From there, a design program was launched following approval of merit review grant application and led to a new and patented shower commode wheelchair.
An iterative design process involving patients and caregivers
Safety: wheelchair must not contribute to the development of pressure ulcers, nor cause injuries to patients due to falls while transferring or bending forward to wash the feet.
Wheelchair positioning over a toilet: must fit properly over a toilet bowl.
Seat design: must be designed to facilitate under seat hand access from 3 sides, be waterproof, provide full thigh support and be cushioned to avoid skin pressure.
Seating position: must be sloped 4 to 5 degrees toward the back to hold the user safely in place.
Armrests: must swing out of the way for transfers, provide a resting-place for the forearms, support the user’s body weight while hooking under them, or lift themselves or re-position their body.
Caregiver friendly: must provide for unrestricted hand access to the perianal area of the patient.
Propulsion pushrim/handrims: must be appropriately sized for optimum hand positioning and grip and be coated with non-slippery material to assist use in wet environments.
Static stability: must be designed for a minimum tip angle of 20° in forward, rearward, and sideways tipping.
Prototype development and testing
The development process involved the design of adjustable wheelchair frames, in order to establish the proper relationship between seat, toilet bowl and bathroom wall. From there folding wheelchair frames were developed. The frames were tested for static stability in accordance with applicable ANSI/RESNA/ISO standards. With the frame geometry established, the other aspects of the wheelchair development followed (see Box 2).
The ability to adjust footrests in order to match the user’s leg height is critical in establishing a good seating position. In developing the new footrests a lever handle was selected to easily lock/unlock/raise and lower them.
An open-weave nylon mesh was selected to facilitate water flow-through in showering.
Typical wheelchairs are equipped with 61cm diameter wheels and 1.9 cm diameter metal pushrims or handrings. Because that wheel height interfered with patient side transfer 55 cm diameter wheels were selected. Hand ergonomic data was used to develop new pushrims to increase grasping in wet environments and propelling. Ten wheelchair users participated in a preference study and selected 3,5 cm as the preferred diameter which was then produced in aluminum and rubber coated.
Clinical evaluation and collaboration with manufacturers
The prototype evaluation involved actual clinical use of the wheelchairs with 20 patients and 20 caregivers at the Milwaukee and Tampa VA Medical Centers. Additionally, a post trial questionnaire was used to rate the wheelchair’s features regarding toileting, showering, seating, transferring, folding-unfolding and self-propelling.
The new wheelchair was found to fit conveniently in shower stalls and over toilets, to improve showering and toileting via the many places available for patients to grasp and hold. The wheelchair held the user in a safe position and provided a wide and comfortable seat. Finally the coated larger size pushrims/handrings faciltated self-propelling especially when wet.
Author : Pascal Malassigné, M.Sc.
Adapted from : Malassigné, P., Nelson, A.L., Jensen, R.P., Cors, M. (2001). “Design, development, evaluation, patenting and licensing of new shower-commode wheelchair. A case study in universal design research.” Proceedings of the 2001 IDSA Education Conference. This research was supported by the Rehabilitation R&D Service of the US Department of Veterans Affairs, Washington DC.
American National Standards Institute (ANSI) /Rehabilitation Engineering Society of North America (RESNA). Wheelchair standards. Washington, DC.: RESNA Press; 1990.