Evaluation of a pushrim-activated, power-assisted wheelchair

Objective: To evaluate a novel pushrim-activated, power-assisted wheelchair (PAPAW) for compliance with wheelchair standards, metabolic energy cost du ring propulsion, and ergonomics during selected activities of daily living (ADLs). Design: A 3-phase study, the second and third of which were repeated-measur es designs. Setting: A rehabilitation engineering center within a Veterans Affairs medi cal center. Patients: Eleven full-time, community-dwelling, manual wheelchair users (4 women, 6 men) with spinal cord injuries or multiple sclerosis. Interventions: Phase 1: Compliance testing, with a test dummy, in accordanc e with the wheelchair standards of the American National Standards Institut e and the Rehabilitation Engineering and Assistive Technology Society of No rth America. Phase 2: Metabolic energy consumption testing-at 2 speeds and 3 resistance levels-in subjects' manual wheelchair and the PAPAW. Phase 3. Evaluation of ability to perform ADLs and ergonomics of the PAPAW compared with the subjects personal wheelchair. Main Outcome Measures: Phase 1. The PAPAW's static stability, static streng th, impact strength, fatigue strength, environmental response, obstacle cli mbing ability, range, maximum speed, and braking distance. Phase 2. Subject s' oxygen consumption per minute, minute ventilation, and heart rate during different speeds and workloads with a PAPAW and their own wheelchairs. Pha se 3: Subject ratings of perceived comfort and basic ergonomics while perfo rming selected ADLs. Completion time, stroke frequency, and heart rate duri ng each ADL. Results: Phase 1: The PAPAW was found to be in compliance with wheelchair s tandards. Phase 2: With the PAPAW, the user had a significantly lower oxyge n consumption ((V) over dotO(2)mL/min: p < .0001; (V) over dotO(2)mL/kg x m in: p < .0001) and heart rate (p < .0001) when compared with a manual wheel chair at different speeds. Phase 3: The PAPAW had a significantly higher me an ergonomic evaluation (p < .01) than the subjects' personal wheelchairs. The results of comparing the ratings of the car transfer between the PAPAW and the subjects' personal wheelchair showed a significant difference in th e task of taking the wheels off (p < .001) and putting the wheels back on ( p = .001), with the PAPAW receiving lower ratings. Conclusion: This study indicated that the PAPAW is compliant with wheelchai r standards, reduces the energy demand placed on the user during propulsion , and that subjects rated its ergonomics favorably when compared with their personal wheelchair. PAPAWs may provide manual wheelchairs with a less phy siologically stressful means of mobility with few adaptations to the vehicl e or home environment.