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1-Plane, 2-Plane, X-plane? Ultrasound-Guided Central Lines

October 11, 2023

Written by Samuel G. Rouleau

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In a small, randomized trial, placing an ultrasound-guided central venous catheter (CVC) using 2 planes simultaneously was more likely to be successful on the first attempt and performed more quickly. Both groups had a 100% procedural success rate.

More piezoelectric crystals, more planes, same outcome?
Over 15 million CVCs are placed per year in the United States. The implementation of ultrasound-guided CVC placement has reduced complications and improved the safety of this procedure. The two main methods are out-of-plane (short axis) and in-plane (long axis), and there are no data to suggest that one is approach is superior to the other. But…what if you could use both views simultaneously?

Researchers in China designed a single-center, randomized trial comparing the “x-plane” technique to the in-plane (long axis) approach. The x-plane technique, using the EPIQ system, with XL14-3 probe, uses real-time 3-dimensional imaging to create the transverse (short axis) and longitudinal (long axis) views simultaneously. 256 patients were included, 128 randomized to each group with similar age, height, weight, and BMI in each group. The supervising physician on the care team, who was not part of the study, determined if the patient would undergo CVC insertion to the internal jugular vein (IJV) or the femoral vein (FV). There were 5 proceduralists who had been trained for 3 months prior to the study.

Figure 2, taken directly from the paper, shows the single-plane approach in the top row and the x-plane approach in the bottom row.

From cited article

My takeaway is that CVC placement was 100% successful in each group, and there were no occurrences of arterial puncture, pneumothorax, or hemothorax during CVC placement into the IJV in either group. Interestingly, there were 5 occurrences of femoral artery puncture in the in-plane only group and 0 in the x-plane group, though this difference was not statistically significant. The x-plane group had a higher rate of IJV first-puncture success: 91.6% vs 74.7%, RR 1.226 (95%CI 1.069-1.405), fewer puncture attempts, and shorter puncture time by approximately 30 seconds. For CVC placement in the FV, outcomes were similar. The only complication that was statistically significant between both groups was “undesired puncture,” meaning the single-plane group had more incidents of having to remove the needle tip from the skin to redirect needle trajectory.

How will this change my practice?
The short answer is it won’t, but I would love to try the technology because it looks cool! As an ultrasound nerd and someone who appreciates procedural micro skills, I have a lot of thoughts on this paper, which I’ve decided to list in bullet form.

  • Kudos to the authors for undertaking a randomized trial, in real, critically ill patients.
  • The operators were inexperienced, with only 3 months of training, which shows in the low first-pass success rates.
  • So, my interpretation of this study’s results are: If I wanted to maximize the success of an individual who has little or no experience in performing CVC placement, they will perform better if I give them more information (2-views simultaneously versus 1-view), which is really not surprising.
  • When I place a central line, I never limit myself to only one view. I use both short and long-axis to assess the vessel, monitor my needle tip if having any difficulty, and confirm wire placement. Also, the patient’s anatomy will greatly affect what approach I rely on, so limiting the operators in this study to only the long-axis view is problematic.

Single-plane versus real-time biplane approaches for ultrasound-guided central venous catheterization in critical care patients: a randomized controlled trial. Crit Care. 2023 Sep 23;27(1):366. doi: 10.1186/s13054-023-04635-y.

What are your thoughts?