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A comprehensive study guide for the cefm exam, covering key concepts and providing answers to frequently asked questions. It delves into various aspects of fetal heart rate monitoring, including the different modalities, their advantages and disadvantages, troubleshooting techniques, and the influence of maternal and fetal factors on fhr patterns. The guide also explores the mechanisms of exchange between fetal and maternal blood in the placenta and the role of umbilical circulation and amniotic fluid in fetal well-being.
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DescribeiFetaliHeartiRateiMonitoringi-iCorrectiAnswer- EFMimayibeiexternal,iinternalioriaicombination InitheiUS,itheimajorityiofiwomenihaveiEFMiduringisomeiorialliofitheirilab ors Eachimodalityihasibothiprosiandicons DescribeiDoppleriUltrasoundi-iCorrectiAnswer- TheidoppleriUSitransduceriisiuseditoiassessiFHRicharacteristicsiandipatt erns.iTheitransduceritranslatesisoundiwaveireflectionsiintoiwaveformsi whichiareiinterpretedibyiaicomputerianditheniexportediasianiaudibleiso undiandiaiwaveformipattern. Problems:iFHRiartifact,idoubling,ihalving,iandidetectioniofimaternalihea rtirate CurrentiultrasoundiFHRisignaliprocessingiusesiautocorrelationitechniqu esiandiinterpretationiofiEFMidataiisibasedionithisiassumption Describeiinternalifetalielectrodei-iCorrectiAnswer- TheiFSEidirectlyimeasuresitheiFHRibyimeasuringiRitoiRiwavesiinisuccessi
veiQRSicomplexes.iToiplaceianiFSE,iadequateicervicalidilationi(usuallyiati leasti 2 icm)iandiROMiareineeded. Contraindications:iplacentaiprevia,ihemophilia,imaternaliHIV,iherpesiin fections,ioriwhenipresentingipartiisinotiidentifiable Problems:iartifact,islightiriskiofifetaliinfection/injury,idoublingiorihalvin giofitheiFHR,iandipickiupiofitheiMHRiwithifetalidemise Otherirelativeicontraindications:isyphilis,igonorrheai(notirecommende dibutimayibeiplacediifiaiclearibenefititoiaimotheriandifetusicanibeidemon stratedibyiitsiuse) Describeiexternaliuterineimonitoringi-iCorrectiAnswer- Theitocotransduceri(TOCO)iisiaipressureisensitiveibutton- likeideviceithatidetectsichangesiinitheiabdominalicontouriwhenithereiisi aiuterineicontraction.iTheispecificilocationiisideterminedibyiabdominali palpationiandiisiideallyiaismoothipartiofitheiuterusiwhereinoifetalismalli partsiareifelt.iUsuallyithisiisitheifundusioriwhateveriuterineicontractionsi areimostieasilyipalpated TheiTOCOicanibestiprovide:irelativeistrength,iapproximateiduration,ian diapproximateifrequencyioficontractionsibuticannotidetermineiactualiin tensity.iPALPATIONiISiESSENTIAL
Problems:iincludeiitsiinherentilimitations,ipossibilityiofiinvertedicontrac tionsiandiissuesiwithiobesity Describeiinternaliuterineimonitoringi-iCorrectiAnswer- IUPCiallowsiforigreateriquantitativeimeasurementiofiuterineicontractio nifrequency,iduration,iandiintensityioripeakiintrauterineipressureiandire stingitone Threeitypes:ifluid-filledi(othericountries),itransducer-tipped,iandiair- couplediorisensor-tippedi(whatiweiused) Measures:iactualipressuresiinimmHgiandimostiallowiforiamnioinfustion Indicationsiforiuse:iNeediforiamnioinfusion,ititrationiofioxytociniforiind uctionioriaugmentationiwheniexternalimethodsiareinotiprovidingienoug hiinformation,iandilackiofiprogressiinilabor Problems:iuserierror,idisplacement,iplacentaliabruption/shearing,iandi aismalliriskiofiuterineiperforation WhatiareitheithreeitypesiofiIUPCimonitors?i-iCorrectiAnswer-Fluid- filled:ialsoicalleditheiwatericolumnimethod,iwasithei1stitypeiofiIUPCiavai lableiandiuseidramaticallyidecreasediafteriintroductioniofitheitransduce r- tippedicatheter.iItiworksibyitransmittingitheipressureigeneratedibyiaico ntractionithroughiaiwatericolumnitoiaitransducerilocatediawayifromithei
