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August 11, 2012

Questions for Haney on SCUS

Haney Mallemat (EM/IM/CCM@UMEM) just put together a great screencast on subclavian ultrasound for CVC placement. Definitely worth the ~8 min watch.

I had a few questions for Haney and some opinions of my own so I figured I'd put it here instead of in discrete, 140-character (minus @tags) snippets.

To be clear: I think this is a great talk about a simple way to improve a procedure; these are just little bits around the edges.

1) Doppler

You describe how to use doppler to identify the vein vs artery. I think that's a great idea (and I do it occasionally, mostly to ID the IVC when assessing fluid responsiveness) but it can be a little technically difficult, particularly since some machines (including one of my current ones) can't do it.

I use color doppler rather liberally to ID vessels -- arteries give you big, colorful, pulsatile bursts; veins smolder.

2) PTX in SC

You mention the risk of pneumothorax with SC, and I love the picture of the proximity of the pleura to the vein we generally stab at blindly. However, is the risk overblown? We know how to recognize & treat pneumothoraces, and Scott Weingart contends that with proper technique (needle stays parallel to floor the entire time) the risk is minimized.

3) Ultrasound Saves Time

People who are reluctant to use US often cite the extra time needed to use US when placing a line (you allude to this, too, despite your clear preference for US!).

My feeling* is that US saves time for central lines. Maybe not for the simple, 1&done easily placed lines.

But a lot of them aren't that simple. There's probably some bimodal distribution of lines: some go in right away and another big chunk involve rooting around in soft tissue and kinking the heck out of wires for 20-30 minutes. Facility with US really helps minimize the second group, increase the 1&dones, really adds only a minute to wheel over the machine and place a probe cover, and is not difficult at all. (And you can do all of this alone.) And it shows you exactly where to go.

I really think that once you get mediocre at US-placed lines, then it saves time on every line.

4) Femoral Lines

I don't want to rehash Matt's great femoral line argument with Minh, and I recently got in a twitter fight with @talesfromtheer et al on some of this, but some bullets:

  • femoral lines are terrible in codes
    • the vein collapses during hypotension, making it hard to find and harder to cannulate
    • it can appear arterial (by palpation or US) as chest compressions push both ways
    • landmarks & anatomy are unreliable
I'm not saying to never use place a femoral line, but if you do I really think you should absolutely use ultrasound. 

While a subclavian seems inconvenient during a code, if you need a central line it's probably much better, particularly because there are ligamentous structrues tethering it open, even when BP is nil. And the landmarks are actually reliable (as opposed to the IJ & fem). But go ahead and use an US!

Or better yet, place an IO. (drill, baby, drill)

(My main theory on the popularity of femoral lines during codes is that notion that the intern can mess around with the line while the important people do important things closer to the head of the bed.)

5) No Neck?

This is all in good fun, but it looks like the patient you used as your example in the video actually has a left IJ and another line on the right (possibly an HD line?) -- screenshot above.

Again, great video and I'm looking forward to trying it out.

*I don't have evidence or data. I didn't even look it up.

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