Negative pressure device including expandable segment

A negative pressure device for applying to skin is configured to define a sealed enclosed three-dimensional space when at least a portion of the device is sealed against the skin. The device includes a body including at least one expandable segment that is configured to expand after the device has been sealed against the skin.

BACKGROUND

Negative pressure is a term used to describe a pressure that is below normal atmospheric pressure. Known topical negative pressure devices range from cumbersome wrinkle reducing suction apparatuses to wound therapies that include fluid-permeable wound cavity filling elements, covering dressings, reasonably air-tight means for sealing against the skin, and drainage tubes connecting the wound site and cavity filling element to the vacuum source via a fluid collection canister.

To enable a more prolonged application of topical negative pressure, powered systems, which include a vacuum generation source such as a pump, have been developed and many examples of such systems are used today for skin treatments and restorative purposes like the temporary removal of wrinkles. Many of these systems, however, are not convenient for users. Such known systems can be large, heavy, noisy, uncomfortable, and not simple for users to apply and initiate a controlled pressure condition. Such known systems also rely on an outside power or vacuum source to create topical negative pressure conditions.

Such tissue treatment, surgery, and other advanced technical interventions are becoming more common given the occurrence of both the aging population, as well as increasingly compromised patient populations. This trend looks set to continue. In wound care, for example, healthcare professionals are now more likely to encounter wounds with complex healing problems that are difficult to manage. Attempts have been made to produce more simple mechanical devices able to apply topical and negative pressure to a tissue site. It will be appreciated that such a medical device, due to its relative simplicity of design, would be expected to reduce material costs and assembly costs. For example, attempts have been made to use a hand-pump system for the application of topical negative pressure at a tissue site. However, such a system fails to enable easier application by the user, discreet use, and prolonged convenient application of topical negative pressure, and, in fact, re-evacuation is often necessary. These can be serious deficiencies, particularly as many such systems are ideally useable for prolonged periods, such as overnight.

SUMMARY

In view of the foregoing, a negative pressure device for applying to skin is configured to define a sealed enclosed three-dimensional space when at least a portion of the device is sealed against the skin. The device includes a body including at least one expandable segment that is configured to expand after the device has been sealed against the skin.

DETAILED DESCRIPTION

FIG. 1depicts a negative pressure device100for applying to skin S. With reference toFIG. 2, the device100is configured to define a sealed enclosed three-dimensional space102when sealed against the skin S. Negative pressure, with relation to atmospheric pressure, can be achieved in the sealed enclosed three-dimensional space102.

The negative pressure device100includes a body106including at least one expandable segment108that is configured to expand after the negative pressure device100has been sealed against the skin S. The negative pressure device100is shown including a plurality of expandable segments108. Unless otherwise mentioned, if only one expandable segment108is being described, it is to be understood that each expandable segment108can be similarly constructed and operate in a similar manner.

In accordance with the ideal gas law, if the volume of the enclosed three-dimensional space102increases, then the gas pressure in the enclosed three-dimensional space102decreases when the same number of moles of gas is maintained in the enclosed three-dimensional space102. Accordingly, if the expandable segment108is allowed to expand so as to increase the volume of the enclosed three-dimensional space102, then the gas pressure within the enclosed three-dimensional space102decreases. As such, negative pressure (with respect to atmospheric pressure) can be applied to the skin S beneath the body106within the enclosed three-dimensional space102.

FIG. 2depicts the negative pressure device100including a pressure relief valve112on the body106. The pressure relief valve112is configured to provide selective pneumatic communication between ambient and the sealed enclosed three-dimensional space102. The pressure relief valve112is configured to open, thus providing communication between ambient and the sealed enclosed three-dimensional space102, in response to a compressive force (depicted as arrow114inFIG. 2) exceeding atmospheric pressure being applied to the expandable segment108. The pressure relief valve112is also configured to close, thus precluding communication between ambient and the sealed enclosed three-dimensional space102, in response to the compressive force exceeding atmospheric pressure being removed from the expandable segment108.

The expandable segments108are movable between a compressed state and an expanded state. When at least one of the expandable segments108is in the expanded state, which is depicted as expanded expandable segment108einFIG. 2, the volume of the sealed enclosed three-dimensional space102is greater than the volume of the sealed enclosed three-dimensional space102when the expandable segment108is in the compressed state, which is depicted in broken lines as compressed expandable segment108cinFIG. 2. As seen inFIG. 2, the expandable segment108moves toward the skin S, which is shown in broken lines inFIG. 2, when the compressive force exceeding atmospheric pressure is applied to the expandable segment108. The expandable segment108also moves away from the skin S when the compressive force exceeding atmospheric pressure is removed from the expandable segment108, thus returning to the configuration shown in solid lines inFIG. 2.

