RevBrasAnestesiol.2014;64(1):62---65
REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
OfficialPublicationoftheBrazilianSocietyofAnesthesiology www.sba.com.brSCIENTIFIC
ARTICLE
Effectiveness
of
the
C-MAC
video
laryngoscope
in
the
management
of
unexpected
failed
intubations
Alper
Kilicaslan
∗,
Ahmet
Topal,
Aybars
Tavlan,
Atilla
Erol,
Seref
Otelcioglu
DepartmentofAnaesthesiology,MeramMedicalFaculty,NecmettinErbakanUniversity,Konya,Turkey
Received2December2012;accepted20March2013
KEYWORDS Airwaymanagement; Laryngoscopy; Difficultintubation
Abstract
Backgroundandobjectives: The purposeof thisstudy was to review theexperiences ofan anesthesiologydepartmentregardingtheuseofaC-MACvideolaryngoscopeinunexpectedfailed intubationattempts.
Methods:Data were analyzed from 42 patients whose intubation attempts using Macintosh directlaryngoscopeshadfailed,andonwhomaC-MACvideolaryngoscopewasutilizedasthe primaryrescuedevice.ThesuccessrateofC-MACinintubationwasassessed,andlaryngeal viewsfrombothdeviceswerecompared.
Results:TheCormackandLehanescorewasIIIin41patients,andIVinonepatient,withthe Macintoshlaryngoscope,whileCormackandLehanescorewasIin27patients,IIin14andIII inonewithCMAC.Tracheal intubationwithCMACwassuccessful onthefirstattempt in36 patients(86%),andonthesecondattemptin6patients(14%).Nocomplicationswereobserved otherthanminordamage(bloodonblade)in8patients(19%).
Conclusion:ThesedataprovideevidencefortheclinicaleffectivenessofC-MAC videolaryngo-scopeinmanagingtheunexpectedfailedintubationsinroutineanesthesiacare.The C-MAC videolaryngoscopeisefficientandsafeasaprimaryrescuedeviceinunexpectedfailed intuba-tions.
©2013SociedadeBrasileiradeAnestesiologia.PublishedbyElsevier EditoraLtda.Allrights reserved.
Introduction
Twocapabilities thatan anesthesiologist mustpossess are accurate assessment and efficient control of the airway.
∗Correspondingauthor.
E-mail:[email protected](A.Kilicaslan).
Despite the strategicadvancements in predicting difficult airway, the efficacy of routine preoperative tests is still limited.
Unexpected difficult laryngoscopy and failed tracheal intubation areamong the majorcauses of morbidity and mortality associated with anesthesia.1,2 In addition to
the low success rates of multiple intubation attempts, complicationssuchasairwaytrauma,hypoxia,tachycardia,
0104-0014/$–seefrontmatter©2013SociedadeBrasileiradeAnestesiologia.PublishedbyElsevierEditoraLtda.Allrightsreserved.
C-MACvideolaryngoscopeintheunexpectedfailedintubations 63
increase in blood pressure and intracranial and intraoc-ular pressure, aspiration, and cardiac arrest may arise.3
TheAmericanSocietyofAnesthesiologists(ASA)haslimited repeated use of the same technique for the prevention of complications in difficult airway, and recommends the utilization of alternative techniques.4 Videolaryngoscopes
introduceapotentialsolutionthatenablesbetterimaging ofthelarynxwhenconventionallaryngoscopesfail.5
The C-MAC® videolaryngoscope (Karl Storz, Tuttlingen,
Germany)featuresstandardMacintoshbladedesignswithan externallightsourceandsmalldigitalcameraatthedistal thirdofthebladethatextendtoavideodisplaymonitor.6
Unlikevideolaryngoscopeswithacuteangulatedblades,itis possibletoseetheglottisintwoways:thefirstisthedirect viewoftheglottiswiththenakedeye,andthesecondisthe indirectviewfromthemonitorwiththehelpofaminiature cameraatthetipoftheblades.
Studies have shown that the limited laryngeal view improved with C-MAC following direct laryngoscopy.6,7
Successful applications of a C-MAC in expected difficult laryngoscopysettings have alsobeen reported.8 However,
there is insufficient knowledge on the efficacy of C-MAC andpotentialcomplicationsinemergenciesduringeveryday clinicalpractices,suchasunexpected(unpredicted)failed intubation.
AC-MACisusedastheprimaryemergencyairwaydevice in unexpected failed intubation cases in our department, and these cases are recorded using a standardized form. The purpose of this retrospective review wasto evaluate the utilityof a C-MAC that isused afterfailedintubation attemptswithaconventionalMacintoshlaryngoscope.
