|Author: A. Chandrasekhar, MD|
There are two normal breath sounds. Bronchial and vesicular. Breath sounds heard over the tracheobronchial tree are called bronchial breathing and breath sounds heard over the lung tissue are called vesicular breathing. The only place where tracheobronchial trees are close to chest wall without surrounding lung tissue are trachea, right sternoclavicular joints and posterior right interscapular space. These are the sites where bronchial breathing can be normally heard. In all other places there is lung tissue and vesicular breathing is heard.
The bronchial breath sounds over the trachea has a higher pitch, louder, inspiration and expiration are equal and there is a pause between inspiration and expiration.
The vesicular breathing is heard over the thorax, lower pitched and softer than bronchial breathing. Expiration is shorter and there is no pause between inspiration and expiration. The intensity of breath sound is higher in bases in erect position and dependent lung in decubitus position.
The breath sounds are symmetrical and louder in intensity in bases compared to apices in erect position. No adventitious sounds are heard.
Breath Sounds by Dr David W.Cugell NW University Chicago