Methods and devices for reducing stress concentration when supporting a body

Abstract

This invention is of a method and equipment for reducing stress concentrations in a body supported in a horizontal or any reclining position up to and including a fully seated position. The stress reduction is accomplished by means of specially designed or arranged cushioning material contained inside a membrane or bladder wherein the pressure of a fluid inside the membrane can be controlled as a means of varying the cushioning effect (compressibility) of the material inside and holding the cushioning material in specific places to reduce fight-back of the material over supporting edges that may otherwise create undesirable shear on the supported body tissue.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] Not applicable STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable REFERENCE TO A MICROFICHE APPENDIX [0003] Not applicable BACKGROUND [0004] A person who is elderly or has some enervation and is confined to bed for an extended period, will have a propensity to develop tissue trauma sores (ischemic ulcers, decubitus ulcers or bedsores). Typically these sores appear over bony prominences where forces arising from the weight of the body are concentrated and the lack of movement leads to tissue destruction. (Those with normal sensation and mobility become “uncomfortable” and move to a different position while those under anesthetics can't move) To avoid such sores, some form of tissue pressure / shear interface should be provided to reduce these forces to a value that the tissue can tolerate. These tissue trauma forces may be adjusted in a number of ways; by “putting the load where the body can tolerate it”,...

AI Technical Summary

Benefits of technology

[0041] This invention relates to the support of a person in the prone, supine, sidelying, semi reclined or sitting position without the usual stress concentrations which may lead to tissue trauma, decubitus ulcers or bed sores. It is an object of the present invention to provide support for a human body in a manner so that the forces of support have fewer concentration points which are likely to occur at or near bony prominences, nerves, or tendons, and which, if not accommodated, can lead to serious complications such as bed sores, nerve damage, or strained tendons.

[0042] This invention addresses the stress distribution problem by combining several techniques. First, using a basic foam inner material, or other that gives a similar performance, the invention provides regions where material has been cut in some selected manner, cut away, omitted, or formed to reduce the magnitude and abruptness of any stress concentrations when supporting a body. This technique is then combined with the process of applying a membrane over the insert material to smooth out the localized variation in stress and concomitantly, if the membrane is able to control the amount of air or fluid surrounding the space between the bladder and interstices of the foam, the fluid pressure may be varied to change the characteristics of the foam itself. This can be characterized by reviewing U.S. Pat. Nos. 5,127,119 and 5,048,137 by Rogers and observing that if these patented products were loaded by a body, the foam will “fold” over “normally” to the tissue of the body to reduce the shearing occurring at the tissue. However, if a bladder were to also be placed between the body and the supporting foam discussed, the bladder, with air control ability, can hold the foam in its desired place without the normally concurrent fightback of the foam and thus the “shear” or pressure known to damage the tissue, nerves, and tendons. The body is virtually floated by a high specific gravity through a combination of foam, bladder and fluid pressure. But, the foam or supporting medium must be previously pre-shaped for this system to work as designed.

Problems solved by technology

Such discomfort and possible injury is a direct result of the stress concentration created by the non-uniform shape of the human body.

However, this does not mean that a uniform distribution of stress is the most desirable result.

Although it has been generally recognized that a support structure for the human body needs to provide different stress patterns in different areas, most schemes do not fully achieve it.

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