Rev. bras. ortop. vol.50 número1

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w w w . r b o . o r g . b r

Original

article

Immediate

postoperative

pain

level

from

lumbar

arthrodesis

following

epidural

infiltration

of

morphine

sulfate

夽

Carlos

Alexandre

Botelho

do

Amaral

∗

_,

_Tertuliano

_Vieira,

_Edgar

_Taira

_Nakagawa,

Eduardo

Aires

Losch,

Pedro

José

Labronici

Prof.Dr.DonatoD’ÂngeloOrthopedicsandTraumatologyService,HospitalSantaTeresa,Petrópolis,RJ,Brazil

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Articlehistory:

Received15December2013 Accepted24February2014 Availableonline19February2015

Keywords:

Morphine Epiduralanalgesia Postoperativepain Arthrodesis Vertebralfusion

a

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Objective:Toevaluatethepainlevelinpatientstreatedwithepiduralinfusionofmorphine sulfateinasingledose,afterasurgicalproceduretoperformlumberarthrodesis.

Methods:Fortypatientsunderwentposterolaterallumbararthrodesisorintersomatic lum-bararthrodesisviaaposteriorrouteatone,twoorthreelevels.Theywereprospectively randomizedintotwogroupsof20.Inthefirstgroup(studygroup),2mgofmorphine sul-fatedilutedin10mLofphysiologicalserumwasinfiltratedintotheepiduralspace,through thelaminectomyarea.Thesecondgroup(controls)didnotreceiveanalgesia.Thepatients wereaskedabouttheirpainlevelsbeforeandaftertheoperation,usingavisualanalogscale (VAS).

Results:Itwasfoundthatthepatientspresentedasignificantdiminutionofpainasshown bytheVAS.Frombeforetoaftertheoperation,itdecreasedbyanaverageof4.7points (p=0.0001),whichcorrespondedto53.2%(p=0.0001).

Conclusion:Applicationof2mgofmorphinesulfateinasingleepiduraldosewasshownto beagoodtechniqueforpaintherapyfollowinglumbarspinalsurgery.

Nível

de

dor

no

pós-operatório

imediato

de

artrodese

lombar

após

infiltrac¸ão

epidural

com

sulfato

de

morfina

Palavras-chave:

Morfina

Analgesiaepidural Dorpós-operatória

r

e

s

u

m

o

Objetivo:avaliaroníveldedorempacientestratadoscominfusãoepiduraldesulfatode morfinaemDoseúnica,apósprocedimentocirúrgicodeartrodeselombar.

Métodos:Foramsubmetidosàartrodeselombarposterolateralouartrodeselombar inter-somáticaporviaposterior,emum,doisoutrêsníveis,40pacientes,divididos,prospectivos

夽

WorkdevelopedattheProf.Dr.DonatoD’ÂngeloOrthopedicsandTraumatologyService,HospitalSantaTeresa,andinthePetrópolis SchoolofMedicine,Petrópolis,RJ,Brazil.

∗ _{Corresponding}_author_.

E-mail:carlosaba@oi.com.br(C.A.B.Amaral). http://dx.doi.org/10.1016/j.rboe.2015.02.005

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Artrodese Fusãovertebral

erandomizadosemdoisgruposde20.Noprimeirogrupo(deestudo)foraminfiltradosno espac¸oepidural,atravésdaáreadalaminectomia,2mgdesulfatodemorfinadiluídosem 10mLdesorofisiológico.Osegundogrupo(controle)nãorecebeuanalgesia.Ospacientes foraminterrogadosquantoaoníveldedor,nopréepós-operatório,comousodaescala visualanalógica(EVA).

Resultados: Verificou-sequeospacientesapresentaramumaquedasignificativadadorpela EVA.Adorentreopréeopós-operatóriodiminuiuemmédia4,7pontos(p=0,0001),oque correspondea53,2%(p=0,0001).

Conclusão: Aplicac¸ãode2mgdesulfatodemorfina,emdoseúnicaepidural,demonstrou serumaboatécnicanaterapiadadorapóscirurgianacolunalombar.

