It was with great interest that we read the article ‘Short-axis/out-of-plane or long-axis/in-plane ultrasound-guided arterial cannulation in children’ by Song et al.1 Research in this expanding clinical field is important and we would like to praise the authors for conducting a nicely designed study.
However, we are truly worried about the posterior wall puncture rate of almost 100% when applying the short-axis technique.
In the present study, posterior wall puncture rate was 95.7% for the short-axis technique compared with the 18.0% of the long-axis technique. The high posterior wall puncture rate indicates that the operators performed the short-axis technique insufficiently. The deciding strength of the short-axis technique is that while the artery appears as an anechoic (black) structure on the monitor, the needle (tip) is visualised as a hyperechoic (white) dot that can easily be tracked accurately to the target vessel. The high posterior wall puncture rate put forward clearly shows that the operators did not identify and track the needle tip dynamically. Hence, the full potential of the short-axis technique was not utilised and the consequence was an unnecessary and unacceptable rate of posterior wall puncture.
We agree that ultrasound guidance for vascular access is rightfully gaining popularity and it is a great tool to increase the success rate. However, it is important to understand that the benefit of ultrasound guidance strongly depends on the operator's skills. In the present study, the paediatric anaesthesiologists were presumably sufficiently skilled, as they had performed more than 20 ultrasound-guided arterial cannulations. However, this premise proved erroneous and we advocate that a formalised educational programme or test should be required prior to study initiation.
A lack of optimal technique was further demonstrated by the low first attempt success rates (short-axis, 58.0% versus long-axis, 54.9%). Similar paediatric studies have shown higher first attempt success rates including Schwemmer et al.2 (67.0%) and Ishii et al. (76.3%).3
We have shown very promising results of the short-axis technique approach named the dynamic needle tip positioning (DNTP)4 for radial artery catheterisation in adults.5 We believe similar results can be obtained in children if the technique is mastered sufficiently. Nevertheless, superficial vessels in children are often put forward as a challenge for tracking the needle into the target vessel. We have recently described a technique for cannulation of superficial vessels termed DNTP - para vessel approach, which may be helpful for operators with limited ultrasound experience.6
Acknowledgements relating to this article
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1. Song IK, Choi JY, Lee JH, et al. Short-axis/out-of-plane or long-axis/in-plane ultrasound-guided arterial cannulation in children: a randomised controlled trial. Eur J Anaesthesiol
2. Schwemmer U, Arzet HA, Trautner H, et al. Ultrasound-guided arterial cannulation in infants improves success rate. Eur J Anaesthesiol
3. Ishii S, Shime N, Shibasaki M, Sawa T. Ultrasound-guided radial artery catheterization in infants and small children. Pediatr Crit Care Med
4. Clemmesen L, Knudsen L, Sloth E, Bendtsen T. Dynamic needle tip positioning: ultrasound guidance for peripheral vascular access. A randomized, controlled and blinded study in phantoms performed by ultrasound novices. Ultraschall Med
5. Hansen MA, Juhl-Olsen P, Thorn S, et al. Ultrasonography-guided radial artery catheterization is superior compared with the traditional palpation technique: a prospective, randomized, blinded, crossover study. Acta Anaesthesiol Scand
6. Sloth E, Gopalasingam N, Obad DS, et al. Dynamic needle tip positioning-para vessel approach. Paediatric Anaesth