Comfort, postural support and/or maintenance, pressure management and function in a wheelchair are all influenced by the person’s ability to physically move themselves by weight shifting and/or repositioning. If the person is unable to independently perform these movements, the use of power positioning devices such as tilt, recline and stand may be added to a power base to facilitate weight shifting or repositioning. The effectiveness of the addition of a power positioning device to a power wheelchair is related to if and how the device is used throughout the person’s day. The studies below have examined how power tilt is used during the day, tracking parameters such as frequency and amplitude of position change.
In their 2009 study, Sonenblum et al. monitored the daily use of power tilt with 16 participants over a one-two week period of time with a secondary purpose of determining if regular pressure relieving tilts (PRT) were being used. Daily use was defined as the length of time the person was in the wheelchair (wheelchair occupancy) as well as the range, frequency and duration of tilt positions used. PRT were defined as tilts greater than 30° for more than one minute, performed once per hour. The findings indicated great variability in wheelchair and tilt use between participants. Wheelchair occupancy ranged from five to 16.6 hours per day with six participants spending over 12 hours per day in their wheelchair. The wheelchair occupancy average was 11 hours per day. The typical position used also varied greatly. Ten participants spent the majority of time in less than 15° tilt, five of whom spent 90% of time in this range; the other five spent the majority of occupancy time in a medium tilt (15-29°) range. Only one participant achieved the suggested PRT. This study found that most participants varied greatly in how much tilt they used. However, tilt positions changed frequently throughout the day even if it was only between two different positions within a small range. Participants identified the most common purposes for using tilt as being for comfort/discomfort/pain and rest/relaxation.
Sonenblum and Sprigle (2011b) findings were similar to the above study. Wheelchair occupancy and large amount of variability in the amplitude, duration and frequency of tilt use were consistent between studies. On average wheelchairs were configured with approximately 100º of recline angle. Tilt-in-space was used for relieving discomfort (77%), pressure relief (73%), rest and relaxation (66%), posture (48%), and function (61%). The frequency of tilting varied from once per day to every three-four minutes. Both studies found that people spent the majority of time in small to medium tilt position with infrequent PRTs (median 0.1 with a range of 0.0 to 2.2 per hour). The size of the tilt change (magnitude) was reported to be predominantly small (0-14°) suggesting that people make small changes in position but are not using the full range of position changes available in the devices.
There is level 5 evidence (one observational study, one descriptive study; Sonenblum et al. 2009, Sonenblum & Sprigle, 2011b) suggesting that on a daily basis, power positioning devices are used for a variety of reasons but predominantly in the small ranges of amplitude, and with great variability of frequency and duration.
Patterns of use for power positioning devices are variable but typically in small ranges of amplitude, with the primary reasons for use being discomfort and rest.