PFT Interpretation

FEV1/FVC + lung volumes + DLCO algorithm.

Select any text to highlight it or make a flashcard.

◆Stepwise algorithm

•Step 1: FEV1/FVC ratio. ≤0.7 = obstructive; >0.7 = restrictive
•Step 2 (obstructive): ↑TLC + ↑RV (air trapping). Test reversibility with albuterol
•Reversible (↑FEV1 ≥12%) = asthma
•Not reversible: ↓DLCO = emphysema; normal DLCO = chronic bronchitis
•Step 2 (restrictive): ↓TLC + ↓RV. Check DLCO
•↓DLCO = intrinsic (pulmonary fibrosis)
•Normal DLCO = extrinsic (obesity, chest wall, NMD)

◆Methacholine challenge: ↓FEV1 ≥20% confirms asthma when reversibility test equivocal
◆Severe asthma exacerbation + rising PCO₂ in hypoxic patient = ominous, anticipate respiratory failure

Done reading?

Track your progress by marking this complete.