From the Guidelines
Pleural effusion is typically characterized by decreased or absent breath sounds over the affected area of the lung. When examining a patient with suspected pleural effusion, you'll notice diminished breath sounds, decreased vocal fremitus (vibration felt when the patient speaks), and dullness to percussion over the fluid-filled area, as suggested by the BTS guidelines for the management of pleural infection in children 1. These findings occur because the accumulated fluid in the pleural space creates a barrier that dampens sound transmission. The extent of decreased breath sounds correlates with the amount of fluid present - larger effusions cause more significant sound reduction. Some key points to consider when assessing lung sounds in pleural effusion include:
- Decreased chest expansion
- Dullness to percussion
- Reduced or absent breath sounds, as noted in the guidelines 1
- Assessment of severity, including measurement of oxygen saturation, with levels below 92% indicating severe disease 1 Above the effusion level, you may hear bronchial breathing or egophony (an "E" to "A" change when the patient speaks) due to compressed lung tissue. Sometimes, a pleural friction rub might be audible as the inflamed pleural surfaces rub against each other, though this is more common before significant fluid accumulates. These characteristic lung sound changes help differentiate pleural effusion from other respiratory conditions and guide further diagnostic testing such as chest X-ray, ultrasound, or thoracentesis.
From the Research
Lung Sound in Pleural Effusion
- Pleural effusion is a condition where fluid accumulates in the pleural space, and it can affect lung sounds 2.
- The leading causes of pleural effusion in adults are heart failure, infection, malignancy, and pulmonary embolism, which can all impact lung sounds 2.
- Small bilateral effusions in patients with decompensated heart failure may not require diagnostic thoracentesis, but can still affect lung sounds 2.
- Point-of-care ultrasound can be used to evaluate the pleural space and guide thoracentesis, which can help identify changes in lung sounds 2.
- There is no direct evidence on the specific lung sounds associated with pleural effusion, but studies suggest that the condition can cause changes in breathing sounds 3, 2.
Diagnostic Approach
- The patient's history and physical examination should guide the evaluation of pleural effusion, including the assessment of lung sounds 2.
- Chest radiography and ultrasonography can be used to evaluate the pleural space and detect pleural effusions, which can affect lung sounds 2.
- Diagnostic thoracentesis can be used to differentiate exudates from transudates, and to identify the underlying cause of the pleural effusion, which can impact lung sounds 2.
- Light's criteria can help differentiate exudates from transudates, and pleural aspirate should be evaluated using various tests, including Gram stain, cell count with differential, and culture 2.