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Table 1 Key concepts for ultrasound-guided peripheral venous cannulation

From: Ultrasound-guided peripheral venous cannulation in critically ill patients: a practical guideline

Key concept



Must know

Basic general knowledge for ultrasound-guided vascular cannulation

Selection of the transducer and preset; image orientation; basic image optimization; distinguishing veins versus arteries; managing techniques of cannulation (out-of-plane and in-plane technique)


Select superficial veins (i.e., epifascial)

Superficial veins: short pathway to reach the vein; high probability that a great proportion of the catheter will dwell in the vein

Deep veins: inherent risks of needle-stick injury of the artery or the nerve; frequent catheter dislodgment


Patent veins

Anechoic lumen; fully compressible

Do not misinterpret stagnant blood in the vein lumen with thrombus (distal compression is useful)


Vein size: anteroposterior diameter ≥ 4 mm

AP diameter (mm) = maximum Fr catheter size

(e.g., 4 mm = up to 4-Fr catheter)


Vein depth: up to 16 mm (short axis)

Real distance to reach the vein (45° insertion angle)*: 1.4 × vertical distance

*Ideally measure real distance in long axis and select the best angle of insertion

≥ 2.75 cm of the catheter must dwell in the vein

Consider using ultra-long peripheral (6.3 cm) and midline (8–20 cm) catheters to minimize catheter failure


Select the technique: in-plane or out-of-plane technique

Both are useful, although it seems to be a greater success rate with the out-of-plane technique

Learning and using both techniques is encouraged


Checking catheter position

Direct: double hyperechoic line into the lumen vein

Indirect: saline flush test (two-dimensional and/or color Doppler)