Fig. 2

Diagrams showing how to advance the needle into the radial artery using the DNTP technique. a, Obtain an image of the target artery and adjust the insertion point and orientation of the needle. b, Puncture the target artery, and observe the needle in the artery lumen. c, Advance the ultrasound probe away from the needle until the hyperechoic needle is no longer observed. d, Advance the needle and catheter until the very tip is seen again, and repeat these steps until the tip is observed in the artery lumen