Continuous Vs Non Continuous Lung Sounds

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

Answer: B. Crackles are heard when collapsed or stiff alveoli snap open, as in pulmonary fibrosis. Wheezes are commonly associated with asthma and diminished breath sounds with neuromuscular disease. Breath sounds will be decreased or absent over the area of a pneumothorax .

Different Types of Breath Sounds

Let's review the most common adventitious lung sounds.

Wheeze

A wheeze is high-pitched continuous musical sound, which may occur during inspiration and/or expiration, due to an obstructive process. The classic wheeze may be referred to as "sibilant wheeze." This refers to the high-pitched whistle-like sound heard during expiration, typically in the setting of asthma, as air moves through a narrow or obstructed airway.

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.

Stridor

In stridor, you'll hear high-pitched, monophonic inspiratory wheezing. It's typically loudest over the anterior neck, as air moves turbulently over a partially obstructed upper airway.

Crackles

Crackles, or rales, are short, high pitched, discontinuous, intermittent, 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 delayed opening of collapsed alveoli.

Crackles are typically heard during inspiration and can be further defined as coarse or fine. Coarse crackles are heard during early inspiration and sound harsh or moist. They are caused by mucous in larger bronchioles, as heard in COPD.Fine crackles are 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

Now, let's think about test-taking strategies. In this instance, it would be helpful to go through each clinical condition separately and predict what you may hear on auscultation.

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 wheeze. 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 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 pathways 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 not 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 Reference

Hinkle, J. & Cheever, K.  (2013). Brunner & Suddarth's Textbook of Medical-Surgical Nursing. Philadelphia: Lippincott Williams & Wilkins.

More Resources

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Source: https://www.nursingcenter.com/ncblog/october-2016/breath-sounds-test-your-knowledge

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