What Is Breath Sound Assessment?

Breath sound assessment is a standardized way doctors listen to the sound your lungs make. This helps them diagnose various lung problems.

Clinical evaluation of breath sounds is the first and most common method of assessing lung health. The stethoscope placed on the back and chest lets the physician listen to the breath sounds. This process is called auscultation. 

Assessment of breath sounds is a routine part of a clinical examination. If a pathology of the lung is suspected, assessing the breath sounds helps identify probable causes. The type and location of certain breath sounds can help make a diagnosis.

There are two types, normal and abnormal (adventitious) breath sounds:

Normal breath sounds are divided into two subcategories:

• Vesicular breath sounds: Sounds heard during auscultation of the chest of a healthy person. They can be heard all over the chest and the back.
• Tracheal sounds: Sounds heard over the sternum. They are louder and higher pitched than vesicular sounds are. 

The type and location of the abnormal breath sounds can help make a diagnosis. In the presence of abnormal breath sounds, the doctor will advise a management plan for further investigations and treatment. The types of abnormal breath sounds include the following: 

Wheezing

This is a high-pitched whistling sound that occurs breathing in or out. It’s usually a sign that there is narrowing of the airways, preventing air from flowing through freely.

The most common causes of wheezing are asthma and a group of lung diseases called chronic obstructive pulmonary disease (COPD). Other conditions that can cause wheezing include:

• Allergies
• Epiglottitis (when the “lid” of cartilage that covers the trachea swells and obstructs air entry to the lungs)
• Vocal cord problems
• A foreign body stuck in stuck in throat or trachea (windpipe)
• Infections
• Smoking
• Side effect of some medications  
• Laryngeal or tracheal tumors
• Tracheal stenosis
• Tracheomalacia
• Foreign body aspiration
• Occupational exposure to certain chemicals and irritants
• Cystic fibrosis
• Bronchiectasis
• Hypersensitivity pneumonitis
• Pulmonary edema
• Reactive Airway Disease Syndrome

Crackling (rales)

This is a series of short, explosive sounds. They may sound like bubbling, rattling or clicking. They mostly occur during inhalation and sometimes during exhalation.

Crackles can be a sign that there’s fluid in the lungs.

They can be caused by: 

• Pneumonia
• Heart disease
• Lung fibrosis
• Cystic fibrosis
• COPD
• Lung infections 
• Asbestosis (caused by breathing in asbestos) 
• Pericarditis  (infection of the covering of the heart)  

Stridor

This a harsh, noisy, squeaking sound happens with every breath. It can be high or low and usually a sign that there is obstruction of the airways. It may be present during inhalation or exhalation. It can be a sign of a life-threatening problem that needs medical attention right away.

The causes of stridor are:

• Laryngomalacia (softening of the vocal cords in babies)
• Paralyzed vocal cord
• Narrow voice box
• Hemangioma (unusual growth of blood vessels) just below the vocal cords
• Infection of the trachea (windpipe)
• Epiglottitis 
• Foreign body stuck in the trachea

Rhonchi

These are low-pitched wheezing sounds that sound like snoring. They usually occur during exhalation. They can be a sign that the bronchial tubes (the tubes that connect the trachea to the lungs) are thickened because of mucus.

Rhonchi sounds can be a sign of bronchitis or COPD.

Whooping

This is a high-pitched gasp that typically follows a long bout of coughing.  It may be a symptom of whooping cough (pertussis), a contagious infection in the respiratory system. 

Pleural friction rub

The membranes that cover the walls of the chest cavity and the outer surface of the lungs are called pleura. If they get inflamed and rub together, it produces a rough, scratchy sound.

It can be a sign of pleurisy (inflammation of the pleura), fluid in the lungs, pneumonia or lung tumors.

Mediastinal crunch

This sound, also called Hamman’s sign. It indicates that air is trapped in the space between the lungs (the mediastinum). It’s a crunchy, scratchy sound and occurs along with the heartbeat.

The sound can occur in lung diseases like COPD, pneumonia or cystic fibrosis.