REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
Official Publication of the Brazilian Society of Anesthesiologywww.sba.com.br
REVIEW
ARTICLE
Clinical
application
of
thoracic
paravertebral
anesthetic
block
in
breast
surgeries
Sara
Socorro
Faria
a,
Renato
Santiago
Gomez
b,c,∗aUniversidadeFederaldeGoiás(UFG),Goiânia,GO,Brazil
bDepartmentofSurgery,FaculdadedeMedicinadaUniversidadeFederaldeMinasGerais(UFMG),BeloHorizonte,MG,Brazil
cHospitaldasClínicasdaFaculdadedeMedicinadaUniversidadeFederaldeMinasGerais(UFMG),BeloHorizonte,MG,Brazil
Received11July2013;accepted29July2013 Availableonline26November2014
KEYWORDS
Paravertebralblock; Breastcancer; Postoperative complications
Abstract
Introduction:Optimumtreatmentforpostoperativepainhasbeenoffundamentalimportance insurgicalpatientcare.Amongtheanalgesictechniquesaimedatthisgroupofpatients, tho-racicparavertebralblockcombinedwithgeneralanesthesiastandsoutforthegoodresultsand favorablerisk---benefitratio.Manylocalanestheticsandotheradjuvantdrugsarebeing investi-gatedforuseinthistechnique,inordertoimprovethequalityofanalgesiaandreduceadverse effects.
Objective: Evaluatethe effectiveness andsafetyofparavertebral blockcompared to other analgesicandanestheticregimensinwomenundergoingbreastcancersurgeries.
Methods:Integrativeliteraturereviewfrom1966to2012,usingspecifictermsincomputerized databasesofarticlesinvestigatingtheclinicalcharacteristics,adverseeffects,andbeneficial effectsofthoracicparavertebralblock.
Results:Ontheselecteddate,16randomizedstudiesthatmettheselectioncriteriaestablished for thisliteraturereviewwereidentified. Thoracicparavertebralblockshowed asignificant reductionofpostoperativepain,aswellasdecreasedpainduringarmmovementaftersurgery.
Conclusion: Thoracicparavertebralblockreducedpostoperativeanalgesicrequirement com-paredtoplacebogroup,markedlywithinthefirst24h.Theuseofthistechniquecouldensure postoperativeanalgesiaofclinicalrelevance.Furtherstudieswithlargerpopulationsare nec-essary,asparavertebralblockseemstobepromisingforpreemptiveanalgesiainbreastcancer surgery.
© 2014SociedadeBrasileirade Anestesiologia.Publishedby ElsevierEditoraLtda.Allrights reserved.
∗Correspondingauthor.
E-mail:renatogomez2000@yahoo.com.br(R.S.Gomez). http://dx.doi.org/10.1016/j.bjane.2013.07.018
PALAVRAS-CHAVE
Bloqueio paravertebral; Câncerdemama; Complicac¸ões pós-operatórias
Aplicac¸ãoclínicadobloqueioanestésicoparavertebraltorácicoemoperac¸õesde
mama
Resumo
Introduc¸ão:Oadequadotratamentodadorpós-operatóriatemsidodefundamental importân-cianoscuidadoscomopacientecirúrgico. Entreastécnicasdeanalgesiadirecionadaspara essegrupodepacientes,obloqueioparavertebraltorácicocombinadocomaanestesiageral sedestacapelosbonsresultadosepelafavorávelrelac¸ãorisco-benefício.Muitosanestésicos locaiseoutrosfármacosadjuvantesvêmsendoinvestigadosparausonessatécnica,comvistas amelhoraraqualidadedaanalgesiaereduzirosefeitosadversos.
Objetivo:Avaliaraeficáciaeaseguranc¸adobloqueioparavertebralemcomparac¸ãocomoutros regimesanalgésicoseanestésicosemmulheressubmetidasacirurgiasparacâncerdemama.
Métodos: Revisãointegrativadaliteraturade1966a2012,feitapormeiodetermosespecíficos nosbancosdedadosinformatizados,deartigosqueinvestigaramascaracterísticasclínicase osefeitosadversosebenéficosdobloqueioparavertebraltorácico.
