Evaluation of the automatic bottoming-out releasing system in the automatic self-regulating alternating pressure air-cell wheelchair cushion

Abstract

　This study examined whether an automatic bottoming-out releasing system influences interface pressure, bottoming-out, and the integrated value（pressure value × bottoming-out time）. The participants were aged 65 or over, had either a current or previous pressure ulcer on the ischial tuberosity or coccyx area, and experienced problems with their seating position. We used an automatic self-regulating alternating pressure air-cell cushion. The intervention group used cushions with an automatic bottoming-out releasing system. In the control group, this system was turned off. 17 participants were enrolled and 3 outcomes were assessed: interface pressure, rate of total bottoming out, and integrated value. In the intervention group for seating position A, in which the back was in contact with the back support, there was no significant difference between optimized pressure and nonbottoming out（p = 0.16）. In the control group, the interface pressure value associated with non-bottoming out was significantly higher than the optimized pressure（p = 0.00）. The rate of total bottoming out in the intervention group for seating positions A and B（in which the back left the back support and the load was directed perpendicular to the seat）and D（in which individual returned to position A after assuming position B or C, causing movement of the limbs and corresponding shifting of the load）was significantly lower than in the control group（p = 0.00）, as was the integrated value（p = 0.03）. These findings indicate that the automatic bottoming-out releasing system operated appropriately and may be effective in preventing and aiding recovering from pressure ulcers developed in a seating position.