EVALUATING PULMONARY FUNCTION STUDIESAll studies are listed as % of predicted

TEST RESTRICTIVE OBSTRUCTIVE IMPAIRED GASEXCHANGE

Class 0 - Normal VC ≥ 80 ≥ 80 ≥ 80FEV1 ≥ 80 ≥ 80 ≥ 80FEF5 0 ≥ 80 ≥ 80 ≥ 80FEF 25-75 ≥ 70 ≥ 70 ≥ 70FRC < 135 < 135 < 135RV 120-80 120-80 120-80RV/TLC < 35 < 35 < 35DLco ≥ 80 ≥ 80 ≥ 80

Class I – Mild Defect VC < 80-70 ≥ 80 ≥ 80FEV1 ≥ 80 < 80-65 ≥ 80FEF5 0 ≥ 80 < 80-65 ≥ 80FEF 25-75 ≥ 70 < 70-60 ≥ 70FRC < 135 < 150-135 < 135RV 80-120 < 150 120-80RV/TLC < 35 < 40-35 < 35DLco ≥ 80 ≥ 80 < 80 - 65

Class 2 – Moderate Defect VC < 70-55 ≥ 80 Slightly ↓FEV1 ≥ 80 < 65-45 ≥ 80FEF5 0 ≥ 80 < 65-45 ≥ 80FEF 25-75 ≥ 70 < 60-40 ≥ 70FRC 80-120 < 175-150 120-80RV N or reduced < 200-150 120-80RV/TLC < 35 < 50-40 < 35DLco Often reduced ≥ 80 < 65-50*

Class 3 – Severe Defect VC < 55-30 Slightly ↓ < 80-50FEV1 ≥ 80 < 45-20 ≥ 80FEF5 0 Slightly ↓ < 45-20 Slightly ↓FEF 25-75 < 70 -60 < 40-15 Slightly ↓FRC Reduced < 190-175 120-80RV < 80 > 200 120-80RV/TLC 35-40 < 55-50 < 35DLco Reduced Reduced < 50-25*

TEST RESTRICTIVE OBSTRUCTIVE IMPAIRED GASEXCHANGE

Class 4 - Very Severe or Far Advanced Defect VC < 30 Mod. reduced < 50FEV1 N or Slightly ↓ < 20 ≥ 80**FEF5 0 Reduced < 20 ReducedFEF 25-75 < 60 < 15 ReducedFRC Reduced ≥ 190 ≤ 80RV ≤ 80 ≥ 200 ≤ 80RV/TLC 35-40 ≥ 55 ≤ 35DLco ≤ 50 ≤ 50 < 25

* at rest and exercise** except with heart failure

Diagnosis of Asthma: Must have a 10% improvement of FEV1.0 after bronchodilator(FEV1.0 must increase by 200 ml For the 10% range to be valid.)

Adapted from: William F. Miller. Laboratory Evaluation of Pulmonary Function.Lippincott,, ist Ed. 1987.