Margin of safety for needle puncture of a radial artery in children: Recommendation for ultrasound-guided cannulation.

Background: The radial artery is commonly selected for arterial puncture and cannulation, but radial nerve palsy may occur. To minimize possible damage to the nerve, needle puncture should be made within the margin of safety (between the wrist to the distal end of the radial artery and the radial nerve running in parallel). In adults, the margin of safety for radial artery puncture is approximately 6.8 cm from the wrist in men and approximately 5.4 cm in women, but the margin of safety is not known in children of different age groups.

Methods: Using an ultrasound device, we measured the margin of safety in 100 anesthetized patients aged 0 months to 15 yr. Polynomial quadratic regression models were made, and the lower limit of the prediction interval was regarded as the margin of safety. These results were then compared with the results obtained in adults.

Results: The margin of safety became wider as a child grows older, and the height, weight, and age were all suitable explanatory variables to predict the margin of safety, providing fairly a constant predicted margin of safety from a few millimeters in neonates to approximately 4 cm in adolescents (much narrower than in adults).

Conclusions: In children and adolescents, the margin of safety for radial artery puncture is much narrower than in adults, and these findings support the recommendation to use ultrasound guidance during radial artery puncture in children and adolescents, to minimize the risk of associated complications.

Clinical trial registration: jRCT1032230243.