REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
OfficialPublicationoftheBrazilianSocietyofAnesthesiologywww.sba.com.br
SCIENTIFIC
ARTICLE
Predictive
value
of
preoperative
tests
in
estimating
difficult
intubation
in
patients
who
underwent
direct
laryngoscopy
in
ear,
nose,
and
throat
surgery
Osman
Karakus
a,
Cengiz
Kaya
b,∗,
Faik
Emre
Ustun
b,
Ersin
Koksal
b,
Yasemin
Burcu
Ustun
baAnesthesiologyandReanimationDepartment,CorumTrainingandResearchHospital,HititUniversity,Corum,Turkey bAnesthesiologyandReanimationDepartment,Facultyofmedicine,OndokuzMayisUniversity,Samsun,Turkey
Received19February2014;accepted13May2014 Availableonline8June2014
KEYWORDS
Intubation; Endotracheal; Laryngoscopy; Otolaryngology
Abstract
Backgroundandobjectives: Predictivevalueofpreoperativetestsinestimatingdifficult intu-bationmaydifferinthelaryngealpathologies.Patientswhohadundergonedirectlaryngoscopy (DL)werereviewed,andpredictivevalueofpreoperativetestsinestimatingdifficultintubation wasinvestigated.
Methods:Preoperative,andintraoperativeanesthesiarecordforms,andcomputerizedsystem ofthehospitalwerescreened.
Results:A totalof2611patientswereassessed.In7.4%ofthepatients,difficultintubations weredetected.DifficultintubationswereencounteredinsomeofthepatientswithMallampati scoring(MS)systemClass4(50%),Cormack---Lehaneclassification(CLS)Grade4(95.7%), previ-ousknowledgeofdifficultairway(86.2%),restrictedneckmovements(cervicalROM)(75.8%), shortthyromentaldistance(TMD)(81.6%),vocalcordmass(49.5%)asindicatedinparentheses (p<0.0001).MShadalowsensitivity,whilerestrictedcervicalROM,presenceofavocalcord mass,shortthyromentaldistance,andMSeachhadarelativelyhigherpositivepredictivevalue. Incidenceofdifficultintubationsincreased6.159and1.736-foldwitheachlevelofincreasein CLSgradeandMSclass,respectively.Whenalltestswereconsideredincombinationdifficult intubationcouldbeclassifiedaccuratelyin96.3%ofthecases.
Conclusion: TestresultspredictingdifficultintubationsincaseswithDLhadobservedly over-lapped with the results provided in the literature for the patient populations in general. Differencesinsometestresultswhencompared withthoseofthegeneralpopulationmight stemfromtheconcomitantunderlyinglaryngealpathologicalconditionsinpatientpopulations withdifficultintubation.
© 2014SociedadeBrasileirade Anestesiologia.Publishedby ElsevierEditoraLtda.Allrights reserved.
∗Correspondingauthor.
E-mail:raufemre@yahoo.com(C.Kaya).
http://dx.doi.org/10.1016/j.bjane.2014.05.009
PALAVRAS-CHAVE
Intubac¸ão; Endotraqueal; Laringoscopia; Otorrinolaringologia
Valorpreditivodostestespré-operatóriosparaestimaraintubac¸ãodifícilem
pacientessubmetidosàlaringoscopiadiretaparacirurgiadeouvido,narizegarganta
Resumo
Justificativaeobjetivos: Ovalorpreditivodostestespré-operatóriosparaestimaraintubac¸ão difícil pode diferir em patologias laríngeas. Foram feitas uma revisão dos prontuários de pacientes submetidos àlaringoscopia direta (LD) euma investigac¸ão dovalor preditivo de examespré-operatóriosparaestimaraintubac¸ãodifícil.
Métodos: Triagemdeprontuáriosdosperíodospré-operatórioeintraoperatórioedosistema informatizadodohospital.
