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Introduction: Difficult tracheal intubation remains a major concern in anaesthetic practice, contributing to significant perioperative morbidity and mortality. Accurate preoperative airway assessment is critical to prevent complications such as hypoxia, brain injury, and cardiac arrest. Among the various bedside tests, the Modified Mallampati Test (MMT) and the Upper Lip Bite Test (ULBT) are simple, non-invasive, and widely used. However, their predictive efficacy remains debated. Objective: To compare the diagnostic accuracy of ULBT and MMT in predicting difficult intubation using the Intubation Difficulty Score (IDS) in patients undergoing elective surgeries under general anaesthesia. Materials And Methods: A prospective observational study was conducted on 102 adult patients (ASA I–II), aged 18–60 years, undergoing elective surgery at Adichunchanagiri Institute of Medical Sciences, Karnataka. Preoperative assessment included ULBT and MMT classification. Intraoperative intubation difficulty was evaluated using the IDS. A score 5 indicated difficult intubation. Statistical analysis was performed using chi-square tests, and diagnostic indices were calculated. Results: Out of 102 patients, difficult intubation was observed in 18 (17.6%). ULBT showed a sensitivity of 90.9%, specificity of 95.7%, and diagnostic accuracy of 97.06%, significantly outperforming MMT (sensitivity: 18.2%, specificity: 75.3%, accuracy: 70.6%). The ULBT demonstrated a statistically significant association with IDS (p lt; 0.001), whereas MMT did not have a statistically significant association (p = 0.731). Conclusion: ULBT is a superior predictor of difficult intubation compared to MMT and should be considered a reliable tool for preoperative airway assessment in elective surgeries.
Keywords: Upper Lip Bite Test; Mallampati Score; Difficult Intubation; General Anaesthesia; Airway Assessment; Intubation Difficulty Score; Predictive Accuracy; UpperLipBiteTest; MallampatiScore; DifficultIntubation; GeneralAnaesthesia; AirwayAssess- ment; IntubationDifficultyScore; PredictiveAccuracy
Difficultyintrachealintubationisapredominantchallengeforanaesthesiologistsandmayleadtomorbidity andmortalityduringsurgery.Difficultyduringintubationisoneofthemostfrequentlyobservedadverse eventsleadingtoanaesthesiamalpracticeclaims.Respiratoryeventsarethecommoncausesofanaesthesiarelatedmorbidity,outofwhich85%arerelatedtomistakesregardingairwaymanagement,resultinginpermanentcerebraldamageduetohypoxiaand30%of anaesthesia-relateddeaths. Airwayassessmentisa mandatorycomponentofpreoperativeanaesthesia evaluation. Inadequateassessmentandplanningof theairwaycouldleadtocatastrophiceffectsthatincludebraininjury,myocardialinjuryanddeath.(1-3) Theincidenceofdifficultlaryngoscopictrachealintubationisbetween1.3%to13%inanoperatingroom setup. Many tests have been proposed to clinically identify patients preoperatively who may have difficultlaryngoscopy. TheMallampatitestwasinitially proposedbyMallampatiSRandwaslatermodified bySamsoonandYoungintofourclasses.Thetestwas classifiedbasedonvisualisationofpharyngealstructureswithmouthfullyopenwiththetonguemaximally protrudingoutandwithoutphonation.Theobserveris toassessthesizeofthetonguewithotherstructuresin theoropharynxandtheabilitytoopenthemouth.(1) TheUpperLipBiteTest(ULBT)wasdevelopedbyKhan etal2003.Thetestisclassifiedaccordingtotheability tobitetheupperlipwiththelowerteeththusassessing therangeandfreemovementofthemandible,itsprotrusionandthearchitectureoftheteeth.(1)Intubation DifficultyScore(IDS)wasdevisedbyAdnetetal.Itisa numericalscorederivedByaddingsevenparameters knowntobeassociatedwithdifficultintubation.The sevenParametersarethenumberofsupplementary operators,thenumberandtypeofalternativeTechniquesused,laryngoscopicgrades,subjectivelifting force,theuseofexternalManipulation,andmobilityor positionofvocalcords.(1-4)Theneedforpredicting theincidenceofdifficultintubationisutmostimportanceandtheabovementionedparametersandtests beingnon-invasive,inexpensive,simpleandeffective bedsidetestswhichareeasytoperformasapreoperativeairwayassessmenttoolcanbebeneficialtopredict difficultairwayandavoidanyuntowardcomplications beforehandandbybeingabletoanticipatethepresenceofadifficultairway,Wewillbeabletoplanfor appropriateequipment,experiencedpersonnel,and alternativeAirwaymanagementstrategies.Therefore, itisimportanttohaveasimpleanddirectPrediction ofdifficultairwaysinseeminglynormalpatients,but thereisnoonestandardtesttoassessandpredictthe same.(4)Inthepresentstudy,theupperlipbiteTestis comparedwiththemodifiedmallampaticlassification inpreoperativelypredictingdifficultLaryngoscopicintubationthatrequiresnospecifictools,takeslittletime toconductanddoesnotcausepatientdiscomfortwith betterstatisticalsignificance.