Resultados: No período selecionado, foram identificados 16 estudos randomizados que preenchiamoscritériosdeselec¸ãoestabelecidos paraessarevisãobibliográfica.Obloqueio paravertebraltorácicodemonstrouumareduc¸ãosignificativadadorpós-operatória,bemcomo diminuic¸ãodadordurantemovimentosdobrac¸oapósacirurgia.
Conclusão:Obloqueioparavertebraltorácicoreduziu anecessidadepós-operatóriade anal-gésicosquandocomparadoaogrupoplacebo,notadamentedentrodasprimeiras24horas.O empregodessatécnicapoderiagarantirumaanalgesiapós-cirúrgicaderelevânciaclínica.Novos estudos,com maioresgrupos populacionais,fazem-se necessários,uma vez que obloqueio paravertebralparecepromissoremanalgesiapreemptivaparacirurgiadecâncerdemama. ©2014SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Todosos direitosreservados.
Introduction
Inrecentyears,thenumberofnewcasesofbreastcancer hasincreased,withan estimatedrisk of 52cases per100 thousandwomen.1Similartothatseenintheworld
popula-tion,breastcancerbecametheleadingcauseofmortality amongwomen.2,3About40%ofthepatientsexperience
clin-icallysignificantacutepostoperativepain(>5ontheVisual AnalogScale).Thisindicatesthat,asinothersurgical pro-cedures,paintreatmentis notsufficient. Moreover,acute postoperativepain is a major risk factor for chronic pain development in women following breast surgery.4
There-fore,a therapeutic approach to pain after breast cancer surgeryisnecessary.
Paincontrolafterbreastsurgeryproceduresiscritical.In addition,thereis theneed fortreatmentofpostoperative comorbidities,aswell asnauseaandvomiting,considered asthe three main variables related torestriction of hos-pitaldischargeinpatientsundergoingsurgical procedures, suchasquadrantectomyandmastectomy.Nauseaand vom-iting arerelatively under controlwith the advent of new antiemeticagents.Paravertebralblockadehasbeenshown tobe a viable option tothe classical multimodal analge-sia,particularlyinrecentyearswiththeuseofopioidsand anti-inflammatorydrugs.5
Withtheadventofultrasoundtoguideanestheticblocks, itsusehasbecomeapreoperativeassessmenttoolthat pre-dicts the possibilityof performing a neuraxial blockade.6
The useof this ancillarystudy can help preventinjury to
structures suchasvessels andpleura, aswell as allowing accurateinjectionoflocalanestheticunderdirect visualiza-tion.Apreviousstudyreportedthatthoracicparavertebral block(TPVB)maybeconsideredanefficientoptionthat pro-videsanesthesiaandpostoperative(PO)analgesiaforbreast surgery,aswellasareductioninpainintensityandnausea andvomitingdrugconsumption.7
Despitethegrowingnumberofarticlesassessingthe post-operativemanagementofacuteandchronicpain,wefound nointegrativereviewassessingthetopicinquestion.Thus, theaimofthisstudywastoassesstheefficacyandsafetyof TPVB,comparedwithotheranalgesicsandanesthetic reg-imens, tocontrol post-surgicalpain inwomen undergoing breastcancersurgery.
Methods
Integrative literature review of randomized and/or
double-blind studies, with population and hospital
approaches. The search was conducted in the
follow-ingcomputerizeddatabasesduringFebruary2013:PubMed (http://www.pubmed.gov), Cochrane Controlled Trials Register (Central, The Cochrane Library --- http://www. thecochranelibrary.com.br),Embase(http://www.embase. com),andLilacs(http://lilacs.bvsalud.org).
The limits used for literature search were:
English or Spanish publications, female human,
surveyed from 1966 to 2012. The terms used to
82 articles identified in databases
50 potentially relevant studies
15 articles were unreadable, according to predefined criteria (non-randomized trials, 3 studies
in Russian language).
20 studies excluded due to irrelevance to the specific topic
15 articles with useful information included in the integrative review
Figure1 Systematizationofthestudyselectionprocess.
postoperative analgesia [MeSH], postoperative chronic pain[MeSH],paravertebralblock[MeSH],andpreincisional paravertebral block [MeSH]. The articles that answer the establishedguidingquestionandmetthefollowinginclusion criteria were adopted: studies assessing effects, clinical characteristics,efficacy, andsafetyofparavertebralblock associated with general anesthesia (GA) and placebo-controlled in women undergoing breast cancer surgery; randomizedtrialsindexedintheabovementioneddatabase from1966to2012,whoseabstractswereavailableonline. Exclusion criteria were non-randomized publications, editorials,reviews,andcasereports.