Resultados: Foramavaliados2.611pacientes.Em7,4%,intubac¸õesdifíceisforamdetectadas. Intubac¸õesdifíceisforamconstatadasempacientescomescoredeMallampati(EM),classe4 (50%);classificac¸ãodeCormack-Lehane(CCL),grau4(95,7%);conhecimentopréviodeviaaérea difícil(86,2%);restric¸ãodaamplitudedemovimentos(ADM)dopescoc¸o(ADMcervical)(75,8%); distânciatireomentoniana(DTM)curta(81,6%);emassanaspregasvocais(849,5%)(p<0,0001). OEMapresentouumasensibilidadebaixa,enquantoADMcervical,presenc¸ademassanas pre-gasvocais,DTMcurtaeEMapresentaramumvalor preditivopositivorelativamentemaior.A incidênciadeintubac¸õesdifíceisaumentou6.159e1.736vezescomcadaníveldeaumentodos grausdaCCLedaclassedoEM,respectivamente.Quandotodosostestesforamconsiderados emconjunto,aintubac¸ãodifícilpôdeserclassificadacomprecisãoem96,3%doscasos.
Conclusão:Osresultadosdostestesquepreveemintubac¸õesdifíceisemcasoscomLD coincidi-ramclaramentecomosresultadosprevistosnaliteraturaparaaspopulac¸õesdepacientesem geral.Asdiferenc¸asemalgunsresultadosdostestes,quandocomparadoscomosdapopulac¸ão emgeral,podemserporcausadascondic¸õespatológicassubjacentesdalaringeempopulac¸ões depacientescomintubac¸ãodifícil.
©2014SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Todosos direitosreservados.
Introduction
Many studies and meta-analyses have examined the pre-dictivevalueofpreoperative testsindeterminingdifficult intubations. As laryngeal abnormalities are observed in directlaryngoscopicinterventionsinear,nose, andthroat surgery, the predictive values of these tests may differ. There appears tobe norelevant studies in the literature inthepatientpopulationwhohadundergonedirect laryn-goscopy.
Directlaryngoscopy(DL)isperformedtoevaluate laryn-gealstructures, includingtheglottis andthe vocal cords, bydirectinspection.Abnormalitiesofthisregionare diag-nosedby examining biopsy specimens priorto performing therapeuticinterventionsifnecessary.
During this procedure, the most fundamental duty of theanesthetististoprovideadequateventilation.The pre-requisite of adequate ventilation is to ensure a safe and patentairway.Preoperativepredictionofapotentially diffi-cultintubationisimportanttomakeproperpreparationsand toplananappropriateintubationtechnique.Inthe preoper-ativeevaluationofdifficultintubation,themouthopening, thestateofthetongueandpalate,thethyromentaldistance (TMD),thesternomentaldistance,thecervicalROMandthe mandibularmobilityareassessed,andevidenceofdifficult intubation(ifany)isinvestigated.InDL,routine preopera-tiveindirectlaryngoscopicexaminationfindingsalsoprovide importantinformation.1,2
Inthisretrospectivestudy,weevaluatedtheanesthesia
recordsofpatients whohad receivedanesthesiabetween
2000and2012becauseofDLtoinvestigatethepredictive
valueofpreoperativetestsindifficultintubation.
Materials
and
methods
Inthisstudy,pre-andintraoperativeanesthesiarecordsof
patientswhohadreceivedanesthesiabecauseofDLinthe
Department of Anesthesiology and Reanimation, Ondokuz
MayisUniversityFacultyofMedicinebetween2000and2012
due toDL wereexamined after obtainingthe approval of
the ethics committee. We previously published
epidemi-ological examination results of anesthetic applications in
patientswhounderwentDLduring2000---2010.Inthecurrent
study,datarelatingto2010---2012werealsoevaluated,and
preoperativepredictivetestresultsrelatedtodifficult intu-bationprocedureswerestatisticallyanalyzedindetail.Data
obtainedfromthemedicalfilesofpatientsinthe
hospital-basedcomputerizedsystemwerescreened.
