Size of internal jugular vs subclavian vein in small infants: an observational, anatomical evaluation with ultrasound.

BACKGROUND: The primary goal of this study was to compare the size and depth of the internal jugular vein (IJV) and the subclavian vein (SCV) in infants under general anaesthesia. A secondary goal was to determine the correlation of weight, height, head circumference, and age to the size and depth of these veins.

METHODS: Sixty small infants weighing from 1.4 to 4.5 kg were included. Using ultrasound, the diameters via short-axis (SAX) and long-axis (LAX) views, cross-sectional area (CSA), and depth of the left and right IJV and SCV were measured.

RESULTS: The diameter of the IJV was 7.9% larger on average than that of the SCV as measured via the SAX and LAX views (mean: 3.1 vs 2.9 mm; Wilcoxon's signed-rank test: P<0.01). The CSA of the IJV was 27% larger on average than that of the SCV (mean: 10.2 vs 8.0 mm(2); Wilcoxon's signed-rank test: P<0.01). Seventy-five per cent of the neonates showed a larger CSA of the IJV. The SCV was 8.4% deeper on average from the skin surface than the IJV (mean: 6.4 vs 5.9 mm; Wilcoxon's signed-rank test: P<0.01). There was a significant positive correlation between weight, height, head circumference, and age to the size and depth of the veins (Spearman's rank correlation: P<0.01).

CONCLUSIONS: Because of its most likely larger size, the IJV can be recommended as the better choice for cannulation in comparison with the SCV. However, other factors should also be considered.