating the negative pressure source to
provide a negative pressure at the wound therapy dressing with the
diverter valve in the first position; and manipulating the diverter
valve from the first position to the second position.
[0013] In particular embodiments, the fluid flow can purge an
obstruction from either the first or second conduit when the
diverter valve is in the second position. Certain embodiments can
further comprise detecting the pressure of the first conduit via a
first pressure sensor. Specific embodiments further comprise
detecting the pressure of the second conduit via a second pressure
sensor. In certain embodiments, manipulating the diverter valve
from the first position to the second position can be performed
when the pressure of the first or second pressure sensor reaches a
first predetermined value. In particular embodiments, manipulating
the diverter valve can be performed automatically by an electronic
control circuit. In certain embodiments, the diverter valve can
comprise a piezoelectric valve.
[0014] In particular embodiments, the negative pressure source can
comprise a vacuum pump. Particular embodiments, can further
comprise manipulating the diverter valve from the second position
back to the first position. Certain embodiments further comprise
repeatedly manipulating the diverter valve between the first and
second positions.
[0015] Specific embodiments further comprise detecting the pressure
in the first or second conduit, and wherein manipulating the
diverter valve from the second position back to the first position
is performed when the pressure in the first or second conduit
reaches a second predetermined value.
[0016] 20. A tangible computer readable medium comprising computer
readable code that, when executed by a computer, causes the
computer to perform operations comprising the steps set forth in
claims 9-19.
[0017] Exemplary embodiments of the present disclosure comprise a
valve placed at the outlet (e.g., positive pressure side) of a
negative pressure source in an NPWT system. In certain embodiments,
the valve can either channel the flow to atmosphere (e.g, via a
silencing device) or divert some or all of the flow to the wound
pressure sensing channel. During normal negative pressure therapy,
the valve can be set to the exhaust position. When a blockage is
detected or suspected (or during instillation) the negative
pressure in the system can be relieved and the valve can be used in
combination with the negative pressure source to circulate air
through a sensing channel (thus clearing any blockage in the
sensing lumen) to the connector pad of a wound dressing and then
back through the therapy line and canister/reservoir.
[0018] In exemplary embodiments, air is not added to the system and
the dressing will not become pressurized. Matter or obstructions
caught in the sensing or therapy channels can eventually be
collected in the reservoir, which may incorporate a fluid/air
separation membrane.
[0019] The level of pressure utilized in exemplary embodiments can
be varied depending on the conditions. A blockage may require a
higher level of pressure whereas maintaining open sensing lines
during instillation may require less pressure.
[0020] In certain embodiments the reservoir can be vented to
atmosphere (using an additional valve, not shown) during the
instillation cycle, to avoid pulling the instillation fluid from
the wound site. The outlet valve can be used to allow the negative
pressure source (e.g., a vacuum pump) to pull atmospheric air
through the pump and provide a slight positive pressure through the
wound pressure sensing lines to prevent instillation fluid from
entering the lines.
[0021] In certain embodiments utilizing a multiple-patient-use
therapy device, microbial filters may be incorporated to the system
for recirculating air through the multiple-patient-use negative
pressure source. Alternatively, the negative pressure source
exhaust could be used to drive an isolation diaphragm to indirectly
pump positive pressure into the wound dressing from a filtered
ambient source.
[0022] Exemplary embodiments of the present disclosure comprise
numerous advantages over existing systems. For example, exemplary
embodiments are configured to clear fluid lines without applying
high pressures to the wound site, as well as to avoid the use of a
high negative pressure pump source to try to clear an obstruction.
Furthermore, exemplary embodiments are configured to decrease the
likelihood of fluid entering a pressure sensing line during
instillation. Finally, exemplary embodiments are configured to
regulate the air recirculation path (e.g. with a variable valve at
the pump exhaust), in order to maintain wound vacuum in the
presence of dressing leaks.
[0023] Other features and associated advantages will become
apparent with reference to the following detailed description of
specific embodiments in connection with the accompanying
drawings.
[0024] The term "coupled" is defined as connected, although not
necessarily directly, and not necessarily mechanically. The terms
"a" and "an" are defined as one or more unless this disclosure
explicitly requires otherwise.
[0025] The term "substantially" and its variations are defined as
being largely but not necessarily wholly what is specified as
understood by one of ordinary skill in the art, and in one
non-limiting embodiment "substantially" refers to ranges within
10%, preferably within 5%, more preferably within 1%, and most
preferably within 0.5% of what is specified.
[0026] The terms "comprise" (and any form of comprise, such as
"comprises" and "comprising"), "have" (and any form of have, such
as "has" and "having"), "include" (and any form of include, such as
"includes" and "including") and "contain" (and any form of contain,
such as "contains" and "containing") are open-ended linking verbs.
