Inflation level monitoring system for inflatable cushions

A monitoring system for monitoring inflation pressure within an inflatable cushion. The monitoring system includes a housing, a pneumatic tube, a locking adaptor and a sensing and signaling system. The pneumatic tube extends through the housing with the locking adaptor attached to the distal end of the pneumatic tube. The locking adaptor is effective for releasably and sealingly attaching the pneumatic tube to a stem valve on an inflatable cushion. The sensing and signaling is retained within the housing and includes at least a pressure sensor in pneumatic communication with the pneumatic tube proximate a proximal end of the pneumatic tube, and a means in communication with the pressure sensor for generating a perceptible signal when the pressure sensed by the pressure sensor falls below a predetermined threshold value.

FIELD OF THE INVENTION

The invention relates to systems for monitoring inflation pressure in inflatable cushions.

BACKGROUND

Patients confined to wheelchairs face the prospect of developing decubitus ulcers or “bed sores” on their buttocks. These ulcers form at bony locations when prolonged sitting pressure reduces blood circulation below the level required to sustain tissue life. Skin breakdown can also occur when the patient is seated on a wheelchair cushion that does not provide adequate ventilation and causes the skin to remain excessively moist and warm for protracted periods. A healthy subject seated for a prolonged period in a single position will sense discomfort and eventually pain from the reduced blood circulation, and will change positions. However, if the patient is paralyzed, disoriented, sick or otherwise disabled, they may be unaware of the discomfort or pain, or may be unable to change position.

Various wheelchair cushions are commercially available for reducing the risk of developing “bed sores” by spreading the person's weight over as much area as possible. Such cushions include inflatable cushions, fluid-filled cushions, gel filled cushions, foam cushions and combinations thereof. As a general matter, gel-filled and foam cushions provide a soft surface but do little to reduce pressure exerted upon the bony regions of the buttock and contribute to moisture and heat build up. Fluid filled cushions (e.g., cushions filled with water) help reduce the pressure exerted upon the bony regions of the buttock, but are heavy and subject to leaking of the fluid. Inflatable cushions (e.g., cushions filled with pressurized air) are lightweight and help reduce the pressure exerted upon the bony regions of the buttock. However, inflatable cushions are also subject to leaking, with a resultant loss in effectiveness and eventual “bottoming out” of the person seated on the cushion (i.e., direct contact between the person and the seat of the chair). Failure to reinflate the cushion to the proper pressure for an extended period of time can eventually lead to the development of “bed sores”.

Cushion inflation monitoring systems are known, such as the system described in U.S. Pat. No. 5,487,197. However, such inflation monitoring systems are customized for use with a particular type and style of cushion. Persons confined to wheelchairs spend a significant portion of the day seated in the wheelchair, and are understandably sensitive to selecting just the right cushion.

Hence, a need exists for an inflation monitoring system which can monitor the inflation pressure in a wide variety of inflatable cushions so as to provide persons with the benefit of an inflation pressure monitor in connection with a wider range of cushion types and styles.

SUMMARY OF THE INVENTION

A monitoring system for monitoring inflation pressure within an inflatable cushion. The monitoring system includes a housing, a pneumatic tube, a locking adaptor and a sensing and signaling system. The pneumatic tube extends through the housing with the locking adaptor attached to the distal end of the pneumatic tube. The locking adaptor is effective for releasably and sealingly attaching the pneumatic tube to a stem valve on an inflatable cushion. The sensing and signaling system is retained within the housing and includes at least a pressure sensor im pneumatic communication with the pneumatic tube proximate a proximal end of the pneumatic tube, and a means in communication with the pressure sensor for generating a perceptible signal when the pressure sensed by the pressure sensor falls below a predetermined threshold value.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Nomenclature

Referring generally toFIG. 1, the invention is a monitoring system10for monitoring inflation pressure within an inflatable cushion100. The embodiment of the monitoring system10shown inFIGS. 1 and 2includes a housing20, a sleeve30, a pneumatic tube40, a locking adaptor50, a sensing and signaling system60, a pump70and a relief valve80.

