SonoTip&Trick: “I can’t tell if there is normal lung sliding.” Here’s a quick tip….

All of us have had that case where we had a thoracic trauma victim or an acutely short of breath patient who we want to evaluate for pneumothorax. We use the ultrasound machine since it’s quick and more accurate than chest XRay. We place the linear probe on the anterior chest wall, indicator toward the head at the 2nd intercostal space and midclavicular line, and see this:

We think: I dont see lung sliding very well, maybe I should travel to another rib space, but we continue to see the same thing. We know that for confirmation of the above diagnostic evaluation, we should use M Mode but we see that it doesnt really help much – no true sandy beach or seashore sign.

Here’s a tip: DECREASE THE GAIN! (darken the image) – I know, crazy, right?!

I know that when we all first learned ultrasound and we couldn’t see what we wanted to see on the screen, we immediately increased the gain to make the image look more bright – that’s the wrong thing to do (unless, of course, you just decreased the gain for a prior image due to posterior acoustic enhancement and now need to re-calibrate (if you will) and increase the gain back to its original state. This is a testament to how that will fail you. When you decrease the gain in evaluating for pneumothorax, you will allow the sliding lung to be more apparent (as some describe like ants crawling on the screen) and those comet tail artifacts to be easily visible. Look at what happens when you decrease the gain:

This is mainly helpful when you have someone who is not breathing very fast, the slow slide will be difficult to see….but see below how the decreased gain can help with that as well…


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