Monitoring the relief of pressure points for pressure ulcer prevention: A subject dependent approach

Pressure ulcers are of great cost to both the patient and the healthcare system. Devices have been developed with the goal of pressure ulcer prevention, but many available technically complex devices have been shown to be no more effective than low pressure overlays or mattresses. This paper proposes a subject dependent algorithm capable of automatically detecting when and where pressure points have been relieved from underneath a supine subject, without any user inputs or assumptions. Pressure sensitive mats, associated software, a laptop and a video camera were used to measure and collect pressure signals generated by a supine subject performing 3 movements: the subject rolling to one side of the body, then to the other side, and the subject attempting to roll without lifting any pressure points off the mattress. The data was zeroed, baseline values were found, differences in sensor score from baseline were calculated, and instances during which a valley on one side coincided with a peak on the other, were recorded. Examination of these results indicated that the algorithm was capable of determining when and where pressure points underneath the sacrum and foot regions were lifted off the bed, but not capable of determining if a scapula pressure point was relieved. These results suggest that the proposed algorithm is effective for some, but not all regions of the body. Future work will therefore focus on detection of all pressure points, and the adjustment of the algorithm for subject independence.