REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
OfficialPublicationoftheBrazilianSocietyofAnesthesiology www.sba.com.brSCIENTIFIC
ARTICLE
Does
ultrasonographic
volume
of
the
thyroid
gland
correlate
with
difficult
intubation?
An
observational
study
夽
Basak
Ceyda
Meco
a,∗,
Zekeriyya
Alanoglu
a,
Ali
Abbas
Yilmaz
a,
Cumhur
Basaran
a,
Neslihan
Alkis
a,
Seher
Demirer
b,
Handan
Cuhruk
aaDepartmentofAnesthesiologyandICM,AnkaraUniversityFacultyofMedicine,Ankara,Turkey bDepartmentofGeneralSurgery,AnkaraUniversityFacultyofMedicine,Ankara,Turkey
Received15May2014;accepted17June2014 Availableonline16October2014
KEYWORDS
Ultrasonography; Airwaymanagement; Thyroidgland
Abstract
Backgroundandobjectives: Preoperativeultrasonographicevaluationofthethyroidglanddone bysurgeonscouldletusforeseeairwaymanagementchallenges.Theaimofthisobservational study wasto evaluatetheeffectsofthyroid-relatedparameters assessedpreoperatively by surgeonsviaultrasonographyandchestX-rayonintubationconditions.
Methods:Fiftypatientsundergoingthyroidsurgerywereenrolled.Thyromentaldistance, Mal-lampatiscore,neckcircumferenceandrangeofneckmovementwere evaluatedbeforethe operation.Thyroidvolume,signsofinvasionorcompressionandtrachealdeviationonchest X-raywerealsonoted.TheintubationconditionswereassessedwithCormackandLehanescore andtheintubationdifficultyscale.StatisticalanalysesweredonewithSPSS15.0software.
Results:Themeanthyroidvolumeofthepatientswas26.38±14mL.Themedianintubation difficultyscalewas1(0---2).Thyromentaldistance(p=0.011;r=0.36;95%CI0.582---0.088), Mal-lampatiscore(p=0.041;r=0.29;95%CI0.013---0.526),compressionorinvasionsigns(p=0.041;
r=0.28;95%CI0.006---0.521)andtrachealdeviationonchestX-ray(p=0.041;r=0.52;95%CI 0.268---0.702)werecorrelatedwithintubationdifficultyscale.Alsopatientswereclassifiedinto two groups related totheir intubation difficultyscale (GroupI, n=19: intubationdifficulty scale=0; Group II, n=31: 1<intubation difficulty scale≤5) anddifficult intubation predic-torsandthyroid-relatedparameterswerecompared.OnlyMallampatiscorewassignificantly differentbetweengroups(p=0.025).
夽 Thisstudywaspresentedat44thNationalCongressofTurkishAnesthesiologyandReanimationAssociation,TARK2010,Antalya,Turkey. ∗Correspondingauthor.
E-mail:basakceyda@hotmail.com(B.C.Meco).
http://dx.doi.org/10.1016/j.bjane.2014.06.004
Conclusion: Thethyroidvolume isnotassociatedwith difficultintubation. Howeverclinical assessmentparametersmaypredictdifficultintubation.
© 2014SociedadeBrasileirade Anestesiologia.Publishedby ElsevierEditoraLtda.Allrights reserved.
PALAVRAS-CHAVE
Ultrassonografia; Manejodasvias aéreas;
Glândulatireoide
Existecorrelac¸ãoentreovolumeultrassonográficodaglândulatireóideeintubac¸ão difícil?Umestudoobservacional
Resumo
Justificativaeobjetivos: A avaliac¸ão ultrassonográfica pré-operatória da glândula tireóide feitaporcirurgiõespodepreverdesafiosnomanejodasviasaéreas.Oobjetivodesteestudo observacional foiavaliaros efeitosde parâmetrosrelacionadosàtireoide investigados pré-operatoriamenteporcirurgiõesmedianteultrassonografiaeradiografiadetóraxemcondic¸ões deintubac¸ão.
Métodos: Cinquentapacientessubmetidosàcirurgiadetireoideforaminscritos.Distância tireo-mentoniana(DTM),escoredeMallampati,circunferênciadopescoc¸oeamplitudedemovimento dopescoc¸oforamavaliadosantesdaoperac¸ão.Volumedatireoide,sinaisdeinvasãoou com-pressãoedesviodatraqueianaradiografiadetóraxtambémforamregistrados.Ascondic¸ões deintubac¸ãoforamavaliadascomoescoredeCormackeLehane(CL)eaescaladeintubac¸ão difícil(EID).AnálisesestatísticasforamrealizadascomosoftwareSPSS15.0.
