The impact of tilting on blood flow and localized tissue loading.

AIM OF THE STUDY The overall goal of this research was to improve the use of seated tilt to increase function, health and quality of life for people using power wheelchairs. Specifically, the objective of this study was to evaluate the biomechanical responses to seated full body tilt in persons with spinal cord injury (SCI). MATERIALS AND METHODS Laser Doppler Flowmetry and interface pressure measurement were employed to measure changes in blood flow and loading at the ischial tuberosities across different amounts of tilt. Eleven participants with SCI were studied in a laboratory setting. RESULTS Results showed that biomechanical responses to tilt were highly variable. Pressure reduction at the ischial tuberosity was not present at 15°, but did occur with tilts to 30° and greater, and could be explained by the tilt position and upright pressure. Unlike pressure, blood flow increased with all tilts from an upright position, but did not increase when tilting from 15° to 30°. Only 4 of 11 participants had increases in blood flow of ≥10% at 30° tilt, whereas 9 participants did during maximum tilt (i.e., 45°-60°). CONCLUSIONS Based on the results of this study, tilting for pressure reliefs as far as the seating system permits is suggested to maximize the potential for significant blood flow increases and pressure relief. The use of interim small tilts is also supported, as they also provide some benefit.