Ultrasound-Guided Peripheral Vascular Catheterization in Pediatric Patients: A Narrative Review

Background

Peripheral vascular catheterization (PVC) is an essential skill for healthcare providers caring for patients in the perioperative, intensive, and emergency departments. In small children this procedure can be very challenging. In difficult cases, ultrasound-guidance PVC placement can be very useful.

In pediatric patient population, the utility of ultrasound-guided approach of PVC placement has been demonstrated in numerous studies, showing improved success rate, procedure time, number of attempts, and number of complications. In neonates, infants and small children, ultrasound guidance in radial arterial catheterization increases the first-attempt rate.

However, ultrasound-guided PVC remains challenging for less-experienced operators, and the purpose of this narrative review is to summarizes the accumulated knowledge and experiences to aid and improve ultrasound-guided PVC in pediatric patients.

Arteries in the upper extremities

The radial and ulnar arteries are the two major branches of the brachial artery and supply blood to the forearm and the hand. Ultrasound-guided radial arterial catheterization has been most studied, mostly because it has collateral circulation with the ulnar artery, has less anatomic variation, and has a low complications rate. Numerous studies have confirmed the utility of ultrasound guidance at this site in pediatric and adult patients.

Arteries in the lower extremities

Alternatives to the radial arteries include the posterior tibial and dorsal pedis arteries. For example, one study demonstrated that first-attempt success rate, catheterization time, and arterial diameter of the posterior tibial artery was similar to those of the radial artery. In contrast, the dorsal pedis artery was associated with a lower first-attempt success rate, longer catheterization time, and smaller arterial diameter than the radial and posterior tibial arteries.

Peripheral venous catheterization: Veins in the upper and lower extremities

The dorsum of the hands or feet are the most common peripheral intravenous access site, although these veins are often invisible and impalpable in pediatric patients, leading to 8–50% of catheterizations determined to be difficult venous access.

Since the vein diameter is an independent predictor of successful catheterization, the saphenous vein at the medial malleolus or the cephalic vein at the forearm is suggested to be the preferable site for ultrasound-guided PVC placement.

While veins at the cubital fossa are considered to have sufficient venous diameter and depth, they could be alternative access sites in cases of prior unsuccessful catheterization in other areas. Nonetheless, there appear to be no reports of ultrasound-guided catheterization of these veins and there is also a risk of inadvertent puncture of the brachial artery. Lastly, when the elbow is bent, the catheter may not work.

The major approaches for ultrasound guidance

Long axis view (LAX) and short-axis (SAX) views are the two planes of target vessel visualization in ultrasound guidance.

Terminology:

In plane (IP) approach: IP approach refers to the movement of the catheter on the ultrasound plane while the catheter shaft is visualized as it is advanced toward the vessel.
Out of plane (OOP) approach: With OOP approach, the catheter and ultrasound plane are at right angles to each other and only the needle tip is visualized on the screen.

The IP approach occurs when the LAX view is used (LAX-IP) and the OOP approach occurs when the SAX view is used.

While in adult population the SAX-OOP approach has been shown to have higher success rate than the LAX-IP approach, in pediatric patients there is controversy regarding which approach is superior for guidance of placement of peripheral venous catheters. Therefore, the operator should be familiar with the advantages and disadvantages of each approach.

Dynamic needle tip positioning

Dynamic needle tip positioning (DNTP) has been derived from the «static» SAX-OOP approach, where the operator traces the needle tip by sweeping the probe akin to making a flip cartoon of the catheterization in the SAX-OOP approach.

The authors conclude the manuscript by describing the pitfalls, artifacts and providing diagrams that demonstrate the concepts describe in the paper.