Warning mat to signal air seat cushion failure

A warning mat that signals partial or total deflation of a pneumatic wheelchair cushion has been developed. The purpose of this device is to prevent pressure sores that occur when an inflatable seat cushion loses air gradually and causes ischial tuberosities of a spinal cord injured patient to "bottom out," ie, to come to rest on the hard wheelchair seat. Resulting ischemic necrosis in this anesthetized area is prevented when localized high seating pressure triggers a pressure sensitive warning mat under the wheelchair cushion to produce a high-pitched audio signal warning the patient to reinflate the cushion or leave the chair. Efficacy of this device has been demonstrated in clinical trials, but prevention of decubiti will need to be substantiated by a long-term controlled study.