Pearls of Knowledge: Friction Rubs

Assessment: Friction Rubs 

Pearls of Knowledge          ©

Friction rubs are dry, cracking, and grating sounds caused by inflamed, roughened surfaces rubbing together. Due to the irritation in pericarditis and pleurisy, effusions will develop, and the friction rub will no longer be heard. The friction rub, heard early in the course, may be transient in both conditions and can cause significant pain. 

Pericardial friction rub

  • Heard during S1 and S2.
  • Heard during inhalation and exhalation.
  • Loudest at the apex and left sternal border.
  • Heard best in the left lateral position or when leaning forward.
  • Will be present in pericarditis and cardiac contusion.

Pleural friction rub

  • Heard only on inhalation.
  • Will be present in pleurisy and pulmonary embolus with pulmonary infarction. 


So, the next time you hear a “grating” sound in the chest during your assessment, have the patient hold their breath. In pericarditis it will persist with breath holding. It will disappear (in additional to a pleural friction rub) as an effusion develops.


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