Chairs and seats – Bottom or back – Framework
Patent
1983-10-13
1986-05-13
McCall, James T.
Chairs and seats
Bottom or back
Framework
5450, 297DIG1, 297452, A47C 702
Patent
active
045882290
DESCRIPTION:
BRIEF SUMMARY
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to a seat cushion for the human body which comprises a pad comprising a flexible envelope containing a fluid filling material, which pad is adapted to be used in combination with a shaped tray. In the preferred embodiment, the envelope of the pad is an extensible elastomeric material and the pad is partitioned or segmented to limit the flow of the fluid filling material in selected areas of the pad.
BACKGROUND OF THE INVENTION
Patients who are immobilized for any number of reasons are prone to develop pressure sores at any point in the body wherein a load bearing bone of the body is adjacent to the underlying support structure. Pressure sores are defined as localized areas of necrotic tissue over bony prominences. Particularly susceptible to pressure sores are patients who are victims of stroke, hip fracture, spinal cord injury, and brain injury, as well as paraplegics, and geriatrics. The successful cure of pressure sores requires daily care and debridement for a period of many months. In some cases, surgical skin grafting is necessary. The apparent problems and costs of treating a single pressure sore are great and therefore prevention must be considered a prime factor.
It has been estimated, that when seated on a flat surface, up to 75% of a person's body weight is distributed over an area covering only four square inches. This is the area of the ischia or seat bones. For a person weighing 150 pounds, this means as much as 110 pounds pressure is distributed over four square inches, or over 25 pounds per square inch pressure. It is also estimated that the capillary blood pressure, when seated, is about 40 millimeters of mercury or about 0.8 pounds per square inch. If pressures higher than 40 millimeters or mercury are developed during sitting, it is obvious that flow of blood through the capillaries can be restricted, which produces a much higher probability of developing pressure sores or decubitis ulcers.
The prior art has attempted to relieve the occurance of pressure sores on the human body by supporting the human body on large bodies of liquid, to distribute the supporting force uniformly all over the supported body. These attempts have been successful to a limited extent. However, in order to provide for complete support, it is necessary to displace a weight of liquid equal to the weight of the body being supported. Consequently, such systems are very heavy and are difficult to employ even in beds. Moreover, such heavy liquid cushioning devices have been found difficult to manipulate by patients who utilize wheel chairs to afford them a reasonable degree of mobility and independence, particularly when it is necessary to fold a wheel chair up when it is transferred by automobile.
The prior art systems have disclosed the use of air bags and air tight envelopes which sometimes include a mass of compressible, resilient material to augment the support, see for example U.S. Pat. Nos. 1,332,933, 2,997,100, 3,870,450 and 4,005,236. Other systems have included elastomeric foams which are filled with liquids, see for example U.S. Pat. Nos. 3,611,455, 3,702,484 and 3,965,508. While both of the liquid and gas (air) systems have been successful to some extent in distributing the body load over a wider surface of the body, both suffer from inherent disadvantages. Those fluid filled systems which rely on air tight or water tight envelopes are subject to inadvertent punctures and deflation with the resulting loss of support. The systems based on the use of liquid fillings are invariably heavy and are difficult to use in a wheel chair or other ambulatory devices. Moreover, the systems which rely on air or other gas for support need frequent adjustment to compensate for temperature variations, pressure variations (such is caused by altitude changes) and the weight of the user.
In addition to the foregoing problems, the prior art seat cushions do not provide sitting stability or posture support to the user. Problems with seat stability are particula
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Egan Donald E.
Jay Medical Ltd.
McCall James T.
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