Fig. 6
From: Ultrasound-guided peripheral venous cannulation in critically ill patients: a practical guideline
Explaining the distance from skin to vessel in ultrasound-guided cannulation. While this distance (d) is estimated in the short axis, the real distance to reach the vein depends on the insertion angle. Assuming a 45° insertion angle, this real distance is equal to d multiplied by 1.4. Of note, the real distance decreases with sloped insertions, and increases using shallower insertions