Abstract:
A negative pressure wound therapy (NPWT) dressing includes a wick configured for placement over an incision. A transfer assembly includes a compressible, porous core with a permeable cover placed over the core. The transfer assembly is positioned on the wick in fluidic contact and is covered by a dressing cover, which is configured for adhesive attachment to the patient around the incision. A drain slip including a proximal end configured for placement in the incision extends through the wick and the transfer assembly and is configured for connection to a negative pressure source. A NPWT method includes steps of draining a closed incision using negative pressure applied to a drain slip.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority in U.S. Provisional Patent Application Ser. No. 61/800,224, filed on Mar. 15, 2013, which is incorporated herein by reference. The following patents and published patent applications are related and are also incorporated herein by reference: U.S. Pat. No. 6,951,553, issued on Oct. 4, 2005; U.S. Pat. No. 6,936,037, issued on Aug. 30, 2005; U.S. Pat. No. 7,976,519, issued on Jul. 12, 2011; U.S. Publication No. 2011/0270201, published on Nov. 3, 2011, for U.S. patent application Ser. No. 13/181,399, filed on Jul. 12, 2011, U.S. patent application Ser. No. 13/245,677, filed on Sep. 26, 2011, and U.S. Provisional Patent Application Ser. No. 61/725,412, filed on Nov. 12, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to negative pressure wound therapy (NPWT) and in particular to dressings for surgical incisions. 
         [0004]    2. Description of the Related Art 
         [0005]    Current external or topical vacuum-assisted dressings (also referred to as negative pressure wound therapy (NPWT) systems (e.g., post-surgical, incisional dressing systems)) have been shown to quickly (e.g., possibly within a few hours) seal and close the dermal-epidermal portion of the skin incision (side-to-side). This has the consequence (clearly evident in several clinical studies now) of preventing surface bacteria from entering the incisional space or the wound below and thus preventing incisional or surgical wound infection, particularly superficial infection. 
         [0006]    An area of investigation relates to the “deep” sub-dermal effects of topical vacuum-press systems and treatment procedures. For example, an investigational topic relates to the prevention or reduction of the effects of seroma and hematoma. Another area of investigation concerns how far sub-dermal or deep in the incision/surgical wound is there an effect of the dressing on the surface. 
         [0007]    Previous systems have used rayon-wrapped Granufoam dressing material (Kinetic Concepts, Inc. of San Antonio, Tex.) and NPWT techniques on the skin surface with a liner, routinely accompanied by large dissection space procedures with deep “Hemovac-type” drains brought out through separate stab wounds peripheral to the incision. Differences in the behavior of these drains have been observed clinically compared to the drainage characteristics known to occur without the external vacuum-assisted dressing, indicating that post-incisional dressings effected outcomes. Without this vacuum-press type surface dressing, these Hemovac-type drains would have a significant measureable amount of drainage over the first few days, then decreasing to what is considered an “irritation” level of drainage (10-20 cc&#39;s of clear yellow serum—i.e., no bleeding, just the amount of reactive drainage associated with the simple presence of this plastic tube in the tissue preventing complete apposition of the tissue by its presence). 
         [0008]    The concept is that this amount of drainage would continue day after day as long as the tube was in place. But with a NPWT type of dressing in place, drainage during the first few post-incision days can be significantly decreased—essentially to irritation levels. In fact, oozing into the drain, after closure of the incision, has sometimes been observed to suddenly stop after the foam dressing is compressed with the drains placed deeply, e.g., at fascia level. So it was felt that deep bleeding ceased when the vacuum-press dressing was compressed using NPWT procedures. These observations suggest that vacuum-press post-operative dressings decrease hematoma and seroma formation. 
         [0009]    As an incision is being closed, tissue voids, pockets, spaces and irregularities may prevent firm tissue-to-tissue apposition and create an actual “space.” This is quickly filled by fluid—depending on the circumstances, this fluid consists of a spectrum from pure blood to pure extracellular and lymph fluid without any blood or serum clotting factors. The initial behavior of this fluid collection depends on which side of the spectrum it is. If there is enough pure blood to clot, this will be a hematoma. The consequence of any “space-occupying” hematoma is that the process of clot lysis, which proceeds over several days, carries with it the risk of “unclotting” blood vessels of sufficient size and pressure such that rebleeding occurs and causes a post-operative complication of an “expanding hematoma.” 
         [0010]    If re-bleeding does not occur, problems can occur with probable expansion at both ends of this spectrum of fluid in a space. Lysis, cell and clot breakdown with the freeing of protein can all produce particles that create an osmotic pressure. If this is greater than the absorptive capability, the fluid expands rather than contracts. If that occurs early before there is any collagen production with strength, then this breaks apart the surrounding tissue apposition (aided by any irregular tension from the suture position, necrosis from just the presence and nature of the suture ligatures, cautery debris, surface of the incision trauma from the very act of surgery, etc.). In other words, one can think of the dissection space of an operation as easier to be again split apart than to be held together. 
