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Lung Function Tests
 
Lung Function Tests
 

Restrictive Lung Disease

 
 
 
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Overview

  • While spirometric values such as FEV₁ and FVC can be suggestive of restrictive lung disease,  a reduced total lung capacity (TLC) of 80% predicted is diagnostic.
    • Pulmonary Function Test Findings

    • FEV₁ reduced (<80% predicted)
    • FVC reduced (<80% predicted)
    • FEV₁:FVC ratio normal (>0.7)
    • Reduced volume in flow-volume loop
    • TLC <80% predicted
    • DLCO normal (extrapulmonary) or decreased (parenchymal)
    • Causes of Restrictive Disease

    • Parenchymal

    • Pulmonary fibrosis
    • Sarcoidosis
    • Atelectasis
    • Extrapulmonary

    • Pleural - pleural effusion, pneumothorax
    • Chest wall deformity - kyphosis, scoliosis, morbid obesity
    • Neurologic / neuromuscular / muscular disorder - motor neurone disease, Guillain-Barre, muscular dystrophy, myasthenia gravis
    • Severity of Restrictive Disease

      Based on TLC:
    • Mild - 70-80% predicted
    • Moderate - 60-70% predicted
    • Moderately severe - 50-60% predicted
    • Severe - <50% predicted
 
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