The body106or the expandable segment108is constructed of a material with sufficient strength and resiliency to expand back toward the state shown in solid lines inFIG. 2after 1-5 PSI of pressure above atmospheric pressure is applied to the expandable segment108. The expandable segment108can be configured to move away from the skin S when pressure acting against an external surface of the body106is up to 20% greater than an internal pressure in the sealed enclosed three-dimensional space102beneath the body106acting against an internal surface of the body. When the expandable segment108is depressed to the configuration shown in broken lines inFIG. 2, the pressure relief valve112opens and air within the enclosed three-dimensional space102is allowed to exit to ambient. When the force is removed from the expandable segment108, the pressure relief valve112closes. The expandable segment108, however, is made from a material such that it overcomes the downward force (per the orientation shown inFIG. 2) of the partial vacuum within the sealed enclosed three-dimensional space102so as to return to the state shown in solid lines inFIG. 2. Since air has been expelled from the sealed enclosed three-dimensional space102, fewer moles of air are present within the sealed enclosed three-dimensional space102and thus the gas pressure within the sealed enclosed three-dimensional space102is reduced as compared to prior to applying the force on the expandable segment108.

FIG. 3depicts another embodiment of a negative pressure device200for applying to skin S. The negative pressure device200is configured to define a sealed enclosed three-dimensional space202when sealed against the skin S. The negative pressure device200includes a body206including at least one expandable segment (a plurality of expandable segments208is depicted). The expandable segments208are configured to expand after the negative pressure device200has been sealed against the skin S.

In the embodiment depicted inFIG. 3, the negative pressure device200further includes a retaining structure212. As shown inFIG. 3, two retaining structures212are provided; however, a fewer or greater number of retaining structures212can be provided. Each retaining structure212connects with the body206or the expandable segments208such that the expandable segments208are compressed prior to removal of the retaining structure212from the body206or the expandable segments208to which the retaining structure212is connected. The retaining structure212can connect with the body206or the expandable segments208using an adhesive (not shown) or through a mechanical connection. The retaining structures212are typically connected with the body206or the expandable segments208prior to the negative pressure device200being sealed against the skin S, and then are removed after the negative pressure device200is sealed against the skin S.

FIG. 3shows one of the retaining structures212having been removed from the body206and another of the retaining structures212still connected with the body206. The retaining structures212are selectively removable from the body206or the expandable segments208. The expandable segments208are movable between the compressed state, which is shown for the expandable segments208cto which the retaining structure212is still connected inFIG. 3, and the expanded state in which the expandable segments208ehaving the retaining structure212removed is shown inFIG. 3. The expandable segments208are configured to move from the compressed state toward the expanded state after the retaining structure212is removed from the body206or the expandable segment208.

The negative pressure device200is affixed to the skin S around an apron216, which is provided around a periphery of the body. The apron216and the body206can be an integrally formed piece of material and the apron216is conformable to contours on the human body. A sealing element218is provided on the lower surface220of the apron216to define the sealed enclosed three-dimensional space202when the negative pressure device200is sealed against the skin S.

The expandable segments208are typically compressed by the retaining structure212when the negative pressure device200is affixed to the skin S. After the negative pressure device200is affixed to the skin S, one or all of the retaining structures212can be removed from the body206and the expandable segments208. The body206and/or the expandable segments208are made from a material with sufficient resiliency to overcome any partial vacuum in the sealed enclosed three-dimensional space202so as to expand from the position of the compressed expandable segments208cto the position of the expanded expandable segments208e. The expansion of the expandable segments208results in the volume of the sealed enclosed three-dimensional space202increasing. Since the same number of moles of air (or other gas) is present in the sealed enclosed three-dimensional space202, the gas pressure within the sealed enclosed three-dimensional space202reduces below that of atmospheric pressure. The pressure applied by each retaining structure212on each expandable segment208can be about 3 PSI above atmospheric pressure. As such, as the expandable segments208cmove from the compressed state to the expanded state, which is shown by the expandable segments208e, a reduction of 3 PSI within the sealed enclosed three-dimensional space202can occur, which can result in a relative negative vacuum within the sealed enclosed three-dimensional space202as compared to atmospheric pressure.

FIG. 4depicts another embodiment of a negative pressure device300for applying to skin S. The negative pressure device300is configured to define a sealed enclosed three-dimensional space302when sealed against the skin S. The device300includes a body306including at least one expandable segment308that is configured to expand after the device300has been sealed against the skin S.

FIG. 4shows one of the expandable segments, i.e., an expanded expandable segment308e, in an expanded state, and another of the expandable segments308c, i.e., a compressed expandable segment308c, in a compressed state. The negative pressure device300includes a biasing element, which is a spring312in the illustrated embodiment. The spring312connects with the body306or desired expandable segments308so as to bias the expandable segment308toward the expanded state.

