Bronchial breathing: What is it, its mechanism, and what causes

Bronchial breath sounds are loud, harsh and high-pitched breath sounds.

These sounds are normal if heard over the tracheobronchial tree, but are considered abnormal if heard over lung tissue upon auscultation.

The sound quality is tubular, both inspiratory and expiratory are equal or the expiratory phase is longer. There is a definite gap between both phases of respiration.

Mechanism of Bronchial Breathing

Bronchial breath sounds (sounds of air moving in bronchi) are not normally heard over the lung fields because the chest wall and alveoli muffle higher-frequency sounds.

In the presence of consolidation, however, the alveolar ‘filter’ is replaced by a medium that transmits high-frequency sounds, allowing bronchial breath sounds to be heard.

Collapsed alveoli also act as an effective transmitter of sound and higher frequencies.

Condition/s associated with Bronchial Breath sounds

• Normal over the trachea

• Pneumonia

• Pleural effusion – heard above the level of effusion

• Atelectasis with a patent bronchus. Collapse with blocked bronchus will lead to absent or muffled sounds.

• Adjacent to large pericardial effusion

• Tension pneumothorax

Extra Tips: If you hear bronchial breath sounds due to consolidation, you may be able to elicit additional signs by doing some manoeuvres. These signs are:

Increased Tactile Fremitus

Bronchophony (Vocal resonance)

Aegophony – if you ask the patient to say ‘BEE’, you will hear it as ‘BAY’ on auscultation

Whispering pectoriloquy – Normally, whispered sounds by the patient would not be heard by the clinician auscultating lungs. Whispering pectoriloquy is an increased loudness of whispering notes during auscultation on the affected area of the lung.