Andersons pediatric cardiology 1865
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (100.44 KB, 3 trang )
ElevatedTPG
CVP:low
Atrialpressure:low
3.Elevatedpulmonaryvascularresistance
4.Pulmonaryvenousobstruction
Hypovolemia
CVP,Centralvenouspressure,measuredintheFontanbaffle,superiorcavalvein,orpulmonary
artery;TPG,transpulmonarygradient.
Thenecessarymanagementstrategiestotreatlowcardiacoutputdependon
theirfundamentalcausesandmayrangefromvolumeresuscitation,chest
drainage,antiarrhythmicmedications,pulmonaryvasodilators,vasoactive
support,catheterinterventions,andsoforth.Broadrecommendationsare
thereforenothelpfulinthescenariooflowcardiacoutputinthispopulation.The
keytoappropriatemanagementisidentificationofthecause.Itisimportantfor
themanagementteamtofirstandforemosthaveknowledgeofthepreoperative
statusofthepatient,includingpulmonaryarterysizeandpressure,PVR,
ventricularend-diastolicpressure,ventricularandAVvalvefunction,andso
forth.Next,theteamprovidingpostoperativecaremusthaveacomplete
understandingoftheprocedureandcourseintheoperatingroom.Themost
importantdataduringtheearlypostoperativeperiodisthatobtainedfrom
intravascularcathetersinthecentralvenouscompartmentandthecommon
atrium,comparingthosevaluestothepreoperativeandintraoperativevalues.An
echocardiogramwillfurtherassessventricularfunctionaswellanAVvalve
regurgitationandevaluateforextracardiacfluid.Postoperativeacousticaccess
maybequitelimited,andcardiaccatheterizationmaybenecessarytoconfirm
hemodynamicfindingsandevaluatethesurgicalanastomosesandpulmonary
arterialtree.Managementstrategiesarethentailoredtothespecificanatomy,
physiologyandcauseoflowcardiacoutput.Inrefractorycases,theFontan
operationmayneedtobe“takendown”toaSCPCorsystemic-to-pulmonary
arteryshunt;thisoccursin1%to4%ofcaseswithhighearlyandlatemortality
rates.296–299
RhythmDisturbances
PostoperativerhythmdisturbancesfollowingtheFontanarecommonandoccur
inapproximately30%ofpatients.300–303Themostcommonearlyarrhythmias
aresinusnodedysfunction,junctionalectopicrhythm,andatrialtachycardias.It
isimportantforoptimizationofpostoperativehemodynamicstomaintain
atrioventricularsynchronyintheearlypostoperativeperiod.Inthecaseofa
junctionalectopictachycardia,measurestocontroltherateofaccelerated
junctionalrhythmprimarilyincludeminimizationofendogenous(painand
agitation)andexogenous(vasoactivemedications)catecholaminesand
pharmacologictherapy.Althoughwhole-bodycoolinghasbeenutilizedinother
patientpopulations,thisrequiresneuromuscularblockadetopreventshivering
andthusmechanicalventilation,whichfurthercompromiseshemodynamics.
(Counterintuitively,extubatingthepatientwithanacceleratednodalrhythmmay
actuallyimprovehemodynamicsandslowthejunctionalrate,allowingforatrial
pacingorreturnofsinusrhythm.Shouldthisapproachbetried,equipment
neededforpromptreintubationshouldbeavailable.)Pharmacologictherapies
forjunctionalectopictachycardiaincludeamiodarone,procainamide,and
dexmedetomidine.Oncetherateofthejunctionalrhythmhasbeencontrolled,
AVsynchronymaybeachievedwithtemporaryatrialpacing.Temporarypacing
maneuversmayalsobehelpfulforsinusnodedysfunction.Atrialtachycardias
maybeterminatedwithrapidatrialpacingmaneuversviatemporarypacing
wireswhenavailableorcardioversionwhenappropriate.
Effusions/Chylothorax
Chylothorax,requiringchesttubesgreaterthan1week,isacommon
complicationfollowingaFontan,occurringinupto25%.236Bothcausesand
managementaresimilartothesituationafterasuperiorcavopulmonary
anastomosis.Elevationofcentralvenouspressureisapredictableconsequence
ofpalliationforfUVHandcanimpairnormaldrainageoflymphaticfluidinto
thecentralvenoussystem,resultinginachylothorax.Asaconsequence,chylous
drainageiscommonafteraFontanandofslightlylongerdurationthanaftera
superiorcavopulmonaryanastomosis,butitgenerallyresolvesin4to5days.
Thefirststepinthemanagementofchylothoraxistoruleoutanyanatomic
abnormalitiesthatcouldraisecentralvenouspressure,suchasobstructionofthe
Fontanorsignificantaortopulmonarycollateralburden.Iftherearenoanatomic
issues,astepwisetreatmentplanisbegunthatstartswithalow-fatdiettolimit
stimulatinglymphproduction.ThiscanbeescalatedtoNPOandTPN.
Additionalmedicaltherapiescanbeadded,includingoctreotide,steroids,and
aldactone.237Unlikethesituationafterthesuperiorcavopulmonaryanastomosis
followingtheFontanprocedure,allornearlyallthecardiacoutputmusttraverse
thepulmonaryvascularbedandanyelevationofPVRwilladdarithmeticallyto
thecentralvenouspressure.Pulmonaryvasodilatorssuchasinhalednitricoxide
orsildenafilmaybeusefulinloweringthetranspulmonarygradientandthereby
thecentralvenouspressure.Pleurodesiscanbeconsidered.Again,treatment
mustalsobedirectedatthepathophysiologyofongoinglossofchylousfluid.
Patientswithprolongedeffusionsareatriskformalnutrition,infection,and
thromboticcomplications.Eliminatingoralintaketodecreaselymphproduction
combinedwithTPNshouldbeconsideredearlyasbothatreatmentofthe
chylothoraxandtoavoidongoingproteinlossandmalnutrition.Aportionofthe
chesttubeoutputshouldbereplacedwithfreshfrozenplasmatoameliorateloss
ofcoagulationfactors.