Tocompareupperlipbitetestwithmodifiedmallampatiscoretopredictdifficultintubationusingintubation difficulty scale in patients undergoing elective surgeriesundergeneralanaesthesia.
ThisstudywasaprospectiveobservationalstudyconductedattheDepartmentofAnaesthesiology,AdichunchanagiriInstituteofMedicalSciences,BGNagara,Karnataka. Thestudyspanned18months,fromDecember2023toJune2025,andwasdesignedtoevaluate andcomparethepredictiveutilityoftwowidelypracticedsimple,non-invasivebedsidetests—theUpper LipBiteTest(ULBT)andtheModifiedMallampatiTest (MMT)—foranticipatingdifficultintubationusingtheIntubationDifficultyScore(IDS)asastandardtool.Study PopulationandSamplingThestudypopulationconsistedofadultpatientsagedbetween18to60years undergoingelectivesurgeriesundergeneralanaesthesiarequiringtrachealintubation.Patientsenrolledin thestudywereassessedaseitherASAPhysicalStatusI orIIaspertheAmericanSocietyofAnesthesiologists classification. A purposive sampling technique was usedtorecruitatotalof102patients.
Patientswereconsideredeligibletoparticipateinthe studyiftheymetthefollowingcriteria: • Agedbetween18and60years.
• ClassifiedasASAPhysicalStatusIorII.
• Undergoingelectivesurgicalproceduresunder generalanaesthesiawithtrachealintubation. • Bothmaleandfemalepatientswereincluded.
Patientswereexcludedfromthestudybasedonthe followingconditions: • Refusaltoparticipateorgiveinformedconsent. • Presenceofupperairwaypathologysuchasfacialfractures,maxillarydeformities,ororaltumors.
• Patientsundergoingemergencysurgicalprocedures.
• Edentulous patients, those with neck contractures,andpatientswithBodyMassIndex(BMI) > 30kg/m .
Prevalenceoftheelectivesurgeries=4% Formula: Z PQ S = D • S –Samplesize • Z –Standardvalueat0.01level=2.58 • P –Proportionofprevalence=4%becomes0.04 • Q = 1 − P = 1 − 0.04 = 0.96 • D –Marginoferrororconfidenceinterval=5% (tobeexpressedindecimals)=0.05
2.58 × 2.58 × 0.04 × 0.96 S = = 102 intotal.
0.05 × 0.05
Uponenrolment,thefollowingdemographicdatawere recorded: • Age • Gender • Height(cm) • Weight(kg) • BodyMassIndex(BMI)calculatedusingtheformula:
Eachpatientunderwenttwoseparatepreoperativeairwayassessmentsbyananaesthesiologistwithaminimumof3years’experiencewhowasblindedtothe intraoperativefindings.Theseincluded:
• Class I: Lower incisors can bite the upper lip abovethevermillionborder.
• ClassII:Lowerincisorscanbitetheupperlipbelowthevermillionborder.
• ClassIII:Lowerincisorscannotbitetheupperlip. This test evaluates mandibular mobility and the anatomyofthemaxillaandmandible.
Conductedwiththepatientinasittingposition,mouth fullyopenedandtongueprotrudedtothemaximum withoutphonation: • ClassI:Softpalate,fauces,uvula,andpillarsvisible.
• ClassII:Softpalate,fauces,anduvulavisible. • ClassIII:Softpalateandbaseofuvulavisible. • ClassIV:Softpalatenotvisible.
Both tests were performed and recorded independentlytopreventobserverbias.
AllpatientsweremonitoredintraoperativelyusingstandardASAmonitoringguidelineswhichincluded: • ECG(Electrocardiogram) • NIBP(Non-InvasiveBloodPressure) • Pulseoximetry(SpO2) • Capnography(End-tidalCO2 usingGEB40monitor) • Optionaladvancedmonitorsasrequiredbythe patient’s condition or at the discretion of the anaesthetist.
• Establishedwithan18G
wideboreIVcannula.
• Preoxygenation: All patients were preoxygenatedfor3minuteswith100%oxygen.
• Patientswerepremedicatedintravenouslywith glycopyrrolate0.2mg,midazolam0.02mg/kg, andfentanyl2 g/kg.Anticipatingpossibleairµ waychallenges,adifficultairwaycartwasmade readilyavailable,andmanagementfollowedthe ASAdifficultairwayalgorithm.
