To the Editor:
We read with interest the report by Quan et al. of a novel acoustic shadowing technique for pediatric arterial cannulation—a technically difficult procedure even for experts.1 The first-pass success rate of 60% by experienced providers (with more than 50 ultrasound-guided cannulations) in their report in 9 ± 3-month-old children for the traditional ultrasound group seems low, but is consistent with previously published data.2,3
The authors choose to use procedural times as a secondary outcome, which we believe is a misleading metric in this context. The authors state that the decreased time to ultrasound localization of the artery (18 s vs. 4 s) and decreased time to arterial puncture (40 s vs. 24 s) demonstrate an efficiency advantage and time savings compared to traditional ultrasound utilization. A more accurate representation of the true impact on efficiency and timeliness would incorporate setup time for the novel technique, which we strongly suspect would outweigh the clinically insignificant (30 s total) time savings the authors report. In the pediatric critical care setting, trainee first-pass success utilizing ultrasound guidance has been reported at 28%, with an average total procedure time of 8.1 min.4 Reduction in procedural time may be a more valid outcome measure among less experienced practitioners than in the context in which the authors found such minimal change. As educators, we would be interested in seeing the impact of this novel intervention on trainee performance and cumulative sum learning curves, and we encourage the authors to continue to investigate this issue.
The authors declare no competing interests.