REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
OfficialPublicationoftheBrazilianSocietyofAnesthesiologywww.sba.com.br
SCIENTIFIC
ARTICLE
Impact
of
the
practising
anesthesiologist
team
member
on
the
laryngeal
mask
cuff
pressures
and
adverse
event
rate
夽
Bülent
Serhan
Yurtlu
∗,
Volkan
Hanci,
Bengü
Köksal,
Dilek
Okyay,
Hilal
Ayo˘
glu,
Is
¸ıl
Özkoc
¸ak
Turan
AnesthesiologyandReanimationDepartment,FacultyofMedicine,ZonguldakKaraelmasUniversity,Zonguldak,Turkey
Received13January2012;accepted20March2013 Availableonline26October2013
KEYWORDS
Laryngealmask airway; Pressure; Anesthesia
Abstract
Objective: Wehaveplannedtoevaluatethelaryngealmaskcuffpressures(LMcp)inflatedby anesthesiaworkersofseveralseniority,withoutusingmanometer.
Methods:180 patients scheduled tohave short duration surgerywith laryngeal mask were includedinthestudy.Fiveanesthesiaspecialists(GroupS),10residents(GroupR)and6 tech-nicians(GroupT)inflatedtheLMc;thereafterLMcpweremeasuredwithpressuremanometer. Participantshaverepeatedthispracticeinatleastfivedifferentcases.LMcphigherthan60cm H2Oatthe initialplacement orintraoperative period were adjustedtonormal range.Sore
throat was questioned postoperatively. Groupswere compared intermsofmean LMcp and occupationalexperience.
Results:AtthesettlementofLM,LMcppressureswithinthenormalrangeweredetermined in26(14.4%)cases.MeanLMcpafterLMplacement inGroup S,RandTwere 101.2±14.0, 104.3±20.5cmH2Oand105.2±18.4cmH2Orespectively(p>0.05).MeanLMcpvaluesinall
measurementtimeperiodswithinthegroupswereabovethenormallimit(60cmH2O).When
groupswerecomparedintermsofLMcp,nodifferencehasbeenfoundamongpressurevalues. Occupationalexperiencewas14.2±3.9;3.3±1.1and6.6±3.8yearsforspecialists,residents and technicians respectivelyand measuredpressure valueswere not differentinregard of occupationalexperience.Seven(3.9%)patientshadsorethroatatthe24thhourinterview.
Conclusion: Consideringlowerpossibility ofnormaladjustmentofLMcpandineffectiveness ofoccupationalexperiencetoobtainnormalpressurevalues,itissuitablethatallanesthesia practitionersshouldadjustLMcpwithmanometer.
© 2013SociedadeBrasileirade Anestesiologia.Publishedby ElsevierEditoraLtda.Allrights reserved.
夽 ApartofthisstudywaspresentedatTurkishAnesthesiaandReanimationCongress2010,Antalya,Turkey.
∗Correspondingauthor.
E-mails:[email protected],[email protected](B.S.Yurtlu).
0104-0014/$–seefrontmatter©2013SociedadeBrasileiradeAnestesiologia.PublishedbyElsevierEditoraLtda.Allrightsreserved.
PALAVRAS-CHAVE
Máscaralaríngea; Pressão;
Anestesia
Impactodoanestesiologistaemtreinamentosobreaspressõesdomanguitode máscaralaríngeaeincidênciadeeventosadversos
Resumo
Objetivo:Planejamos avaliar aspressões do manguito de máscara laríngea (PMML) inflado por profissionais da área de anestesiologia com temposde servic¸o variados, semo uso de manômetro.
Métodos: Centoeoitentapacientesagendadosparacirurgia decurtadurac¸ãocommáscara laríngeaforamincluídosnoestudo.Cincoespecialistasemanestesia(GrupoE),10residentes (GrupoR)eseistécnicos(GrupoT)inflaramosmanguitosdasmáscaraslaríngeas; subsequente-mente,asPMMLforammedidascommanômetrodepressão.Osparticipantesrepetiramessa práticaempelomenoscincocasosdiferentes.AsPMMLsuperioresa60cmH2Onacolocac¸ão
inicialounointraoperatórioforamajustadasparavaloresnormais.Ospacientesforam ques-tionados sobre apresenc¸a dedor de gargantano período pós-operatório. Osgrupos foram comparadosquantoàmédiadasPMMLeexperiênciaprofissional.
Resultados: AoinseriremaML,aspressõesdomanguitodentrodafaixanormalforam deter-minadasem26 (14,4%)casos.AsmédiasdasPMMLapósainserc¸ão daML pelosgruposE, R eT foram101,2±14,0, 104,3±20,5cme105,2±18,4cmH2O,respectivamente,(p>0,05).
