CVC AND US

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?

Background
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?

The study
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.

Results
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.

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8 Responses to CVC AND US

  1. nfkb says:

    in our department we unfortunately lack of US devices. Only one for 14 OR 🙁 so sometimes we have to put the line without echo. money money money…

  2. K says:

    Remy, where I work several of my colleagues are echo freaks. That and an extremely high rate of…ummm…. ´management turnover´ has resulted in us having I think 10 US machines to be shared by 30 docs. We really have no excuses for not having an US nearby.

  3. Rahul says:

    It is going too far. What happens when the U/S is being used by another? Or malfunctioning/being serviced?

    I personally teach residents and regs to scan the anatomy and go blind at least once in their rotation. Cos the ability to go on “when things go wrong” is what defines us as ED physicians.

  4. toby says:

    It is easy to come up with several scenarios where you will have to place a central line without an ultrasound machine. Thus it is important not to de-skill. On the other hand, it is difficult to defend attempting to place a line “blind” when ultrasound is available (especially if it goes wrong) The best solution I have come up with is for each patient, after I have positioned them but before I put the probe on the patient, I use landmarks to estimate where I think the vein is and mark the spot. Then I put the probe on and see how close I was. Thus whilst I have not done a line without ultrasound for several years, I think I can still do it using landmarks if I had to.

  5. Viking One says:

    I have been using US on and of for the last 10 yrs.
    Currently I have found my balance where I divide the “patient population” into two groups.. the ones that I know might be challenging ie short/no neck, fat, subcutaneous/surgical emphysema, previous difficulties with central line placement ect… and use US straight away… then there is the other group, which is by far the LARGEST group of patiente.. I used landmark technique… If I struggle, I will go and find us US probe and use that..
    By using this method, I believe that I keep my skills for landmard use, and still dont sacrifices patient safety… and so far, there has been no PTX’s, although doing a good number of lines pr week in theatre and the occasional one prehospital or doing retreival medicine….

    By the way, I dont get the terminology – REAL time… In my mind it is difficult / impossible = NONSENSE to not have real-time…. what time would you use otherwise…..

    • Thomas D says:

      I use US for CVCs much like you do – with a little twist: I must admit I often take a sneak peek with the ultrasound probe on the low risk patients. If all I see is a big, bulging vein and nothing else out of the ordinary, I will put down the probe and happily do the procedure blindly (half-blinded?). But often I don’t have an ultrasound machine immediately available, and if I consider the patient low risk, I will go by landmarks only.

      I agree the term real-time as it’s used in the paper isn’t optimal, but for most anaesthetists, who are mainly proceduralists, real-time refers to the time we use on procedures. Everything else is not real-time 😉

  6. Matt says:

    There needs to be a study comparing ultrasound guidance in “emergent” lines. Check time from start to finish, complications, etc. I would actually hypothesize that the ultrasound guided method may perform equally well with less risk.

    Now, I think the issue is that people always mention the “what if” scenarios (ie I don’t have one, broken, can’t find it, etc). I’m sure those things will happen, but if you know your landmarks (ie which you should know if you are doing a central venous catheter) then what is the real change in the scenario? Simply teach residents landmarks – memorize them – then use them in the future if absolutely necessary.

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