• Generalanaesthesiawasinducedusingtitrated dosesofpropofoluntillossofverbalresponse. Neuromuscularblockadewasachievedwithintravenousvecuroniumbromideatadoseof0.1 mg/kg,andmaskventilationwasmaintainedusinganappropriatelysizedfacemask.
• PatientPositioning: Standard‘sniffingposition’ usingapillowundertheocciput.
– Anydeviationfromthisposition(e.g.,ramping)wasrecordedandfactoredintotheIDS scoring.
• Laryngoscopy: Performed using a Macintosh bladesize3forfemalesandsize4formales.
– Laryngoscopy was performed from the right side of the mouth with the tongue swepttotheleft.
Females:7.0-or7.5-mminternaldiameter.
– Males:8.0-or8.5-mminternaldiameter.
Thefirstattemptatintubationwasmadebyatrained anaesthesiologistwithatleast3yearsofexperience. Ifunsuccessful,furtherattemptsoradjunctswereemployedandnotedaspertheIDSscoring.
Extrapointswereawardedforanypositionshiftfromthe standardposition(forinstance,stacking,ramping,or alteringthestandardposition).Anyadditionalmethod usedinadditiontotheconventionaldirectlaryngoscopy willreceiveextrapoints(forinstance,videoassistedintubation,fibreopticintubation,Bougieuse,andglide scopeuse).
TheanaesthetistassessedthedegreeofintubationdifficultybydocumentingthevalidatedIntubationDifficultyScore(IDS)aftercompletionoftheprocedure. TheIDScomprisessevencomponents,designatedN1 toN7, andthetotalscoreiscalculatedbysumming thesevariables.AnIDSvalueoffiveorgreaterwasconsideredindicativeofdifficultintubation,whileascore belowfivewasregardedaseasyintubation.
ThedifficultyofintubationwasassessedusingthevalidatedIntubationDifficultyScoreproposedbyAdnetet al.,whichincludessevencomponents:
Numberofadditionalintubationattemptsisin-
dicatedbyN1: – 0 =firstattempt – 1 =foreachsupplementaryattempt.
N2 Numberofadditionalpersonsdirectlyattemptingintubation(notassistingintubation)isindicatedbyN2: – 0 =oneoperator – 1 =foreachsupplementaryoperator N3 NumberofalternativetechniquesusedisindicatedbyN3: – 0 =forstandardtechnique – 1 =foreachalternatetechnique Standard technique means pillow under the headandMacintoshsize3forwomanandsize4 formen.
Alternativetechniqueincludes: 1. Changeinpatientpositioning(Ramping/Stacking);Changeofinstruments(Blade,ET tube,Additionofstylette,Bougie) 2. Changeinapproach(Nasotracheal/orotracheal);Useofotherinstruments(Fibreoptic,Glidescope,Videoassisted,intubation throughalaryngealmask)
N4 LaryngoscopyviewasdefinedbyCormackand LehaneisindicatedbyN4: – GRADE1:FullexposureofGlottis=N4=0 – GRADE2:Anteriorcommissurenotvisualized=N4=1 – GRADE3:OnlyEpiglottisvisualized=N4=2 – GRADE4:Noglottisstructurevisualized= N4=3 N5 Theliftingforceappliedduringlaryngoscopyis indicatedbyN5: – 0 =iflittleeffortisnecessary – 1 =ifsubjectivelyincreasedliftingforceis necessary. (This notion is based on the operator’s impression that an abnormal amountofforcewasusedcomparedwith routinepractice) N6 NeedtoapplyexternallaryngealpressureforoptimizedglottisexposureisindicatedbyN6.
N7 Positionofvocalcordsatintubationisindicated byN7: – 0 =ifabductedornotvisible – 1 =ifadducted(impedimenttotubepassage) Thestudypopulationaspersamplesizehastobedividedintoeasyintubationgroup(IDSscore < 5)and difficult intubation (IDS score ≥ 5) groups. Need to entervariablesofallpatientsintothegroups. 1. UpperLipBiteTestscore(ULBT) 2. ModifiedMallampatiscore(MMT)
Amongthe102patientsincludedinthestudy,thedistributionacrossagegroupswasasfollows:18–25years (22patients,21.6%),26–35years(24patients,23.5%), 36–45years(27patients,26.5%),and46–60years(29 patients,28.4%).Achi-squaretestwasperformedto assesswhethertheobservedagedistributionsignificantlydifferedfromanequaldistribution. Thetest yieldedachi-squaretestof1.14withap-valueof0.768, indicatingnostatisticallysignificantdifferenceinage distribution across the defined groups (p > 0.05). Thus,theagegroupswererelativelybalanced,andno agegroupwasover-orunder-representedinthestudy sample.
