A meta-analysis in Anesthesiology confirms how central line cannulation is a lot safer when guided by ultrasound. Does that mean we don’t need blind landmark techniques?
Since a couple of years I am using real time ultrasound more and more when placing central lines. Initially I found it nice to have around as a rescue technique for tricky subclavians. Then I had my first full-on tension pneumothorax and almost killed an intubated patient. That totally spooked me and since all my central lines in intubated patients have been ultrasound guided.
Then, recently, I realised I am bringing the ultrasound with me for all central lines. Even for the electives. I am just not comfortable cannulating without it anymore. I still do the occasional blind cannulation, but only after getting an ultrasound overview of the anatomy. Now I noticed all of our baby registrars are doing virtually all their central lines, even IJVs, US guided. They don´t even bother to master the blind landmark technique. Similar thing with nerve blocks. No-one even knows where the nerve stimulator is anymore. Have we taken it too far?
It´s a meta-analysis of 26 RCTs and 4,185 individual cannulations comparing the classic landmark techniques with real time ultrasound guided cannulations (RTUS). Cannulations were IJV, subclavians and femoral veins. End-points were cannulation failure, arterial puncture, hematoma, pneumothorax and hemothorax. The review included pediatric cannulations, but by then the study was too underpowered to draw any conclusions.
RTUS cannulations were safer for all end-points. Compared with the control landmark technique relative risks for RTUS were
0,18 for cannulation failure…
0,25 for arterial puncture…
0,30 for hematoma…
0,10 for hemothorax and
0,21 for pneumothorax.
My take-home message
There is now solid evidence for how RTUS guided central lines are safer. RTUS significantly increases the cannulation success rate while the risk for pneumothorax, hemothorax, hematomas and arterial cannulation are reduced.
Still, blind techniques should be emphasised in teaching. There are plenty of scenarios where US does not do the job. We often end up with crap US imaging, due to individual anatomy, and succeed only after abandoning the US in favour of blind cannulation. Then there´s plenty of time critical situations where the US simply is not available.
The study lives here:
March 2013 – Volume 118 – Issue 3 – p 622–630.Real-time Two-dimensional Ultrasound Guidance for Central Venous Cannulation: A Meta-analysis. Wu, Shao-yong M.D.*; Ling, Quan M.D.†; Cao, Long-hui M.D., Ph.D.‡; Wang, Jian M.D.§; Xu, Mei-xi M.D.‡; Zeng, Wei-an M.D., Ph.D.‖