RESNA Position on the Application of Seat-Elevation Devices for Power Wheelchair Users Literature Update (2019 DRAFT)

RESNA Position on the Application of Seat-Elevation Devices for Power Wheelchair Users Literature Update (2019)

 

Authors:

Vince Schiappa, MS, ATP

Department of Rehabilitation Science and Technology

University of Pittsburgh

Pittsburgh, PA

Julie Piriano, PT, ATP/SMS

Quantum Rehab

Duryea, PA

Lorri Bernhardt, PT, MPT, ATP

Pi Beta Phi Seating and Mobility Clinic

Vanderbilt University Medical Center

Nashville, TN

Mary Shea, MA, OTR, ATP

Wheelchair Services

Kessler Institute for Rehabilitation

West Orange, NJ

Chris Maurer, PT, MPT, ATP

Seating and Mobility Clinic

Shepherd Center

Atlanta, GA

Lauren Rosen, PT, MPT, MSMS, ATP/SMS

Motion Analysis Center

St. Joseph’s Hospital

Tampa, FL

Michelle L. Lange, OTR/L, ABDA, ATP/SMS

Access to Independence, Inc

Arvada, Colorado

Mark Schmeler, PhD, OTR/L, ATP

Department of Rehabilitation Science and Technology

University of Pittsburgh

Pittsburgh, PA

Brad E. Dicianno, MD

Department of Physical Medicine and Rehabilitation

University of Pittsburgh School of Medicine

Pittsburgh, PA

Human Engineering Research Laboratories

VA Pittsburgh Healthcare System, Pittsburgh, PA

Pittsburgh, PA

 

Keywords:

Power features, power seat elevation, power elevating seat, power adjustable seat height, power seat option, seat elevation, wheelchair accessory, transfers, reach, line of sight, rehabilitation.

  1.  Introduction
    1. Purpose

The purpose of this paper is to share typical clinical applications as well as provide evidence from the literature supporting the application of power seat elevation devices.  It is not intended to replace clinical judgment related to specific client needs. Power seat elevation devices address several medical needs. The scientific literature cited here supporting this feature on a wheelchair has been drawn from research conducted with wheelchairs and ergonomic chairs, and in participants with and without disabilities.

A RESNA Position Paper is an official statement by RESNA. Position Papers are not intended to be formal, scientific meta-analyses. Rather, they use evidence and expert opinion to summarize best practices for Assistive Technology (AT) devices, evaluation, and service delivery. Position Papers provide a rationale for decision-making and professional skills for practitioners; and explain the medical and/or functional necessity of AT devices and services for policy makers and funding sources.

  1. Definitions
    1. A power seat elevation device is a seat function component of a wheelchair that raises and lowers users while remaining in a seated position through the use of an electromechanical lift system to provide varying amounts of vertical seat to floor height. It does not change the seated angles or the seat’s angle relative to the ground. A seat elevation device may elevate vertically from a standard seat height or may lower the user closer to the (Arva et al, 2004) floor.
    2. A power elevating seat (PES) is another term used to describe this seat elevation feature.
    3. Power adjustable seat height (PASH) is another term used to describe a seat elevation device.
  2. Background

Wheelchair mobility is often only considered from the perspective of people moving from one point to another on a two-dimensional plane (Arva et al., 2004). Vertical movement is necessary for people to function and participate in a three-dimensional world. A common intervention that provides vertical mobility within a wheelchair is a seat elevation device.  It is RESNA’s position that a power seat elevation device is a medically necessary feature for individuals who require a change in sitting height in the course of performing or participating in one’s activities of daily living (ADLs).

  1. Statement of Position
    1. The Position

Seat elevation is a seat function component that can be operated as a power option on power wheelchairs.  The beneficial effects of this seat function are numerous and have been reported in the previous Statement of Position Paper on this subject (Arva et. al, 2004).  The purpose of this manuscript is to update this RESNA Position on the application of seat elevation devices with more current and additional scientific literature.

It is RESNA’s position that power seat elevation devices are medically necessary, as this technology enables certain individuals to:

  • Facilitate reach biomechanics, safety and range
  • Improve transfer biomechanics, safety and independence
  • Enhance visual orientation and line-of-sight
  • Support psychological and physiological health, safety and well-being.
    • Decrease hyperlordotic position of the neck
    • Promote stable seated positioning
    • Reduce symmetric tonic neck reflex (STNR) activity
    • Improve safety with performance/participation in ADLs.
  • Improve wheelchair pedestrian safety.

A licensed, certified medical professional (i.e. physical or occupational therapist) should be involved with the assessment, prescription, trials and training in the use of the equipment to maximize safe use and functioning from the power seat elevation devices. It is recommended this feature be provided by an AT professional with the knowledge, skills and training in the provision of power wheelchairs and power seating options such as an accredited supplier that employs a RESNA-certified Assistive Technology Professional (ATP) who specializes in wheelchairs and who has direct, in-person involvement in the wheelchair selection.

  1. Populations and Subpopulations Affected

Those who may benefit from recommendations in this position are potential or current users of seat elevation devices as a power function.  Those who are not appropriate for using this seat feature would not benefit from the recommendations.

  1. Precautions, Contraindications or Limits of Use
    1. Cognitive limitations which would prohibit safe use of the feature.
    2. Special precautions must be exercised when utilizing power seat elevation devices to avoid the risk of injury, such as impacting a surface if the wheelchair is under this surface during elevation.
  2. Relevance of Position
    1. RESNA and Constituencies

This paper may have implications on various RESNA related activities and could be used in several ways.

  1. It could serve as a guide to practitioners in the evaluation, recommendation and justification for the provision of power seat elevation devices.
  2. It could be used as a tool in academia to guide education in Assistive Technology related fields of practice.
  3. It could be utilized as a source of support material when there is a need to justify its medical benefits and necessity and provide advocacy for this power seat function.
  4. It could be used as a clinical teaching tool for education of the wheelchair user and other team members.
  5. It could be used to provide evidence in an organized educational format to assist with policy changes and role definition related to power seat elevation devices.  
  6. It could be used as a contribution to the development of a professional standard of practice.
  7. It could be used to promote further research on the medical benefits of this power seat function.
  8. Significance to Society

This paper may have implications to society, including users of assistive technology (AT). It could be used to guide education to consumers about the use of this power seat function to improve their general knowledge and ability to self-advocate for procurement of the feature. It could also be used to impact public policy related to coverage and reimbursement.

  1. Rationale for the Position
    1. Overview of the Current Literature
      1. Facilitate Reach Biomechanics, Safety and Range

Access to the vertical environment is essential for a wheelchair user to perform or participate in their ADLs. As stated in the Wheelchair Skills Training Program (WSP) Manual, “skill in wheelchair use is not an end itself, it is a means to an end” (Kirby et al., 2018). The manual further asserts, “the characteristics of the wheelchair, its features, fit and setup can have major effects on skill performance.” It should be noted that “the skills chosen for inclusion in the Wheelchair Skills Program are intended to be representative of the range of skills that wheelchair users and/or caregivers may need to regularly perform,” such as reaching.

Reaching a high object is included in the WSP because “a combination of upward and sideways or forward reaching is often needed when reaching for a light switch, elevator button or cupboard.” The target for the test is 2.5 cm (1 in.) in diameter and 1.5 m (60 in.) from the floor. To pass the test “the subject reaches up under control, touches the target and then resumes the normal sitting position.” Chair height, and the ability to reposition the seat height, can have an impact on the wheelchair user’s ability to touch the target. Passing the reach test is only the first step in assessing whether an individual can actually reach to perform or participate in their ADLs from the wheelchair (Kirby et al., 2018).