Table 1. AgeGroupDistributionofpatients
18–25 22 21.6 26–35 24 23.5 36–45 27 26.5 46–60 29 28.4 chi-squaretest=1.14, p =0.768
Amongthe102patientsstudied,60(58.8%)weremale and42(41.2%)werefemale.Achi-squaretestwasappliedtoevaluatewhetherthisdistributionsignificantly deviatedfromanexpected1:1male-to-femaleratio. The test yielded a chi-square statistic of 3.18 with a p-valueof0.075. Sincethisp-valueexceedstheconventionalthresholdof0.05,thedifferencewasnotstatisticallysignificant.Thus,thesexdistributioninthe studysamplewasreasonablybalanced.
SexDistributionofpatients
Male 60 58.8 Female 42 41.2 chi-squaretest=3.18, -value=0.075
Table 3. Generalphysicalexaminationfindingsofthe studyparticipants
Height(cm) 163.8 9.09 138.8 183.5 Weight(kg) 65.84 11.33 42 97.6 BMI(kg/m ) 24.74 5 15.4 40.1 Themeanheightofthe102patientswas163.8±9.1cm, withvaluesrangingfrom138.8cmto183.5cm.Theaveragebodyweightwas65.8±11.3kg,rangingfrom42.0 kgto97.6kg.ThemeanBodyMassIndex(BMI)was24.7 ±5.0kg/m2,withaminimumof15.4andamaximumof 40.1kg/m2,indicatingthatmostparticipantsfellwithin thenormaltooverweightrange.Theseanthropometricmeasurementsprovideabaselineoverviewofthe physicalcharacteristicsofthestudypopulation.
Table 4. ASAClassificationofpatients
ASAI 60 58.8 ASAII 42 41.2 chi-squarestatistic=3.18, p =0.075 Outof102patientsassessedpreoperatively,60(58.8%) wereclassifiedasASAIand42(41.2%)asASAII.To determinewhetherthisdistributionsignificantlydifferedfromanexpectedequaldistribution,achi-square goodness-of-fittestwasconducted.Thetestyielded achi-squarestatisticof3.18withap-valueof0.075. Sincethep-valueisgreaterthan0.05,thedifferencein ASAclassificationdistributionwasnotstatisticallysignificant.Thisindicatesthatthestudypopulationwas fairlybalancedintermsofASAphysicalstatus,witha p slightpredominanceofASAIpatients.
Table 5. Distributionofstudypopulationaccordingto ModifiedMallampatitest(MMT)
ClassI 35 34.3 ClassII 35 34.3 ClassIII 23 22.5 ClassIV 9 8.8 chi-squarestatistic=18.00, p =0.0004
The study population was classified into four categoriesbasedontheModifiedMallampatiTest(MMT). Amongthe102patients,35(34.3%)eachwereclassifiedasClassIandClassII,23(22.5%)asClassIII,and9 (8.8%)asClassIV.Achi-squaretestwasconductedto assesswhetherthisdistributiondifferedsignificantly fromanequaldistributionacrossthefourclasses.The testyieldedachi-squarestatisticof18.00withap-value of0.0004,indicatingastatisticallysignificantdifference (p<0.05). Thus,thedistributionofMMTclasseswas skewed, withahigherproportionofpatientsfalling intoClassIandIIcategories,andfewerinClassIIIand IV,suggestingthatmostpatientshadfavorableairway anatomyforintubation.
Table 6. Distributionofstudypopulationaccordingto UpperLipBitetest(ULBT)
ClassI 47 46.1 ClassII 37 36.3 ClassIII 18 17.6 chi-squarevalue=12.76, p =0.0017
BasedontheUpperLipBiteTest(ULBT),47patients (46.1%)werecategorizedasClassI,37(36.3%)asClass II, and 18 (17.6%) as Class III. A chi-square test was conductedtoevaluatewhetherthisdistributionsignificantlydeviatedfromanequaldistributionacrossthe threeULBTclasses.Thetestyieldedachi-squarevalue of12.76withap-valueof0.0017,indicatingastatisticallysignificantdifference(p<0.05). Theseresults suggestthatthemajorityofpatientsdemonstratedfavorablemandibularmobility(ClassIandII),withfewer individualsexhibitingcharacteristicsassociatedwith potentialdifficultintubation(ClassIII).
