PulmonaryFunctionTestingRespiratoryDepartmentoftheSecondAffiliatedHospitalofGuangzhouMedicalUniversityHuaxingHuang

ClinicalPraticeofPulmonaryFunctionTestingDiagnosticObjectiveAssessmentMonitoringEvaluationsforDisability/ImpairmentLungvolumeandcapacityVentilationfunctionDiffusionfunctionMechanicsofbreathingMainProgramsofPulmonaryFunctionTestingLungvolumeLungvolumemeansthemaximalvolumeofgascontainedbyalung.Lungvolume=tidalvolume(VT)+inspiratoryreservevolume(IRV)+expiratoryreservevolume(ERV)+residualvolume(RV)Lungcapacity:inspiratorycapacity(IC),vitalcapacity(VC),functionalresidualcapacity(FRV),totallungcapacity(TLC)CurveoflungcapacityIRVERVVTVCRVTLCICFRCVitalcapacityThe

maximum

volume

of

air

that

can

beinspired

by

forceful

expiration.ResidualvolumeInspiratoryreservevolume

ExpiratoryreservecapacityTotallungcapacityTidalvolume

FunctionalreservevolumeTidalvolume(VT)The

volume

of

air

inspired

or

expired

with

each

normal

breath.8-15ML/KG

Inspiratorycapacity（IC）

Inspiratoryreservevolume（IRV）IC,the

maximum

volume

of

air

that

can

beinspired

by

forceful

expiration.ItisequaltoVTplusIRV.IRV,the

maximum

extra

volume

of

air

that

be

inspired

over

and

above

the

normal

tidal

volume.Theserevealthemaximamexpansionoflungandchestatstaticstate.

Expiratoryreservevolume(ERV）The

maximum

extra

volume

of

air

that

be

inspired

over

and

above

the

normal

tidal

volume.Itreflectsthepowerofexpiratorymuscleandabdominalmuscle.Vitalcapacity（VC）The

largest

amount

of

air

that

can

be

expired

after

a

maximal

inspiratory

effort

frequently.

VCvariesamongnormalbodies,soratiosofmeasuredVCtopredictedVCareusedforjudgment.Gradingstandard：

ratioofmeasuredVCtopredictedVC

≥80%——normal60-79%——mildlyreduced40-59%——moderatelyreduced<40%——severelyreducedCommondiseaseswithreducedVT

Diseaseswithinjuredlungtissue:

pneumonia,atelectasis,pulmonaryinterstitialfibrosis,pulmonaryedemaRestrictedmovementinthoraxorlung:

thoracocyllosis,obesity,pneumothorax,pleuraleffusion,ascitesAirwayobstruction:

chronicbronchitis,asthma,COPDFunctionalReservecapacity（FRC）The

amount

of

air

that

remains

in

the

lungs

at

the

end

of

normal

expiration.It’sequaltoERVplusRV.Itcanstabilizepartialpressureofalveolus.>FRC%Pred120%increased

FRC<FRC%Pred80%reducedFRC1.CausesforincreasedFRC（1）reducedpulmonaryelasticity：emphysema（2）airwayobstruction：asthma,COPD

2.CausesforreducedFRC（1）injuredlungtissue（2）restrictedmovementinthoraxorlungFunctionalReservecapacity（FRC）Residualvolume（RV）The

air

left

in

the

lungs

after

a

maximal

expiratory

effort.IthavethesamephysiologicalmeaningtoFRC.Totallungcapacity（TLC）The

maximum

volume

to

which

the

lungs

can

be

expanded

with

the

greatest

effort.

It’sequaltoVCplusRV.CommoncausesforreducedTLC:atelectasis,PIF,pneumothorax,pleuraleffusionCommoncausesforincreasedTLC:asthma,emphysemaRatioofRVtoTLC（RV/TLC%）It’susedtogradetheemphysema.RV/TLC%≤35%,normal36-45%,mildemphysema

46-55%,moderateemphysema≥56%,severeemphysema

Ventilationfunction

Pulmonaryventilationmeansthatthe

inflow

or

outflow

of

air

between

the

atmo-sphere

and

the

lung

alveoli.Ventilationfunctionmeasurementincludes:

minuteventilation(MV)

alveolarventilation(VA)

maximalvoluntaryventilation(MVV)

timedvitalcapacity(TVC)Minuteventilation(MV)MVmeansthegasvolumeinhaledorexhaledinoneminute.It’sequaltoVTmultiplybyrespiratoryrate.

MV

=VT×RRAtstaticstate,MVrangesfrom5to8L.MV>10LhyperventilationMV<3Lhypoventilation

Alveolarventilation(VA)

Theamountofairreachingthealveoliperminuteatrest.Anatomicdeadspace:the

space

in

the

conducing

zone

of

the

airways

occupied

by

gas

that

does

not

exchange

with

blood

in

the

pulmonary

vessels,suchasthespaceinnoseandpharynx.Alveolardeadspace:someofthealveolithemselvesarenonfunctionaloronlypartiallyfunctionalbecauseofabsentorpoorbloodflowthroughadjacentpulmonarycapillaries.Physiologicaldeadspace（VD）=

Anatomicdeadspace+Alveolardeadspace.VA=（MV—VD）×RRVAvariesinbodiesandrangesfrom3to5.5L.