The spring312can be part of a biasing assembly that includes a cam mechanism314that operates similarly to a conventional ball point pen mechanism. The cam mechanism314can mount to a support structure316, which can include openings320to allow for a pneumatic communication between an upper surface of the support structure316and the lower surface of the support structure. A cam318can mount to the support structure316. A follower322cooperates with the cam318. The follower322can include a base324and a stem326that connects the base324with the expandable segment308. The cam mechanism314associated with the spring312has a first state, which is shown for the cam mechanism314associated with the expanded expandable segment308e, and a second state, which is shown for the cam mechanism314associated with the compressed expandable segment308c.

When the negative pressure device300is applied to the skin S, each of the expandable segments308can be in the compressed state. An operator can then apply a force (downward per the orientation shown inFIG. 4) on each respective compressed expandable segment308c, which will result in the follower322cooperating with the cam318in a manner such that the spring312acting against the support structure316urges the follower322upward (per the orientation shown inFIG. 4) such that the compressed expandable segment308cmoves toward the expanded state, which is shown as the expandable segment308e. By allowing the expandable segments308to move from the compressed state toward the expanded state, the volume of the sealed enclosed three-dimensional space302is increased, which can result in a reduction in gas pressure within the sealed enclosed three-dimensional space302.

FIG. 4depicts the spring312biasing each expandable segment308away from the skin S after the negative pressure device300has been sealed against the skin S. In an alternative arrangement, the biasing direction of the spring312can be changed. For example, the spring312could be reconfigured to urge the expandable segment in a direction generally parallel with the skin S or in directions other than away from the skin S.

FIG. 5depicts another embodiment of a negative pressure device400for applying to skin S. The negative pressure device400is configured to define a sealed enclosed three-dimensional space402when sealed against the skin S. Similar to the embodiments described above, the negative pressure device400includes a body406and at least one expandable segment408that is configured to expand after the negative pressure device400has been sealed against the skin S. The expandable segments408inFIG. 5can be similar to the expandable segments108,208and308described inFIGS. 1-4.

The negative pressure device400can further include a pump for removing gas from the sealed enclosed three-dimensional space402. InFIG. 5, the pump is in the form of a reactor412that is configured to remove a selected gas from air. An example of such a reactor is described in US 2014/0109890 A1, which describes an oxygen based heater. The oxygen based heater, however, can be used as the reactor to consume oxygen within the sealed enclosed three-dimensional space402thus producing a partial vacuum within the sealed enclosed three-dimensional space402(i.e., a negative pressure condition). The reactor412may also be any combination of electro-chemical pumps, vacuum-on-demand devices (referred to herein as VOD), electrolyzers, pressure-reducing solid state devices, oxygen absorbing iron packets, getters of zirconium titanium, vanadium iron, lithium, lithium metal, magnesium, calcium, lithium barium combinations, zinc-air batteries, or other materials reactive with selective gases, for example, nitrogen, carbon dioxide, and oxygen gases found in air. Accordingly, the reactor412can be configured to consume oxygen, or the reactor can be configured to consume at least one non-inert gas.

FIG. 5depicts the reactor412disposed within the sealed enclosed three-dimensional space402beneath the body406.FIG. 6depicts and embodiment of a negative pressure device500similar in all respects to the negative pressure device400shown inFIG. 5, however, a reactor512, similar in all aspects to the reactor412described above, is instead in pneumatic communication with the sealed enclosed three-dimensional space502via an opening514in the body506. The reactor512can be disposed within a chamber516defined by a rigid container body518. The chamber516can be configured to maintain a pre-defined chamber volume, which can remain constant or a minimum predetermined volume, while the gas is being consumed from the enclosed three-dimensional space502by the reactor512. A pneumatic line522connects the chamber516to the sealed enclosed three-dimensional space502. The body506can include at least one expandable segment508that is configured to expand after the device500, and more particularly the body506, has been sealed against the skin S.

For the embodiments depicted inFIGS. 5 and 6only one reactor412,512is depicted. If desired, multiple reactors412,512can be provided with each respective negative pressure device400,500. The reactors412,512can be designed to operate at different scavenging speeds. When two or more reactors412,512are provided, one reactor412,512can be designed to pump down the gas pressure in the enclosed three-dimensional space402,502quickly, e.g., less than two minutes. A second (or other) reactor412,512can be activated at the same time, however, the second (or other) reactor412,512works more slowly. The slower working reactor412,512can designed to reduce the oxidation coating covering the reactor412,512allowing it work more effectively in low oxygen concentration. Where the reactor412,512is a VOD, the VOD can also be used to further pump down the enclosed three-dimensional space402,502to a therapeutic range if the oxygen level in the enclosed three-dimensional space402,502is depleted, working to remove other gases in the enclosed three-dimensional space402,502, primarily nitrogen.

