To the Editor:
We read the article by Auyong et al.1 and have a few questions/comments about the study.
It is interesting to note that the authors did not observe any significant difference in the incidence of posterior wall (PW) puncture with respect to the years of experience of the provider. There also appears to be no association between the frequency of ultrasound procedures performed or supervised and the incidence of PW puncture. We noted that the academic practice was found to be somewhat protective toward the PW puncture.
We wondered why the authors counted a pass as any needle withdrawal of greater than 0.5 cm and how this was monitored, especially in the group with the navigation off. We would suggest that this distance be approximately 1 cm, as the internal jugular vein (IJV) was 1.1 cm below the skin. Vogel et al.2 defined redirections as changes in the direction of the needle after insertion without removing it from the skin. In addition, to reconsider the distance of needle withdrawal to closely and accurately monitor the number of passes, we would suggest marking the introducer needle to measure the distance of the needle as it is introduced. Reconsidering the distance required to qualify as a pass and marking the introducer needle could have influenced the observed number of passes and may have affected the results of the study.
There are a few techniques we practice at our institution for ultrasound-guided central venous catheterization. An ultrasound examination is performed before prepping and draping the site of venous cannulation, and the depth of the vein from the skin is noted. Marking the introducer needle based on the depth of IJV as observed on the preprocedural ultrasound may prevent inadvertent insertion of the needle beyond the lumen of the vein and could possibly decrease the incidence of PW puncture.3 After successful cannulation of the IJV with the introducer needle and subsequent insertion of the guidewire via the introducer needle, inadvertent penetration of the PW of IJV or carotid artery may occur during the process. It may be prudent to confirm the location of the guidewire within the vein to avoid complications.4,5
The authors used the out-of-plane technique to compare the incidence of PW and carotid artery puncture. We would suggest using the in-plane technique because the needle can be seen along the entire length as it is introduced into the vein.3,6 Vogel et al.2 observed that the long-axis view for IJV cannulation was more efficient than the short-axis view and was associated with a significantly decreased number of redirections during IJV cannulation. The in-plane use of the ultrasound probe could possibly have decreased the number of passes, the incidence of PW, and subsequent carotid artery puncture, especially in the group with navigation off, and may have altered the results of the study. Alternatively, a medial-oblique approach of the ultrasound probe may be used to possibly decrease the risk of PW penetration.
Departmental support was received by the authors for this work.
The authors declare no competing interests.