BAILYLOVE TEXTBOOK OF SURGERY0 INDEX 7Word文档下载推荐.docx

BAILYLOVE TEXTBOOK OF SURGERY0 INDEX 7Word文档下载推荐.docx

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Anaesthesiaandpainrelief

RICHARDM.LANGFORDandKEITHBUDD

Preparationforanaesthesia

Recognitionofgeneralmedicalandspecificanaestheticriskfactorsfacilitatestheimplementationofpre-emptivemeasuresandimprovespatientsafety.Earlyassessment,liaisonwiththeanaesthetistandappropriateinvestigationsavoidunnecessarydelays.Inanycase,theanaesthetistwhoistobepresentduringtheoperationshouldassessthepatientpreoperativelyandparticipateinthepreparationforsurgery.

Preoperativeevaluationandmanagement

Investigationofthegeneralconditionofthepatientbeforesurgeryshouldbespecificaccordingtothegeneralhistoryandclinicalsigns.Investigationsinfitpeopleareunnecessaryanduneconomic,butindicatedtestsshouldbeperformedasearlyaspossible,preferablybeforeadmission.Routinehaematologicalandbiochemicalscreens,withelectrocardiographyandchestradiography,areprudentinvestigationsinelderlypeoplereceivinggeneralanaesthesiaforallbutminorsurgery.Thesavingofaserumsamplefortransfusioncross-match,acheckforhepatitisantigenandasickle-cellscreen,ifindicated,shouldnotbeforgotten.

Cardiovasculardisease

Uncontrolledhypertensionandangina,dysrhythmiasandcardiacfailurearecommonreasonsforpostponementofelectiveprocedures.Correctionofhypertensionandischaemicheartdiseaseisessentialandneedstobecontinuedthroughtheoperativeperiod,eventhoughthepatientmaybeunabletotakeoraldrugs.Fastatrialfibrillationneedstobecontrolledbeforeanaesthesia.Symptomaticdisordersofsinoatrialconductionrequirepacemakerinsertionbeforeanaesthesia,asdoallcasesofeitherMobitztype2second-degreeblockorthird-degreeheartblock.Inanemergency,transvenoustemporarypacingwiresorexternalpacingcanbeused.Modernvariable-ratedemandpacemakersmayrequireresettingtofixedratemode,butaregenerallystableduringanaesthesia.However,acardiologicalopinionshouldbesought,bipolardiathermyemployedifpossibleandthe.diathermyplateshouldbepositionedsothatthecurrentdoesnotcrosstheheartorpacemakerwires.

Recentmyocardialinfarctionisastrongcontraindicationtoelectiveanaesthesia.Thereisasignificantmortalityfromanaesthesiawithin3monthsofinfarction,andelectiveproceduresshouldideallybedelayeduntilatleast6monthshaveelapsed.

Patientswithvalvulardiseasewillneedcorrectivetreatmentofanypreoperativeinfections,andappropriateperioperativeprophylacticantibioticcover,toavoidsubacutebacterialendocarditis.

Patientswithcardiacdiseaseneedcarefulpreoperativeevaluation.Muchcanbederivedfromadetailedhistoryincludingexercisetoleranceanddrughistory.Echocardiographyhasenablednoninvasiveassessmentofcardiacfunction.Anyelectrolyteabnormality（especiallyhypokalaemia）oranaemiashouldbecorrectedandthecirculatoryvolumeshouldbemaintainedatnormallevel.Perioperatively,thepresenceofanadequateurineoutputisausefulindicatorofadequacyofthecirculatingvolume.

Operativeprocedurescreateanincreaseddemandforoxygenduetopain,surgicalstressandtemperatureloss.Patientswithcardiacdiseasemayneedaperiodofelectivepostoperativemechanicalpulmonaryventilationaftersurgery,untiltheperiodofraisedoxygenconsumptionhaspassed.Thecarefulanaesthetistandsurgeonplansuchcarebeforesurgery.

Respiratorydisease

Thoracicsurgicalproceduresdemandspecificpreoperativetestsofrespiratoryfunctionincludingspirometryandbloodgasanalysis.Ingeneralsurgicalpractice,respiratoryinfectionandasthmaarethecommonproblemsneedingtreatmentbeforeanaesthesia.Inchronicrespiratoryfailure,carefulattentionshouldbegiventoperioperativephysiotherapy,earlymobilisationandtreatmentofinfection.Measurementofoxygensaturationandbloodgastensionspreoperativelygiveaveryusefulguidetofuturevaluesonrecovery.Theneedforpostoperativeventilatorysupportshouldbeanticipated.Regionalanaesthesiaasappropriateisadvantageousinrespiratorydisease.Upperabdominalandthoracicproceduresareunsuitedtoregionalanaesthesiaalone,aspositivepressureventilationundergeneralanesthesiaisnecessary.

Gastrointestinaldisease

Aspirationofgastriccontentscarriesahighriskofacidpneumonitis,pneumoniaanddeath.Regurgitationinthepresenceofahiatushernia,orfrom‘thefullstomach’,mayresultfromemergency（nonstarved）cases,bowelobstructionorparalyticileusandindicatesmandatoryprecautionsduringanaesthesia.Arapidsequenceinductionisconducted,inwhichthepatientis‘preoxygenated’andcricoidpressureisappliedfromlossofconsciousnessuntilthelungsareprotectedbytrachealintubation.Bowelobstructionrequirespreoperativenasogastricaspirationandcarefulcorrectionoffluidandelectrolytebalancebeforeanaesthesiaisinduced.

