System, method, and pump to prevent pump contamination during negative pressure wound therapy

A pump assembly suitable for negative pressure wound therapy that includes an internal filter for preventing contamination in various components of the pump assembly, such as the pump unit. The internal filter is located in an isolated filter chamber, and inlet vacuum tubing that could contain fluids or bacteria are located inside a double containment sleeve to prevent contamination of components of the pump. The inlet vacuum tubing may be removed without opening the main pump housing and without contaminating the contents of the pump housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to the field of negative pressure wound therapy pumps. In particular, the present invention is directed to a method and apparatus for protecting a medical vacuum pump from contamination.

2. Brief Description of Related Art

Medical vacuum pumps are used in a variety of applications, including, for example, wound drainage and negative pressure wound therapy. Because the medical vacuum pumps often pull fluids from wounds, external collection canisters are used to collect the liquids before the liquids reach the pump itself. Similarly, filters can be placed between the collection canister and the pump to prevent liquids and bacteria from reaching the pump. The canister and filter, thus, reduce the opportunity for liquid fluids and bacteria to enter the pump and contaminate the pump.

If the internal components of a pump motor become contaminated with fluids or bacteria, the pump may not be used for any other patients for fear of cross-contamination and infection. The external filter and collection canister provide a degree of protection against contamination. Improper use of the pump, such as failing to use the external filter, however, can significantly increase the probability of pump contamination.

The tubing from the wound site to the collection canister and external filter may be the same diameter as the tubing from the canister or filter to the vacuum port inlet on the pump. Thus it is possible to connect the tubing from the wound site directly to the pump, thus bypassing the filter and canister. Similarly, the canister could be connected directly to the pump without the filter. A problem arises if the external filter is not installed during operation. The pump could ingest fluid when the filter is not installed, resulting in contamination of the pump.

Furthermore, in some applications, the user may choose not to use an external filter. Unfortunately, internal filters may be difficult to use because they require the entire pump housing to be opened to reach the filter. It is desirable to have an internal filter, that is easy to use, that can reliably protect a pump regardless of operator error.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present invention, a pump has an internal filter to be used in conjunction with an external filter. The internal filter is located inside a filter chamber. The filter chamber is isolated from the interior of the pump housing and thus the filter can be accessed without opening the pump housing. A vacuum port is located on the exterior of the pump housing for connecting the pump to tubing or directly to a collection canister. The vacuum port comprises a removable nipple located inside a bushing. An inlet tube forms a passage between the inlet nipple and the internal filter. An outer containment tube is attached to the bushing and to a bushing on the filter chamber. The inlet tube is located inside the outer containment tube, thus preventing contamination from the inlet tube from contacting other components of the pump.

Should the internal filter become contaminated, in an example embodiment, the pump will stop functioning until the filter is replaced. To replace the filter, in an example embodiment, a technician disconnects any external tubing, opens the filter chamber, cuts or disconnects tubing attached to the filter, removes the inlet nipple from the bushing, and pulls the inlet tube out through the bushing. The technician then attaches a new inlet tube to a new inlet nipple, feeds the inlet tube through the bushing and outer containment tube to the filter chamber, attaches the inlet tube to the inlet side of a new filter, attaches the filter outlet tube to the outlet of the new filter, secures the nipple in the bushing, and replaces the cover on the filter chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIG. 1, shown in a perspective view is an example embodiment of a vacuum pump assembly100that includes a pump housing102. Pump housing102can be a rigid shell that houses the components of the vacuum pump assembly100and may be made of plastic, metal, or any other suitable material. In some embodiments, the pump housing102serves as a frame for supporting other components of the vacuum pump assembly100, such as a vacuum pump motor, filter, electronic controls104, etc. In other embodiments, a frame (not shown) is located within the housing102to support the various components. The pump housing102may have various openings such as air outlets, vents, and vacuum ports106for attaching tubes108. In some embodiments, the exterior of the pump housing102may have a handle110. The exterior of the pump housing102may have brackets112(FIG. 2) that could be used to affix the pump housing102to another device or frame, or to attach a device such as a collection canister114to the pump housing102.

Still referring toFIG. 1, collection canister114may be in fluid communication with the vacuum port106via external connection tube108. In some embodiments, collection canister114has a float valve (not shown) for stopping the flow of air when the fluid level reaches a predetermined point. Collection canister114may also have an inlet port116, an outlet port118, and an access point120with a cap.

