论血透导管的选择(4)

国外文献

Optimalhemodialysiscatheterselection

by99.9%inthecathetertunnelforaperiodof21days.ThecompanyhasperformedsuccessfulinvitrotestsagainstS.epidermidis,S.aureus,Pseudomonasaeruginosa,C.albicans,Enterococcusfaecalis,andE.coli.51

Antibiotic-impregnatedcathetershavealsoshownsigni -cantanti-infectivebene t.Antibiotics,mostcommonlyacombinationofminocyclineandrifampicin,coatboththeinnerandoutersurfacesofthecatheter.Therehavebeenmanyclinicaltrialsofcoatedcatheterscomparedwithun-coatedcontrolsorhead-to-headagainstothercoatings.Ina2008reviewof37oftheserandomizedcontrolledtrialsin-volving11,586patients,GilbertandHarden52concludedthatheparin-coatedandantibiotic-impregnatedCVCsledtosigni cantreductionsincatheter-relatedbacteremia,whilenostrongevidenceexistedforantisepticcathethers(coatedwithchlorhexidineandsilversulfadiazine,orsilverimpreg-nated).Allrelativeriskcalculationsfromthestudiesindicateastrongpositiveeffectofantibioticcoatingontherateofcatheter-relatedbloodstreaminfection.However,thereisalsosomeevidenceofantibioticresistancefrominvitrostud-ies.Additionally,onlytwomajorprospectivestudiesin-volvedaveragecatheteruseover2weeks,raisingtheques-tionofantibioticimpregnationlongevity.53,54

Recently,Angiotechreceived510kclearanceonaCVCcoatedwith5- uorouracil(5-FU).Since5-FUisnotusedroutinelyinhospitalsasanantibiotic,thedrughastheuniqueabilityofinhibitingbacterialgrowthandmetabolicfunctionsofmostmicro-organismswhilereducingtheriskforcreatingresistantstrains.Coatingacatheterwithamini-malamountof5-FUrendersthesurfacehostileformicrobes,withoutsigni cantchangesinpatienttolerabilitypro le.55ThedatafromAngiotech’s960patientclinicaltrialcompar-ingits5-FUCVCwithachlorhexidine/silversulfadiazine(CH-SS)coatedCVCshownoninferiority.However,the5-FUdeviceappearstobesuperiorinthenatureofthecol-onizationsandinfections:whilethe5-FU-coatedCVCswerecolonizedwithS.epidermisandothercommoncontaminants,thecatheterswithCH-SSwerealsocolonizedwithmethicil-lin-resistantS.aureus,E.coli,Klebsiellapneumoniae,Proteusmirabilis,S.marcescens,andAscinetobacterbaumannii.56

CatheterLumenandTipDesign

Severallumendesignshaveemergedovertheyears.Theearliesttunneledcuffedcatheter,thePermCathbyQuinton,wasalarge,ovalshapewithtwoseparatelumens.Subsequentimprove-mentshaveincludedaroundlumenwithacentralwall,twoseparatesinglelumencathetersfordifferentialplacementofthein owandout owcatheter(Tesio,MedComp),andfusionofthetwosinglelumensatadistalpointalongtheirlengthforeasierinsertion(AshCatheter,Medcomp).21

Twokeyprospectiverandomizedstudieshavedemon-strated,whiledoublelumenandtwosinglelumencathetersdonotleadtoappreciabledifferencesinsurvivalorinfectionrate,doublelumencathetersshouldbechosenfortheireaseofuse.38,57Inarandomizedtrialof64patients,Trerotolaandcoworkers58concludedthattheAsh-splitcatheterandOpti- owduallumencatheterhadnodifferencesincatheter-re-latedbacteremiaandlate owproblems.Richardandco-workers57compared38Ash-split,39Opti- ow,and36Tesiocatheters.TheTesiocatheter(twosinglelumens)requireda

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signi cantlylongerperiodoftimeforinsertion(mean42minuteversus29-30minutefortheothercatheters),leadingtomoreinsertioncomplications.However,mean owratesandcatheter-relatedinfectionswerenotsigni cantlydiffer-ent.Thesestudiesdemonstrate,intheabsenceofbene tsinpostinsertioncomplications,easeofusemaybettergovernlumenchoice.

Commonlyusedlong-termhemodialysiscathetershaveastaggeredtipdesign,meaningthattheout owtipextendsseveralcentimeters(typicallyaminimumof2.5cm)beyondthein owtip,topreventrecirculation.Anothercommontraditionaldesignisthesplit-tipordual-catheterdesign.Theoriginalsplit-tipcatheteristheAshSplit,designedbyDr.AshandmarketedbyMedcomp.Thiscatheterhasmanysideholes,thoughttofacilitategoodfunction.Amorerecentver-sionofthesplittipcatheteristheCentroscatheter,alsodesignedbyDr.Ash.Therationalebehindeliminatingthesideholesinthismodelisthatthelackofirregularsurfacessurroundingthesideholeswouldimprovecatheterfunctionandsurvivalandmayalsoreduceinfections.

Despitetheevolutionoftipdesign,therearefewstudiesonthein uenceoftipgeometryonpatientoutcomes.ThestudybyRichardandcoworkers57comparingthreedifferenttipdesigns(Tesiodualcatheterwithsideholes,AshSplitTipwithsideholes,andOpti- owduallumenstaggeredtipwithsideholes)didnotshowhemodynamicorcathetersurvivaladvantageforanyonecatheter.Theplethoraofmultiplesideholedesignsonthemarketre ectsthebeliefthatbackupin owisnecessaryinthecaseofobstruction.However,sideholescanalsocausethrombosisduetotheirregularityoftheircutsurfaces.Inarecentcomparisonoftwosimilarchronicdialysiscatheterswithandwithoutsideholes,Talandcoworkers59demonstratedreducedbacteremiainthenon-side-holecathetersandattributedtheresulttoreducedthrombusformationatthecathetertip.Mareelsandcowork-ers60presentedahemodynamiccomputermodeldemon-stratingthat,inamultiplesideholecatheterdesign,the rstavailableholeisprimarilyemployed.Thedistalholesap-pearedtocomprisealow owzone,suggestinganincreasedclottingrisk.Thereisalsoevidencethatsideholescanpre-ventlockingsolutionfromreachingtheareabetweenthesideholeandcathetertip,precipitatingclotformationatthetip.61,62Clotsmaybecome rmlyanchoredtothewallsaroundsideholes,presentingadif cult-to-managesitua-tion.62

Acommondrawbackofmanyofthecurrentcatheterde-signsishighlevelsofrecirculationonlumenreversal,leadingtosubsequent owfailure.Reversalofthelumensinlong-termdialysiscathetersisusuallyperformedtocorrectinade-quatein ow,wherethein owthroughthearteriallumenisinadequate.19However,reversalof owalsoleadstotheun-desirableeffectofrecirculation,wherebydialyzedbloodex-itingfromonelumendirectlyenterstheotherlumen,bypass-ingsystemiccirculation.Recirculationofbloodduringdialysisreducestreatmentef ciencyandcanleadtoadversehealthoutcomes.63,64

AmorerecentcatheterdesignedtoaddresstheproblemofrecirculationistheTalPalindromecatheter.Inthisdesign,thearterialandvenoustractshavethesamelength.Whilein owoccursthroughthesideslotandthemostproximalportionoftheendhole,out owoccursasajetdirectedaway