         [0011]    So, even in a pure seroma that never had any blood in it to start with, there is still enough oncotic pressure from the unabsorbed large proteins such that expansion becomes a greater force than absorption and that, plus the simple mechanics of the presence of liquid between layers preventing collagen bridging and development of any strength between opposing layers of tissue, allows us to see that seromas also “expand” and we can see how just their very presence is a potentiating factor for “dehiscence.” 
         [0012]    If we look at the above scenarios, we get another glimpse at what NPWT-Incisional Dressings or topical vacuum pack dressings systems seem to be doing: they are changing the healing process during the critical first  48  hours of wound healing. Because the dressing enhances and enables tissue apposition, not only at the surface but also at levels beneath the dressing, it reduces and prevents the early increase in size of liquid-filled space lesions in incisions. But a review of the current data suggests that it does not take away a space-occupying fluid collection that is already there on completion of the closure before a NPWT-incisional dressing is applied on the operating table. Use of a buried suction drain such as a Hemovac drain should reduce this. But looking at these dynamics in this way suggests another alternative. 
         [0013]    If we look at methods to decrease the presence of liquid-filled space-occupying lesions (i.e. hematoma/seroma) at the moment the incision is compressed on the operating table, we see an alternative to Hemovac drains brought out through a separate stab wound and left for several days, and to the option of preventing complete sealing of the incision by placing Swanson-type or wick drains through the incision, at its end or between sutures and leaving them for 24 to 72 hours to allow the incision to drain, and then having to change the entire topical vacuum-pack system, and that alternative is to drain the hematoma/seroma collections that form during closure on the operating table just before or, preferably, just after the foam core in the external dressing is compressed and then remove the drain and seal the dressing before the patient leaves the operating MOM. 
         [0014]    Again, this entire concept can be summarized by the idea of the “set” of the wound or incision. Orthopedic surgeons reduce and hold fractures in position as the plaster cast is applied. Plastic surgeons roll and “milk” wounds to get everything drained and in a suspended new position before the wrap or tape or garment is applied to hold this “set.” General surgeons use “retention” sutures and large ligatures to hold at-risk abdominal incision closures in place. 
         [0015]    External vacuum-assisted NPWT systems use dressings that are eminently suited to hold the tissues in set apposition. The task then is to formalize the final removal of still-present drainage and to arrange the set of the wound as the foam core compresses. This disclosure then is to propose alternative methods and materials to accomplish that for both the peel-and-place and the customizable NPWT systems. 
       SUMMARY OF THE INVENTION 
       [0016]    In the practice of the present invention, topical, NPWT surgical incisional systems and methods are provided, which can include surgical adjuncts, hybrids and composites. Wound therapy can be utilized with these systems and methods for facilitating wound healing and reducing potential complications. 
         [0017]    Other objects and advantages of the present invention will be apparent from the following description. Detailed descriptions of exemplary embodiments are provided in the following sections. However, the invention is not limited to such embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The drawings constitute a part of this specification and include exemplary embodiments of the present invention illustrating various objects and features thereof. 
           [0019]      FIG. 1  is an exploded diagram of a NPWT system applied to an incision. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     I. Introduction and Environment 
       [0020]    As required, detailed aspects of the present invention are disclosed herein; however, it is to be understood that the disclosed aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0021]    Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, up, down, front, back, right and left refer to the invention as orientated in the view being referred to. The terms “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the aspect being described and designated parts thereof. Forwardly and rearwardly are generally in reference to the direction of travel, if appropriate. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning 
       II. Embodiment 1—Percutaneous Drain Slip Peripheral to the Incision and to the NPWT System Can Be Placed “Outside” the Drape 
       [0022]    A NPWT system  2  is shown in  FIG. 1  and includes percutaneous drain slips  4 , which can extend into an incision  6  and terminate exteriorly at a film cover or drape  8 . The slip drain  4  material can be any type of fluid impermeable thin plastic or rubber of small caliber (only a few millimeters in width) that will slide easily in the tissues and be of sufficient tensile strength that it will not tear or break as it is removed. Silicone wicks of the Swanson Drain variety are an example. They can be provided in the dressing kits or as a separate package in a roll or coil of 100 cms. This should be sufficient to run the entire length of the incision or cut into sections and run half the incision length—past either end or out the sides. 
         [0023]    The slip drains  4  can be placed in the incision  6  and extend towards opposite ends and can exit the incision at an approximate midpoint and extend upwardly through appropriate openings or slits  12 ,  16  in a wick  10  and a mat  14 . The slip drains  4  can extend further outwardly between the recoil transfer assembly halves  18  and terminate under the film cover or drape  8 , or externally to the dressing  2 . The recoil transfer assembly halves  18  can include open-cell (e.g., polyurethane) foam or sponge material cores  20  with fluid-permeable (e.g., membrane or fabric) covers  22 . 
