D-3: Development of Wheelchair Seating Standards
Task Leader: Patricia Karg, MS (bioengineer)
Co-investigators: David Brienza, PhD (bioengineer); Gina Bertocci, PhD, PE (bioengineer); Douglas Hobson, PhD (bioengineer)
Duration/Staging of Task: This 60-month development task will be conducted in all months of the RERC cycle, commencing January 1, 1999.
Rationale/Task Summary
Development of wheelchair seating as a sub-specialty of rehabilitation services has been occurring over the past several decades. This practice involves the selection and provision of wheelchair seating products that seek to provide improved body support and injury prevention to the wheelchair user. Inherent in the seating selection process is the measurement and communication of anthropometric measures, postural information, and pressure distribution needs of the seated user.
Many seating solutions involve an eclectic approach in which the seating products provided by one manufacturer are combined with accessories, such as head or trunk supports, produced by another manufacturer, in order to arrive at a solution appropriate to the needs of the wheelchair user. Although wheelchair manufacturers are providing an increasing variety of seating products that are designed to interface with their wheelchairs, the use of seating devices produced by one or more seating manufacturers in one seating system is still routine practice by both seating practitioners and wheelchair users.
There are several areas of concern that warrant investigation and the development of voluntary industry standards. Four areas have been identified and compose the work proposals for the new ISO and ANSI/RESNA seating standards: terms and definitions, pressure management seating devices, postural support devices, and seating devices for use in motor vehicles.
Terminology is a logical area of initial focus. There is no widely accepted industry terminology for describing wheelchair seating products and their related accessories or their intended function. Standard definitions and terms are lacking for communicating critical postural information in a way that is uniformly useful to clinicians and users when selecting wheelchair seating devices. That is, there is tremendous variation and confusion regarding the terminology and definitions related to wheelchair seating products and related clinical measures.
Among seating products are those intended for pressure distribution and maintenance of soft tissue integrity and those designed to provide postural support. Some products, such as wheelchair cushions, are designed to optimize pressure distribution for persons with a loss of sensation in their buttock tissues and who are at high risk for tissue breakdown. Other products are designed for persons who lack control of their body posture or movement due to central nervous system dysfunction and, therefore, need additional upper torso support and possibly adjustable support surfaces to facilitate function. These latter products are commonly referred to as postural support devices. Despite the large variety of seating products, no general documentation exists to allow consistent comparison of product characteristics and performance, or to guide practitioners and users in the assessment of quality and appropriate selection of these products. The Paralyzed Veterans of America (PVA), Spinal Cord Research Foundation recognizes the need for standardization of seating devices and has, therefore, funded a project that will develop a standardized procedure to define and measure wheelchair cushion characteristics.
And finally, with the advent of ADA, mandatory school busing, and improved adaptations to private vehicles, many more persons with disabilities use their wheelchairs as seats in motor vehicles. Advancements have been made in standards for wheelchair securement, occupant restraint and transport wheelchair devices. However, no standard currently addresses the crashworthy requirements of wheelchair seating products in the event of a vehicle impact when transporting an occupied wheelchair. The need for this standard became very apparent during preparation of the ANSI/RESNA transport wheelchair standard. A group of special-education-based therapists joined forces with a pediatrician to lobby the responsible ANSI/RESNA Subcommittee to include crashworthy add-on seating in the wheelchair standard. The Subcommittee elected to make the work a future priority, pending funding. Since then, the ANSI/RESNA Subcommittee on Wheelchair and Related Seating has been formed and has organized a working group to address this need.
The standards are written for industry and, therefore, industry is the primary target population for this work. The impact of the standards will also affect third party payers of seating products, the providers of seating services and the primary user of wheelchair seating devices. The benefits to these populations are described below.
Beneficial impact on target population and service providers
The standards are written as voluntary documents. The impetus for industry to abide by the voluntary standards is through consumer demand and to reduce liability. The standards act as guidance documents for design and performance by setting specifications and standardizing evaluation practices. Industry will have input into the development of the standards, and will then benefit from their existence by creating products of improved quality and safety.
Third party payers (e.g., HCFA) are struggling to develop reimbursement codes for seating products that are more representative and consistent. They seek objective criteria based upon adequate clinical trials and standardized, independent testing. The development of the seating standards will provide the basis for the objective criteria needed, as well as facilitate better communication between industry, service providers and payers.
