Deep Needles and Shallow Veins. Ultrasound Estimation of Internal Jugular Mid-Vein and Posterior Wall Depth During Central Line Placement in Trendelenburg Position

Background Central line placement is a very common inpatient procedure and the internal jugular (IJ) vein is the most commonly accessed site. Complications associated with this procedure include pneumothorax, hemothorax and pain which may be caused by accidental visceral injury with needle over-penetration. Research Question Extrapolating approximate needle length required to access sonographic mid-point of the internal jugular (IJ) vein. Study Design Retrospective, non-randomized, non-blinded study. Method Retrospective review of IJ vein images taken during central line placement to determine skin to mid-vein and skin to posterior wall depth in Trendelenburg position . Pooled data of IJ vein images taken with ultrasound probe perpendicular to skin during non-emergent/non-ICU central line placement from 12/01/2016 to 11/30/2019 (3years) was retrieved from a secure database. Images, biological sex and BMI were reviewed. Inclusion criteria: all IJ vein images. Exclusion criteria: Non- IJ vein images. Vein depth measurements were estimated using the depth marker grid accompanying the images. Results Primary end point: average skin to mid-vein and skin to posterior wall depths. Secondary end point: compare the same dimensions based on biological sex and BMI . 608 images were analyzed. 375 were suitable (244 male [65%], 131 female [35%]). 233 poor quality images were discarded. Average skin to mid-vein depth for females was 1.47 cm (±0.37 SD, range 0.8-2.6 cm), for males 1.48 cm (±0.35 SD, range 0.8-2.7 cm) and for the total population 1.48 cm (±0.35 SD, range 0.8-2.7 cm). Average skin to posterior wall depth for females was 2.07 cm (±0.5 SD, range 1.2 cm-3.6 cm), for males 2.09 cm (±0.47 SD, range 1.3-3.3 cm) and for the total population 2.08 cm (+/0.48 SD, range 1.2-3.6 cm). Skin to IJ vein depths were normally distributed with similar standard deviations when compared for biological sex or total population. Adjusting for BMI, males were found to have a 0.2 cm increase in skin to mid-vein depth and a 0.12 cm increase in skin to posterior wall depth compared to females. Conclusion The needle length required to reach the average sonographic midpoint of the IJ vein is approximately 1.48 cm with a range of 0.8 to 2.7 cm. As ultrasound does not intrinsically prevent needle over insertion, proceduralists, particularly less experienced operators, need to be mindful of needle depth to reduce complications from excessive needle tip penetration.