#POCUS #IMPOCUS #Nephrology image of the day:
Back to basics of lung #ultrasound: A-lines and B-lines
See for brief explanation. #MedEd

2/ A-lines: hyperechoic, horizontal lines arising at regular intervals from the pleural line seen in normal aerated lung.
These are reverberation artifacts that arise when the ultrasound beam reflects off of the pleura and, instead of entering the probe, partially reflects off of

3/ the probe face back to the pleura again before getting back to the machine. This double-length pathway is interpreted and displayed as if the source of the echo lies at two times the distance between pleura and skin because, the distance

4/ at which a particular structure is displayed on the screen depends on how long the echoes returning from that structure take to reach the probe. Multiple reverberations result in multiple A-lines, at multiples of the pleural depth. #POCUS

5/ B-lines: discrete laser-like vertical hyperechoic artifacts that arise from the pleural line and extend to the bottom of the screen without fading, move synchronously with lung sliding.
B-line formation is incompletely understood but they are believed to be ring-down artifacts

6/ In case of increased lung water/edematous interlobular septae, the ultrasound beam encounters a unique arrangement of air-water interface: fluid trapped between a tetra-hedron of air bubbles. The ultrasound energy then creates vibrations within the fluid

7/ creating a continuous sound wave that is transmitted back to the transducer. This is displayed on the monitor as a streak or series of parallel bands appearing as a single vertical hyperechoic line = B-line. #POCUS

8/ Overview of lung #POCUS on RFN (2 parts)
https://www.renalfellow.org/2020/04/08/an-overview-of-lung-ultrasound-for-the-nephrologist-the-covid-19-edition-part-1/ https://www.renalfellow.org/2020/04/17/an-overview-of-lung-ultrasound-the-covid-edition-part-2/