Table 2.
Internal carotid artery hemodynamic parameters in the supine position and during head-up tilt.
| Side | Parameter | Supine | Tilt 1 min | p | Tilt 5 min | p |
|---|---|---|---|---|---|---|
| Right | PSV (cm/s) | 68.2 ± 19.3 | 67.9 ± 19.1 | 0.885t | 68.5 ± 19.9 | 0.848t |
| Right | EDV (cm/s) | 26.9 ± 8.7 | 23.5 ± 8.0 | <0.001t | 22.5 ± 7.8 | <0.001t |
| Right | TAMEAN (cm/s) | 29.6 ± 9.8 | 25.9 ± 8.8 | <0.001t | 25.9 ± 8.1 | <0.001t |
| Right | Diameter (mm) | 5.09 ± 0.54 | 5.11 ± 0.58 | 0.477w | 5.12 ± 0.57 | 0.509w |
| Right | Volume flow (mL/min) | 352.7 ± 138.0 | 319.7 ± 129.6 | 0.004t | 317.2 ± 124.2 | 0.002t |
| Left | PSV (cm/s) | 68.4 ± 16.7 | 70.2 ± 20.1 | 0.309t | 70.4 ± 20.8 | 0.244t |
| Left | EDV (cm/s) | 26.5 ± 6.3 | 24.1 ± 6.8 | <0.001w | 23.6 ± 7.5 | <0.001t |
| Left | TAMEAN (cm/s) | 28.6 ± 7.0 | 26.4 ± 7.0 | 0.002w | 26.7 ± 8.2 | 0.010w |
| Left | Diameter (mm) | 5.16 ± 0.62 | 5.14 ± 0.57 | 0.897w | 5.17 ± 0.56 | 0.363w |
| Left | Volume flow (mL/min) | 363.4 ± 79.2 | 322.7 ± 85.5 | <0.001t | 331.6 ± 94.0 | 0.008t |
| Right | ΔICA (%) | – | 7.3 ± 21.0 | – | 8.1 ± 20.4 | – |
| Left | ΔICA (%) | – | 10.6 ± 16.2 | – | 8.0 ± 19.0 | – |
Values are mean ± SD (n = 41). p values compare each tilt time point with the supine measurement. tPaired t-test; wWilcoxon signed-rank test, used when the distribution of differences deviated from normality. PSV, peak systolic velocity; EDV, end-diastolic velocity; TAMEAN, time-averaged mean velocity. ΔICA denotes the percentage reduction in volume flow from the supine value at each time point, calculated for each patient; negative values indicate an increase, and no supine-versus-tilt comparison applies. The maximum of the four ΔICA values, used for group classification, was 23.4 ± 15.2% overall: 32.4 ± 9.7% in Group A and 7.8 ± 8.9% in Group B.