Patent Application
20200037779
The present disclosure relates to an area support surface having a mode of operation to optimize conditions to avoid interrupting the healing of pressure injuries in the area of the buttocks while an individual is placed in the seated position through control of individual cells within the support surface to modulate external pressure over time on different regions of the buttocks. The area support surface also provides through its operation a means to restrain the progress of spinal deformities.
External pressure applied to bony parts of the human body may disrupt the blood flow through the capillaries and, when prolonged, may lead to the formation of pressure injuries. Generally, the higher the external pressure applied to the capillaries against bony parts of the body, the shorter the time required for a pressure sore to develop. Individuals with mobility impairments that prevent independent repositioning are at the highest risk for developing pressure ulcers.
Healthy people with good motor skills and sensory abilities instinctively move and shift weight while seated or lying in bed, and do so even while asleep. Such movements prevent prolonged application of pressure to any one site on the individual's body. People with poor motor skills and sensitivity disorders, such as the frail elderly and people with severe disabilities may not be able to sense pain or perform frequent weight relief essential for disrupting the capillary occlusion that leads to the creation of pressure sores without the assistance of another person.
It is commonly accepted among scholars and investigators that 32 mmHg is the threshold for capillary pressure. Higher external pressure over bony parts of the body may cause interruption of the blood supply to the correspondent cells resulting in loss of circulation and tissue necrosis. Early studies teach that certain parts of the body, such as the coccyx (tail bone) can bear much lower external pressure before breakdown of the skin. Aging and illness may reduce significantly the threshold of 32 mmHg.
Prolonged bed rest carries medical risks that affect cardiovascular, hematological and respiratory systems and have negative impact on the muscular and skeletal systems of the human body. Upright position during part of the day is essential for the human being. The seated position, however, raises several difficulties that are unique to problems caused by an immobile patient in the supine position.
While hospital mattresses and wheelchair cushions are both classified as support surfaces, there is a vast dissimilarity between them. The mattress, which may be referred to as a “full support surface,” covers approximately 1,800 square inches. A standard wheelchair cushion measuring 16 inches×18 inches, which may be referred to as an “area support surface,” covers 288 square inches. As a result, such a standard wheelchair cushion provides about 16% of the support area as a mattress to support approximately 70% of the body's weight in the seated position. Thus, the average pressure applied at each point of the cushion will often be 4 to 5 times higher than the pressure applied by the body on a mattress. Furthermore, while the standard hospital mattress is at least 5 inches deep (i.e., thickness), the wheelchair cushion is limited to 3 inches deep at the most. In the instance of a powered cushion, this depth allows 2.5 inch high air cells. These conditions create a high risk of bottoming out in the seated position on area support surfaces, which is a minimal or non-existent risk in full support surfaces.
The seated position as opposed to the supine position presents yet another set of particular problems needed to be addressed. The two ischials are 1.5 inches lower than the femurs and as long as no action is taken, they bear the entire pressure created by the upper body in the seated position. Since this position creates a very unstable situation for the already frail body supported by the cushion, maintaining sidewise equilibrium is of utmost importance in the seated position. Also, if the body slides forward, then the coccyx becomes the third bony part of support at very high risk of formation of pressure injury.
Thus, the risk of developing pressure sore at an ischial tuberosity or coccyx site while seated is much higher than developing a pressure injury anywhere else in the body in the supine position. And because of the issues discussed above, providing assistance for the healing process of pressure injuries in the buttocks area while in the seated position is much more complex than in the supine position. This likely explains why during the last decade hundreds of “seating and positioning” clinics emerged throughout the country, most of them attached to hospitals, specializing in solving problems related to pressure injuries in the buttocks area.
A study published in Europe in 2011 teaches that the average distance between the ischial tuberosities is 12.4 cm (4.88 inches), the minimum distance measured is 9.5 cm (3.74 inches) and the maximum is 15.5 cm (6.1 inches). The distance variation between the ischials is an important factor to be taken in consideration when planning the removal or reduction of the interface pressure from the sites of the ischials tuberosities. Similar consideration should be given to the possibility of a frail seated patient with an open wound in the coccyx, sliding forward from his/her original position.
