Hyperbaric oxygen therapy is used to induce the growth of blood vessels in order to promote the growth of new skin tissue, close and heal ischemic wounds. However, systemic therapy also has its drawbacks. For example, hyperbaric oxygen may cause vasoconstriction, poisoning, and tissue destruction. When oxygen is supplied to the whole body, the central nervous system and lungs are at risk of poisoning. Topical hyperbaric oxygen therapy, on the other hand, avoids systemic toxicities, but is only applicable to open wounds, and has proven effective in healing refractory skin wounds. Since excess oxygen may be toxic to endothelial cells surrounding the wound, the consequences of local peroxytoxicity may cause a cessation of wound healing. Blockade of blood flow occurs and the formation of new blood vessels (neovasation) is stopped. However, any damage caused by a locally toxic dose of oxygen will generally heal after approximately two weeks of discontinuation of treatment.
Topical hyperbaric oxygen therapy requires direct supply of oxygen to open wounds. Oxygen dissolves in interstitial fluid and increases the oxygen content of the intercellular fluid (intercellular fluids). Such direct application of oxygen to the wound is advantageous. For example, because oxygen is supplied directly to the base of the ulcer, the oxygen pressure required to promote wound healing is much lower than that required for systemic oxygen therapy, which requires diffusion. Skin diseases that can be treated with topical hyperbaric oxygen therapy include osteomyelitis, burns and scalds, necrotizing fasciitis, pyoderma gangrenosum, refractory ulcers, diabetes mellitus ulcers and decubitus ulcers (decubitus ulcers). Cuts, abrasions and surgically created wounds or incisions may also benefit from topical oxygen therapy.
The prior art teaches the topical application of hyperbaric oxygen to place the affected whole limb of the patient in a sealed enclosure, such as one featuring controllable pressurized sealing and automatic regulation. The chamber supplies oxygen at high or normal pressure to the whole limb and not just to the wound. The disadvantage of such hyperbaric oxygen chambers for extremities is that they are expensive, difficult to sterilize and have the potential for cross-infection. To overcome these disadvantages, there is an opinion that a disposable polyethylene bag is required to replace the permanent oxygen tank. Although this approach would eliminate sterilization problems and reduce some of the cost, it still has its drawbacks. For example, an external source of oxygen must be provided. Even if the chamber is small, the compressed oxygen must be supplied from an external store of oxygen even at pressures as low as 1.04 atm. This requires the patient to be close to the oxygen cylinder during treatment. Furthermore, since the whole limb is placed in an oxygen tank or polyethylene bag, large areas of skin may be unnecessarily exposed to oxygen doses that may be toxic. The sealed arrangement of the oxygen tank or bag may also cause an undesirable tourniquet effect on the limb being treated.
The present invention seeks to provide an improved device and method for regulating hyperbaric oxygen enrichment supplied to skin wounds. The device is disposable, thereby eliminating the risk of cross-contamination. It also enables the patient to be unrestrained about a pressurized source of oxygen. Hyperbaric oxygen may be supplied directly to the local skin economically and conveniently without unnecessarily restricting the flow of blood to the treatment area. In addition, the device can reduce oxygen at the wound site, which can lead to cellular hypoxia. It has been found that an appropriate degree of hypoxia promotes capillary sprouting and proliferation. Starting from the tissue hypoxia, some new capillaries are formed accordingly (new blood vessels are generated). The increased blood flow, which increases the oxygen concentration in the tissue, promotes the complex healing process of wound closure. Thus, by increasing or decreasing (i.e. regulating) the supply of oxygen, one can promote the healing of the wound in a very advantageous manner.
Brief description of the invention
The present invention is directed to devices and methods for providing regulated hyperbaric oxygen for topical treatment of skin wounds. The device comprises a wound patch or bandage suitable for use on an oxygen treatable skin wound. The device is also equipped with an oxygen regulator or oxygen concentrator that generates oxygen according to an electrochemical process and supplies the oxygen to the skin wound.
