quiz answers 15th feb 2017 · external defibrillators (aeds) and implantable cardioverter...

QUIZ15thFeb2017–answersbelowWhatisthetoppriorityinadultcardiacarrestmanagement?Whatistheroleof3-stackedshocksinALS?Whatarethebenefitsofexternalpacing?Whatarethelimitationsofexternalpacing?DescribeandinterpretthefollowingECG.

QUIZanswers15thFeb2017Whatisthetoppriorityinadultcardiacarrestmanagement?Defibrillation of a shockable rhythm is the intervention that clearly does themost toincrease a patient’s chance of survival. Hence the use of public access AutomaticExternalDefibrillators(AEDs)andImplantableCardioverterDefibrillators(ICDs).Thechanceofsuccessfuldefibrillationdecreasesexponentiallyovertimeandthereisnoevidencethataperiodofchestcompressionspriortodefibrillationisofbenefit.A shock of maximum joules should be administered immediately, with uninterruptedchestcompressionsbeingperformeduntilthatshockcanbedelivered.AustralianResuscitationCouncil(ARC)Guidelines2016Whatistheroleof3-stackedshocksinALS?ILCOR (and subsequently ARC) recommendations changed in 2010, removing therecommendationfor3-stackedshocksinwitnessedcardiacarrest.Theconcernisthat3-stackedshockscauseanunjustifiablylonginterruptiontochestcompression.Thereareexceptions.It isacknowledgedintheILCOR(InternationalLiaisonCommitteeonResuscitation)ALStaskforcedocuments2015thattheremaybecircumstanceswhere3-stacked shocks could be considered in witnessed, monitored VF with defibrillatorimmediatelyavailable.This isnotmentioned inARC,ANZCORorAHAguidelinesbut isacknowledgedintheERC(Europeanguidelines).AtStVincent’sHospital, it isaccepted thata3-stackedshockstrategymaybeused intheEPSlab,incardiothoracictheatreandinpatientswithin10daysofcardiacsurgery.Itmayalsobe considered inpatientswithdefibrillationpadsalreadyapplied (eg. STEMIawaiting cath lab) although a single shock strategy is still acceptable as per ARCguidelines.InternationalConsensusonCardiopulmonaryResuscitationandEmergencyCardiovascularCare ScienceWithTreatmentRecommendations.2015.Part4ALS.Whatarethebenefitsofexternalpacing?

• Canbequicklyappliedtopatientusingmanualdefibrillator• Easytoperform,requiringminimaltraining• Rateandcurrenteasilyadjusted• Demandorfixedpacingmodesarepossible• Longerpulsedurationinmoderndevicesreducescaptureofskeletalmuscleand

currentupto200mAcanbedeliveredtolerably• Avoids“pro-arrhythmic”and“hypotensive”sideeffectsofpharmacotherapy• Noninvasive;noriskofbleedinginthrombolysedpatients• Temporisingmeasure;eg.maynotberequiredpostPCI

Whatarethelimitationsofexternalpacing?

• Needcardiacoutput;pacingofasystoleorPEAisofnoprovenbenefit• Successfulcapturemaynotbepossible• Skeletalmusclecaptureinvariablyoccursandcancausesignificantdiscomfortto

thepatientrequiringanalgesia+/-sedation• Prolongedexternalpacingcancauseburnstotheskin;padsshouldbechanged

every4-5hours• Pacing is simultaneous atrial and ventricular, so there is no “atrial kick” of AV

sequentialpacing1.SVHALSGuidelines20172.AliASovariTranscutaneousCardiacPacingMedscapeUpdatedDec2014Accessed17thDec2017DescribeandinterpretthefollowingECG.

Sinusrhythm68/minwith1xPVC(#10)Pwaves

UprightinII,consistentwithsinusoriginBiphasicinV1whichcouldindicateleftatrialenlargement

PRinterval Slightlyprolonged~220msec=1stdegreeHBQRS Narrow Normalaxis NormalRwaveprogression NopathologicalqwavesSTsegment MarkedSTelevationinferiorlyII,III,aVFof3-4mm ElevationinIII>IIsuggestingrightcoronaryarteryasculprit SlightSTelevationinV1;suspiciousforRVinfarction MarkedSTdepressionaVLof3mm STdepressionanteroseptallyV2-5TwaveinversiondevelopinginaVLandV2-3.QTc Normal

ImpressionAcuteRCAocclusioncausinginferiorSTelevationandreciprocalSTdepressionindicatinginferiorwallinfarction.V1STelevationwithSTdepressioninV2ishighlysuggestiveofRVinfarction.

ImplicationsUrgentcoronaryinterventionisindicated.Inferiorinfarctionmeansthereis20%riskofsignificant2ndor3rddegreeheartblock.RV infarctionmeans that theheartcanbeverypreloaddependent forcardiacoutput.Fluid boluses may be required for hypotension and nitrates can cause cardiovascularcollapse.PrognosisisworsethanforinferiorAMIalone.