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Carl Scott wrote 07-26-2011 01:22:18 pm
The Fragou study seems to have a very high rate of complications, and some that should be vanishingly rare.... this would suggest that the practitioners were inexperienced, and then U/S would, of course, show a greater benefit than with a different operator group....
Previous studies have shown little benefit for U/S in subclavian CVLs, but a study in previously or potentially difficult patients may show great benefit....

Vikram Masurkar wrote 07-26-2011 02:33:23 pm
Thanks Todd

Very interesting article but it has its flaws. As Carl pointed out, the complication rate in the landmark group is high. These were operators with >6yrs experience. 4.9% incidence of pneumothorax is way above the 1% that would be expected from operators with this amount of experience (Ref Irwin Rippe's Intensive Care Medicine). Unfortunately the technique is extremely operator dependant
The other issue is whether this would work in the hands of less experienced doctors. Since I am involved in U/S guided vascular access teaching, one problem I often notice is the inability of doctors to track the tip of the needle. The consequences of this, especially with the subclavian route can be disastrous.
Personally, I'm quite comfortable using this technique for subclavian lines. I am not so sure if it will be universally accepted.
Should we completely do away with the landmark technique? Probably not. I keep my landmark technique skills up by occasionally scanning first to check anatomy and then doing the landmark technique. I know there isn't any evidence for this, but its the only way to keep your skills up. Our US machine has broken down on a few occasions. That doesn't leave us with any choice!
I think we need a balanced view on this. If a (working!) ultrasound machine is available in the unit it would be unwise not to use it at all.

Cheers,
Vikram

Todd Fraser wrote 07-26-2011 04:14:25 pm
Thanks Vikram,

You refer to the course that you are involved with. I think this highlights an important component to this - introducing new technology without concern for mandatory training and competency assessment is fraught with danger.

My concern with this is obvious - on the basis of research like this and access to an US machine, the user suddenly feels infallible. And worse, its medico-legally defensible - "Its not my fault I hit the right atrium, I was using the ultrasound..."

What is the course that you are involved with?

Vikram Masurkar wrote 07-26-2011 04:50:06 pm
The twice yearly course we run is a 1 day workshop which includes a lectures on 1. Introduction to ultrasound physics and knobology 2. Technique of U/S guided vascular access. This is followed by hands-on skill stations which include scanning on volunteers and needle guidance technique practice.
As you rightly pointed out a workshop is an intoduction to the technique. We need to move towards a credentialing process to make sure that the technique is used properly. This is want I plan to do in our unit.
I have seen a few complications which have occurred despite the use of ultrasound, clearly because of an improper understanding of the technique. Junior doctors should be aware that US guidance does not mean 0% complications unless they know what to do.

Alex McKenzie wrote 07-27-2011 11:51:26 am
That's the problem - with all this "evidence", its difficult to defend not doing it. But at the same time, there is a lack of standard in how to do it.

Is anyone aware of any credentialling guidelines on how to do it?

Oliver Arkell wrote 07-27-2011 09:06:09 pm
How do you access the course?

I don't think we can afford not to use US now. Like it or not its pretty much medicolegally indefensible not to use ultrasound, especially with big organisations like CDC recommending its use.

Vikram Masurkar wrote 07-28-2011 01:27:06 pm
Hi everyone,

Check this out -> Bedside ultrasonography detects significant femoral vessel overlap: implications for central venous cannulation.
CJEM. 2011 Jul;13(4):245-50.
Another reason to use ultrasound!

The mean (± SD) percentage of exposed vein at the inguinal ligament was 83% (± 21). This decreased significantly (p < 0.01) with increasing distance from the inguinal ligament: 65% (± 25) at 2 cm and 56% (± 30) at 4 cm. At every distance away from the inguinal ligament, there were some subjects with no vein exposed.
This study demonstrates significant overlap of the femoral vessels at sites where landmark-based femoral vein cannulation is often attempted. The results suggest that ultrasound guidance would be beneficial as femoral vein cannulation may be difficult or impossible in certain individuals owing to anatomic variations.

If anyone is interested in our workshop, contact me on vikram_masurkar@health.qld.gov.au

Cheers,
Vikram

Todd Fraser wrote 07-28-2011 05:58:17 pm
The other problem, of course, is that US isn't universally available. I do a bit of retrieval and many of the smaller hospitals I have retrieved from don't have a scanner, meaning you have no alternative but to put the line in by traditional landmark methods.

Vikram's approach of using both is fantastic. Finding the position with landmark methods and briefly confirming this with ultrasound before proceeding may facilitate skills retention (and infact may enhance them by directly visualising the anatomy).

Alex McKenzie wrote 07-30-2011 03:28:19 pm
Interesting paper just out showing the rate of pneumothorax when lines are inserted under ultrasound guidance is extremely low. The authors suggested you don't even need to xray.

http://bit.ly/ovIwyg

Vikram Masurkar wrote 08-01-2011 11:12:16 am
Good point Alex.
If you put in an U/S guided line and want to rule out a pneumothorax, U/S is probably the best modality. Its quick and much more sensitive for a small anterior pneumothorax compared to a CXR.
Cheers,
Vikram

Oliver Arkell wrote 08-01-2011 12:18:20 pm
What about line position though? Its all very well to rule out pneumothorax (and I wonder if some of them take more than the 10 minutes it takes to get an xray to develop anyway), but don't you have to check the position of the tip?

Robyn Cooke wrote 08-01-2011 01:18:28 pm
USS and placement CVC.
Great comments and I agree with Vikram - I use both landmarks and USS. I think its important to be familiar with both for two reasons - 1) avoiding complications - its not just the pneumothorax that you wish to avoid, but needless stabbing in the wrong spot, arterial versus venous (obviously IJ position) also one can check that the guidewire is going in the right direction. USS allows one to do this quickly and easily. Also, if there is a question mark over the persons coags (as is often the case in the sepsis patient) then by only having one or two puncture marks - it minimises bleeding and haematoma risks.
2) important to use landmarks - because of those situations when the USS is unavailable (good point in small rural hospitals without the equipment).
So here's a tip, this is how I use USS - when setting up, I go by landmarks, then check with USS to see if I agree with myself. If not a major bleeding risk, I'll then place the needle without the USS. If worried about a potential complication I'll use the direct vision under USS.
As for the need for CXR - well, I thought it was not just checking for pneumothorax (important for subclavian's) but also to check the actual tip is in the correct position - so I think CXR are here to stay. Does anyone else have comments about this?

Todd Fraser wrote 08-02-2011 09:53:55 am
Just on the issue of tip placement, I have wondered if there is a consensus on the best place? The literature seems divided on the issue - some say the tip should be above the pericardial reflection at the level of the carina, others suggest, particularly for left sided neck lines that the angle the tip makes with the wall is a bigger issue and elect to push it in a bit further.

What do others do?

Robyn Cooke wrote 08-05-2011 01:39:56 am
Tip placement. I have been taught that what is important is to avoid placing the tip where it can cause an erosion into a vessel wall or heart wall. Hence, not buried in the heart and if left sided (as you pointed out) push further so not pushing against the wall of the vessel.