The service provider will also benefit from seating standards. With guidance on interpretation and utilization, the seating standards will provide the service provider with standardized terminology to communicate critical postural information. They will provide objective information to allow consistent comparison of seating or measurement device characteristics and performance. In addition, this information could be used to guide practitioners in the assessment of quality and appropriate selection of these devices.
The other population that benefits from the development of voluntary standards for seating devices is the wheelchair user. The benefits to this population are similar to those to the service provider. The standards will provide objective information to allow more informed selection of products by allowing consistent product comparisons and quality assessment.
In order for the standards to impact these populations, dissemination and utilization plans must develop guidance documents and manuals in lay terminology to help interpret the application of the standards and the testing results. Such plans are discussed below in the respective sections.
Development activities
The Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) is an ANSI-accredited standards organization with a Technical Standards Board that overseas and approves the work of the subcommittees. A comprehensive 21-part ANSI/RESNA series of voluntary standards for wheelchairs was developed over an eight-year period (1982-1990) by the ANSI/RESNA Standards Subcommittee on Wheelchairs. This series covers a wide range of design and performance requirements, test methods, and information disclosure requirements. Most wheelchairs now being manufactured and marketed in the U.S. conform to the requirements of the ANSI/RESNA Wheelchair Standards. These Standards to a large extent have been harmonized with Canadian and ISO equivalent standards, so that any barriers to import and export for both consumers and manufacturers should be minimal.
In an effort to rally practitioner, user, and industry support for new work in wheelchair seating standards, the RERC team presented a proposal for a four-part seating standard in two open forums at the International Seating Symposium in Vancouver (March 1998). Based on comments from both national and international participants, the revised working drafts of the four parts were circulated, in both the U.S. and worldwide to ISO participating countries, for approval to begin the seating standards development work. The work proposal contained the following four parts:
- Part 1: Terms and definitions
- Part 2: Pressure management devices
- Part 3: Postural support devices
- Part 4: Seating devices for use in motor vehicles
In June 1998, RESNA's Technical Guidelines Committee authorized the formation of the Subcommittee on Wheelchair and Related Seating Standards and of four interrelated working groups to begin work on voluntary wheelchair seating standards. The attendees at the subcommittee meetings comprise clinicians, consumers, government representatives, manufacturers, and researchers. From the RERC team, Patricia Karg was appointed to chair the Pressure Management Working Group, with Gina Bertocci appointed as chair of the working group for Part 4. The University of Pittsburgh RERC was asked to provide both research and secretarial support for the ANSI/RESNA Subcommittee. In October 1998, four new work items were established under ISO/TC-173/SC-1. Since the initial working drafts for each part are identical for ANSI/RESNA and ISO, this created a unique opportunity for harmonization of the U.S. and International efforts.
Work had already begun that provided support for the development of standards for some seating products. Douglas Hobson co-chaired a RESNA task group that addressed the standardization of terminology by producing a 1992 reference document entitled, "Standardization of Terminology and Descriptive Methods for Specialized Seating". This document is now under revision by the new ANSI/RESNA Subcommittee working group, of which Dr. Hobson is a member. Secondly, a project that developed a standardized procedure to define and measure wheelchair cushion characteristics was awarded by the Paralyzed Veterans of America Spinal Cord Research Foundation to Dr. Stephen Sprigle of Helen Hayes Hospital in 1998. Dr. Sprigle is a member of the Seating Standards Subcommittee and is Vice-chair of the Pressure Management Working Group.
There is a continuous need for technical and organizational support of the seating standards development. The RERC provides this support, as well as provides a means to ensure broad dissemination and utilization of the standards information.
RERC Planned Contribution to the Seating Standards
Goals
- provide leadership and coordinating support for the investigation and development of the standards on both the national and the international levels,
- provide investigative support by conducting cooperative laboratory research and evaluations as determined by the working groups in the development process, and
- foster implementation of the standards.
Progress Report (12/30/00)
Year 1 primarily involved administrative support and leadership/participation in national and international meetings. We constructed and maintained the RESNA seating standards participants database and aided in soliciting balanced participation in the various working groups. We constructed and maintain web pages that provide announcements/meeting information, draft standards, background information, meeting minutes, reference documents, and membership information. The website can be viewed at: http://www.wheelchairstandards.pitt.edu. We created and support listserves for the various working groups. The website and listserves have proven a very effective way to stimulate national and international collaboration, as well as distribute standards documents in a cost-effective and timely manner. Investigative support revolved around literature reviews and defining potential test methods for the draft standards.