The most important factor in the development of a pressure ulcer is unrelieved pressure. Therefore, a crucial requirement for the healing of an existing pressure injury is the complete removal of pressure at the site of the sore or, at least reduction of the interface pressure to under the threshold for capillary pressure for as long as the duration of the healing of the wound is not thoroughly completed. Scholars and investigators agree that pressure injuries are caused primarily by pressure and are treated with pressure removal. Thus, the very first step in treating a pressure sore at any stage is removing or relieving the pressure that caused it. Cyclical pressure on an existing injury caused by alternating pressure systems support system holds back the healing process of the open wound and should be avoided by all means.
Cyclical pressure on an existing injury caused by alternating pressure systems holds back the healing process of the open wound and should be avoided by an individual with open wounds in the sacrum/coccyx or ischia area when seated in a chair or a wheelchair.
Passive cushions now being used in the market utilizing foam, gel, air pockets or contour cushions may reduce the pressure on the bony parts of the buttocks but are unable to eliminate the pressure or lower it below the threshold for capillary pressure. Passive cushions provide comfort but do not prevent the creation of pressure sores nor do they remove the pressure from the site of an existing pressure sore enough for continuous healing. Independent studies show that best passive cushions reduce capillary pressure to around 60 mmHg (or higher). Long periods of low pressure are equally as damaging to the skin as short periods of high pressure. That is why individuals at risk seated on passive cushions are required to perform “lifts-and-shifts” frequently. Pressure relief movements while seated, however, require good upper-limb strength, which is often absent in the frail elderly and the physically disabled at high risk for developing pressure sores.
Existing systems for powered area support surfaces, and more particular regarding wheelchair cushions, often teach the use of an alternating pressure method of operation. One single exception is U.S. Pat. No. 6,560,803 (Zur) that teaches the control of individual air cells for the prevention of pressure sores formation. Most, but not all, of these alternating pressure wheelchair cushions use long, lateral, tubing types of air compartments divided in two groups: one group composed of interconnected odd cells, the other composed of the interconnected even cells. Some systems replace the lateral tubing with multiple, vertically placed air cells, but in both cases, the tubes or the air cells are divided in two interconnected groups operating in unison- one group inflates while the other group deflates. If properly deflated to a level that the applied pressure is less than the capillaries pressure, the person seated would actually be supported by only half of the cushion surface and the interface pressure, already very high in the seated position, would double, causing discomfort and a very high risk for skin breakdown. For this reason, alternating pressure systems avoid complete deflation that would separate the deflated compartments from the body seated on the cushion and the pressure at the bony parts of the buttocks remains higher than the capillary pressure. For the healing of existing pressure sores, alternating pressure methods also has negative effect on the healing process by the constant cyclical increase and decrease of pressure they apply on the wound.
Avoiding the interruption of the healing process of existing pressure injuries and actually assisting in the healing process may be achieved by:
For healing an existing pressure injury, the removal alone of pressure below the open wound is, in effect, forbidden by professionals and by NPUAP and the European and Pacific international institutes. It creates the “donut effect” which generates friction and sheer forces, the second most important factors for skin breakdown and formation of pressure injuries. Minimizing the donut effect requires the control of the inner pressure in the individual cells circa the deflated cell, the gradual increase of inner pressure in the second and third rounds of cells and the measuring and reflection of the pressure on the controller's screen for the clinician to make corrections as needed.
Unlike pressure injuries which might be life threatening, spinal misalignment cause, in most cases, pain and breathing problems but are not life endangering. It is estimated that about 7 million Americans suffer from spinal abnormalities. Tall and thin girls aged 8 to 14 comprise the majority of early stage scoliosis cases. The risk of progression increases dramatically as the curvature of the spine is higher but it stops as skeletal maturity is reached. The only effective treatment offered are back braces for children prior to maturity and spine surgery.
People confined to wheelchairs often are left for long periods of time without routine check-ups by clinicians until a pressure injury stage 1 or 2 develops on their buttocks. Early stages of pressure injury lead to more severe cases and close follow-up on high risk patients is essential. This is where telemedicine may be of great service to the individuals and the health system.
