Low friction bed pad

A bed pad structure is provided for the prevention of bed sores or pressure ulcers. The bed pad includes a pouch portion having an upper layer formed from a porous low friction material and a lower layer formed from a flexible impervious sheet material. The pouch portion is further constructed to enable easy insertion and removal of a lubricated insert in between the upper and lower layers. Lubrication from the insert can flow through the porous upper layer. The low friction characteristics of the upper layer plus the presence of the lubricant adjacent the patient substantially prevents friction and related wear which are contributing factors to the occurrence of bed sores.

BACKGROUND OF THE INVENTION 
It is well established that recent medical advances have resulted in longer 
life expectancies. These changes in life expectancy when coupled with 
changes in population levels have yielded a population of elderly people 
that is much greater than ever before. For example, it is estimated that 
in 1902 about 2 million people in the United States were at least 65 years 
old. The latest census, however, reveals that approximately 24 million 
people in this country are at least 65. It is expected that this trend 
will continue. 
Despite the ability to keep people alive longer, the human body still 
undergoes substantial changes as part of the aging process. The changes 
which are attributable to aging include changes to the capillaries in and 
near the skin, changes to the muscles and tissues below the skin, and 
changes to the resiliency of the skin. As a result of these changes in and 
near the surface of the skin, an elderly person who is confined to bed for 
an extended period of time is likely to develop the decubitus ulcers or 
pressure ulcers which are commonly known as bed sores. Bed sores are an 
ancient problem which recently have begun to reach catastrophic 
proportions due to the growing number of elderly people. 
Bed sores are open ulcerations which generally appear in the skin which 
covers a bony prominence. Additionally, bed sores typically occur at 
weight bearing parts of the body. Since bed sores are most prominent among 
bed ridden or wheelchair ridden elderly patients the ulcers are most 
likely to appear on portions of the back which overlie prominent bones. 
For example in "Pressure Ulcers: Prevention and Treatment", Clinical 
Symposia, Vol. 31, no. 5, 1979, Agress and Spira estimate that 23% of bed 
sores occur adjacent the sacrum or lower spine, 24% are located at the 
base of the buttocks; 15% are located at the trochanter, which is located 
on the thigh bone in the vicinity of the hip; 8% are at the back of the 
heel; 7% at the ankle; 6% at the knees; 4% at the iliac crest, which is 
the front bony pretrusion of the hip; 3% at the elbows and 2% at the 
pretibial crest which is directly below the knee. Other significant areas 
of occurrence include the base of the skull, the chin and upper and lower 
portions of the back. 
Bed sores often are analogized to icebergs in that only the tip of a large 
ulceration breaks through the skin. More specifically in most instances, 
the bed sore not only effects the upper layers of skin but also the 
underlying layers of fat and muscle and perhaps even the underlying bone. 
Bed sores are extremely difficult to treat, are very painful and have a 
major negative effect on the quality of life for bed ridden elderly 
people. As pointed out by Agress and Spira, in extreme instances, 
bacterial infection of the bed sore may be life threatening. 
The name pressure ulcers implies that the principal source of bed sores is 
pressure. In fact the principal method for treating bed sores has been to 
eliminate or reduce pressure. For example many complicated and costly 
devices have been developed which effectively rotate patients periodically 
so that the weight bearing portions of the body are changed every few 
hours. Other devices and treatments have been developed to try to releave 
the pain and discomfort and to bring about healing of bed sores once they 
have occurred. These latter schemes have included the use of water beds, 
lambs' fleece and lambs' fleece treated with certain lubricating oitments 
and creams. None of these approaches have been very successful in either 
eliminating or treating bed sores. 
It is now known that pressure is only one of several contributing factors 
which cause bed sores in elderly bed ridden patients. Other significant 
contributing factors include friction and heat. Friction is the resistance 
to sliding motion of two bodies pressed against one another. The general 
term friction encompasses static friction, which results from the 
resistance to motion in overcoming inertia, and dynamic friction, which is 
created by the irregularities of the two surfaces interlocked with one 
another. A significant force is required to overcome static friction and 
thus to obtain sliding movement of two bodies with respect to one another. 
