Fig. 5
From: Ultrasound-guided peripheral venous cannulation in critically ill patients: a practical guideline
Distance from skin to vein for US-guided cannulation. In a, it is < 12 mm (ideal), while in b is > 16 mm. Since the vein in b has a diameter > 4 mm, it could still be cannulated using longer catheters than usual, for example, a midline catheter