PulmonaryFunctionTestingRamezSunnaMD,FCCP

LectureOverview

• GeneralIntroduction• IndicationsandUses• Technicalaspects• Interpretation• PatternsofAbnormalities

WhentoperformaPFT1. Evaluationofapulmonarycomplaintorsigntoassessforanyimpairmentinfunction

2. Quantificationofaknownimpairment(whetherpartofinitialeval.orfollowup/assessingdz.progression)

3. Preoperativeassessment4. Disabilityevaluation5. Screenpeopleexposedtoinhalational/toxic

agentsordrugeffects

Caution• Myocardialinfarctionwithinthelastmonth• UnstableAngina• RecentThoraco-abdominalsurgery• Recentophthalmicsurgery• ThoracicorabdominalAneurysm• CurrentPneumothoraxWildeM,NairS,Madden B.PulmonaryFunctiontests- areview.CareoftheCrit Ill.2007;Dec23(6):173-7

PFT- Components• Spirometry• Bronchodilatorchallenge• LungVolumes• DLCO• MaximalRespiratoryPressures• MaximalVoluntaryVentilation• Bronchoprovocation

LungVolumes

Volume-TimeSpirogram• Tidalvolumerespirations

• Atendexpirationpt.performsamaximalinspirationfollowedby

• Exhalationashardandfastaspossible

• ExhalingtheFVC

Volume (L )

FVC

RV

Volumetimecurve Flowvolumeloop

EquipmentPerformance

QualityControl

PatientManeuvers

AcceptabilityCriteria

ReproducibilityCriteria

TestsforAnalysisReferenceValuesInterpretation

• Volumeswithin±5%or50ml;flowswithin±5%or200ml/s

• Checkaccuracy&linearitydailywith3Lsyringe

• Explainanddemonstratemaneuver;properpatientposition;repeattestsuntil3acceptabletestsorpatienthasmade8attempts

• Goodquickstartwithvigorouseffort;nocoughorpauseinfirstsec;6secminimumorgoodplateauwithoutglottic closure

• For3acceptabletests,differencebetweenlargesttwoFVC’sandlargesttwoFEV1’sshouldbewithin150mlofeachother

• AnalyzelargestFVCandFEV1fromacceptabletests&selectappropriatereferencevalues

• Useestablishedguidelinesforinterpretation

GeneralApproachtoInterpretingaPFT• Confirmdemographicdata• IsthetestAcceptable/Reproducible• Aretheresultsnormal• Whatisthepatternofabnormality• Whatistheseverityofabnormality• Whatdoesthismeanforthepatient-comparisontoprevioustests

PitfallsandErrorsinFlowVolumeLoops• FlowVolumeloopisusefulinassessingacceptabilityofthemaneuvers:

1. Lackofearlypeaksuggestpooreffort.

2. Suddentailingoffofexpiratorylimb/stoppedblowingtooearly/earlyglottic clsoure

3. CoughSource:emedicine.com

VariableEffortCough

NormalValues• AppropriateReferenceStandardsmustbeusedforcomparison• BasedonAge,Height,SexandRace• IntheUS:NHANESIIIstandardforadults• DifferentadjustmentfactorsfordifferentvaluesforCaucasian,AfricanAmerican,Asian,easternIndian• Shouldbeupdatedatleastevery10years

PercentPredictedasNormalRange• Resultsareexpressedas%Predictedofapredictednormalvalueofapersonthesameage,sex,raceandheight

• NormalRanges:ü FVC>80%

ü FEV1 >80%

ü FEV1/FVClessthan5th percentile(LLN),>0.70

ü FEF25-75:65%;50%

ü DLCO80-120%

ü TLC80-120%

ü RV80-120%

• UseofLLNbelow5thpercentileofthenormaldistributioninsteadof%predicted

PatternsofAbnormality• Obstructivepattern• Restrictivepattern• Mixedpattern• Vascularpattern• Neuromuscularpattern• Pooreffortpattern• NonSpecificPattern

ObstructiveVentilatory Defect• Limitationofexpiratoryflow• ThehallmarkisareducedFEV1/FVCratio<0.7• FEF25-75<?50%

ü Asthmaü COPDü CysticFibrosisü Bronchiectasis

TheFlowVolumeLoop• Theusuallineardescentoftheflow-volumecurveisdisruptedbyanexaggeratedupwardconcavityofthedescendinglimbofthecurve

BronchodilatorResponse• Physiologicresponseinvolvingairwayepithelium,nerves,mediatorsandsmoothmuscle• Bronchodilatortobeheldpriortotesting• IncreaseineitherFEV1orFVCfrombaseline

ü Byatleast12%and200mL• ThecorrelationbetweenbronchoconstrictionandBDresponseisimperfect

RestrictiveVentilatory Defect• ThehallmarkisreducedLungvolumes

• ReducedTLCbydefinition

• Theflowvolumeloopoftenmaintainsanearlynormalshapethoughminiaturized.