A médiadosvalores dasPMMLemtodosos períodosde mensurac¸ãoentreosgruposestava acimadolimite normal(60cmH2O).Quando osgruposforamcomparadosquanto àsPMML,
nenhumadiferenc¸afoiencontradaentreosvaloresdaspressões.Aexperiênciaprofissionalera de14,2±3,9;3,3±1,1e6,6±3,8anosparaespecialistas,residentesetécnicos, respectiva-mente,eosvaloresdaspressõesmensuradasnãoforamdiferentesemrelac¸ãoàexperiência profissional.Setepacientes(3,9%)apresentaramdordegargantaduranteaentrevistarealizada na24ahora.
Conclusão:Levando-seemconsiderac¸ãoumapossibilidademenordeajustedapressãodo man-guitodamáscaralaríngea(PMML)edaineficáciadaexperiênciaprofissionalparaaobtenc¸ão devaloresnormaisdaspressões,éadequadoquetodososprofissionaisdeanestesiaajustemas PMMLcommanômetro.
©2013SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Todosos direitosreservados.
Introduction
Laryngealmask (LM) hasbecome one ofthe cornerstones of airway management after its introduction into clinical practisemorethan20yearsago.Originallyithadbeen rec-ommendedasanalternativeforfacemaskbutupongrowing experiencebutnowithasadefiniteroleinroutine anesthe-siacaresincethen.Today,asanalternativeairwaydevice ithasaworldwideacceptanceanditisassumedthatmore than200millionpatientshadanesthesiawithLM.1
LMhasawelldefinedroleinAmericanSocietyof
Anes-thesiologists(ASA)difficultairwayalgorithmandithaseven
gainedaplacein prehospitalcare,in theresuscitation of
cardiopulmonaryarrestvictims.2,3
Health care providers other than anesthesiologists use
LM especiallyfor emergencyairway care in an increasing
trend.4---6Ontheotherhand,althoughrare,seriousadverse
eventssuchasnerveinjurieshavebeenreportedinthe
lit-erature associated with pressure neuropraxia while using
LM.7---10 Pharyngolaryngeal adverse events are more
com-monafterLMuse,butasrecentlyhavebeendemonstrated,
theincidenceof themcanbe reducedbyadjusting
laryn-geal mask cuff pressure (LMcp) appropiately.7 It can be
expected that pharyngolaryngeal adverse event rate due
toLMcp,canbelowerwhentheexperienceofpractitioner
increases.However,influenceofanesthesiologist’sseniority
andexperience onLMcphas notbeen studied before.We
have hypothesized that increasing experience in
anesthe-siapractisewouldachievecorrectLMcpdetermination,and
reducetheincidenceofoneofthecommonLMassociated
sideeffect,sorethroatrate.Inordertotestthishypothesis,
wehavemeasuredLMcpafterinflationofthelaryngealmask
cuff(LMc)byanesthesiateamworkersofvaryingseniority.
PrimaryoutcomevariablewasinitialLMcp;secondary
out-comevariablewasdeterminedassorethroatrateafterthe
operation.
Methods
After approval of the hospital ethics committee and
obtaining patients’ informed consents, 180 adult patients
scheduled forshort-duration electivesurgeries under
gen-eralanesthesiawereenrolledinthestudy.Allthepatients
were aged between 18 and 70 years, in the ASA I-III risk
group.Exclusioncriteriahaveinvolvedpatientswiththe
his-toriesoffullstomach,recentupper/lowerrespiratorytract
infection,morbidobesity(BMI>40kg/m2),hiatusherniaand
gastroesophagealreflux.
Before the administration of the general anesthetic,
patientswere randomlyallocatedusingarandomsamples
tableintothreegroupsaccordingtoLMpractitioner:
R,n=10),anesthesiatechnician(GroupT,n=6).Each
anes-thesiateamworkerhasperformedatleast5LMinsertionand
inflationthroughoutthestudy.Participantswerenotallowed
to try a second LM insertion-inflation within the same
day.
Uponarrivaltotheoperationtheater,routinemonitoring
(ECG,SpO2andnon-invasivebloodpressuremeasurement)
wasappliedandanesthesiawasinducedwiththesame
pro-tocolinallpatients:fentanyl1gkgandpropofol3mgkg−1.
When the eyelash reflex has been disappeared and the
jaw was relaxed, LM placement was attempted. Dorsum
of LMwaslubricated withawater-basedlubricant before
insertion.LMsizewaschosenaccordingtothe
recommen-dations of the manufacturer (size 3 for adults 50---70kg;
size 4 for 70---100kg and size 5 for those above 100kg).