In an example embodiment, external connection tube108is a pliable tubing that is sufficiently rigid such that it does not collapse on itself when subjected to vacuum pressures. One end of external connection tube108engages fitting118on collection canister114while the other end engages vacuum port106. In some embodiments, collection canister114is attached directly to pump housing102. In some embodiments (not shown), collection canister114may have a fitting that connects directly to vacuum port106, thus not requiring an external tube between collection canister114and vacuum port106.

In some embodiments, external filter121is located in-line on external connection tube108. External filter121may comprise a housing and filter element (not shown). The filter element may include a hydrophobic bacterial material capable of preventing liquid or bacteria from passing through the external filter121, yet still allowing gas, i.e. air, flow therethrough. In some embodiments, external filter121has different colors on each side of the housing such that, for example, external filter housing is clear on the side facing collection canister, and blue on the side facing vacuum pump assembly100. In some embodiments, external filter121may be located inside canister114. Filter121may block all flow after becoming saturated or absorbing a predetermined amount of liquid.

An upward looking view of the pump assembly100is provided inFIG. 3; in this embodiment a filter chamber124is shown located within pump housing102and containing filter assembly126. In an exemplary embodiment, the filter chamber124is a compartment within the housing102having rigid upper and side chamber walls128above and along the outer periphery of the filter chamber124thereby separating the contents of the filter chamber124from the other components of the pump assembly100.

As will be described in more detail below, the components inside filter chamber124, such as filter assembly126, may be replaced without opening pump housing102to expose other components located inside pump housing102(such as pump motor and electronics). In some embodiments, the filter chamber124is hermetically sealed. In other embodiments, the chamber124generally isolates the contents of the chamber from the interior of the pump housing102, but may have openings between the chamber124and the pump housing102. The openings could be, for example, used to secure tubing130shown connected between an outlet connection162of the filter assembly126outlet to a passage formed through the upper chamber wall128. Tubing130may be secured to the inside of the chamber124slide fasteners132shown inserted through holes in the upper chamber wall128and around tubing130. The filter chamber124may be integral to the pump housing102, or it may be a separate chamber (not shown) attached to the pump housing102. The filter assembly126ofFIG. 3also includes an inlet connection160that provides fluid communication between the filter assembly126and an inlet tube138.

Referring toFIG. 4, filter chamber124may be covered by a door or a cover134, thus enclosing the chamber124. The door or cover134may be opened to allow access to the internal filter assembly126(FIG. 3) and the inside of the filter chamber124. In some embodiments, the door or cover134detaches from the pump housing102or chamber124upon opening. In other embodiments, the door or cover134remains attached to the housing102or chamber124, such as by hinges or by slidingly engaging the housing102, when the door or cover134is moved to the open position. In some embodiments, filter chamber124is not considered “user accessible” and thus filter replacement requires an authorized technician to open filter chamber cover134. Access to internal filter unit126can be limited by, for example, using a locking device135to secure cover134. Locking device can be, for example, a screw that requires a tool to open. In one embodiment, the tool to open could be a hex-key or other tool that an unauthorized user is not likely to have. In an alternative embodiment, locking device135is a lock that requires a key to open. In these embodiments, a person authorized to open cover134such as, for example, a pump service technician, will have the key or tool required to open. Unauthorized users, thus, are prevented from opening cover134.

Referring toFIG. 5, an example embodiment of the pump assembly100is shown in a side partial sectional view revealing certain components within the pump housing102. In this view an outer sleeve136is a generally cylindrical tube that forms a passage between an opening145in the pump housing102, through the interior of the pump housing102, to an opening147in the upper wall of the filter chamber124. The ends of the outer sleeve136are shown attached to bushings140,137respectively provided in openings145,147. The outer sleeve136may be generally straight or may have longitudinal curves to facilitate the efficient placement of components inside the pump housing102. Outer sleeve136may be made of a rigid material, such as hard plastic or metal, or a pliable material such as tubing. In an example embodiment, the outer sleeve136has sufficient thickness to retain fluids therein and the outer sleeve136couplings at the ends of the outer sleeve136form hermetic seals. Thus, any liquids or bacteria that are released inside the outer sleeve136will generally remain inside outer sleeve136or drip into filter chamber124without contaminating any components within the pump housing102.

Some embodiments may not use an outer sleeve136. In these embodiments (not shown), filter inlet tube138passes directly into filter chamber124without passing through any other part of the interior of pump housing102.

