Power Positioning Device Use
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.
Total Sample Size
|Sonenblum & Sprigle 2011a
|Population: Mean age: 44.0 yr; Gender: males=33, females=12; Injury etiology: SCI=30, multiple sclerosis=4, cerebral palsy=4; Level of injury: cervical=29, thoracic=1; Level of severity: incomplete=15, complete=14, ineligible=1.Intervention: Wheelchair occupancy and seat position of participants were monitored for 1–2 wk using an accelerometer, occupancy switch and data logger.
Outcome Measures: Type of wheelchair or cushion, Wheelchair tilt and recline angles, Uses of tilt-in-space, Wheelchair typical position, Tilt usage.
|1. Complete wheelchair configuration was available for 38 participants, of which 29 could tilt their wheelchairs past 45º. On average wheelchairs were configured with approximately 100º of recline angle.2. Tilt-in-space was used for relieving discomfort (77%), pressure relief (73%), rest and relaxation (66%), posture (48%), and function (61%).
3. Small and medium tilts were used more frequently than large and extreme tilts (p=0.000).
4. Year in a wheelchair was negatively associated with tilt frequency (p=0.047) and diagnosis of SCI was associated with greater tilt frequencies (p=0.043).
5. Participants with the ability to reposition spent significantly more time in a small tilt than those with no ability to reposition (p=0.030).
|Sonenblum & Sprigle 2011b
|Population: Mean age: 45 yr; Gender: males=15, females=30; Wheelchair: power=100%; Injury etiology: SCI=30 multiple sclerosis=4, cerebral palsy=4, other=7.Intervention: Monitored wheelchair occupancy and tilt position (typical position; time spent in small (0°-14°), medium (15°-29°), large (30°-44°), and extreme (>45°) magnitude tilts; tilt frequency; pressure-relieving tilt (i.e., moving into >30° for minimum of 1 min) (PRT) frequency) for 1-2 wk.
Outcome Measures: Data logger, accelerometer and occupancy switch.
|1. 77% of patients reported using their tilt-in-space systems for comfort, discomfort, or pain, 73% for pressure relief, 67% for rest/relaxation, 48% for posture, and 61% for function.2. Occupancy time median of 12.1 (range 4.1 – 24) hr/day.
3. Each participants’ typical position utilized a tilt position (median=8°; range 0°-47°).
4. The median participant tilted every 27min, with PRTs performed less frequently (median participant performing one every 10h).
5. 81% of time for the median participant was spent in small tilt, 15% in medium, 1% in large and 0% in extreme tilt.
6. The size of tilt change (magnitude) for the median participant=70% small changes, 19% medium, 4% large and 0% extreme.
|Sonenblum et al. 2009
|Population: Median age: 46 yr; Gender: males=11, females=5; Injury etiology: SCI=10, Other=6; Median time since injury: 6 yr.Intervention: Wheelchair use for 2 wk.
Outcome Measures: Self-report related to reason for using tilt, Electronic logging of tilt utilization, Daily wheelchair occupancy time, Typical position, Time spent at different tilt angles tilt frequency, Pressure relieving tilt (PRT) frequency.
|1. Occupancy: mean of 11 hr/day, range 5.0-16.6; 6 subjects spent over 12 hr/day in wheelchair.2. Typical position: 10 subjects spent a majority of time in less than 15° tilt, 5 of whom spent 90% of time in this range; 5 spent majority of time in medium tilt range.
3. Time spent in different degrees of tilt: eight reached an extreme tilt range.
4. Median frequency of 3.1 tilts/hr.
5. Tilt seldom used for performing PRT (median 1 PRT/7 hr).
6. No significant difference in use based on self-reported purposes (p>0.10).
7. Subjects reporting use of tilt for PRT did not perform more PRT (p=0.60) or use extreme tilts more than counterparts (p=0.67).
8. Only one subject performed ≥2 tilt/hr.
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. 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. This study also found that most participants varied greatly in how much tilt they used, and 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.
In a separate study, Sonenblum and Sprigle (2011a and 2011b) found similar results to the above study in regard to wheelchair occupancy and great variability in the amplitude, duration and frequency of tilt use. All studies found that people spent the majority of time in small to medium tilt position with infrequent pressure relieving tilts (i.e. greater than 30° of tilt). The size of the tilt change (magnitude) was reported to be predominantly small (0-14°) but with a range of frequencies in tilt use, suggesting that some people make small changes in position using tilt but are not using the full range of position changes available in the devices.
There is level 5 evidence (three observational studies: Sonenblum et al. 2009; Sonenblum & Sprigle 2011a; and 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.