The selected articles (Fig. 1) were read in full and analyzed based on a checklist considering the following characteristics: study type and design, year and place; assessmentmethods;numberofparticipants(inclusion cri-teria, age group, type of surgery, anesthetic technique, study objectives,control algorithmfor painmanagement, useoffixeddrugforpostoperativepaininbothstudygroups ---TPVBandGAorplacebo,prophylaxisagainstpostoperative vomiting);majorclinicaloutcomes.
Results
Intotal,82studieswereidentifiedofwhich15metthe inclu-sion criteria(Fig.1). Selectedarticles were inserted in a table(Table1)tobecompared.Besidesthese,other docu-mentshavebeencitedthroughoutthisreviewfortheoretical basisandtopicdiscussion.Studiesthatclearlydidnotmeet theinclusioncriteriawereexcludedandcopiesoftextsthat werepotentiallyrelevantwereobtained.
Of the 15 studies included, 825 participants undergo-ingbreastsurgerywererandomlyassignedtointervention or control groups. Typesof surgery were:tumor removal, mastectomy with or without axillary dissection,
quad-rantectomy, and mastectomy followed by immediate
reconstruction.Onlyoneinvestigatorreporteddetailed sur-gical statistics and data operation.7 The main inclusion
criteriafortheresearchwere:adults(over18yearsofage) andASAphysicalstatusclassI---III,accordingtotheAmerican Society of Anesthesiologists (ASA). Coagulation disorders, treatmentwithanticoagulants,allergytolocalanesthesia, and infection at the site of injection were the exclusion criteriainallstudies.
The techniquedescribed by Easonand Wyattwasused toestablishTPVB.8 Localanesthetic wasinjectedintothe
paravertebralspacebetweenthethirdandfourththoracic levels.The most commonly administeredlocal anesthetic was0.25---0.5%bupivacaine7,9---12;2% lidocainewasusedin
one study,13 while another tested a mixture of 2%
lido-caine, 0.5% bupivacaine with epinephrine, fentanyl, and clonidine.14Theadditionoffentanyl(0.05%)wasassociated
withnauseaandvomiting,whileclonidineresultedin hemo-dynamicchanges(arterialhypotension).14Levobupivacaine
(0.1%) administered alone was not effective in the TPVB analgesia after breast surgery. Ropivacaine (0.5%) acted fasterand offeredincreasedanesthesiatime.15---17 Inmost
studies,the main agents usedfor induction of anesthesia werepropofol,fentanylorsufentanil.Thiopentalwasused in one study.13 Analgesia was provided by bolus
adminis-tration of various opioids. Different additional analgesics (acetaminophen,traditionalnonsteroidalanti-inflammatory drugs [NSAIDs], coxibs) were distributed in all works. In orderto reduce the prevalence of POnausea and vomit-ing,dexamethasone,ondansetronorbothwereusedbefore theoperation,accordingtotheprotocolofeachinstitution. Patients were ventilated with carbon dioxide absorption anestheticsystemandpositivepressuremechanical venti-lation.
TherewasasignificantdifferencebetweenTPVBandGA groupsregardingthescoresof‘‘worstpostoperativepain’’ <2h, 2---24h, and 24---48h. Heterogeneity influenced the resultsatalltimes.Differentdataonlevelsofpainatrest wereselectedintwostudies9,10andtherewasonlyaslightly
betterpainscoreduringalltimesevaluatedinTPVBgroup, althoughnotstatisticallysignificant. Therewassignificant reductioninlevels ofpain atrest in the periodof2---24h andatalltimesduringmovement.Fivestudies,10---14 which
includeddatafrom215patients,comparedlevelsofacute postoperative(VAS/NRS)paininwomenundergoingsurgery withTPVB and GA comparedwith GA alone in the treat-mentofacutepostoperativepain.There wasa significant differenceinthe levelsof ‘‘worstpainduringthe postop-erativeperiod’’ between TPVBand control groups (<2h). Dataontheneedforrescueanalgesiawereassessedinfour surveys.11---14 Fewerpatientsrequiredopioidsduring0---24h
aftersurgerywithTPVBandGAcomparedwithGAalone. TPVBgroupalsorequiredalesseramountofmorphineduring theintervalof0---24h.