Accordingly, a new and useful system that creates optimal conditions for continuous healing existing pressure ulcers in the buttocks area while an individual is in the seated position, and that may assist people with spinal abnormalities to alleviate pain and breathing problems, is desired
The present disclosure describes an area support surface seating system suitable to provide localized external pressure relief for seated user that employs a pneumatic, computer controlled area support surface having a plurality of independent, vertically mounted inflatable air cells. A power supply system that includes a selector valve is operatively connected to the plurality of cells through the selector valve. The supply system also includes as control circuitry a printed circuit board (“PCB”) with a pressure sensor and a micro-processor in communication with a wireless control device. A Bluetooth low energy interface may be employed to facilitate communication between supply system and the wireless control device.
The area support surface of the system has a cushion base with a low elevation surface upon which the plurality of independent air cells is mounted. A grid of tubes located under the low elevation connects each air cell to the selector valve in the supply system. A second, higher elevation on the cushion base contains the supply system. The supply system, which also includes a compressor and a rechargeable battery as a power source, operates to selectively inflate and deflate either a single air cell or a group of air cells. A flash memory chip may be installed on the PCB so as to allow the computer controlled area support surface seating system to collect, store and send the data for printing or analysis by the clinician to ascertain the treatment designed for the patient.
The wireless control device, which may be a smartphone or other tablet, provides a user control interface that allows for a user to selectively adjust the internal pressure to each individual air cell. The wireless control device, continually retrieves data from the pressure sensor and displays upon request a mapping of the internal pressure for each individual air cell in the support surface. Accordingly, the wireless control device allows a clinician to address each individual air cell in order to determine its level of inflation and the duration of deflation.
It is an object of the present invention to eliminate or reduce the interface pressure to under the capillary pressure at the site of an open (or pressure related) wound and to provide an ability to control the pressure in each one of the air cells in vicinity to the deflated cell and thus minimize the effect of friction and shear force on the wound.
It is another object of the present invention to compensate for the loss of equilibrium caused by misalignment of the spinal cord by disproportionally inflation of the right and left sides of the area support surface, thus controlling the progression of the spinal cord misalignment at early ages and alleviating pain at later ages
It is another object of the present invention to maintain a constant exchange of information, to provide feedback between the pressure sensor and an external controller, and to display the result on the screen of the controller, so as to enable the collection, storage, and transmission of such the data to the clinician by means of remote communication.
These and other objects and advantages will be apparent to one of skill in the alt
Applicant's area support surface seating system described herein provides for localized pressure relief for seated user in the form of a cushion for a wheelchair or other support for a seated user. The area support surface seating system is capable of optimizing conditions for a seated user to avoid interrupting the healing of pressure injuries in the area of the buttocks as well as to restrain the progress of spinal deformities while the user is in the seated position.
Referring now to the drawings and, in particular, to
As illustrated in
The cushion base 13 is built with a lower ledge 16 on all four sides of the base, as shown in
The inflatable air cells 10 are made of light, soft, non-stretchable fabric. A ring of ABS or similar material may be placed and sealed inside the cell at the bottom to prevent the cell from ballooning when fully inflated. Each air cell 10 has an opening in the bottom in which a rubber or plastic fitting is inserted and sealed to the fabric of the cell 10. The fittings at the bottom of the respective cells 10 extend through holes 55 in base 13 to connect each respective cell 10 to the corresponding respective tube 64 from the selector valve 32. The grid of tubes 64 connecting the selector valve 32 to each individual air cell 10 is placed under the matrix of air cells 10 in the space of the low elevation 15.
In some embodiments of the present invention, the size, shape and amount of air cells in the support surface of the seating system may be of varying sizes and shapes in effort to promote healing in accordance with the method described below, including but not limited to round cells 10, specifically positioned oval cells 11 or specifically positioned rectangular cells 12, shown in
The most common location in the buttock area for the formation of pressure injuries are the ischial tuberosities. As previously mentioned, the average distance between the two ischial tuberosities. is 12.4 cm (4.88″). The size of cells 10 in the preferred embodiment is calculated to correspond to the most common distance between the ischial tuberosities.
