Andersons pediatric cardiology 599
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Spirometry
Essentialmeasurementsincludebasicinspiratoryandexpiratoryflowvolume
loopsandassessmentofmaximalvoluntaryventilation.Maximalvoluntary
ventilationismeasuredbythesprintmethodasoutlinedbytheAmerican
ThoracicSociety,whereinmaximalventilationismeasuredforanintervalof10
to15secondsandextrapolatedto1minute.47Spirometryisusedtoidentify
patternsofobstructiveorrestrictivepulmonarydiseasethatcouldimpair
exerciseperformance.Postexercisespirometryisusefulforidentifyingpatients
withexercise-inducedbronchospasm.Maximalvoluntaryventilationisusedin
theassessmentoftheremainingpulmonarycapacityattheendofexercise,the
breathingreserve.Asalreadydiscussed,thisisthefractionofthecapacityofthe
pulmonarysystemtoincreaseminuteventilationthatremainsatmaximal
exercise,withnormalvaluesrangingfrom20%to50%.Insituationsoftesting
wherethemaximalvoluntaryventilationsprintmethodisnotfeasible,itmaybe
estimatedusinganyoneofthefollowingequations:
48
49
50
whereMVVismaximalvoluntaryventilation,andFEV1isforcedexpiratory
volumein1second.
Althoughwidelyacceptedasaccurateinhealthyadults,notalltheprevious
equationshavebeenvalidatedinhealthychildren,albeitthefirstequationhas
beenvalidatedinhealthyAfrican-Americanadolescentgirls.Therefore,
wheneverpossible,maximalvoluntaryventilationshouldbedeterminedusing
thesprintmethodasrecommendedbytheAmericanThoracicSociety.
BloodPressureMonitors
Monitoringofbloodpressurecanbeasignificantproblemduringexercise
testingduetoartifactfrommotionofthearm,makingaccuratemeasurements
difficulttoobtain.28Thisisagreaterproblemwithtreadmillthanwithcycle
ergometry.Automatedsystemsdesignedforexercisetestingincorporatinga
sensitivemicrophonepositionedoverthebrachialarteryarecurrentlycommonly
usedinmanylaboratories.Manyofthesesystemssimultaneouslyreceivean
electrocardiographicsignal,allowingprecisegatingtotheQRScomplexwhile
filteringbackgroundnoise.Thesesystemsgenerallymeasurepressureboth
oscillometricallyand,usingheadphones,bydirectauscultation.Direct
auscultationisthepreferredmethodbecausethereisatendencytooverestimate
systolicandunderestimatediastolicpressureswithoscillometricmeasurements.
Severalsizesofbloodpressurecuffsarenecessaryequipment.32Mostautomated
systemsalsohavepediatric-sizedcuffs,aswellasoversizedcuffsforlarge
subjects.
PulseOximeters
Pulseoximetersfittedforthefingerorearareusedtomeasurearterialoxygen
saturation.Thedevicescanbeinaccurate,particularlyathighratesofwork,
whenchildrenarepronetograspthecyclehandlebarstootightly.28Therefore
earoximetryisbetterforlaboratoriesusingprimarilycycleergometry.All
oximetersarelessaccurateathigherratesofwork,duetoexcessivemotion.28
IndicationsforExerciseTesting
Indicationsforexercisetestingdependuponsymptomsand/orthepresenceof
cardiovasculardisease.TheAmericanHeartAssociationissuedguidelinesfor
indicationsforstresstestinginchildren(Box23.2).32Wewilldiscusssomeof
themorecommonreasons.
Box23.2
IndicationsforPerforminganExerciseTest
1.Evaluatespecificsymptomsorsignsinducedbyexercise.
2.Identifyabnormaladaptiveresponsestoexerciseincardiacornoncardiac
disorders.
3.Assesstheeffectivenessofmedicalorsurgicalinterventions.
4.Assessfunctionalcapacityforvocational,recreational,andathletic
recommendations.
5.Understandprognosisforaspecificdisorder.
6.Evaluateoverallphysicalfitness.
7.Establishbaselinedataforfollow-upofrehabilitationprograms.
ModifiedfromWashingtonRL,BrickerJT,AlpertBS,etal.Guidelinesfor
exercisetestinginthepediatricagegroup.FromtheCommitteeon
AtherosclerosisandHypertensioninChildren,CouncilonCardiovascular
DiseaseintheYoung,theAmericanHeartAssociation.Circulation.
1994;90:2166–2179.
EvaluationofOverallExercisePerformancein
StructuralHeartDisease
Evaluationoftheoverallperformanceofthecardiovascular,pulmonary,and
musculoskeletalsystemsinchildrenwithstructuralheartdiseasemaybethe
mostcommonindicationfortesting.Thegoalsofsuchevaluationsprimarily
consistofidentifyingpotentialcausesofexerciseintolerance,stratificationof
