Letter to the Editor
https://doi.org/10.22514/SV141.042018.17
Unrecognized B line mimicked pneumothorax on M mode ultrasound
ALAN ŠUSTIĆ
; Department of Anesthesiology and ICU University Hospital Rijeka T. Strizica 3, Rijeka, Croatia
MARKO ŠUSTIĆ
Abstract
One of the most signifcant fndings on
lung ultrasound (LUS) are comet tail artifacts,
also called B-lines or “lung rockets”.
Te causes of such phenomena are fuidthickened
interlobular septa due to increased
extravascular lung water or clinical
pulmonary edema. Te B-lines are defned
as discrete, echogenic, vertical, laser-like
signals which arise from the pleural line
and extend to the bottom of the screen. (1)
However, although originally described
as an easily detectable sign, recent reports
indicate that other artifacts, such as Z or
E lines, may be mistakenly interpreted as
B lines (and vice versa). Z lines are short,
broad, vertical comet tail artifacts arising
from the pleural line, but not reaching the
distal edge of the screen. Tese can be seen
in normal lungs, as well as with pneumothorax.
E lines are vertical lines, which
do not arise from the pleural line, as they
originate from subcutaneous collections of
gas (subcutaneous emphysema). Tey are
not synchronous with respiratory movements,
but they do erase A lines, and may
therefore be mistaken for true B lines. (2)
Visualization of B lines is considered to
rule out pneumothorax (PNX) with a
negative predictive value of 100%. On the
other hand, visualization of a stratosphere
sign (bar code - BC) and a “lung point
sign” (the junction between PNX and an
infating lung) on M mode are established
as pathognomonic LUS fndings for PNX.
Recently, these two fndings were described
in a patient with chronic obstructive pulmonary
disease and without PNX. Te authors
concluded that these were visualized
due to the presence of bullous emphysema,
where trapped air in large pulmonary bulla
mimicked PNX. (3)
We present the images and a video clip with
presentation of BC on M mode, caused by
an (unrecognized) B line, mistakenly diagnosed
as PNX. In this case, BC was caused
by overlapping the unrecognized B line
with the cursor (line) in M mode during
respiratory movements in a mechanically
ventilated patient.
When the B line is not on the M mode cursor,
the display shows a normal M mode
ultrasound lung fnding, termed the”sea
shore” sign (fgure 1). When the B line
crosses the M mode cursor, BC is displayed
(fgure 2), and alterations of the “sea shore
sign” and BC sign can easily be mistaken
for a "lung point sign" (video clip).
Tese images point out the importance of
clear identifcation and distinction of B
lines from (in some cases) similar Z and
E lines. Both 2-D and M-modes of LUS
should be used and interpreted for accurate
diagnostic value.
Keywords
lung ultrasound; B-line; pneumothorax
Hrčak ID:
200444
URI
Publication date:
1.6.2018.
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