Evaluation of the factors related to difficult ultrasound-guided radial artery catheterization in small children: A prospective observational study

Background: Although ultrasound guidance has significantly improved the success rate of radial artery catheterization, the failure rate in children is still high. For the further improvement of success rate, we prospectively evaluated the factors that make ultrasound-guided radial artery catheterization difficult in children under two years old. Methods: From October 2018 to September 2019, patients who required radial artery catheterization for surgery were enrolled. After collecting the anatomical characteristics of the radial artery using ultrasound at the puncture site, ultrasound-guided radial artery catheterization was performed by one experienced anaesthesiologist. The primary outcome was to identify the factors related to the first attempt failure. The factors associated with the total duration of the procedure until success were also evaluated. Results: A total of 183 children were included in the analysis. A radial artery cross-sectional area of ≤1 mm² (odds ratio [OR] = 5.26; 95% confidence interval [CI], 2.48-11.18; P <.0001) and the presence of an anomalous radial artery branch (OR = 3.37; 95% CI, 1.43-7.95; P =.005) were independent predictors of first-attempt failure during ultrasound-guided radial artery catheterization. The total procedure time was also negatively associated with the small cross-sectional area (P <.001). Conclusions: A cross-sectional area of ≤ 1 mm² and the presence of an anomalous branch of radial artery significantly increased the difficulty of ultrasound-guided radial artery catheterization in children under two years old. In patients of these ages, pre-procedural ultrasound scanning to find an optimal site for catheterization may increase the first-attempt success rate although further studies are needed to verify our results. Trial Registration: Clinical Research Information Service (https://crits.nih.go.kr, October 6, 2018 [KCT0003239]; Principle investigator: Jong-Hwan Lee).