Pressure relief characteristics in alternating pressure air cushions.

In this study a computerised system was used which continuously measured air pressure, interface pressure and pressure-time cycle characteristics of an alternating pressure air cushion (APAC), and calculated the time the interface pressure remained below three chosen thresholds of 20, 40 and 60 mm Hg. Ten healthy volunteers were used to evaluate the pressure relieving characteristics of four APACs. Results indicated significant differences between products when the threshold periods were analysed, showing some devices were not capable of relieving interface pressures below 20 mm Hg. Though deflation pressure decreased to nearer zero, interface pressure did not follow suit.