The vacuum port106ofFIG. 5is a fitting on the exterior of the pump housing102that can be used for attaching external connection tube108to the pump assembly100. In addition to the bushing140, the vacuum port106includes a vacuum port nipple142shown above and coaxial to the bushing140. The bushing140can be secured to the housing102by a nut144illustrated located inside housing102and a flange146, shown located outside housing102. In an exemplary embodiment, outer sleeve136slides over bushing140. Optionally, the inner diameter of outer sleeve136may be smaller than the outer diameter of bushing140, resulting in a force fit. A hose clamp (not shown) may be used to secure outer sleeve136to bushing140. The inner diameter of bushing140, at the opposite end of bushing140from where outer sleeve attaches, may have slots or threads for receiving locking tabs150(FIG. 6A) or threads of nipple142.

Referring toFIGS. 6Aand B, respectively shown in a side view in phantom lines and in a plan view, is an example embodiment of the vacuum port nipple142having a passage152formed axially therethrough. As shown inFIGS. 6A and 6B, the passage152outer periphery defines a hexagonal pattern with flat surfaces for receiving a tool such as an Allen wrench (also known as a hex-key). In an exemplary embodiment, when the external connection tube108(FIG. 1) is not attached, vacuum port nipple142may be rotated with Allen wrench thus removing nipple142from bushing140. Nipple142, thus, has an attached position wherein it engages and is concentrically located in bushing140, and a detached position when it is disengaged from bushing140.

In an example embodiment, vacuum port nipple142attaches to bushing140(FIG. 5) via quarter-turn tabs150or threads (not shown) located on the outside of vacuum port nipple142. Vacuum port nipple142may have a flange154wherein the outer diameter of flange154can be roughly the same as the outer diameter of flange146of bushing140. Vacuum port nipple142can have a smooth outer diameter (“OD”) surface156for engaging the inner diameter (“ID”) of internal inlet tube138. The connection between inlet tube138and nipple142, thus, is a frangible connection. Other means of attaching vacuum port nipple142to bushing140may be used. Vacuum port nipple142may also have a smooth outer diameter surface158that protrudes outward from housing102for engaging vacuum tube108. In one embodiment, an operator can manually engage and disengage vacuum tube108from vacuum port nipple142. Vacuum port nipple142may be configured to be rotated by any of a variety of tools or by hand. In some embodiments, vacuum port nipple142may comprise an orifice (not shown) wherein vacuum tube108or a fitting on collection canister114is inserted into the orifice. Thus the inner diameter of vacuum port nipple142will engage the outer diameter of vacuum tube108or collection canister fitting (not shown).

Referring now toFIG. 8, a side partial sectional view of an embodiment of the pumping assembly100is illustrated depicting the internal inlet tube138in phantom passing from vacuum port nipple142, through outer sleeve136, to filter assembly126. Internal inlet tube138is a tubing that is generally pliable such that it can bend within outer sleeve136, but is sufficiently rigid that the walls of internal inlet tube138will not collapse when suction is applied to the tube. Inlet tube138is contained inside outer sleeve136. If inlet tube138leaks any fluid, the fluid will be contained in outer sleeve136. Furthermore, inlet tube138is not exposed to the internal components of pump assembly100and thus inlet tube138can be removed without contacting any internal components of pump assembly100. Internal inlet tube138can have cutting point159, which is a point along inlet tube138located axially below outer diameter surface156of nipple142. Cutting point159is a point wherein inlet tube138may be severed to allow removal of a portion of inlet tube138and filter assembly126, as a module. Cutting point159, thus, can be considered a frangible connection along inlet tube138.

Referring now toFIG. 5, in an example embodiment, the filter assembly126is made up of a filter element161located inside a housing163. In an example, the filter element161includes hydrophobic bacterial material. As indicated above, filter assembly126has in inlet connection160and an outlet connection162, where the inlet tube138can forcibly slide over inlet connection160, forming a seal. The connection can be such that an operator can manually engage and disengage inlet tube138from inlet connection160. Similarly, an operator can manually engage and disengage outlet tube130from outlet connection162. The engagement between inlet tube138and inlet connection160, thus, is a frangible connection. Likewise, the engagement between outlet connection162and internal pump tube130is a frangible connection. In an example embodiment, gas or vapor is flowable through the filter element161, but fluid and bacteria is trapped within. In the event filter element126becomes saturated with liquid and/or bacteria, or absorbs a predetermined amount of liquid, all flow, i.e. gas, liquid, and bacteria, is blocked.

