Associations between arterial stiffness and blood pressure fluctuations after spinal cord injury.

ABSTRACT

STUDY DESIGN: Cross-sectional. OBJECTIVE: To examine the relationship between arterial stiffness and daily fluctuations in blood pressure (BP) owing to hypotensive events and autonomic dysreflexia (AD) in individuals with a T6 and above spinal cord injury (SCI). SETTING: University-based laboratory in Vancouver, BC, Canada. METHODS: Twenty-six individuals (73% male; 43 (11) years) with a chronic (> 1 year post SCI), traumatic, motor-complete SCI with a neurological level of injury of C4-T6 participated in this study. Arterial stiffness was assessed using carotid-to-femoral pulse wave velocity (cfPWV). BP was measured over a 24-hr period using ambulatory BP monitoring. AD was defined as an increase in systolic BP > 20 mmHg above baseline BP. Hypotensive events were defined as a decrease in systolic BP ≥ 20 mmHg and/or diastolic BP ≥ 10 mmHg below baseline. The severity and frequency of these events were quantified and Pearson and Spearman's correlations between them and cfPWV were performed. RESULTS: AD severity and frequency were not were correlated with cfPWV. For hypotensive events, both the frequency (r = 0.412, P = 0.04) and severity (Δsystolic BP; r = -0.425, P = 0.03) of these events were correlated with cfPWV. The combined total of AD and hypotensive events (9 (5) events/day) was also correlated with cfPWV (r = 0.480, P = 0.01). CONCLUSIONS: Hypotensive events, and the combined frequency of both hypo- and hypertensive events within a 24-hr period are associated with increased arterial stiffness in individuals with T6 and above SCI, suggesting BP instability may play a role in arterial stiffening post SCI.