sourceiofipressure,itypicallyiatitheimonitorisite.iThisidisplacedifluidiexer tsipressureiagainstiaidiaphragmiinitheitransducer,igeneratingichangesiini theielectricaliresistanceiofiaiseriesiofiwires.iTheseielectricalichangesiarei converteditoimeasuresiofipressure. Transducer-tipped:iIntroducediinithei1980siasianialternativeitoifluid- filled.iTheiforceiexertedibyiaiuterineicontractioniisiconverteditoianielectr icalisignalithatiisitransmittedithroughiaiwireisystemitoiaifetalimonitoriwh ereitheiuterineiactivityiisidisplayedigraphicallyionitheifetalimonitoritraci ng Sensor-tipped:iAir- couplingitechnology,iwhichiisiainewerimethodiofiIUPCimonitoring,iusesi aidistallyimountediflexibleiballooniinitheiuterusiconnecteditoianiexterna lireusableitransduceriinitheimonitoricable.iSimilaritoinoninvasiveibloodi pressureimonitors,ithisicathetericonsistsiofiaimembraneisensoriatitheiti piofitheicatheterithaticommuniatedipressuresithroughiaimicrocolumniof iairitoiaitransducerilocatedioutsideitheibody WhatiisitheipaperispeediforiEFMitracing?i-iCorrectiAnswer- Changesiinipaperispeedicanisubstantiallyialteritheiappearanceiofitheitra cing.iTheicommonlyiusedipaperiinitheiUSihasimarkingsionitheiverticalisca leifromi 30 - 240 ibpmiwithidividingilinesiati 10 - bpmiintervals.iShouldibeisetitoi3cmionitheihorizontaliscalei(slowerithani Europe)
Whatiisiartifact?i-iCorrectiAnswer- IrregularivariationsioriabsenceiofitheiFHRionitheifetalimonitorirecordires ultingifromimechanicalilimitationsiofitheimonitor,ielectricaliinterferenc e,ioriweakisignal,iappearingiasigapsioridots.iWithiFSE,iartifactimayiappea riinitheiformiofiirregularilinesiwithivaryingilengths.i FSEiartifactivsiarrhythmias:iarrhythmiasiwillibeiregularilines Whatiisihalf-countingiiniregardsitoitheiFHR?i-iCorrectiAnswer- MosticommonlyiseeniwhenitheiFHRiisirapid,isuchiasiwithifetalisupravent ricularitachycardia Whatiisidouble-countingiiniregardsitoiFHR?i-iCorrectiAnswer- Mayioccuriduringiperiodsiofibradycardia Whatiareisomeitroubleshootingiinterventionsiforifetalimonitoring?i- iCorrectiAnswer- RepositioningitheiUSitransducer,iensuringianiadequateiamountioficoupl ingigeliisiused,iandicheckingiforiproperiplacementiofiFSE Checkimaternalipulse,iencourageimaternalipositionichanges,itightenibel tiasineeded,icheckiconnectionitoitheipowerisourceiasiwelliasiconnection sitoitheimonitor,iapplyiFSEiificlinicallyiindicated Whatiareisomeipatientieducationipointsiforifetalimonitoring?i- iCorrectiAnswer-
Educationiregardingiavailableiandirecommendedimethodsiofifetaliasses smentishouldibeicustomizediforieachiwomaniandiisiessentialiforiwomeni toimakeifullyiinformedidecisionsiaboutitheirihealthicare.iExplainihowieq uipmentiworks.iUseiintermittentiauscultationiwheniable WhatiareisomeiextrinsiciinfluencesioniFHRipatterns?i-iCorrectiAnswer- Maternaliinfluences Uteroplacentaliperfusion Umbilicalicirculation Amnioticifluidicharacteristics WhatiareimaternaliinfluencesioniFHRipatterns?i-iCorrectiAnswer- Oxygenationistatus,ihemoglobinilevelsi(abilityitoicarryioxygenionieachi molecule),ianythingithatiaffectsiuterineibloodiflowi(smokers,ihypertens ion,ihypotension),imaternalicardiacioutput- iwilliinfluenceiuterineibloodiflow WhatiareiuteroplacentalicirculationifactorsithatiinfluenceiFHRipatterns? i-iCorrectiAnswer- UterineibloodiflowiisidependentionimaternaliBP.iFactorsiaffectingiuterin eibloodiflowiinclude:icontractions,ihypertonus,ihypertension,ihypotensi on,ivasocontstriction. Maternalibloodientersitheiintervillousispaceiinitheiplacentaiviaispiraliart eries...itheiexchangeiofigasesiandinutrientsioccuriatitheichorionicivilli.
