January 23, 2013
Shear wave elastography

Here’s a nice image about shear wave elastography as an adjunct to ultrasound for neural imaging. Looks quite promising. I wonder what the imaging looks like with a needle in their too.

Sorry I haven’t posted in a good while. Been a bit snowed under.

August 17, 2012
A new home for the LA toxicity app

The LA toxicity app has been updated to allow single drug calculation as well as combination drugs, and has a new home on our website.
The site contains instructions on installation along with links.
Anyone interested in proper app development for iOS please contact me.

August 2, 2012
How much simulation for UGRA is enough?

I’m running a follow up survey about our UGRA course (next one at UCLH in December, follow the link on this blog, plug, plug).

I had an interesting response from a consultant anaesthetist, who felt that we were advocating too much simulation prior to actual patient performance of UGRA, especially is one had transferable skills from ultrasound guided vascular access.

Now, I for one think there is a vast difference between being able to hit a structure 1.5cm across using an out of plain technique, versus bringing a needle in plane to avoid a target of less than 2mm in some instances, however I agree there will be some who achieve this in a shorter time frame than others.

The secret to success is to ensure that you have a good mentor who can watch your progress from needling low fi phantoms, through to practicing on high fidelity phantoms then supervised patients, before finally flying solo with reducing supervision. This goes for consultants as much as trainees, and this is where UGRA can lead to problems.

Ultrasound guided procedures are not a natural progression for most people, and you can cause serious harm without adequate training and supervision. You are probably better off with a nerve stimulator if you can’t put the time in to adequately train yourself up prior to patient contact (but this learning curve will vary greatly from person to person), and you won’t be putting your patients at risk to the same degree. If this is not achievable within your own allotted time frame to learn, then don’t bother.

Equally I believe that the skill is worth learning, and has great benefit for patients, and can be achieved by most people within a reasonable time frame.

July 22, 2012
Journal Club

Heres a stimulating article on where the needle tip should be in UGRA, 

http://journals.lww.com/co-anesthesiology/Abstract/publishahead/Where_should_the_tip_of_the_needle_be_located_in.99605.aspx

As ever, email me for a copy if you can’t access through institutional access and I’m happy to provide it to you as a academic use courtesy.

My opinion is that, despite nicely produced work by Bigeleisen et al, the numbers are not enough to convince me that deliberate subepineural injection is a good idea, when we have a better idea of when we are doing it (although as the article nicely summarises, we don’t know for sure).

I’m fairly convinced that the interscalene block is one of the “fascial plane” approaches they are talking about, but the supraclavicular most definitely isn’t. 

July 17, 2012
Look at this beautiful image of the brachial plexus courtesy of Johns Hopkins. 
It’s a MIP of a brachial plexus MR neurography scan. I’ve never seen the plexus represented like this before, and very easy to see the complexity of its many divisions.

Look at this beautiful image of the brachial plexus courtesy of Johns Hopkins.
It’s a MIP of a brachial plexus MR neurography scan. I’ve never seen the plexus represented like this before, and very easy to see the complexity of its many divisions.

July 13, 2012
Congatulations

Congratulations to Dr Adrien Desjardins PhD at UCH who has just secured significant funding from the European Research Council for investigating novel new ways of enhancing neural and vascular contrast under ultrasound. I’m looking forward to him hopefully providing the missing link in regional anaesthesia to tell us the exact boundaries of the nerve, and maybe even more?

July 6, 2012
Spatial compounding

Try switching off the spatial compounding on your machine to see what a difference it makes (on the GE machines, just press the soft key marked “crossbeam” on the main screen). Once you try it, you’ll realise why this is the only essential image processing you need on an UGRA machine.

July 5, 2012
Needle enhancement software

Further to my previous post on beam steering for needle visualisation. Remember that this technology does not improve a skewed needle tip, only improves the visualisation of a deep needle that is already in plane.

July 1, 2012
What’s next for needle imaging (hardware)

The main drive currently is for magnetic tracking systems, which I’ve written about before.
These were invented some 10 years ago, but it’s only the resurgence in interest in RA that’s led to wider implantation commercially.
There are systems available from Ultrasonix and also from GE. Essentially, the needle has magnetic sensors embedded into it, and these are picked up by a transducer on the ultrasound machine. This translates the 3D coordinates of the needle onto a visual representation of the needle on screen. Accuracy is around 2-3mm from what I can gather, which is perfectly reasonable for vascular access, although I’m not sure whether this is enough for UGRA personally.
The nice thing they do, is plot a trajectory for you, even before you’ve penetrated the skin, and even out of plane. This “pre-planning” could reduce number of needle passes significantly, though they need to prove it.

July 1, 2012
What do those “new” ultrasound imaging features mean?

Ultrasound manufacturers, like every other commercial company, like to add new features to their machines to trounce the competition, some are better than others. So what do the main imaging upgrades mean?

Spatial compounding goes by a number of names (eg Crossbeam or SonoMB). This is an essential feature in a modern machine, it basically means that over a series of frames the transducer fires sound over a wide range of angles, rather than just perpendicular to the head. The multiple images are merged and speckle and noise are vastly reduced.

Beam steering (SonoMBe), this one seems to confuse people (I heard one regional enthusiast telling people how his new “biplanar” S Nerve was so good at showing the needle, I had to laugh). When you switch this mode on, you choose a direction and an angle to “steer” the beam so it hits the needle at a decreased angle, this then creates one frame in every few where the beam is deliberately fired in the specified direction, this image is compounded with the others to produce an improved image of the needle with the standard view of the anatomy. You can create a similar effect by “heeling” and “toeing” the transducer head.

Their are many other “features” around, but these are the main 2 to know about.

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