Introduction

Despiteadvancesin thetreatments forpostoperativepain, alarge number ofpatients stillsuffer after spinalsurgery. Mostofthesesurgicalprocedurescauseintensepainduring theimmediatepostoperativeperiod,andthismaylastforat leastthreedays.1–5_This_pain_may_increase_morbidity_and_the incidenceofcomplications,alongwithdelayingrehabilitation. Furthermore,postoperativepainisariskfactor,giventhatit maygiverisetodevelopmentofchronicpainsyndromes.6

Safe and efficient methods for postoperative analgesia arethereforeessentialfollowingvertebralarthrodesis proce-dures.Parenterallyadministeredopioidsaremostfrequently indicatedforanalgesiaamongpatientswhohaveundergone lumbararthrodesisbymeansofaposteriorroute.7_Epidural analgesiahasbeenusedinsomeproceduresinthelumbar spine,suchasvertebralarthrodesis,laminectomy,discectomy, hemilaminectomyandforaminectomy.8–10_However, adminis-trationofopioidsintravenouslyorintramuscularlyisgenerally doneatdosesthatmaycausesideeffects,suchasrespiratory depression,nausea,vomiting,sedation,urineretention, pru-ritusandparalyticileus.7_Other_possible_causes_of_pain_may includethepatient’spositioningovertheperioperativeperiod; prolongedanesthesia;longposteriorsurgicalincisions,which giverisetodiscomfortinthepostoperativepositionofdorsal decubitus;largedetachmentoftheparavertebralmusculature, whichisnecessaryforsurgicalaccess;andlongperiodsofuse ofsurgicalretractors.7_Since_the_dural_sac_is_dissected_during thisprocedure,morphinecaneasilyandsafelybeinjectedinto theepiduralregion,bythesurgeonduringtheprocedure.8,10–16 Thisrandomizedprospectivestudyhadtheobjectivesof comparingpatientswhounderwentposteriorarthrodesisof thelumbarspinewithuntreatedpatientsandascertainingthe efficacyofasingledoseofepiduralmorphinesulfateduring theimmediatepostoperativeperiod.

Methods

BetweenJune2008andJanuary2010,40patientswho under-wentintersomaticlumbararthrodesisvia aposteriorroute inone,twoor threelevels were evaluated.These patients, whohaddiagnosesofdegenerativediskdiseaseorstenosisof

thelumbarspinalcanal,wereoperatedundergeneral anes-thesiaatHospitalSantaTeresa,Petrópolis.Approvalforthis study wasobtainedfrom theinstitution’sethicscommittee and informed consentwas obtained from all the patients. Patientswereexcludediftheypresentedthefollowing crite-ria:ASA>III_,_allergy _or_intolerance_to_morphine,_pregnancy,

previousopioiduse,preoperativepainotherthaninthe lum-barspineorpreviouslumbarspinesurgery.Afterthesurgical procedure,patientsinGroup1(studygroup)underwentinsitu epiduralinfiltrationthroughthelaminectomyarea,consisting of2mgofmorphinesulfatedilutedin10mLof0.9% physio-logicalserum.Group2(controls)didnotundergoinfiltration. Bothgroupswereevaluatedregardingpainlevels24hbefore thesurgicalprocedureand18–24hafterthesurgery,bymeans ofavisualanalogscale(VAS).Thisscaleformedaninstrument formeasuringtheevolutionofthepainlevels(Table1).

Statistical

methodology

Thedataobservedwereanalyzeddescriptivelyandpresented intheformofatableshowingfrequencies(n)andpercentages (%)forthecategoricaldataandthemean±standarddeviation andmediansforthenumericaldata.

The statistical analysis was composed of the following methods:

• Toascertainwhethertherewereanysignificantdifferences inthenumericalvariablesbetweenthetwogroups(study andcontrol),Student’sttestforindependentsamplesor theMann–Whitneytestwasusedfornonparametric vari-ables,andtheChi-squaretest(2₎_was_used_for_comparing categoricaldata(qualitativevariables).

• Toanalyzethechangeinthepainscalefrombeforetoafter theoperation,theWilcoxonsignedranktestwasused (non-parametricvariables).

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Table1–Generaldescriptionofthebaselinenumerical variables.

Variable Study

group (n=20)

Control group (n=20)

Femalesex,n(%) 12(60.0%) 11(55.0%)

Malesex,n(%) 8(40.0%) 9(45.0%)

Diskhernia,n(%) 10(50.0%) 11(55.0%)

Vertebralcanalstenosis,n(%) 10(50.0%) 9(45%)

Age(years) 52.1±11.2 51.1±13.7

Source:HospitalSantaTeresa,Petrópolis,RJ.

statistical software, version 6.11 (SAS Institute, Inc., Cary, NorthCarolina,USA).

Results

Thefirstobjectivewastoascertainwhethertherewasany sig-nificantdifferenceinthebaselinevariablesbetweenthetwo groups(studyandcontrol).