Thefollowingparameterswereevaluated:
1. AgedistributionofthepatientswhohadDL:0---1,1---5, 5---15,15---45and>65years,
2. Genderdistributionandthenumberofpatientswhohad
DL,
3. Indicationsfor DL.Aspre-2005 dataonDLindications
were not available in the medical files, the
indica-tions for DL performed between 2005 and 2012 were
4. NumbersofcasesofDLevaluatedseparatelyinelective
andemergencysurgicalsettings,
5. AmericanSocietyofAnaesthesiology(ASA)scoresofthe
patientswhounderwentDL,
6. Ratesofadditionalsystemicdiseases,
7. Meananesthesiatimes,
8. Numbers of DL patients who had any of the
follow-ing postoperative complication rates: cardiovascular,
pulmonary, re-intubation, and delayed arousal from
anesthesia,
9. Ratesofdifficultintubation,
10. Genderdistributionofthedifficultintubationcases, 11. Agedistributionofthedifficultintubationcases,
12. NumbersoftheMallampatiscores(MS)oftheintubated
patients,
13. Ratesofdifficultintubationcasesbasedonthe
Mallam-patiscoringclassificationcriteria,
14. Rates of difficult intubation cases based on the
Cormack---Lehanescore(CLS),
15. Ratesof the intubatedcases withdifficult intubation
basedontheCLScriteria,
16. Ratesofintubatedpatientswithahistoryofadifficult airway,
17. Ratesof the intubatedcases withdifficult intubation
basedonthehistoryofadifficultairway,
18. Ratesoftheintubatedpatientsbasedonrestricted
cer-vicalROM,
19. Rates of the difficult intubation cases according to
restrictedcervicalROM,
20. RatesoftheintubatedpatientsaccordingtoTMD
mea-surements,
21. Ratesof the intubatedcases withdifficult intubation
basedonTMDmeasurements,
22. Ratesoftheintubatedpatientsbasedonthepresence
ofavocalcordmass,
23. Ratesofthedifficultintubationcaseswithavocalcord mass,
24. Logisticregression analysis of preoperative indicators
ofdifficultintubation,
25. Predictivevalueofscreeningtestsintheevaluationof difficultintubation.
The sensitivity, specificity, positive predictive values
(PPV)andnegativepredictivevalues(NPV)werecalculated
accordingtothefollowingformula:
Sensitivity
=Number of accurately predicted difficult intubations
Number of difficult intubationsencountered
Specificity= Numberofaccuratelypredictedeasyintubations
Numberofeasyintubationsencountered
PPV=Numberofaccuratelypredicteddifficultintubations
Totalofanticipateddifficultintubations
NPV
= Numberofaccuratelypredictedeasyintubations
Totalnumberofpatientswithunforeseendifficultintubations
Statisticalanalysis
The SPSS 21.0 statistical package program was used for
the data analysis. The data are presented as mean±SD
(standard deviation), frequencies and percentages. For
intergroup comparisons, chi-square and Mann---Whitney U
tests were employed. p<0.05 was considered to be
sig-nificant. To determine the factors involved in difficult
intubation,logisticregressionanalysiswasperformed.
Results
Duringthestudyperiod,atotalof2611patients(females,
n=333; 12.8%; males, n=2278; 87.3%) underwent DL in
theear, nose and throat (ENT) operative room (p<0.05).
The patients were aged 45---65 years (n=1417; 54.3%) or
older than 65 years (n=559; 21.4%) (p<0.05). Table 1
showstheindicationsforthosewhounderwentDLbetween
2005and2012.The patientswereoperatedoninan
elec-tive(n=2.557; 97.9%) or emergency(n=54; 2.1%) setting (p<0.05).TheASAscoresofthepatientswhounderwentDL wereasfollows:ASAI,38.3%;ASAII,46.9%;ASAIII,13.9% andASAIV,0.9%(Fig.1).