Methods
Setting
This studyanalyses therecordeddata onthedifficult air-wayformsfrompatientswhounderwenttrachealintubation under general anesthesia in the operating room. In our operating room practices, we use C-MAC whenever suit-able,ifprimaryconventionallaryngoscopyattemptreveals adifficultintubationandweareabletoprovideenough ven-tilationusingamask.However,aC-MACisnotusedinevery difficultlaryngoscopycase sinceanumberofour24 oper-ating rooms are locatedin different blocks,and we have only1videolaryngoscope(C-MAC)withano.3bladeinour department.Moreover,familiarizationwithhowtousethe newlyacquiredC-MACinourdepartmenthasnotyetbeen fullyachieved.Therefore,someanesthesiologistsdonotuse theC-MACbecauseitisnotavailableorbecausetheyarenot trained.Incasesofdifficultlaryngoscopy,asemi-rigidstylet isusedtoguidetheendotrachealtube.TheC-MACisused byanesthesiologistswithpriortrainingandover20clinical useexperiences,wheneverpossible.
In our department, information on unexpected failed intubation cases, applied techniques and results are recorded in a prepared standardized form. This form includes thefollowinginformation: patientcharacteristics (includingage,gender, ASA status),anesthesiatechnique, difficult facemask ventilation, device(s) used for intuba-tion,person(s)whoperformedtheintubation,thenumberof
intubationattempts,useofstylet,externallaryngeal manip-ulations,successofintubation,complications.
The best laryngeal views obtained on consecutive attemptswererecordedasCormackandLehane(CL)grade.9
An attempt was defined as insertion of the endotracheal tubeinto theoropharynx. Retractionof thetube or unin-tendedesophagealintubationis definedas‘‘failure’’. The completionoftheunexpectedfailedintubationformsis trig-geredbytheanesthesiologyspecialist’sclinicaldecision.
Studydesign
Afterreceivingapprovalfromtheinstitutionalreviewboard, therecordeddifficultairwayassessmentformsforpatients, whounderwent general anesthesiabetween the dates of April2011and2012,wereretrospectivelyreviewed. Infor-mationregardingcases,inwhichaC-MACvideolaryngoscope wasusedfollowingafailedorotrachealintubationattempt witha RegularMacintoshlaryngoscope(Heineinstruments Germany),wasanalyzed.
Fromtheserecords,patientsovertheageof18,whohad nohistoryof difficult intubationor difficult airway, hada Mallampatiscoreof≤2,andnormalairwayexamination,but hadafailedintubationattemptfollowinginductionof anes-thesia,werespecified.Emergencysurgery,obstetriccases, andcasesinwhichdirectlaryngoscopewassimultaneously usedwitha C-MAC by differentanesthesiology specialists wereexcludedfromthestudy.
Outcomemeasures
Theprimaryoutcome measurewastheintubation success of C-MAC in direct laryngoscopy and unexpected difficult intubationcases.The second outcomemeasures werethe Cormack---Lehaneviewsthroughdirectlaryngoscopyand C-MAC.
Statisticalanalysis
Statistical analysis was carried out with the 16.0 ver-sion of the SPSS programme for Windows (SPSS Inc., Chicago,IL). The Wilcoxon signed-rank test was used for the comparison of data obtained from the same patient using two separate devices. Normally distributed numer-ical data were presented as mean, standard deviation, andrange(minimum---maximum).Categoricalvariableswere presentedascountsandpercentages.p-Valuesoflessthan 0.05wereacceptedassignificant.
Results
64 A.Kilicaslanetal.
5774 Total intubations
53 Unexpected failed intubations with the ML
- age>18
- no history of difficult airway - Mallampati I-II
- normal airway examination
11 Excluded
- emergency surgery - obstetric cases
42 Included
- CMAC intubations after failed intubations with ML performed by same anesthesiologist
Figure1 Chartflowofpatients’selectionandinclusion.
The demographic and clinical characteristics of the patientsarepresentedinTable1.Afterinductionof anes-thesia,allpatients’lungscouldbeventilatedbybag-mask ventilation,andnodesaturationoccurred.
The results of direct laryngoscopy using a Macintosh revealeda CLgradeof 3in 41patients(97.6%), andaCL gradeof 4 in1 patient(2.4%). Thena CL scorewasIII in 41patients(97.6%),andIVinonepatient(2.4%),withthe Macintoshlaryngoscope,whileCLscorewasIin27patients (64%),IIin14patients(33%),andIIIinonepatient(3%)with CMAC.
Table 1 Patient characteristics. Data are mean (SD) [range],orpercentageandnumbers.
Numberofpatients 42
Gender(male/female) 26(62)/16(38)
Age(years) 45.9(12.5[24---67])
Bodyweight(kg) 82.1(12.6[50---118])
Height(cm) 171.1(8[154---188])
BMI(kgm−1) 28.1(7.9[19.1---42.2])
ASAclass(I/II/III) 16/14/12
Mallampaticlass(I/II) 7(17)/35(83)
Thyromentaldistance(mm) 72(8.5[65---105])
Openingmouth(mm) 39.8(5.4[28---52])
Typeofmusclerelaxant(n)
Rocuronium 28(67)
Atracurium 14(33)
Typeofsurgery(n)
Cardiacsurgery 9(21.4)
General 18(42.8)
Urologic 6(14.3)
Orthopedic 3(7.1)
Otorhinolaryngological 6(14.3)
0 5 10 15 20 25 30 35 40 45
CL with Macintosh and C-MAC
Number of patients
cI1 cI2 cI3 cI4
C-MAC Macintosh
Figure 2 Comparison ofglotticview (Cormack andLehane grades)usingtheMacintoshlaryngoscopeandC-MAC videolaryn-goscope.