In a survey conducted by Georgia Tech (2017), 100 of 105 (95.2%) respondents indicated that they use their seat elevation device feature “often” or “sometimes” to help reach objects (Table 1). However, the activities in which they are engaged while elevated, such as moving, dressing, grooming, eating/meal preparation, toileting and bathing, differ. The survey did not delineate why people perform activities at different seat heights, but wheelchair users report seat elevation devices on their power wheelchair reduces the effect of environmental barriers to the vertical space.

Table 1

 

Often

 #

Sometimes

 #

Rarely

 #

Never

 #

To help reach things

81.9%

86

13.3%

14

3.8%

4

1%

1

While dressing

16.3%

17

26%

27

17.3%

18

40.4%

42

While grooming (brushing teeth, combing hair, etc.)

39.4%

41

23.1%

24

16.3%

17

21.2%

22

While eating or preparing a meal

59.2%

61

24.3%

25

6.8%

7

9.7%

10

During toileting activities

27.2%

28

17.5%

18

22.3%

23

33%

34

During bathing activities

21%

22

10.5%

11

17.1%

18

51.4%

54

 

Access to the vertical environment is essential for a wheelchair user to perform or participate in their ADLs. Either by building code or convention the standard height of objects an individual must interact with on a daily basis are as follows:

Kitchen countertop height = 36”

Kitchen upper cabinet height = 54” at the bottom, 84” at the top

Freezer height = 50” – 72”

Stove top height = 36”

Over stove microwave height = 50” – 54” at the bottom, 66” at the top

Height for a closet rod = 66”, top shelf = 80”

Washer/Dryer height = 36”, stacked = 75”

Height of a light switch = 48”

Height for a thermostat = 60”

Fire alarm pull height = 42” – 54”

 

When compared to the mean shoulder height in sitting for women (n=2208) at 21.87 in. and men (n=1774) at 23.53” in a standard chair (Gordon et al., 1988), it is clear seated individuals must reach above shoulder height to access any of these areas of the home. Anthropometric measurements also show that the mean vertical grip reach in sitting for the same women is 47.73 in (43.01- 52.32 in.) and 51.57 in. (46.36 – 56.38 in.) for men, which falls short of the heights needed to safely perform or participate in many ADLs, even at the top range of the reach. This may place seated individuals, such as power wheelchair users, at risk for injury and increased healthcare costs from adverse occurrences in their quest for independence.

Requejo et al. (2008) compared the frequency and duration of overhead arm activity between wheelchair users and occupationally matched non-wheelchair users during an 8-hour workday. They found that non-wheelchair users performed an average of 53 (9 – 88) episodes of overhead arm activity while wheelchair users performed an average of 297 (44 – 798) episodes of arm activity during the same time period. The total time spent in an overhead position was five times greater for wheelchair users (mean = 34.6 min., range = 7.9 to 106.6 min.) as compared to standing adults (mean = 6.6 min., range = .4 – 15.5 min.). As a result, they assert that it is imperative for wheelchair users to “minimize extreme or potentially injurious positions at the shoulder by avoiding extreme positions such as hand over the shoulder.” They also state, “based on ergonomics literature, there is a strong association between working above overhead height and shoulder pain in the work environment” and that “use of a wheelchair increases a person’s need for overhead activity to access the environment.” 

Requejo et al. (2008) conclude the increased overhead arm use documented in the study “may contribute to the development of shoulder pathology” and “individuals with [spinal cord injury] (SCI) should avoid extreme shoulder positions, particularly overhead arm activities.” Extrapolated out, any wheelchair user that reaches overhead 297 times/day x 365 days/yr. will reach overhead 542,025 (80,300 – 1,456,350) times during the 5-year reasonable useful lifetime of the power wheelchair. During the same 5 years a person at standing height that reaches overhead 53 times/day x 365 days/yr. will only reach overhead 96,725 (7,300 – 160,600) times. While the study only looked at individuals with SCI this information may be applicable for other individuals with disabilities who use a power wheelchair.

Sabari et al. (2016) state that “the upper limb and neck are common sites for the development of repetitive strain injuries (RSI)” and hypothesized that “the addition of a seat elevating device may alleviate the risk factors that lead to the development of RSI.” They observed 60 ambulatory adults age 18 – 65, seated symmetrically in a power wheelchair who were asked to perform a functional vision task and a functional reach task. Each task was performed at the minimum wheelchair seat height and the maximum seat height.  Results “revealed a statistically significant difference between AROM (active range of motion) required for shoulder abduction to complete the reaching task, when comparing performance with the wheelchair at minimum seat height and at maximum seat height.” They contend “the power seat elevator at its maximum height may allow wheelchair users to perform functional tasks without excessive [end range movement] AROM at the shoulders, thereby decreasing their risk for developing RSI.” While “further investigation would need to test a sample population of long-term wheelchair users,” they conclude that their “findings provide preliminary support for considering [seat elevation] as a medical necessity for wheelchair users who are at risk of developing chronic pain syndromes associated with the shoulder girdle and/or cervical spine.”

According to Schiappa et al. (2017), power seat elevation devices also have a significant impact on the quality of life of end users.  Three groups were analyzed using the Functional Mobility Assessment (FMA) score on reaching during the procurement of a new power mobility device:

  1. with a seat elevation feature, compared to their current device which did not have one;
  2. without a seat elevation feature, compared to their current device that did have one; and,
  3.  with a seat elevation feature, compared to their current device which had one. 

The change in score was significantly different for the first two groups indicating a quality of life change when a seat elevation device was equipped on their power wheelchair.

In its publication, Preservation of Upper Limb Function following Spinal Cord Injury (SCI): Clinical Practice Guidelines for Health-Care Professionals (2005) the Paralyzed Veterans of America (PVA) recommends providing “seat elevationto individuals with SCI who use power wheelchairs and have arm function”. It further states, “even if modification to both the home and work environments are so complete as to totally negate the need for overhead activities, the individual with SCI will still be forced to do them whenever they shop, visit the post office, or check out books at the library”.

It is likely that a person who uses a power wheelchair (PWC) with a low, static seat height will need to reach overhead as many times as a person in a manual wheelchair (MWC) but will have a difficult time executing it. In evaluating individuals with disabilities for the appropriate mobility base, if a manual wheelchair is reasonable and necessary, the expectation is that the individual has sufficient balance, strength, range of motion, coordination, endurance and upper extremity (UE) function to self-propel and perform or participate in their ADLs, including the ability to reach overhead as many times per day as necessary.

In summary, power seat elevation devices can increase vertical reach for increased function in all environments where the power wheelchair is used. In addition, by increasing seat height, less active vertical reach is required for many tasks which can reduce risk of injury and pain in the neck, shoulders and upper extremities.

  1. Improve Transfer Biomechanics, Safety and Independence

“Transferring from a wheelchair to other surfaces such as a bed, toilet, or other surface is a necessary part of the daily routine. Transferring from a wheelchair to another surface such as a bed or toilet is essential to enable individuals to perform their ADLs.  Since transfers are necessary for an individual to perform their ADLs, they should be “considered a medical necessity” (Arva et al., 2009). In a survey conducted by Georgia Tech (2017), 84 of 105 respondents (80%) indicated that they used the power seat elevation device “often” or “sometimes” during transfers to or from the wheelchair.