Static friction ceases to be a significant factor after sliding momentum 
has been achieved between the two bodies. However dynamic friction 
manifests itself in the rubbing together of microscopic projections on the 
respective bodies. More particularly the dynamic friction caused by 
microscopic irregularities in all surfaces causes heat in proportion to 
the load and speed and effectively welds adjacent surfaces at their points 
of contact, resulting in tearing or galling. 
When a soft material is pressed against a harder material and moved in 
sliding relation thereto, the softer material flows to conform to the 
topography of the hard material, thereby increasing the area of contact 
along with frictional forces and heat adjacent to the surface. 
In general, a softer material wears faster than a harder material. Certain 
flexible materials such as the skin of a young person are quite elastic 
and will give when subjected to the forces of friction. However in older 
patients the skin is less elastic. Furthermore, if the skin of the older 
person is subjected to frequent frictional forces, it becomes even less 
elastic. If an elastic material, such as skin, has a hard backing, such as 
a bony protrusion under the skin, the natural elastic deformation of the 
skin is severely limited. The net result is that wear to skin will occur 
much more quickly in areas of skin which cover a boney prominence. 
Wear of almost any surface subjected to friction is characterized by the 
removal of particles from the surface and by pitting. The loose removal 
particles causes further wear because of abrasion. Pitting of the surface 
further causes fatigue and weakening of the surface structure. Ultimately 
the wear attributable to friction eventually leads to fissures and cracks 
on the surface. Such faults if not treated immediately will grow because 
they are the weakest areas of the surface structure. 
Accordingly, it is an object of the subject invention to provide a 
composite structure which substantially prevents bed sores. 
It is another object of the subject invention to provide a composite pad 
structure with a very low coefficient of friction. 
It is an additional object of the subject invention to provide a composite 
pad structure for preventing bed sores which can be placed between a 
patient and a supporting structure. 
It is a further object of the subject invention to provide a composite pad 
structure for preventing bed sores which is comfortable to the patient and 
which cam be manufactured at a low cost. 
It is yet another object of the subject invention to provide a composite 
pad structure which includes a low friction fabric and a lubricant. 
SUMMARY OF THE INVENTION 
The subject invention simultaneously employs a low friction fabric with a 
lubricant. Lubricants are materials which have an ability to deform or 
sheer in the direction of motion of surfaces sliding adjacent to the 
lubricant. Consequently when a lubricant is disposed between two adjacent 
moving surfaces, the surfaces ride on a film of the lubricant, and most 
wear will actually be localized to the lubricant. 
The low friction fabric employed with the lubricant is a porous material 
having a coefficient of friction much lower than the coefficient of 
friction which normally occurs between skin and an adjacent surface of a 
bed sheet or clothing article. For comparison purposes, it is estimated 
that the coefficient of friction between human skin and a cotton sheet is 
approximately 0.6. The porous characteristics of the low friction fabric 
enables the lubricant to flow through the low friction fabric, and thereby 
further reduce frictional wear on the skin. The specific low friction 
porous fabric preferred for this invention is woven from PTFE coated 
material, such as the fabric woven from Teflon coated material and 
manufactured by W.L. Gore and Associates under the trademark Gortex. The 
coefficient of friction between PTFE and skin is approximately 0.04, which 
is less than 7% of the coefficient of friction betwen skin and cotton. 
Additionally, PTFE fabric is long lasting, flexible and has the required 
porous characteristics to enable an appropriate lubricant to flow 
therethrough. 
The PTFE fabric, although naturally smooth, is not naturally lubricated. 
Therefore to achieve the desired lubricating characteristics it is 
necessary to place a source of lubrication adjacent to the PTFE fabric. In 
most instances this source of lubricant will be a flexible sheet material 
that is impregnated with a lubricating ointment or cream. Many known 
ointments or creams would be acceptable, and it is desireable in certain 
instances to further incorporate an appropriate medicant into the 
lubricating ointment or cream. 