         [0024]    An exterior connector bridge  24  is attached on the exterior of the drape  8  and can be used to cover a gap between drape sections. The dressing system  2  can thus be customized to various lengths and configurations. Fluid inlets  26  can be located in the sides of the dressing assembly  2  and fluid outlets comprising elbow-configuration fittings  28  can be placed on the top of the dressing system  2 . Various fluid inlet and outlet configurations and placements can be utilized. 
         [0025]    Alternative slip drain configurations could be utilized with different numbers of slip drains, wound interfaces and dressing exits. Moreover, various types of drain devices could be utilized and connected to external devices, including other dressings, as indicated for a particular incision or treatment procedure. 
         [0026]    The technique would be to lay this strip at fascial level after its closure or in the depths of the wound or in specific planes that the surgeon feels are at risk for seroma/hematoma collection. The drain is brought from the inside to the outside through a percutaneous stab wound using a long narrow clamp from the inside and incising a tiny stab wound over the clamp tip holding it at skin level, re-grasping the drain from the outside and then pulling it through till it is flat or straight in the incision bed. Skin closure is completed and the external dressing with foam core and liner is applied and vacuum instituted. The wound is then massaged and manipulated side to side to insure all deep layers are in good apposition. The incision, over the NPWT-incisional dressing is then rolled from the point(s) furthest away from the percutaneous drain site toward it. The egress and collection of this drainage is enhanced by using the ubiquitously available operative suction at the percutaneous stab wound with a 4×4 gauze sponge over the drain (and under it if desired). The suction picks up the drainage as it egresses and enhances its migration outward. After the rolling (or even simple manual milking), the suction is kept in place over the 4×4 as the drain is pulled out beneath it. The skin stab wound is then sealed with a simple steri-strip or small piece of paper tape over it. The patient is then allowed to emerge from anesthesia and taken to recovery and the incisional NPWT continued as usual. 
       III. Embodiment 2—Drain Slip Brought Out Through the Incision or Percutaneously but Still “Inside” and Under the Drape and/or the Foam and Mat of the Dressing 
       [0027]    In this embodiment, the materials provided in the “drain” kit include the above described 100 cm roll of silicone slip drain (sizes and material specifics are NOT limiting) but also a convenient size of a covering wicking fabric (e.g. 3 or 4 pieces of rayon about ½ inch wide by 4 inches in length) and sealing strips (3 or 4 pieces of hydrocolloid about 8-10 mm&#39;s wide—such as are available in the new customized Prevena NPWT kit from Kinetic Concepts, Inc. to allow edge sealing) and strips of sealing drape. 
         [0028]    The method is similar to that described in the first embodiment except that after laying the slip drain along the fascia, it is brought up to the surface at the end or edge of the incision (can theoretically be any point judged optimal by the surgeon to evacuate potential deep space collections of drainage). Closure is completed and the drain, from the incision to a point beyond where the drape will end, is covered with the protective wicking strips (e.g. rayon). The vacuum is then applied to the external dressing, the foam core compressed and the rolling/milking and drainage evacuating procedure described above is carried out, again protecting and enhancing the evacuation point with a 4×4 gauze sponge and using the operating-room suction. The drain slip is aided in its removal under the drape by the presence of the intervening wick material which is left in place and the edge, where the drain was removed, of the wicking material beyond the drape is trimmed and the potentially open leak point of the wicking material exit site is sealed by applying a hydrocolloid strip and additional drape over this point. 
         [0029]    An adjunctive maneuver that may aid the application of compression to the external dressing foam over the incision before the drain is extracted (as described above), now that we have, as it were, a built-in significant leak where we&#39;ve run the drain slip under the drape, is to use the operative suction to draw down the foam (avoiding exhausting the battery life of the small vacuum pump), digitally pressing down on the drain-slip area to decrease the leak, and then clamping the tubing to the attachment patch on the dressing (rubber-shod clamp or similar method). The operative suction is then available to place on the drain exit point and proceed as described above. After the drain is removed and the edge sealed, the vacuum pump can be applied to the tubing and the procedure is completed. Of course, this step is not necessary if there are two suction sources in the OR or if one source is split with a Y-tube. So these are additional options. 
         [0030]    It should be understood that there are many varieties and alternatives of applying these principles of draining the fluid and achieving the “set” of the operative wound—before or after the vacuum pack system is applied or compressed. The classic Swanson drain technique is to close the incision first and then use long, thin forceps to inset the drain slip between the sutures. Doing this, we can see that one option is even to just cover the drain slips with 4×4 gauzes or a lap tape and manually form and mold and compress the wound to get the residual drainage out and the remove the slips and apply the external vacuum dressing. The drain slips can be brought out at any area of the incision or, as described above, percutaneously beyond the incision. These maneuvers reduce the risk of spaces where tissue is not apposed, which will subsequently become seromas and hematomas. Because of this reduced risk, the need for a Hemovac-type drain is reduced. 
         [0031]    It is to be understood that the invention can be embodied in various forms, and is not to be limited to the examples discussed above. The range of components and configurations which can be utilized in the practice of the present invention is virtually unlimited.