The method of treating wounds with hyperbaric oxygen according to the invention entails covering the skin wound with an oxygen-generating bandage. The ambient air is brought into contact with a breathable cathode contained in a bandage. The oxygen present in air is reduced to negatively charged ions, i.e., superoxide (superoxide) and peroxide (peroxide), and their various unprotonated, protonated neutral states (HO)2、HO2-、O22-) Or hydroxide ions or H which does not dissociate at the cathode in accordance with a one-, two-or four-electron process2O2. One or more of the products then diffuses through the electrolyte and oxidizes at the anode, generating a high concentration (about 100%) of oxygen. Oxygen flows from the anode to the skin wound. An oxygen-rich environment is maintained at high pressure during the treatment.
This electrochemical process is driven by an internal or external power source. Reversing the polarity of the power supply reverses the process so that very low concentrations of oxygen (as low as around 0%) are provided to the wound, thereby regulating the oxygen concentration at the wound treatment site. Modulating the oxygen concentration controls the rate of wound healing by increasing or decreasing the oxygen concentration in the tissue that promotes wound healing.
An advantage of the present invention is that concentrated oxygen can be provided locally to a skin wound without the risk of providing toxic amounts of oxygen to the wound or to sites surrounding the wound. Avoiding the toxic effect of systemic administration.
Another advantage of the present invention is that the bandage or wound patch itself is portable and produces hyperbaric oxygen from the surrounding air to supply the patient without the need for externally supplied pressurized oxygen.
Another advantage is that the bandage completely closes the wound around the wound site. A fully closed wound may prevent infection by aerobic bacteria after anaerobic bacteria are killed by oxygen therapy. Further disinfection can also be effected chemically (e.g. by trace peroxides generated by electricity) as well as electrochemically within the bandage by electrochemical destruction at the electrodes.
Another advantage of the present invention is that the bandage provides an economical and convenient means for supplying hyperbaric oxygen to a skin wound. The oxygen bandage may be applied under a variety of pressures, for example from 0.5 to 5atm but more preferably from 0.75 to 2.5atm and most preferably from 0.95 to 1.1 atm. The actual pressure or applied pressure will depend on such variables as the desired oxygen concentration, the type of wound being healed, the duration and the comfort level of the patient. For example, for shorter durations, relatively low or high pressures may be more desirable than moderate pressures.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.
Detailed description of the preferred embodiments
The description which is now made with reference to the accompanying drawings, which are included to illustrate the preferred embodiments of the present invention and are not intended to limit the same, illustrate a novel and general method for generating hyperbaric oxygen for healing skin wounds. Turning first to fig. 1, a schematic diagram is a side view of the device or wound patch of the present invention. Molecular oxygen is electrochemically generated by means of a three-layer sandwich structure comprising a gas-permeable cathode 10, a separator membrane 14 in which a non-flowing electrolyte is embedded, and a gas-permeable anode 18. The cathode is exposed to the atmosphere and is intended to expose the anode to the skin wound. The electrolyte may be either alkaline or acidic, such as a proton conducting solid polymer electrolyte membrane, which is wetted or treated with an acid solution.
The apparatus shown in fig. 1 is used in substantially the same manner as the apparatus of patent 5,338,412 incorporated herein by reference. In this patent, molecular oxygen supplied by air is reduced to hydrogen peroxide ions, which move through a thin layer of electrolyte. These ions are oxidized at the anode to provide concentrated oxygen. The wound patch or bandage described herein maintains a very broad range of oxygen concentration processes. The atmospheric molecular oxygen supplied at 22 is reduced to negatively charged ions, i.e., superoxide and peroxide, and their various non-protonated and protonated states (HO) at the gas-permeable cathode 102、HO2-、O22-) Or hydroxide ions, or H which does not dissociate in accordance with a one-, two-or four-electron process2O2. Such cathodes are of the type used in fuel cells. One or more of the products then moves through the thin separator/electrolyte structure or membrane 14 to a gas permeable anode 18 where they are converted back to molecular oxygen. Molecular oxygen flows from the anode to the cathode 24 and is intended to flow to the skin wound.