Practitionerswereallowedtochoseonesizebigger/smaller
if they decide to do so.Standard LM insertion technique
according to manufacturer’s instruction manual has been
usedbyallpractitioners.11 Ventilationwasconfirmedwith
EtCO2onmonitorandchestwallexpansion.IfLMwasnot
properlyplaced on the first trial, then it was re-inserted
andnumberofLM placementtrialwasrecorded.LM
Clas-sic was completely deflated and partially inflated before
insertion.Initial inflationvolumewasnotedandafter the
placement,wheninflatingtheLMc,practitionerswerenot
allowedtoexceedthesuggestedmaximumvolumeforeach
LM size (maximum 20mL for size 3; 30mL for size 4 and
40mLforsize5).Eachpractitionerdecidedtoendinflating
LMc by him/herselfaccording to hispersonal experience.
An anesthesiologistother than thepractitionerthen
mea-suredLMcpwithamanometer(VBMMedizintechnik,GmbH,
Germany) and recorded. If LMcp was higher than 60cm
H2O, it was reduced to60cm H2O. Anesthesia was
main-tainedwith1MACsevofluranein50%oxygen---nitrousoxide
mixture, sevoflurane dose wasadjusted according to
dis-cretion of attending anesthesiologist. LMcp measurement
wasrepeatedwith15minintervals andintracuff pressure
wasadjusted to60cmH2Oifitwashigher.LMcponserial
measurementswererecordedalso.Attheendofthe
oper-ation,LMwasremovedwithoutsuctioningwhenthepatient
wasawake.Adverseeventsduringextubationsuchas
laryn-gospasm and bloodstain on removed LM were recorded.
Patientsweretransferredtopostoperativecareunit,
post-operative pain was treated with incremental 0.5mgkg−1
tramadol as needed and those having Aldrete score of 9
or higher were transferred to the ward. Sore throat was
definedasconstantpainonthroat.Presenceof
postopera-tivesorethroatatthe 2ndand24hwasquestionedbyan
anesthesiaresidentblindedtogroupassignment.24hdata
wasobtainedwithphoneinterview.
Poweranalysis
The hypothesis of our study was that occupational
expe-riencewouldchange initial LMcp.Majoroutcome variable
wasinitialLMcp.Usingthedataofapreviousstudy7forLM
intracuffpressure(112±59cmH2O),inordertodetect25%
differenceamongthegroups,atanalphaerrorlevelof0.05
andapowerof90%,wehavecalculatedthatthereshouldbe
atleast59patientspergroup.60patientspergroupwere
includedinthestudytoovercomeanydataloss.
Statisticalanalysis
We analyzed the data with SPSS version 17 (SPSS Inc.,
Chicago, IL). The normality of the data distribution was
assessedwithKolmogorov---Smirnovtest.Nominaldatawere
analyzedwiththeOne-WayANOVAtest.Nonparametricdata
amongthe groupswere analyzedusingKruskal---Wallisand
Mann---WhitneyUtest.Thepharyngolaryngealcomplications
werecomparedamongthegroupsusingthechi-squaretest.
p-Valuelessthan0.05wasconsideredsignificant.
Results
Allpatientsand anesthesiateamworkershave completed
thestudy.Demographicdataofthepatientsanddurations
ofoperationsweresimilar(p>0.05)andshowninTable1.
Occupational experience was found to be 4.2±3.9;
3.3±1.1and6.6±3.8yearsforanesthesiaspecialists,
resi-dentsandtechniciansrespectively.
Mean initial LMcp were 101.2±14.0 for Group S,
104.3±20.5forGroupRand105.2±18.4cmH2OforGroup
T.ThedifferencesamongmeanLMcpofgroupswasnot
sig-nificant(p>0.05).
MeanLMcpvaluesobtainedattheinitialcuffinflationand
thenexttimeintervalshavebeenshowninTables2and3.
Therewas nostatistical differenceamongLMcp valuesin
theinter-groupanalysis(p>0.05).
Overall preoperative complication (sore throat,
laryn-gospasmandbloodstainonLM)ratewas13.3%(24patients).
Numberofpatientshavingpreoperativepharyngolaryngeal
adverse events were 6 (10%), 9 (15%) and 9 (15%) within
GroupsS, RandT respectively. Therewasnostatistically
significant difference among the groups with regard to
pharyngolaryngealadverseeventrate(p>0.05)(Table4).
Discussion
WehavefoundthatmeasuredmeaninitialLMcpwerehigher
thansuggested valuesinallgroups. Resultsofthepresent
studyhave shownthat experienceoftheanesthesiateam
practitionersdoesnothaveaninfluenceonaccurate
deter-mination of LMcp and related pharyngolaryngeal adverse
eventincidences.IthasalsobeenfoundthatLMcphadarise
trendtoexceednormallimitsalthoughtheywereadjusted
tonormallimitsinpredeterminedtimeintervals.
