The rate of successful first attempts did not differ significantly between either of the 2 intervention groups and the standard approach group ( differences in proportions -3.9 % , 95 % confidence interval [ CI ] -14.2 % to 6.5 % , for ultrasound imaging ; -8.7 % , 95 % CI -19.4 % to 1.9 % , for near-infrared imaging ) .