The wound patch shown in fig. 1 is powered by an air-driven battery, in this case a zinc/air battery, of the same composition as used for conventional hearing aid batteries, and is based on this three-layer structure. In order to make the manufacturing simple, the advantage of the bipolar type is taken in design. As noted, a small amount of zinc powder is typically mixed with the gelled alkaline electrolyte and placed on top of the gas-fed cathode as the zinc electrode 28. It is then completely covered with a separator or film 32. To construct the cell, the gas-fed anode 18 is folded around the structure and placed directly on top of the separator to construct the cell's cathode 36. In other words, one gas permeable electrode serves two functions. Which is both the anode 18 that generates oxygen at 24 and the cathode 36 or air electrode in a zinc/air cell device. During use, air flows to the zinc/air cell as shown, for example, at 38.
As shown in fig. 1, an electrically insulating material 40 is placed around cathode 10, membrane 14, membrane 32 and cathode 36 to properly isolate the bandage from each of the active components of the cell, both electrically and ionically. The adhesive material shown at 44 is used to secure the patch to the skin wound so that oxygen cannot rapidly exit the treatment area. The wound is fitted with some one-way valves or small capillary holes to allow air to escape. Although the bandages are peripherally closed and provide antimicrobial protection in the absence of antibiotics or antiseptics, they can be used to increase protection.
The oxygen-generating bandage itself may be multilayered to make the patient more comfortable and to promote healing. The bandage includes, but is not limited to, layers of cotton gauze, polyoxyethylene-water polymer, and layers of topical ointments and other medications including antibiotics, antiseptics, growth factors (grawth factors) and living cells (living cells). The additional layers may include a battery, a sensor, and/or an oxygen concentrator. There is no ordering that must be followed for the layers, nor is there any requirement for operating means for all the layers.
The device shown in fig. 1 has several advantages. For example, the amount of zinc can be controlled in order to produce a certain amount of molecular oxygen. In this way, the possibility of oxygen overdose (it has been found that oxygen overdoses have a detrimental biological effect which leads to a cessation of healing) can be completely avoided, for example, by the patient not removing the wound patch after the treatment has ended. The air electrode and the zinc/air cell as a whole can be sealed during manufacture and activated just prior to use by exposing the oxygen cathode 10 to air.
Referring now to fig. 2, a single wound patch 48 may be equipped with several sealed zinc/air cells 50. This often allows the patient to use oxygen intermittently, as is the case with current therapies. Each battery may be manufactured according to a predetermined life span. For example, the service life of each battery may be set to 1, 2, 4h, longer or shorter. Batteries of different sizes may be attached to a wound patch so that they remain in place for a period of time before the patch is removed to clean the wound. This allows for different time periods of oxygen dosing to the wound. For example, treatment may be for 1 hour on day one, followed by 2 hours on day 2, and so on. Each cell section includes a peelable adhesive seal upon which the zinc/air cell or other air-driven cell is exposed to air and begins to operate. And 54 shows a portion where oxygen is generated.
For oxygen therapy treatments of 7 days or longer, a single battery with an electronic timing device may be used instead of multiple batteries. Longer treatments are also within the scope of the invention; however, that is not practical because the wound patch must be removed periodically to clean the wound. Since the wound patch is of a one-piece construction, it can in principle be made in any size or shape, even including a transparent plastic window immediately above the wound, so that the progress of healing (formation of new blood vessels) can be visually monitored without removing the patch. Fig. 2 shows such a viewing window or inspection window at 58. In use, the wound is positioned beneath the viewing window. As shown in fig. 1, the wound patch may be secured to the skin by a peripheral conventional adhesive layer 44. The wound patch may be formed into a variety of shapes, such as gloves, socks, sleeves, etc., or it may be cut to the desired size.
