Pressure distribution under the ischium of normal subjects

This paper describes the development of a system for measuring pressure distribution at the patient-support interface. The instrument uses pneumatic techniques under microcomputer control to measure pressures, with an overall accuracy of 3 per cent of full scale. The instrument has been used to investigate the pressure distribution under the ischium of four normal subjects, using a rectangular matrix. The study demonstrated a small variability in pressure distribution with a subject sitting still. Repositioning the subjects produced large variations in pressure readings, as a result of postural changes, which must be taken into account in the design of seating trials.