Placentalitransfericanibeiaffectediby:iPlacentaliareai(IUGR,iabruption),ic oncentrationigradients,idiffusingidistance,iuterineibloodiflow,iumbilicali bloodiflow Whatiareitheimechanismsiofiexchangeibetweenifetaliandimaternalibloo diinitheiplacenta?i-iCorrectiAnswer- Simpleidiffusion:ioxygen,icarbonidioxide,imanyidrugs Facilitatedidiffusion:iglucose,icarbs Activeitransport:ilargeiions,iwater-solubleivitamins,iaminoiacids Bulkiflow:iwater,idissolvedielectrolytes Pinocytosis:iimmuneiglobulins,iserumiproteins Breaksiandileakage:imaternaliorifetalibloodicells WhatiareiplacentalichangesithatiaffectiFHR?i-iCorrectiAnswer- Oldiplacentaiwithilesions/calcificationsimayinotiperfuseiasiwell.iVasoco nstrictionifromiHTNicanidecreaseibloodiflowitoitheiuterusiandiplacenta.i Abruption.iPostmaturityi(agingiplacenta).iIfiplacentaifunctioniisidecreas ed,itheifetusimayirunioutiofifetalireservesiveryiquickly.i 70 - 90%iofimaternalibloodiperfusingitheiuterusipassesithroughitheiintervillo usispace HowicaniumbilicalicirculationiaffectiFHR?i-iCorrectiAnswer- Canibeiaffectedibyianiabnormalicord,icordicompressionisuchiasinuchalior itrueiknot,ioneiarteryiinsteadiofitwoi(twoivesselicord)
HowicaniamnioticifluidiaffectiFHR?i-iCorrectiAnswer- Amnioticifluididecreasesiasitheipregnancyinearsitermiandipostiterm.iAm nioticifluidicushionsitheifetusiandicordifromicontractions.iIfivolumeiiside creasing,iitifanialsoiindirectlyiindicateiworseningiplacentalifunction...iasi bloodiisishuntediawayifromikidneys,iwhichidecreasesifetalioutput.i Polyhydramnios:i60%iidiopathic,ibuticanibeiassociatediwithimultipleiges tation,idiabetes,ihydrops,ichromosomalidisorders Oligohydramnios:i(EFIi<5cm)iassociatediwithiIUGR,irenalianomalies,ipul monaryihypoplasia,ipost-termipregnancyiandiROM WhatiareisomeiintrinsicifactorsithatiinfluenceiFHRipatterns?i- iCorrectiAnswer- Fetalicirculation,icardioregulatoryicenter,iautomonicinervousisystemire sponsesi(parasympathetic,isympathetic),ibaroreceptors,ichemorecepto rs,ihormonaliresponses HowidoesifetalicirculationiinfluenceiFHR?i-iCorrectiAnswer- Oppositeiinifetus:i 1 iveinicarryioxygenatedibloodiTOitheifetus,i 2 iarteriesic arryioxygenipooriandiwasteiproductsiBACKitoitheiplacenta. Rememberitheipneumonic:iAVA Oxygenigoesitoitheimostivitaliorgansi1st:iHeartiandibrain.
