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
I am a GP working in Broome, NW of Western Australia. I work as a hospital DMO (District Med Officer) doing Emergency, Anaesthestics, some Obstetrics and a lot of miscellaneous primary care. Also on the web as @broomedocs | + Casey Parker | Contact