Table 7. DistributionofIntubationdifficultyscale scores
Easy(IDS < 5) 84 82.4 Difficult(IDS 5) 18 17.6 ≥ chi-squarevalue=42.71, p-value < 0.0001
BasedontheIntubationDifficultyScale(IDS),84patients(82.4%)wereclassifiedashavingeasyintubation(IDS < 5),while18patients(17.6%)experienced difficult intubation (IDS ≥ 5). A chi-square test was performedtoevaluatewhetherthisdistributionsignificantlydeviatedfromanexpectedequaldistribution. Thetestyieldedachi-squarevalueof42.71witha pvalue 0.0001, indicatingahighlysignificantdiffer- < ence. Theresultsshowthatthevastmajorityofpatientshadeasyintubation,aligningwiththegeneral populationtrend,andconfirmingtherelativerarityof difficultairwayscenariosinelectivesurgicalcases.
Table 8. AssociationofMMTwithDifficultIntubation
ClassI 9 26 35 ClassII 11 24 35 ClassIII 7 16 23 ClassIV 1 8 9
2 , =0.650 χ = 1.64 p
The association between Modified Mallampati Test (MMT)classandintubationdifficulty(aspertheIntubationDifficultyScale,IDS)wasanalyzedamong102 patients. Difficultintubation(IDS ≥ 5)wasobserved acrossallMMTclasses.However,achi-squaretestfor associationyieldeda χ valueof1.64anda p-valueof 0.650,indicatingnostatisticallysignificantassociation betweenMMTclassanddifficultintubation(p > 0.05). TheseresultssuggestthatMMTclassalonemaynot reliablypredictintubationdifficultyinthisstudypopulation.
Table 9. AssociationofULBTwithDifficultIntubation
ClassI 10 37 47 ClassII 14 23 37 ClassIII 4 14 18
2 and -value=0.207 χ = 3.15 p
TheassociationbetweenUpperLipBiteTest(ULBT) classandintubationdifficulty(IDSclassification)was examinedin102patients. Amongthoseclassifiedas ULBTClassI,10(21.3%)experienceddifficultintubation,comparedto14(37.8%)inClassIIand4(22.2%)in ClassIII.Achi-squaretestyieldeda 2 valueof3.15and χ a p-valueof0.207.Sincethe p-valueisgreaterthan0.05, theassociationwasnotstatisticallysignificant.These findingssuggestthatwhileahigherproportionofdifficultintubationswasnotedinULBTClassII,ULBTclass wasnotsignificantlyassociatedwiththelikelihoodof difficultintubationinthiscohort.
Table 10. DiagnosticAccuracyofMMTandULBT
TrueNegative 70 89 TruePositive 2 10 FalseNegative 9 1 FalsePositive 21 2 Sensitivity 18.20% 90.90% Specificity 75.30% 95.70% PositivePredictiveValue 8.00% 71.40% NegativePredictiveValue 88.60% 98.90% DiagnosticAccuracy 70.59% 97.06% P Value 0.731 <0.001
ThediagnosticperformanceoftheModifiedMallampatiTest(MMT)andUpperLipBiteTest(ULBT)inpredictingdifficultintubationwasevaluatedusingsensitivity,specificity,predictivevalues,andoveralldiagnosticaccuracy.ForMMT,thetestyieldedasensitivity of18.2%andspecificityof75.3%,withapositivepredictivevalue(PPV)of8.0%andanegativepredictive value(NPV)of88.6%.Incontrast,ULBTdemonstrated markedlysuperiorpredictiveability, withasensitivityof90.9%,specificityof95.7%,PPVof71.4%,and NPVof98.9%. ThediagnosticaccuracywasalsosignificantlyhigherforULBT(97.1%)comparedtoMMT (70.6%).Thedifferenceinpredictiveperformancewas statistically significant, with a p-value of <0.001 for ULBT,comparedtoanon-significant p-valueof0.7310 forMMT.ThesefindingssuggestthatULBTisamore reliableandaccuratepreoperativescreeningtoolfor anticipatingdifficultintubationthanMMTinthisstudy population.
Predictingadifficultairwayisacriticalcomponentof preoperativeassessment,especiallyinpatientsundergoingelectivesurgeriesundergeneralanaesthesia[1]. Failuretoanticipateandmanageadifficultairwaycan leadtoseverecomplications,includinghypoxia,aspiration,trauma,andevendeath.Consequently,various bedsidescreeningtestshavebeendevelopedtohelp cliniciansidentifypatientsatriskofdifficultintubation. AmongthemostcommonlyusedaretheModifiedMallampatiScore(MMS)andtheUpperLipBiteTest(ULBT), both of which are simple, non-invasive, and can be performedwithinsecondsduringthepre-anaesthetic evaluation[2].