Ifithereiareifetalicompensatoryimechanismsioccuringidtitheisuboptimalii ntrauterineienvironment,ithisiisiwhereiyouimightiseeiIUGRiasitheibloodif lowiisishuntingiawayifromilessivitaliorgans. Oxygenationioccursiinitheiplacenta,inotitheilungs Theseishuntsiallowipreferentialistreamingitoitheivitaliorgansiandireturn sideoxygenatediblooditoitheiplacentaitoibeireoxygeneatedi(Thereiisilessi bloodiflowitoitheilungsiasiitiisinotiessentialiatithisitime) HowidoesitheicardioregulatoryicenteriaffectiFHR?i-iCorrectiAnswer- Locatediinitheimedullaioblongata. Interactsiwithitheiotherisystemsi(sympathetic,iparasympathetic,ibarore ceptors)iandiintegratesiitiallitoicontroliFHRibaselineirate,ivariability HowidoesitheiparasympatheticinervousisystemiaffectiFHR?i- iCorrectiAnswer-Stimulationiofitheivagusinerve. ThinkiSLOW,ivagaliresponse DecreasesitheiFHR SlowsitheiSAinodei(intrinsicipacemaker)iwithiadvancingigestationaliage,i resultingiiniloweriFHRibaselineiandiincreasediFHRivariability. ParasympatheticimayihaveiailargeriroleiiniFHRivariability Mayibeicausedibyifetaliheadicompressioni-
iearlyidecel,iCPD,ifetalidescent,iSVE,irepeatediscalpistimulation
HowidoesitheisympatheticinervousisystemiaffectiFHR?i-iCorrectiAnswer- Locatedithroughoutitheimyometrium. IncreasesiFHR Causesiperipheralivasoconstrictioni->iincreasesiFHR Inistress,iwillimoveiblooditowardsiessentialiorgansiandishuntiawayifromi lessivitaliorgans Stimulationireleasesicatecholaminesi(norepinephrine,iepinephrine)i-
iincreasesibloodiflowitoivitaliorgansi(brain,iheart,iadrenaliglands) HowidoibaroreceptorsiaffectiFHR?i-iCorrectiAnswer-Stretchireceptors SensitiveitoipressureichangesiinifetaliBP WhenifetaliBPiincreases,ianiimpulseiisisentitoivagusinerveicausingianiabr uptidecreaseiiniFHR,icardiacioutputiandibloodipressureiresultingiinivaria bleidecelionifetalimonitor Bothibaroreceptorsiandichemoreceptorsiareilocatediinitheiaorticiarchia ndicarotidisinuses HowidoichemoreceptorsiaffectiFHR?i-iCorrectiAnswer- Notiasiwelliunderstood SensitiveitoichangesiiniincreasediPCO2ioridecreasediPO2. CombinedieffectiofislowingitheiFHRi(lateiorivariableidecel) HowidoihormonaliresponsesiaffectiFHR?i-iCorrectiAnswer- Regulatesicirculationiandidistributionitoivitaliorgans.
ParasympatheticireleasesiacetylcholineiwhichislowsiFHR.i Sympatheticiresponseireleasesiepinephrineiandinorepinephrine,iresulti ngiiniperipheralivasoconstriction,ishuntingiofiblooditoiheart,ibrain,iadre naliglands.iIncreasesiFHR,icardiacioutput,iarterialiBP.i Arginineivasopressinifromipituitary- ivasoconstrictioniandishunting.iThinkioligohydramniosiasiaimarkeriforife talicompromise Describeifetalireservei-iCorrectiAnswer- Normalifetalireserve:ifetusihasiexcessiresourceitoitolerateitheinormalistr essesiofilaboriandihypoxemiaiiticanitolerateibeforeiprogressingitoitissuei hyposia 1.iHomeostaticicompensatoryiresponses:ialliofitheiintrinsiciinfluencesial lowitheifetusitoiredistributeibloodiflowitoitheivitaliorgansiwhenineededi (fetalicirculation,iCRC,iANS<ibaroreceptors,ichemoreceptors,ihormonali responses) 2.iPlacentalitransfericapacity:iifitheifetusiandiplacentaiareinormal,ithenit heiplacentalitransfericapacityiisitwiceitheiamountiofiresourcesineeded- iextrensici(maternaliinfluences,iuteroplacentaliperfusion,iumbilicalicirc ulation,iamnioticifluidicharacteristics) Asitheiplacentalifunctionidecreases,i<75%iwilliresultiinievolvingiIUGRiasi theigasiandinutrientiexchangeidecreases