Wheelchair users must transfer a minimum of twice each day, yet Kim, Her and Ko (2015) found that “among the basic ADL, transfer is a task that is performed by each patient 15 – 20 times per day, on average.”  Regardless of the method used, the ability to adjust the height of the seat, in conjunction with transfer training using an appropriate method and proper technique, is an essential component for independent, safe and efficient transferring to/from the wheelchair.

Sitting pivot transfer (SPT) is the most common transfer method using the upper extremities (Kim et al., 2015). In fact, wheelchair users with absent or significantly impaired use of their lower extremities “must use their upper extremities for almost all activities of daily living (ADLs), such as getting in and out of bed, transferring to a shower or toilet, and transferring in and out of a car” (Tsai et al., 2014).

Sit-pivot transfers are one of the most strenuous wheelchair activities performed, and incorrect transfer skills may predispose wheelchair users to developing upper limb pain and overuse related injuries, such as rotator cuff tears, elbow pain and carpal tunnel syndrome (Tsai et al., 2014). Kim et al. (2015) not only report “pain prevalence rates [of] 58.5%; shoulder: 71%, elbow: 35%, wrist: 53%, hand: 43%”, they also state that SPT is “the most burdensome task for the musculoskeletal system, the nervous system and the cardiovascular system among wheelchair related ADL.”

Kim et al. (2015) “compared the changes in trunk and shoulder angles and reaction forces under each hand at two different seat heights in 18 unimpaired males during independent siting pivot transfer. They found significant increases in the trunk angles of forward and lateral flexion, even though rotation decreased while transferring in the lower hand direction. Increased shoulder flexion, anterior/posterior forces and reduced lateral forces were also shown. Hence, placing the hands of the supporting arms lower than the seat position during sitting pivot transfer was identified as having biomechanical advantages.” They suggest that the results of the study “can be applied as guidelines for effective and safe methods for …spinal cord injury patients’ SPT and can be utilized as reference data when considering the appropriate heights of aids for wheelchairs.”

Clinical evaluation and observation should take into consideration UE, core and lower extremity (LE) strength, range of motion, muscle tone and balance when determining the difference between the seat height of the wheelchair and the height of the surface to be transferred to or from.

Tsai et al. (2014) evaluated whether using proper transfer skills as measured by the Transfer Assessment Instrument (TAI) is associated with reduced loading on the upper extremities in 23 wheelchair users who performed transfers to a level-height bench while a series of force plates, load cells and a motion capture system recorded the biomechanics of their natural transferring techniques. While Part 1, item 5 of the TAI states, “the subject performs a level or downhill transfer, whenever possible” the study removed the height differential and had all participants perform level transfers to validate that the TAI is an effective tool for evaluating transfers on a 15-point scale. The study concluded that, “the transfer skills that can be measured by the TAI are closely associated with the magnitude and timing of joint movements. As such, the TAI may be useful for measuring the effects of a training intervention on upper limb joint loading.” This may include the recommendation of a seat elevating device for power wheelchair users who must perform level or downhill transfers.

Wang et al. (1994) also explored the joint reaction forces and muscle activity changes attributed to transferring from a wheelchair to three different height surfaces.  Six able bodied males between the ages of 20 and 25 performed transfers from wheelchairs to heights below, equal to, and above the chair.  Surface electrodes collected the EMG activation during these transfers.  This study also demonstrated that transferring to higher surfaces resulted in greater muscle force requirements than did transfers to equal surfaces or lower surfaces.  This again stresses the importance of the ability to change seat height to reduce the repetitive stress associated with transfers.

A sit-to-stand (STS) movement, which is defined as a movement of standing up from a chair to an upright posture, is a frequently performed ADL according to Yoshioka, Nagano, Hay, & Fukashiro (2014). They found that “community dwelling people stand up from a [standard] chair approximately 60 times each day.” However, “many people with weakness, pain, or other disabilities of the lower extremities have difficulty rising from a standard seat height” (Burdett, Habasevich, Pisciotta & Simon, 1985).

Janssen, Bussmann & Stam (2002) performed an extensive review of literature from 1980 – 2001 (n=39) on STS movement. They report the “minimum height for successful rising … appears to be 120% of lower leg length” and “lowering the height of the seat makes the STS movement more demanding or even unsuccessful.” Hence, attempting to transfer from a seat height that is too low may be associated with an increase in fall risk.

While a minimum chair height standing (MCHS) ability test has been shown to be effective as a fall risk-screening instrument for older individuals (Reider, 2012), the research did not include individuals with disabilities or those who use power wheelchairs.

Yoshioka et al. (2014) examined “the large range of seat heights on peak joint moments of the lower limbs during STS movement” using 8 healthy, young subjects. They were studied standing up from seat heights of 10 cm (3.93 in.), 20 cm (7.87 in.), 30 cm (11.81 in.), 40 cm (15.7 in.), 50 cm (19.68 in.) and 60 cm (23.62 in.). The study confirmed that, “the peak mechanical load and the peak knee to hip joint movements increase inversely to seat height within the range of high to normal seat height (60 to 40 cm).” The study concludes that “the findings are useful for the design of chair [and] the improvement in the evaluation standard of minimum sit-to-stand height tests.” Therefore, the ability to adjust the wheelchair seat height at a minimum of 20% more than an individual’s specific lower leg length, and even higher for individuals with muscle weakness, can minimize overall LE loads and range of motion required for this repetitive task.

Nakamura, Nagasawa, Sawaki, Yokokawa & Ohira (2016) cite previous studies that report “the vastus lateralis, rectus femoris, and tibialis anterior muscles showed a tendency towards higher activity levels with decreasing seat height” and indicate “standing up from a lower seat height would be more demanding.” To confirm this, they examined “the effect of different seat heights on peak oxygen uptake (peak VO2) during incremental sit-to-stand exercise” with 13 healthy young women. “The seat heights were adjusted to 100%, 80%, 120%, and 140% of knee height distance.” They found that peak VO2 on the incremental sit-to-stand test increased as seat height decreased.” This may have significant implications for individuals who are aging with a disability, and/or exhibit respiratory compromise as a result of their diagnosis or disability.

Schiappa et al. (2017) also found power seat elevation devices have a significant impact on the quality of life of end users related to transfers.  The same three groups were analyzed using the FMA score on transferring during the procurement of a new power mobility device with a seat elevation feature compared to their current device which did not have one, FMA score on transferring during the procurement of a new power mobility device without a seat elevation device compared to their current device having one, and FMA score when being able to maintain a power seat elevation device during the procurement process. Again, the change in score showed a significant difference for the first and second groups indicating a quality of life change when a seat elevation device was equipped on their power wheelchair or not.

Clinically, when evaluating stand-pivot transfers, every sit-to-stand transition can be split into four main phases: flexion (leaning forward), momentum-transfer (seat-off), extension (coming to the upright position) and stabilization (standing) according to Janssen et al. (2002). This is followed by pivoting or stepping and the stand-to-sit transition. While sit-to-stand transfers have been widely studied, there is a significant lack of information concerning stand-to-sit transfers, especially at varying seat heights.

In summary, the ability to change the seat height of the wheelchair in relation to the height of the surface being transferred to can improve transfer biomechanics and efficiency, increase safety, reduce injury and fall risk and promote or maintain independence.

