EVIDENCE OF AUTONOMIC DYSREFLEXIA DURING FUNCTIONAL ELECTRICAL-STIMULATION IN INDIVIDUALS WITH SPINAL-CORD INJURIES

The purpose of the investigation was to examine the safety and efficac y of functional electrical stimulation (FES)-assisted hydraulic resist ance training in improving cardiovascular fitness in persons with spin al cord injuries. The cardiopulmonary responses of 10 high spinal cord injured (SCI) and five able bodied (AB) subjects were assessed during three bouts of FES-assisted leg extension exercise. The protocol invo lved three 30-minute tests: (1) unloaded leg extension, (2) hydraulica lly-resisted leg extension (loaded), and (3) a reproduction of the unl oaded and loaded protocols to measure cardiac output (Q). Pre-measurem ents were made of body mass, mean limb weight, maximal force output an d maximal oxygen uptake (incremental arm ergometry). Oxygen uptake (VO 2), minute ventilation (Ve), respiratory exchange ratio (RER), heart r ate (HR), blood pressure (BP) were recorded before, during and after t ests. There was a significant difference in VO2 max between SCI and AB subjects. Cardiac output significantly increased between the loaded a nd unloaded tests. The significant increases from rest to unloaded and loaded exercise pointed to the potential value of adding resistance t o a leg extension training regime. Heart rate and BP of the participan ts with SCI consistently demonstrated a response suggestive of autonom ic dysreflexia. Upon stimulation an immediate increase in (predominant ly systolic) BP was observed, followed by a fall in HR. On cessation o f stimulation HR exhibited a substantial rebound effect and BP returne d to normal levels. This response was highly reproducible and suggests caution be exercised in the use of FES for people with SCI with lesio n levels above the major splanchnic outflow (T6).