The anatomic relationship of femoral vein to femoral artery in euvolemic pediatric patients by ultrasonography: Implications for pediatric femoral central venous access

Background: Knowledge of the femoral vein (FV) anatomy in pediatric patients is important in the selection of appropriate size central line catheters as well as the approach to central venous access. This knowledge may avoid potential complications during central line access. Objectives: To describe the relationship of the FV to the femoral artery (FA). To measure FV diameter and FV depth using ultrasonography (US) in newborns, infants, and children up to 9 years of age. Methods: This study was a prospective descriptive study at a tertiary care children's hospital. A convenience sample of euvolemic children was enrolled aged 0-9 years presenting to an urban pediatric emergency department. All patients underwent a standardized US evaluation using a Sonosite Titan bedside machine by a single emergency physician. The FA and FV were identified by four criteria: relative positions, FV compressibility, FV enlargement by Valsalva maneuver, and absence of FV pulsatility. The position of the FV relative to the FA was described as being completely overlapped by the FA, having partial (< 50%) overlap by the FA, and having no overlap by the FA. The FV depth was measured from the skin to the superior border of the vein using the US machine's caliper function. Results: A total of 84 patients were studied. The FV was found to be completely overlapped by the FA in 8% of subjects and partially overlapped by the FA in 4% of subjects. The mean FV diameter ranged from 4.5 mm in young infants to 10.8 mm in patients 9 years of age. The mean FV depth ranged from 6.5 mm in neonates to 11.2 mm in patients 9 years of age. Conclusions: External landmarks were not always predictive of internal anatomy. The FV was completely or partially overlapped by the FA in 12% of cases. Thus, visualization of femoral vessels should be recommended prior to attempting pediatric femoral central venous access.