  1. Enhance Visual Orientation and Line of Sight

Numerous studies support the benefits of direct eye contact on both human interaction with others and on the environment. Eye contact can have a positive impact on memory, improve socialization and stimulate cognition (Schreiber et al., 2016; Oda et al., 2011; Conty et al., 2016).  Direct eye contact may provide a means for processing the intentions of communication as well as contributing to non-verbal communication (Jiang et al., 2017).  Level, horizontal gaze improves interactions with the environment which, in turn, improves safety through obstacle avoidance (Diebo et al., 2016).

People seated in wheelchairs are positioned at a lower level than their standing counterparts, which forces an upward gaze to achieve direct eye contact. When interacting with the environment at a seated height, people are forced to maintain an upward gaze in an attempt to visualize many items or events in their home and community. This upward gaze may not be sufficient for certain visual tasks such as seeing into cabinets or on shelves, observing items cooking on a stovetop, utilizing a mirror for grooming and hygiene (shaving, brushing teeth, etc.), and reading information that is secured to a wall (thermostats, menus, maps, calendars, etc.). Use of a seat elevation device provides the required line of sight for these activities. In addition, line of sight improves eye contact with media for learning and is associated with higher performance in school (Volmink et al., 2015).

Many people who sustain an upward gaze tend to hyperextend the neck. The cervical position required to maintain an upward gaze has physical consequences. Diebo et al. (2016) concluded that cervical lordosis (neck hyperextension) is needed to maintain even a horizontal eye gaze in people with increased thoracic kyphosis. Wheelchair users with neurologic and orthopedic impairments frequently have increased kyphosis, which could lead to a tendency toward cervical lordosis. Access to a seat elevation device to achieve horizontal eye gaze for the aforementioned benefits would minimize cervical lordosis and resultant pain.

Sabari et al. (2016) observed 60 ambulatory adults seated in a power wheelchair who were asked to perform a functional visual task and a functional reach task at minimum wheelchair seat height and at the maximum seat height, using a seat elevating device. They found a “statistically significant difference between active range of motion (AROM) requirements for cervical extension to complete the computer viewing tasks, when comparing performance with the wheelchair at minimum seat height and at maximum seat height (t = 15.318, p < 0.001) (Sabari et al., 2016)”. These hyperextended cervical positions may lead to fatigue and pain.

In summary, seat elevation devices can improve visual orientation and line of sight which can provide direct eye contact for memory, socialization, cognition, communication and even safety in navigation. Improved line of sight reduces cervical hyperextension commonly seen in people seated at a typical wheelchair height. This cervical hyperextension can lead to pain and fatigue.

 

  1. Support Psychological and Physiological Health, Safety and Well-being

Wu, Y., Lie, H., Kelleher, A., Pearlman, J., Ding, D. & Cooper, R.A. (2017) assert that “wheelchair discomfort is a very common problem for wheelchair users” and suggest that “increasing the frequency of using PSFs (power seat functions) may decrease wheelchair discomfort.” The chairs used in the study were outfitted with encoders “to record angle changes for tilt, recline, legrests and seat elevation.” The 13 individuals with disabilities that completed the 8-week study in their home and community filled out the Tool for Assessing Wheelchair discomfort (TAWC) each day. The results showed that “wheelchair discomfort intensity is correlated with the frequency of using tilt, recline and legrest functions” and the frequency of using these functions “were not correlated with each other.” While the study does not discuss what impact power seat elevation devices may have on discomfort, it does state “wheelchair discomfort might result from other medical or physiological factors and the maximal improvement of wheelchair comfort that PSFs can achieve should be further investigated.”

Clinical observation of wheelchair users sitting at a low seat height highlights the fact that they are forced to extend the cervical spine to levels that contribute to pain when interacting with other people or objects in their environment.

Kirby, R.L., Fahie, C.L., Smith, C., Chester, E.L., & Macleod, D.A. (2004) studied 20 wheelchair users who assumed and maintained four neck positions for 5 minutes each to determine if they experienced more discomfort in an extended or rotated position as compared to their self-selected most comfortable position (MCP). “The MCP for wheelchair users is straight ahead with the neck slightly flexed.” However, to make eye contact with the average height seated male, the wheelchair user had to extend their cervical spine 11°. Cervical extension increased to 27° when looking up at an average height standing male. They conclude “sustained extension and rotation of the neck, alone or in combination, increase the neck discomfort of wheelchair users” and contend “these findings have implications for wheelchair design”.

Sabari et al. (2016) suggest “frequent hyperextended cervical positions are likely to lead to fatigue of the soft tissue structures of the cervical region, and significant discomfort can be expected when these positions are sustained.” Results of their study “reveal a statistically significant difference between AROM requirements for cervical extension to complete the computer viewing tasks, when comparing performance with the wheelchair at minimum seat height and at maximum seat height.” They state that their study findings “provide support for the potential benefit of a seat elevation device in reducing the arcs of motion required to extend the neck, and thereby minimizing the risk for RSI at the neck.” Their data supports “previous recommendations that wheelchair users of all physical statures may benefit from the various advantages of a power seat elevation device, especially in minimizing the risk for the development of pain in the neck and secondary complications” such as cervical myelopathy.

One additional, adverse implication of neck hyperextension that may be observed in individuals who look up from a low seat height is the elicitation of the symmetric tonic neck reflex (STNR). The STNR is triggered by flexion or extension of the neck. When the neck flexes, the arms flex and the legs extend; conversely when the neck extends, the arms go into extension and the hips and legs flex. This may result in a loss of seated position, and discomfort in individuals with cerebral palsy who have retained the STNR, or in individuals that have suffered a stroke or traumatic brain injury where the STNR has re-emerged. Unfortunately, there is no research that has looked at the effect a symmetric tonic neck reflex has on seated position, discomfort in the seated position as a result of an STNR, or whether the application of a power seat elevating devices minimizes the effect of an STNR on posture by maintaining a neutral neck position. However, observing and detailing the impact of seat elevation for the one person (n=1) being evaluated for a power wheelchair is what is ultimately required to establish the medical need for the feature.

In summary, when a person is positioned with the neck hyperextended, this can lead to fatigue, pain and even the elicitation of the STNR. Power seat elevation devices can reduce neck hyperextension by improving line of sight through increasing seat height.

  1. Improve Wheelchair Pedestrian Safety

Following the results of their study, Kraemer, J., & Benton, C. (2015) call for a priority of policy changes related to disability accommodations for pedestrians who use wheelchairs.  Their study was designed to describe and quantify the fatal pedestrian crashes among persons using wheelchairs in the USA from 2006 to 2012.  Two sources were used to provide a capture-recapture analysis.  A descriptive analysis of the fatal crashes was also conducted.  The capture-recapture analysis utilized data of fatal crashes that were recorded by the National Highway Traffic Safety Administration (NHTSA) Fatality Analysis Reporting System, and the LesixNexis US newspaper database.  For the capture-recapture estimation the fatal crashes in the two registries were matched. 

A comparison of pedestrian death risk in the general US population (determined by the Centers for Disease Control and Prevention (CDC) fatal injury report database) was calculated in relation to the rate of fatalities in the wheelchair pedestrian population.  The results indicate that pedestrians using wheelchairs have about a one-third higher risk of mortality when compared to the overall pedestrian population. 