Normalvs.Obstructivevs.Restrictive

MixedObstructiveandRestrictivePattern• ReducedFEV1/FVCratiowithareducedTLC• Couldbetwodiseaseprocesses:AmiodaroneDrugToxicityinapatientwithCOPD…• Sarcoidosis,Lymphangiomleiomyomatosis,cryptogenicorganizingpneumonia,langerhans cellhistiocytosis,respiratorybronchiolitis

RatingofSeverity

• Basedonstatement/guidelinesfromtheAmericanThoracicSociety(ATS)- FEV1• ObstructivePattern- FEV1• RestrictivePattern– TLC(lungvolumes)

ü Iflungvolumesnotobtained– FVC

ATS/ERSStandardizationofLungTesting:InterpretativeStrategiesforLungFunctionTests- 2005

IsolatedReductioninDiffusionCapacity• Single-breathDLCOmeasuresthecapacityofthelungtotransfergas

• PatientexhalestoRVthenrapidlyinhalesgasmixturewithaminuteamountofCO.After,10secondbreath-holdatTLC,thepatientrapidlyexhales&theexhaledgasisanalyzedtomeasuretheamountofCOtransferredintothecapillarybloodduringthemaneuver

CausesofDecreasedDLCO• Anemia,highCOlevels

• ObstructiveLungDiseaseü Emphysema

ü CysticFibrosis

• ParenchymalLungDiseaseü InterstitialLungDisease

ü Sarcoidosis

• PulmonaryVascularDiseaseü PrimaryPulmonaryHypertension

ü AcuteandChronicPulmonaryThromboembolism

NeuromuscularPattern• RestrictivepatternwithnormalDLCO

Lungcompliance(microatelectasis)greaterlossofVCwithchronicMuscleweakness

Chestwallcompliance(stiffligaments,ankylosedjoints,kyphoscoliosis)

• ChangeinFVCbetweenuprightandsupineü Normalfall- average8%;upperlimit19%ü >20%fallsuggestsdiaphragmaticparalysis

Estenne M,DeTroyerATheRespiratoryMuscles1990;360AllenSMetalBrJDisChest1985;79:267

MeasurementofMIPandMEP

HyattREetalInterpretationofPulmonaryFunctionTests,LippincottWilliamsandWilkins1997,p90

MaximumAirwayPressures• %predictedvaluesareavailable,decreaseswithage,lowervaluesinfemales

• Variabilityofaround24cmH2Opressuresinsamedaymeasurements

• NormalMIPgood–ve predictivevalue• MIP<1/3NLpredictshypercarbia• MEP<60cmH2Opredictsweakcough• correlatespoorlywithseverityoflimbmuscleweakness

MaximumVoluntaryVentilation

Grippi MAetalPulmonaryfunctiontesting.InFishmanAP,ed PulmonaryDiseasesandDisorders,1988;2nd ed,pp2469-2521

MaximalVoluntaryVentilation• Originallycalledmaximalbreathingcapacity• Themaximalvolumeofairthatcanbemovedbyvoluntaryeffortin1minute• Technique:breatherapidlyanddeeplyfor15to30seconds,ventilatory volumesarerecorded

MVV• Heavilydependentonpatientcooperationandeffort

• Nonspecific:Lossofcoordinationofrespiratorymuscles,musculoskeletaldiseaseofthechestwall,neurologicdisease,anddeconditioningfromanychronicillness,aswellasventilatory defectsdecreaseMVV

• Itcorrelateswellwithsubjectivedyspnea

• Usefulinevaluatingexercisetolerance

• Hasaprognosticvalueinpreoperativeevaluation

• Itprovidesameasureofrespiratorymuscleenduranceandventilatoryreserve

• MVV=FEV1*35-40

NonspecificAirwayDiseasePattern

CentralandUpperAirwayObstruction

• Flowvolumeloopscanprovideinformationonupperairwayobstruction• Characteristicsofthelesion

ü Locationofthelesion:intrathoracicvsextrathoracic

ü Behaviorofthelesioninrapidinspirationandrapidexhalation:fixedvsvariable

FixedObstruction

Trachealstenosis/strictureBilateralvocalcordparalysis

Extrinsiccompression

Levitzky MGPulmonaryPhysiology,McGrawHill4thed,1995,p50

VariableExtrathoracic Obstruction

VocalcordparalysisGoiterTumor

Levitzky MGPulmonaryPhysiology,McGrawHill4thed,1995,p50

VariableIntrathoracicObstruction

TracheomalaciaIntratracheal tumor

Levitzky MGPulmonaryPhysiology,McGrawHill4thed,1995,p50

ThankYou!RamezSunnaMD,FCCPsunnar@health.missouri.edu