Functional electrical stimulation and reciprocating gait orthosis for ambulation exercise in a tetraplegic patient: a case study.

The purpose of this paper is to report the cardiopulmonary stresses (as indicated by heart rate, blood pressure, oxygen consumption and task cost) for a tetraplegic individual when walking with electrical stimulation and a gait orthosis as opposed to walking with a gait orthosis alone. Functional electrical stimulation (FES), when interfaced with a reciprocating gait orthosis (RGO), resulted in walking exercise for a C-7 level tetraplegic subject, who was 8 years post-injury. Cardiopulmonary measurements were made and task costs calculated on this individual during progressive velocity walking with the FES-RGO and the orthosis alone (without FES). Results for the tetraplegic individual indicate that there were no significant changes in heart rate at the various walking velocities with respect to the two systems. However, systolic blood pressure was significantly reduced at the three highest walking velocities (1.2, 1.6 and 2.0 kph) when using the FES and orthosis system as compared to orthosis-alone walking (p less than .025, p less than .005 and p less than .025 respectively). Calculated oxygen consumption was significantly reduced and calculated task cost improved at the highest walking velocity (2.0 kph) when using the FES-RGO system as compared to using only the RGO (p less than .025). It is concluded that cardiopulmonary stresses are significantly less for this tetraplegic individual when ambulating at the higher velocities with electrical stimulation and a gait orthosis than when walking with a gait orthosis alone. This may result in improved endurance during each walking session and (consequently) an improved aerobic exercise effect. This might also allow some tetraplegics, who would be unable to walk with the RGO alone, to walk with electrical stimulation and the RGO.