Further descriptive analyses of the circumstances surrounding the accidents identified that the “low conspicuity of wheelchair users appears to play a large role in the risk of mortality.  This finding is consistent with the finding that 75% of the crashes involved no driver avoidance maneuvers.  The results indicate that pedestrians using wheelchairs have about a one-third higher risk of mortality when compared to the overall pedestrian population.  Further descriptive analyses of the circumstances surrounding the accidents identified that the “low conspicuity of wheelchair users appears to play a large role in the risk of mortality.  This finding is consistent with the finding that 75% of the crashes involved no driver avoidance maneuvers. 

The authors summarize the disparity in safety for pedestrians using wheelchairs compared to the normal population.  Further, due to the significant disparity, these authors call for a priority in policy changes to improve the safety of pedestrian wheelchair users.  They cite the Americans with Disability Act which requires public settings to be accessible to persons with disabilities.

  1. Evidence of Use

In a recent study designed to look at how people actually use a seat elevating device in their everyday life instrumentation was placed on 24 power wheelchairs with seat elevators to measure wheelchair occupancy, seat height, in-seat activity level and bouts of mobility (Sonenblum et al., 2019), 453 days of seat elevation and mobility data was collected. Time in chair, # of transfers (in and out), # of times seat elevated, center of pressure movement, amount of time spent in the elevated positions and # of times seat elevated >9” were among the variables studied.  “The average day included a mean (SD) of 8.4 (4.9) hours in the wheelchair. During the average day participants transferred 8.5 (6.0) times in and out of their wheelchair. On average, participants elevated their wheelchair 3.9 (4.4) times per day, with an average of 1.0 (1.6) elevation per day extending past 9”. Ten participants used their wheelchair in an elevated position every single day of the study, while the remaining 14 had at least one day in which they did not use the elevating feature. However, the study documented 1,943 events in which participants elevated their seat above 1”. 16 of 24 (67%) participants transferred while elevated at least one time during the study. Most transfers took place at heights less than 5” or greater than 9”, and 14 people changed their seat height between the transfer out of the wheelchair and the return transfer at least one time. They reported reach and gaze (line of sight) as being the most often purpose for elevation. Across all days and seat heights, participants had a frequency of active segments 17.7 (25) times per hour they were seated in their wheelchair. Comparing the in-seat activity level while elevated to those when the chair was below 1”; however, shows an increased in-seat activity level while elevated (diff = 42.6 (341.8) per hour” insinuating that the participants experienced increased reach access when elevated. In addition, “23 of 24 participants wheeled while elevated”, although few reported using the seat elevator for the purpose of mobility. Overall there was a high variability within and across subjects which is consistent with other measures of wheelchair use. Participants varied from using the feature on a daily basis to more intermittent, but it still provided a functional benefit to their daily lives.

  1. Case Examples

Josh

Josh was diagnosed with Limb-Girdle Muscular Dystrophy at the age of 8. At age 25, he presents with poor strength in all 4 extremities and poor to fair core strength. He has poor sitting balance and does not have the ability to perform a sit-pivot or sliding board transfer. His standing balance is also poor and he is non-ambulatory; however, by standing with his hips and knees hyperextended he is able to “lock” the joints and use the structural integrity of his ligaments to do a stand-pivot transfer independently while holding on to the armrests of the chair.

      With the wheelchair seat elevated to 31”, Josh is still able to perform a stand-pivot transfer independently to and from his bed, which is also elevated to 31” regardless of whether he is in his own apartment or in his old room at his parent’s house. At any lower seat height, he is fully dependent on a personal care attendant to transfer. In addition, Josh also remains fully independent in managing his bladder needs as he is able to stand from his wheelchair at a seat height of 31” to use the toilet.

Madonna

Madonna sustained an incomplete spinal cord injury at the T10 level at age 18. She used a manual wheelchair for 35 years but at 53, as she ages with a disability, she began experiencing significant pain and strength limitations in her neck, shoulders and upper back from overuse injuries. As a single parent, she found herself reaching overhead hundreds of times each day to cook, clean and do laundry from a low, static seat height, exacerbating her pain. In addition, she sustained third-degree burns twice while removing a hot, cooked item from the stove due to the poor biomechanical position of her upper extremities from a low seat height. Madonna has now used a power wheelchair with a seat elevation feature for 2 years, reports a significant reduction in UE pain and no adverse occurrences. She attributes this to adjusting her wheelchair seat to the appropriate height for the task she is performing, thereby saving thousands of dollars in medical care.

Lisa

Lisa is a 30-year-old graphic designer with arthrogryposis and contractures of her arms and legs. Her elbows are contracted in extension and she does not have shoulder strength to raise her arms to shoulder height. She therefore performs many tasks with her mouth. She uses a seat elevation device to raise her seat height so that she can perform tasks with a mouth stick, such as operating her microwave, using a keyboard on a podium during presentations, adjusting her thermostat, and accessing elevator buttons. She also uses the seat elevation device when transferring into bed. With the seat height adjusted to the same level of her bed she is still able to perform 50% of the transfer.

Mary

Mary is a 60-year-old woman with inclusion body myositis. Her strength has declined such that she relies on a mechanical lift for safe, dependent transfers. Her husband is her primary caregiver.  He has back issues. To significantly reduce risk of injury to her during the transfer process he elevates the chair to its full height to place her in an uncompromised position and get into and out of the wheelchair safely. This feature eliminates the need for patient care assistance (PCA) for transfer needs. For Mary it also saves the healthcare system thousands of dollars as 1 hour of PCA, at $10/hour x 365 days per year would otherwise cost a minimum of $3650 annually.

Mark

Mark was born with cerebral palsy. He is fully independent in all his activities of daily living at the wheelchair level even though he presents with spasticity in all four extremities. When Mark looks up from a low seated position, he elicits a significant STNR that triggers spasticity and involuntary movement that results in him flexing his legs (right greater than left) and extending his arms (left greater than right). This causes him to lose his positioning in the wheelchair and appropriate contact with his cushion and back, which can result in injuries, especially on the seated surface, due to shearing forces. In addition to the discomfort it causes him, this reflexive response also negatively impacts his ability to reach and function to perform his ADLs throughout the day.

Kiel

Kiel sustained an incomplete spinal cord injury at the C5/6 level. In addition to an increased risk for shoulder and neck RSI, Kiel has a critical use for his power seat elevation system as he reaches and adjusts the thermostat in his home. Kiel experiences thermoregulatory dysfunction secondary to his spinal cord injury. Thermoregulation is the process that allows the human body to maintain its core temperature. Thermoregulatory dysfunction in individuals with SCI refers to the fact that their body cannot perform this function properly. As a result, Kiel needs to be able to adjust the thermostat independently for his health and safety.

While he can reach the thermostat at a height of 48” from a low, static seat height, he is unable to see what temperature he has adjusted it to without the capability of adjusting the height of his wheelchair seat. Vertical adjustment provides him the visual access he needs to support this reaching activity, independently manage this condition and not incur additional PCA hours or medical costs from an adverse occurrence.

 

  1. Issues Related to Practice, Policy, and Research

A dearth of literature exists on long term outcomes related to provision of seat functions and comparisons of different clinical models of their provision. While the preponderance of evidence supports the medical benefits of a power seat elevation device as a component of a power wheelchair more research on the impact of policy and funding on user outcomes remains.