H2-receptorblockingagentssuchasranitidineareadministeredifthereisanincreasedriskofregurgitation,ideallyatleast2hourspreoperatively.

Anaesthesiainthepresenceofjaundicecarriesahighriskofrenaldamage.Theanaesthetistshouldensurethatnohypovolaemiaoccursandthatagoodurineoutputispresentbeforeinduction,bythepreoperativeinfusionofintravenouscrystalloidsolutions.Adiureticagentshouldonlybeusedifthecirculatingvolumeisfirstassessedtobeadequate.

Metabolicdisorders

Familialporphyriaandhyperpyrexiaarehereditarymetabolicdisordersassociatedwithhighanaestheticrisks.Phaeochromocytomaisalsoassociatedwithsevereanaestheticcomplications.Thepresenceofthesedisordersrequireshighlyspecificpreanaestheticplanning.Diabetesandadrenalsuppressionfromsteroidtherapyarealsocommonmetabolicdisorderswhichcomplicateanaesthesia.

Noninsulin-dependentdiabeticpatientsondietandoralhypoglycemicagentswillneedbloodsugarmeasurementduringanaesthesia.Anintravenousinfusionofglucosemayberequiredifthelong-actinghypoglycemiceffectspersisteveniftheagentwasomittedonthedayofsurgery.

Exceptforminorsurgery,anintravenousinfusionofglucosewithsolubleinsulinislikelytobenecessarywithclosemonitoringandcontrolofbloodsugarlevels.Insulin-dependentdiabetesalwaysneedspreoperativeconversiontocontrolwithrapidlyactingsolubleinsulinbyintravenousinfusionontheoperativeday,andthisiscontinueduntilthepatienthasrecoveredfromtheoperation.Inpractice,formaintenanceofbloodsugarlevels,itisbesttokeepaconstantinfusionof5—10percentglucosewithpotassiumsupplementationthroughaseparateintravenouschannelatabout2litres/24hours.Solubleshort-actinginsulinisgivencontinuouslybyintravenoussyringepump,withtherateindicatedbyfrequent（1—4-hourly）measurementofbloodglucoseconcentration.Theplasmapotassiumlevelneedscarefulcontrol.Thecirculatingvolumeshouldbemanipulatedindependentlyviaaseparateinfusionofnormalsaline,bloodorcolloid.Inthiswayasteadycontrolofbloodglucoseconcentrationcanbeeasilyachievedbyanexperiencednurse.Patientswhoarereceivingcorticosteroidsorwhohavereceivedtheminthepast2monthsrequiresupplementionwithhydrocortisoneduringandaftersurgerytoavoidadrenalinsufficiency（Addisoniancrisis）.

Coagulationdisorders

Whetheriatrogenic（includingtherapeutic）orpathologicalinorigin,coagulationdisordersneedcarefulassessmentbeforesurgerywithacoagulationscreen,orclottingfactorandplateletmeasurements.Inacquireddisorders,suchasdisseminatedintravascularcoagulation,freshfrozenplasmaorcryoprecipitateandplateletsmaybegiventothepatientbytheanaesthetistperioperativelytocontrolhaemorrhage.Patientsreceivingtherapeuticwarfarinneedtoceasetreatmentseveraldayspreoperativelyandhaveprothrombintime（PT）measurementuntiltheInternationalNormalisedRatio（INR）fallstoabout1.5fromthetherapeuticrangeof2.0—4.2.AtanINRof1.5,surgicalhaemostasisshouldbeachieved.VitaminKcanbeusedtohastenthereversalofwarfarinbutitisalong-actingagentandcancauseweeksofresistancetowarfarinaftersurgery,soitisbettertoavoidit.Whentheriskofthrombosisandembolismishigh,anintravenousinfusionofheparincanbeusedtoreplacewarfarin.Theheparincanbestoppedorreversedwithprotaminefortheperiodofsurgery.Rapidcontrolofheparinactivityiseasy,butitisnotsowithwarfarin.

Neurologicaldisease

Incerebraldiseaseandtrauma,hypoxia,hypercarbiaandrespiratoryobstructionraiseintracranialpressureandcancausecerebraldamage.Inthepresenceofdeterioratingconsciousness,managementoftheairwayandventilationisofprimeimportance,andespeciallysointraumaticinjuryinwhichearlyendotrachealintubationandpulmonaryventilationshouldprecedesupinepositioningforcomputedtomography（CT）ofthebrain.Particularcareoftheneckduringintubationisnecessaryifacervicalfractureissuspected.Skulltractionandawakeintubationunderlocalanaesthesiaaresometimesused.

Anticonvulsantdrugsmustbecontinuedduringsurgeryonepilepticpatients,andthismaynecessitateusingintravenousadministration.

Inperipheralneuropathiesandmyopathies,theneedforprolongedperiodsofpostoperativeventilationshouldbeanticipated.

Anaesthesiaandpsychiatricdisease

General,ratherthanregional,anaesthesiaisusuallynecessary.Tricyclicantidepressantsandmonoamineoxidaseinhibitordrugspotentiatesympathomimeticagentssoadrenalineandcocainemustbeavoided.Pethidinecanalsocausehypertensionwiththesedrugs.Othernarcoticanalgesicagents