Fourstudies11---14thatincluded248womenreported
accu-ratelythenumberofpatientswhosufferedadverseeffects aftersurgerywithTPVBandGAcomparedwithGAalone. Therewerenoreportsofnervedamageoraccidental pneu-mothorax.Itis noteworthythatTPVBmayhaveprevented an increase in painintensity in breast region after radio-therapyinpatientswhohadnoaxillarydissection.Analgesic effectdurationinTPVBandGAgroupwastwiceashighwhen comparedtocontrolgroup(GA).
Discussion
Table1 Maincharacteristicsofstudiesofparavertebralblockadeinbreastcancersurgery.
Author,year, place
Population(n) Studytype Meanage Assessment method
Studyobjective Anesthetics Blockaderoute Anesthetictechnique details
Complications Mainresults
Puschetal., 1999;Austria
86 42---GA; 44---TPVB
Prospective GA:53years; TPVB:51years
VAS CompareTPVBwith GAinbreastcancer surgery (quadrantectomy, simplemastectomy; mastectomyand axillarydissection)
(1)TPVB:injectionof 5%bupivacaine (0.3mLkg−1)inthe
T4level(maximum doseof150mg); (2)GA:IVinduction ofpropofol (2---3mgkg−1)and
fentanyl(2.3mcg); (3)SPVB
Vomiting GA:12patients; TPVB:4patients
TPVBwasagood alternativetobreast cancersurgery,with goodresults
Kleinetal., 2000;North Carolina
59 30--- GA; 29---TPVB
Randomized, prospective, and double-blind
GA:44years; TPVB:48years
VAS;NRS CompareTPVBwith GAinpatients undergoingbreast reconstructionafter breastcancer
(1)TPVB:injectionof 4mLof0.5% bupivacainewith1: 400,000epinephrine inT1---T7level; (2)GA:induction withpropofol (1.5---2mgkg−1),
fentanylwith isoflurane (1---3mcgkg−1),and
NOinoxygen; (3)MPVB
Vomiting 30min---TPVB×GA
(p=0.11); 1h---TPVB×GA
(p=0.26); 24h---TPVB×GA
(p=0.04)
TPVBwasasurgical alternativetobreast reconstruction, offeringlesspainand nauseacomparedto GAalone
Terheggen etal.,2002; Arnhem/ Netherlands
25 10---TPVB; 15---GA
Randomizedand prospective
TPVB:48years; GA:51years
VAS Evaluatethe effectivenessofTPVB withGAinpatients undergoing quadrantectomywith orwithoutsentinel lymphnode
(1)TPVB:injectionof 5%bupivacaine (15---20mL)with1: 200,000epinephrine, throughacatheter insertedatT3---T4 interspace.Catheter wasremovedafter surgery; (2)GA:induction withfentanyl (1---1.5mcgkg−1)and
propofolinfusion (3---5mcgmL−1);with
mixtureofoxygen andNO(1:2); (3)SPVB
(1)Dyspneaand hypotension(1TPVB patient); (2)Accidentalpleural puncture(1TPVB patient); (3)Therewasno complicationinGA group
TPVBrisk---benefit showednofavorable resultsforthistype ofsurgery
Kairaluoma etal.,2004; Finland
60 30--- TPVB; 30---GA
Randomized TPVB:52years; GA:55years
VAS;Motion evaluation (flexionand abduction)
Assessthepossible effectsofTPVBwith bupivacaineorsaline beforeGA
(1)TPVB:bupivacaine 5mgmL−1inT3level
andlidocaine2---5mL; (2)GA:induction withpropofol (2---3mgkg−1).