FIG. 7depicts a reactor612disposed within a chamber616defined by a container body618. The chamber616can be configured to maintain a pre-defined chamber volume while the gas is being consumed from a sealed enclosed three-dimensional space, which can be the enclosed three-dimensional spaces102,202,302,302,502mentioned above, or a sealed enclosed three-dimensional space underneath a bandage drape, for example for the wound therapy devices described in WO 2017/075381 A1 or the controlled pressure devices described in WO 2017/075331 A1. The container body618can include at least one expandable segment608that can be configured to operate in the same manner as the expandable segments108,208,308,408,508. The chamber616can be connected for pneumatic communication with the enclosed three-dimensional spaces102,202,302,302,502mentioned above, the enclosed three-dimensional for the wound therapy devices described in WO 2017/075381 A1 or the enclosed three-dimensional for the controlled pressure devices described in WO 2017/075331 A1 via a fluid line622, which is schematically depicted inFIG. 7. The expandable segment608can expand, thus increasing the volume of the chamber616, after the device, which defines the aforementioned sealed enclosed three-dimensional space, has been sealed against the skin S.

The enclosed three-dimensional spaces102,202,302,302,502include an air volume portion occupied by air trapped in the respective enclosed three-dimensional space. In the case of a therapeutic negative pressure system, utilized for wound care, the range of reported operating pressures, relative to standard atmospheric pressure of 760 mmHg, are from −60 mmHg to −200 mmHg (absolute pressures of 560 to 700 mmHg). When using a reactor512,612configured to consume oxygen, after all of the molecules of oxygen have been consumed by the reactor from the air in the overall system volume, the gas pressure in the overall system volume is reduced by 21% (or 159.6 mmHg) assuming that the overall system volume was to remain constant. Thus, with the ideal case delivering maximum potential of −159.6 mmHg with dry air (note that the presence of humidity can change this number), designing a system to deliver the correct operating pressure, accounting for changes in the volume of the enclosed three-dimensional spaces102,202,302,302,502and exudate entering any wicking material and displacing air, is a formidable task.

The negative pressure devices inFIGS. 6 and 7accomplish this task by dividing the negative pressure system into two volumes: the trapped air in the enclosed three-dimensional spaces102,202,302,302,502(or under a bandage), which is referred to as V1, and the chamber volume of each chamber516,616, which is referred to as V2. For example, if the chamber616is connected with a bandage, the bandage is flexible and absorbs fluid (exudate) as necessary. By absorbing fluid (exudate) only in the bandage, one can minimize the effect of volume loss, and thus pressure loss, on the system. The materials that make up the bandage can be soft and compliant, and the chamber616includes more rigid components to reduce volume loss in the pump assembly so as to increase the likelihood that the pressure in the overall volume of the system stays in the therapeutic range. In view of the aforementioned, it is desirable to have the predefined chamber volume, i.e., V2, of the chambers516,616to be at least six times as large as the initial air volume portion, i.e., V1, (prior to the reactor consuming oxygen in this example) of the enclosed three-dimensional spaces102,202,302,302,502.

If desired, a pressure relief valve, similar to the pressure relief valve112, can be provided on the container body618to provide selective pneumatic communication between ambient and the chamber616. The expandable segment608can be compressed and retained by a retaining structure, which can be similar to the retaining structure212described above. Such a retaining structure can connect with the container body618and the expandable segment608and be removable therefrom to allow the expandable segment608to move from the compressed state to the expanded state. The expandable segment608can also cooperate with biasing element, and operate similarly to the biasing assembly described above with reference toFIG. 4.

For each of the embodiments discussed above, a thin top covering or coating can be applied on the outer surface of the body106,206,306,406,506to provide a soft to touch feeling for the user. For each embodiment, the body106,206,306,406,506and the expandable segments108,208,308,408,508can be made of a resilient material and can be connected or co-molded, cast, formed or printed with a soft pliable material to add flexibility and form to body contours.

Embodiments of negative pressure devices have been described above in particularity. Modifications and alterations will occur to those upon reading and understanding the preceding detailed description. Moreover, elements from one embodiment, e.g., the retaining structures212inFIG. 3, can be employed in other embodiments, e.g., used with the negative pressure device300shown inFIG. 4. The invention is not limited only to the embodiments described above. Instead, the invention is broadly defined by the appended claims and the equivalents thereof. It will be appreciated that various aspects of the above-disclosed embodiments and other features and functions, or alternatives or varieties thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.