A permanent magnet housed in a porous metal container is implanted in the pelvis of a subject and a second permanent magnet is attached to a supporting structure, such as the seat of a wheelchair. The opposing force produced by the two magnets when the subject rests on the supporting structure reduces the compressive force acting on the tissues therebetween.

An fluid channeling system that comprises a series of elongated chambers having a rectangular cross section. Each of these chambers is disposed adjacent to the other and extends parallel to the other in either a single layer configuration or a two layer configuration. There is at least one fluid such as air, helium, or an air helium combination disposed within these chambers. The fluid enters these chambers through at least one fluid intake valve which is in fluid communication with these chambers. Helium has particular properties that make it conducive for this type of an application. Helium is odorless, colorless, and tasteless, in addition, Helium can diffuse through many materials commonly used in laboratories such as rubber and PVC. Therefore, if the present invention uses Helium, the materials used in creating this device must reflect these properties. There is also at least one fluid conveyor such as a series of pipes or a series of pipes and a manifold wherein the fluid conveyor conveys the fluid between alternating chambers in the series of chambers. These chambers may also contain a resilient material such as a polyurethane foam that is porous to the fluid. As a load is a applied to the chambers, the chambers alternately compress or expand causing fluid to flow in through the intake valves and into the chambers. The fluid stops flowing into the chambers when the pressure inside the chambers balance with the pressure outside the chambers.

An air cushion with selectively deflated chambers has a base, multiple air pouches, multiple attachment devices, at least two air tubes, an air pump and a cover sheet. The air pouches are mounted on the base, and each air pouch has an inner space and multiple compression straps. The inner space is divided into multiple chambers that communicate with each other. Each compression strap keeps a selected chamber of the air pouches from inflating. The attachment devices are mounted on the base to attach the air pouches to the base. The at least two air tubes connect to the air pouches and communicates with the inner spaces of the air pouches. The air pump connects to and pumps air through the air tubes into the air pouches. Any one of the chambers can be kept from inflating if the chamber contacts injured skin of a patient.

A pressure pad has two sets of cells with a sensor pad positioned under the pad. During inflation, part of the flow goes to the sensor pad to exhaust and the rest fills the cells. Any change in patient position/weight causing a change in airflow in tube will alter the differential pressure measured at a pressure transducer. Based on this feedback a microprocessor directly controls the power level to the pump, thus adjusting the airflow to the cells to prevent bottoming or to rung at a minimum pressure. The pressure pad is segmented into a heel section, upper leg section, torso section, and a head section. The heel, head, and upper leg sections are maintained at a lower pressure, and the torso section at a higher pressure. A control module to control the flow in the segments is provided inside the pressure pad. The pressure pad can be an alternating or static pad.

A support surface 10 includes a series of inflatable cells 30, 40 inflated alternately by a compressor 11. The cells 30, 40 are exhausted via an exhaust port 50 having a restrictor 60 of known diameter. A pressure transducer 70 measures the cell 30, 40 pressure. Some of the cells 30, 40 during their deflating/inflating cycle are exhausted through the exhaust port 50 and the cell pressure decay over a time is monitored. A microprocessor calculates the mathematical function related to the cell pressure decay with time, compares the value with compiled data and adjusts the output of the compressor accordingly. The sequence of exhausting via a port 50 is repeated at every inflation/deflation cycle and the pressure decay monitored and compared with the known data and the compressor output adjusted automatically to provide a new operating pressure. Therefore, any change in the person's position, e.g., supine, to side or sitting are accommodated by the cell pressure automatically being adjusted to prevent bottoming or high interface pressures.