Andersons pediatric cardiology 2296
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electivesurgerybedelayedfor6to8weeksinpatientswithanactiveURI;
however,theseverityofsymptomsandpotentialrisksofpostponingthe
procedureneedtobeconsidered.
Physicalexaminationshouldincludeadetailedevaluationoftheairway,chest,
andheart.Vitalsignassessmentshouldincludefourextremitynoninvasiveblood
pressuremeasurementstoidentifyanydiscrepancyincirculation,suchaswith
coarctationoftheaorta,aberrantsubclavianartery,orimpactofsurgicalshunts.
Determiningthepatient'sbaselineoxygensaturationandrangewillallow
tailoringperiproceduralcare.Criticalreviewoflaboratorydata,preoperative
imagingstudies,andelectrocardiogramcompleteathoroughpreoperative
cardiacanesthesiaassessment.
Currentpracticeguidelinesforpreoperativefastinghavebeendevelopedby
theAmericanSocietyofAnesthesiologistsTaskForceonPreoperativeFasting
andtheUseofPharmacologicAgentstoReducetheRiskofPulmonary
Aspiration.7Theseguidelinesallowclearliquidstobeingestedforupto2hours
beforeproceduresrequiringgeneralanesthesia,regionalanesthesia,or
proceduralsedationandanalgesia.Fastingperiodsof4hoursorlongerforbreast
milk,6hoursorlongerforinfantformula,and6hoursorlongerforlightmeals
ornonhumanmilkarerecommended.Additionalfastingtimesof8hoursor
longerwillbeneededforintakeoffriedorfattyfoodsandlargevolumesof
nonhumanmilk.Infantsonprostaglandininfusionshavedelayedgastric
emptyingtimesandlongerfastingtimesmaybewarranted.Itisimportantto
notethatencouragingparentstoadministerclearfluidsupuntil2hoursbefore
theprocedurenotonlyimprovespatientandparentalsatisfaction,butmayalso
reducetheriskofperianesthetichypotensionandpotentialshuntthrombosis.
Ideally,high-riskpatients,especiallyshuntedsingleventriclepatientsand
patientswithleftventricularoutflowtractobstruction,shouldbeanesthetized
earlyinthedaytominimizefastingtime.Thiswillalsoallowforlonger
postanestheticobservationalperiodinoutpatients.
Twofinalcircumstancesshouldbeconsideredaspartofthepreoperative
evaluation.First,manychildrenwithcongenitalcardiacdiseasemaysufferfrom
adrenalinsufficiency,whetherpartoftheirdiseaseprocessorsecondaryto
prolongedsteroidtherapy.Itisimportanttoreviewtheirendocrinologist's
recommendationspriortotheirprocedure.Finally,the2017Preventionof
InfectiveEndocarditisGuidelinesfromtheAmericanHeartAssociation8should
befamiliartoandfollowedbytheprovidercaringforthepatientwithcongenital
cardiacdiseaseundergoingsurgicalandinterventionalprocedures.
PreparationandPreproceduralSedation
Oneoftheimportantcomponentsofananesthetic,particularlyinthepediatric
cardiacpatient,isthepsychologicpreparationofthepatientandfamilyto
facilitateasmoothanestheticinduction.Athoroughpreoperativediscussion,
allayinganxietyrelatedtopriorexperiences,andpharmacologicpremedication
arehelpfulineasingthechild'sseparationfromthefamilyandfacilitating
hemodynamicandrespiratorystabilityduringinductionofgeneralanesthesiaor
sedation.Olderchildrenandteenagersmayhavedevelopedstrongpersonal
preferencesregardingpremedicationandthemethodofinductionofanesthesia
thatshouldberespected,iffeasible.Someoftheagentscurrentlyutilizedfor
pharmacologicpreparationincludemidazolam(0.5to1mg/kgbymouth[PO]or
intranasally[IN],ketamine[5to10mg/kgIN],dexmedetomidine[1to3µg/kg
IN],orpentobarbital[4to5mg/kgPO]).9–15However,pharmaceuticalsneedto
beusedcarefully,astheycancausemyocardialdepression,especiallyinthe
failingheart,16,17andmaycausehypoventilationwhichcanresultinhypercarbia,
acidosis,hypoxemia,andincreasedpulmonaryvascularresistance.2
Furthermore,patientswhoarepronetoairwayobstruction(obstructivesleep
apneaortrisomy21)maydevelopairwaycompromiseoncesedated.Inchildren
deemedinappropriateforaninhalationalinductionandthereforerequiring
intravenous(IV)accesspriortoinduction,excellentanxiolysiscanbeachieved
bytitratingmidazolamintravenouslytopatientcomfortpriortoparental
separationandentryintotheprocedureroom.
AnestheticManagement
Thegoalsoftheinductionofanesthesiaaretoproduceunconsciousnesswhile
maintainingcardiopulmonaryhomeostasis,whichcanbechallenginginpatients
withcongenitaloracquiredcardiacdisease.Carefulconsiderationofthe
cardiovasculareffectsofthedrugsandthepatient'spathophysiologyanddesired
hemodynamicgoalsallowthepediatriccardiacanesthesiologisttodeviseasafe
andeffectiveanestheticplantailoredtoeachpatient.WhilehistoricallyIV
inductionofanesthesiahadbeenrequiredinthispatientpopulation,inhalational
inductionofanesthesiaisnowfrequentlyconsideredwithoutpriorestablishing
IVaccess.Inhalationalinductionofanesthesiabymaskwithsevoflurane,nitrous
oxide,andoxygencanbeaccomplishedsafelyinthemajorityofinfantsand
childrenwhencardiacandpulmonaryfunctionsarepreserved.However,
inhalationalinductiondoestakelongerthanIVinductionandcanresultin
airwayobstructionduetorelaxationoforopharyngealmuscletone,
laryngospasm,hypoventilation,apnea,hypoxemia,bradycardia,and
hypotension.Carefulattentiontoanestheticdepth,adequacyofairwaypatency,
andhemodynamicstatuscanpreventsuchadverseeffects.Intracardiacshunting
mayaffectthespeedofinduction;inpatientswithcardiaclesionsproducing
right-to-leftshunts,maskinductionmaybeprolongedastheanestheticgas
tensioninarterialbloodrisesmoreslowly,whileIVinductioncanbeslightly
accelerated.Inpatientswithlargeleft-to-rightshunts,amorerapidinhalational
inductionmayoccurastransferoftheanestheticfromthelungsintothearterial
bloodisincreased;however,thisisvariablydemonstrated.18,19
Allvolatileanesthetics,tovaryingdegreesandbyvaryingmechanisms,can
causedirectmyocardialdepressanteffects.Ingeneral,thedifferencesamongthe
agentsoccurprimarilyfromdifferingeffectsoncalciumfluxthroughL-type
Ca2+channels,bothtranssarcolemmalandinthesarcoplasmicreticulum,
alteringthelevelofintracellularcalciumavailabletobindtothetroponin-actinmyosincomplex.Importantly,duetotheimmaturityoftheircalciumreleaseand
reuptakesystem,20infantsfrombirthtoapproximately6monthscanexhibitan
exaggerateddegreeofdepressionofmyocardialcontractilityandbloodpressure
inresponsetovolatileagents.21,22Volatileanestheticsalsodifferentiallyaffect
systemicvascularresistance,resultingindose-dependentdecreasesinarterial
pressure.
