Can lung sounds be diminished at the bases and congested in the upper lobes?

Lung Sound Patterns in Pulmonary Disease

Yes, lung sounds can be diminished at the bases and congested in upper lobes, which is a characteristic pattern seen in certain pulmonary conditions, particularly idiopathic pleuroparenchymal fibroelastosis (PPFE) and some forms of interstitial lung disease.

Pathophysiological Basis

Diminished lung sounds at the bases with congestion in the upper lobes can occur due to several mechanisms:

• Pleuroparenchymal fibroelastosis (PPFE): This rare condition involves fibrosis of the pleura and subpleural lung parenchyma predominantly in the upper lobes, leading to dense subpleural consolidation with traction bronchiectasis, architectural distortion, and upper lobe volume loss 1.

• Distribution of pathology: In PPFE, the fibrosis is elastotic with intraalveolar fibrosis present primarily in the upper lobes, while the lower lobes may have diminished sounds due to reduced airflow 1.

• Combined patterns: Some patients present with a combination of PPFE in the upper lobes and usual interstitial pneumonia (UIP) pattern in the lower lobes, creating this distinctive auscultatory finding 1.

Clinical Significance

This pattern of lung sounds has important diagnostic implications:

Upper Lobe Findings

• Congested sounds in upper lobes may represent:
  • Dense subpleural fibrosis
  • Traction bronchiectasis
  • Architectural distortion
  • Consolidation patterns (as seen in organizing pneumonia)

Lower Lobe Findings

• Diminished sounds at bases may indicate:
  • Reduced airflow due to restrictive changes
  • Early fibrotic changes before they become audible
  • Pleural thickening

Specific Conditions Associated with This Pattern

1. Idiopathic Pleuroparenchymal Fibroelastosis (PPFE)

   • Presents with dense subpleural consolidation in upper lobes
   • CT shows traction bronchiectasis and upper lobe volume loss
   • May have normal or diminished sounds at bases 1
   • Disease progression occurs in 60% of patients with 40% mortality 1

2. Combined PPFE and UIP Pattern

   • Shows dense subpleural fibrosis at lung apices with traction bronchiectasis
   • Subpleural reticular abnormality and honeycombing in lower lobes 1
   • Creates the clinical picture of congested upper lobes with diminished basal sounds

3. Acute Fibrinous and Organizing Pneumonia (AFOP)

   • Can present with peribronchovascular and basal predominant consolidation
   • May have areas of diminished sounds interspersed with areas of congestion 1

4. Other Interstitial Lung Diseases

   • Some forms of hypersensitivity pneumonitis can have upper lobe predominance
   • Certain connective tissue disease-associated ILDs may present with this pattern 1

Diagnostic Approach

When encountering this auscultatory pattern:

1. Imaging is essential:

   • High-resolution CT (HRCT) is the gold standard for detailed evaluation 2
   • Look for dense subpleural fibrosis at the lung apices with traction bronchiectasis and upper lobe volume loss 1
   • Assess for subpleural reticular abnormality and honeycombing in lower lobes

2. Pulmonary Function Testing:

   • Often shows restrictive pattern
   • Forced oscillation technique may show increased respiratory resistance (Rrs) and decreased respiratory reactance (Xrs) 1

3. Consider lung biopsy if diagnosis remains unclear:

   • Transbronchial lung cryobiopsy (TBLC) may be considered as an alternative to surgical lung biopsy 1
   • Histology may show pleural thickening and subpleural fibrosis with dense masses of elastic fibers 1

Clinical Pearls and Pitfalls

Pearls:

• This pattern is relatively uncommon but highly suggestive of specific pathologies
• PPFE has been associated with recurrent infections and pneumothorax 1
• Early recognition is important as disease progression occurs in a majority of patients

Pitfalls:

• Normal physical examination can be present in mild interstitial lung disease, with signs becoming apparent only as disease progresses 1
• Lung sounds alone are insufficient for diagnosis and must be correlated with imaging findings
• This pattern can be missed if auscultation is not performed systematically over all lung fields

Conclusion

The finding of diminished lung sounds at the bases with congestion in the upper lobes represents a distinctive pattern that should prompt consideration of specific diagnoses, particularly PPFE or combined PPFE/UIP pattern. This auscultatory finding warrants further investigation with high-resolution CT imaging to characterize the underlying pathology and guide appropriate management.