Peripheral intravenous cannulation using ultrasound guidance is commonly used for veins not amenable to discovery by the traditional methods of palpation and visualization. Using ultrasound decreases complications such as pain, and increases the likelihood of successful vascular access with first attempt.

Shown in this case was an in-plane technique, which allows real-time visualization of the needle in long-axis as one advances it through the superficial tissues and into the vessel lumen. Two other techniques exist, the other commonly used variant being the short-axis, or "out of plane" technique, which visualizes the target vessel as shown above initially. One will then advance the needle a short distance, advance the probe until the needle is no longer visualized, advance the needle until it is visualized, and repeat the process, thereby ensuring one is visualizing the tip of the needle. Once the anterior wall is indented, a swift push will introduce the needle into the lumen, which may be visualized as a hyperechoic dot in the anechoic vessel ³.

A newer technique is the use of the oblique, "transverse-oblique" or "medial-oblique," axis; achieved by rotating 45 degrees from a transverse orientation and advancing the needle in-plane, it offers the ability to dynamically visualize the needle and target while also monitoring surrounding structures, the latter lauded as an advantage of the short-axis technique and the former only possible with the long-axis. It also may offer a wider diameter target for cannulation ⁴.

Regardless of method, confirmation within the vessel is crucial to avoid complications such as extravasation of infusate. The saline flush test, as pictured above, provides direct evidence that the catheter is within the lumen of the vessel and is patent. 

Learning Points:

• common methods used for peripheral IV insertion with ultrasound include the out-of-plane, short-axis and the in-plane, long-axis techniques
• the short-axis technique allows greater visualization of surrounding structures
  • posterior wall puncture is more frequent with this technique ²
• the long-axis technique allows real-time visualization as the needle enters the lumen
  • off-axis imaging may result in inadvertent cannulation of a nearby artery, which may look almost identical
• the oblique-axis technique is a new, real-time technique which proponents claim to offer the advantages of the aforementioned alternatives
• regardless of technique, confirmation that the target vessel is venous, controlled intra-luminal entry, and confirmation of intravascular placement prior to use all remain key principles of ultrasound guided peripheral access