Coarse rales · crepitations (older terms)
In one sentenceLonger, lower-pitched and louder discontinuous sounds. They occur mostly in early-to-mid inspiration and may also be heard in expiration.
Listen to the same sound in another patient. Breathing rate, chest wall, the pitch of the sound and the number of adventitious sounds vary within realistic limits.
What does it sound like?
Bubbling, with a "popping bubbles" quality. Less frequent and more irregular than fine crackles.
Where is it heard?
Regional or widespread. They follow the anatomical distribution of the disease.
What causes it?
In larger airways with secretions, fluid moves with the flow. Fluid bridges that close the airway break suddenly. The opening of larger airways also contributes. These events produce longer, lower-pitched sounds than fine crackles. Coughing moves the secretions, so the sound may change.
Quantitative criteria
- IDW ≈ 1.5 ms, 2CD ≈ 10 ms (CORSA reference values). The distributions of fine and coarse crackles overlap.
- Measurements of crackle timing and waveform show good test–retest reliability (bronchiectasis, cystic fibrosis).
Clinical meaning
Bronchiectasis, airway diseases rich in secretions, pneumonia, oedema. Crackle timing may be more informative than crackle type. In 3,684 adults aged 40 and over, bilateral early inspiratory crackles were more strongly associated with COPD than bilateral coarse crackles (adjusted OR 6.88 and 7.63 for the two observers). Even so, they do not establish the diagnosis on their own (PPV ≈ 23%). A change with coughing or airway clearance favours mobile secretions.
Sounds it can be confused with
Fine crackles are brief, high-pitched and late inspiratory. They do not change with coughing.
A rhonchus is a continuous sound. Coarse crackles are made up of separate bursts.
Note in which part of inspiration the crackles begin. Timing shows better inter-observer agreement than the fine/coarse distinction.
See the reference list for sources.