Rasmussen Maternal Child Practice Exam

Crackles are the sound most commonly linked to bacterial pneumonia. They arise when air moves through fluid or exudate in the small airways and alveoli. In pneumonia, inflammation and infection fill these spaces, so as the patient inhales, air bubbles through the fluid and creates a popping, crackling sound, often heard during inspiration. This contrasts with wheezes, which come from narrowed airways and are typical of asthma or COPD; stridor, which signals an upper airway obstruction; and rhonchi, which are coarse sounds from secretions in larger airways and can occur with bronchitis but are not the hallmark of pneumonia.