Table 2.
Mean values ± standard deviation of frequency domain parameters reflecting powers of autonomic modulation of RR intervals and blood pressure, and baroreflex sensitivity in supine and in standing positions in 20 patients with a history of mild TBI, 20 patients with a history of moderate or severe TBI (moderate–severe TBI) and 20 healthy controls
| Parameter | Position | Healthy controls (n = 20) | Mild-TBI patients (n = 20) | Moderate–severe TBI patients (n = 20) | Mild TBI vs. controls | Moderate–severe TBI vs. controls | Mild TBI vs. moderate–severe TBI |
|---|---|---|---|---|---|---|---|
| LF-RRI powers (ms2) | Supine | 2650.3 ± 4336.0 | 1881.2 ± 1983.0 | 1939.2 ± 1832.4 | P = 0.841 | P = 0.583 | P = 0.534 |
| Standing | 1319.8 ± 1292.7 | 1123.6 ± 1247.6 | 1725.7 ± 3056.0 | P = 0.640 | P = 0.478 | P = 0.547 | |
| LFnu-RRI powers (%) | Supine | 49.6 ± 14.3 | 61.2 ± 15.9 | 71.4 ± 8.9 | P = 0.020 | P = 0.000 | P = 0.017 |
| Standing | 80.8 ± 12.5 * | 79.2 ± 15.2 * | 83.2 ± 13.9 * | P = 0.728 | P = 0.369 | P = 0.395 | |
| HF-RRI powers (ms2) | Supine | 1837.4 ± 1935.3 | 1117.1 ± 1232.6 | 702.5 ± 691.0 | P = 0.157 | P = 0.018 | P = 0.534 |
| Standing | 292.8 ± 314.1 * | 313.3 ± 466.8 * | 515.9 ± 1248.2 | P = 0.640 | P = 0.277 | P = 0.678 | |
| HFnu-RRI powers (%) | Supine | 50.4 ± 14.3 | 38.8 ± 15.9 | 28.6 ± 8.9 | P = 0.020 | P = 0.000 | P = 0.017 |
| Standing | 19.2 ± 12.5 * | 20.8 ± 15.2 * | 16.8 ± 13.9 * | P = 0.728 | P = 0.369 | P = 0.395 | |
| LF/HF-RRI ratios | Supine | 1.4 ± 0.7 | 2.7 ± 2.6 | 3.8 ± 2.8 | P = 0.072 | P = 0.000 | P = 0.194 |
| Standing | 8.2 ± 9.5 * | 7.1 ± 6.3 * | 11.3 ± 11.1 * | P = 0.883 | P = 0.369 | P = 0.279 | |
| LF-BPsys powers (mmHg2) | Supine | 15.0 ± 8.5 | 14.4 ± 12.1 | 18.8 ± 14.8 | P = 0.429 | P = 0.799 | P = 0.301 |
| Standing | 27.1 ± 20.3 * | 24.4 ± 25.8 | 35.5 ± 32.2 | P = 0.214 | P = 0.512 | P = 0.089 | |
| HF-BPsys powers (mmHg2) | Supine | 1.8 ± 1.2 | 2.1 ± 1.4 | 2.1 ± 1.9 | P = 0.602 | P = 0.718 | P = 0.862 |
| Standing | 7.4 ± 1.3 * | 6.2 ± 5.3 * | 10.5 ± 13.6 * | P = 0.309 | P = 0.738 | P = 0.509 | |
| BRS | Supine | 13.8 ± 8.3 | 11.1 ± 4.8 | 10.8 ± 5.8 | P = 0.461 | P = 0.221 | P = 0.583 |
| Standing | 6.2 ± 3.6 * | 5.8 ± 3.3 * | 5.6 ± 5.7 * | P = 0.813 | P = 0.369 | p = 0.411 |
RRI RR interval, BPsys systolic blood pressure, LF low frequency, LFnu normalized LF powers, HF high frequency, HFnu normalized HF powers, BRS baroreflex sensitivity
An asterisk (*) indicates a significant difference (P < 0.05) between supine and standing values
Significant differences between groups are indicated in bold and underlined for the parameters, and in bold underlined italics for the P-values