Reviewed and updated by Megan Doble, DNP, CRNP, FNP-C, AGACNP-C: March 4, 2024

Below are the results of a nursing quiz about lung auscultation. This revealed a need for clarification of common adventitious lung sounds and the commonly associated clinical conditions.   

Different Types of Breath Sounds

Let’s review the most common adventitious lung sounds. Remember, breath sounds are generated by the flow of air in and out of the lungs and should be characterized by pitch, intensity, quality, and relative duration of the inspiratory and expiratory phases.

Wheeze

A wheeze (also referred to as a sibilant wheeze) is a high-pitched continuous musical (whistle-like) sound, which may occur during inspiration and/or expiration, due to a narrowed or obstructed airway.  A longer, higher-pitched wheeze is associated with a higher degree of obstruction. Wheezes are most often heard with bronchospasm in acute asthma exacerbations or flair-ups of acute or chronic bronchitis.

Rhonchi

Alternately, what we often refer to as rhonchi is the “sonorous wheeze,” which refers to a deep, low-pitched rumbling or coarse breath sound as air moves through tracheal-bronchial passages in the presence of mucous or respiratory secretions. They are often more pronounced during expiration and are more likely to be prolonged, continuous, and less discrete than crackles. Rhonchi will sometimes be cleared by cough.

Stridor

Stridor is a high-pitched, monophonic inspiratory sound typically loudest over the anterior neck as air moves turbulently over a narrowing in the upper airway. The presence of stridor indicates upper airway spasm or partial obstruction and may be present in infection, upper airway abscess, foreign body ingestion, or certain congenital anomalies.

Crackles

Crackles, or rales, are short, high-pitched, discrete, discontinuous, popping sounds created by air being forced through an airway or alveoli narrowed by fluid, pus, or mucous. These breath sounds may also be heard when there is a delayed opening of collapsed alveoli. Crackles are not cleared by coughing.

Crackles are typically heard during inspiration and can be further defined as coarse or fine. Coarse crackles are lower-pitched, heard during early inspiration, and sound harsh, loud, or moist. They are caused by mucous in larger bronchioles, as heard in COPD. Fine crackles are higher-pitched, heard during late inspiration, and may sound like hair rubbing together. These sounds originate in the small airways/alveoli and may be heard in interstitial pneumonia or pulmonary fibrosis.

Lung Sounds and Clinical Conditions

Asthma

Asthma is a condition mediated by inflammation. The resulting physiologic response in the airways is bronchoconstriction and airway edema. This response is triggered by an irritant, allergen, or infection. As air moves through these narrowed airways, the primary lung sound is high-pitched wheezing. Initially the wheezes are expiratory but depending on confounding factors or worsening clinical symptoms, there may be inspiratory wheezes, rhonchi, or crackles. For testing purposes, however, expiratory wheezes are associated with asthma.

Pulmonary Fibrosis

Pulmonary fibrosis is a form of interstitial lung disease in which scarring (or fibrosis) is the hallmark clinical feature. This scarring leads to thickness and stiffness in the lungs. The most common adventitious breath sound associated with pulmonary fibrosis is fine bibasilar (lower lobes of both lungs) crackles. This may be hard to distinguish from congestive heart failure. The crackles are the result of the snapping open of collapsed, stiff alveoli.

Neuromuscular Disease

Neuromuscular disorders can cause respiratory problems through several mechanisms as the muscles responsible for breathing are affected. Diaphragmatic weakness can lead to hypoventilation; chest wall muscle weakness can lead to ineffective cough; and upper airway muscle weakness can lead to difficult swallowing and ineffective clearing of upper airway secretions. In general, there are no specific adventitious breath sounds associated with neuromuscular disorders.

Pneumothorax

A pneumothorax is a collapsed lung. There would be loss of breath sounds over the area of a pneumothorax as there is no air movement in the area of auscultation.

So, this leads us to the correct answer. During lung auscultation, crackles are heard in pulmonary fibrosis, which is choice B.  

Reviewing what you know and thinking about each response choice can help you focus in on the correct answer. Do you have an easy acronym or pearl for remembering breath sounds, or some test-taking strategies to share?
 

Breath Sounds References:

Hinkle, J.,Cheever, K., & Overbaugh, K.  (2021). Brunner & Suddarth's Textbook of Medical-Surgical Nursing, 15^th edition. Philadelphia: Wolters Kluwer Health.

Stewart, J.B.J.D.J.F.B.S. R. ([Insert Year of Publication]). Seidel's Guide to Physical Examination (10th ed.). Elsevier Health Sciences (US).

 

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