Ultrasound-guided peripheral intravenous cannulation

Peripheral intravenous cannulation under ultrasound guidance is the placement of a cannula into a peripherally-located vein under the direct vision of ultrasound. This process allows the cannulation of veins that are unable to be visualized or palpated without ultrasound. In trained individuals this method of cannulation results in higher first-pass and overall success rates with fewer complications.

• There are, in general, 2 views used in ultrasound-guided peripheral venous cannulation. The short-axis (transverse, cross-sectional) view usually is preferred because it is easy to obtain and is the best view for identifying veins and arteries and their orientation to each other. However, the transverse view shows the needle only in cross-section (hyperechoic [white] dot), and the needle tip can be distinguished only by the appearance and disappearance of the white dot as the imaging plane traverses past needle tip.

TRANSVERSE

• The long-axis (longitudinal, in-plane) ultrasound view is technically more difficult to obtain (must keep probe, vein, and needle in one plane), but the entire needle (including the tip) is imaged continuously, which ensures accurate intraluminal placement. Increasing narrowness of peripheral veins increases the difficulty of obtaining the longitudinal view.

LONGITUDINAL

Peripheral veins may be superficial or deep. Typically, ultrasonographic guidance is needed when superficial veins are not visible or palpable. Typical targets for ultrasound-guided IV placement include

• Deep forearm veins

• The brachial vein (there are typically 2 brachial veins that lie on either side of the brachial artery in the medial upper arm)