What sound is an abrasive noise made by inflamed serous surfaces rubbing together during the respiratory cycle?

The sound described as an abrasive noise made by inflamed serous surfaces rubbing together during the respiratory cycle is known as a pleural friction rub. This phenomenon occurs when the pleura, the membranes surrounding the lungs, become inflamed, typically due to conditions like pleuritis or pleurisy. The inflammation causes the two layers of the pleura to rub against each other, generating a characteristic scratching or grating sound that can be heard during auscultation of the chest.

This sound is typically audible during both inspiration and expiration, and it can be distinctly localized to the area of inflammation. Recognizing a pleural friction rub is important as it provides insight into the underlying pathology affecting the pleura, differentiating it from other respiratory sounds that indicate different conditions, such as wheezes or rhonchi, which are typically associated with bronchial obstruction or secretions.