As a result, a method or device that "comprises," "has," "includes"
or "contains" one or more steps or elements possesses those one or
more steps or elements, but is not limited to possessing only those
one or more elements. Likewise, a step of a method or an element of
a device that "comprises," "has," "includes" or "contains" one or
more features possesses those one or more features, but is not
limited to possessing only those one or more features. Furthermore,
a device or structure that is configured in a certain way is
configured in at least that way, but may also be configured in ways
that are not listed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The following drawings form part of the present
specification and are included to further demonstrate certain
aspects of the present invention. The invention may be better
understood by reference to one or more of these drawings in
combination with the detailed description of specific embodiments
presented herein.
[0028] FIG. 1 is a schematic block diagram illustrating one
embodiment of a system purging an NPWT system in a first mode of
operation.
[0029] FIG. 2 is a schematic block diagram of the embodiment of
FIG. 1 in a second mode of operation.
[0030] FIG. 3 is a flowchart illustrating a series of steps that
can be performed in one embodiment of a method for purging an NPWT
system.
DETAILED DESCRIPTION
[0031] Various features and advantageous details are explained more
fully with reference to the nonlimiting embodiments that are
illustrated in the accompanying drawings and detailed in the
following description. Descriptions of well-known starting
materials, processing techniques, components, and equipment are
omitted so as not to unnecessarily obscure the invention in detail.
It should be understood, however, that the detailed description and
the specific examples, while indicating embodiments of the
invention, are given by way of illustration only, and not by way of
limitation. Various substitutions, modifications, additions, and/or
rearrangements within the spirit and/or scope of the underlying
inventive concept will become apparent to those skilled in the art
from this disclosure.
[0032] In the following description, numerous specific details are
provided, such as examples of programming, software modules, user
selections, network transactions, database queries, database
structures, hardware modules, hardware circuits, hardware chips,
etc., to provide a thorough understanding of the present
embodiments. One skilled in the relevant art will recognize,
however, that the invention may be practiced without one or more of
the specific details, or with other methods, components, materials,
and so forth. In other instances, well-known structures, materials,
or operations are not shown or described in detail to avoid
obscuring aspects of the invention.
[0033] FIGS. 1-2 illustrate one embodiment of a system 100 for
purging and providing fluid delivery to a negative pressure wound
therapy system. In the exemplary embodiment shown, system 100
includes a reservoir 110, a wound dressing 120 coupled to a wound
122, and a negative pressure source 130 comprising an inlet 132 and
an outlet 134. In this embodiment, negative pressure source 130 is
coupled to, and in fluid communication with, reservoir 110 and
wound dressing 120 via first conduit 135. During operation of
system 100, reservoir 110 can be used to capture wound fluids.
[0034] In particular exemplary embodiments, negative pressure
source 130 may comprise a diaphragm vacuum pump, a piezoelectric
pump, or a micro-pump, including those sold under the Vortis.TM.
brand name. In certain embodiments, system 100 may also comprise a
filter or muffler 137 coupled to negative pressure source 130 to
reduce the operating noise of negative pressure source 130 and/or
filter air exiting negative pressure source 130.
[0035] Certain exemplary embodiments, may also comprise a fluid
flow device (not shown), e.g. comprise a peristaltic, centrifugal
or other suitable pump, to provide instillation fluid to wound
dressing 120. In other exemplary embodiments, a fluid flow device
may comprise a gravity feed system instead of (or in conjunction
with) a pump to deliver fluid to wound dressing 120.
[0036] The exemplary embodiment shown in FIGS. 1-2 also comprises a
pressure sensor 160 coupled to, and in fluid communication with,
wound dressing 120 via a second conduit 165. In certain
embodiments, portions of second conduit 165 may be referred to as a
"pressure sensing line", and portions of first conduit 135 may be
referred to as a "therapy line".
[0037] The disclosed embodiment further comprises a diverter valve
140 configured for manipulation from a first position to a second
position. In certain embodiments, diverter valve 140 may comprise a
piezoelectric valve or solenoid valve. In particular embodiments,
diverter valve 140 may be manipulated automatically via an
electronic control circuit. In certain embodiments, valve 140 may
be a manually operated valve, and system 100 may comprise an input
control for valve 140.
[0038] In this exemplary embodiment, diverter valve 140 is
configured to allow a fluid flow (e.g. air flow) from the negative
pressure source to atmosphere when diverter valve 140 is in the
first position. In addition, diverter valve 140 is configured to
allow a fluid flow (e.g., air flow) from the negative pressure
source to the wound therapy dressing (via second conduit 165) when
the diverter valve is in a second position. In certain embodiments,
diverter valve 140, can be placed in a plurality of positions from
fully open to fully closed, as well as partially-open intermediate
positions between the fully open and fully closed positions.
[0039] Referring specifically to FIG. 1, arrows A-E indicate the
direction of fluid flow (e.g. air and/or instillation fluid) when
diverter valve 140 is in the first position and negative pressure
source 130 activated. As shown in this embodiment, fluid flows from
wound 122 through wound dressing 120 (indicated by arrow A), into
conduit 135 (arrow B) and then reservoir 110. From reservoir 110,
fluid flows into inlet 132 of negative pressure source 130
(indicated by arrow C) and exits from outlet 134 (indicated by
arrow D). At this point in the system, diverter valve 140 directs
the fluid flow to atmosphere (indicated by arrow E) through filter
or muffler 137. With diverter valve 140 in the position shown in
FIG. 1, fluid flow is restricted from conduit 165 and pressure
sensor 160.
