When auscultating the lungs, a grating sound on inspiration persists after the patient coughs and is louder over the lower lateral anterior surface. Which best explains what the clinician is hearing?

• A. A peripheral friction rub.
• B. Pulmonary crackles.
• C. Pleural effusion.
• D. Bronchial wheezes.

Answer: (A)

A grating, dry, rubbing sound heard during inspiration that persists after coughing and is best over the lower lateral chest is a friction rub from inflamed pleural surfaces. When the lining of the lungs (the visceral pleura) and the chest wall lining (the parietal pleura) become rough and slide against each other, they produce a harsh, creaking sound as air moves in and out. The persistence after coughing helps distinguish it from secretions or fluid-related sounds, and the location matches where the pleura surfaces contact each other most when the lungs expand.

This isn’t a crackle, which comes from the reopening of small airways and often changes with coughing, nor is it a bronchial wheeze, which is a musical, continuous sound typically heard more with expiration. It isn’t pleural effusion alone, which tends to dull or reduce breath sounds and can cause dull percussion rather than a grating rub.