Table 2: Analysis of IJV cross-sectional diameters for each landmark point, with head in supine and head elevation at 30° (mean ± SD).

TopBottom
IJV diameter before cannulationIJV diameter after cannulation -valueIJV diameter before cannulationIJV diameter after cannulation -value

Head 0°R 0.36 0.41
L 0.09 0.29
Head 30°R 0.47 0.14
L 0.18 0.72