[0040] Referring now specifically to FIG. 2, arrows B-G indicate
the direction of fluid flow (e.g. air and/or instillation fluid)
when diverter valve 140 is in the second position and negative
pressure source 130 activated. Similar to the embodiment shown in
FIG. 1, fluid flows from wound dressing 120 through conduit 135
(indicated by arrow B) and into reservoir 110. From reservoir 110,
fluid (e.g. air) flows into inlet 132 of negative pressure source
130 (indicated by arrow C) and exits from outlet 134 (indicated by
arrow D). At this point in the system, diverter valve 140 has been
moved from the first position shown in FIG. 1 to the second
position shown in FIG. 2. In the second position, diverter valve
140 directs fluid flow to conduit 165, pressure sensor 160 and
reservoir 110 (indicated by arrow F). From this point, fluid flow
is directed to wound dressing 120 (indicated by arrow G). When
fluid flow reaches wound dressing 120, it then travels through
wound insert 120 to conduit 135 (indicated by arrow H). At this
stage, fluid flow enters first conduit 135 (indicated by arrow B)
and the fluid flow cycle is repeated.
[0041] In exemplary embodiments, the fluid flow cycle shown and
described in FIG. 2 can be continued for the desired duration.
Wound dressing 120, or other components such as conduits 135 and
165, can be cleared of obstructions due to the changes in fluid
flow and/or pressure resulting from the manipulation of diverter
valve 140. In exemplary embodiments, obstructions cleared from
system components can be collected in reservoir 110, allowing a
clear path for fluid flow through system 100. It is understood that
certain embodiments may not include certain components illustrated
in FIGS. 1 and 2, e.g. reservoir 110 or pressure sensor 160. In
certain embodiments, negative pressure source 130 may comprise an
internal reservoir configured to collect obstructions cleared from
system 100.
[0042] In certain embodiments, diverter valve 140 can be
manipulated back and forth between the positions shown in FIGS. 1
and 2 in order to cyclically vary the fluid flow and/or pressure
throughout system 100. In certain embodiments, diverter valve 140
can be held in an intermediate position to maintain a low flow of
air through conduit 165.
[0043] The schematic flow chart diagrams that follow are generally
set forth as logical flow chart diagrams. As such, the depicted
order and labeled steps are indicative of one embodiment of the
presented method. Other steps and methods may be conceived that are
equivalent in function, logic, or effect to one or more steps, or
portions thereof, of the illustrated method. Additionally, the
format and symbols employed are provided to explain the logical
steps of the method and are understood not to limit the scope of
the method. Although various arrow types and line types may be
employed in the flow chart diagrams, they are understood not to
limit the scope of the corresponding method. Indeed, some arrows or
other connectors may be used to indicate only the logical flow of
the method. For instance, an arrow may indicate a waiting or
monitoring period of unspecified duration between enumerated steps
of the depicted method. Additionally, the order in which a
particular method occurs may or may not strictly adhere to the
order of the corresponding steps shown.
[0044] FIG. 3 illustrates one embodiment of a method 200 for
purging a negative pressure wound therapy system. Method 200
comprises a series of steps that may be executed for the operation
of an exemplary system according to this disclosure. Certain
embodiments may comprise a tangible computer readable medium
comprising computer readable code that, when executed by a
computer, causes the computer to perform operations comprising the
steps disclosed in FIG. 3.
[0045] Step 210 comprises positioning a diverter valve coupled to
the outlet of the negative pressure source to exhaust fluid flow
from the outlet of the negative pressure source to atmosphere. In
this exemplary embodiment, step 220 comprises activating a negative
pressure source in a negative pressure wound therapy system to
create negative pressure on a wound dressing. Step 230 comprises
manipulating the position of the diverter valve to direct fluid
flow from the exhaust of the negative pressure system to the wound
dressing. Step 240 comprises allowing fluid flow to recirculate in
the negative pressure wound therapy system. Step 250 comprises
manipulating the position of the diverter valve to direct fluid
from the exhaust of the negative pressure source to the wound
dressing to purge any blockage in the pressure sensor line. The
control cycle repeats as needed with Step 230 to maintain desired
wound vacuum.
[0046] All of the methods disclosed and claimed herein can be made
and executed without undue experimentation in light of the present
disclosure. While the systems and methods have been described in
terms of preferred embodiments, it will be apparent to those of
skill in the art that variations may be applied to the methods and
in the steps or in the sequence of steps of the method described
herein without departing from the concept, spirit and scope of the
invention. In addition, modifications may be made to the disclosed
system, and components may be eliminated or substituted for the
components described herein where the same or similar results would
be achieved. For example, rather than a diverter valve on the
outlet of the negative pressure source, one or more check valves
could be utilized along with a negative pressure source configured
to provide reversible fluid flow.
[0047] All such similar substitutes and modifications apparent to
those skilled in the art are deemed to be within the spirit, scope,
and concept of the invention as defined by the appended claims.
* * * * *