Table 2 presents the frequencies (n) and percentages (%) relating to sex and pathological condition, and the mean±standard deviation relating to age and the corre-spondingdescriptivelevel(p-value)ofthestatisticaltest.The statisticalanalysiswascomposedofthe2testforcategorical data(sexandpathologicalcondition)andStudent’sttestfor independentsamples(age).

Itwasobservedthattherewerenosignificantdifferences inthebaselinevariablesbetweenthetwogroups,atthe5% level.

Thesecondobjectivewastoascertainwhethertherewas anysignificantchangeonthepainscalefrombeforetoafter theoperation. Tables3and 4presentthe means,standard deviations(SD) and medianson the pain scale before and aftertheoperation,thecorrespondingabsolutedelta(points) andrelativedelta(%)andthedescriptivelevel(pvalue)ofthe Wilcoxontest,separatelyforthestudygroup(insitu infiltra-tionwithmorphinesulfate)andcontrolgroup,respectively.

Theabsolutedeltaofthepainscalefrombeforetoafterthe treatmentwasgivenbytheformula:

Delta(points)=(preoperativepain−postoperativepain)

Table2–Baselinevariablesaccordingtothegroup.

Variable Study(n=20) Control(n=20) pValuea

Femalesex,n(%) 12(60%) 11(55%) 0.74 Pathological

conditionof diskhernia,n

(%)

10(50%) 11(55%) 0.75

Age(years) 52.1±11.2 51.1±13.7 0.79

Source:HospitalSantaTeresa,Petrópolis,RJ.

Thepathologicalconditionofdiskherniawascomparedwith steno-sisofthevertebralcanal(arthrosis).

a _Descriptive_level_of_the2_or_{Mann–Whitney}_test.

Table3–Preoperativeandpostoperativepainscalesin thestudygroup(n=20).

Variable Mean SD Median pValuea

Preoperativepainscale(points) 8.8 0.9 9 Postoperativepainscale(points) 4.1 1.4 4

Absolutedelta(points) −4.7 1.6 −4 0.0001 Relativedelta(%) −53.2 15.6 −50.0 0.0001

SD,standarddeviation. a _Wilcoxon_signed_rank_test.

Therelativedeltaofthepainscalefrombeforetoafterthe treatmentwasgivenbytheformula:

Delta(points)=(preoperativepain−postoperativepain)

/preoperativepain×100

Itwasfoundthatinthestudygroup,therewasasignificant declineonthe painscale aftertheoperation,comprisinga meanof4.7points(p=0.0001),whichcorrespondedto53.2% (p=0.0001).

Itwasfoundthatinthecontrolgroup,therewasa signifi-cantdeclineonthepainscaleaftertheoperation,comprising ameanof2.7points(p=0.0001),whichcorrespondedto28.8% (p=0.0001).

Thethirdobjectivewastoascertainwhethertherewasany significantdifferenceonthepainscaleandintherespective deltas(absoluteandrelative)betweenthestudyandcontrol groups.

Table5presentsthemeans,standarddeviations(SD)and mediansofthepainscaleandtherespectivedeltas(absolute andrelative)accordingtothegroup(studyorcontrol)andthe correspondingdescriptivelevel(pvalue)oftheMann–Whitney test.

Itwasfoundthatthepostoperativedeclinesforthestudy group were significantly greater than those of the control group; sucha relative declinewas approximately twiceas much,withregardtothepainscale(p=0.0001),absolutedelta (p=0.0001)andrelativedelta(p=0.0001).

Therewasnosignificantdifferencebetweenthetwogroups on the pain scale before the operation, at the 5% level (p=0.086).

Table4–Preoperativeandpostoperativepainscalesin thecontrolgroup(n=20).

Variable Mean SD Median pValuea

Preoperativepainscale(points) 9.3 0.7 9 Postoperativepainscale(points) 6.6 1.2 7

Absolutedelta(points) −2.7 0.9 −2.8 0.0001 Relativedelta(%) −28.8 9.7 −29.7 0.0001

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Table5–Painscaleandrespectivedeltasaccordingtothegroups.

Variable Study(n=20) Control(n=20) pValuea

Mean±SD Median Mean±SD Median

Preoperativepainscale(points) 8.8±0.9 9 9.3±0.7 9 0.086 Postoperativepainscale(points) 4.1±1.4 4 6.6±1.2 7 0.0001 Absolutedelta(points) −4.7±1.6 −4.0 −2.7±0.90 −2.8 0.0001 Relativedelta(%) −53.2±15.6 −50 −28.8±9.7 −29.7 0.0001

SD,standarddeviation.

a _Descriptive_level_of_the_{Mann–Whitney}_test.

