College Answer
- Loss of comet tails and “marching ants” appearance
- Ribs and pleura move together
- “Lung point” – motionless horizontal lines are replaced by normal lung appearance moving from non-dependent to dependent region and also seen with inspiration and the probe held stationary.
- Loss of “waves on the beach” appearance in M-mode
Discussion
This is one of those things which is better explained with pictures.
In dry boring words, there is a list of features which one can easily memorise:
- Absence of "Seashore sign" on M-mode
- Absence of "B-lines" or "comet-tails" moving in synchrony with the pleura
- Absence of sliding lung
- Lung point sign - the point where the pneumothorax transitions into normal lung