TheModifiedMallampatiScoreevaluatesthevisibilityoforopharyngealstructureswhenapatientopens theirmouthandprotrudestheirtongue. Itclassifies theairwayintofourgrades, withhighergradessuggestingmoredifficultlaryngoscopy.Whilewidelyused andeasytoadminister, theMMSissubjective, influencedbypatientcooperation,andhasshownvariable sensitivityandspecificityindifferentpopulations[3]. Ontheotherhand,theUpperLipBiteTestassesses mandibular mobility and the degree of maxillopharyngealspacebyaskingthepatienttobitetheupper lipwiththelowerincisors.Itcategorizespatientsinto threeclassesbasedonhowmuchoftheupperlipcan becovered,withClassIIIassociatedwithdifficultintubation.TheULBTisconsideredmoreobjectiveandhas demonstratedbetterpredictivevalueinsomestudies, thoughitsperformancecanvarybasedonethnicand anatomicalfactors[4].
Despitethewidespreaduseofthesetests,nosingle predictorhasproventobeentirelyreliable.Combining tests or comparing them can enhance accuracy andprovideamorecomprehensiveairwayassessment. ThishasledtoincreasedinterestinevaluatingthecomparativeperformanceofMMSandULBTinpredicting difficultintubation,especiallyinvariedclinicalsettings suchaselectivesurgeriesundergeneralanaesthesia [5].Thepresentprospectiveobservationalstudywas conductedtocomparethesensitivity,specificity,positive predictive value, and negative predictive value oftheUpperLipBiteTestandtheModifiedMallampatiScoreaspredictorsofdifficultintubationinadult patientsundergoingelectivesurgicalprocedures[6]. Byestablishingtherelativeefficacyofthesetwotests, thestudyaimstoprovideevidence-basedguidanceon theiruseinroutinepre-anaestheticassessment,particularlyinresource-constrainedenvironmentswhere rapidandaccuratescreeningisvital.Thiscomparison mayhelpanaesthesiologistsoptimizeairwaymanagement strategies, reduce perioperative risks, and improvepatientsafety[7].
In our cohort of 102 elective surgery patients, age groupswerefairlybalanced:18–25years(21.6%),26– 35 (23.5%), 36–45 (26.5%), and 46–60 (28.4%), with achi-squaretestconfirmingnosignificantvariation acrossgroups( 2 , ).Incontrast,Kar χ = 1.14 p = 0.768 etal. (2022)atatertiary-carehospitalinIndiastudied225patientsandnotedapredominanceinthe31– 40yeargroup,althoughexactpercentageswerenot specified,andtheyobserveda10.2%rateofdifficult intubationoverallusingULBTandMallampatiscores. Additionally,alargeULBT/Mallampaticomparisonin Pakistan(n ≈ 910)reportedthatmostsubjectswere aged20–30(39.1%),followedby31–40(30.7%)and41– 50(30.2%).Whiledemographicpatternsoverlap,our agedistributionshowsamoreevenspreadandslightly olderagerepresentationrelativetothesecomparative studies[8,9].
Amongthe102patientsinourstudy,malescomprised 58.8%andfemales41.2%,showingamodestmalepredominance.Thechi-squaretest( 2 , ) χ = 3.18 p = 0.075 indicatesthatthisgenderdistributiondoesnotsignificantlydeviatefromanexpected1:1ratio,suggesting areasonablybalancedsample. Incomparison,most publishedairwayassessmentstudies—includinglarge cohortsevaluatingULBTandMMT—alsofeatureslight male predominance. For example, a systematic reviewofULBTacrossmorethan18,000patientsfound nosignificantsex-basedvariationinpredictiveaccuracyfordifficultintubation. Similarly,aprospective observationalstudyof450electivesurgerypatients reportedmalesformingabout52%ofthecohort,yet foundtestperformancetobeconsistentacrossgenders. Thus,ourdemographicprofilealignswellwith broaderresearchpatterns,andthelackofasignificant genderimbalancesupportsthegeneralizabilityofour findingswithinmixedadultpopulationsundergoing airwayevaluation[10,11].
Inourstudyinvolving102patients,themeanheight was 163.8 ± 9.09 cm,weight 65.84 ± 11.33 kg,andBMI 24.74 ± 5 kg/m ,withvaluesrangingfrom15.4to40.1 kg/m .Thesefiguresindicatethatthemajorityofparticipantswerewithinthenormaltooverweightrange. Incomparison,Dawoodetal.(2021)reportedamean heightof 163.14±9.63 cm,weight 73.82± 11.7 kg,and BMIof27.7kg/m in150surgicalpatients,indicatinga slightlyhigherBMItrend.Meanwhile,SiddiquiKMet al. (2022)examined300obesepatientswithamean heightof 140.04 ± 14.51 cm,weight 102.84 ± 28.02 kg, andBMI 36.21 ± 2.14 kg/m .Comparedtothesestudies,ourparticipantshadamorefavorableBMIrange, whichcouldaffectthepredictionofdifficultintubation usingairwayassessmenttools[12,13].