Sevofluraneand40% oxygen(BIS monitoring).All patientswere intubatedand ventilatedwithPPVC; (3)SPVB
Vomiting GA:17patients; TPVB:10patients; p=0.069
‘Therewassignificant differencebetween groups.TPVBallowed greatermovementof theshoulder;less pain(p=0.019). Therewasrapid recoveryof psychomotor function,aswellas ocularcontrolin TPVBgroup
Iohometal., 2006;Ireland
29 15---GA; 10---TPVB
Randomizedand prospective
GA:59years; TPVB:65years
VASMcGillPain Questionnaire
Comparetheeffects oftwoanalgesic regimensandthe probabilityofchronic paindevelopment afterbreastsurgery; Associateplasma concentrationsofNO andthelikelihoodof subsequent developmentof chronicpain
(1)TPVB:1% lidocaine(2---5mL)at T3level; (2)GA:induction with8%sevoflurane in100%oxygen; (3)CPVB
Onepatientingroup CPVBdeveloped Horner’ssyndrome
Therewasno associationbetween NOandthe subsequent developmentof chronicpainafter axillarydissection
Kairaluoma etal.,2006; Finland
60 30---TPVB; 30---GA
Randomized, prospective, and double-blind
--- VAS;POMS;NRS DetermineifTPVB wouldbeassociated withlessneuropathic painaftersurgeryfor breastcancer (axillarydissection andsentinelnode)
(1)TPVB:0.5% bupivacaine (1.5mgkg−1)atT3
level; (2)GA:induction withpropofol (2---3mgkg−1).
Sevofluraneand40% oxygen(BIS monitoring).All patientswere intubatedand ventilatedwithPPVC; (3)SPVB
Therewereno reportsof postoperative complications
Table1 (Continued)
Author,year, place
Population(n) Studytype Meanage Assessment method
Studyobjective Anesthetics Blockaderoute Anesthetictechnique details
Complications Mainresults
Burlacuetal., 2006;Ireland
52 (1)13---19mLof levobupiva-caine---TPVB; (2)19mLof levobupiva-caineand 0.25%fentanyl ---TPVB; (3)19mLof levobupiva-caineand 0.25%clonidine --- TPVB; (4)Control group---GA
Group1:51 years; Group2:54 years; Group3:53 years; Group4:57 years
Randomized VAS;OAA/S Comparethe different postoperativeeffects betweenGAand TPVB
(1)Group1:19mL bolus levobupivacaine 0.25%plus1mLsaline followedbyan infusionof levobupivacaine 0.1%; (2)Group2:19mL bolus levobupivacaine 0.25%plusfentanyl 50mgmg(1mLde volume)followedby infusionof levobupivacaine 0.05%withfentanyl 1gmL−1
(3)Group3:19mL bolus levobupivacaine 0.25%plusclonidine 150mg(1mLvolume) beforesurgical incision,followedby aninfusionof levobupivacaine 0.05%withclonidine (3mgmL−1)atT3
level; (4)GA:induction withpropofol (2---3mgkg−1);
(5)CPVB
Nausea (p=0.04)
TPVBsignificantly decreased postoperativepain (quadrantectomy, mastectomy,and mastectomyfollowed byimmediate reconstruction)
Molleretal., 2007; Denmark
79 38---TPVB; 41---GA
TPVB:57.6 years; Placebo:57.2 years Randomized, double-blind
NRS;PONV Examinewhether TPVBalongwith propofoland laryngealmask performedbeforeGA improves postoperative analgesiain mastectomywithSNB ortumorresection
(1)TPVB:0.5% ropivacaine(30mL); lidocaine(5mL)in transverseprocessat C7---T5level; (2)GA:propofol (2---3mgkg−1)and
fentanil; (3)MPVB
(1)Nausea---TPVB andGA(7)/placebo (9);
(2)Vomiting---TPVB andGA(2)/placebo (1);
(3)Sleepdisorders ---TPVBandGA (8)/placebo(7)
Fentanylconsumption wassignificantly lowerinTPVBgroup duringanesthesia. Painseveritywas lowerinTPVBgroup withp<0.0001
Dabbagh,Elyasi; 2007;Iran
60 30---TPVB; 30---GA
--- Randomized NRS Comparewhether TPVBintervenes positivelyinpain scores,morphine consumptionas rescueanalgesia,and lengthofhospital stayaftersimple mastectomy