Fig. 2 shows another embodiment including a plastic frame 62. The frame is placed around an oxygen producing bandage 66. The plastic frame includes an adhesive along its edge 70 that secures the frame to the skin. An oxygen-generating bandage is supported by the frame. The adhesive along the edge 70 provides a seal against the escape of oxygen. The bandage can thus be removed without damaging the patient's skin. Increasing the comfort of the patient. The plastic frame may contain or define openings that act as a one-way pressure relief or release valve for release of gas. These valves or fine capillary holes prevent accidental overpressures which could cause possible bursting of the device. These valves or fine capillaries also eliminate air from the wound cavity when concentrated molecular oxygen begins to accumulate.
When using the wound patch with zinc/air cell device shown in fig. 1 and 2, it can be demonstrated by Faraday's law that 65.4g zinc produces 22.41 molecules of oxygen at 1atm pressure and room temperature.
In the case of wound patches, a small range of one-way valves or design with many small capillary openings is used to allow gas to flow from the anode compartment to prevent pressure build-up. After treatment, the flow of ambient air through the wound patch is immediately stopped to restore normal ambient air conditions to the wound site and prevent toxic excessive exposure of the new blood vessels to the air.
The wound patch shown in fig. 1 and 2 depicts a bandage for generating or regulating oxygen. The bandage includes an electrochemical device contained therein that generates oxygen according to a one, two or four electron process. The reaction is driven by an aerodynamic battery. The bandage and the associated electrochemical accessory shown in the figures demonstrate a preferred use scenario.
The generation and/or reduction of oxygen may occur with different electrochemical reactions. In addition to the two-electron processes already described, the reaction can be carried out at various temperatures on the basis of one-or four-electron processes or a combination of one-, two-and/or four-electron processes. As already mentioned, the two-electron process involves converting oxygen in the air intake to peroxide ions and/or H at the cathode2O2Allowing peroxide ions and/or H2O2Passing peroxide ions and/or H through the electrolyte and over the anode2O2Is converted to oxygen. An electronic process involves converting incoming oxygen to superoxide ion or its protonated form, passing the superoxide ion or its protonated form through an electrolyte, and converting the superoxide ion or its protonated form to oxygen at the anode. One method of requiring more energy involves reducing the feed rateOxygen contained in the gas and/or hydrogen (H) gas produced by a four-electron process2). This includes electrolysis of water. Generating hydroxide ions and/or (H) during electrolysis2) An electrode, designated 18 in figure 1, oxidizes water to produce molecular oxygen by a four electron process. This approach requires a catalyst in 1 or 2 electrodes to overcome the kinetic irreversibility of the reaction. It is expected that the amount of hydrogen generated under the conditions of actual use is small and thus does not cause any harm.
In the event that it is desired to provide concentrated oxygen to the wound site, the anode is directed toward the wound. To create an oxygen-deficient atmosphere within the treatment area, the polarity of the wound patch power supply is reversed to reduce oxygen on the electrodes in contact with the treatment area. Thereafter, the electrode functions as a cathode and oxygen is generated on the electrode-anode in contact with the surrounding atmosphere. Oxygen is provided to the skin wound at different pressures above or below atmospheric pressure. When the opposite polarity is desired, a power source may be required rather than a built-in bipolar battery.
Reactions that drive the regulation of oxygen (i.e., the production and/or consumption of oxygen) in various ways are all included within the scope of the present invention. The power for the oxygen concentrator may be supplied from another source separate from the wound patch. A single power control mechanism may include or include electronic timing, primary and secondary batteries, capacitors, Supercapacitors (Supercapacitors), photovoltaic cells, converters connected to alternating current (a.c.) power, and the aforementioned built-in bipolar batteries. These power sources may be placed in appropriate locations within or outside of the bandage/wound patch.
Although non-electrochemical methods may also be used to regulate the oxygen content of the treatment area, electrochemical methods are actually preferred as the method of generating and reducing oxygen. For example, chemically or thermally initiated reactions may be employed, which release or absorb oxygen in a controlled manner. These methods may also include inexpensive sensors and control circuitry for oxygen concentration, humidity, pressure and other conditions to monitor and control certain parameters (i.e., current density) and promote optimal healing.
The invention has been described with reference to the preferred embodiments. Modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the present application cover all such modifications and variations as come within the scope of the appended claims or the equivalents thereof.