As noted above, a characteristic of any lubricant is that most wear that 
normally would occur on an adjacent surface will actually take place 
within the lubricant. Thus there is a gradual breakdown of the lubricating 
material. Additionally, to the extent that wear does occur on an adjacent 
surface, the sheared-off particles from the adjacent surface often are 
deposited in the lubricant. Furthermore, in the particular instance 
described above, part of the lubricant may be absorbed into or displaced 
by the skin disposed adjacent thereto. For the preceding reasons, it is 
important that the source of the lubricant be replaceable or 
replenishable. To ensure that the lubricant is not absorbed into the bed, 
wheel chair or other surface on which the patients weight is supported, it 
is preferred that an impervious sheet material be disposed between the 
source of lubricant and the bed, chair or other such structure. 
This specific structure for carrying out the subject invention preferably 
comprises a flexible porous PTFE fabric disposed adjacent the patient, a 
flexible lubricant-impregnated pad or mat disposed adjacent the PTFE 
fabric and a non-porous impervious sheet material disposed adjacent the 
lubricant impregnated pad but on the side thereof opposite the PTFE 
fabric. It is preferred that the structure be manufactured such that the 
lubricant impregnated pad can be removed periodically and either recharged 
with additional lubricant or replaced entirely. This structure can be 
manufactured to cover the entire supporting surface of the bed, chair or 
the like. However, as noted above, bed sores typically occur only adjacent 
areas of the body where a bony protrusion is disposed near the surface of 
the skin. In view of this predictable and localized occurrence of bed 
sores it is possible to make smaller composite pad structures which are 
affixed to the bed, chair or the like adjacent the areas of the patient 
where bed sores would be anticipated. 
In a preferred embodiment the low friction composite pad structure includes 
attachments which enable the pad to be affixed to the supporting structure 
in a replaceable but substantially stationary manner. For example in one 
particular embodiment, as explained and illustrated below, the bed pad 
includes a plurality of straps which can be wrapped around the supporting 
structure and connected to one another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The pad of the subject invention is indicated generally by the numeral 10 
in FIG. 1. The pad 10 is a composite structure which includes a pouch 
portion 12 into which a lubricated insert 14 is placed. The lubricated 
insert 14, as shown most clearly in FIG. 2, is a substantially rectangular 
piece of flexible sheet material which is impregnated with a lubricating 
ointment or cream. In addition to being impregnated with the lubricant, 
the insert 14 may also be treated with medications as appropriate. 
With reference to FIGS. 1 and 3, the insert 14 is dimensioned to fit 
entirely within the pouch 12. The pouch 12 is of generally rectangular 
planar configuration, and is formed from an upper layer 16 and a lower 
layer 18. More particularly, the upper layer 16 is a low friction porous 
sheet material which preferably is formed from a woven PTFE fabric. The 
PTFE fabric employed in the upper layer 16 preferably is woven Teflon 
coated fabric sold by W.L. Gore and Associates under the trademark Gortex. 
As noted above, this PTFE fabric has a coefficient of friction of 
approximately 0.04. Additionally the porous characteristics of the PTFE 
fabric from which the upper layer 16 is formed enables the lubricant of 
the insert 14 to permeate through the upper layer 16, thereby further 
reducing friction between the skin of the patient and the pad 10. The 
lower layer 18 of the pouch portion 12, as shown in FIGS. 3 and 4, is 
formed from an impervious flexible sheet material such as a plastic sheet 
or a woven fabric of plastic coated fibers. 
The upper and lower layers 16 and 18 are fixedly secured to one another 
along longitudinal seams 20 and 21. The longitudinal seams 20 and 21 may 
either be formed by stitches or in certain instances by heat sealing. The 
upper layer 16 has opposed ends 22 and 24. One of the ends 22 and 24 may 
either be stitched or heat sealed to the lower layer 18. However at least 
one end 22 or 24 is free of the lower layer 18 to define an opening which 
enables insertion or removal of the lubicated insert 14. With this 
particular construction, a closure device may be disposed adjacent an end 
22 or 24, as explained below without imposing any discomfort to a patient 
lying on the subject pad 10. 