The coccyx (tail bone) is another common spot for the formation of pressure sores. Frail people tend to slide down in their seat. Thus, if the individual treated has an open wound or is at a very high risk of developing a pressure injury at the coccyx location, oval cells or rectangular cells might be used as shown in
The pneumatic supply system, as shown in
It is contemplated that the compressor 31 may be an off-the-shelf item. Consideration is given to the size, power, noise and vibration, quality and price. In some embodiments, if the noise or vibration is too high, the compressor 31 may be located outside of the cushion base 13 in a separate case, with improved sound barrier, connected to the rest of the system by quick connectors.
It is contemplated that the pressure sensor 33 and the selector valve 32 may also be off-the-shelf items. The selector valve 32 will have plurality of channels to provide the best and most cost-effective results of the treatment. A tube 64 may provide pressurized air to a single air cell 10 and/or two or more air cells 10. For each channel, the selector valve 32 has three positions: open to receive air to the selected air cell; open to release air from the air cell to the atmosphere; and closed to maintain the pressure state of the selected cell. The opening and closing of the selector valve 32 channels, as well as the operation of the compressor 31 and pressure sensor 33 and the order and sequence of the operation is directed by the microprocessor 25.
The PCB 22 has a connector 26 to the compressor 31; a connector 27 to the selector valve 32; a connector 28 to the battery 23; a connector 29 to the speaker 18 that provides an audio alarm signaling that a bottoming out condition has occurred and a connector 30 to the speaker 19 that audio signals when any parameter of operation (such as inflation level of an air cell or duration of an air cell deflation prior to an automatic change) is set or changed. The PCB 22 also has the pressure sensor 33 and the microprocessor 25.
The microprocessor 25 may be an off-the-shelf item encoded to communicate with the wireless control device 40, receive the information pre-set by the clinician in the wireless control device 40 and execute the program coordinating the operation of the supply system elements.
When a channel in the selector valve 32 is in the position open for air flow to cell 10, the pressure sensor 33 measures the combined pressure in tube 66 and the respective cell or group of cells 10 that are associated with the open channel. As the pressure reaches the level preset in the program, the pressure sensor 33 signals the microprocessor 25 which in turn signals to the selector valve 32 to switch this channel to the close position and signals the compressor 31 to cease pumping air. At the same time, the microprocessor 25 signals the selector valve 32 to open another channel to release air from its respective cell 10 or group of cells 10 to the atmosphere. As long as this line is open for the release of air to the atmosphere, there is no resistance in this line and therefore pressure does not build up in the cell or group of cells associated with this channel. After a preset duration of time, the micro-processor 25 signals the selector valve 32 to turn this line to the position of re-inflation (open for air flow to the cell), signals the compressor 31 to pump air and the selector valve 32 to open another line for deflation. The cycle continues according to the program set by the clinician using the external wireless control device 40.
In another embodiment of the present invention, the supply system is located in a separate case outside the cushion with a quick connector for the air supply system and another quick connector for the electrical system. In another embodiment of the present invention the air pump alone is located in a separate case outside the cushion with air supply and electrical quick connectors. In another embodiment of the present invention where there is enough space under the plurality of air cells such as in a bedside chair, or a home or office chair, the base is uniformly elevated to be covered on its entire surface with air cells 10 and all the elements of the supply system 20 are placed underneath the layer of air cells along with the grid of tubing 64. Other embodiments of the present invention where a larger cushion is required, such as chairs and wheelchairs for obese people, the support surface may be comprised of larger cells 10 or an increased number of cells 10.
The area support surface system may be operated and controlled using an external wireless control device 40 that uses Bluetooth low energy connectivity, such as a smart phone or a tablet. As illustrated in
The inflation pressure can be selected in intervals most desirable by the clinicians. In the preferred embodiment of the present invention the inflation pressure is selected in intervals of 0.25 PSI for all cells or groups of cells in the area support surface, by pointing to the cell on the screen 46, moving the slider 43 to the selected level of inflation and pressing the set button 48 when done. The duration of the deflation can be set between 1 and any number of seconds when touching window 44, using the slider to choose the desired figure and pressing the set window 48.