Concomitantsystemic diseases were found in 50.4% of
the patients (cardiovascular disease 11.6% and
respira-torysystemdisease11.5%).Themeananesthesiatimewas
35.6±13.6min. Postoperative complicationsaffecting the
respiratory(19.2%)orcardiovascularsystem(72.4%)
devel-opedin268(10.3%)ofthepatients.
Difficult intubation was detected in 194 (7.4%) of the
patients. Twenty-six (7.7%) women and 168 (7.4%) men
couldnotbeintubated.Therewasnostatisticallysignificant
differencebetween the age groups with respect to
diffi-cult intubation (p>0.05).Fiberoptic bronchoscopy(n=5),
surgical tracheotomy with mask ventilation (n=5) and a
fast-tracklaryngeal mask(n=1)wereusedinthepatients
with difficult intubation. The other patients were
intu-batedby experiencedanesthetistsusingastylet,aMcCoy
laryngoscope,adifferentsizelaryngealbladeandassisted
techniques, such as backward-upward-rightward pressure
maneuvers.
Table 1 Indications of direct laryngoscopies performed between2005and2012(n,%).
Indicationsofdirectlaryngoscopy n % Benigndiseasesofthelarynx 427 23% Malignantdiseasesofthelarynx 659 35.6% Congenitaldefectsofthelarynx 14 0.7%
Laryngealinfections 85 4.5%
Tracheal,bronchial,andpulmonary diseases
32 1.7%
Oesophagealdiseases 119 6.4%
Hypopharyngealdiseases 86 4.6% Aspirationofaforeignsubstance 20 1%
Hoarseness 195 11%
Dyspnea 78 4.2%
Other 136 7.3%
50
45
40
35
30
25
20
15
10
5
0
ASA I ASA II ASA III
Patients, (%)
ASA IV
Figure1 ASAscoresofthepatients(%).
Inourstudy,2045patientswereevaluatedusingMS crite-riaandclassifiedasMSI(65.8%),MSII(29.9%),MSIII(3.7%) andMSIV(0.4%)categories(Fig.2).Difficultintubation pro-ceduresweredetectedinpatientsclassifiedinMSI(2.6%),
70
60
50
40
30
20
10
0
MS I MS II MS III
Patients, (%)
MS IV
Figure 2 Mallampati scores of the patients (mallampati scores;MS,%).
Table 2 Logistic regression analysis of the preoperative screeningtestsperformedfordifficultintubation.
Difficultintubation pvalue Oddsratio
Mallampatiscore 0.003 1.736
Cormack---Lehanescore 0.0001 6.159 Historyofdifficultairway 0.011 2.887 RestrictedcervicalROM 0.0001 6.518
Vocalcordmass 0.0001 2.968
MS II (13.2%), MS III (60.5%) and MS IV (50%) categories (p<0.0001).
Ofthestudygroup,1910ofthepatientswerequestioned aboutpastexperienceofadifficultairway.Difficult intuba-tionsoccurredin25(86.2%)ofthe29(1.5%)patientswitha historyofadifficultairway(p<0.0001).Restrictedcervical ROMwasinvestigatedin1913ofthepatientsanddetected in 3.2%(n=62) ofthe cases.Forty-seven (75.8%)of these 62patientshaddifficultintubationprocedures(p<0.0001). TheTMDhadbeenmeasuredin1913ofthepatients.Among these, 49 (2.6%) of the patients had a short TMD, and 40(81.6%) hadahistory ofdifficult intubationprocedures (p<0.0001).Thepresenceofavocalcordmasswasassessed in2588patients.Ofthese,279(10.8%)ofthepatientshad avocalcordmass,andevidenceofdifficultintubationwas presentin138(49.5%)ofthecases(p<0.0001).
