Fig. 4.
Ultrasound images of the radial artery cannulation. Examples of changes in the diameter and depth of the radial artery after subcutaneous injection and postcannulation. (A) A 3-month-old infant in the nitroglycerin group showed significant vasodilation after subcutaneous injection and maintained the increased diameter after cannulation. (B) A 1-month-old infant in the control group showed no change in the radial arterial diameter after subcutaneous injection. (C) Hematomas and (D) vasospasm after failed attempt. Long-axis images of (E) anterior arterial wall puncture, (F) posterior arterial wall puncture, (G) vasospasm proximal to the catheter tip, and (H) shadow by air bubble due to subcutaneous injection.