Referring toFIG. 7, a side partial sectional view of an example pump assembly100depicts the internal pump tube130attached to outlet connection162on filter assembly126. Internal pump tube130may be made of a generally pliable tubing, wherein the tubing is sufficiently rigid that it will not collapse when vacuum is applied. Internal pump tube130forms a pathway from filter outlet connection162to a pump inlet164. In some embodiments, a single tube (not shown) connects outlet connection162to pump inlet164. In other embodiments, internal pump tube130may attach to a fitting such as right-angle fitting166. In this embodiment, a second tube168may connect from the right-angle fitting166to pump inlet164.

The pump inlet164distal the outlet connection162is illustrated coupled to a vacuum170. In the embodiment ofFIG. 7, the vacuum pump170can be a conventional medical grade vacuum pump capable of generating suction. In an exemplary embodiment, vacuum pump170may generate vacuum pressure up to 200 mmHg and have an air flow rate of 5-20 liters per minute. Fluid received by the vacuum pump170through the pump inlet164is pressurized and delivered to a pump outlet172. In an exemplary embodiment, pump outlet172exhausts through an exhaust port174(FIG. 3) shown formed through the pump housing102below the vacuum pump170. Pump outlet172may exhaust elsewhere such as, for example, into the interior of pump housing102, provided that pump housing102has an exhaust vent.

From time to time it may be desired or necessary to replace the filter assembly126; which can be accessed via the filter chamber cover134(FIG. 4). Referring back toFIG. 8, a cavity176inside pump housing102, that defines a space where the vacuum pump170and components are located, can remained sealed when the filter assembly126is replaced or otherwise serviced. Thus the components of pump assembly100located within cavity176are not disturbed during replacement/service of the filter assembly126. Furthermore, during filter replacement, the risk of contaminant exposure is limited to the interior of filter chamber124and the interior of sleeve136. Components such as the pump170, electronic controls104(FIG. 1) and batteries178(FIG. 5) are not exposed to fluids and contaminants, regardless of whether fluids entered the vacuum port106and reached filter assembly126.

For the purposes of discussion herein, negative pressure wound therapy (“NPWT”) can describe applying negative pressure to a wound site. In an example, vacuum pump assembly100(FIG. 1) is used to create negative pressure for NPWT where values of the negative pressure may be constant or variable. In some embodiments, value of negative pressure range from, for example, about −20 mm/Hg to about −80 mm/Hg.

Referring toFIG. 9, in an exemplary embodiment, a NPWT dressing180is shown in a side sectional view and including a dressing medium182, such as fluffed gauze or foam, which is placed on a wound bed184. A drain188, such as Prospera® Round Channel or perforated Flat Drain can be placed above dressing medium182. Other types of dressings and drains may be used. Dressing tubing122is attached from the end of drain188to vacuum canister inlet116(FIG. 1). A semi-permeable wound dressing cover192, such as Tegaderm®, Opsite®, or Bioclusive®, is placed over the dressing to form a seal over the wound cavity. The semi-permeable wound dressing cover192adheres or is attached to healthy skin194surrounding wound bed184. Other types of dressing covers may be used.

In an example of operation, vacuum pump assembly100is used to generate suction for a NPWT dressing180by creating a pressure differential between the wound bed184and drain188that draws fluids and bacteria from the wound, through Dressing tubing122, through fitting116, and into canister114. Under normal operating conditions, canister114is emptied before it is completely full and thus fluid and bacteria does not enter external filter121or internal filter assembly126. Should fluids enter external filter121, external filter121will become partially blocked or completely blocked, causing pump170to shut off.

Under some operating conditions, liquid from a wound may be able to enter pump assembly100. This could occur if components are missing or damaged. For example, the collection container114or external filter121could be damaged or a health-care provider could inadvertently bypass collection container114and filter121, resulting in vacuum line122being connected directly to external fitting106(FIG. 2). If liquid from a wound or bacteria passes through vacuum port nipple142, the liquid and/or bacteria will travel through filter inlet tube138, through filter inlet160, and become trapped inside internal filter assembly126. Like external filter121, internal filter assembly126will become partially or completely blocked when it is saturated with liquid.

