Evaluation of Pulmonary Function Testing

Last updated: April 6, 2026, 11:12 PM Pacific Time (PDT)

Interactive teaching tool for spirometry, lung volumes, DLCO, bronchodilator response, and likely physiologic patterns.

Interactive PFT interpreter

activate assistant

Spirometry FEV1/FVC ratio
FEV1/FVC LLN, if available
FEV1 (% predicted)
FVC (% predicted)

Lung volumes TLC (% predicted)
RV/TLC (% predicted or z-score note)
Air trapping or hyperinflation reported

Diffusion DLCO (% predicted)
KCO / DLCO-VA
Hemoglobin correction

Bronchodilator response Pre-BD FEV1 (L)
Post-BD FEV1 (L)
Predicted FEV1 (L)
Quality concern / poor effort noted

Use LLN/z-scores when available; fixed cutoffs can misclassify older or younger patients.
Obstruction is low FEV1/FVC; restriction requires low TLC, not low FVC alone.
Low FVC with normal ratio can be restriction, air trapping, poor effort, obesity, or a nonspecific pattern.
Bronchodilator response per 2022 ERS/ATS is a change >10% of predicted value.
DLCO helps separate emphysema, ILD, pulmonary vascular disease, anemia, and extrapulmonary restriction.