  1. Conclusion

Power seat elevation devices allow an individual who uses a power wheelchair to independently change their seat to floor height. Increasing seat height can increase functional reach as well as decrease the amount of overhead reaching that is required. Overhead reach can lead to injury and pain of the shoulder, neck and upper extremities. Changing the seat height in relation to other surfaces can increase transfer safety and efficiency as well as reduce injuries and fall risk. Seat elevation devices can also improve line of sight with others and with the environment. Without a more direct line of sight, individuals in wheelchair tend to assume cervical extension which can lead to fatigue, pain and even elicitation of an STNR. Power seat elevation devices are an important power wheelchair seat function which can improve overall function; safety; efficiency; and reduce fatigue; injury; and pain to minimize the risk for adverse medical outcomes and resulting healthcare costs.

  1. Limitations of the Current Literature

Limitations of the current literature include small sample sizes, absence of high-level experimental randomized clinical trials, and lack of longitudinal data on medical outcomes.

  1. Relation of this Position Paper to Previous Position Papers

This Position Paper is an update of the previously published Position Paper (Arva et al., 2009). Triggers of new findings that would require an update of the position include a new published formal, scientific meta-analysis, would provide stronger evidence than this Position and would require an update of the current Position. However, at this time insufficient literature exists to conduct a formal, scientific meta-analysis

d) References

Arva, J., Schmeler, M.R., Lange, M.L., Lipka, D.D., & Rosen, L.E. (2009). RESNA Position on the Application of Seat-Elevating Devices for Wheelchair Users. Assistive Technology, 21(2), 69-72.

Burdett, R.G., Habasevich, R., Pisciotta, J., & Simon, S. (1985). Biomechanical Comparison of Rising from Two Types of Chairs, Physical Therapy, 65(8), 1177-1183.

Conty L, George N, & Heitanan J. (2016). Watching Eyes effects: When others meet the self. Consciousness and Cognition. 45, 184-197.

Diebo, B., Challier, V., Henry, J., Oren, J., Spiegel, M., Vira, S., Lafage, V. (2016). Predicting Cervical Alignment Required to Maintain Horizontal Gaze Based on Global Spinal Alignment. Spine, 41(23), 1795-1800.

Gordon, C.C., Churchill, T., Clauser, C.E., Bradtmiller, B., McConville, J.T., Tebbetts, I & Walker, R.A., (1988). Anthropometric Survey of U.S. Personnel: Summary Statistics Interim Report, Retrieved from https://multisite.eos.ncsu.edu/www-ergocenter-ncsu-edu/wp-content/upload...

Janssen, W., Bussmann, H., & Stam, H. (2002). Determinants of the Sit-to-Stand Movement: A Review, Physical Therapy, 82(9) 866-879.

Jiang, J., Borowiak, K., Tudge, L., Otto, C., & Kriegstein, K. (2016) Neural Mechanisms of Eye Contact When Listening to Another Person Talking. Social Cognitive and Affective Neuroscience, 12(2), 319–328.

Kim, S., Her, J., & Ko, T. (2015). Effect of different hand positions on trunk and shoulder kinematics and reaction forces in sitting pivot transfer, Journal of Physical Therapy Science, 27(7), 2307-2311.

Kirby, R., Fahie, C., Smith, C., Chester, E., & Macleod, D., (2004). Neck discomfort of wheelchair users: effect of neck position, Disability & Rehabilitation, 26 (1), 9-15.

Kirby, R., Rushton, P., Smith, C., Routhier, F., Best, K., Cowan, R., Worobey, L. (2018) The Wheelchair Skills Program Manual. Published electronically at Dalhousie University, Halifax, Nova Scotia, Canada. www.wheelchairskillsprogram.ca/eng/manual.php

Kraemer, J., & Benton, C. (2015).  Disparities in Road Crash Mortality Among Pedestrians Using Wheelchairs in the USA:  Results of a Capture-Recapture Analysis, BMJ Open, 5:e008396, 1-8. doi:10.1136/bmjopen-2015-008396

Nakamura, K., Nagasawa, Y., Sawaki, S., Yokokawa, Y., & Ohira, M. (2016). Effect of Different Seat Heights during an Incremental Sit-To-Stand Exercise Test on Peak Oxygen Uptake in Young, Healthy Women. Journal of sports science & medicine15(3), 410-416.

Oda, R., Niwa, Y., Honma, A., & Hiraishi, K. (2011). An eye-like painting enhances the expectation of a good reputation. Evolution and Human Behavior, 32(3), 166-71.

Paralyzed Veterans of America Consortium for Spinal Cord Medicine (2005). Preservation of upper limb function following spinal cord injury: a clinical practice guideline for health-care professionals. The journal of spinal cord medicine28(5), 434-70.

Rehabilitation Engineering & Applied Research Lab; Georgia Institute of Technology. (2017). Survey of Users of Wheelchair Seat Elevators. Retrieved from http://hdl.handle.net/1853/59106

Reider, N. (2012). Minimal Chair Height Standing Test Performance is Independently Associated with Falls in a Population of Canadian Older Adults, Master’s Thesis, University of Victoria (Unpublished), retrieved from https://dspace.library.uvic.ca/bitstream/handle/1828/4374/Reider_Nadia_MSc_2012.pdf?sequence=1&isAllowed=y

Requejo, P.S., Mulroy, S.J., Haubert, L.L, Newsom, C.J., Gronley, J.K., & Perry, J. (2008). Evidence-Based Strategies to Preserve Shoulder Function in Manual Wheelchair Users with Spinal Cord Injury. Topics in Spinal Cord Injury Rehabilitation, 13(4), 86-119.

Sabari, J., Shea, M., Chen, L., Laurenceau, A., & Leung, E. (2016). Impact of Wheelchair Seat Height on Neck and Shoulder Range of Motion During Functional Task Performance. Assistive Technology, 28(3), 183-189.

Schiappa, V., Schmeler, M, Schein, R, Dicianno, B., Henderson, G., Hickey, C., & Saptono, A. Functional Satisfaction with Power Wheelchair Seat Elevators. (2017). Presented at the International Seating Symposium, Nashville, TN, USA.

Schreiber, K., & Hausenblas, H. (2016). What Eye Contact Can Do For You. Psychology Today. Retrieved from https://www.psychologytoday.com/us/blog/the-truth-about-exercise-addicti...

Sonenblum, S.E., Maurer, C.L., Hanes, C.D., Piriano, J., & Sprigle, S.H. (2019). Everyday Use of Power Adjustable Seat Height (PASH) Systems. Manuscript submitted for publication

Tsai, C., Hogaboom, N.S., Boninger, M.L., & Koontz, A.M. (2014). The Relationship between Independent Transfer Skills and Upper Limb Kinematics in wheelchair Users, BioMedical Research International.

Volmink L.P. (2015). The Role of Eye Contact in Promoting Effective Learning In Natural Science in the Secondary School. Master Thesis, Department of Education, University of South Africa, November 2015.

Want, Y.T., Kim, C.K., Ford, H.T., & Ford, Jr., H.T. (1994). Reaction Force and EMG Analyses of Wheelchair Transfers. Perceptual and Motor Skills, 79(2), 763-766.

Wu, Y., Liu, H., Kelleher, A., Pearlman, J., Ding, D., & Cooper, R.A. (2017). Power seat function usage and wheelchair discomfort for power wheelchair users. The Journal of Spinal Cord Medicine, 40(1), 62-69.

