Absent or Decreased Breath Sounds
There are a number of common uses for absent or decreased breath sounds, including:
- Asthma: decreased breath sounds
- Atelectasis (Collapse): If the bronchial obstruction persists, breath sounds are absent unless the atelectasis occurs in the upper lobes when adjacent tracheal sounds may be audible.
- Fibrosis: decreased breath sounds, unless fibrosis occurs in upper lobes when adjacent tracheal sounds may be audible
- Emphysema: decreased breath sounds
- Pleural Effusion: decreased or absent breath sounds. If the effusion is large, bronchial sounds may be heard at the upper level of fluid.
- Pneumothorax: decreased or absent breath sounds
- ARDS: decreased breath sounds in late stages
Vesicular breath sounds may also be softer if the patient is
- obese, or
- very muscular
Listen to the audio of a diminished vesicular breath sound:
Harsh Vesicular Breath Sounds
Vesicular breath sounds may be harsher and slightly longer if there is
- rapid deep ventilation (eg post-exercise) or
- in persons with thinner chest walls.
Listen to the audio of harsh vesicular breath sound:
Bronchovesicular Breath Sounds
These are breath sounds of intermediate intensity and pitch. The inspiratory and expiratory sounds are equal in length. They are best heard -
- in the 1st and 2nd intercostal space (anterior chest) and
- between the sapulae (posterior chest) - i.e., over the mainstem bronchi.
Listen to the audio of bronchovesicular breath sound:
Bronchial Breath Sounds
Bronchial breath sounds are usually loud, high-pitched and sound close to the stethoscope. The following are the features of bronchial breath sounds:
- character is HOLLOW.
- there is a gap between the inspiratory and expiratory phases of respiration
- the expiratory sounds are equal in length to inspiratory sounds.
If these sounds are heard anywhere other than over the manubrium, they indicate an abnormality (these sounds are also heard over the trachea, but trachea is NOT a standard area for auscultation).
These are the common causes of bronchial breathing:
- Upper level of pleural effusion
- Upper lobe fibrosis
- Upper lobe collapse
- bronchopleural fistula
The ideal method to recognize bronchial breathing while auscultating is to look for the hollow character of the sound. Then confirm that it is indeed bronchial breathing by looking for the gap between inspiration and expiration and the equality of these two phases of respiration.
Do not try to identify the bronchial sound by looking for the gap or equality of phases! You will spend a lot of time and also miss the bronchial often. Look for the hollow character. You will rarely go wrong.
Listen to the audio of bronchial breath sound:
The mp3 audio clips used in this article can be downloaded from our downloads section. Please remember that these are for teaching-learning purposes only.