Comparison of Heart Rate Variability of Chronic Spinal Cord Injury Patients in Supine and Sitting Positions

Abstract

Background: Sympathetic and parasympathetic activity shift in response to body position changing. Spinal cord injury (SCI) patients have problems controlling autonomic functions occurs as a result of an imbalance between the sympathetic and parasympathetic nervous systems. Despite the fact that changing body position is often used in SCI rehabilitation, few studies have compared the autonomic activity of SCI patients at different body positions. Heart rate variability (HRV) can be used to invasively assess cardiac autonomic modulation. This study aims to obtain information about the autonomic modulation features of SCI patients in supine and sitting positions using HRV measurements. Methods:This study was a cross-sectional study approach. Participants of this study were 14 chronic SCI patients with injury durations more than a year. Measurement of HRV is using Polar H10 (1B56EB2E). HRV measurements in the subjects of this study were Root Mean Square of the Successive Differences (RMSSD) and Low Frequency/High Frequency (LF/HF) ratio in supine and sitting positions.Results: There was a significant difference in the value of RMSSD in chronic SCI patients from supine to sitting position (p 0.019). There was no significant difference in the value of LF/HF ratio in chronic SCI patients from supine to sitting position (p 0.408).Conclusions: Parasympathetic activity (RMSSD) decreased significantly in chronic SCI patients due to postural changing from supine to sitting position. Despite the fact that sympathetic activity is disrupted in SCI patients, the sympathovagal balance can still be maintained with changes in body position.