Pump170and/or vacuum lines associated with pump170may be equipped with sensors (not shown) for detecting flow or pressure during operation. In the event either filter121,126(FIG. 5) becomes blocked due to saturation, or flow to pump170is stopped for any other reason, a sensor will cause the pump to alarm, stop, or both alarm and stop. In an exemplary embodiment, electronic controls deactivate pump170when sensors measure a change in pressure or flow characteristics. In an exemplary embodiment, pump170will stop before any liquid and/or bacteria bypasses internal filter.

A flowchart is provided inFIGS. 10A-10Billustrating an example embodiment of a process of operation of the vacuum pump assembly100. In the event the internal filter assembly126becomes contaminated or simply needs routine replacement, a health-care professional or technician can disconnect the external tube108from the inlet106, as shown in step200. In some embodiments, filters may be replaced after a predetermined amount of time such as, for example, 1000 hours of pump use. The filter chamber cover134can be opened, such as by a technician, to expose the filter assembly126(step202). The filter outlet tube130can be disconnected from filter outlet160or from the right-angle connection166in step204. In an exemplary embodiment, the filter outlet tube130remains uncontaminated because the filter assembly126prevents contamination from entering the filter outlet tube130. Shown in step206, the filter inlet tube138can be disconnected by detaching the filter inlet tube138from the filter inlet162or by cutting the filter inlet tube138. A plug, cap, or clamp (not shown) can be installed on the end or ends of the filter inlet tube138to contain any contamination inside the tube. When both tubes130,138are removed or severed, filter assembly126may be removed from filter chamber124(step208).

An Allen wrench may be used to turn nipple142to release it from bushing140in step210. Once nipple142is released from bushing140, nipple142and filter inlet tube138may be pulled out of pump assembly100, as indicated by step212. Sleeve136remains in place. At this point, filter chamber124and the interior of outer sleeve136is accessible and may be cleaned by conventional means, such as disinfectant wipes or swabs in step220.

To install a new filter, a new filter inlet tube138can be attached to a new nipple142(step224) and then the new filter inlet tube138can be slid through outer sleeve136and into contact with the filter chamber228(step226). In some embodiments, inlet tube138and nipple142are pre-assembled. As indicated by step228, the filter inlet tube138may be pulled from the filter chamber124until the end is at the desired position and nipple142contacts bushing140. The end of filter inlet tube138can then be attached to a new filter assembly126(step230) and the filter outlet tube130attached to new filter assembly126, and new filter assembly126can be placed inside filter chamber124(step232). Nipple142can be secured inside bushing140as shown in steps234and236. The filter chamber cover134can be closed and secured in place in step238. In some applications, filter cover134may be locked to prevent unauthorized access. Pump assembly100is now in condition for continued use or use with a different patient. If pump assembly100was returned to a service center for filter replacement or was returned to supplier and supplier wishes to send to another user, the pump assembly100may be sent to user, such as health-care professional, in step240. The health-care professional can then attach, via tubing, an external filter121in step242, and then attach, via tubing, a collection canister in step244. The health-care professional may prepare a wound for drainage or suction in step246, and then attach Dressing tubing122from canister114to the prepared wound in step248. Finally, the health-care professional can activate the pump assembly100to apply suction to create negative pressure, as indicated by step250.

In some embodiments, a health care professional may attach external connection tube108, external filter121, and collection canister114to pump assembly100. The health care professional can create a NPWT wound dressing180and attach Dressing tubing122to canister114. Filter121may be located in a variety of places, such as within canister114or directly attached to pump vacuum port106. In some embodiments, filter121is not used.

Health care professional can then activate pump assembly100to create negative pressure at the wound site. The suction created by pump170is drawn through tube168, through filter outlet tube130, through filter assembly126, through filter inlet tube136, through external connection tube108, through external filter121, through canister114, through Dressing tubing122, to the NPWT dressing180. Air and gas drawn through the pathway and into pump170is discharged by, for example, passing through pump discharge tube172(FIG. 7), which may lead to exhaust port174(FIG. 3). In some embodiments, pump assembly100has variable pressure and cycles between various predetermined pressures.

Furthermore, recitation of the term about and approximately with respect to a range of values should be interpreted to include both the upper and lower end of the recited range. As used herein, the terms first, second, third and the like should be interpreted to uniquely identify elements and do not imply or restrict to any particular sequencing of elements or steps.

Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.

Optional or optionally indicates that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.