Pleural Friction Noise

Pleural friction noise (m.frictionis pleurae), or friction noise of the pleural layers, is a sound that occurs when the pleural layers rub against each other or against the chest wall. This sound can be heard when breathing, coughing, laughing, or other breathing movements.

Pleural friction noise can be observed both in normal conditions and in pathologies of the lungs and pleura. It can be caused by various reasons, including:

1. Accumulation of mucus in the lungs or pleura. When mucus accumulates in the lungs or on the pleural linings, they may rub against each other, causing a rubbing sound.
2. Scarring of the lungs or pleura, which can occur with inflammatory diseases such as pneumonia, tuberculosis or lung cancer.
3. Abnormalities of the lungs, such as cysts or diverticula, which can cause the pleural layers to rub against each other.
4. Pneumothorax, when air enters the pleural cavity and causes friction of the pleural layers.
5. Tumors of the lungs or pleura, which can lead to scarring and friction of the pleural layers.
6. Emphysema, which can lead to an increase in lung volume and the appearance of pleural friction noise when breathing.
7. Chronic obstructive pulmonary disease (COPD), which can cause sputum accumulation and a pleural friction rub when you exhale.
8. Restrictive lung diseases, such as pulmonary fibrosis, in which the lungs become stiff and cannot expand fully, which can also lead to a pleural friction rub.