U.S. patent number 3,893,198 [Application Number 05/239,219] was granted by the patent office on 1975-07-08 for mattress for preventing bedsores.
This patent grant is currently assigned to Medic-Ease Corporation. Invention is credited to E. Allan Blair.
United States Patent |
3,893,198 |
Blair |
July 8, 1975 |
Mattress for preventing bedsores
Abstract
A mattress is constructed of foam having a 50% compression
deflection pressure equal to the body weight of an average patient
divided by his projected body area and a thickness in excess of his
body depth, to prevent bedsores by providing a moldable surface
which spreads support to a great area of the patient's body. The
mattress surface supporting the patient is subdivided into a
plurality of individual load bearing units to provide lateral give
to the mattress. A water proof cover sheet fits over the mattress
and includes means for tightening the cover about the mattress to
provide a firmer mattress for maneuvering the patient.
Inventors: |
Blair; E. Allan (Princeton,
NJ) |
Assignee: |
Medic-Ease Corporation
(Princeton, NJ)
|
Family
ID: |
22901148 |
Appl.
No.: |
05/239,219 |
Filed: |
March 29, 1972 |
Current U.S.
Class: |
5/699; 128/889;
5/697 |
Current CPC
Class: |
A61G
7/05707 (20130101); A47C 27/005 (20130101); A47C
27/14 (20130101); A47C 31/105 (20130101) |
Current International
Class: |
A47C
27/14 (20060101); A47C 21/00 (20060101); A47C
21/06 (20060101); A61G 7/057 (20060101); A47c
023/00 (); A47g 009/00 () |
Field of
Search: |
;5/DIG.2,336,345,355,361,361B,334,334C,334R,345R,361B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gilliam; Paul R.
Assistant Examiner: Calvert; Andrew M.
Attorney, Agent or Firm: Miskin; Howard C.
Claims
What is claimed is:
1. A mattress for the prevention of bed sores in a user comprising
a unitary member made of resilient foam having a thickness greater
than the thickness of an average user's body and having
load-bearing properties wherein a 50 percent compression deflection
pressure is substantially equal to the user's body weight divided
by his body area in contact with the mattress, said mattress being
subdivided upon its surface into a plurality of individual
load-bearing units whereby said mattress absorbs the downward
weight and lateral movement of the user's body to protect said
user's body from contact with hard surfaces and from localized high
pressure over the bony protuberances, a cover of flexible,
waterproof and soft but strong fabric which is sized to cover the
top and overlap, all edges of said mattress which is loose enough
that it is not pulled tight when the user sinks deeply into the
mattress, means for drawing at least two opposed edges of the cover
tightly about the mattress so that the mattress is rendered firm
enough to easily move a patient disposed thereupon, said drawing
means includes a plurality of straps affixed to one edge of said
cover and a plurality of buckles affixed to an opposed edge of said
cover, said straps being extended thereunder, a shaft disposed
beneath said mattress, said straps being wrapped about said shaft
and means for rotating said shaft whereby the tension upon said
straps may be adjusted in unison.
2. The mattress recited in claim 1 wherein said rotating means
includes an electric motor.
3. A mattress for the prevention of bed sores on a user comprising
a unitary member made of resilient foam, having a thickness greater
than the thickness of an average user's body and having
load-bearing properties wherein a 50 percent comparison deflection
pressure is substantially equal to the user's body weight divided
by his body area in contact with the foam, said foam absorbing and
distributing the downward weight of the user's body by allowing the
body to sink deeply into the foam and avoiding localized high
pressure being applied to body protuberances, and means for lifting
the user's body lying on the foam including a cover of pliable
material which rests on the surface of the foam beneath the user's
body without being secured to the foam and being loose enough so
that it is not pulled tight when the user sinks deeply into the
foam, said user being supported solely by the foam during use, and
means attached to the cover for drawing at least two opposed edges
of the cover apart to make the cover taut while the user is
disposed thereupon without applying any force to the foam beneath
the user to easily move the user sunk in the foam.
4. The mattress recited in claim 3 wherein said drawing means
comprises a plurality of straps affixed to one edge of said cover
and a plurality of buckles coupled to an opposed edge of said
cover.
5. The mattress recited in claim 3 wherein said cover is
waterproof, soft but strong fabric.
6. The mattress recited in claim 3, wherein said cover tautening
means includes a plurality of straps and means for tightening the
straps.
7. The mattress recited in claim 6 wherein said strap tightening
means including a shaft and means for rotating said shaft.
8. The mattress recited in claim 6 wherein said cover tautening
means further includes buckles, said straps being extended under
said foam.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a mattress for preventing the formation
of decubitus ulcers or bedsores as they are popularly known.
2. Description of the Prior Art
Decubitus ulcers or bedsores are a common problem among people who
are paralyzed, in a coma, or chronically bedridden, e.g., 10 to 15%
of all bedridden patients develop bedsores. They are a major
economic problem among individuals in the categories above and they
cause great incapacitation and even death to the people who suffer
from them. Generally, bedsores occur over the bony protruberances
of the body, such as the sacrum and shoulder blades on the
posterior, the iliac crest on the anterior, the greater trochanters
on the sides, the knees on the legs and the heels on the feet,
i.e., areas where the skin is compressed between hard bone and a
hard mattress.
