Andersons pediatric cardiology 1891

RationaleandMetricsforInterstage
Monitoring
RationaleforMonitoring
Avarietyofmechanismshavebeenproposedforinfantdemiseduringthefirst
interstageperiod.Somesingle-centerreportshaveidentifiednonmodifiablerisk
factorssuchasanatomicsubtypeincludingaorticatresia/mitralatresiaand
possiblyaorticatresia/mitralstenosis,althoughlargersingle-centerand
multicenterinvestigationshavefailedtolinkanatomicsubtypetointerstage
mortalityotherthananindependentassociationbetweenaorticatresia/mitral
atresiaasnotedinthePediatricHeartNetworkSingleVentricleReconstruction
trial.17–23Potentiallymodifiablecardiacriskfactorslinkedtointerstage
mortalityincludethepresenceofarestrictiveatrialcommunication,neoaortic
archobstruction,obstructionofthesystemictopulmonaryarteryshunt,
pulmonaryarterydistortion,atrioventricularvalveinsufficiency,andthe
presenceofarrhythmias.20,23–28InterstagemortalityforpatientsinthePediatric
HeartNetworkSingleVentricleReconstructiontrialwassignificantlyhigherin
thosepatientspalliatedwithamodifiedBlalock-Taussig-Thomasshunt
comparedwiththerightventricletopulmonaryartery(Sano)conduit(18vs.6%,
P<.001)(Fig.72.1).21Noncardiacriskfactorsassociatedwithinterstage
mortalityincludecommonlyacquiredgastrointestinallosses,respiratory
illnesses,and/orfeedingdifficulties.1,27Anyofthementionedprocessesmay
influencesystemicvascularresistance,potentiallyleadtoprogressivehypoxia
and/orshock(hypovolemiaorcardiogenic),and,inthepresenceoflimited
myocardialreserveinherenttoshunt-dependentdual-distributioncirculation
afterstageIpalliation,placeinfantsatgreaterriskforseriousmorbidityand
deathregardlessoftheirapparentphysiologicreserveearlyafterinitial
palliation.


FIG.72.1 InterstagemortalityforthePediatricHeartNetworkSingle
VentricleReconstructiontrialwas12%.PalliationwithamodifiedBlalockTaussig-Thomasshuntwasassociatedwithhighermortalitywhen

comparedwiththerightventricletopulmonaryartery(Sano)conduit.
MBTS,ModifiedBlalock-Taussigshunt;RVPaS,rightventricleto
pulmonaryarteryshunt.(FromGhanayemNS,AllenKR,TabbuttS,etal.
InterstagemortalityaftertheNorwoodprocedure:resultsofthemulticenter
singleventriclereconstructiontrial.JThoracCardiovascSurg.
2012;144[4]:896–906.)

PulseOximetry
Monitoringwithinthemedicalhomeenvironmentnecessitatestechnologythatis
reliable,accessible,andeasytouse,whichledtotheselectionofpulseoximetry
astheprimaryphysiologicmonitor.Ininfantswithadual-distribution
circulation,desaturationfrombaselinemaybeindicativeoflimitedpulmonary
flowfrommyocardialdysfunction,shuntobstructionoroutgrowth,anemia,or
anacuteillnessleadingtopulmonaryvenousdesaturation.Alternatively,
saturationshigherthanbaselinemayalsobeindicativeofprogressivedisease
thatleadstoescalationinsystemicvascularresistanceandhenceincreased
pulmonarybloodflowsuchasmilddehydration.Theseclinicalscenarioshave
guidedtriageparametersforhomemonitoringofoxygensaturations(Fig.72.2).
Specifically,arterialsaturationlessthan75%orgreaterthan90%warrants
considerationforevolvingpathology.


FIG.72.2 Breachofpulseoximetry(SpO2)criteriatriagescheme.IVC,
Inferiorvenacava;LV,leftventricle;PV,pulmonaryvein;PVR,pulmonary
vascularresistance;SVC,superiorvenacava;SVR,systemicvascular
resistance.(CourtesyGilWernovsky,MD.)

Weight,Nutrition,andSomaticGrowth
Dailyassessmentofinfantweightwithadigitalscalesensitiveto10gwas
initiallyadoptedaspartoftheinterstagemonitoringprogramtoearlierdetect

milddehydrationduetoinadequateoralintake(lessthan100mL/kgperday)or
excessivegastrointestinallosses.Consensus-drivencriteriaforassessmentbya
healthcareproviderwassetatweightlossof30gorfailuretogain20gof
weightover3days.1Interestingly,breachofweightcriteriawaslesscommonly
duetodehydrationfromgastrointestinallossesandmorecommonlyassociated
withinadequateenteralintake,withvolumeslessthan100mL/kgperdayin
nearlyhalfthepatientswhobreachedweightcriteria.3
Earlyexperiencewithinterstagemonitoringofweighttrendshighlighted
growthfailurethatwasassociatedwithfunctionallyuniventricularheart.8,9,29
Thegrowthfailurecanbeattributedtoavarietyoffactorsthatleadtoinadequate
enteralintakesuchasheartfailure,geneticorextracardiacanomalies,
gastrointestinaldysmotility,and/ormalabsorption.Althoughsomeofthe
contributingfactorsarenotmodifiable,ensuringadequatenutritioninthe
presenceofthesecomorbiditiesisanessentialfunctionofinterstagemonitoring
andimportantformorehealthmaintenanceandoutcomesatstageIIpalliation,
thesuperiorcavopulmonaryconnection.Multiplestudieshaveshownthatpoor