Impact of sitting time on seat-interface pressure and on pressure mapping with multiple sclerosis patients.

OBJECTIVE To examine changes in seat-interface pressure with multiple sclerosis (MS) patients. DESIGN Case series. SETTING Multiple Sclerosis Society's Resource Centre and community. PARTICIPANTS Convenience sample of 15 MS wheelchair users and 12 MS non-wheelchair users. INTERVENTION Interface pressure was measured for 8 minutes using the Force Sensing Array pressure mapping system. MAIN OUTCOME MEASURES Number of activated sensors, standard deviation, average and maximum pressures. RESULTS With the wheelchair users, significant decreases were found in the standard deviation and average and maximum pressures during 0 to 2 minutes of sitting ( P <.01). Average pressure was the only parameter to show a significant decrease in the non-wheelchair users ( P <.01) during 0 to 2 minutes. Significant increases were found in all output parameters during 2 to 4 minutes with both groups ( P <.05). Non-wheelchair users showed no significant changes in the output parameters after 4 minutes, but wheelchair users showed significant continued increases in the output parameters from 4 to 8 minutes ( P <.05). CONCLUSIONS Because no significant changes in interface pressure occurred after 4 minutes of sitting with the non-wheelchair users, 4 minutes may be a reasonable sitting time before interface pressure is recorded with this group. Significant changes in interface pressure continued up to 8 minutes with the wheelchair users, therefore 8 minutes or beyond may be a reasonable sitting time before recording with this group.