Describeiuterineiactivityi-iCorrectiAnswer-Normal:ictxsieveryi 2 - 5 imin,ilastingi 30 - 90 iseconds Palpation:imild,imoderate,istrong IUPC:ipeakimmHg,ibaseline,iduration NICHD:inormaliequaliorilessithani 5 ictxsiiniai 10 iminuteiperiod,iaverageiov eri 30 iminutes Document:iduration,iintensityiandirestingiwhetheriIUPCioritoco Describeitachysystolei-iCorrectiAnswer- Greaterithani 5 ictxsiini 10 iminutesiaveragedioveri 30 iminutes Doinotiuseihyperstimulationiorihypercontractility Importantitoidecreaseiuterineiactivity,ieveniifitracingishowsiwellioxygen atedifetus Describeihypertonusi-iCorrectiAnswer-Normal:irestingitonei 5 - 20 immHg Hypertonus:irestingitoneigreaterithani 20 - 25 immHg,isomeiinstitutionsiwillidefineiasianiincreaseioveribaseline.iAlso ,ibyipalpation,iabdomeniisinotisoftibetweenictxs Whatiareisomeifactorsithatiaffectifetalioxygenation?i-iCorrectiAnswer- Uterineiactivity Maternalifactors Hormones Anesthesia
Drugsi(therapeuticiandirecreational) Placentalifactors Umbilicalibloodiflow Acid-baseibalance Howidoesiuterineiactivity/ibloodiflowiaffectifetalioxygenation?i- iCorrectiAnswer-Uterineicontractionsidecreaseiuterineibloodiflow. Stasisiinitheiintervillousispaceiduringictxs,isoifetusireliesioniitsireserves. Wontihaveimuchireserveiifiplacentalifunctioniisidecreased. Hypertonusioritachysystole. Hypotension Hypertension Vasoconstriction Whatiareimaternalifactorsithatiaffectifetalioxygenation?i- iCorrectiAnswer-Anythingithatiaffectsiuterineibloodiflow Preeclampsiaiorihypertension Diabetes Obesity/inutrition Cardiovasculariconditions Asthma Anemia ABOiincompatibilities
Smokers Howidoesianesthesiaiaffectifetalioxygenation?i-iCorrectiAnswer- Hypotensioniresultingifromivasodilationi-
idecreasedibloodiflowitoitheiplacentai->ibaby Accidentaliintrathecalicatheteriplacementiresultingiinimoreiprofoundim aternalieffectsi->iaffectibaby Howidoitherapeuticiandirecreationalidrugsiaffectifetalioxygenation?i- iCorrectiAnswer- Aithoroughihistoryiofianyiprescription,iherbal,ioveritheicounter,iandiillici tidrugsiisiimportantiasiitimayihaveianieffectionifetalioxygenationiandiFH Ritracing Whatiareisomeiplacentalifactorsithatiaffectifetalioxygenation?i- iCorrectiAnswer-Surfaceiarea Placentalitransfericapacity Age Describeiacid-baseistatusiiniuteroi-iCorrectiAnswer-Iniainormal,iwell- oxygenatedifetus,iaerobicimetabolismiisiuseditoiproduceienergy;idepen dingionioxygen. Ifioxygeniisntiavailable,ifetusiusesianaerobicimetabolismi- iconvertsiglucoseiandiglycogenistoresiforienergy.
Anareobiciproducesimuchilessienergyithaniaerobiciandiwillionlyicoverib asalimetabolicineedsi(heart,ilungs,iadrenaliglands).iAlsoiaccumulatesilac ticiacidiasiaiwasteiproduct. Respiratoryiacidemia:iFromitheiexcessiofibyproductsiCO2iandiH2Oiaccu mulatingiintoihydrogeniandibicarbiions.ipHidrops.iNotiassociatediwithip oorioutcomes,inotifromilackiofioxygen Metaboliciacidemia:iLacticiacidiby- productihasitoibeibuffered;iacidemiaioccursiifitheifetusihasiusediupiitsibu fferingicapability.i>12ibaseiexcess/baseideficit Whatiareitheinormalicordigasivalues?i-iCorrectiAnswer-pHi_>i7. PO2i_>i 20 PCO2i< HCO3i(bicarb)i> Baseideficiti< Whatiareimetaboliciacidosisicordigasivalues?i-iCorrectiAnswer-Normal: pHi_>i7. PO2i_>i 20 PCO2i< HCO3i(bicarb)i> Baseideficiti<
