Physical Assessment: Breath Sounds

 

Evaluating Lung Air Entry and Airway Obstruction

To evaluate air entry into the lungs and detect airway obstructions, follow these steps:

Patient Positioning: Have the patient breathe normally with their mouth open.

Auscultation:

Auscultate the lungs, ensuring you cover the apices, middle, and lower lung fields posteriorly, laterally, and anteriorly.

Alternate and compare both sides.

Technique:

Use the diaphragm of the stethoscope.

Listen to at least one complete respiratory cycle at each site.

Begin by listening during quiet respiration; if breath sounds are inaudible, ask the patient to take deep breaths.

Observations:

Describe the breath sounds first, followed by any adventitious sounds.

Note the intensity of breath sounds and compare them with the opposite side.

Assess the duration of inspiration and expiration, noting the pause between them and the pitch quality of the sounds.

Comparisons:

Compare the intensity of breath sounds between the upper and lower chest while the patient is upright.

In the decubitus position, compare the intensity of breath sounds from the dependent lung to the upper lung.

Adventitious Sounds:

Record the presence or absence of any adventitious sounds.

Normal Findings

There are two types of normal breath sounds: bronchial and vesicular. Bronchial breath sounds are heard over the tracheobronchial tree, while vesicular breath sounds are heard over the lung tissue. Bronchial breath sounds can typically be heard in areas where the tracheobronchial tree is close to the chest wall without lung tissue intervening, such as the trachea, right sternoclavicular joints, and posterior right interscapular space. In all other areas, vesicular breathing is heard due to the presence of lung tissue. 

Tracheobronchial tree

Bronchial breath sounds over the trachea are characterized by a higher pitch, louder sound, equal duration of inspiration and expiration, and a pause between them.

Vesicular breath sounds are heard over the thorax and are lower pitched and softer than bronchial breath sounds. In vesicular breathing, expiration is shorter, and there is no pause between inspiration and expiration. The intensity of these breath sounds is greater at the lung bases in an erect position and in the dependent lung in a decubitus position.

Overall, breath sounds are symmetrical and louder at the bases compared to the apices in an upright position, and no adventitious sounds are present.

Abnormal Findings

Understanding Breath Sound Intensity and Abnormalities

The intensity of breath sounds is generally a reliable indicator of lung ventilation. Increased intensity indicates better ventilation, while decreased intensity suggests reduced ventilation. For instance, breath sounds are significantly diminished in cases of emphysema.

Symmetry in Breath Sounds

Asymmetry in breath sound intensity is abnormal, with the side exhibiting decreased intensity indicating potential issues. Various pleural or pulmonary diseases can lead to reduced breath sound intensity.

Abnormal Bronchial Breathing

Bronchial breathing heard outside the trachea, right clavicle, or right interscapular space is considered abnormal. This abnormal bronchial breathing can indicate several conditions, including:

Consolidation 

Cavitation

Complete alveolar atelectasis with patent airways

Mass interposed between the chest wall and large airways

Tension pneumothorax

Massive pleural effusion with complete lung atelectasis

In these conditions, alveolar ventilation is absent, and the sound heard originates from the bronchi and is transmitted to the chest wall.

Differentiating Conditions Based on Bronchial Breathing Quality

Experienced providers can distinguish between consolidation and cavitation by the quality of bronchial breathing. 

In consolidation, the bronchial breath sounds are low-pitched and sticky, termed tubular bronchial breathing. 

In cavitary disease, the breath sounds are high-pitched and hollow, known as cavernous breathing, similar to the sound produced by blowing over an empty bottle.

 In tension pneumothorax, bronchial breath sounds have a metallic quality, referred to as amphoric breathing.

Adventitious Breath Sounds

Wheeze 

Stridor 

Crackles 

Pleural Rub 

Source: Sarkar, M., Madabhavi, I., Niranjan, N., & Dogra, M. (2015). Auscultation of the respiratory system. Annals of thoracic medicine, 10(3), 158–168. https://doi.org/10.4103/1817-1737.160831