(1)TPVB:injectionof 2%lidocaine(15mL) atT4level; (2)GA:thiopental withhalothane (4---5mgkg−1)ina
mixtureof1:1NO andoxygen; (3)SPVB
Therewereno reportsof postoperative complications
TPVBproducedfewer complications, decreasedpain intensity,canbean alternativemethod forbreastsurgery
Sidiripoulou etal.,2007; Italy
48 24---TPVB; 24---GA
TPVB:64years; GA:67years
Randomized VAS;Motion evaluation (shoulder abductionand exter-nal/internal rotation)
CompareGAand TPVBregarding analgesicefficacy andmorphine consumptionafter mastectomy
(1)TPVB:2% lidocaine(5mL)at T1---T5levels; (2)GA:inductionof propofoland sufentanil (0.3---0.5mcgkg−1);
(3)SPVB
Nauseaandvomiting (1)TPVBandGA:5 patients; (2)Placebo:15 patients
Vomitingwasmore frequentinGAgroup. Morphine consumptiondidnot differbetweenthe twogroups. Incidenceofnausea andvomitingwas lowerinTPVBgroup
McElwainetal., 2008;Ireland
37 (1)15min:19; (2)30min:18
(1)15min:55 years; (2)30min:54 years
Prospective, randomized, double-blind
VAS Comparepainscores betweenTPVBand GA
(1)15min ---levobupivacaine ---0.2%(bolus:3mL); (2)30min ---levobupivacaine ---0.2%(bolus:8mL); (3)GA:inductionof 0.25%
levobupivacaine 20mLbolus (paracetamol1g; diclofenac75mg;, ondansetron4m;, morphine 0.15mgkg−1)
Horner’ssyndrome, asymptomatic bradycardia, infection,catheter disconnection
Table1 (Continued)
Author,year, place
Population(n) Studytype Meanage Assessment method
Studyobjective Anesthetics Blockaderoute Anesthetictechnique details
Complications Mainresults
Bougheyetal., 2009;United States
80 41---GA; 39---TPVBwith GA
GA:57.9years; TPVB:53years
Prospectiveand randomized
NRS Evaluatetheeffect ofGAusingTPVB. Theobjectiveispain controlafter mastectomywithout plasticreconstruction
(1)TPVB:1%and5% ropivacainewith 1:400,000 epinephrineatT1---T6 level;
(2)GA:monitored cardiovascular parameters; 3---6mLof5% ropivacainewith 1:4,000,000 epinephrine; prophylaxisfor nauseaandvomiting (dexamethasone, ondansetron,and promethazine) (3)MPVB
Therewasno differencebetween groupsinscoresfor nauseaandvomiting andother complications
TPVBsignificantly decreased postoperativepain
Buckenmaier etal.,2010; Pennsylvania
73 (1)23 ---Placebo; (2)27 ---CPVB+GA; (3)26 ---CPVB+GA
(1)Placebo: 58.4years; (2)54.3years; (3)54.8years
Prospective, randomized, double-blind, and placebo-controlled
Likertscale; Wong-Baker FacesPain RatingScale; McGillPain Questionnaire; ProfileofMood States;Mc CockleSymptom DistressScale
Comparepain, nausea,andmood betweenTPVBand GAgroups
(1)TPVB:5mL ropivacaineand 1:400,000 epinephrineatT1---T6 level;
(2)GA:lidocaine1% comepinefrina 1:200,000 (3)CBPV
Seroma(2); Lymphedema(2); Surgicalsiteinfection (1);
Horner’ssyndrome (1)
TPVBusewasnot sustainedwith significanceinthis study
Ibarraetal., 2011;Spain
29 14---GA 15---GA+TPVB
--- Randomized VAS; Neurostim-ulationfor TPVB; telephone Interview
Determinethe associationbetween anesthetictechnique, intensityof postoperativepain, andchronicpain development
(1)Balanced anesthesiawith sevoflurane, remifentanil; (2)Balanced anesthesiawith sevoflurane, remifentanil combinedwithTPVB
Group1: (1)Neuropathicpain: 43%;
(2)Phantombreast: 21%;
(3)Myofascialpain: 33%;
SDPM:50% Group2: Neuropathicpain: 6.7%;
Phantombreast:0%; Myofascialpain:43%; SDPM:6.7%
Neuropathicpainwas morefrequentinGA patients,witha greatertendencyto developphantom breastsensation
Bhuvaneswari etal.,2012; India
48 (G1)12; (G2)12; (G3)12; (G4)12
