Heart rate and blood pressure response improve the prediction of orthostatic cardiovascular dysregulation in persons with chronic spinal cord injury

Figures

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  Figure 1. Prevalence of orthostatic hypotension determined by consensus statement (AAS/AAN, 1996; Freeman et al., 2011) by Cervical, High Thoracic, and Low Cord levels and severity of injury (determined by ISNCSCI (Kirshblum et al., 2011). Orthostatic hypotension is defined as a drop in systolic blood pressure (≥20 mmHg) and/or diastolic blood pressure (≥10 mmHg) within 3 minutes of assumption of an upright position. Percentage of individuals that experienced orthostatic hypotension is indicated with shades of red; percentage of individuals that did not experience orthostatic hypotension is indicated with shades of gray. Among cervical SCI, prevalence of orthostatic hypotension was significantly lower in individuals with AIS A classification (5%) compared with AIS B (14%; p = 0.007) and AIS C (13%; p = 0.002)

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  Figure 2. Difference (1‐minute mean ± SD) in systolic blood pressure (mmHg, red vertical bars), diastolic blood pressure (mmHg, green vertical bars), and heart rate (BPM, yellow vertical bars) upon assumption of an upright position in individuals with SCI versus injury level (Panel a: AIS A; Panel b: AIS B; Panel c: AIS C; Panel d: AIS D). Vertical dashed lines delineate Cervical, High Thoracic, and Low Cord Injury groups with injury levels denoted on the x‐axis. Threshold for orthostatic hypotension is illustrated with horizontal dashed lines, defined by consensus statement (AAS/AAN, 1996) as a drop in systolic blood pressure (≥20 mmHg, dashed red line) or diastolic blood pressure (≥10 mmHg, dashed green line) within 3 minutes of assumption of an upright position. Profound blood pressure and heart rate changes occur within all AIS classifications and injury levels with the exception of those with AIS D low cord injury

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  Figure 3. Hierarchical cluster analysis based on change in systolic blood pressure, diastolic blood pressure, and heart rate upon assumption of an upright position. Dendrogram of individuals with SCI (Panel a) is ordered with similar hemodynamic responses having the least Euclidean distance between them. Difference (1‐minute mean ± SD) in systolic blood pressure (mmHg, red vertical bars), diastolic blood pressure (mmHg, green vertical bars), and heart rate (BPM, yellow vertical bars) upon assumption of an upright position were shown for each individual (Panels b and c). Vertical dashed lines delineate between clusters which are denoted as numbers on the top, with injury levels and severities denoted on the x‐axis (Panel b). Each non‐injured individual is denoted on the x‐axis (Panel c)