Lessons learned from the pilot study of an orthostatic hypotension intervention in the subacute phase following spinal cord injury.

Context: Following spinal cord injury (SCI) at the cervical or upper-thoracic level, orthostatic hypotension (OH) is observed in 13-100% of patients. This study aimed to test the feasibility of conducting a randomized controlled trial combining a dynamic tilt-table (Erigo®) and functional electrical stimulation (FES) to mitigate OH symptoms in the subacute phase after SCI. Design: Pilot study. Setting: A tertiary rehabilitation hospital. Participants: Inpatients who had a C4-T6 SCI (AIS A-D) less than 12 weeks before recruitment, and reported symptoms of OH in their medical chart. Interventions: Screening sit-up test to determine eligibility, then 1 assessment session and 3 intervention sessions with Erigo® and FES for eligible participants. Outcome measures: Recruitment rate, duration of assessment and interventions, resources used, blood pressure, and Calgary Presyncope Form (OH symptoms). Results: Amongst the 232 admissions, 148 inpatient charts were reviewed, 11 inpatients met all inclusion criteria, 7 participated in a screening sit-up test, and 2 exhibited OH. Neither of the two participants recruited in the pilot study was able to fully complete the assessment and intervention sessions due to scheduling issues (i.e. limited available time). Conclusion: This pilot study evidenced the non-feasibility of the clinical trial as originally designed, due to the low recruitment rate and the lack of available time for research in participant's weekday schedule. OH in the subacute phase after SCI was less prevalent and less incapacitating than expected. Conventional management and spontaneous resolution of symptoms appeared sufficient to mitigate OH in most patients with subacute SCI.

Cardiovascular response of individuals with spinal cord injury to dynamic functional electrical stimulation under orthostatic stress.

In this pilot study, we examined how effectively functional electrical stimulation (FES) and passive stepping mitigated orthostatic hypotension in participants with chronic spinal cord injury (SCI). While being tilted head-up to 70 (°) from the supine position, the participants underwent four 10-min conditions in a random sequence: 1) no intervention, 2) passive stepping, 3) isometric FES of leg muscles, and 4) FES of leg muscles combined with passive stepping. We found that FES and passive stepping independently mitigated a decrease in stroke volume and helped to maintain the mean blood pressure. The effects of FES on stroke volume and mean blood pressure were greater than those of passive stepping. When combined, FES and passive stepping did not interfere with each other, but they also did not synergistically increase stroke volume or mean blood pressure. Thus, the present study suggests that FES delivered to lower limbs can be used in individuals with SCI to help them withstand orthostatic stress. Additional studies are needed to confirm whether this use of FES is applicable to a larger population of individuals with SCI.

Cardiovascular response to functional electrical stimulation and dynamic tilt table therapy to improve orthostatic tolerance.

Orthostatic hypotension is a common condition for individuals with stroke or spinal cord injury. The inability to regulate the central nervous system will result in pooling of blood in the lower extremities leading to orthostatic intolerance. This study compared the use of functional electrical stimulation (FES) and passive leg movements to improve orthostatic tolerance during head-up tilt. Four trial conditions were assessed during head-up tilt: (1) rest, (2) isometric FES of the hamstring, gastrocnemius and quadriceps muscle group, (3) passive mobilization using the Erigo dynamic tilt table; and (4) dynamic FES (combined 2 and 3). Ten healthy male subjects experienced 70 degrees head-up tilt for 15 min under each trial condition. Heart rate, blood pressure and abdominal echograms of the inferior vena cava were recorded for each trial. Passive mobilization and dynamic FES resulted in an increase in intravascular blood volume, while isometric FES only resulted in elevating heart rate. No significant differences in blood pressure were observed under each condition. We conclude that FES combined with passive stepping movements may be an effective modality to increase circulating blood volume and thereby tolerance to postural hypotension in healthy subjects.