Effect of functional neuromuscular stimulation on postural related orthostatic stress in individuals with acute spinal cord injury.
The purpose of the study was to evaluate the cardiovascular responses of functional neuromuscular stimulation (FNS) on postural-related orthostatic stress in individuals with acute spinal cord injury. Two tetraplegics and three paraplegics participated in this study. A repeated measure design was used in which subjects underwent two graded-tilt table (0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees) orthostatic stress tests with and without FNS (randomized treatment order) of the knee extensors and foot plantar flexors. Successive one-minute digital readings of heart rate (HR) and blood pressure were obtained with an electronic pulse oximeter and automated blood pressure monitor, respectively. Analysis of covariance (ANCOVA) revealed significant test position (tilt angle) and treatment condition (with or without FNS) main effects, but no significant interactions. Between-treatment pairwise contrasts showed that systolic blood pressure was lower without FNS for 15 degrees, 30 degrees, 45 degrees g, and 60 degrees of tilt, while diastolic blood pressure was lower without FNS at 30 degrees and 45 degrees of tilt. In contrast, HR showed a progressive rise with increasing tilt angle. Functional neuromuscular stimulation may be an important treatment adjunct to minimize cardiovascular changes during postural orthostatic stress in individuals with acute spinal cord injury.