Crackles (Rales)

Crackles are discontinuous popping sounds that are heard primarily during inspiration. Contrary to popular opinion, they are not from the popping open of alveoli. In the larger airways they are thought to be caused by secretions bubbling in the airways, while in smaller airways they are thought to be caused by the popping open of the airways during inspiration. The sounds are varied, and are said to resemble the sound you hear when rubbing hair close to your ears, the crunching of leaves, or like the tearing of Velcro. Crackles may be differentiated by their quality (fine versus coarse) or by where they fall in inspiration.

Pulmonology Tutorial

Patient 6

This is a young man with cystic fibrosis complicated by bronchiectasis (more severe in the left lung). Notice that the rales are coarse and mid-inspiratory.

Mid-Inspiratory Crackles

Annotated

Mid-Inspiratory Crackles

Annotated