Discussion

Perioperative analgesia remains a great challenge for sur-geons,intreatingpatientsthroughcomplexspinalsurgery.17 Since the discovery of opioid receptors in the spinal cord in1970,many studies haveproventhe efficacy ofepidural morphine.18–20 _Surgery_on_the _posterior_region_of_the_spine mayleadtointensepostoperativepainbecauseofthe exten-sive dissection of soft tissues and the detachment of the paravertebralmusculaturetoobtainadequateexposureofthe lamina,facetsandtransverseprocesses.17,21–23

O’Neilletal.8_observed_that_there_was_a_significant reduc-tionintheneedforadditionalanalgesicamongpatientswho underwentlumbarspinalproceduresafter1mgofepidural morphine had been administered. However, these authors warned about side effects. Blacklock et al.12 _studied _five patientswhounderwentlumbarsurgeryafterreceiving1mg ofmorphineepidurally,incomparisonwithacontrolgroup. Althoughtheauthorsobservedthattherewassuperior anal-gesia in the study group over the first 24h, they reported thattherewasareboundeffectwithintensepain,suchthat treatmentwithopioidswasrequiredbetween twoandfive days after the operation. The authors concluded that the pain mighthave been triggered byearly movement ofthe patientorthroughreductioninendorphinproduction.France etal.13_used_a_mean_epidural_morphine_dose_of_0.91_mg_(range: 0.4–1.2mg).Thepatientshadahighlevelofanalgesiaoverthe first24hafterthesurgery,withsignificantlyloweruseof anal-gesicsthan whatwas observedinthe placebogroup.They alsoreportedthattherewasareboundeffectafterthe sec-ondpostoperativeday.Urbanetal.15_analyzed_the_use_of_two morphinedoses(0.7and1.4mg)incomparisonwithacontrol groupthatdidnotreceiveepiduralinfiltration.Bothgroups presentedsuperioranalgesiainrelationtothecontrolgroup. Theseauthorsconcludedthatthebestresultswereobtained amongpatientstreatedwithhighdosesofmorphine(1.4mg). Techanivateetal.16 _conducted_a_{placebo-controlled} ran-domized prospective study involving 40 patients who underwentlumbarlaminectomyandfusion. Theyobserved thatthegrouptreatedwithmorphinepresentedsignificantly lowerpainoverthefirst48haftertheoperation,accordingto theVASscoring,thanwhatwasobservedintheplacebogroup. Wuetal.24_demonstrated_that_low_morphine_doses₍₁_mg) administered epidurally were sufficient for controlling the painafterdecompressionsurgeryandposteriorfusionofthe shortsegmentofthespine.Theseauthorsobservedthatlow

dosesresultedinfewersideeffectsthanwereseenwith intra-venousinjectionofanalgesiacontrolledbythepatient,orwith injectionofmeperidine.

Our study demonstrated that the two groups did not presentanysignificantdifference(p=0.086)inrelationto pre-operativepain,accordingtotheVASscoring.Thisindicates thatthepatientsinthetwogroupshadsimilarintensitiesof pain.However,afterthestudygrouphadbeentreatedwithan applicationof2mgofmorphinesulfateintheperiduralregion, itwasseenaftertheendofthesurgicalprocedurethatthepain levelinthis groupwassignificantlylower,accordingtothe VASscoring.Frombeforetoaftertheoperation,thepainlevel decreasedbyameanof4.7points(p=0.0001),corresponding to53.2%(p=0.0001),inthestudy.Asshownbytheresults,both groupspresentedsignificantdeclinesinpainafterthe treat-ment,butinadifferentiatedmanner,i.e.thegrouptreated withmorphinesulfateshowedasubstantialimprovementin relationtotheuntreatedgroup.

Thepositiveaspectofthisstudywasthatitdemonstrated theefficacyofusingmorphinesulfate,administeredinasingle dose,tosignificantlyreducethepainduringtheimmediate postoperativeperiod.Webelievethatthenegativeaspectof thisstudywasthelackoffollow-upontheevolutionofthe painandanysideeffectsthatmighthaveoccurred.

Conclusion

Applicationof2mgofmorphinesulfateinasingledosewith epiduralinfiltrationwasshowntobeagoodtechniqueforpain therapyfollowingposteriorarthrodesisofthelumbarspine. Thisresultedinhighsatisfactionamongthepatients.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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