Pearls of Knowledge: Breath sounds

Assessment: Breath Sounds 

Pearls of Knowledge           ©

The evaluation of breath sounds is part of most assessments. As you listen to breath sounds, remember the importance of listening to the front and back of the chest. Anterior assessment allows you to hear the upper lobes and right midlobe. Posterior assessment primarily allows you to hear the lower lobes. 

Chest auscultation 

With assessment, it is important to listen through inhalation and exhalation. The sequence should be side to side and top to bottom. For the elderly, it is recommended to listen to the lower lobes first to maximally hear abnormalities as they may tire with multiple forced breaths. To maximally expand the chest, have the patient lean forward to listen to the posterior chest and lean back to listen to the anterior and lateral chest. 


Crackles are heard on inspiration and indicate fluid, atelectasis, or pneumonia. In left-sided heart failure and pulmonary edema, crackles will be persistent. When crackles are heard in post-operative conditions and pulmonary or fat emboli, they are most often due to atelectasis and will clear with cough and deep breathing exercises. Crackles are heard in bacterial pneumonia, along with bronchial (loud) breath sounds. Crackles are often absent in viral pneumonia. 


Rhonchi are primarily heard on expiration and indicates movement of air through mucus. Rhonchi will be heard when a patient needs to be suctioned. The rhonchi will clear when suctioning is successful. 


Wheezing indicates air movement through narrowed airways or a blockage in the vocal cords. It may be audible on entering the room or it may only be heard on auscultation. Expiratory wheezing indicates a mild obstruction and will be seen in acute situations. Inspiratory wheezing is more often seen in chronic conditions, such asthma patients. In acute asthmatic attacks, wheezing will be inspiratory and expiratory. The absence of wheezing in an acute asthmatic attack indicates a lack of air movement and an emergent situation. 


Stridor is a crowing sound which is typically heard on inspiration and indicates upper airway obstruction. It is assessed by listening over the trachea. The sound will be affected by the location of the obstruction and the degree of the obstruction. 

Location of the obstruction 

When the obstruction is above the glottis, such as in epiglottitis, the stridor will be quiet. When the obstruction is below the glottis, such as in bronchiolitis, it will be loud and rasping. 

Degree of obstruction 

With a mild obstruction, stridor is heard on inspiration. In severe obstruction, stridor is heard on inspiration and exhalation. In complete obstruction, no stridor is heard, and cyanosis develops.

Inspiratory to Expiratory Ratio 

Normal inspiratory to expiratory (I:E) ratio is 1:2. In caring for ventilator patients, this is one of the settings that will be monitored. If the ratio becomes 1:1 or 2:1, the risk of barotrauma (pneumothorax) increases substantially. 

In an acute asthmatic attack, the I:E ratio will be 1:1 due to hypoxia. If the attack does not resolve, air trapping occurs, and the ratio will prolong to 1:3 (or more) indicating a deterioration and possible need to proceed with intubation. 

Clinical Correlations 

Look at these three clinical correlations to apply this knowledge to your practice. 

Correlation #1 

If you have a post-op patient with crackles (and possibly) a low SpO2, do not just increase their oxygen flow rate. Instead, have them cough and deep breath. If the crackles clear with coughing, good nursing care, incentive spirometry, and possibly a breathing treatment are needed. 

Correlation #2 

If you have a patient with chronic bronchitis and shortness of breath, make a valid assessment before you automatically move to suction them. If you hear rhonchi, secretions are present, and suctioning is indicated. After suctioning, rhonchi should have cleared. 

Correlation #3 

If your patient has stridor, be especially concerned when it is heard on inspiration and exhalation. If they suddenly become “quiet”, the obstruction could have advanced, and Rapid Response should be called. 

Correlation #4 

If you have an asthma patient, monitor their wheezing, and look at the inspiratory to expiratory ratio. If exhalation is three (or more) times inhalation, your patient is in trouble due to air trapping and rapid interventions are needed. As the attack progresses, the absence of wheezing is a critical development and indicates the lack of air movement.


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