Background: We evaluated the posterior tibial artery as an alternative arterial cannulation site to the radial artery in small children.

Methods: A two-stage study was conducted. First, we evaluated the anatomical characteristics of the posterior tibial artery compared with the radial and dorsalis pedis arteries. Next, a parallel-arm single-blind randomized controlled study compared the initial success rate of ultrasound-guided arterial cannulation among three arteries as a primary outcome.

Results: Sixty patients were analyzed in the observational study. The diameter of the posterior tibial artery (1.5 ± 0.2 mm) was similar to that of the radial artery (1.5 ± 0.2 mm) and larger than that of the dorsalis pedis artery (1.2 ± 0.2 mm; P < 0.001). The posterior tibial artery has a larger cross-sectional area (2.8 ± 1.1 mm²) compared with the radial (2.3 ± 0.8 mm²; P = 0.013) and dorsalis pedis arteries (1.9 ± 0.6 mm²; P = 0.001). In total, 234 patients were analyzed in the randomized study. The first-attempt success rate of the posterior tibial artery (75%) was similar to that of the radial (83%; P = 0.129; odds ratio, 1.53; 95% CI, 0.69 to 3.37) and higher than that of the dorsalis pedis artery (45%; P < 0.001; odds ratio, 3.95; 95% CI, 1.99 to 7.87). Median cannulation time of the posterior tibial artery (21 s; interquartile range, 14 to 30) was similar to that of the radial artery (27 s; interquartile range, 17 to 37) and shorter than that of the dorsalis pedis artery (34 s; interquartile range, 21 to 50).

Conclusions: The posterior tibial artery is a reasonable alternative to the radial artery for ultrasound-guided arterial cannulation in small children.