Patent Publication Number: US-2013245517-A1

Title: Edema drainage seat cushion

Description:
TECHNICAL FIELD 
     The present invention is generally directed to a seat cushion. More particularly, the present invention is directed to a medical seat cushion for the purposes of reducing interstitial fluid and congested fibrotic tissue in persons with edema in the lower regions, e.g. thighs, knees, and buttocks. 
     BACKGROUND OF THE INVENTION 
     Chronic leg edema is often suffered by people who have medical conditions such as lymphedema, venous stasis, wounds, obesity, paresis and lipoedema. People with chronic leg edema struggle with functional mobility due to the weight of the leg, weakness of the muscles, and dependency to the sitting position throughout the day and night. When the body is sitting for most of the day, venous and lymphatic flow in the leg becomes sluggish and interstitial tissue becomes congested. A fibrotic ridge of tissue often forms on the posterior aspect of the distal thigh and behind the knee which may be accompanied by fibrotic and edematous lobules. 
     Further, individuals struggling with obesity often have a pannus consisting of a dense layer of fatty tissue in the lower abdominal area which constricts lymph flow through the inguinal lymph bed. In the seated position, the pannus compromises fibrosis resolution and fluid exchange through the inguinal lymph bed and deeper lymphatic trunks in the pelvis. The anatomical alternative of lymphatic fluid drainage in the obese and sedentary individual would be to the outer thighs, buttocks, and up to the lymph watershed of the waist. However, this pathway is also compromised for the individual in the seated position by the external pressures on the posterior and lateral pelvic fatty tissue and chair. The combination of congested tissue in the thigh, the fibrotic ridge on the posterior thigh, and lack of muscle movement creates unhealthy fluid exchange and furthers the pathology of the lower leg, including venous stasis, edema, lymphedema and wounds. 
     Contemporary designs of seat cushions are often aesthetic, supportive, and pressure relieving. Medical seating designs focus on relieving pressure from the spine, coccyx, skin, and boney prominences in the hips. The construction of medical cushions used to address lymph flow through the thigh and buttocks are not evident. Medical cushions provide support and decompression through constant force on the legs, but do not address fibrotic tissue reduction or directional fluid exchange. The distal aspect of current medical and non-medical seat cushions end under the thigh and knee. The ends of these cushions create an abrupt impression on the posterior thigh, most noted with individuals who rely on the seated position throughout the day. In many cases, this abrupt impression compromises circulation of the leg and creates a ridge of fibrotic tissue at the back of the thigh and knee. In advanced cases, this fibrotic ridge extends to the inner and outer aspects of the knee and thigh in the form of lobules. This fibrotic tissue decreases the effectiveness of an already compromised circulation and contributes to further pathology of the leg. 
     From the above, it is therefore seen that there exists a need in the art to overcome the deficiencies and limitations described herein and above. 
     SUMMARY OF THE INVENTION 
     The shortcomings of the prior art are overcome and additional advantages are provided through a seat cushion designed to compress and stretch interstitial tissue, reduce fibrotic tissue by means of thixotropic influence, and stimulate lymph vessel clearing by channeling interstitial fluid along the lymphatic pathways on the posterior and lateral aspect of the thigh and buttocks. 
     Lymphatic vessels, specifically the deeper lymphangions, rely on physical movement of the body to stimulate the smooth muscle layer on the surface of the vessel. Accordingly, it is an object of the invention to provide two-way stretching foam strips to stimulate the smooth muscle contraction of the lymphangions, thus forcing the contraction and clearing of these vessels in the direction of the lymphatic pathway, thereby creating an efficient exchange of interstitial fluid from the thighs to the trunk. 
     Applying varying pressure against the surface of the leg influences the thixotropic properties of fibrotic tissue. Interstitial fibrotic tissue becomes less viscous when subjected to a constant shear rate. Accordingly, it is another object of the present invention to reduce the viscosity of fibrotic interstitial fluid through the use of alternating surface pressures against the surface of the leg and buttocks. 
     A sedentary person may also have an abdominal pannus which compresses the inguinal lymph bed of the thigh. The healthy lymph pathway of the leg is from the foot to the inguinal lymph node bed with several vessels directed to the posterior and lateral thigh. Therefore, it is yet another object of the present invention to enhance interstitial fluid resorption of the leg by assisting the inguinal lymph bed, as well as reroute interstitial fluid away from the inguinal lymph bed when constricted and channel fluid flow to the posterior and lateral thigh and buttocks. 
     Lastly, but not limited hereto, it is an even further object of the present invention to incorporate a posterior knee extension pad to apply gentle pressure against the tissue where the seating surface ends, thereby reducing the formation of a fibrotic ridge on the posterior thigh. 
     Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. 
