epidural-review课件

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1、EpiduralReviewKateHagan,M.D.10/14/2008AnatomyAteachvertebrallevel,pairedspinalnervesexitthecentralnervoussystemThe1stcervicalvertebraistheatlasThe2ndcervicalvertebraistheaxisAll12thoracicvertebraearticulatewiththeircorrespondingribThespinalcordsitsinthehollowr

2、ingbordered-anteriorlybythevertebralbody-laterallybythepediclesandtransverseprocesses-posteriorlybythelaminaandtransverseprocesses3layersofmeningesthepia,arachnoid,andduraCSFisfoundbetweenthepiaandarachnoidmembranesSpinalcordgoestoL1inadultsandL3inchildrenAtth

3、ecervicallevelnervesariseabovetheirrespectivevertebrae,butstartingatT1theyexitbelowSubduralspaceextendstoS2inadultsandS3inchildrenBloodsupplytothespinalcordandnerverootsisderivedfromasingleanteriorspinalarteryandpairedposteriorspinalarteriesAnteriorspinalarter

4、yisformedfromthevertebralartery,supplyingtheanterior2/3ofthespinalcoredPosteriorspinalarteriesarederivedfromtheposteriorinferiorcerebellararteriesandprovidefortheposterior1/3ThearteryofAdamkiewiczarisesfromtheaortatypicallyonthelefthandsideandprovidesthemajorb

5、loodsupplytotheanterior,lower2/3ofthespinalcordMechanismofActionPrinciplesiteofactionisthenerverootSmallermyelinatedfibersareblockedmoreeasilythanlargerunmyelinatedonesSympatheticblockademaybe2segmentshigherthanthesensoryblock,whichisusually2segmentshigherthan

6、themotorblockSympathectomyleadstovariabledecreasesinBP,accompaniedbyadecreaseinheartrateandcardiaccontractilityVasomotortoneisdeterminedbysympatheticfibersarisingT5-T11,whentheseareblockedvasodilationofvesselsoccursinconjunctionwithbloodpoolingHRdecreaseswhenc

7、ardioacceleratorfibers(T1-T4)areblockedTreatment:-volumeloadwith10-20cc/kgofIVFinhealthypatientspriortoplacingepidural-leftuterinedisplacementofpregnantpatientsminimizesphysicalobstructionofvenousreturn-autotransfusewithheaddownposition-treatbradycardiawithatr

8、opine-treathypotensionwithfluidandpressorsContraindicationsPatientrefusalBleedingdiathesisSeverehypovolemiaElevatedICPInfectionatsiteofinjectionSeverestenoticvalvularheartdiseaseVe