Whatiareitheimixedicordigasivalues?i-iCorrectiAnswer-pHi_>i7. PO2i_>i 20 PCO2i< HCO3i(bicarb)i> Baseideficiti< pHi<7. PO2i< PCO2i> HCO3i(bicarb)i< Baseideficiti_>i 12 WhatiareisomeiNICHDiassumptions?i-iCorrectiAnswer- Developediforivisualiinterpretation Intrapartumiemphasis Noiassumptionsiregardingietiologyioripathophysiology Patternicategories: Baselinei(includesirateiandivariability) Periodici(relateditoicontractions) Episodici(unrelateditoicontractions)
Shortitermivariabilityiandilongitermivariabilityinoilongeriused MustievaluateiEFMiinicontext DirectielectrodeioriexternaliDoppler-ipaperispeedi3cm/minute DescribeihowiaiFHRitracingiisievaluatedi-iCorrectiAnswer- AifullidescriptioniofiEFMitracingirequiresiaiqualitativeiandiquantitativeid escroptioniofithese: Baselineirate Baselineivariability Presenceiofiperiodicioriepisodicidecelerationsioriaccelerations Uterineiactivity Changesioritrendsioveritime Describeibaselineifetaliheartiratei-iCorrectiAnswer- ApproximateimeaniFHRiroundeditoiincrementsiofi 5 ibeatsiperiminute Readioveriai 10 iminuteiwindowi(needi 2 iminutesiminimumibutinoticontig uous) Excludesiaccelerations,idecelerations,imarkedivariability Bradycardia:ibaselinei<110ibpm Tachycardia:ibaselinei<160ibpm Thereimustibeiatileasti 2 iminutesiofiidentifiableibaselineisegmentsi(notin ecessarilyicontiguous)iinianyi 10 iminuteiwindow,ioritheibaselineiforithati periodiisiindeterminate
Inisuchicases,iitimayibeinecessaryitoireferitoitheipreviousi 10 iminuteiwind owiforideterminationiofitheibaseline AbnormalibaselineiisitermedibradycardiaiwhenitheibaselineiFHRiisi<110i bpm;iitiisitermeditachycardiaiwhenitheibaselineiFHRiisi>160ibpm WhatiregulatesiFHRibaseline?i(physiology)i-iCorrectiAnswer- Intrinsicicardiacipacemakersi(SAinode,iAVinode)iandiconductionipathwa ys Autonomiciinnervationi(sympathetic,iparasympathetic) Humoralifactorsi(catecholamines- iregulatedibyitheisympatheticisystemitoispeedithingsiup) Extrinsicifactorsi(medications) Localifactorsi(calcium,ipotassium) AutonomiciinputiregulatesiFHRiiniresponseitoifluctuationsiiniPO2,iPCO2i andibloodipressureidetectedibyichemoreceptorsiandibaroreceptorsiloca tediinitheiaorticiarchiandicarotidiarteries WhatiincreasesiFHRibaseline?i(physiology)i-iCorrectiAnswer- Sympatheticiinnervationiandiplasmaicatecholamines WhatidecreasesiFHRibaseline?i(physiology)i-iCorrectiAnswer- Parasympatheticiinnervation
Whatiareiconditionsipotentiallyiassociatediwithifetalitachycardia?i- iCorrectiAnswer-Maternalifever Infection Medications/drugs Sympathomimetrics Parasympatholytics Caffeine Theophylline Cocaine,imethamphetamine Fetalianemia Maternalihyperthyroidism Arrhythmia Sinusitachycarida Supraventricularitachycardia Atrialifibrillation Atrialiflutter Ventriculariarrhythmia Metaboliciacidemia Hypoxemia Maternalifever Drugs Maternalithyroididisease
Fetalianemia/ifetaliheartifailure Amnionitis Fetaliarrhythmia Whaticonditionsiareipotentiallyiassociatediwithifetalibradycardia?i- iCorrectiAnswer-Medications Sympatholytics Cardiaciconductioniabnormalities Heartiblock Heterotaxyisyndrome Structuralicardiacidefects Viraliinfections Sjogrensiantibodies Fetaliheartifailure Maternalihypoglycemia Maternalihypothermia Interruptioniofifetalioxygenation Hypoxemia Reflexi(pureivagaliresponse) Drugs Maternalihypothermia Fetaliarrhythmia
