Learn basic ultrasound skills first. Start with the lung, the gallbladder or with free abdominal fluid. Practice on the easy stuff. The science is constantly evolving. New studies demonstrating the value of bedside ultrasound and demonstrating its clinical value get published every month. Don’t wait until a headline grabs your attention and makes you think “I must start doing this” before you start learning. With basic ultrasound skills already learnt, picking up new ones is a cinch.
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Don’t become discouraged
Learning to perform ultrasound takes a long time and a lot of practice. It’s also something which is not yet routinely practiced on the wards or in clinic. This means getting access to perform scans and then feedback on your scanning is difficult. This also means most people either never start the learning journey or drop out of learning early on. But if you are willing to persist, if you can delay the gratification that comes with learning this skill, for as long as it takes, the skill is yours to own.
If you learn to do the difficult stuff which most people can’t do, then very soon, people will start asking you to do it regularly. This makes you one step closer to being indispensable. Being indispensable gives you choices, job offers, promotions and job security.
So persevere. Put in the time. In this world “discretionary effort is King”. Sometimes entire careers are built during lunchtimes and after hours.
Select the right probe
When you’re starting out with bedside ultrasound, it’s tempting to save yourself a few seconds and use the probe that’s set as the default probe for whatever you want to scan. This is a rookie error. The reason there are different probes is that any single probe design and its corresponding frequency range represents a series of trade-offs. The biggest trade-off is between resolution and depth of view. The other is between scope (the size and shape of the sound beam) and resolution. For more depth, for example to see the back of the liver, you need a lower-frequency probe but this limits the image resolution or detail that is seen. High-frequency probes are great for detail work, for example with tendons or vessels, but have limited depth of penetration and are therefore limited to superficial structures.
With scope, the wider or more fan-shaped the beam, the lower the resolution. The higher resolution seen with linear beam arrays comes with a smaller lateral field of view or scope.
Therefore when scanning abdomens, use the low-frequency, curved probe (good depth, wide scope, lower detail). When scanning superficial structures such as vessels or for foreign bodies, use the high-frequency, linear probe (shallow depth, high detail, narrow scope). When scanning the heart use the small-footprint, wide-scope probe with the lower frequency. This allows you to get between the ribs (small footprint) and see all the cardiac chambers (greater depth) but does compromise on the detail which is an acceptable tradeoff with cardiac sonography.
Practice needle procedures
Practice your needle procedures on a home-made phantom. You can do it over and over again until you are really good at them and without hurting anyone. This sounds crazy and so very few people do it. Hence, very few get really good at needle guided procedures. This is exactly why you should do this. For a cool video on making a home-made ultrasound phantom for this purpose check out this link from Clarius.
On getting started in bedside ultrasound
Browsing videos on US technique is one thing but there really is no substitute for getting good quality formal teaching and hands-on tuition early on. This provides a framework of basic technique on which to build and improve. There are many courses out there and probably many near you. In British Columbia we have the EDE POCUS course and the HOUSE course out of UBC.
Great video on US physics, artefacts and “knobology”
When you’re starting out, videos can be a great learning resource. This series by Liz Turner is a great starting point. Find the first in the series here.
Optimize your image constantly – Focus
The resolution of the image generated by the ultrasound beam is not the same across all depths. The sound waves emitted from the crystal array in the probe can be focussed electronically at a level of your choosing, which you should adjust to the level of the organ of interest. This maximizes the resolution of the image at that depth. You should alter the focus level continuously during scanning as your target organ changes in depth.
When using ultrasound to guide needles in patients (for example when inserting a central line), set your focus at the level of your needle and not at the level of the target vessel. This will help you see the position of your needle more clearly.
Optimize your image constantly – Gain
As you scan, structures of interest may dive deep in the body and will appear darker. You should increase the 2D gain control to compensate and keep your image bright enough to see clearly. When the structure becomes more superficial, you may need to decrease the gain to avoid a “white-out” of the structures of interest. Try and maintain your image in the middle of the grey scale to help different structures stand out from one another. This is called “maintaining image contrast”.
Some newer machines have an “auto-optimize” button which automatically adjusts the gain and maintains image contrast. You should push this button regularly during scanning and always after you change the depth of view.
Optimize your image constantly – Depth of view
To get the best image quality, keep adjusting the depth of view as you scan.
As you move the probe over the patient, the organ or structure of interest will be constantly varying in depth on the screen and you want to keep this structure filling as much of the screen as possible to help you see the detail. Setting the depth too large results in shrinking the target structure to a small strip at the top of the screen while the lower screen displays useless information. Try getting into the habit of maximizing your screen resolution by filling your screen with the target.
Cool video on basic lung ultrasound technique
Interested in learning lung ultrasound? Check out this cool video with Shane Arishenkoff from Vancouver General Hospital on basic technique here.