Yoshika, S., Nagano, A., Hay, D.C., & Fukashiro, S., (2014). Peak hip and knee joint movements during a sit-to-stand movement are invariant to the change of seat height within the range of low to normal seat height. BioMedical Engineering Online, 13(27).

 

Appendices

Summary of the Position Paper Development

RESNA, the Rehabilitation Engineering and Assistive Technology Society of North America, is the premier professional organization dedicated to promoting the health and well-being of people with disabilities through increasing access to technology solutions. RESNA advances the field by offering certification, continuing education, and professional development; developing AT standards; promoting research and public policy; and sponsoring forums for the exchange of information and ideas to meet the needs of our multidisciplinary constituency. Find out more at www.resna.org.

Detail of the Development and Review Process

This Position Paper was developed through RESNA’s Special Interest Group in Seating and Wheeled Mobility (SIG-09). The authors of this manuscript are clinicians and researchers experienced in the field of AT, and specifically, the seat function discussed in this manuscript. A working group was established from RESNA members interested in this topic who volunteered to serve on the Position Paper revision committee. Each member conducted a literature review of articles which were published since the previous Position Paper and indexed in Pubmed. The search included papers that evaluated individuals with disabilities and also control participants wherein the content was relevant to the effects of seating and positioning on body structures and function. The team compiled references into a complete bibliography which was then reviewed and summarized. Additional articles were found through reviewing the bibliographies of individual manuscripts. This search identified articles which were not part of the original Position Paper. A draft manuscript was posted on the RESNA website, and the authors read and incorporated the comments that were posted. The process for position paper development, review, and approval is discussed further in the Procedures for the Development and Approval of RESNA Position Papers on Clinical Practice available at www.resna.org.

Comments

Submitted by Elaine T. Lu PT... (not verified) on

Great paper and research. This is a very needed addition to the current accessible systems. It facilitates patient functional independence, safety, and quality of life in so many ways. Love the research....well done!!

Submitted by Eileen Garza (not verified) on

I love the paper and you have covered all of the situations that I have encountered to support seat elevation. I suspect that you avoid references to work and focus on the ADLs due to funding emphasis, but if it does not impede the purpose of your paper I suggest some reference to the work place/educational settings as contexts for individuals in power chairs because seat elevation is utilized heavily in those areas-for the reaching, social, and other reasons that you mention. In the precautions it might be useful to address seat elevation when driving. You have a section that addresses pedestrian accidents, but, in my experience, some chairs disengage the drive when seats are elevated because of the change in center of gravity. That may be a problem that has been remediated in more contemporary models though.

Submitted by Cathy Carver (not verified) on

Well done to all the authors and contributing articles to this update! It is much needed and will be used in all the intended ways in academia and clinically and in policy. I wanted to contribute insight from a consumer (4th grader with a rare version of M. Dystrophy) that showed me another angle of use of Power Seat Elevate and it was accessing her environment - a version of reach. Due to her significant UE weakness she used the Power Seat Elevate to get her body above the task she wanted to complete and then would let gravity take her hand down to the surface she was accessing - like raising up and using gravity to get her hand on the lever of the door to open it. THen she could stay home and have a safe way to get in/out of her home. To get her Power Seat Elevate covered I asked her to make her list of how she used her current Seat Elevator and this 9 year old young lady send this list back: (BCBS covered it by the way)

To reach buttons on school elevator

To order lunch in school cafeteria and to reach buttons to pay for lunch.

To access multiple desks and tables in school, at home and elsewhere; to reach books and supplies in classroom and library and at home

To wash hands at her wheelchair accessible sink at home and elsewhere--hygiene

To brush teeth independently--hygiene

For egress from our home -- she uses the elevator to get leverage to push down the door lever

Entry and exit to her bedroom and bathroom

To reach light switches throughout house, especially in bedroom and bathroom

For social access to peers

To use our kitchen island for meal prep

Accessing kitchen drawers for utensils, straws, napkins, etc

For returning dishes to sink after meals.--general kitchen/house access and homelife contribution

To relieve pressure and to assist with transfers

To reach doorbell when door is locked

Caring for her pet guinea pig

Library/Grocery store/bank/restaurants/other retail outlets--she could do all these things independently with elevator and anterior tilt.

To write on the board at school

To fill a cup of water--nutrition

Thanks again for all the hard work!

Submitted by Angela Regier (not verified) on

Suggested content on anterior tilt for the RESNA Position on the Application of Seat-Elevation Devices for Power Wheelchair Users Literature Update (2019)

Recommend inclusion of content under the following sections within the position paper:
Addition of section under 2. Rationale for the Position > a. Overview of the Current Literature > vii. Influence of Power Seat Elevation on Related Power Seat Functions

Due to the “combination of upward and sideways or forward reaching” often required of functional tasks, when used in combination with power seat elevation, power anterior tilt can aid in optimization of functional reach. In a pilot study of 10 individuals Rice, Yarnot, Mills and Sonsoff (in press) found that use of anterior tilt improved mean distance of functional reach in the vertical plane significantly between study visit 1, (use of power seat elevation only, functional reach 25.04 +/- 10.53 cm) and study visit 3 (use of power seat elevation and power anterior tilt, functional reach 30.38 +/- 7.29 cm). Further, of the four individuals who identified they would pursue anterior tilt in the future, reach was improved significantly in the horizontal plane with a mean increase of 7.87 cm from study visit 1 to study visit 3, after an initial adjustment period to use of anterior tilt. Since power seat elevation is required for achievement of anterior tilt at higher degrees, these two power seat functions used in combination are integral in maximizing functional reach in multiple planes, ultimately providing the opportunity for individuals to participate in tasks from a forward-facing position (Cherng et al., 2009). This is important for a variety of functional tasks such as safe meal preparation where one must lean over and reach the cooking surface, and retrieval of items such as when grocery shopping (Rice et al., in press). Increases in reach, both in the vertical and horizontal plane through the addition of anterior tilt may further reduce the risk of injury and pain to the upper extremities known to be caused by overhead reaching.

In the study by Rice et al., positive trends, while not significant, in the data were identified regarding transfer quality when using anterior tilt. The way in which participants were instructed to utilize the power seat functions at each study visit varied slightly. In study visit 2 (power seat elevation and initial exposure/use of power anterior tilt), participants were encouraged and instructed on how to best incorporate anterior tilt to assist with their transfers. While in study visit 3 (power seat elevation and post 14 days of power anterior tilt use), no instruction was given regarding which power seat function(s) to utilize during completion of the Transfer Assessment Instrument. This variation in instruction serves as a reminder to the importance of adequate end user training and education, particularly when new power seat functions are available on chair, in order to maximize the functional benefits of power seat function usage. It is important to note that participants who did not typically utilize an anterior chest support on their own chair found the use of this support on the study chair challenging at times, as with the knee blocks. Results from the pilot study by Rice et al. showed trends supporting the positive benefits of anterior tilt as compared to seat elevation alone on a variety of functional tasks.

Cherng, R. J., Lin, H. C., Ju, Y. H., & Ho, C. S. (2009). Effect of seat surface inclination on postural stability and forward reaching efficiency in children with spastic cerebral palsy. Research in Developmental Disabilities, 30(6), 1420-1427.

Rice, L. A., Yarnot, R., Mills, S. & Sonsoff, J. (in press). A pilot investigation of anterior tilt use among power wheelchair users. Disability and Rehabilitation: Assistive Technology.

