Heat exchange – Flexible envelope or cover type
Reexamination Certificate
2002-11-04
2004-08-10
McKinnon, Terrell (Department: 3743)
Heat exchange
Flexible envelope or cover type
C607S096000, C607S108000, C607S114000, C005S421000, C005S655500
Reexamination Certificate
active
06772825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present device is a cooling support surface with a central, refrigerant-containing bladder bordered by flexible thermal conductive pathways for improving a user's comfort, reducing the likelihood of ulceration, or promoting the healing of bedsores.
2. Background Information
Often, restless sleepers are awakened many times during the night when they become overheated. They uncover themselves, drift off back to sleep, and are reawakened because they are shivering, so they cover up again, and the cycle repeats itself. Another body and temperature-related problem occurs in the cockpit, or in a truck or taxi cab, where high ambient temperatures cause the pilot or driver to sweat and feel faint. He or she is often too busy or trapped behind the wheel and cannot find relief. In addition to physical discomfort, such problems can become severe enough to impair performance and cause accidents. The present cooling support surface provides relief for healthy sufferers, and also for medical patients with more complicated temperature-related or bed bound-related problems.
Bedsores, or decubitus ulcers, can be a serious problem in bedridden or wheelchair-bound patients, particularly for people who are paralyzed, emaciated, post-surgical, elderly, emaciated, or diabetic. Bedsores are a common and persistent problem for those who have to spend a great deal of time in bed, and for their physicians and nurses. As baby boomers age, the elderly population increases, and the ordinary bedsore becomes more of a problem. Bedsores can penetrate to the muscles and bone and are surprisingly life-threatening on occasion. Where, for example, a geriatric patient in a fetal position develops bedsores between his knees, an infected bedsore can become gangrenous and necessitate amputation of a limb. Bedsores can progress to necrosis, septic arthritis, pathologic fracture, and septicemia.
To avoid bedsores, nurses or nurse assistants turn bed-bound patients at prescribed intervals, inspect their skin and apply creams, give massages and baths to patients, exercise limbs, and promptly change wet bed sheets and bedclothes. Patients are placed on air-filled mattresses, sponge rubber “egg crate” mattresses, silicone gel or water mattresses, mattresses filled with fluid or tiny spheres, or Stryker turning mattresses. Protective padding, such as sheepskin or pillows, is placed on bony prominences under braces, casts, etc. Topical ointments, dressings, debridement, and antibiotics are prescribed to curb infections in decubitus ulcers. Prevention and management of bedsores is nevertheless difficult, and further aids are needed.
Bedsores are ordinarily developed over the bony prominences of the body, such as the heels, sacrum (tailbone), ischia, greater trochanters, and ankles (external malleoli). It has been found that bedsores are less likely to form where the skin above the bony prominences is maintained at a slightly cooler temperature than normal skin temperature. The normal core temperature (“normothermia”) of the human body is between 36° and 38° C. Skin temperature typically ranges between about 32° C. and about 38° C., depending on ambient temperature, the amount and type of clothing being worn, the core temperature, and where the skin is located on the body. On a typical mattress, seat cushion, seat back, etc., heat is trapped between the body and the covered skin surface and the skin temperature rises rapidly to and is maintained at between about 36 and 38 degrees C. It is believed that skin temperatures in this range promote soft tissue breakdown by increasing tissue metabolism, promoting local perspiration, which wets and weakens the stratum corneum (surface layer of the skin), and increasing friction and shear forces between the sweaty skin and the bedding and/or clothes between the skin and the support surface.
In contrast with a conventional mattress or other resting surface, such as a wheelchair seat cushion or seat, the support surface of the present invention distributes heat away from the user's body during the support period. This keeps the user comfortable while sleeping or sitting, particularly under the user's bony prominences, where bedsores are more likely to form. Relative cooling is accomplished in the present invention with a central, refrigerant-containing bladder connected to thermal conductive pathways that distribute heat from this central bladder to the cooler periphery of the support surface. Cooling is ideally held to a narrow temperature range just below normal skin temperature, since cold temperatures are uncomfortable and undesirable, particularly where the patient is emaciated or otherwise infirm. Thus, in addition to making the user more comfortable and possible preventing accidents and failed missions, the present invention reduces the likelihood of bedsore formation, and aids in the healing of early stage bedsores or other skin ulcers that the user may already have. Since the user's skin is held to a temperature below perspiration threshold (approximately 92 degrees Fahrenheit), the user is relatively free of perspiration and stays more comfortable.
BRIEF SUMMARY OF THE INVENTION
A heat exchange support surface for added comfort, maintaining a cool skin temperature, or reducing the incidence and promoting the healing of bedsores, includes:
(a) a central portion comprising a hollow, enclosed bladder containing a pre-determined amount of liquid refrigerant, the refrigerant having a boiling point between about 23 and about 35 degrees Centigrade;
(b) a flexible spacer mechanism contained in the bladder, the spacer mechanism separating an upper bladder wall from a lower bladder wall; and
(c) thermally conductive end portions attached to opposite ends of the bladder, the conductive end portions comprising a flexible heat conductive material layer.
In an alternate embodiment, a seat/back support surface for comfort and maintaining cool, dry skin, includes:
(a) a central, hollow, enclosed bladder containing a pre-determined amount of liquid refrigerant, the refrigerant having a boiling point between about 23 and about 35 degrees Centigrade, the bladder being enclosed in a generally horizontal base of the seat;
(b) a flexible spacer mechanism contained in the bladder, the spacer mechanism separating an upper bladder wall from a lower bladder wall;
(c) at least one length of flexible tubing attached at both ends into the bladder, the length of tubing extending through a generally vertical back of the seat; and
(d) a pump in the seat base for pumping a pre-determined amount of the liquid refrigerant up the seat back through a rear section of the length of tubing.
In another alternate embodiment, a seat/back support surface for comfort and maintaining cool, dry skin, includes:
(a) a hollow, enclosed bladder containing a pre-determined amount of liquid refrigerant, the refrigerant having a boiling point between about 23 and about 35 degrees Centigrade, the bladder being enclosed in a generally horizontal base of the seat;
(b) a main body above the bladder, the main body being comprised of two same-sized, generally rectangular-shaped sheets of a durable, flexible, gas-impermeable material strong enough to contain the refrigerant, the main body sheets being sealed along their edges, except for at least one opening at an upper end and at least one opening at a lower end of the main body, the main body comprising a plurality of channels with staggered openings for allowing the passage of the liquid refrigerant, the main body being on a back of the seat;
(c) at least one length of flexible tubing attached at an upper end to the at least one upper main body opening and at an opposite end to the at least one lower main body opening, the length of tubing extending through the seat back; and
(d) a pump in the seat base below the bladder for pumping a pre-determined amount of the liquid refrigerant up the seat back through the length of tubing.
REFERENCES:
patent: 4596250 (1986-06-01), Beisang, III et al.
patent: 4651369 (1987-0
Lachenbruch Charles A.
Lachenbruch Roger B.
Harleston Kathleen M.
Harleston Law Firm LLC
McKinnon Terrell
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