Among102electivesurgerypatientsinourstudy,58.8% weremaleand41.2%female.Thesexdistributiondid notsignificantlydeviatefroma1:1ratio(chi-square =3.18, p = 0.075),suggestingareasonablybalanced sample. ForASAphysicalstatusclassification,60patients(58.8%)wereASAIand42(41.2%)wereASAII, againshowingnosignificantimbalance(chi-square= 3.18, p = 0.075).Thisindicatesafairlyhomogeneous preoperativeriskprofile,withaslightpredominance ofhealthierASAIindividuals.
AcomparableprospectiveobservationalstudyfromIndiaassessedsimilarcohortsundergoingupperlipbite test(ULBT)andModifiedMallampatiTest(MMT)topredictdifficultintubation.ThoughexactASAdistribution wasnotreported,thestudybyVargheseetal.(2016)includedpatientsaged18–60yearsundergoingelective surgeries,predominantlyclassifiedasASAIorII,with asimilargenderbalance.Anotherlarge-scaleprospectivestudyinChinabyWangLYetal.involving450patients(ASAI–II)alsoshowedbalancedgenderandASA profiles,withnosignificantdemographicskew.These parallelssuggestthatourdemographicandphysical statusdistributionsarerepresentativeandcomparabletopreviousinvestigationsinthisclinicalcontext [14,11].
Amongourcohort,theModifiedMallampatiTest(MMT) distributionshowedthatClassIandIIaccountedfor the majority of patients (each 34.3%), with fewer in Class III (22.5%) and Class IV (8.8%). A chi-square goodness-of-fit analysis ( 2 , ) χ = 18.00 p = 0.0004 indicatedthatthisdistributiondeviatedsignificantly fromananticipatedequalrepresentation,suggesting mostpatientslikelypresentedwithfavorableairway anatomy suitable for intubation. In comparison, a prospectiveobservationalstudyof225electivesurgery patientsfromIndiafoundasimilarskew—MMTClass Iwasseeninabout43.6%andClassIIin42.7%,with fewerinClassIII(12.0%)andIV(1.8%). Thus,ourresultsalignwellwithpublishedliterature:mostelective surgicalpatientsfallintoMMTClassesI–II,reflecting lowpredictedintubationdifficulty.Ourslightlyhigher prevalenceofClassIIIandIVechoesfindingsindiverse populations, reinforcing that while rare, higher Mallampatigradesremaincriticaltopredictpotentially difficultairwaymanagement[15].
Amongthe102patientsinourstudy,thedistribution across Modified Mallampati Test (MMT) classes was: ClassIandIIeachwith35individuals(34.3%),Class IIIwith23(22.5%),andClassIVwith9(8.8%). Achisquaregoodness-of-fittest( 2 , ) showedthisdistributionsignificantlydivergedfroman evenspread,indicatingmostpatientswereinMMTI orII—suggestinggenerallyfavorableairwayanatomy forintubation.Incomparison,TangXetal.gaveanobservationalcohortof2,522adultsundergoingelective surgerythatreportedULBTgrade2hadasensitivity of75%andspecificityof54%,andULBTgrade3hada sensitivityof28%andspecificityof75%forpredicting difficultintubation;theULBTAUCwas0.69versus0.84 formouthopeningassessments.AnotherIndianstudy byShahPJetal.involving480patientsfoundULBThad sensitivityof ∼75%andspecificityof ∼92%inpredictingdifficultlaryngoscopy—outperformingMallampati andothertests.Together,thesefindingssuggestthat whilemostsubjectsinourcohortfellintoMMTclasses I–II,indicatingamajorityatlowriskfordifficultintubation,ULBTdemonstratedgreaterpredictiveaccuracy inlargermulticentricstudies.EmployingULBTalongsideMMTmayenhanceairwayassessmentprecision duringpreoperativeevaluation[15, ?].
Inourcohortof102patients,84(82.4%)experienced easyintubation(IDS < 5)and18(17.6%)haddifficult intubation(IDS ≥ 5).Achi-squaregoodness-of-fittest yieldedahighlysignificantresult( 2 , χ = 42.71 p < 0.0001), indicating that the distribution is markedly skewedtowardeasyairwayscenarios,apatternconsistent with elective surgical populations. A similar prospective observation by Kamal K et al. studying 200ASAI–IIpatientsundergoingelectivegeneralanesthesia reported an incidence of difficult intubation ofabout6%usingIDS(12of200patients). Another hospital-basedstudybyBadheVKetal. involving70 electivesurgicalpatientsfoundthat5.7%hadIDS ≥ 5 and94.3%hadIDS < 5.