Resultados: Amédiadovolumedatiroidedospacientesfoide26,38±14mL.Amediana da EIDfoi1(0-2).DTM(p=0,011;r=0,36,IC95%0,582-0,088);escoredeMallampati(p=0,041; r=0,29,IC95%013-0,526);sinaisdecompressãoouinvasão(p=0,041;r=0,28;IC95% 0,006-0,521) edesvio datraqueianaradiografia detórax (p=0,041; r=0,52,IC 95%0,268-0,702) foramcorrelacionados comaEID.Ospacientesforamclassificados em doisgrupos também relacionadosàEID (GrupoI,n=19: EID=0;Grupo II,n=31:1<EID≤5),eos preditivosde intubac¸ãodifícileosparâmetrosdatiroiderelacionadosforamcomparados.Apenasoescore deMallampatifoisignificativamentediferenteentreosgrupos(p=0,025).
Conclusão:Ovolumedatireoidenãoestáassociadoàintubac¸ãodifícil.Contudo,osparâmetros deavaliac¸ãoclínicapodempreverintubac¸ãodifícil.
©2014SociedadeBrasileira deAnestesiologia.PublicadoporElsevierEditoraLtda.Todosos direitosreservados.
Introduction
Airwaymanagementisoneofthemostimportantfirst con-cern in the operatingroom not only for anesthesiologists but also for surgeons who are going to operate close to the airway, as failedintubation is associated withsevere morbidityandmortality.Preoperativeevaluationofthe air-way by physicians withobjective parametersis therefore essentialinallcases.Thyroidsurgeryisacommonsurgical procedureoftheneckregionandanenlargedthyroidgland couldyieldariskfactorfordifficult airwaymanagement.1
Howeverroutinephysicalexaminationfailstopredictactual sizeoftheenlargedthyroidgland.Ontheotherhand ultra-sound provides relatively more accurate size estimation andpatientswhowillundergoathyroidectomyarealmost alwayspreoperativelyexaminedbyultrasonographyofthe thyroidglandandchestX-raybytheirrespectivesurgeons. Thus, at the time of preoperative evaluation for thyroid surgeryresultsoftheseexaminationsarealreadyavailable foralmostevery patient.Consideringthis,someobjective data from these alreadyobtained preoperative investiga-tions couldalsobeusedbythe interdisciplinaryphysician
teamfor thepreoperative riskcalculation of difficult air-waysamongthisgroupofpatients.
Astheultrasonographicvolumeof theenlargedthyroid glandanditsimpactontheairwaymanagementisstillnot trulyappraised,theprimaryaimofthisstudywasto eval-uatetheimpactofthethyroidglandvolumeestimatedby ultrasonographyontheendotrachealintubationconditions. Nearby,thesecondaryaimwastocorrelatethese parame-terswithclassicalindicatorslikeMallampati classification, thyromentaldistance(TMD),neckcircumferenceand move-mentsforpredictingdifficultendotrachealintubation.
Methods
younger then 18 and older then 75 were excluded from the study. Preoperative airway assessment consisting of TMD (>70mm or <70mm), Mallampati classification, Cor-mack and Lehane (CML) score, range of neck movement (>80◦ or <80◦)andneck circumference(>43cmor <43cm) was performed by an attending anesthesiologist. Thyroid volume,signsofinvasionorcompressionandtracheal devi-ationonchest X-ray werenoted.Detection ofdysphonia, changeinvoicequality,dyspnea,stridor,hoarsenessand/or cough during the preoperative evaluation was considered assignsofinvasionorcompression. Thyroidvolumeswere calculatedvia ultrasonographicmeasurement.The volume ofeachthyroidlobewascalculatedwithellipsoidformula (height×width×depth×0.524)andthetotalvolumeofthe thyroidwasobtainedasthesumoftwothyroidlobes.2Direct
X-ray examination of the neck and chest were also done toassessthe trachealdeviation definedas1cmdeviation of trachea from the midline. Additionally histopathologi-caldiagnosisofeachpatientwasrecordedasmalignantor benigndisease.
