Surgery: splint – brace – or bandage – Bandage structure – Skin laceration or wound cover
Reexamination Certificate
2002-03-22
2003-09-02
Lucchesi, Nicholas D. (Department: 3764)
Surgery: splint, brace, or bandage
Bandage structure
Skin laceration or wound cover
C602S041000, C602S058000, C604S304000
Reexamination Certificate
active
06613953
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to wound treatment using an outer wound covering which both thermally insulates the wound and surrounding skin area to minimize heat loss and conducts heat from surrounding skin to the wound in order to maintain the wound close to normal body temperature.
BACKGROUND OF THE INVENTION
There are two types of common chronic wounds. One type termed a bed sore or pressure sore is caused by constant pressure applied to a part of a body when a patient has limited mobility in a hospital bed, wheel chair, etc. The pressure point reduces circulation to that part of the body resulting in lowering of temperatures (hypothermia), reduced physiological activity, and finally the breakdown of tissue at the pressure point causing a wound. A second type of chronic wound is caused by reduced vascular activity at the wound site which reduces the flow of oxygenated blood to the wound area (arterial) and or accumulation of body fluid at the wound site (venus). This second type of chronic wound has an underlying cause such as diabetes or artherosclerosis. Due to the lack of adequate blood circulation to the wound area, this area is typically at a lower temperature relative to healthy skin surrounding the wound. Healthy skin exhibits surface temperatures which are several degrees lower than the body core temperature of 37° C. due to heat loss to the environment. The temperature of the surface of a wound can be significantly lower than that of normal skin, sometimes approaching temperatures as low as the surrounding room air. The application of heat to a wound has been shown to increase blood flow to the wound thereby increasing oxygen concentration at the wound site, giving increased rates of fluid and waste removal from the wound and increased immune function.
The therapeutic application of heat to a wound has been common practice since ancient times. Various types of artificial heating have been used on wounds including such devices as hot water bottles, warming pads, and heating lamps. These kinds of therapies can result in the accidental burning of the wound or surrounding skin area or the excessive drying out of the wound. There has also been concern amongst medical practitioners that heating a wound above the core body temperature can result in accelerated growth of bacteria due to both the elevated temperature and the reduced capacity of a chronic wound to fight infection.
Heat loss from a wound is the result of heat transfer from the wound to the surrounding environment. Heat transfer can occur in three basic ways. The first type, conductive heat transfer, occurs when energy is transported from one body to another due to molecular vibration and interaction. An example of this kind of heat transfer is the hand touching a cold piece of metal where the molecules of the skin of the hand lose energy by inducing vibration in the atoms of the metal. The second kind of heat transfer is convection which is heat energy transport due to bulk fluid motion along the surface of a solid. An example is the “wind chill factor” where the motion of the air hitting the body removes additional heat and makes the outdoor temperature feel colder than it really is. Finally there is radiation heat transfer which results from the emission of electromagnetic waves from a surface. Heat eminating from a light bulb is an example of this kind of heat transfer. The third type of heat transfer is usually only significant at temperatures above 200 C. and is a minor component-of overall heat transfer at room temperature up to normal body temperature. The body, which maintains a constant core temperature, utilizes blood flow as a heat transfer medium similar to water in a car's radiator. As it flows, the blood heats the body's extremities such as the leg, foot, or arm. At the same time the skin of these extremities is constantly losing heat to the environment primarily due to conduction and convection heat transfer. Chronic wounds, having impaired blood flow, tend to lose heat to the environment without getting enough heat replenishment from the blood.
Minimizing heat loss from a wound is an alternative method to maintain an elevated wound temperature without resorting to external heating devices. Westby et al (U.S. Pat. No. 5,531,670, 1996) describes a heat conserving bandage consisting of one or more heat reflecting layers which reflect radiation heat eminating from the body back in the direction of the body. The bandage wraps around muscle and bone tissue and is used for heat therapy on muscles or other internal organs on both animals and humans. It is not intended for use on skin wounds, which due to their location on the exterior of the body tend to lose significantly more heat than internal organs such as muscle. All the examples of therapy using the Westby patent related to internal organs such as muscle, ligaments etc. According to the patentees, the primary mechanism for heat preservation is the reflection of radiation heat back to the source. As stated above, radiation heat transfer is small compared to the other two heat transfer mechanisms for temperatures below 200° C. The patentees also mention the use of closed cell rubber as a thermal conduction insulator. There are much better barriers to conduction heat transfer available than the rubber material. Using the Westly bandage for skin wounds may result in substantial heat loss due to the location of the skin at the exterior of the body.
Adequate heat transfer at the site of a wound is the subject of several patents. Eidus (U.S. Pat. No. 3,596,657, August 1971) describes a thermally conductive surgical dressing consisting of conventional cotton gauze interwoven with high conductive metallic thread. The metallic thread offers high thermal conductivity for removing heat from a surgical wound or injecting heat into a surgical wound using either ice packs or heating packs. Augustine et al (U.S. Pat. No. 6,235,047, May 2001) describes a thermally conductive bandage consisting of a polymeric layer which absorbs water enhancing thermal conductivity. Both devices basically sit on the wound and immediate skin area (periwound) only. They do not extend to other skin areas in the general area of the wound. Since the Eidus device utilizes a mesh of cotton interwoven with metal thread, the thermal conductivity will still be significantly lower than for mesh made entirely of metal or a metal sheet. The Augustine device uses water as the primary thermal conductor. Water is a good thermal conductor compared to air but a very poor thermal conductor compared to all high thermal conductive metals such as silver, copper, gold, and aluminum. Aluminum which is the least efficient conductor of the metals mentioned above, still has a thermal conductivity which is almost 400 times greater than pure water (237 W/M oK for water). Neither of these two patents is intended to conserve body heat and distribute it to the wound. Both use external heat sources to heat the wound.
SUMMARY OF INVENTION
Medical research has found that the best conditions for wound healing are those which duplicate as closely as possible normal physiological conditions. This includes wound temperature, which is optimized when it is as near to the normal core physiological temperature of the human body (37° C.) as possible.
Due to the inadequate transfer of oxygenated blood to the area of chronic wounds, the temperature of the wound is normally below that of healthy skin in nearby locations. Even healthy skin exhibits surface temperatures which are below the body core temperature due to heat loss. This problem is exacerbated for chronic wounds at locations where the soft tissue is normally very thin, as in the shin of the leg, big toe or heel of the foot, and other areas where bond protrusions are very close to the outer skin. In order to bring the wound temperature as close to the body core temperature (37° C.) without the use of externally applied artificial heat, the present invention utilizes basic principles of heat transfer to both conserve body heat in the vici
Chen Tony D.
Hamilton Lalita M
Lucchesi Nicholas D.
Rozsa Thomas I.
LandOfFree
Insulator-conductor device for maintaining a wound near... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Insulator-conductor device for maintaining a wound near..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Insulator-conductor device for maintaining a wound near... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3071407