Crackles

Crackles are the clicking, rattling, or crackling noises that may be made by one or both lungs of a human or animal with a respiratory disease during inhalation, and occasionally during exhalation. They are usually heard only with a stethoscope ("on auscultation"). Pulmonary crackles are abnormal breath sounds that were formerly referred to as rales. Bilateral crackles refers to the presence of crackles in both lungs. Basal crackles are crackles apparently originating in or near the base of the lung. Bibasal crackles, also called bilateral basal crackles, are crackles heard at the bases of both the left and right lungs. Crackles are caused by the "popping open" of small airways and alveoli collapsed by fluid, exudate, or lack of aeration during expiration. Crackles can be heard in people or animals who have pneumonia, atelectasis, pulmonary fibrosis, acute bronchitis, bronchiectasis, acute respiratory distress syndrome (ARDS), interstitial lung disease or post thoracotomy or metastasis ablation. Pulmonary edema secondary to left-sided congestive heart failure and high altitude pulmonary edema can also cause crackles.