Externally-applied patient interface system and method

Abstract

A surface-wound healing dressing for a wound or incision includes a slip drain located within the closed wound or incision. A wick is placed over the closed wound or incision in contact with the slip drain. A mat is placed over the wick and adapted for fluidic communication therewith. A recoil core includes a foam material and is adapted for placement on the mat. A wound healing method includes the steps of placing a slip drain, placing a wick over the slip drain, placing a recoil core over the wick and covering the recoil core with an overdrape. The overdrape is adapted for connection to an external negative pressure source, such as a vacuum.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to externally-applied wound dressings and wound closure methods.

2. Description of the Related Art

Wound-dressing and wound-healing include what is known as “moist wound healing.” Three major components that constitute the external and physical environment of the healing wound should, in an ideal wound-healing environment, be controlled. First, wound healing is inversely related to bacterial growth. Second, it has been shown that, holding other variables constant, there is a clear linear relationship between the moisture level at the wound-site and the rate of epithelial advancement. The final important characteristic is the surface contact property of the wound dressing. The surface contact property can help to control the other two major factors. The contact layer must be made of a suitable material that promotes endurance of the dressing as well as comfort to the patient.

Thin pieces of foam have been used in moist-wound healing applications. The external face of the thin foam was more open allowing for enough moisture retention initially, but then allowing drying to occur with the dressing still in place. The internal face (or tissue-contact face) had a compressed or less-open pore configuration. Because this foam did not adhere to the wound, it could be moved or removed without disrupting the epithelium. However, this practice was often limited to small incisions since the thin foam is incapable of managing a large amount of exudate from a large, fresh wound, and if exudate accumulates under the foam piece the foam will lose surface contact, which allows bacteria to build up. By preventing granulation ingrowth, the compressed surface allows epithelial migration to advance beneath the foam. However, this type of surface had even more problems staying in intimate contact with the surface, especially in the face of exudate.

In general, epithelium advances or migrates best if moisture is maximized and then matures best if moisture is minimized. Although the idea of moist wound healing is not new, the perfection and maximization of the use of this healing process is far from perfected.

Another important aspect of wound healing relates to the respective roles of the vascular and lymphatic circulatory systems, both of which are involved in wound healing, but perform different functions. An injury to tissue involves both vascular and lymphatic circulation. The vascular system clots due to the serum and platelets, which control bleeding. Lymph fluid, however, lacks comparable coagulating properties. Moreover, the smaller-channeled peripheral lymphatic system lacks the muscled walls of the vascular circulatory system or the more proximal large-channel lymphatics. Stemming the outpouring of lymph fluid from these smaller channels involves compressing the lymphatic circulatory system through surrounding tissue swelling from an accumulation of edema and interstitial fluid. Unlike the quick response of coagulating blood, lymphatic circulatory system closure tends to be slower and can take days.

Based on the involvement of the vascular and lymphatic circulatory systems in wound healing, influencing the performance of these circulatory systems can significantly improve wound healing. Wound closure can be achieved more quickly and infection risks can be reduced by controlling the factors affecting vascular and lymphatic circulation. For example, increased perfusion of blood flow in the wound site generally promotes healing and reepithelialization. Individual cells are also responsive to mechano-inductive forces, such as compression and tension. Properly applied and sequenced, compression and tension can promote healing.

The present invention addresses these wound healing factors by controlling and directing compression, tension and other physiological variables associated with the tissues and the fluids associated with the wound site and otherwise involved in the wound healing process.

SUMMARY OF THE INVENTION

In the embodiments of the invention described in more detail below, the unique dressing and method accomplish the objectives of enhancement and protection of (re)epithelialization, both migration and maturation, without disruption of the fragile layer by undue adherence or by motion/friction/abrasion and yet maintaining the closest of surface contacts without intervening dead space or its consequence of fluid accumulation, lytic bleeding, and micro abscess formation and lack ultimately of the ability to dry and mature epithelium. This is done by drawing away air and liquid from the wound and by introducing fresh air and/or fresh liquid to the wound to expedite healing. In this embodiment, air and moisture levels at the wound-site can be balanced by using vacuum pumps to remove excess air or moisture, and input pumps can be used to add additional dry air or moisture, or a gas or other elements which enhance healing. The vacuum pump will also provide the necessary vacuum press effect, keeping the dressing against the wound in intimate contact and enhancing healing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an external dressing system embodying an aspect of the present invention.

FIGS. 2-4 are cross-sections of the dressing system.

FIG. 5 is an isometric view of an alternative embodiment dressing system with sutures over a recoil core.

