In-plain versus out-of-plain ultrasound guidance technique for neonatal vascular access: a randomized crossover study.

Background and aim: Ultrasound guidance for vessel cannulation has emerged as a key tool in pediatric and in neonatal care. There are two techniques for ultrasound guided (US) vessel cannulation: the long-axis in-plain (LA-IP) approach and the short-axis out-of-plain (SA-OOP) approach. Each technique has its own benefits and drawbacks. Several studies aimed to investigate the best approach, with no firm consensus. The aim of this study was to determine whether the SA-OOP or the LA-IP is the best approach for US-guided cannulation of small caliber vessels performed by “naïve” doctors on a vascular phantom. Methods: Thirty-one pediatric residents were eligible to participate. Under US guidance, participants were asked to attempt the cannulation of both a small (internal diameter 2mm) and a large (internal diameter 4mm) caliber phantom vessel using both SA-OOP and LA-IP approaches. The following data were recorded: 1) number of attempts for successful cannulation, 2) insertion time. The primary outcome was the number of failed attempts for each cannulation technique. Secondary outcomes included successful puncture on the first attempt and the time of insertion. Results: The SA-OOP approach showed lower failure rates compared to the LA-IP technique in the 2mm diameter vessel (p=0.002). A trend toward lower rates of failed attempts was observed also for the 4mm vessel using the SA-OOP approach but with no statistical significance (p=0.124). The number of successful cannulations on the first attempt using the SA-OOP approach was higher both in the 2mm (p=0.0015) and 4mm diameter vessel (p=0.057), in the latter with no statistical significance. No significant difference was observed in terms of cannulation time between the two approaches in both diameter vessels. Conclusion: This study demonstrates that the US-guided technique for vessel cannulation is feasible in pediatric residents naïve to the technique. The results show a significantly lower number of failed attempts, with a greater number of successful cannulations at first attempt, using the SA-OOP approach in a 2 mm caliber vessel on a phantom. The difference between the two approaches in a 4mm vessel was not significant. No significant difference was observed in terms of cannulation time.