EVALUATING THE EFFECT OF PATTERN OF INFLATION AND DEFLATION AND CYCLE TIME ON THE PRESSURE RELIEVING CHARACTERISTIC OF A DYNAMIC SEAT CUSHION USING SEAT INTERFACE PRESSURE MEASUREMENTS

Abstract

Ulceration due to pressure can occur in any individual who is restricted to a prolonged stay in a bed or a chair with no pressure relief. Intermittent pressure relief has been recommended as a means to lower the risk of pressure ulcer development. Active cushions cyclically change the area of exposure to pressure. The design parameters of these cushions have been rarely discussed and studied. The main objective of our study was to examine the effect of pattern of inflation/deflation and cycle time on pressure relieving characteristics of active cushions and to compare the performance of these active cushions with a passive cushion. Two custom active cushions were developed based on Roho Quadtro passive cushion design with inflation/deflation patterns: checkerboard (CHK) and column (COL). These were compared to a passive Roho Quadtro cushion (PAS). Two cycle times, 6min. and 12min., of inflation/deflations were tested. Ten non-disabled individuals were tested. Interface pressure was measured for 24min. using the Xsensor pressure mapping system. Peak and mean pressures, percent surface area in contact under 30 mmHg for a cumulative time of at least 5 minutes (S>5), mean percentage of activated sensors under three thresholds (20, 30 and 40 mmHg; P5), mean percentage of activated sensors under three thresholds (20, 30 and 40 mmHg; P5, P5 and P<20 compared to PAS. Cycle time of 12min. developed higher peak pressures compared to 6min. cycle. It was clear that active cushions have an advantage over passive. The design of these custom cushions: air channel distribution and pattern of connection, may have influenced the results. Further testing with disabled individuals and re-designed cushions is needed to fully understand the importance of pattern, cycle time and air cell size.