Surgery: splint – brace – or bandage – Bandage structure – Skin laceration or wound cover
Reexamination Certificate
2001-01-29
2002-06-18
Lewis, Kim M. (Department: 3761)
Surgery: splint, brace, or bandage
Bandage structure
Skin laceration or wound cover
C602S002000, C602S054000, C607S096000, C607S108000
Reexamination Certificate
active
06407307
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a wound covering for wound treatment and, in particular, wound covers having a portion of the wound cover in non-contact with the wound and capable of delivering heat to the wound The wound covering preferably controls the temperature, humidity and other aspects of the environment at the wound site.
BACKGROUND OF THE INVENTION
Wounds in general, as used in this context, are breaks in the integrity of the skin of a patient. Wounds may occur by several different mechanisms. One such mechanism is through mechanical traumatic means such as cuts, tears, and abrasions. There are many instruments of causality for mechanical wounds, including a kitchen bread knife, broken glass, gravel on the street, or a surgeon's scalpel. A different mechanism cause for mechanical wounds is the variable combination of heat and pressure, when the heat alone is insufficient to cause an outright burn. Such wounds that result are collectively referred to as pressure sores, decubitus ulcers, or bed sores, and reflect a mechanical injury that is more chronic in nature.
Another type of mechanism causing a wound is vascular in origin, either arterial or venous. The blood flow to the affected region is altered sufficiently to cause secondary weakening of the tissues which eventually disrupt, forming a wound. In the case of arterial causes, the primary difficulty is getting oxygenated blood to the affected area. For venous causes, the primary difficulty is fluid congestion to the affected area which backs up, decreasing the now of oxygenated blood. Because these wounds represent the skin manifestation of other underlying chronic disease processes, for example, atherosclerotic vascular disease, congestive heart failure, and diabetes, these vascular injuries also are chronic in nature, forming wounds with ulcerated bases.
Traditional wound coverings, such as badges, are used to mechanically cover and assist in closing wounds. Such bandages typically cover the wound in direct contact with the wound. This may be acceptable for acute, non-infected traumatic wounds, but it must be kept in mind that direct bandage contact with a wound can interfere with the healing process. This interference is particularly prevalent for chronic ulcerated wounds because of the repeated mechanical impact and interaction of the bandage with the fragile, pressure sensitive tissues within the wound.
The benefits of application of heat to a wound are known, and documented benefits include: increased cutaneous and subcutaneous blood flow; increased oxygen partial pressure at the wound site; and increased immune system functions, both humoral and cell mediated, including increased migration of white blood cells and fibroblasts to the site.
However, heat therapy for the treatment of wounds, either infected or clean, has been difficult to achieve in practice. For instance, heating lamps have been used, but these resulted in drying of wounds, and in some cases, even burning tissue from the high heat. Due to these and other difficulties, and since most acute wounds usually heal over time, physicians no longer consider the application of heat to the wound as part of the treatment process. The thinking among medical personnel is that any interference in a natural process should be minimized until it is probable that the natural process is going to fail. Additionally, the availability of antibiotics for use in association with infected wounds has taken precedence over other therapies for the treatment of chronic wounds and topical infections.
In French patent number 1,527,887 issued Apr. 29, 1968 to Veilhan there is disclosed a covering with a rigid oval dome, its edge resting directly on the patient's skin. One aspect of the Veilhan wound protector is a single oval heating element resting on the outer surface of the rigid dome, positioned at the periphery of the rigid dome. Veilhan does not discuss the heating aspect other than to state that it is a component.
The benefits of controlling other environmental parameters around the wound site are not as well known. Controlling the humidity at the wound site and the benefits of isolating the wound have not been extensively studied and documented.
While the benefit of applying heat to wounds is generally known, the manner of how that heat should be used or applied is not known. Historically, heat was applied at higher temperatures with the goal of making the wound hyperthermic. These higher temperatures often resulted in increasing tissue damage rather than their intended purpose of wound therapy and healing. There is a need for appropriate wound care management incorporating a heating regimen that is conducive to wound healing, yet safe and cost effective.
SUMMARY OF THE INVENTION
The present invention disclosed herein approaches the treatment of wounds with heat based on an understanding of physiology. The normal core temperature of the human body, defined herein for purposes of this disclosure, is 37° C.±1° C. (36°-38° C.), which represents the normal range of core temperatures for the human population. For purposes of discussion and this disclosure, normal core temperature is the same as normothermia. Depending on the environmental ambient temperature, insulative clothing and location on the body, skin temperature typically ranges between about 32° C. and about 37° C. From a physiologic point of view, a 32° C. skin temperature of the healthy distal leg is moderate hypothermia. The skin of the distal leg of a patient with vascular insufficiency may be as low as 25° C. under normal conditions, which is severe hypothermia.
A fundamental physiologic premise is that all cellular physiologic functions, biochemical and enzymatic reactions in the human body are optimal at normal body core temperature. The importance of this premise is seen in how tightly core temperature is regulated. Normal thermoregulatory responses occur when the core temperature changes as little as ±0.1° C. However, the skin, as noted above, is usually hypothermic to varying degrees. For example, the skin of the torso is usually only slightly hypothermic, whereas the skin of the lower legs is always hypothermic. Consequently, wounds and ulcers of the skin, regardless of location, are usually hypothermic. This skin hypothermia slows cellular functions and biochemical reactions, inhibiting wound healing.
The effects of hypothermia on healing are well known. A number of regulatory systems within a human are affected, such as the immune system and coagulation, with both platelet function as well as the clotting cascade affected. Patients with hypothermic wounds experience more infections which are more difficult to treat, have increased bleeding times and have been shown to require more transfusions of blood. All of these complications increase morbidity and the cost of patient care and, to a lesser extent, increase the likelihood of mortality.
One purpose of the present invention is to raise the wound tissue and/or periwound tissue temperatures toward normothermia to promote a more optimal healing environment. The present invention is not a “heating therapy”, per se, where it is the intent of “heating therapy” to heat the tissue above normothermia to hyperthermia levels. Rather, the present invention is intended to bring the wound and periwound tissues toward normothermia without exceeding normothermia.
The medical copy has not historically considered normothermic heating to be therapeutic. Many physicians feel that hypothermia is protective and, therefore, desirable. Studies with the present invention would indicate that this widely held belief that hypothermia is at least benign or possibly beneficial is incorrect with regard to wound healing.
The present invention is a wound covering for application to a selected treatment area of a patient's body that includes, at least as a portion of the selected treatment area, a selected wound area. The selected treatment area may also include a portion of the area immediately proximate to the wound area referred to
Augustine Medical, Inc.
Gray Cary Ware & Freidenrich
Lewis Kim M.
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