Respectfully,
Angela Regier and Karin Leire (RESNA Members)
Cc Permobil Academy Clinical Education Team

Submitted by Angela Regier (not verified) on

This feedback is provided in response to the open comments period for the updated RESNA Position on the Application of Seat-Elevation Devices for Power Wheelchair Users. The following general comments are offered, along with specific examples/comments per section listed thereafter.

General Comments:

A. The Glossary of Wheelchair Terms and Definitions, Version 1.0 (Waugh & Crane, 2013) is the current industry standard to reference for accepted terminology and definitions. Therefore, it is recommended that the term power seat elevation be the term used throughout the position paper, and the appropriate reference included. If additional terminology is going to be utilized, such as power elevating seat (PES) and power adjustable seat height (PASH), it is recommended that these terms be referenced as to their source.
Waugh, K., & Crane, B. (2013). Glossary of wheelchair terms and definitions, Version
1.0. Assistive Technology Partners.

B. Integration of the World Health Organization’s International Classification of Functioning, Disability and Health – By integrating the ICF model, and perhaps summarizing the available literature within this framework, it would help to reduce the division of home and community and emphasize activity and participation being inclusive of all environments of use. Summarizing according to this model would also help clarify research needs and support a call to action for power seat elevation research efforts moving forward.

C. Inclusion of anterior tilt – Please see separately submitted suggested language for inclusion of power anterior tilt. Due to the integral nature of anterior tilt in maximizing a variety of functional tasks included in this position paper (e.g., functional reach, transfers, etc.), it is recommended that anterior tilt be included. Just as power tilt, recline, and elevating legrests are presented together in one position paper, the full functional picture and benefits of power seat elevation and anterior tilt should be discussed in combination – not in isolation. Because we do rely on position papers to inform practice, inform end-users, and strive for better reimbursement and understanding of technology the paper should be thorough in its scope regarding how different functions interact for optimal client outcomes. If it is determined by this committee that anterior tilt should be addressed separately, it is recommended that it be done so as an addition/addendum vs. a separate position paper since anterior tilt is utilized in conjunction with seat elevation to optimize client outcomes. For many client’s, these two seat functions when used in isolation of each other result in reduced functional benefits vs. when being used in combination.

D. Call to action/future research needs – In addition to the stated Limitations of the Current Literature, inclusion of a Call to Action/Future Research Needs should be included. While it is important to state the limitations of the studies included in the paper regarding sample size and level of evidence, this paper is also an opportunity to help set the course for future research on this topic. For example, an emphasis on functional environmental access; home safety considerations (thermostat access, medication, food/hydration), the health economics of power seat elevation (how does purchase of a $2,000 power seat elevator save money in the long term due to reduced incidence of repetitive strain injury, caregiver burden, etc), the implications for return to work/school (being a contributing member of society), and the psychological benefits of power seat elevation.

Additional Comments by Section:

1. Introduction:
a. ii. Purpose, Background
Use of “function” vs. “feature” - Using the terms function or component reinforces that power seat elevation is a “need to have” vs. a “nice to have”.

b. iii. Statement of Position, Precautions, Contraindications or Limits of Use
Recommend the addition of language regarding safe driving practices and surfaces when in elevation to avoid risk of injury. Consider adding this as another example after the language, "Special precautions must be exercised when utilizing power seat elevation devices to avoid the risk of injury such as...operation on level surfaces only as stated in the owner’s manuals of all major manufacturers.

c. Relevance of Position
Recommend including examples of what is meant by “practitioners”, e.g., occupational therapy practitioners, physical therapy practitioners, etc.

2. Rationale for the Position:
a. i. Overview of the Current Literature, Facilitate Reach Biomechanics, Safety and Range
As quoted from the Wheelchair Skills Training Program (WSP), “a combination of upward and sideways or forward reaching is often needed when reaching for a light switch, elevator button or cupboard.” (Kirby 2018). This supports the need for inclusion of anterior tilt within this position paper, as power seat elevation alone does not address forward reach.

When quoting the Preservation of Upper Limb Function Following Spinal Cord Injury: Clinical Practice Guidelines for Health-Care Professionals, recommends providing “seat elevation or possibly a standing position to individuals with SCI who use power wheelchairs and have arm function”, “or standing” is omitted in this position paper. While this is a position paper on power seat elevation, the inclusion of standing within the CPG is relevant, as it supports the need to also move closer to something in a horizontal plane, not just vertical (for which power seat elevation addresses). By omitting “or standing” from this quote, the full functional picture is not conveyed.

a. v. Overview of the Current Literature, Improve Wheelchair Pedestrian Safety
Suggest elaborating on the “low conspicuity of wheelchair users appears to play a large role in the risk of mortality” discussion. Consider explaining that “low conspicuity” means the automobile driver may not see the average wheelchair end-user due to lower seat to floor heights. The wheelchair end-user may be more easily seen by automobile drivers (less conspicuous) if the seat was elevated within view of the auto driver. A detailed list of average windshield heights for sedans, SUVs, and trucks compared with the average height of a person sitting in a wheelchair would further exemplify this point.

a. vii Case Examples
Include a case example that describes the benefit of power seat elevation for community use. Relate usage to MRADLs in the community for example retrieving objects from high shelves in a grocery store, accessing a copy machine, speaking from a podium, meeting the eye gaze of standing-level colleagues at work, crossing streets in seat elevate where they can be seen by automobile drivers, etc.

b. Conclusion
The paper states, “Increasing seat to floor height can increase functional reach…” Suggest clarifying that increasing seat to floor height increases vertical reach, and when used in combination with other power seat functions such as anterior tilt and standing to increase horizontal reach as well, functional reach is improved. If we use the Modified Functional Reach Test as a standard for defining functional reach, then we should be including consideration of the horizontal plane throughout the discussion.

Katz-Leurer, M., I. Fisher, et al. (2009). "Reliability and validity of the modified functional reach test at the sub-acute stage post-stroke." Disabil Rehabil 31(3): 243-248. www.rehabmeasures.org

c. Limitations of the Current Literature
Consider adding that much of the data included is from able-bodied individuals. As stated previously, inclusion of a “Future Research Needs” or “Call to Action” would help define additional research needs and set the course for research efforts moving forward.

Respectfully,
Angela Regier and Karin Leire (RESNA Members)
Cc Permobil Academy Clinical Education Team

Submitted by Barbara Crume (not verified) on

Excellent work everyone! It was a pleasure to read all of the studies and information provided. I would like to suggest adding the need for power seat elevate combined with anterior tilt and/or power stand. I know this is not a feature that all power chairs offer but is often required for power chair users. The latter two functions do not operate without the power seat elevate.
Here is one example:
Tylor is a 23 year old with diagnosis of Spastic Quadriplegia Cerebral Palsy who has used a power wheelchair since he was 3-4 years old. He had spinal fusion surgery at age 15 and his hip flexion is limited to R 55 degrees and L 60 degrees due to hip subluxations. He has tight hamstrings despite previous surgical release. He is unable to sit upright and requires a significantly open seat to back angle of 30+ degrees to accommodate his ROM limitations, otherwise he will slide out of the seat. He is unable to flex his trunk to functionally reach forward for any activities including but not limited to reaching the sink to wash his hands or brush his teeth. The use of power seat elevate combined with power anterior tilt to 30 degrees and anterior knee support allows him to function and perform his own grooming tasks and other ADLs in addition to providing visual access to his environment.

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