The bed pad 10, as shown in FIGS. 1 and 3, further includes straps 32, 34, 
36 and 38 which are securely attached to the pouch 12. The straps 32 
through 38 are of sufficient length to be extended substantially around 
the structure on which the patient is supported. As shown in the FIG. 6, 
the straps 32 through 36 are provided with releasable fastening mechanism 
40 and 42 such as those sold under the trademark Velcro. 
In use, the pad 10 is securely mounted to a supporting structure such as a 
bed 44. More particularly, the straps 32, 34, 36 and 38 are respectively 
wrapped around the bed 44 or other supporting structure and are secured to 
one another at the fastening mechanisms 40 and 42. The pad 10 is 
positioned on the bed 44 to be substantially aligned with a portion of the 
patient's body which is particularly susceptible to bed sores. As 
illustrated in FIG. 5, for example, the pad 10 is positioned to be 
substantially in line with the buttocks portion of the patient. In some 
instances it may be desireable to employ more than one such pad, with 
other pads being positioned near the base of the skull, the rear portion 
of the heels, or the elbows. If the patient changes position, for example, 
from lying on his or her back to his or her front, the pad 10 can easily 
be repositioned on the bed 44 so as to be aligned with other areas of the 
body. 
As explained above, and as illustrated clearly in FIG. 5, the lower layer 
18, which is formed from an impervious sheet material is positioned 
against the surface of the bed 44. As a result of this positioning, the 
lubricant included in the lubricated insert 14 will not flow toward and be 
absorbed by the bed 44. Conversely, the upper layer 16 is formed from a 
porous material which readily allows the lubricant in the lubricated 
insert 14 to flow therethrough to further lubricate the interface between 
the patient and the surface on which he or she lies. Additionally, as 
explained above, the upper layer 16 is formed from a PTFE fabric which 
inheritantly has a very low coefficient of friction. Thus the combination 
of the low friction PTFE fabric from which the upper layer 16 is formed, 
and the ability of the lubricant from the lubricated insert 14 to flow 
through the upper layer 16 results in an extremely low coefficient of 
friction at the interface between the patient and the supporting surface. 
As explained in detail above, the low friction enabled by the subject bed 
pad 10 substantially prevents the onset of bed sores. 
FIGS. 5 and 6 also show the opening adjacent end 22 of top layer 16 in the 
pouch portion 12 which provides easy access to the lubricated insert 14 
for the periodic replacement of the lubricated insert 14. To ensure secure 
closure of this opening, releasable closure strips 28 and 30, preferably 
Velcro, are mounted on the upper and lower layers 16 and 18 respectively. 
Since the closure strips 28 and 30 are at the very edge of the bed, they 
will not discomfort the patient. 
In summary a composite pad is provided for substantially preventing bed 
sores. The pad includes an upper layer formed from a low friction porous 
material, a lower layer formed from an impervious sheet of flexible 
material and an insert impregnated with a lubricating ointment or cream to 
be placed between the upper and lower layers of the pad. Preferably the 
upper layers are formed from a porous PTFE fabric. In this construction, 
the pad is positioned on a bed or other supporting structure such that the 
upper layer is adjacent to the patient. The low friction characteristics 
of the upper layer substantially prevent the frictional wear and heat 
which are major contributing factors to the onset of bed sores. 
Additionally, the porous characteristics of the upper layer permits the 
flow of the lubricating cream or ointment to the area adjacent the skin of 
the patient, thereby further preventing bed sores. The bed pad includes 
straps or the like which enable the pad to be removably attached to the 
supporting structure. The pad is further constructed to enable periodic 
replacement of the lubricated insert. In use, the pad typically would be 
positioned strategically adjacent areas that are most succeptible to bed 
sores. However, larger sheets of the subject bed pad can be constructed to 
cover substantially an entire bed in accordance with the particular needs 
of the patient. Additionally, the subject structure can be incorporated 
into a clothing article to be worn by the patient. 
While the invention has been described and illustrated with respect to a 
preferred embodiment, it is understood that various modifications can be 
made therein without departing from the spirit of the subject invention 
which should be limited only by the scope of the appended claims.