Logisticregressionanalysisofthepreoperativescreening testsperformed fordifficult intubationdemonstratedthat anincreaseofonelevelintheCLgradeandtheMallampati classinduced 6.159-foldand1.736-foldincreases, respec-tively, in therate of difficult intubations(Table 2).When allthetestsinTable2areconsideredasawhole,difficult intubationcouldbeaccuratelyclassified(presentorabsent)
in96.3%ofthecases.The predictivevaluesforthe
preop-erative screening tests usedfor the detectionof difficult
intubationsinourpatientsareshowninTable3.
Discussion
The retrieval of medical records of patients in an
orga-nizedfashionisnecessarytoperformdataanalysesandto
prepare monthly and yearly clinical study reports for the
improvement of quality and the provision of health care
services.Themale/femaleratioofourstudypopulationwas
Table3 Predictivevalueofpreoperativescreeningtestsfordifficultintubation.
Screeningtests Screeningtests,(%)
Sensitivity Specificity PPD NPD
Mallampatiscore 30.5 97.9 59.3 93.6
Cormack---Lehanescore 75.3 98 78.6 97.6
Historyofdifficultairway 21.5 99.7 86.2 92.5
RestrictedcervicalROM 28.1 99.1 75.8 92
Shortthyromentaldistance 23.9 99.4 81.6 93.1
nearly1/7(p<0.05),aratiobetween1/5and1/20hasbeen reportedinDLstudies,3,4withDLbeingperformedinallage
groupsbutmostfrequentlyinthoseofadvancedage(>45).
Inthepresentstudy,DLwasalsomostcommoninpatients
aged45---65yearsandolder(p<0.05).
Laryngealcancersconstitute45%ofheadandneck
can-cersand1---2%ofalltypesofcancers.5Inourstudy,themost
frequentlyencounteredindicationsof DLwerebenignand
malignantdiseasesofthelarynx(58.6%).
Thepatientsweremostly(97.9%)scheduledforelective
surgery(p<0.05).Thisfindingisinagreementwiththatof other studies that investigatedthe typeof the surgery.6,7
ASA II patientswere morenumerous in thecurrent study.
Weattribute thisfindingtothemorefrequentapplication
ofDLinadvancedagegroupsandtheincreasingfrequencyof
concomitantdiseaseswithaging.Themeananesthesiatime
was35.6±13.6min. This wasaffectedby variousfactors,
suchasthesurgicalprocedureapplied,theskillandtalents oftheanesthetistandthesurgeonandthegeneralstatusof thepatient.
Cardiac complications are usually the most frequently
encountered problem during the postoperative period
(16---62%).8,9 This was also the case in the current study,
withcardiaccomplicationsseenmorefrequently(7.3%)than
othertypesofproblems.
According toa reportpublishedby the ASA in2013 on
the management of a difficult airway, difficult intubation
is defined as the requirement for recurrent interventions
for intubation in the presence or absence of tracheal
pathology.10Theoverallincidenceofdifficultintubationhas
beenreportedas1---3%inthegeneralpopulation.11,12Inthe
presentstudy,theincidencewas7.4%.Thishigherratemight
stem fromthe presence of laryngeal pathologies in these
cases.Accordingtotheliterature,difficultintubationsare
more frequentlyencountered in malepatients.13,14 In the
currentstudy,difficultintubationprocedureswerefoundin
7.4%ofmalesand7.7%offemalepatients,withoutany
sta-tisticallysignificantdifferencebetweengenders(p>0.05).
Mostaetiological factorsfor difficult intubationcan be
determined with careful preanaesthetic evaluation, and
stepscanbeputinplacetopreventdifficultintubation.To
predictdifficultintubationbeforehand,theTMD,the
ster-nomentaldistanceandtheextensionoftheneckhavebeen
used,aswellastheMSandtheCLS.15---17
Toobtainanticipatedbenefitsfromthetestsused,they
shouldhave highersensitivity specificityand PPV.18,19 The
applicationof thesetestswillallow timefor therequired
preparationsfor potentiallydifficult intubationsandavoid
unnecessarypreparationsforeasyintubations.
