Pulmonary Function Tests (PFTs)

    • Spirometry: evaluate for obstructive disease
      • Flow-volume loops: diagnose and/or localize obstruction
      • Bronchodilator: indicated if obstruction at baseline or asthma clinically suspected
      • Methacholine challenge: helps dx asthma if spirometry nl, > 20% ↓ FEV1 → asthma
    • Lung volumes: evaluate for hyperinflation or restrictive disease including NM causes
    • DLCO: evaluates functional surface area for gas exchange; helps differentiate causes of obstructive and restrictive diseases and screens for vascular disease & early ILD
    Figure 2-1 Approach to abnormal PFTs