As illustrated schematically inFIG. 2, the sensing and signaling system60includes a microprocessor61, a pressure sensor62, a means for generating a perceptible signal, and a power source (e.g., a battery67). The pressure sensor62is in fluid communication with a tube40for sensing inflation pressure within the cushion100and in electrical communication with the microprocessor61for transmitting a signal indicative of the sensed inflation pressure. The microprocessor61is programmed to compare the sensed inflation pressure with a threshold value and generate a perceptible signal (e.g., red light, beep and/or vibration) when the sensed inflation pressure falls below the threshold value. Alternatively, a pressure switch (not shown) or a pressure transducer (not shown) may be substituted for the microprocessor61, with a preference for a plurality of pressure switches each in fluid communication with the tube40and effective for generating a unique perceptible signal at different sensed pressures (e.g., a first pressure switch (not shown) remains closed so long as the sensed pressure is above a first threshold pressure value and thereby activates a first green LED63so long as the inflation pressure remains above the first threshold value, a second pressure switch (not shown) remains closed so long as the sensed pressure is above a second threshold pressure value—which is lower than the first threshold pressure value—and thereby activates a second green LED63so long as the inflation pressure remains above the second threshold value, a third pressure switch (not shown) remains closed so long as the sensed pressure is above a third threshold pressure value which is lower than the first and second threshold pressure values—and thereby activates a third green LED63so long as the inflation pressure remains above the second threshold value, and a fourth pressure switch (not shown) set to close at a fourth threshold pressure value—which is lower than the first, second and third threshold pressure values—and thereby activates a red LED63only when the inflation pressure decreases below the fourth and final threshold value.)

Various means for generating a perceptible signal are shown inFIG. 1, including an LED63for providing a visual signal, a speaker64for providing an audible signal, and a vibrator65for providing a tactile signal. As shown inFIG. 1, a preferred perceptible signal is a series of LEDs63with the LEDs63sequentially switched ON by the microprocessor61as the inflation pressure decreases. By way of non-limiting example, a green LED63remains ON until the inflation pressure decreases below a first threshold value, at which time the green LED63is turned OFF and a yellow LED63is turned ON. If inflation pressure continues to decrease below a second threshold value, the yellow LED63is turned OFF and an orange LED63is turned ON. Finally, if inflation pressure continues to decrease below a third and final threshold value, the orange LED63is turned OFF and a red LED63is turned ON.

As shown inFIG. 1, the sensing and signaling system60is preferably housed in a weather resistant protective housing20. Housing20is preferably constructed from metal or plastic and retained within a sleeve30having a means for mounting the housing20to a wheelchair (not shown). Housing20is preferably less than 40 in3in size, most preferably less than 20 in3in size, to facilitate attachment to the frame of a wheelchair in a convenient location. The mounting means may be selected from any of the well known means for attaching such items to a frame (not shown), including metal fittings, metal clips, tie straps, twist straps, male/female snaps, hook and loop tape, etc. As shown inFIG. 1, a preferred mounting means is a pair of hook and loop straps31.

Flexible tubing40extends through the housing20with a proximal end40ppositioned within the housing20for communication with the pressure sensor62. A locking adaptor50is sealingly attached to the distal end40dof the flexible tubing40. Locking adaptor50is effective for releasably and sealingly securing the flexible tubing40to a valve stem110on an inflatable cushion100. One embodiment of an acceptable locking adaptor50, shown inFIG. 1, includes a lever (unnumbered) pivotable between a clamping position and a release position. An alternative embodiment, not shown, is for the distal end40dof the tube40to be sized relative to the stem110such that the tube40can be friction fitted over the stem110. The tube40can then optionally be secured onto the stem110by a cable tie (not shown) or other suitable clamping mechanism. Other embodiments for securing the tube40to the stem110are known to those skilled in the art and can also be employed.