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Evaluation of a pushrim-activated, power-assisted wheelchair
R A Cooper1, S G Fitzgerald, M L Boninger
1Human Engineering Research Laboratories, VA Rehabilitation Research & Development Center, VA, USA. rcooper+@pitt.edu
Objective:
To evaluate a novel pushrim-activated, power-assisted wheelchair (PAPAW) for compliance with wheelchair standards, metabolic energy cost during propulsion, and ergonomics during selected activities of daily living (ADLs).
Design:
A 3-phase study, the second and third of which were repeated-measures designs.
Setting:
A rehabilitation engineering center within a Veterans Affairs medical 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 accordance with the wheelchair standards of the American National Standards Institute and the Rehabilitation Engineering and Assistive Technology Society of North 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 strength, impact strength, fatigue strength, environmental response, obstacle climbing ability, range, maximum speed, and braking distance. Phase 2: Subjects' oxygen consumption per minute, minute ventilation, and heart rate during different speeds and workloads with a PAPAW and their own wheelchairs. Phase 3: Subject ratings of perceived comfort and basic ergonomics while performing selected ADLs. Completion time, stroke frequency, and heart rate during each ADL.
Results:
Phase 1: The PAPAW was found to be in compliance with wheelchair standards. Phase 2: With the PAPAW, the user had a significantly lower oxygen consumption (&Vdot;O(2)mL/min: p <.0001; &Vdot;O(2)mL/kg x min: p <.0001) and heart rate (p <.0001) when compared with a manual wheelchair at different speeds. Phase 3: The PAPAW had a significantly higher mean 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 the 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 wheelchair 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 physiologically stressful means of mobility with few adaptations to the vehicle or home environment.