A software application for operating the area support surface system may be embedded in the micro-processor 25. An operator may use the wireless control device 40 to choose the features most suitable to the patient treated and conveys them to the micro-processor 25. The micro-processor processes the new data and transmits operating parameters to the various components of the supply system 20, including the compressor 31, the selector valve 32 and the pressure sensor 33.
Those skilled in the art will also appreciate the ability of the system to create higher pressure in one side and lower pressure in the other side of the support surface in order to compensate for the pressure produced by the spine misalignment, especially by individuals with C curvature in their spine. Taking this preventive measure at early stage of spinal deformity during school time and homework at home, might reduce the chance of progression of a curvature that exceeds 20 degrees at the risky age from 68 percent to a much lower level.
As illustrated in
Referring now to
In the case of an existing pressure sore at the ischial tuberosity on the right side of a seated user, air cell B2 that corresponds to the right ischial tuberosities of the seated person is set to zero and cell B4 is set for minimal inflation of 1 PSI. In the rare case of existing pressure sores on both sides of the ischial tuberosities, cells B2 and B4 would both be set for zero. The inflation level of the remaining cells may have to be increased or decreased to avoid bottoming out, depending on the size and the weight of the individual being treated.
The relative pressure of each cell 10 is displayed with a number; in example being one of substantially 0, 1, 1.5, 2, and 2.5 PSI in a preferred non-limiting example. In an embodiment, the maximum air pressure allowed at any cell 10 may be 2.5 PSI. But in actuality, maximum pressure is limited only by the manufacturing tolerances of the materials of cell 10. Relatively lower pressures of 1 and 1.5 PSI are adjacent to the zero-pressure cell 10, and pressure is gradually increased as the cells 10 are farther away from the sore and the corresponding zero pressure cell 10. This provides a gradual interface pressure gradient from a target location of the zero-pressure cell 10 for reducing friction and shear forces applied to the skin of the buttocks of the individual seated on the cushion.
By utilizing a cushion constructed in accordance with the present invention, it becomes possible to selectively address individual inflatable cells within the array of cells to create an area at a target location which may be free of interface pressure at the site of an open wound on the buttocks, thus setting up the conditions for not tampering with the healing process of the wound. As a result of the unique structure of the present invention, the damaging intermittent pressure on a wound, which is a result of the prior art devices, may be eliminated. Because of the ability to embed a variety of patterns for individually addressed cells, it is possible to provide constant low pressure at a wound site, to avoid exceeding a desired healing pressure. Furthermore, optimum conditions may be created by an accredited user for faster healing of an open wound on the buttocks by providing a no pressure area under the wound while the rest of the support surface consisted of the remaining cells 10 performs a preventive protocol to avoid the development of new pressure sores.
Furthermore by providing an array of independent air cells, the resulting structure allows for the control of inflation and deflation of one cell at a time or a group of cells acting together at a time or both. In an embodiment, two of the active (non-deflated) cells may be inflated/deflated at a time, one on each side of the buttocks, for the purpose of maintaining equilibrium of the body seated. Deflating two out of, for example, twenty cell support surface makes very little difference, if at all, in comfort or in the increase of inner pressure required in the inflated cells. Furthermore, because the cells are operated independently, a zero-interface pressure can be produced at more than one location within the cushion if necessary to help heal more wounds. At the same time, even if no sores are present, the remaining area of cushion may operate in the prevention mode.
The system described herein also allows the clinician to personalize the preventive protocol to compensate for the persons weight and the severity of the risk for pressure sores. It allows the clinician to choose the rate of inflation between 1.5, 2 and 2.5 PSI and the duration of rest in the deflation mode from 0 seconds to any number.
Attaining a zero-interface pressure area between the cushion air cell and the sore under the open wound results in:
The function of the support surface is controlled by the clinician using an electronic device such as a smart phone, a tablet or a handheld computer. It allows to:
The ability to control the present invention through a smartphone or a tablet, with the wireless communication and the constant exchange of information and feedback between the pressure sensor, the microchip and the external controller, enable area support surface system in accordance with the present disclosure to be ready to be used for telemedicine, thus saving resources for the patients, providers and the entire medical system.
It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.