Similartoourstudy,aretrospectivestudythatanalyzed
2733patientsrevealedthatmostofthecaseswithdifficult
intubation were in MS III and MS IV categories.20 Another
study investigated 1200 patients and detected 78%
sensi-tivity,85%specificity,19%PPVand99%NPVfor MS.Inthe
present study, the sensitivity, specificity, PPV andNPV of
theMSwere30.5%,97%,59.3%and93.6%,respectively.The
lowersensitivityoftheMS,withanincreasedMSfoundin
only30.5%ofcaseswithdifficultintubations,maystemfrom
the presence of laryngeal pathologies in our study
popu-lation. The results demonstrate that MS III and MSIV are
lesseffectiveinthepredictionofdifficultintubationsina
generalpatientpopulation.
Frerketal.reported81.2%sensitivityand81.5%
speci-ficityfortheCLS.21 Wedeterminedcorrespondingvaluesof
75.3%and98%fortheCLS.Thehighersensitivityand
speci-ficityvalues found in ourstudy indicate thatthe CLS can
predictdifficultintubationprocedures.
ATMDshorterthan6cmcanleadtodifficultintubations
for anesthesia.22 Jimson etal. reportedthatthe
sensitiv-ity,specificity,PPVandNPVofashortTMDwere32%,80%,
20%and 89%, respectively.23 Ourcorrespondingvalues for
thesensitivity,specificity,PPVandNPVofashortTMDwere 23.9,99.4,81.6and93.1%respectively.Ourstudyindicates thatashortTMDisanimportantpredictorofdifficult
intuba-tionprocedures.AhigherPPVmightberelatedtolaryngeal
pathologyassociatedwithashortTMD.
Manyauthorshaveevaluatedpatientsundergoing
surgi-calinterventionswithrespect torestricted cervical ROM.
Arne et al. detected restricted cervical ROM in 4.2% of
patientsandobserveddifficultintubationproceduresin54%
ofthesecases.24 However,wedetectedrestrictedcervical
ROMin3.2%ofourpatientsanddifficultintubation
proce-duresin75.8%ofthesecases.Cattanoetal.reportedthat
thesensitivity,specificity,PPVandNPVofrestricted cervi-calROMwere17%,91.8%,5%and98%,respectively.19Jimson
etal.foundcorrespondingpercentagesforsensitivity, speci-ficity,PPVandNPVof10%,93%,18%and87%,respectively.23
In our study, the sensitivity, specificity, PPV and NPV of
restrictedcervicalROMwere28.1%,99.1%,75.8%and92%,
respectively. These results indicate a marked correlation
between restricted cervical ROM and difficult intubation.
ThehigherPPVin ourstudymight beduetothepresence
oflaryngeal pathologies,inadditiontorestricted cervical ROM.
Inastudythatevaluatedpatientsforanyprevious
evi-denceofadifficultairway,ahistoryofadifficultairwaywas notedin0.6%ofthepatientsand77.8%ofthesehad experi-enceddifficultintubationprocedures.24Wenotedahistory
ofadifficultairwayin1.5%ofthepatients,ofwhom86.2%
hadundergonedifficultintubationprocedures.Inthe
above-mentionedstudy,thesensitivity,specificity,PPVandNPVof
ahistoryofadifficult airwaywas14%, 99%,78%and96%,
respectively.Wedeterminedcorrespondingratesof21.5%,
99.7%,86.2%and92.5%for thesensitivity,specificity,PPV
andNPV,respectively.Similartotheabovementionedstudy,
ourstudyalsorevealedadistinctcorrelationbetweena his-toryofadifficultairwayanddifficultintubationprocedures.