G1:50.7years; G2:49.1years; G3:48.7years; G4:49years
Randomized VRS;NRS;PONV Evaluatethe effectivenessof lowerconcentrations ofbupivacainewith orwithoutfentanylin PVBinpatients undergoingbreast cancersurgery
(G1):0.25% bupiva-caine+bupivacaine 5mgmL−1;
(G2)0.25% bupiva-caine+bupivacaine 5mgmL−1+fentanil
---2mgmL−1;
(G3)0.5% bupiva-caine+bupivacaine 5mgmL−1;
(G4)Saline
Therewereno complications
Resultsshowthat analgesic consumption,pain assessment,and durationofanalgesia werecomparable amongpatients receivingTPVBwith 0.5%bupivacaineand 0.25% bupiva-caine+fentanyl. 0.25% bupiva-caine+epinephrine combinedwith fentanyl(2gmL−1)
providesexcellent postoperative analgesiacomparable to0.5% bupiva-caine+epinephrine, withtheadvantage ofalowertoxicity profilewhenusedfor asinglelevelofTPVB forbreastsurgery
GA,generalanesthesia;BIS,bispectralindex;TPVB,thoracicparavertebralblockade;CPVB,continuouscatheter---paravertebral
block-ade;VAS,Visual AnalogScale; MPVB,multipleinjections--- paravertebral blockade;mcg, micrograms; NRS,numericscale; OAA/S,
Observer’sAssessmentofAlertnessandSedation;POMS,ProfileofMoodStates;NO,nitricoxide;PO,postoperative;PONV,postoperative
nauseaandvomiting;PPVC,positivepressurecontrolledvolume;SPVB,singleinjection---paravertebralblockade.
feasibility of TPVB in order to reduce pain after breast surgery.18 In the analysis of the included studies, we
observeconsiderableevidencethatTPVBfollowedwithGA provided better PO analgesia with little adverse effects comparedwithother analgesic treatment strategies. This
Byanalyzing thepresent review data,itis perceived that there wasvariation in the concentration of drugs, in the combination with different adjuvants, and in local anes-theticsadministeredintoparavertebralspace.Acontrolled study,whichassessed0.5%ropivacaineversus0.5% bupiva-cainein70womenundergoingmodifiedradicalmastectomy, showedthatthefirstoffersafaster,broaderandlasting sen-soryblockthanthesecond,buttheanalgesicefficacyofboth localanestheticwasequipotent.19
Postoperativechronicpain,includingparesthesia, inter-costobrachial neuralgia, and phantom breast pain affect 25---50% of thepatients after breastcancer surgery.20 The
predictive risk factors for the onset of persistent neuro-pathic pain after this type of surgery are the adjuvant radiotherapyandchemotherapy,painpriortosurgery,type of surgery,nervedamage ---intercostobrachialnerve, psy-chosocialfactors,anxiety,depression,andyoungwomen.20
Amoderatedecrease21wasseenintheaforementioned
stud-iesinpostoperativechronicpainbetween6and12months inpatientswhoreceivedGAwithTPVBcomparedwithGA alone.However,itmustbeanalyzedwithcautionduetothe limitednumberofincludedtrialsandheterogeneity. There-fore,thereisneedtodevelopfurtherstudiestoinvestigate the possible preventive role of TPVB in the incidence of chronicpostoperativepaininpatientswhounderwentbreast surgery.
Thesurgicaltissuedamagealsoresultsinspinal sensitiza-tion;forexample,metabolicactivationandhypersensitivity ofthespinalcordnociceptiveneurons,expansionofsensory receptivefields,andchangesinprocessinginnocuous stim-uli.Thesepostoperativeneuroplasticchangesunderliethe developmentof‘‘pathological’’pain,whichischaracterized bothbyhyperalgesia(primaryorsecondary)andallodynia.21
Thus, an effective analgesia before thenociceptive stim-ulus could reduce the risk of chronic postoperative pain syndrome.