     The recitation herein of desirable objects which are met by various embodiments of the present invention is not meant to imply or suggest that any or all of these objects are present as essential features, either individually or collectively, in the most general embodiment of the present invention or in any of its more specific embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of practice, together with the further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which: 
         FIG. 1  is a top elevation view of the seat cushion; 
         FIG. 2  is a top elevation view of the seat cushion depicting the foam strips; 
         FIG. 2   b  is an isometric detail view illustrating the elements of the seat cushion; 
         FIG. 3  is a partially isometric and cross-sectional front view of the seat cushion illustrating the top and bottom covers enclosing the foam strips; 
         FIG. 4  is a partially isometric and cross-sectional side view of the seat cushion illustrating the top and bottom covers enclosing the foam strips; 
         FIG. 5   a  is a partially isometric and cross-sectional side view of the seat cushion in use with the posterior knee extension pad; and 
         FIG. 5   b  is a partially isometric and cross-sectional side view of the posterior knee extension pad. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 4  depict the seat cushion  100  in its preferred embodiment. As it came be seen in  FIG. 1  and  FIG. 2   a , the seat cushion  100  comprises two distinct foam strip portions. The first portion  115 ,  125  comprises substantially straight lines of foam strips  130 , while the foam strips  130  of the second portion  110  diverge from a centerpoint, such as centerpoint  120 , to substantially form a chevron pattern. The design pattern of the foam strips  130 , are positioned to channel interstitial fluid away from the dorsolateral and dorsomedial territory of the thigh to the lymphatic capillary network on the lateral border of the thigh and lower lymph quadrant of the trunk. 
       FIGS. 2   b ,  3 , and  4  further illustrate the preferred elemental embodiments of the seat cushion  100 . As shown in the detailed view of  FIG. 2   b , a top cover  135  and a bottom cover  105  encapsulate the foam strips  130 . The foam strips  130  are preferably fabricated of a latex free material. The top cover  135  and bottom cover  105  are fabricated preferably of a breathable open celled polyurethane fabric. For reasons of safety, the foam strips  130 , top cover  135 , and bottom cover  105  are fabricated preferably with a fire retardant compound. 
     As shown in  FIG. 2   b , foam strip stitching  155  is placed around the perimeter of each individual foam strip  130 , and joins the bottom cover  105  to the top cover  135 . This foam strip stitching  155  helps each individual foam strip  130  maintain its respective position as part of the patterns defined by the first portion  115 ,  125  and second portion  110 . 
     As further illustrated in the cross-sectional view of  FIG. 3 , perimeter stitching  160  is placed around the outer edge of the seat cushion  100  to fasten the bottom cover  105  to the top cover  135 . Further channel stitching  165  is placed on each side of the foam strips  130 . Channel stitching  165  penetrates both the bottom cover  105  and top cover  135  to further secure respective covers to each other and creates individual channel pockets for each individual foam strip  130 . 
     The cross-sectional view of  FIG. 3  further illustrates that the preferred embodiment of seat cushion  100  comprises the foam strips  130  substantially spanning across the entire width of the seat cushion  100 . It can also be seen that the first portion  115 ,  125  and second portion  110  are substantially mirrored about a centerline through centerpoint  120 , which also divides seat cushion&#39;s  100  width into substantially equal halves. In this preferred embodiment, the foam strip  130  in the first portion  115 ,  125  is placed approximately 1.0 inch on center, while the first foam strip  130  in the second portion  110  is secured on a diagonal approximately 1.5 inches apart. Each foam strip  130  has an average width, in cross-section, approximately 0.5 inches and an average height, in cross-section, approximately 0.25 inches. 
     In accordance with the preferred embodiment,  FIG. 4  illustrates that in use, the front edge of the seat cushion  100  extends down the front edge of the seat surface. It has been found that this embodiment aids in reducing the fibrotic ridge formed behind a person&#39;s lower thigh and knee region, which is created by prolonged exposure to the pressure of a seat surface&#39;s front edge. 
     As further shown in  FIG. 5   a , an alternative embodiment to the seat cushion  100  incorporates a posterior knee extension pad  140 . In this manner, the seat cushion  100  provides the maximum reduction to the fibrotic ridge and maximum resistance to the creation of the fibrotic ridge formed behind a person&#39;s lower thigh and knee region by applying gentle pressure against the tissue where the seat surface ends. The knee extension pad  140  is placed between the seat surface and the front edge of the bottom cover  105  behind a person&#39;s knee. The knee extension pad  140  extends the entire width of the seat cushion  100 , and as shown in  FIG. 5   b , comprises dense foam  145  enclosed by a covering fabric  150 . The covering fabric  150  secures the dense foam  145  via knee extension pad stitching  170  located around the perimeter of the knee extension pad  140 . The dense foam  145  comprises material properties that are substantially of the same foam used for the foam strips  130 , while the covering fabric  150  comprises substantially of the same breathable open celled polyurethane fabric used for the top cover  135  and bottom cover  105 . 
     While the invention has been described in detail herein in accordance with certain preferred embodiments thereof, many modifications and changes therein may be effected by those skilled in the art. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the spirit and scope of the invention.