Many methods have been used to treat or prevent bedsores. Turning
the patient every 2 hours to allow reestablishment of circulation
over the bony protruberances is generally used, but this method
increases the work load of the nursing staff and interrupts the
patient's rest. Furthermore, in some cases it is not possible to
turn a patient because of specific injuries. Sheepskins are often
used to allow ventilation and minimize pressure but this creates
severe cleaning problems, since the decubitus ulcers often bleed or
drain, and patients who have them are often incontinent. This means
that the sheepskins must be laundered frequently and they are very
difficult to launder.
Other devices attempt to alleviate bedsores. One such device is an
air-mattress in which the air pressure is applied alternately to
adjacent tubes. This transfers the pressure from one spot to
another allowing circulation to be reestablished. This method has
the disadvantage of requiring a device for providing an alternating
air supply.
A device for providing a soft supporting surface is the water
mattress. However, water mattresses have the disadvantage of being
extremely heavy, cold, difficult to fill, prone to leakage and
their softness makes it difficult to move the patient about on
their surface. Further, when a patient lies in a prone position the
cover of the mattress closes around his face causing the patient
psychological distress and limiting his free breathing. Also,
catheters, which may be attached to a patient, will not drain
freely because the tube must rise to pass over the edge of the
water mattress. These problems make the water mattress the least
used solution to bedsores, even though it is the most effective in
providing a soft surface.
SUMMARY OF THE INVENTION
This invention concerns a mattress which has all the desirable
properties of the water mattress for the prevention of decubiti,
without any of its liabilities. It consists of a mattress of a
polyurethane or similar foam, having a 50 percent compression
deflection pressure equal to the user's weight divided by the
projected area of his body in contact with the mattress and a
thickness greater than the depth of his body. This is an
exceedingly soft foam, having an RMA firmness of 13 to 23.
Normally, mattresses are made with an RMA firmness of 23 to 35. If
a mattress having an RMA firmness below 23, is made in the normal
thickness of 4 to 6 inches, the person lying on it finds it
uncomfortable because he sinks in to the point where he feels the
hard supports for the mattress. On the mattress described in this
invention, however, the hard support for the mattress is not felt
because the person lying on it does not sink in to more than
three-fourth of its depth.
A foam mattress having a total thickness of 12 inches may be
incised in a pattern to a depth of about 4 inches to provide
further softness and decrease resistance to lateral movement. If
the incisions are too deep or too close together, the cut edge of
the foam curls into them and forms ridges. Thus, the incisions
should be about 7 inches apart. Further, no incision should be
centered on the longitudinal axis of the mattress, since the
patient tends to settle into such an incision thus losing the
support of the mattress. It is also preferred that the incisions
not reach the edge of the mattress and no incisions are necessary
in the head area while the incised pattern may be smaller in the
foot area. The head area is cut dowh by a depth of about 4 inches
to a thickness of about 8 inches, to allow greater comfort for a
patient in the prone position, to allow the neck to remain in a
neutral position, and to avoid having the face buried in the
mattress.
At the area of the hips, a notch about 7 inches wide and 6 inches
deep is cut into the unincised edge of the mattress up to the
incised area. A catheter tube can be placed in that notch, thereby
allowing it to drain freely when the patient is in the prone
position.
Such changes in the surface of the mattress as the cut-out head and
catheter tube channels cannot be made on a water mattress.
With such a mattress, in accordance with the invention, the
patient's body sinks very deeply into the mattress, with his weight
uniformly distributed over the length of his body rather than
concentrated on his bony protruberances. Thus, paraplegics may lie
on this mattress either prone or supine for unlimited time, without
exhibiting any erythema over the bony protruberances. Since
erythema is the invariable precursor of decubitus ulcers, it is
clear that this mattress eliminates the need to turn the patient to
prevent decubiti, when the patient is in the prone or supine
position and requires no preventative methods other than the usual
appropriate good nursing practices.
A further aspect of the invention is a waterproof cover for the
mattress, which is loose fitting and soft and pliable enough so
that the patient's weight is supported solely by the mattress and
not by the cover. The cover has straps attached to and extending
from one side which go under the bed frame, and fasten into
clamping buckles which are mounted on straps attached to the other
side of the cover. Thus, this cover serves two functions: It
protects the foam mattress from being soiled by the patient and, by
tightening the straps, the mattress may be made firm so that the
patient can be easily turned or moved.
Tightening can be either accomplished manually or a mechanical
device may be used which consists of a rod or shaft running the
length of the bed, around which the straps are looped. The shaft
can be rotated mechanically, thereby tightening the straps and
cover. For manual operation, the straps are simply pulled tight
through the clamp buckles by hand.
To loosen the cover again so that the mattress recovers its normal
softness, the buckles are either released manually or the shaft
rotated to its normal position depending upon the tightening
method.
