1. 0. Look at graph
1. Look for obstruction
 Decrease inFEV1/FVC
2. Look for degree of obstruction
 Decrease inFEV1
 AmericanthoracicSocietyguideline
Degree of obstruction FEV1 value
Mild >70%
Moderate 60-69%
ModeratelySevere 50-59%
Severe 35-49%

2. VerySevere <35%
3. Look for significantBDchanges - Indicative of asthma
 >12% or 200mL change
4. Look for restriction(Note:restrictive diseaserequiresdecreaseinbothFVCandTLC)
 Decrease inFVC
Degree of restriction FVCvalue
Mild 60-80%
Moderate 50-60%
Severe <50%
5. Look at DLCO - indicatesproblemsingasexchange toblood
Degree of gas exchange DLCO value
Mild >60%
Moderate 40-60%
Severe <40%
6. If decrease inDLCOlookat KCO
 DLCO isnot accurate
 KCO- calibratedwithalveolarvolume
 Asthmatic- eithernormal DLCOor low DLCO but normal KCO
 Emphysema- lowDLCO and low KCO
7. Look for gas trappingandhyperinflation
 Gas trapping- increase inRV and/ordecrease inFVC
 Hyperinflation - increase inTLC

3. 8. Look at MIP/MEP (afterrestrictionisconfirmed)
 Decrease inMIP/MEP indicatesneuromusculardisease
 Normal MIP/MEP - Obesity,chestwall
NOTE: normal FVCand normal TLC can indicate non-specificpattern(70% obstructionand30%
restrictive disease)