FIG. 6 is an exploded view of another alternative embodiment dressing system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. Preferred Embodiment External Dressing System 1102

FIG. 1 shows the preferred embodiment external wound dressing system. A wound 6, such as an incision, can be prepared by placing an external dressing 1102 onto the wound. The dressing 1102 promotes healing at three levels of the wound repair continuum: healing (epithelialization) of an open wound, stability of a recently epithelized, but not matured, wound, and maintenance of a mature or intact epithelium without breakdown under a dressing. This dressing device 1102 has the unique advantage that it can be applied for a short period of time (days) or left in place without changing for up to six weeks. This is possible because the wound removes old air and liquid from the wound-site and introduces fresh air and liquid to the wound-site to expedite the healing process.

The external dressing 1102 can be configured with various components, which can be selected and configured for expediting and optimizing the healing procedure for various closed wounds and patient conditions. By way of non-limiting example, the external dressing 1102 includes a surface contact layer or wick 1104 comprising a wicking material layer, a mat 1106, a polyurethane foam core 1108 with a lattice covering 1110 and a semi-permeable film cover 1112 overlying the other components.

An optional, perforated tubular deep drain (not shown) can be placed in or in proximity to the wound 6 and slip drains 1116 can optionally be placed in the wound 6. Suitable, optional closures for the wound 6 include sutures 1118, staples, adhesives, etc.

Alternatively, a suitable direct-contact foam core 1108 can be placed directly on the skin surface 42 and simply covered with the membrane film cover 1112. Still further, the foam core 1108 can be completely enclosed in a cover layer of a suitable material, such as a wicking material layer. Further still, the dressing 1102 can be completely unitary and self-contained for direct placement, whereupon the pressure differential feature described below can fix the dressing 1102 to the intact skin surface for proper positioning over the wound 6.

The core 1108 can be placed on top of an optional mat 1106, which can be selected to cooperate with the wicking material layer 1104 in conveying fluid from the wound 6. The core 1108 can distribute vacuum pressure differential to the surface contact layer 1104. The core 1108 is preferably collapsible and flexible and returns to its approximate original size and shape when vacuum pressure is removed. Without limitation, a suitable core material is an open-cell hydrophobic foam material which will maximize the above-listed desirable characteristics of the core 1108. This material can be integrated with the surface contact layer 1104. Other core materials may be used instead, such as hydrophilic foam, fiber matrix pads or a hybrid composite material comprising, e.g., beads and fibers.

The cover layer 1112 covers the other components including the compression core 1108 and the surface contact layer 1104. The cover layer 1112 is preferably relatively thin and flexible so that it can be collapsed over the underlying core 1108 to distribute the atmospheric pressure differential to all covered areas. Suitable, commercially-available, semi-permeable membrane materials are discussed above.

In an exemplary configuration, multiple top surface ports 1120a,b are provided on top of the cover layer 1112 and are connected to suitable fittings 1122 adapted for connecting to fluid-conveying tubing and conduits, which in turn connect to the equipment described below. Additional, perimeter ports 1124a,b are provided in the cover 1112 in proximity to the core perimeter and can be provided with tubular fittings 1126.

In operation the slip drains 1116 would adhere to the adhesive on the underside (contact surface) of the cover layer 1112 for extraction when the cover layer is removed, e.g., for a dressing change.

II. Closed-Wound Treatment Method with Dressing 1102

As shown in FIGS. 2-4, the dressing 1102 is generally adapted for use in a configuration providing internal compression and passive external resistance. More specifically and without limitation, the fluid forces and pressures generated and applied by the dressing 1102 can be described as follows:

• • 1) The dressing 1102 exerts a downward (compression) force against the contact surface 42 to which it is applied, i.e., generally around the incision 6. The skin 42 and the tissue immediately beneath it are subject to an outwardly-directed lifting force due to the negative pressure in the dressing 1102. These forces and pressures tend to cancel whereby the dressing 1102 is in a compressed, balanced, equilibrium condition.
  • 2) The dressing 1102 creates a pressure differential with respect to the surrounding ambient atmosphere and the dressing interior, exerting a compressive force corresponding to the ambient air pressure, which varies among different locations but tends to remain within certain well-known ambient air pressure ranges at given locations. The components within the dressing 1102 are compressed relative to each other.
  • 3) Based on the balance of forces acting on the dressing 1102 in a steady state, a relatively fixed but flexible dressing 1102 tends to be firmly attached, i.e., molded, to the skin surface 42 by the operation of the atmospheric pressure differential.
  • 4) The dressing 1102 converts the overlying intact skin 42 from an elastic layer to a relatively inelastic layer, which effectively resists pressure changes below the skin.
  • 5) Pressure changes below the skin surface 42 are provided by the following physiologic functions: a) arterial pulsation, which tends to be amplified by the inelastic characteristic of the dressing 1102 coupled and cooperating with the skin 42; b) muscle contraction, which also tends to be amplified by this inelastic characteristic of the system; and c) the leakage of tissue fluid and the buildup of edema, e.g., intracellular edema.

