Wet rales are sounds produced by the rupture of blisters formed by gas passing through secretions such as exudate, sputum, blood, mucus and pus in the respiratory tract during inspiration, so they are also called blister sounds. Or it is thought to be the bursting sound produced by the wall of the small bronchus trapped and closed due to adhesion of secretions, which suddenly opens and re-inflates when inspiration is applied. Wet rales are one of the most important signs during auscultation of the lungs. The mechanism of formation is due to gas passing through the airways, and if there are secretions (such as sputum, exudate, blood, mucus, pus, etc.) in the airways, blisters are formed, which are produced when the blisters rupture. Features Wet rales are additional sounds to breath sounds, intermittent and transient, often appearing more than once in succession, and are obvious during inspiration or at the end of inspiration; sometimes they also appear in early expiration, the location is more constant, and the nature is not easy to change. Classification 1, coarse wet rales: occurring in the trachea, main bronchus or cavity site, mostly in the early inspiration. 2, medium wet rales: occurring in the medium bronchus, mostly appearing in the late inspiration. 3.Fine wet rales: occurring in small bronchi, mostly appearing in the late inspiration. 4.Twisted sounds: very fine and uniform wet rales, mostly heard at the end of inspiration. Wet rales are the manifestation of lung and bronchial lesions. The scattered distribution of wet rales is common in bronchitis, bronchopneumonia, hematogenous tuberculosis, pulmonary edema; distribution at the base of both lungs is common in pulmonary stasis, pulmonary edema, bronchopneumonia; one-sided or limited distribution is common in pneumonia, tuberculosis, bronchiectasis, lung abscess, lung cancer and lung hemorrhage.