It’s interesting how much you can learn with a review of the most basic skills. As nurse practitioners, many of us have been listening to lung sounds for years. But, when a reader asked me to post a refresher on auscultation, even as an experienced NP I came away with a few new interesting tidbits of information. So, whether you’re new to the nurse practitioner profession, or you’re a seasoned NP with years of experience, check out this super quick refresher on lung sounds.
When you examine a patient, as you auscultate the lungs, you’re looking to see if the lung sounds are normal. What’s normal you ask?
Normal Lung Sounds
Normal, or vesicular, lung sounds are soft and low-pitched in quality. Although physiologically expiration is longer than inspiration, upon auscultation it will be shorter. When you auscultate the lungs you should hear a 3:1 inspiration to expiration ratio. This is because air moves out of the alveoli, towards the central airway during expiration. So, when you auscultate the lung fields, you can’t hear the entire expiratory process.
In the case of pulmonary or airway pathology, you may hear abnormal, or adventitious, lung sounds. What kinds of adventitious sounds might you notice?
Crackles, or rales, are short, popping sounds noted on auscultation of the lung fields. They may be fine or course in quality. Fine crackles are higher in frequency and shorter in duration than coarse crackles and are caused by the sudden opening of a closed airway. Coarse crackles are related to airway secretions.
Crackles are best heard on inspiration, although they may be noted throughout the respiratory cycle. The number of crackles noted on exam directly correlates with disease severity. The greater the number of crackles, the more advanced the disease or illness. Crackles may be auscultated in a number of medical conditions including, but not limited to, pneumonia and COPD.
Ronchi are low-pitched, continuous sounds, with a snoring or rattling quality. They are created by vibration of the walls of the airway and/or the rupture of fluid films. Ronchi tend to resolve with coughing. These sounds are associated with disorders that cause increased airway secretions or reduced clearance of airway secretions.
Wheezes are high or low-pitched sounds with a musical quality that occur in the inspiratory and/or expiratory phases of the respiratory cycle. High-pitched wheezes have a squeaking quality, while low-pitched wheezes have a snoring or moaning quality. Wheezing is caused by airway constriction or narrowing, and is not usually affected by coughing. The degree of wheezing is not always correlated with disease severity. Wheezing is caused by conditions such as infection (croup, bronchiolitis), asthma, COPD, pulmonary edema, and foreign body aspiration.
Stridor is a high-pitched, continuous sound heard over the trachea. It occurs as a result of turbulent flow in the upper airway caused by obstruction. Stridor is louder than wheezing and is more prominently heard during inspiration. Croup is the most common cause of stridor in young children. Other common causes of stridor include foreign body aspiration, retropharyngeal abscess, peritonsillar abscess, allergic reaction, and epiglottitis.
Still unsure about lung sounds? Check out this video for some audio auscultation practice.