1. Field
Our invention is in the field of bed accessories, and particularly relates to an application for relieving the adverse effects of inadequate hospital-bed mattresses upon orthopedic patients who have back problems.
2. Prior Art
A normal hospital-bed mattress is relatively inadequate for an orthopedic patient being treated for spinal disorder. Even when new, a mattress designed for the average hospital patient is too soft or compliant for the back-trouble patient. Such a mattress does not adequately transmit the firmness of the underlying bed frame and panels to support the patient's spine. On the other hand, a mattress suitable for a patient with back trouble would be too firm or stiff and thus a problem for most other patients.
One approach to these varying requirements would be to use specially made mattresses, offering firm support, for orthopedic patients with bad backs--while using normal mattresses for other patients. However, in hospital use this would normally be considered impractical. It would entail relatively frequent interchange of mattresses, because the beds even in an orthopedic ward are used in turn by patients with and without spinal complaints. Since mattresses are both quite heavy and quite bulky, the option of using different mattresses would call for added labor, storage facilities and possibly special equipment--all costly and complicating factors unacceptable in most hospitals.
An additional major problem area arises from the fact that a typical hospital bed has an articulated frame permitting upward tilting of the frame portion beneath the patient's back and head; it may also have a stationary horizontal portion beneath the patient's buttocks, an upward tilting of the portion beneath the patient's thighs, and a downward tilting of the portion beneath the patient's lower legs. Usually a rigid or semirigid panel spans each frame section, so that when the sections are all horizontal the bed resembles a segmented tabletop. Typically the mattress of such a bed is continuous and simply is disposed atop the articulated frame and panel where it must bend or fold to accommodate the articulated action of the frame and panels.
The mattress is subject to deterioration from use, particularly in the area where it bends, due to repeated flexure and disintegration of the padding material and springs. Interacting with this flexture and disintegration are the weight distribution and movements of a patient lying on the mattress. The padding, as a result, seems to migrate; whatever the mechanism, it forms lumps and soft areas and provides uneven and inadequate support for the patient. While this condition is not confined to the bending area, it is most severe there.
In that same area the rubberized or plastic mattress cover tends to develop ripples or creases which then become relatively permanent. These creases add to the patient's discomfort through chafing and may actually cause abrasions; to escape the concentrated effects of the creases on a particular part of the body the patient may shift into an awkward position in which the body is not properly supported--leading inevitably to even greater and more-fundamental discomfort.
All of these effects are exacerbated for back patients, especially if protracted confinement is required. In such a case it is essential to maintain generally uniform support for the length of the spine. In particular, if the lower part of the spine is not adequately supported relative to the upper portion, the spine tends to bend or distort.
Even a relatively thin foam pad placed directly on the hard metal tabletop-like surface of a typical articulated hospital bed would be preferable to the deteriorated normal mattresses found on such beds. However, such a solution (as with the mattress-changing technique described above) is impeded by the costs of mattress moving and storage.
The prior art reflects efforts to overcome these problems, but teaches away from the concepts of our invention--some of the oldest art presenting the most similar structure, though the similarity is superficial.
U.S. Pat. No. 46,569, issued Feb. 28, 1865 to R. H. Mathews illustrates a portable "bedstead" for use of invalids, and for maternity cases in actual delivery. This "bedstead" comprises a continuous, relatively thin cushion and an articulated thin backing secured to the cushion, providing easy means for the attendant or physician to maneuver the patient between lying and sitting positions. Foot-blocks, and handles for use by either the patient or attendant, are included. For carrying, the apparatus folds into a configuration which is quite compact; it has straps for securing it in the folded configuration and handles for carrying it in that condition. The device is described as "put . . . into use by laying it on a common bedstead or any article that will sustain it"--i.e., likely a flat bedstead, workbench or the like.
The folding action of Mathews' device is not coordinated with that of any underlying articulated bedstead, if indeed such beds were then in general use or even general hospital use. To the contrary, the inventor noted that his "sick bed or frame [could] be converted into the form of a chair by shifting it, with the patient thereon, toward the edge or side of the bedstead on which it lies, so as to allow the legs of the patient to hang down, the feet resting on the foot-blocks . . . . The handles . . . afford every facility in moving and turning the frame with its burden without touching the patient." In short, Mathews' structure was not directed to the same purposes as the present invention, and accordingly its details reflect different constraints, as will be seen.
Composites of cushioning and backing materials for various purposes are of course well-known, an early example of modern technology appearing in British Pat. No. 490,461, which issued Jan. 11, 1937 to F. De. Lautour: "A sheet or board of gas-expanded rubber or rubber-like materials is faced on one or both sides with a wood-veneer or plywood board."
Somewhat more closely related purposes characterize the inventions of A. W. Schenker, protected under U.S. Pat. Nos. 2,373,421 and 2,469,084, issuing respectively Apr. 10, 1945 and May 3, 1949 and described as "body resting appliances." These inventions involve combined cushioning and thin reinforcing materials, forming a composite structure for comfort and for spinal or other skeletal therapy. The special feature of Schenker's inventions seems to be custom molding of the reinforcing material to the contours of a particular patient's body, for optimum stress distribution and skeletal support.
The later of Schenker's patents discloses a version which is articulated in the manner of a conventional hospital bed, the reinforcement being embedded between two cushioning layers which produce overall thickness generally comparable to that of a conventional mattress.
Schenker's inventions thus are intended to substitute for existing conventional hospital mattresses rather than to cooperate with, and extend the beneficially useful lives of, such already-existing mattresses. In these ways Schenker's inventions are distinguished, as will be seen, from ours.
More-modern approaches to the problem of deteriorating hospital bedding are seen in U.S. Pat. Nos. 3,188,660 and 3,249,952, issued respectively June 15, 1965 to Y. R. Guttman and May 10, 1966 to M. N. Janapol.
Guttman contributes the concept of sectionalizing the mattress cushion itself at one point, to match the principal articulation of the bed frame. This approach reduces the flexure of the padding material in that area, expectably reducing to an extent the formation of lumps and pockets. But Guttman does not reduce the component of the mattress disintegration which results from the interaction of the patient's weight and movements with the mattress-section tilting; eventually this too causes the mattress to become lumpy. Moreover, unless extreme care is taken to position the mattress sections properly and monitor their condition, over the long term the separate edges of the mattress sections which are exposed where they abut at the base of the patient's spine, and are subject to at least slight misalignment, may produce as much patient discomfort and eventual spinal distortion as a conventional unitary mattress, if not more.
Janapol's technique is to facilitate articulation of the mattress without actually separating it into distinctly fabricated sections. He teaches drawing down or retracting the padding material of the mattress into a laterally extending recess in the frame, at the point of the principal hinge; and separating the mattress padding into layers with low-friction interfacing, so that the layers slide upon each other rather than catching, bunching and wrinkling. By this construction the inventor purports to control the flexure and consequent disintegration of the padding. Without evaluating the merits of this design, one may see immediately that it is a very different kind of solution to the hospital-bed problem from our invention.
A possibly closer relative in that it supplements an existing mattress in an "egg-crate foam" overlay intended to be placed on top of an existing hospital mattress. This overlay is a large piece of plastic foam, molded into a cellular structure reminiscent of the paper-fiber separators used in crating eggs. The "egg-crate foam" does not include any type of firm backing or stirrener. Thus this construction may provide a softer support for delicate skin, rather than firming or stiffening the support, and thus offers a teaching directly contrary to that of our invention, while serving very different purposes.