“Sign of the Bubble” positive
At hour 11: bubbles are observed in the lateral segmental of the middle lobe (RB4).
No bubbles in the medial (RB5), at hour 7 of the photograph: they report the distal obstruction of this bronchus.
It indicates that in segment RB5 the bronchoscopist must introduce the biopsy clamp to reach the tumor that obstructs it.
The bubble sign was described by Dr. Ricardo Isidoro in 2005, and published much later. (Rev. amer.respiratory med vol.12 no.4 CABA oct./Dec. 2012).