All patients were premedicated with intravenous (iv) midazolam(0.01mg/kg). TheASA monitoringconsistingof noninvasivebloodpressure,pulseoximetry, electrocardio-gram, and measurement of end-tidal carbon dioxide was done. Dexketoprofen trometamol 50mg iv was given for postoperativepainmedicine.Anesthesiawasinduced with lidocaine(1mg/kg)andpropofol(3mg/kg).Tracheal intuba-tionwasfacilitatedbytheadministrationofivrocuronium (0.6mg/kg). Patientwereintubated90safter rocuronium administrationbyacertifiedanesthesiologistwitha Macin-toshlaryngoscope(Blade3or4)andthelaryngealviewwas assessedaccordingtotheCormackLehaneScore(CMS) grad-ingsystemdefinedas:grade1=completevisualizationofthe vocal cords; grade 2=visualization of the inferior portion oftheglottis;grade3=visualizationofonlytheepiglottis; andgrade4=novisualizedepiglottis.3Intubationdifficulty
wasassessedusingtheintubationdifficultyscale(IDS).The IDSisacombinationofsevencriteriathathavebeen asso-ciatedwith difficult intubation: (1) number of intubation attempts;(2)numberofoperators;(3)numberof alterna-tivetechniques;(4)CormackGrademinus1;(5)liftingforce required tomake laryngoscopy;(6) necessity of laryngeal pressure;and(7)positionofvocalcords.Ascoreof0 indi-cateseasyintubation,ascorefrom1to5indicatesaslightly difficultintubation,andascoremorethan5indicates mod-erate to major difficulty.4 The intubation time (the time
intervalbetweenthefirstcontactofthelaryngoscopeand thesuccessfulendotrachealintubationandinflationofthe cuff)wasalsorecorded.Furthermorenumberofintubation attemptswasrecorded.Aftertrachealintubation,the cor-rectpositioningoftheendotrachealtubewasconfirmedby theauscultationofbothhemithorax.Sevoflurane concentra-tionthatadjuststo1MACwith50%nitrousoxideinoxygen wasusedfortheanesthesiamaintenance.
The thyroidectomy wasperformed withpatients inthe supineposition,withtheheadslightlyhyperextended.Side effectsrelatedtointubationsuchasbleeding, sorethroat orhoarsenesswereevaluatedafterextubationandnoted.
Apoweranalysiswasperformedbeforetheinitiationof the study. The results of the previous study of Amathieu etal.wereusedtocalculatethenumberofpatientsneeded to enroll into the study to find a statistically significant
correlation between the enlarged thyroid gland and IDS score.1Accordingtothecalculation50patientswereneeded
tocalculatethecorrelationbetweenthethyroidgland vol-umeandIDSscore.Thestatisticalanalysesweredonewith SPSS 15.0 software (SPSS Inc., Chicago, IL, USA). Demo-graphic data and predictors of difficult intubation were presentedasmean±SDandnumberofpatients.Correlation analysisofIDSwithpredictorsofdifficultintubation(TMD, Mallampati score,compression or invasion signs, tracheal deviationonchestX-ray,neckmobilityandneck circumfer-ence),thyroidglandvolumeanddiagnosisweredonewith Pearson’scorrelationanalysis.Theresultsofthecorrelation analysis were presented asr(correlation coefficient) and
p value withtheconfidence interval.The patient popula-tionwasdividedintotwogroupsaccordingtotheIDSvalue (GroupIn=19;IDS=0andGroupIIn=31;1<IDS≤5). Predic-torsofdifficultintubation,numberofintubationattempts, intubationtimeandthepresenceofcompressionsignswere furtheranalyzedwithStudent’st-test,Mann-WhitneyUtest andChi-square test aswhereindicated, and presentedas mean±SD,medianandquartilesandnumberofpatients.A
pvalueof<0.05wasacceptedassignificant.
Results
Demographicandsurgicaldataofthepatientsarepresented in Table 1. The meanthyroid volume of thepatients was 26.38±14mL.Thenumbersofpatientswhohavepredictors ofdifficultintubation(thyromentaldistance<7cm, Mallam-patiscoreIII---IV,neckmovement<80◦orneckcircumference >43cm)arepresentedinTable2.Sixpatientsoutof50had compressionorinvasionsignsand6hadtrachealdeviation onchestX-ray.In4patients thosefindingswere concomi-tant.Allpatientswereintubatedatthefirstattemptwithout any significant difficulty. The median IDS was1(0---2) and theoverallincidenceofdifficultintubationdefinedasIDS>5 was0%.Thirty-eightpercentoftheintubations(n=19)were performedwithoutdifficulty(IDS=0)while62%(n=31)had minor difficulty (1<IDS≤5). Three patients had IDS of 5. ThemedianandquartilesofCormackandLehanescorewas
Table1 Demographicandsurgicaldata.
