Breathing produces some type of sound. The sound can be heard well with the help of stethoscope during auscultation of chest. This sound that you hear is called breath sound. Breath sound is categorized into two types; normal and abnormal. Breath sound is especially important for clinical assessment of lung, although there are many newer technology evolved over years to detect lung pathology.
Bronchial breath sounds are sounds that are heard during inspiration and expiration. Breath sound originates from the velocity and turbulence with which the air passes and causes vibration in the air passage or the bronchi. The vibration is then transmitted to the lung and chest wall from where it can be easily heard with the help of stethoscope.
Bronchial breath sound is heard during inspiration and expiratory phase of breathing. The sound is louder while breathing in. It can be heard properly when you keep your stethoscope over trachea and larynx.
Where Can You Hear Bronchial Breath Sounds?
Normally bronchial breath sound cannot be heard over your thorax when you are resting.
The sound heard over the hilar region is termed as bronchovesicualr sound. If bronchial sound is heard over the thorax wall it is suggestive of some lung pathology such as pneumonia and certain other pulmonary disease. When the lung is consolidated as in case of pneumonia, the sound transmission from major bronchi is heard with more intensity on chest wall, which in normal circumstances in not heard.
Another type of normal sound called vesicular breath sound is heard on the periphery of lungs, especially during the inspiration. In case if the sound intensity is increased it may suggest something pathogenic of the lung tissue.
What Causes Abnormal Breath Sounds?
Normally when the air passes through trachea and primary bronchi, breath sound is heard due to its intensity and vibration generated in the air passage wall. But you can also hear abnormal breath sounds in the form of wheezing, ronchi, and rales. Certain pathological conditions of lung produce these typical sound while auscultation of chest wall. These causes include:
- Chronic obstructive pulmonary disease, asthma, emphysema, etc. All these diseases produce abnormal breath sound.
- Tuberculosis, pleural effusion, pneumonia all produces abnormal breath sound. In fact a clinician often diagnoses pleural effusion when he hears typical breath sound during auscultation.
- Abnormal breath sound is also an indication of congestive heart failure. The accumulated fluid in the lung tissue precipitates abnormal breath sound.
Symptoms Of Bronchial Breath Sounds
Abnormal breath sounds can be of different types. They indicate different diseases and pulmonary problems.
- Ronchi or crackle: An obstruction in the lower respiratory tract can produce a typical sound called ronchi. It is an explosive sound which has its origin in the air passage. The obstruction can be caused by accumulation of mucus in the air passage, inflammation of the airways or edema in the lung tissue. Crackles are more clearly heard during inspiration.
- Wheezing: Wheezing sound from the lungs is heard when there is swelling of the primary bronchi. It usually occurs in asthmatic patients. The sound is similar to when air is forcefully passed through a thin metal tube. High or low pitch will depend on the extent the airway is narrowed due to edema.