Index

Research Tasks

Design and Development Tasks

Support Tasks

RERC-I Final Report-(1993-98)

R-2: Investigation of Dynamic Seating for Comfort

Task Leader: Douglas Hobson, PhD (Rehabilitation Engineer)

Co-Investigators: Mark Friedman, PhD (researcher, industry rep.); Stephen Stadelmeier, MSc (industrial designer); Paul Dick (wheelchair user, consumer advocate)

Others: Barb Crane, MA, PT, graduate student

Duration/Staging of Task: This 39 month research task will be conducted in months 22-60 of the 60 month RERC cycle.

Rationale/Task Summary
Historically, due to the high costs associated with decubitus ulcers, the research effort in wheelchair seating has focused on seating technology for static pressure management (Cooper et al., 1997). Another population that has received the significant R&D focus has been children with neuromotor impairments that render them unable to use standard wheelchair seats (Hobson, 1990). Very little investigation has been directed towards the population of wheelchair users who have normal or near normal sensation and are debilitated by their inability to achieve adequate relief from sitting discomfort, and in some cases, pain.

For able-bodied persons, relieving pain or discomfort during normal sitting is accomplished through small, unconscious body movements or postural adjustments that maintain discomfort at tolerable levels. Persons with advanced stages of Multiple Sclerosis (MS), Muscular Dystrophy (MD), Amyotrophic Lateral Sclerosis (ALS), in addition to those with Post Polio Syndrome (PPS), are considered representative of the target population that experience this problem. Due to their neuromuscular disorder, they are often unable to adjust their body position to attain adequate relief from pain and discomfort. Relief is not possible because the person's motor system (muscles) is unable to carry out the voluntary movements necessary to reduce the pain or discomfort to tolerable levels. In addition to the potential for decubitus ulcer formation, people in this population experience intolerable periods of discomfort, which can lead to reduced participation in daily activities including, work, education, and recreation.

In summary, this task will focus on dynamic seating for discomfort relief for a population of wheelchair users who are unable to independently attain normal relief from chronic sitting discomfort or pain. We will involve representatives from the target populations throughout the process and will investigate both user needs and the use of prototype technology not traditionally used by the wheelchair seating industry.

Specific Objectives
The overall objectives of this task are to prioritize user needs and preferences, and then identify and demonstrate the potentially new dynamic seating technologies to meet the needs. These objectives will be realized through systematically pursing investigations of the following hypotheses:

• Hypothesis #1: Persons within the target population can subjectively rate (quantify) their level of sitting discomfort.
• Hypothesis #2: Persons within the target population can self-monitor discomfort and arrive at acceptable levels of relief when provided the capacity to self-adjust their seated posture and/or their support surface characteristics.
• Hypothesis #3: Persons within the target population will elect to alter their support surface characteristics (shape/resiliency) vs. postural change (back recline, tilt-in-space) in order to retain function and attain acceptable levels of discomfort relief.

Progress Report (1/29/01)

This task began on 1/01/01. The team has had four start up meetings to refine and confirm the research protocol. This has been submitted to the Universities IRB office and given official approval on 1/25/01. Two parallel directions are being taken for Phase I of the study. The first is to locate commercial trucking and heavy equipment seating technology that has adjustment features that may be beneficial to the target population. Several options have been located and one ordered. The second activity is to development, test and finalize a questionnaire instrument that will allow collection of self-assessment data of a person's seat comfort in their own wheelchair. This will be followed by a similar assessment in the trial commercial seat. Ten subjects will be recruited for this beta trial. The anticipated outcome will be a refined instrument that will be used in the larger study. The second outcome of Phase I will be a needs/desires profile that will drive the design criteria for the Phase II test seats. These multi-adjustable seats will then be mounted on powered bases and given more extensive user evaluations (02).

Progress Report (12/30/01)

The task is divided into three phases, phase I is the needs assessment phase, phase II is development and testing of the seating comfort evaluation survey, and phase IIIe is the dynamic seating intervention evaluation phase. Phase I – the needs assessment phase, has been completed. Due to modifications to Phase I, the IRB was revised and re-approved on May 15, 2001. Phase I consisted of two parts – a questionnaire based survey of a sample of individuals in the target population and a test of the MK-I dynamic seating system under development. Nine participants completed the survey and six of those participants completed the in-chair testing. The results of phase I were consistent with information found in the literature review and are being used in development of the Mk-II prototype seat that will be used for phase III testing. Based on feedback from the advisory board concerning possible confounding of phase III results, phase III testing procedures have been modified in order to identify the effects of the newness of the device versus the effectiveness of the dynamic features themselves. A conference paper based on the results from phase one has been submitted and will be presented at the International Seating Symposium in March of 2002. Phase II – seating assessment survey development and testing -- will begin in February of 2002 and Phase III in September of 2002.

Informal report of Phase I results

Progress report (11/21/02)

In December of 2001 Barbara Crane, graduate student involved in this task, successfully submitted a doctoral proposal based on this research task. The proposal called for an expansion of the research phases originally planned. A Phase 1b was added to the research in order to obtain more information from wheelchair users that would further guide development of a discomfort assessment tool. Following approval of this doctoral research proposal, the IRB for this project was modified to include the expanded research proposal and was approved on April 11, 2002. Data collection was begun immediately following this approval and was finalized in August of 2002. The first draft of the wheelchair seat discomfort assessment tool (WCS-DAT) was then developed and sent out to the phase 1b subjects for a member-checking process to validate the content. Following this validation, the WCS-DAT was distributed to Barb Crane’s dissertation committee and this project group for further refinement. Final testing documents were developed to be used in phase 2 data collection and were approved by the IRB on September 18, 2002. Phase 2 data collection was begun shortly after this and is expected to be completed by the end of this year. Test-retest reliability, to date, has indicated that the WCS-DAT is highly stable, and reliability testing continues.

Development of the second-generation dynamic seat test wheelchair has continued over the past year. This seat – known as the Mk-II prototype has many of the features incorporated in the Mk-I system, but was designed to be more functional for testing in real-life environments. The seat to floor height of this wheelchair is similar to products currently available in the wheelchair seating market and the instrumentation is designed to be more robust, more compact so that it does not extend beyond the foot print of the wheelchair base, and has more capability for data storage in order to be capable of storing data for a minimum of 8 day intervals. Phase 3 testing is targeted to begin in January of 2003.

A conference paper based on phases 1 and 1a was presented in March, 2002 at the International Seating Symposium in Vancouver, Canada. A conference paper based on phase 1b has been accepted for presentation at the ISS conference in Orlando, Florida in February of the coming year. In addition to this, a workshop based on this project has been accepted for presentation at the annual RESNA conference in June of the coming year.

Phase 1b summary report

Contact: Douglas Hobson