Age(year) 47±9
Height(cm) 162±6
Weight(kg) 78±13
Anesthesiatime(min) 143.8±33 Surgerytime(min) 134±36 Diagnosis(malign/benign)(n) 6/44
Dataaremean±SDornumericalvalue.
Table2 Predictorsofdifficultintubation.
Variables Numberofpatients
MallampatiIII---IV 7 Neckmovement<80 26 Neckcircumference>43cm 11 Thyromentaldistance<7cm 1
Table3 CorrelationanalysisofIDSwithpredictorsof dif-ficultintubation.
Variables p-Value r-Value 95%CI
Thyromental distance<7cm
0.011 0.36 0.582---0.088
MallampatiIII---IV 0.041 0.29 0.013---0.526 Compressionor
invasionsigns
0.041 0.28 0.006---0.521
Trachealdeviation onchestX-ray
0.041 0.52 0.268---0.702
Diagnosis
(malign/benign)
0.28 0.15
---Neckmobility<80 0.25 0.17 ---Neck
circumference >43cm
0.21 0.18
---Thyroidgland volume
0.85 −0.03
---CI,confidenceinterval;IDS,intubationdifficultyscale.
2(1---2). The median numberof intubationattempt was1 (1---1)andthemediantimetointubatewas85(48---98)s.
ThecorrelationanalysesofIDSwithpredictorsofdifficult intubation andthyroid volumeare shown in Table3. Fur-thermorenosignificant correlationwasobservedbetween IDS andpostoperativeside effectssuchashoarseness and sorethroatatrestandwithswallowing.
Patientswereclassifiedintotwogroupsrelatedtotheir IDS(GroupI:IDS=0;GroupII:1<IDS≤5).Demographicdata weresimilaramonggroups.Routinepredictorsfordifficult intubationandthyroid-relatedparameterswerecompared betweenthesegroupsandMallampatiscorewassignificantly differentbetweengroups(Table4).
Discussion
The primaryfindings of this study were that IDS was not correlatedwiththyroid-relatedparameterssuchasvolume andmalignancy,butitwascorrelatedwithtracheal devia-tion,compressionsignsandwithroutinedifficultintubation
predictorssuchasTMDandMallampatiscore.Thesecondary findingswerethedifferencebetweenIDSgroupsrelatedto Mallampatiscore.
Amathieu etal., witha verysimilarstudydesign with-outtheultrasonographiccalculationoftheenlargedthyroid gland volume, showed that the presence of a goiter or goiter-associated airway deformities, compressive symp-toms or endothorasic position were not associated with difficultintubation.1 In contrastwiththeseresults, inour
study, tracheal deformity related to thyroid gland and compression signs were correlated with intubation score. When enlarged, the thyroid gland may exert a pressure onthetracheaandadjacenttissuesandthispressuremay deviate the trachea and cause some compression signs. Thesechangesinthetissueanatomymayrenderintubation moredifficult andlower the qualityof the intubation. In concordancetoourstudy,Voyagisetal.demonstratedthat whenthyroidenlargement wasaccompaniedby anairway deformityitconstitutedan aggravatingfactorfor difficult intubation.5
Inanotherstudy,Bouaggadetal.demonstratedthatin 320patientsundergoingthyroidectomythedifficultyof intu-bationwasincreasedonlywithmalignantthyroiddiseases.6
Themechanismfordifficultintubationisexplainedwithan advancestageofthedisease,whichleadstotracheal inva-sion and tissue infiltration. In our study,the presence of thyroid malignancywas not related toan increased intu-bationdifficulty.Thisdiscrepancymaybeexplainedbythe timeofdiagnosis.Allofourpatientswithmalignancywere earlystagediseases.
In our study group only 6 patients had invasion and compression signs and 6 had tracheal deviation on chest X-ray.In 4patients thosefindingswereconcomitant, thus actually 8 patients had them. Additionally and interest-ingly,thediagnosisofallthepatientswithcompressionsigns andtrachealdeviationwasbenign.Alsointhisstudygroup thyroid gland volume was 20.21±13mL in malign group and27.70±15inbenign group.Although statistically non-significant,patientswithbenigndiseaseshadbiggerthyroid glandwhichmayexplaintheincidenceofcompressionsigns andtrachealdeviation.FurthermoreBouaggadetal. mea-sured the size of the thyroid gland in millimeters along the main straight line of the gland and did not find any
Table4 Comparisonofpredictorsandexpressionsfordifficultintubationbetweengroups.
