How is pleural friction rub defined?

A pleural friction rub is defined as a coarse grating, raspy, or crunching sound that occurs when the pleural layers of the lungs become inflamed and rub against each other during respiration. This sound is typically heard through a stethoscope during inhalation and exhalation and is indicative of underlying conditions such as pleuritis or pleurisy. The coarse quality of the sound distinguishes it from other respiratory sounds, making it important for clinicians to identify during physical assessments.

In contrast, the other options describe different types of breath sounds that do not accurately represent a pleural friction rub. A whistling sound is characteristic of wheezing, which indicates narrowing of the airways. A loud, continuous sound might refer to stridor, suggestive of upper airway obstruction, while a soft, muffled sound could be associated with diminished breath sounds due to various reasons such as fluid accumulation or lung tissue abnormalities. Recognizing the distinct features of a pleural friction rub is crucial for effective diagnosis and management of respiratory conditions.