Aseparatestudyreportedthepresenceofavocal cord
massin 3% of patients whohad undergone surgical
inter-ventions,with19.2%ofthesehavingdifficultintubations.24
We detected a vocal cordmass in 10.8% of our patients,
49.5%ofwhomexperiencedintubationdifficulties.The
sen-sitivity,specificity,PPVandNPVofthepresenceofavocal
cordmasswere70%,87%,19%and99%,respectively.24 The
correspondingestimates of thesensitivity, specificity,PPV
andNPVinthecurrentstudywere71.1%,94.1%,49.4%and
97.5%,respectively.DiversePPVmightstemfromvariations
in the sizes of vocal cord masses and different laryngeal
pathologies.Boththeliteraturedataandtheoutcomesof
ourstudyemphasizetheimportanceofavocalcordmassin
thepredictionofdifficultintubation.
Arne et al. performed a logistic analysis of indicators
of difficult intubation and calculated the odds ratios and
short TMD (1.36 and p<0.0001), restricted cervical ROM (1.46 and p<0.0149) and any previous evidence of diffi-cultintubation(3.28andp<0.0084).24However,Sheffetal.
reportedoddsratiosforMSof2.75andPvaluesof<0.035 andoddsratiosandPvaluesof.17and<0.002,respectively, forahistoryofdifficultintubation.14OuroddsratiosandP
values,respectively, forthese predictorswere asfollows:
MS(1.736and<0.003)CLS(6.159and<0.0001),restricted cervicalROM(6.518and<0.0001),historyofdifficult
intu-bation (2.887 and <0.011) and presence of a vocal cord
mass (2.968 and<0.0001). According to this analysis,the MS,theCLS,restrictedcervical ROM,ahistory ofdifficult
airway,ashortTMDandthepresenceofavocalcordmass
arestatisticallysignificantpredictorsofdifficultintubation.
However,whencomparedwiththecombinedassessmentof
allthepredictors,thepredictivevalueofashortTMDdid
notappeartobestatisticallysignificantpredictorofdifficult intubation.
Asmostpatientsarenotat riskfordifficultintubation,
abnormally high rates of PPV cannot be possibly
encoun-tered. The only way to increase the PPV is by using a
combination of diagnostic tests.23,25 Many authors have
reportedincreased PPVwith thecombined useof the MS
andmeasurementsoftheTMD.24 An idealtest should
pre-dict allpotential casesof difficult intubationsand detect
alleasyones.However,thusfar,neithermeta-analysesnor
theASAhasdefinedanidealpredictivetest.26Meta-analyses
havedemonstratedgreatdifferencesamongdataretrieved
fromvariousmedicalcentersand indicated that
individu-allythese tests had minor or moderate predictive values
forpotentiallydifficultintubationprocedures.Studiesthat
comparedENTpatientswiththegeneralpatientpopulation
reportedthatpredictivevaluesinENTpatientswere
compa-rablewiththosefoundinthegeneralpatientpopulationwith a1---2%intergroupdifferenceintheNPV.18,27
Even ifpatients areevaluatedbypreoperatively
medi-cal anamnesis, physical examination, and tests, difficult
intubation cannot be accurately predicted. Nevertheless,
preoperative application of the aforementioned tests is
useful and necessary for preintubation preparation and
prediction of potentially difficult intubation procedures.
Preciseselectioncriteriaarenotavailable for the
numer-ouspreoperativetests.Differentlevelsofexpertiseamong
anesthetistsanddiverseintubationtechniquesfurther
com-plicatetheselectionprocess.However,thecombineduseof
severalbedsidetests,suchastheMSandtheTMDtestscan
berecommended.28 Incaseswhere thepreliminary
evalu-ationrevealsa slightsuspicion,preintubation preparation
willbebeneficialforthesuccessfulmanagementofdifficult intubation.
In conclusion,preoperative testspredictive of difficult
intubation proceduresperformed in caseswith DL in ENT
surgeryhavegreatlyoverlappedwiththosereportedforthe
general patientpopulation. Laryngeal pathologiesexplain
thedifferencesbetweenthepatients inthecurrent study
andthoseinthegeneralpopulation.Theyalsoexplainthe
lowersensitivityoftheMStestresults.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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