Pressure Shifting

Q35. Describe the impact on pressures of shifting pressure to the back support, forward leaning, tilting to one side and dynamic loading (moving around in chair)?
1. Shifting pressure from the ischial area to the back support as well as the middle and anterior aspects of the cushion appears to decrease average ischial interface pressure (see figure 11).
2. Average maximum point pressure at the ischial tuberosities (ITs) is most significantly reduced by 45 degrees of forward leaning.
3. 65 degrees of tilt (see figure 12) has significant reduction in maximum point pressure at the ITs whereas 35 degrees of tilt did not demonstrate significant reduction in pressure at the ITs.
4. Lateral trunk leaning to 15 degrees reduces pressure on the unweighted side, but note the study did not evaluate the impact on the weighted side.
5. Backrest recline decreased mean maximum pressures in the IT area but also causes the greatest IT shift (up to 6 cm).
6. Peak interface pressure is greater for dynamic movement in SCI subjects than static sitting but cumulative loading is comparable between dynamic and static loading for this population.
For more information please see: Shifting Pressure


Figure 11. Shifting Pressure post SCI                           

Figure 12. Tilt System

Source: Copyright © 2010 University of Washington/MSKTC