The mattress as described above in accordance with the invention
also serves the purpose of allowing skin grafts to heal while the
patient is lying on them and contributes greatly to comfort in
orthopedic and surgical cases in which localized pressure on
injured tissue or bones causes discomfort. It may also aid in
muscle relaxation.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment of the applicant's invention will now be
described with reference to the drawings in which:
FIG. 1 is a top view of a mattress in accordance with the invention
showing the cover sheet partially removed;
FIG. 2 is a front view of the mattress of FIG. 1 shown in place on
a hospital bed from the top end thereof showing one method of
tightening the cover; and
FIG. 3 is a bottom view showing a second method of tightening the
cover.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a mattress 10 is illustrated in general which
may have appropriate dimensions to serve, for example, as a
hospital bed. The mattress 10 is formed of a plastic foam such as
polyurethane which has known softness and resilience. The foam is
chosen for its firmness so that at 50 percent deflection it will
produce an upward force substantially equal to the downward force
exerted by the weight of the average patient. Moreover, since the
mattress is formed of a pad of plastic foam material deeper than a
patient's body, e.g., 12 inches in thickness, it molds itself to
the patient's body thereby supporting the maximum area of his body
and relieving the usual supporting surfaces, such as the sacrum,
hips and heels, iliac crest and knees, from supporting the entire
body weight. For an average patient having a body weight of 150
pounds, and a body area in contact with the mattress of 500 square
inches which average weight and body dimensions are provided in the
publication "The Measure of Man, Human Factors in Design" by Henry
Dreyfuss, 2d ed. pub. 1967 by The Whitney Library of Design, 18
East 50th St., New York, N.Y. 10022, for an average pressure of
about 0.3 psi exerted by the body, the mattress should have a 50
percent deflection firmness of 0.65 to 1.2 psi, which corresponds
to an initial Rubber Manufacturer's Association firmness value of
13 to 23. Such a foam will soften in use to correct values of
firmness.
The above mentioned foam is not used in conventional mattresses
since it is found that in the conventional range of mattress
thickness, 4 -6 inches, a firmer foam is necessary to avoid contact
between the mattress user's body and the supporting surface for the
mattress.
The mattress 10 is subdivided into a plurality of load bearing
units 12 which may be squares having an edge dimension of 7 inches.
These square are defined by incisions 14 formed in the upward
surface of mattress 10 which, in turn, may be approximately 4
inches deep. The load bearing units 12 have lateral give, due to
the incisions 14, and thus when a patient's body moves laterally
the shearing effect between his skin and tissues caused by the
frictional resistance of the supporting surface to lateral movement
is greatly reduced.
Since the incisions 14 would produce a structural weakness if
continued to the sides of mattress 10, the incisions stop before
all side areas 16 of the mattress. At the level of the hips a notch
43 at least 6 inches wide and 6 inches deep is cut into the side
area extending all the way to the incised area (on each side of the
mattress 10). These notches form a path for the catheter tube,
thereby allowing the cather tube to drain freely when the patient
is in the prone position. Further, to prevent the tendency of a
patient to fall into a slit arranged along the central axis of
mattress 10, there is no longitudinal slit along the length of axis
18.
The feet of a bed ridden patient under the heels due to the high
pressures caused by body movements, are particularly subject to the
shearing effect described above. Thus, in region 20 which
corresponds to the foot of mattress 10, a smaller grid pattern is
formed having square load bearing units 22 with an edge dimension
of about 31/2 inches. Further, since bedsores are rarely a problem
on the head, the grid pattern at the head area 21 may be
discontinued without harm to the invention.
The head area 21 of the mattress 10 as shown in FIGS. 1 and 2 is
cut down across the entire width of the mattress 10 to a depth of
about 4 inches. This leaves a thinner section of 8 inches of the
mattress at the head area 21 and allows the patient's neck to be in
a neutral position when he is lying prone, preventing his head from
being sunken into the mattress, as it is in a water mattress.
The mattress 10 described above is covered by a cover 24 of
waterproof soft material such as 1.1 ounces per square yard of
ripstop nylon coated with polyurethane, vinyl or rubber. As can be
seen in FIG. 1, the cover 24 extends beyond all the edges of
mattress 10 so that when the patient sinks deeply into the mattress
the cover is not drawn tight on the mattress. In addition, straps
26 are attached at intervals of, for example, 10 inches, along one
edge of the cover starting 18 inches from the head of the mattress,
and registering straps 28 having buckles 30 are arranged at the
corresponding places at the other side of the cover.
As is seen in FIG. 2, the straps 26 and 28 may be arranged under
the side rails 32A and 32B of a hospital bed 34 and drawn together
with buckles 30 to provide a firmer surface 36 upon which a patient
may be more easily turned as for bathing. The straps 26 may be
alternatively wrapped around a shaft 38 as shown in FIG. 3. Thus,
by rotating shaft 38 all the straps 26 may be tightened or loosened
in unison. Shaft 38 may be rotated by hand crank 40 shown in FIG. 2
or by other known means such as an electric motor 41 and
transmission 42 shown in FIG. 3.
While the above description fully covers the preferred embodiments
of the applicant's invention, many modifications may be made within
the scope of this invention. Thus, for example, the surface of
mattress 10 may be contoured to fit a patient's body.
* * * * *