Year 2 involved a continuation of the administrative support and leadership/participation in working groups, as well as an increase in investigative/laboratory support. Feedback from participants is that the listserves and web support has been an invaluable and productive tool in the standards development process and should be continued. The participants database was reconstructed and updated to meet the needs of the standards committee and working group chairs. The web pages are continuously updated and are being reworked to reflect organizational changes. Investigative support has surrounded three main areas:
- standard measurement of wheelchair seated posture,
- test methods and data for wheelchair seating use in motor vehicles (see also Task D-5), and
- development and testing of a load-deflection/interface pressure test apparatus for wheelchair cushions.
We end the year with validation of test methods and revision of draft test methods in preparation for the February 2001 ISO deadline for completion of the committee draft for all parts of the seating standard.
In addition to seating standards development work, we have continued to provide input to the SADMERC on alternative coding/evaluation methods for the planned revision of HCFA wheelchair cushion codes, which are directly impacted by the progress made in standards work.
Progress Report (12/30/01)
Year 3 primarily involved a continuation of the RERC providing administrative support (e.g., database, list serves, website), participating in and leading standards meetings, performing validation testing, and support in developing the draft documents for the four parts of the seating standard, ISO 16840, Wheelchair Seatingt. In Fall 2001, commitittee drafts were completed for all four parts of the standard and released for CD voting at the ISO level. The ANSI/RESNA effort will continue to pass draft standards at the national level once the ISO drafts have gone through the voting and response to voting stages.
Following are the committee drafts sent out for voting at the ISO level (Summer/Fall 2001):
ISO 16840-1, Definitions of body and seat dimensions
ISO 16840-2, Test methods for devices intended to manage tissue integrity (text) (graphics)
ISO 16840-3, Postural Support Devices
ISO 16840-4, Seating devices for use in motor vehicles
Please see the wheelchair standards website: http://www.wheelchairstandards.pitt.edu for additional information.
Progress Report (12/30/02)
In Year 4 the RERC continued to provide administrative support in the form of list serves, participants database and the dedicated website. The website was redone to improve ease of use and to update the structure. The investigators continued to participate and provide leadership at meetings and in the development effort. A doctorate student funded by the RERC, Barbara Crane, took on the responsibility to chair the ISO and RESNA group working on the definition of body and seat measures. She has been the primary person responsible over the past year for preparation of the draft documents and organization of the validation efforts for this part of the seating standard. The Task Leader, Patricia Karg, accepted the role of Chair of the RESNA committee responsible for developing the seating standards at the national level. All task investigators have attended meetings and continue to provide expertise and investigative support into the development of the drafts and validation of the draft methods. The investigators also pursued funding opportunities to support the validation testing requirements. Task D3 funds were dedicated in part to fabricating test apparatus and performing the loaded contour and overload test method from the 16840-2 draft on a representative subset of 18 wheelchair cushions. The RERC, along with results from another lab, showed the method was repeatable within and across the two laboratories. Validation efforts for 16840-1 are being funded by the RERC under Task D4 (please see this task for details.) Dissemination and training activities for this past year have included visiting lectures to students, an article in RESNA News, presentation at the International Seating Symposium, and an instructional course and two concurrent sessions at the RESNA 2002 conference. Two graduate students and one undergraduate student have participated in the development and testing activities of the RERC.
At the end of this funding year, the RERC received approval and supplemental funding of approximately 140K in direct funds to be used for further validation testing of the methods in draft 16840-2. This Task will organize and lead this effort that will involve the RERC, as well as five other laboratories. This funding is timely and necessary to allow validation of the draft prior to the final voting stages of the document.
Expected Outcomes
Draft voluntary industry standards in the four work areas listed above
Publications/Reports
Current drafts of all standards, minutes and meeting announcements for each working group can be viewed on the web site: http://www.wheelchairstandards.pitt.edu
Contact Person: Tricia Karg
Acknowledgement:
The primary support for the WMRC is provided by
The Department of Rehabilitation Science and Technology (RST) of the School of Health and Rehabilitation Sciences