Edema fluid buildup is the means by which leaking lymphatics are closed by compression. As pressure increases in the tissue from the buildup of edema fluid, the lymphatic vessels tend to be compressed. The dressing 1102 facilitates the earlier compression by amplifying the effects of bleeding and edema fluid buildup. Thus, the normal lymphatic system compression response, which can take approximately 3 days, can be significantly accelerated to the point that the edema phase is almost eliminated. Bacteria which appear over the several days of the normal edema phase are cleaned up in the wound site by macrophages and white cells which are also released into the wound over the several days. By eliminating the edema phase this entire inflammatory phase can also be eliminated. By achieving early reepithelialization, wound healing can be actually accelerated and the wound protected from bacterial invasion by this technique. Epithelial cells begin to move and migrate to the wound site based on the lymphatic system control. The edema formation and inflammation phases of normal wound healing can thus be avoided or at least minimized.

III. Alternative Embodiment External Dressing System 1130

FIG. 5 shows an alternative embodiment external wound dressing 1130 with a core 1132, which can be encircled or otherwise in contact with sutures 1134, which are connected to the slip drains 1136.

IV. Alternative Embodiment External Dressing System 1140

FIG. 6 shows another alternative embodiment external wound dressing 1140 with a pair of cores 1142 positioned in end-to-end relation. A film bridge 1144 covers abutting ends of the cores 1142.

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.

Claims

1. A surface-wound healing dressing for a closed wound or incision, which dressing includes: a slip drain configured for placement within said closed wound or incision;a wick configured for placement over said closed wound or incision and in contact with said slip drain;a mat configured for placement over said wick and configured for fluidic communication therewith;an external fluid transfer component including a foam recoil core and configured for placement over said mat;an overdrape configured for placement over said external fluid transfer component in covering relation and configured for releasable attachment to a patient;wherein said dressing is configured for draining said closed wound or incision via said slip drain;wherein said recoil core is configured for compressing under negative pressure and recoiling to its original position when said pressure is removed;a negative pressure source configured for extracting fluid from said dressing;wherein said slip drain comprises a flat, flexible material;wherein said slip drain includes an internal portion configured for placement within said wound or incision and an external portion configured for placement externally thereto;wherein said slip drain external portion is configured for folding over a skin surface adjacent to said wound or incision; andwherein said slip drain external portion adheres to said overdrape for extraction when said overdrape is removed.

2. The dressing assembly according to claim 1, which includes: said overdrape having an opening to said external fluid transfer component; andsaid opening forming a discharge port for discharging fluid from said dressing assembly.

3. The dressing assembly according to claim 1, wherein said slip drain comprises a plurality of slip drains.

4. The dressing assembly according to claim 2, which includes: said external fluid transfer component including proximal and distal surfaces and a perimeter edge extending therebetween;said wick comprising a proximal wicking material layer engaging said external fluid transfer component proximal surface and configured for overlying said wound or incision; anda distal wicking material layer engaging said external fluid transfer component distal surface and said overdrape.

5. The dressing assembly according to claim 1, wherein said recoil core comprises a reticulated, compressible foam material chosen from among the group consisting of polyurethane ether (PUE) and polyvinyl acetate (PVA).

6. The dressing assembly according to claim 1, wherein said wick comprises rayon.

7. The dressing assembly according to claim 1, wherein said negative pressure source comprises a manually-operated vacuum-type device.

8. The dressing assembly according to claim 2, which includes: a wicking material cover enclosing said external fluid transfer component;said cover including a perimeter edge;said fluid transfer component having compressed and uncompressed configurations; andsaid wicking material edge buckling and forming a laterally-projecting rim with said fluid transfer component in its compressed configuration.

9. The dressing assembly according to claim 8, which includes: said recoil core forming an air-entrapment interior zone with the application of negative pressure thereto;said recoil core forming a fluid transfer zone at its outer surface and adjacent to said wicking material cover; andsaid fluid transfer zone being adapted for directing fluid from said wound or incision to said discharge port.

10. The dressing assembly according to claim 1, which includes: a sensor connected to said fluid transfer component and adapted for sensing a characteristic thereof and providing an output signal corresponding to said characteristic;a controller connected to said sensor and receiving input signals therefrom and providing an output signal to said pressure source; anda feedback loop connected to said controller output and to said controller for providing a feedback signal corresponding to said controller output and inputting same to said controller.