Variables IDS=0(n=19) 1<IDS≤5(n=31) p-Value
Thyromentaldistance<7cm 0 1 NS
Mallampatiscore 1.5±0.6 2±0.6 0.025
MallampatiIII-IV 1 6 NS
CormachandLehanescore 1(1---1) 2(1---4) <0.001
Neckmobility<80 8 16 NS
Neckcircumference>43cm 2 9 NS
Diagnosis(malign/benign) 0/19 6/25 NS
Thyroidglandvolume 27.20±12.21 25.74±16.77 NS
Compressionsigns 2 4 NS
TrachealdeviationonchestX-ray 1 5 NS
Numberofintubationattempt 1(1---1) 1(1---5) 0.026
Intubationtime 81.93±34.55 80.21±38.74 NS
correlationbetweenthyroidsizeandintubationdifficulty.6
Thismeasurementisincorrelationwithourresultsrelated tothevolumetricmeasurementsofthethyroid.
SekerandTashadevaluated251healthyvolunteersand definedthemeanthyroid volumeof Turkishpopulation as 13±6.27mL.7AlsoErbiletal.reportedinapopulationof
402patients,thatthethyroidvolumeinpatientswith thy-roidcarcinomawas38±18mLandinpatientswithbenign diseasesitwas73.3±48mL.8Themeanthyroidvolumeof
our study group was 26.38±14mL, which is higher than thehealthypopulation but stilllowerthan Erbil’sresults. Thesefindings mayexplainthe factthat inour studythis volumedidnothaveanyeffectonintubationcondition. Big-gerthyroidglandmighthavehadsomedifferenteffecton intubationconditions.
Theanalysisofroutinepredictorsofdifficultintubation revealed that more frequently used TMD and Mallampati scorewerecorrelatedwithIDSbutneckcircumferenceand motilitywerenot.Theseresultsarepartlyinconcordance withAmathieu etal.results,whichstated thatusual pre-operativepredictorsfor difficultintubationsuchasmouth opening,Mallampatiscore,TMDandneckmobilitywere reli-ableparametersalsointhyroidsurgerypatients.1
Also,whendividingpatients into2 groupsaccording to theirIDS, therewasonlyasignificant differencebetween Mallampatiscore,whichissimilartothepreviousresultsof thestudy.
Takingintoaccountthatnoneofourpatientswere diffi-culttointubate,itis difficulttocorrelate thyroid-related parameters with difficult intubation. Although this might seem like a limitation in this study, it actually reflects thatin our daily clinical practiceand patientpopulation, thyroid-relatedparametersdonotreally increase therisk of difficult intubationin our setting. Nevertheless, bigger patientseriesareprobablyneededtocometomore compre-hensiveconclusions,especiallytakingmorespecificgroups intoaccountlikemalignantdiseaseorgiantthyroidmasses.
Insuchoccasions,findingsofthethyroidUSGandchestX-ray alreadyorderedpreoperativelybythesurgeonscouldreveal valuableinformationtotheanesthesiologisttoassessbetter riskanalysis.
Inconclusion,thevolumeofthethyroidglandisnot cor-relatedwiththeintubationdifficultyscore.Asthesignsof tracheal deviation onthe chest X-ray andcompression or invasion signs represent a moderate correlation withIDS, specialcareshouldbetakeninpatientswithtracheal devi-ationandcompressionsigns.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
References
1.AmathieuR,SmailN,CatineauJ,et al.Difficultintubationin thyroidsurgery:mythorreality?AnesthAnalg.2006;103:965---8.
2.Shabana W, Peeters E, De Maeseneer M. Measuring thyroid glandvolume: should we changethe correction factor?Am J Roentgenol.2006;186:234---6.
3.MenckeT,EchternachM,KleinschmidtS,etal.Laryngeal morbid-ityandqualityoftrachealintubation:arandomizedcontrolled trial.Anesthesiology.2003;98:1049---56.
4.AdnetF,Borron SW,RacineSX,etal.Theintubationdifficulty scale(IDS):proposalandevaluationofanewscore characteriz-ingthecomplexityofendotrachealintubation.Anesthesiology. 1997;87:1290---7.
5.VoyagisGS, KyriakosKP.The effectofgoiteronendotracheal intubation.AnesthAnalg.1997;84:611---2.
6.BouaggadA,NejmiSE,BouderkaMA,etal.Predictionofdifficult intubationinthyroidsurgery.AnesthAnalg.2004;99:603---6.
7.SekerS,TasI.Determinationofthyroidvolumeanditsrelation withisthmusthickness.EurJGenMed.2010;7:125---9.