VAreflectstheeffectiveventilation.ReductionofMVVandincreaseddeadspacewillresultinalveolarhypo-ventilation.Deadspacethatresultsfromdeepandslowbreathingislessthanthatofshallowandrapidbreathing.SolessrespiratoryrateandmoreVTwillbebetterforVA.Alveolarventilation(VA)

Maximalvolumtaryventilation（MVV）Thetotalamountofnewairmovedintotherespiratorypassagesbydeepestandfasterbreathingineachminute.

Itdependsonlungvolume,complianceoflungandthorax,airwayresistanceandrespiratorymuscle.≥MVV%Pred80%normalDamagegrading：

MVV%Pred60-79%——mildlyreduced

40-59%——

moderatelyreduced<40%——

severelyreduced

Increasedairwayresistance:asthma

Thoracicdeformityorneuromusculardiseases:kyphoscoliosis,Guillian-Barresyndrome

Diseasesoflungtissue：pulmonaryedema

MaincausesofreducedMVVTimedVitalCapacity(TVC)FVCFEV1FEV1/FVC%MMEFPEFTimedVitalCapacity(TVC)FVC(forcedvitalcapacity):Thisistheamountofairexpelledfromthelungsafterfirstfillingthelungstomaximumextentandthenexpiringrapidlyandforcefully.FEV1(forcedexpiratoryvolumeinonesecond)istheamountthatcanbegotinthefirstsecondwhenFVCismeasured.FEV1/FVC%：ratioofFEV1toFVCTimedVitalCapacity(TVC)MMEF(maximalmid-expiratory)：AfterFVCdividedintofouraverageparts,dividetheamountofthetwomiddlepartsbythecorrespondingexpiratorytime,MMEFwillbegot.

TimedVitalCapacity(TVC)FVC%Pred≥80%FEV1%Pred≥80%FEV1/FVC≥70%-80%FEV1%Predcanbeusedtoevaluatethedamagedegreeofventilationanddifferentiateobstructiveventilationdysfunctionfromrestrictiveventilationdysfunction.Time－Volumecurvetime（s）012

345abcVolume(l)FEV1FVCRVTLCSVC

FVCnormalrestrictiveobstructive

ClinicalSignificanceInnormalbody,FVCisclosedtoVC.Increasedintrapleural

pressuremakessmallairwaycloseinearlierstageofexpiration.Atthissituation,FVCislessthanVC.IthappenstopatientswithCOPD.Evaluateventilationdysfunction：

obstructivediseases:FEV1/FVC%reduced,flatcurverestrictivediseases:FEV1/FVC%normalorincreased,gradientcurveGradingClassificationofVentilationFunctioninCOPD(bronchialdilatorused)

levelFEV1/FVCFEV%PredI≤70%≥80%II≤70%50%≤FEV%Pred≤80%III≤70%30%≤FEV%Pred＜50%IV≤70%＜30%or＜50%,chronicrespiratoryfailurePEF(peakexpiratoryflow)Themaximalflowduringaforcefulexpiration.PEFshouldbemeasuredinthemorning,afternoonandbeforesleeping.PEFR=（PEFmaximum-PEFminimum)×2

PEFmaximum+PEFminimumPEFhelptoevaluatethechageofairwayresistance.

×100%ClassificationofventilationdysfunctionObstructiveventilationdysfunctionRestrictiveventilationdysfunctionMixedventilationdysfunctionCharacteristicsofventilationdysfunctionobstructiverestrictivemixedLungcapacityVCNor↓↓↓↓FRC↑↑↓↓unsureTLCNor↑↓↓unsureRV/TLC↑unsureunsureobstructiverestrictivemixedFEV1↓↓↓↓↓FEV1/FVC↓↓Nor↑Nor↓MVV↓↓↓↓↓MMEF↓↓↓↓↓CharacteristicsofventilationdysfunctionDiffusionfunctionGasexchangefunctionmeansthecourseofgasexchange,includingtheexchangeofO2andCO2betweenalveolusandblood,bloodandhistocyte.Itinvolveslungventilation,bloodperfusion,ventilation-perfusionratioanddiffusionfunction.Diffusionfunctioncanbemeasuredtoevaluategasexchangefunctiontosomeextent.DiffusionfunctionThegasexchangebetweenalveolusandbloodcapillaryfromthehighpartialpressuresidetothelowside.Relativefactors:molecularweight,solubility,gaspartialpressuregradient,diffusionarea,diffusiondistance.GasExchangePO2＝104mmHgPCO2＝40mmHgPO2＝104mmHgPCO2＝40mmHgPO2＝40mmHgPCO2＝45mmHg

Clinicalsignificance

Factorsthatcanreducethecapacityofdiffusion:Reducedeffectivediffusionarea:atelectasis,airwayobstruction,pulmonaryembolism

Increaseddiffusiondistance:PIF,pulmonaryedema,sarcoidosis,alveolarcellcarcinomaThecapacityofdiffusionalsodependsongaspartialpressure.

Flow—Volumecurve(F-Vloop)It’sarecordaboutthecoursethattakearapidexpirationtotheextentofRVafteramaximalinspirationtotheextentofTLC.

TheflowrisesrapidlyatthebeginningofforcefulexpirationandreachesthepointofPEFsoon.WiththereductionofVC,theflowgoesdownperpendicularlyalmost.

PEFandVmax75reflectthemainairwayresistanceandrespiratorymusclestrength.Vmax50andVmax25reflectsmallairwayresistance.

Descendingbranchsinkstothevolumeaxisinobstructivediseases,butVCmaynotreduce.Inrestrictivediseases,thecurvesrisesharplyandthedescendingbranchessinknearlyperpendicularly.