Kaplan–Meier estimates for the overall procedure time to successful cannulation of the chosen radial artery within two attempts and 10 min (nitroglycerin vs. control group, P < 0.0001). The median cannulation time of the chosen radial artery was 37 s (interquartile range, 25 to 53 s) in the nitroglycerin group and 57 s (interquartile range, 37 to 168 s) in the control group.