A pleural friction rub is a loud, coarse, grating, creaking, or squeaking sound auscultated over one or both lungs, typically during late inspiration or early expiration. It is best heard over the low axilla or the anterior, lateral, or posterior lung bases with the patient sitting upright. The sound may be intermittent and can resemble crackles or a pericardial friction rub.

A pleural friction rub indicates inflammation of the visceral and parietal pleura, causing congestion and edema. Fibrinous exudate covers both pleural surfaces, displacing the normal pleural fluid and leading to rubbing of the surfaces during respiratory movements.

Pathophysiology

The pathophysiology of a pleural friction rub involves pleural inflammation. Inflammatory processes — due to infection, autoimmune disease, trauma, or neoplasm — increase vascular permeability, leading to edema and fibrin deposition between the visceral and parietal pleura. This fibrinous exudate reduces the lubricating pleural fluid, causing the two layers to rub during respiration. The characteristic sound arises from the mechanical friction of inflamed pleural surfaces, usually accentuated during deep inspiration and early expiration.

Emergency Interventions

When a pleural friction rub is detected, assess for respiratory distress:

• Shallow or decreased respirations

• Crowing, wheezing, or stridor

• Dyspnea and use of accessory muscles

• Intercostal or suprasternal retractions

• Cyanosis and nasal flaring

• Hypotension, tachycardia, and decreased consciousness

If distress is present:

• Open and maintain the airway; consider endotracheal intubation and supplemental oxygen

• Insert a large-bore IV line for fluids and medications

• Elevate the patient’s head to 30°

• Continuously monitor cardiac status and vital signs

History and Physical Examination

History

• Ask about chest pain: location, severity, radiation, duration, aggravating and relieving factors

• Explore history of rheumatoid arthritis, respiratory/cardiovascular disorders, trauma, asbestos exposure, radiation therapy

• Record smoking history in pack-years

Cultural Cue: Pain perception varies; anxious or highly emotional patients may report more pleuritic pain than stoic individuals.

Physical Examination

• Auscultate lungs with the patient sitting upright, breathing slowly and deeply

• Determine if the rub is unilateral or bilateral

• Assess for absent or diminished breath sounds and whether abnormal sounds clear with coughing

• Observe for clubbing or pedal edema (chronic disorder indicators)

• Palpate for chest motion reduction and percuss for dullness or flatness

Medical causes

Other Causes

Thoracic surgery or radiation therapy can produce a pleural friction rub.

Special considerations

• Monitor respiratory status and vital signs

• Administer antitussives for persistent dry cough (avoid opioids)

• Oxygen therapy and antibiotics may be indicated

• Prepare for diagnostic tests: chest X-ray, CT scan

Patient counseling

• Educate about pain relief measures

• Advise which symptoms require immediate reporting: worsening dyspnea, hemoptysis, chest pain, cyanosis

Pediatric pointers

• In children, a pleural friction rub may appear with grunting respirations, chest pain, or chest protection behaviors

• Usually an early sign of pleurisy

Geriatric pointers

• Elderly patients may perceive pleuritic pain similarly to cardiac chest pain

• Evaluate for comorbidities affecting respiratory function

References

1. Buttaro TM, Tybulski J, Bailey PP, Sandberg-Cook J. Primary care: A collaborative practice. St. Louis, MO: Mosby Elsevier; 2008. p. 444–447.

2. Colyar MR. Well-child assessment for primary care providers. Philadelphia, PA: F.A. Davis; 2003.

3. McCance KL, Huether SE, Brashers VL, Rote NS. Pathophysiology: The biologic basis for disease in adults and children. Maryland Heights, MO: Mosby Elsevier; 2010.

4. Sommers MS, Brunner LS. Pocket diseases. Philadelphia, PA: F.A. Davis; 2012.