For about a year now I have been spending time “working” for the Ultrasound Leadership Academy – run by the team from the Ultrasound podcast. It is really cool to be able to chat with enthusiastic US learners all over the globe about the clinical coal-face of US in medicine. One question I get asked a lot: – what is the most useful US modality for me?
Well I reckon that lung US is now a clear winner. Why? Because it is so useful in really common, everyday scenarios. It does guide diagnosis and also therapy and can be a life-saver from time to time. A lot of the other uses of ED Bedside US are applied in less common situations and may not really effect outcomes in a lot of patients [I will get in trouble for saying that!].
So I feel that lung US is the thing I would teach to a keen MEd Student if they asked me to give them one US skill to make their early postgrad years go better. But the problem is that this is a relatively new concept – unless you are from Europe – where it has been going on for 20 + years. But for the English-speaking world it is pretty new and just making its way into clinical algorithms.
There are a few problems to overcome when learning lung US;
- The set-up on your machine is unlike any other that you have used before [mostly there are no pre-programmed modes.]
- It is all about artefacts – we are looking for things that are not really there – patterns in the smoke that represent various entities, rather tun actually visualising the “real anatomy”
- There is a steep learning curve… clinical correlation is required
- This is like many US uses – very user-dependent. It takes practice to get consistently good images.
Luckily [for me and you] I had the good fortune of bumping into Dr Kylie Baker a few weeks ago at the ASUM [Australasian Society of US in Medicine] Conference in Melbourne. Kylie is an ED doc from Ipswich in Queensland and has been contributing pearls to the Intensive Care Network on lung US in critical care. So I put her on the spot and asked her some really dumb questions about lung sonography! The result is this podcast.
I highly recommend having a listen if you are at all interested in improving your ability to treat patients with acute chest disease.
Here is a basic “How To” list that I have compiled from my discussions with Kylie. You need to know how to make your machine do chest scans – this is the quick guide for dummies.
(1) Patient: enter patient ID and data for future ref and learning. Review is crucial to learning!
(2) Probe: select curvilinear probe initially for routine 8 zone scan
(3) Position: patient supine / semi-supine. If they can sit for posterior scans – great. Depends on clinical context and your diagnostic goals.
(4) Settings: TURN OFF any automated features that may decrease artefacts – e.g.. Tissue harmonics, multi beam, sonoCT, minimise greyscale range
(5) Preset: Abdomen is OK. [NB: Lung preset on newer machines is really only optimised for pneumothorax scans - not other lung scanning.]
(6) Depth: 10 – 12 cm in a normal sized person. You may need to adjust this if your machine has a fixed focal depth
(7) Focus – aim to focus on the pleural line. (If this is fixed – then decrease depth to bring pleura close to mid screen.)
(8) Frequency: push the probe to the lowest (Penetration) frequency possible.
(9) Hand position: visualise the pleural surface and aim to keep the beam perpendicular to he pleura. [for pneumothorax - a slight angle may help] ***The absence of “A lines” suggests an incorrect setup or too large an angle on the pleura
(10) The scan: Sample each of the zones (2 anterior, 2 lateral +/- posterobasal on each side) If abnormalities are found – esp. focal changes – then this area can be further interrogated with a more thorough scan or a linear probe
Other great resources on Lung Scanning :
This from the Queen of Lung US – Dr Vicki Noble via Ultrasound Podcast – there are 2 parts to the lecture
Back to Basics on the Lung artefacts with Dr Mike Stone (the other Mike) of US Podcast – also a 2 part deal.
Some great pointers from Dr Rob Arntfield from Western Uni IN Canada at Western Sono tutorials. This video shows the positions of the probe well.
And guess what – all of these great lung US teachers are also “professors” with me at the Ultrasound Leadership Academy. Check it out if you want to take your US skills to the next level.
If you have questions, comments or your own Lung US pearls – then please share on the comments below
Big thanks to Dr Baker for her time and expertise