DescribeibaselineiFHRivariabilityi-iCorrectiAnswer- FluctuationsiinitheibaselineiFHRithatiareiirregulariiniamplitudeiandifrequ ency Fluctuationsiareivisuallyiquantitatediasitheiamplitudeiofipeak-to- troughiinibpm Determinediiniai 10 - minuteiwindow Excludesiaccelerationsiandidecelerations Variabilityiclassifications: Absent:iUndetectable Minimal:i>undetectableibuti_<5ibpm Moderate:i 6 - 25 ibpm Marked:i>25ibpm DescribeitheibaselineiFHRivariabilityiphysiologyi-iCorrectiAnswer- FactorsithatiregulateiFHRivariability: Cardiacipacemakersi(SAinode,iAVinode) Cardiaciconductionisystem Autonomiciinnervationi(sympathetic,iparasympathetic) Humoralifactorsi(catecholemines) Extrinsticifactorsi(medications) Localifactorsi(Calcium,ipotassium)
FluctuationsiiniPO2,iPCO2,iandibloodipressure FluctuationsiiniPO2,iPCO2iandiBPiareidetectedibyichemoreceptorsiandib aroreceptorsilocatediinitheiaorticiarchiandicarotidiarteries Signalsifromitheseireceptorsiareiprocessediinitheimedullaryivasomotoric enter,ipossiblyiwithiregulatoryiinputifromihighericentersiinitheihypothal amusiandicerebralicortex. Sympatheticiandiparasympatheticisignalsifromitheimedullaryivasomoto ricenterimodulateitheiFHRiiniresponseitoimoment-to- momentichangesiinifetaliPO2,iPCO2,iandiBP. Withieveryiheartibeat,islighticorrectionsiinitheiheartirateihelpitoioptimiz eifetalicardiacioutputiandimaximizeitheidistributioniofioxygenatedibloo ditoitheifetalitissues.iTheivariationiisireferreditoiasiFHRivariabilityiandiisi displayedivisuallyionitheiFHRigraphiasianiirregularihorizontaliline Whatiareiconditionsipotentiallyiassociatediwithiminimal- absentiFHRivariabilityianditheiabsenceiofiaccelerations?i- iCorrectiAnswer-Fetalisleepyicycle Fetalitachycardia Medications Narcotics Barbiturates Phenothiazines Tranquilizers Generalianesthetics
Atropine Prematurity Congenitalianomalies Fetalianemia Fetalicardiaciarrhythmia Infection Preexistingineurologiciinjury Fetalimetaboliciacidosis Differentials: Hypoxemia/hypoxia Fetalisleepicycle Drugs Congenitalianomalies Fetaliprematurity Fetalitachycardia Describeimarkedivariabilityi-iCorrectiAnswer- Significanceiofimarkedivariabilityinotiknown.iPossibleiexplanationsiincl udeiainormalivariantiorianiexaggeratediautonomiciresponseitoiinterrupt ioniofifetalioxygenation.
Itiisipresumeditoiresultifromianiincreaseiinialpha- adrenergiciactivity,iwhichicausesiselectiveivasoconstrictionioficertainiva scularibeds. Someistudiesihaveiassociatedimarkedivariabilityiwithiprolongedipregna ncies,imaternaliephedrineiadministration,ifetalibreathing,iandidecrease diuteroplacentaliperfusionioriumbilicalicordicompression. Interventions:iPromoteiplacentalibloodiflowiandifetalioxygenationi(late ralipositioning,icorrectingimaternalihypotensionioriexcessiveiuterineiact ivity,ifluidibolus,iorioxygen) Differentials:iFetaliactivity,ifetalistimulation,ihypoxemia/hypoxiaidueit oicordiprolapse/icompression,imaternalihypotension,iuterineitachysyst ole,iabruptioiplacenta DescribeisinusoidaliFHRipatterni-iCorrectiAnswer- Smoothiandiregularisineiwave-likeipattern.iNotiaitypeiofivariability.i 3 - 5 icyclesiperiminute.iMustibeipresentifori 20 iminutesitoidiagnose.iPathop hysiologicimechanisminotiknown,ibuticlassicallyithisipatterniisiassociate diwithisevereifetalianemia.iVariationsiofithisipatternihaveibeenidescribe diiniassociationiwithichorioamnionitis,ifetalisepsis,ioriadministrationiofi narcoticianalgesics. Etiology:iSevereifetalianemiaiasiairesultiofiRhiisoimmunization,imassivei feto-maternalihemorrhage,itwin-to- twinitransfusionisyndrome,iruptureivasaiprevia,iandifetaliintracranialih emorrhage