Comparedtoourrateof17.6%,theselowerratesin previousstudiessuggestpotentialdifferencesinpatientdemographicsorairwaydifficultyprevalencein differentpopulations. Ourhigherproportionofdifficultintubationmightreflectanatomicalorprocedural variationbutremainswithinacceptableinternational ranges[?, ?].
Amongour102-patientcohort,distributionacrossModifiedMallampatiTest(MMT)classesshowedsimilarrepresentationinClassesIandII(35patientseach,34.3%), withfewerinClassIII(23patients,22.5%)andClassIV (9patients,8.8%).Achi-squaretestrevealedasignificantdeviationfromequaldistribution( 2 , χ = 18.00 p = 0.0004),indicatingmostsubjectsclusteredinairwayclassesassociatedwitheasierintubation.Inconχ = 18.00 p = 0.0004 trast,SitotMetal. studiesevaluatingbothMMTand UpperLipBiteTest(ULBT)inprospectivesettingshave generallydemonstratedULBT’ssuperiorpredictivecapacity for difficult intubation, especially when combinedwithotherairwaymetrics.Aseparatestudyby ManturJetal.analysedtheULBTinourstudyshowed that47patients(46.1%)wereClassI,37(36.3%)Class II, and 18 (17.6%) Class III. The distribution significantlydifferedfromanequalproportion( 2 , p = 0.0017),againfavoringeasierclasses.Published datafrequentlysupportULBT’shigherspecificityand positivepredictivevaluecomparedtoMMT,particularlyforidentifyingdifficultairways.AlthoughourMMT classificationtrendalignswithexpectationsofairway ease,evidencesuggestscombiningULBTwithMMTand othertests(e.g.,thyromentaldistance)mayenhance theoverallpredictionaccuracy.Thissupportsusinga multimodalapproachinelectivegeneralanesthesiato betteranticipatedifficultintubationscenarios[ , ].
In our cohort of 102 patients scheduled for elective surgeryundergeneralanesthesia,difficultintubation (defined as IDS ≥ 5) was observed in 18 individuals (17.6%), while the remaining 84 (82.4%) demonstratedeasyintubationaspertheIntubationDifficulty Scale. The distribution significantly deviated from anequaldistributionacrosscategories( 2 , p < 0.0001), indicating that difficult airway scenarios were relatively uncommon in our elective surgicalpopulation,aligningwithbroaderprevalenceestimatesinroutinesettings. Comparedtopublished literature—suchasFaramarziEetal.andsubsequent systematic reviews—the occurrence of difficult intubationinourstudylieswithintheexpectedrangeof 1.5%–18%reportedacrossdiversecohorts.Thesecomparisonssupportthegeneralizabilityofourfindings and affirm that, even in tertiary care settings, most electivepatientsmaintainfavorableairwayanatomy notassociatedwithchallengingintubation[ ].
OurcohortdemonstratedULBT’sclearadvantageover MMTinpredictingdifficultintubation:ULBTsensitivity was90.9%,specificity95.7%,PPV71.4%,NPV98.9%, andoverallaccuracy97.06%;MMTshowedlowerfigures (sensitivity 18.2%, specificity 75.3%, PPV 8.0%, NPV88.6%,accuracy70.59%)withanon-significant pvalueof0.731,whileULBTreached <0.001,indicating astatisticallyrobustperformance.Comparableobservationalstudiesreaffirmthesefindings.Forinstance, SinharayandChavan(India)reportedULBTsensitivityof ∼88%,specificity ∼93%,PPV ∼72%,NPV ∼97%, and92%accuracyversusMMTsensitivity ∼19%,specificity ∼92%,and79%accuracy.Together,thedatacorroborateourstudy:ULBTismorereliablethanMMTin predictingdifficultairwayinelectivesurgicalpatients [?].
This prospective observational study demonstrated χ = 12.76 thatUpperLipBiteTest(ULBT)isahighlysensitive, specific,andaccuratepredictorofdifficultintubation inpatientsundergoingelectivesurgeryundergeneral anaesthesia.Incontrast,theModifiedMallampatiTest (MMT)showedlowsensitivityandlimitedpredictive value.
ThediagnosticaccuracyofULBT(97.06%)significantly outperformedthatofMMT(70.59%),makingULBTa moredependabletoolforroutineclinicaluse. Given theease,speed,andreliabilityoftheULBT,itisrecom-
mendedasthepreferredbedsidescreeningtestduring preoperative airway assessment in elective surgical settings.
Thisstudysupportstheevolvingtrendinanaesthesia practicetoadoptmoreaccurate,objective,andpracticaltoolstoensureoptimalpatientoutcomesandreducetheincidenceoffailedintubationsandtheirassociatedcomplications.
χ = 42.71