Forty-one laryngeal views (97.6%) improved when a C-MACwasusedafter aMacintosh (Fig.2).The views in 14 patients (33%) improved 1 CL grade, while it improved 2 CL grades in 27 patients (64%) (p<0.001). The laryngeal views of 27 patients (64%) were CL 1, while it was CL 2 in 14patients(33%), andCL3in 1patient(3%). Although theC-MACdidnotimprovethelaryngealviewin1patient, intubation wassuccessful on the second attempt using a C-MAC.
Tracheal intubations were successful in all patients (100%;n=42)whenC-MACwasusedfollowingfailed intuba-tionswithMacintoshblades.Tubeswereplacedonthefirst attempt in 36 patients(86%), and onthe second attempt in6patients(14%)whenusingC-MAC.Eventhoughstylets wereusedinallpatientsduringdirectlaryngoscopy,itwas requiredin6patients(17%)duringvideolaryngoscopy. Exter-nal laryngeal manipulation was performed in all patients duringdirectlaryngoscopybutonlyin6patients(17%)during thesecondattemptwiththeC-MAC.
None of the patients’ surgeries were postponed. No complications were observed other than minor damage (bloodonblade)in8patients(19%).
Discussion
According tothe results of thisstudy, inwhich the expe-riences ofourinstitute werereviewed, videolaryngoscopy with C-MAC improves the glottic view and increases the successrateoftrachealintubationincasesofunexpected difficultintubationswithconventionaldirectlaryngoscopes. Inthisroutineclinicalcareenvironment,thepercentageof successfulintubationintotalwas100%with86%ofpatients intubatedatthefirstattemptwithoutmajorcomplications inpatientswithunanticipatedfailedintubations.
The improvement in the laryngeal viewand successful intubation rateobservedin thisstudyis similartothat of priorstudiesinwhichaC-MACwasused.6,8Piephoetal.have
usedaC-MAClaryngoscopein52patientswithunexpected CL grade 3 or 4 laryngeal views through Macintosh laryn-goscopy. In their study, the laryngeal view wasimproved in 49 patients (94%) using C-MAC, with successful intuba-tionsinallofthem.7Inanew,controlled,randomizedstudy
C-MACvideolaryngoscopeintheunexpectedfailedintubations 65
attempt (138/149; 93%) was higher compared to that of directlaryngoscopy(124/147;84%).8InByhahnetal.study,
in which simulated difficult airway wasestablished using rigid cervical immobilization collars, successful tracheal intubationswereperformedusingC-MACin88%(38/43)of thepatients.10
Earlierstudieshaveshownthatvideolaryngoscopes,such asMcGrath11orGlideScope12thathavemoreangledblades
thantheconventionalMacintosh,improvedglottisviewand increasedintubationsuccessrates.InastudywhereMcGrath Series 5 videolaryngoscopes was evaluated, unsuccessful attemptswerereportedin5%ofthepatients.13 Inanother
study,althoughgoodlaryngealviewswereestablishedwith aGlideScope,6%ofthepatientscouldnotbeintubated.14
When the bladesarecurved furthertoimprove theview, thetipoftheintubationtube,whichhastobedirectedat asteeperangletothelarynx,touchesthefrontwallofthe trachea,preventingitfromgoingfurtherdown.15 In
addi-tiontobeingverysimilartotheMacintoshblade,theblade oftheC-MACisthinner,andtheregionthatmighttouchthe incisors has been narrowed, thus allowing more space to lifttheepiglottiswithacrankmaneuver.9Duetoits
phys-icalandformalcharacteristics,theissueofnotbeingable toadvancethetube furtherindifficultlaryngoscopycases occurslesswhenusingaC-MACblade comparedtoblades withsteeperangles.Accordingtothefindingsofthecurrent study,C-MAChasanincreasedintubationsuccessrate,while enhancinglaryngealviews.
Stylets usedindifficult airwaycasesmaycauseserious complications,suchaspalatal,trachealorpharyngeal per-foration.Dataof thecurrentstudy showthattheneed to use stylets wasgreatly reduced with C-MAC, and that no complications,otherthanminorbleeding,wereobserved.
This study has a number of limitations. First of all, thestudywasretrospectiveinnature,andtheanesthetics andmusclerelaxantscouldnotbestandardized.However, individual circumstances can beassessed equally because laryngoscopies were performed by the same experienced anesthesiology specialists onthe same patient usingboth theMacintoshbladeandC-MACblade.Secondly,thefailed intubation rates donot fully reflect the normal practice, becauseC-MACwasusedasasecondaryairwaydevice with-outattemptingintubationinanumberofpatients,inwhom poorlaryngealviewswereobservedwithMacintosh.
In summary, the C-MAC videolaryngoscope is efficient and safeasa primaryrescue device in unexpected failed intubations. These data provide evidence for the clinical effectiveness ofvideolaryngoscopy in managing the unex-pectedfailedintubationsinroutineanesthesiacare.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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