Pulmonary Function Tests Bookmark SharePulmonary function tests including spirometry, flow-volume loops, lung volumes and diffusion capacity can be used to diagnose and grade obstructive or restrictive lung disease. Try our Lung Function Tests Quiz***Summary of PFT interpretationPatterns of Test FindingsObstructive vs restrictiveObstructive diseaseRestrictive diseaseSpirometryPerforming spirometrySummary of interpretationFEV₁Expired volume in 1 sec80-120%predictedFVCForced vital capacity80-120%predictedFEV₁:FVC Ratio>0.70Post-Bronchodilator Reversibility12% or >200mL increase in FEV1 / FVCGraphsVolume-Time GraphsDeep breath outFlow-Volume LoopsDeep breath out then inLung VolumesSummary of Lung VolumesTotal Lung Capacity (TLC)80-120% predicted80-120%predictedResidual Volume (RV)Functional Residual Capacity (FRC)Other TestsDLCO60-120%predictedBronchial ChallengeUsing histamine or methacholineOn this page: SpirometryGraphsLung VolumesOther Tests