局部麻醉(英文版)课件

Anesthesia

Localanesthesia

wangjieUnionHospitalHistoryCocaplantleavesinPeru.Cocainewasisolatedin1860Firstusedasalocalanestheticin1884.Procainein1904.lidocainein1943,Bupivacainein1957andprilocainein1959.DefinitionLocalanesthesiaisanytechniquetorenderpartofthebodyinsensitivetopainwithoutaffectingconsciousness.Alocalanestheticisadrugthatreversiblyinhibitsthepropagationofsignalsalongnerves.Analgesia(lossofpainsensation)Paralysis(lossofmusclepower)LocalAnestheticsPharmacologyClassificationStructureAminoesters:procainetetracaineAminoamides:bupivacainelidocaineropivacaineEffectiveTimeShortterm:procaineMiddle:lidocaineLong：bupivacainetetracaineropivacaine(pKa)=pH-log[B]/[BH+]

OnsetTime

BasesIonicpositiveionPharmacology2.LipidsolubilityItseffectononsetispoorlyunderstoodhighlipidsolubilityincrateofdiffandshortenonsettimeBUTitalsoincsolubilityinthesurroundingtissuePharmacologyPlasmaconcentration:dependsonabsorptionkineticsHOWWHEREsystemicdispositionkineticsDistributionEliminationmetabolism

PlasmaEZLiverEZexcretionPharmacologyPHARMACOKINETICSAbsorptionofLASiteofinjection(intercostal>caudal>brachialplexusetc)Dosage(bloodlevelofLArelatedtototaldoseofdrugratherthanspesificvolumeorconcentrationofsolutionAdditionofvasoconstrictorMetabolismofLAA.ESTERSRapidhydrolysisbyplasmacholinesteraseWatersolublemetabolitesexcretedintheurine(p-aminobenzoic,diethylaminoethanolAbnormalpseudocholinesteraseincriskoftoxicsideeffectCSFlackofesteraseenzymeExceptionCocain-partiallymetabolizedinliverandpartiallyexcretedinurineunchangedCont.B.AMIDEEnzymaticdegradationinliverbymicrosomalenzymes(prilocaine>lidnocaine>mepivacaine>bupivacaineandetidocaine)MuchslowerthanesterhydrolysisN-dealkylation,aromaticandamidehydrolysisDecreasehepaticfunctionorhepaticbloodflowreducemetabolicratepredsystemictoxicityVerylittledrugexcretedunchangedbykidneyMechanismofactionInhibitingsodiuminfluxthroughsodium-specificionchannelsinparticulartheso-calledvoltage-gatedsodiumchannelsactionpotentialcannotariseandsignalconductionisthusinhibitedLocalanesthetics

Sideeffect1.Toxicity2.Hypersensitivity/AllergyUndesiredeffects!!!Toxicity

mayoccurif

ThemaximumsafedoseisexceededTransienthighbloodlevelsareachievedbyaccidentalintravenousinjectionRapidabsorptionfromaninflamedorvascularareaUsenormaldosetoweakpatientsLocalanesthetics

SideeffectCentralnervoussystemExcitatoryorDepressive

Atlowerconcentrations,arelativelyselectivedepressionofinhibitoryneuronsresultsincerebralexcitation,whichmayleadtogeneralizedconvulsions.

Aprofounddepressionofbrainfunctionsoccursathigherconcentrationswhichmayleadtocoma,respiratoryarrestanddeath.CardiovascularsystemBradycardia,buttachyarrhythmiacanalsooccur.Withhighplasmalevelsoflidocainetheremaybehigher-degreeatrioventricularblockandseverebradycardia,leadingtocomaandpossiblydeath.ManagementoftoxicityOxygenation:theairwayismaintainedandoxygenadministeredbyface-mask,usingartificialventilationifapnoeaoccursManagementoftoxicityControlofconvulsions:withsmallincrementsofeitheriazepam(5mg)orthiopentone(50mg).ButexcessivedosesshouldnotbegivensincecardiorespiratorydepressionmaybehappenManagementoftoxicityCirculatorysupport:hypotensionmayneedtobetreatedwithvasopressorsorinotropes(e.G.Ephedrinein10mgincrements).Arrythemiamustbemanagedandifcardiacarresthappened,CPCRshouldbeperformedimmediatelylidocainepKa7.85Plainaqsolution1,1.5,2%@pH5-7Solutionwithadrenalin@pH3-4.5Ralativepotency2T1/2ßadult1.8hr,neonate2hrXtremelystableMaxdose:plain3mg/kg,adrenalin7mg/kgE.A.of400mg/70kg@[blood]=2-4ug/mlToxicitybegin@5ug/mlRelativelyquicklyabsorbedfromGITMetabinliver(dealkylation)excretedurineToxicdoseleadtodeathbyVForcardiacarrestSuitableforsurface,infiltration,nerveblock,caudal,epiduralandSABupivacainepKa8.1Plainaqsoln.25,.375,.5%@pH4.5-6IfwithadrenalinpH3.5-5.5Potency8Proteinbinding95%>lipidsolubilitythanlidocaineT1/2ßadult3.5hr,neonate8.1-14hrAmidelinkLAProdprolongedanaesthesiawithsloweronsetAddadrenalin-toxicity,h/enochangeindurationPostopanalgesia:IC7hr,EA3-4hrEpid/caudalpeak[plasma]30-45minLowerfoetal/maternalratiocflidnocaine(!Proteinbinding)Maxdose:plain/withadrenalin2mg/kgRopivacaineChemicalanalogueofbupivacaineThemoleculeisdesignedtomodifythespesificcardiotoxicityassociatedwithbupivacainepKa8.2andpHsolution5.5-6.0EquallypotentasbupivacaineItsqualityofclinicalblockappeartobeverysimilarinonset,durationandqualitythatofbupivacaineNospesifictoxicityhasbeendetectedLocalanesthesia

MethodsLocalanesthesiaSurfaceanesthesiaLocalinfiltrationanesthesiaRegionalblockNerveblockPhysiologyCSF：120～150ml(space23～30ml)，pressurelieononeside70～170mmh2o，siteposition200～300mmh2o。

AssociatedwithdistributionoflocalanestheticsEffectSiteSpinalnerverootSpinalanesthesia:DirectaffectEpiduralanesthesia:

(1)InfiltratinginCSF(2)SpinalnerveSequenceofnerveblocksympatheticnerveEstheticnerveMotornerveDifferentialblock

(Ropivacaine)Lowerdosesorconcentrationsmayselectivelyinhibitpainsensationwithminimalaffectonmusclepower.Sometechniquesofpaintherapy,suchaswalkingepiduralsforlaborpainusethiseffect,termeddifferentialblock.SpinalBlockAmoredenseblockFastonsetUsedmoreoftenforC/SCommon