Thepainexperiencedduringmovementwaslowerwhen COX-2inhibitorswerenotadministeredandnone ofthese patientsdevelopedmammarypainsyndromeaftersurgery. The evidence suggests a substantial increase in the lev-elsofCOX-Einthespinal cordafterperipheral damage.22
COX-2inhibition,ifappliedimmediatelyaftersurgery,can helpreducetheprostanoidsproductionandactonneuronal changesthatmaycontributetothedevelopmentofchronic pain.12,22
Nitricoxide(NO)isrelatedtoboththedevelopmentand maintenanceofhyperalgesia.23Threeoptionalmechanisms
havebeenproposedtoexplainthenociceptorsensitization inducedbyNO:(1)NOmayincreasethereleaseofanalgesic substance,suchasprostaglandinE2;(2)NOmayinhibitthe actionofanendogenousantinociceptivesubstancethatacts on peripheral nociceptors; or (3) NOmay act directly on nociceptors.24,25 Inaddition,pharmacological studies
indi-catethatcentralsensitizationisatleastpartiallymediated bytheactivationofN-methyl-d-aspartatereceptors,which
couldlead, ultimately, totheproduction of NO,although thelinkbetween thelocaland systemicproductionis not defined.TheperioperativeprofileofNOafterbreastsurgery wassimilartootherprofilesindifferenttypesofsurgeries (18),withamarkeddecrease12haftertheoperation.12The
factthatnootherdifferencebetweengroupswasdetected canbeattributedtothesmallnumberofpatientspergroup.
Aretrospectiveanalysisof129patientsundergoing mas-tectomyandaxillarydissectionshowedalowriskofcancer
recurrence in those who received TPVB with GA
com-paredwiththosewhoreceivedGAalone.Relevantevidence indicatesthatthesurgical procedure,which releases can-cercellsdirectlyintothecirculation; volatileanesthetics, whichweakenimmunity;postoperativeuseofopioids; pro-angiogenicfactors; andpain itselfareall associated with cancerrecurrence.25 Studieshavereportedareducedneed
fortheuseof postoperativemorphineinpatientsofTPVB group,26 indicating a potential pathophysiological
mecha-nismforalowerrecurrenceofbreastcancer.Addedtothese factorsisthehypothesisthatsomelocalmolecular mecha-nisminperipheralnervesmayberesponsibleforincreasing thedurationqualityofthelocalanestheticblockandpain controlafteradditionofopioids.However,thisresultshould beanalyzedwithcaution,27---30duetothelimitednumberof
includedstudiesandsignificantheterogeneity.
The results of this review are limited because of the clinical heterogeneity of the included studies. First,pain levelswerecalculatedbothbyVisualAnalogScale(VAS)and numericalratingscale (NRS).Onlythreestudiesexplicitly detailedpainduringrestandarmmovement(flexion, abduc-tion, external and internal rotations). Second, the pain scoresdependontheextentofbreastsurgery.Thisindicates thatlessinvasiveoperations,suchassegmentintersections, producedlowerlevelsofpainthanmastectomywithaxillary dissection.Third, the typeof local anesthetics and adju-vants,includingclonidineoropioids,variedamongstudies, whichmayhaveinfluencedtheassessmentofpainseverity. However,thereisevidencethatropivacaine,bupivacaine, levobupivacaine, and lidocaine provide similar analgesia and the administration of adjuvants did not improve the analgesicefficacy.Nevertheless,dataarelacking concern-ingtheproper dosage oflocal anestheticusedin TPVBin breastsurgery. Fourth,thedifferenttechniquesfor estab-lishing paravertebral blockade (SPVB, MPVB, and TPVB ---singleinjectionparavertebralblockade,multipleinjections paravertebral blockade, thoracic paravertebral blockade, respectively)mayplayanimportantroleintheefficacyof analgesia.Wefoundatrendtowardmoreprolonged analge-sia after the combination of GA and TPVB, which in turn generated a reduced need for opioid consumption, as it reducedthealgesicsensation.
Conclusion
Thereisanumberofevidenceonthebenefitsofferedbythe combinationofTPVBandGAinadequatecontrolof postop-erativepain,lowerconsumptionofopioids,andfewadverse effects(nausea,vomiting,pleuralpuncture,pneumothorax) comparedwithother treatment regimens withanalgesics. However,theseresults arelimitedbyclinical heterogene-ityduetotheapplicationofdifferentprocedures(surgical, anestheticandanalgesicdoses).Furtherstudiesareneeded todeterminethebenefitsofthetechnique.
Conflicts
of
interest
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