Anesthesiologistsareasubgroupofhealthcareproviders
whouseLMintheirdailyroutinepractiseandtheyarevery
familiarwiththeuseofit.Theothermedicalpersonnelsuch
asemergencydepartmentphysicians,paramedicsornurses
whocareemergencyvictimsattheambulancealsouseLM,
LMFastrach for their patients.3---5,12 Rare complications of
LMuseareespeciallypossibleinthesettingofemergency
airwaycareof thepatientswhere theprimaryconcernof
healthcareprovidersistokeepanopenairwayandcontinue
oxygenation.3---5,12
Hyperinflation of LMc may be harmful because of the
exertion of high pressures on pharyngeal and laryngeal
structures.13 HighLMcpcanleadtodecreaseinpharyngeal
mucosalcapillaryperfusionpressure.8,14 Ulrich-Puretal.14
emphasizedthatusingatmaximalcuffvolumesaccordingto
Table1 Demographicdataanddurationsofoperationsinthegroups.
GroupS GroupR GroupT p
Age(year) 48.8±15.8 46.3±15.1 48.5±14.0 0.604 Weight(kg) 72.2±15.6 72.6±16.1 74.5±12.9 0.671 Operationduration(min) 53.7±19.0 54.2±26.6 51.0±18.0 0.678 Sex(F/M) 24/36 19/41 23/37 0.605
Table2 MeasuredLMcpat15minintervals(cmH2O),(mean±SD).
Measurementepisode GroupS GroupR GroupT p
I 101.2±14.0 104.3±20.5 105.2±18.4 0.426 II 83.9±15.8 87.9±15.1 84.5±18.1 0.361 III 80.7±13.9 80.1±15.5 83.8±15.9 0.390 IV 77.5±14.2 78.4±17.4 75.6±12.9 0.669 V 76.5±14.4 71.5±12.3 76.0±17.9 0.375
Table3 Supramaximal,normalLMcpandoverallcomplicationrateswithinthegroups.
Group LMcp>120cmH2O,n(%) LMcp<60cmH2O,n(%) Complicationrate,n(%)
GroupS 29(48.3%) 10(16.7%), 6(10.0%) GroupR 29(48.3%) 9(15.0%) 9(15.0%) GroupT 25(41.7%) 7(11.7%) 9(15.0%) All 83(46.1%) 26(14.4%) 24(13.3%)
Table4 Ratesofintubationattempt,sorethroat,laryngospasmandbloodstainonLMaccordingtothegroups.
Intubationattempt1/2/3(n) Sorethroat Laryngospasm(n,%) BloodstainonLM(n,%) 2h(n,%) 24h(n,%)
GroupS 56/4/0 2,(3.3%) 2,(3.3%) 2,(3.3%) 0,(0%) GroupR 44/13/3 4,(6.7%) 3,(5%) 0,(0%) 3,(5%) GroupT 50/8/2 7,(11.7%) 2,(3.3%) 0,(0%) 2,(3.3%)
LMProSealinducedsignificantlyhigherpharyngealpressures comparedwithallotherairwaydevicessuchasCombitube, endotrachealtubeandtheEasyTube.Theydeterminedthat, using a pharyngeal cuff volume of 40mL, the Intubating LaryngealMaskAirwayfollowedbytheLaryngealMask Air-wayexerted significantly higher pressures compared with theotherdevices.14
Although very rare, it is also possible nerve damages
to occur as a result of pressure related trauma to the
surrounding tissues.9,10,15 Also, hyperinflation of LMc can
increaseleakagearoundtheLMc.16 In addition,high LMcp
canleadtoincreasedpostoperativepharyngolaryngeal
mor-bidity.Overinflationof laryngealmaskespeciallymaylead
topostoperativesorethroatrate.7,17,18ManufacturerofLM
recommendsthatLMcpshouldnotexceed60cmH2O.7,11,17,18
Seet et al.7 has recently demonstrated that intracuff
pressureexceeds normallimitswhen usedfor anesthesia.
Asaresultoftheirstudy theyhadrecommendedthe
rou-tineuse of pressuremanometerswhen LM is firstplaced.
Schlossetal.18 evaluated theincidence of LM
hyperinfla-tionandtheydetermined that53% ofsubjects hadan LM
intracuffpressureexceeds≥60cmH2O.Theyconcludedthat
significant percentageof patients have an intracuff
pres-sure greater thanthegenerallyrecommendedupper limit
of60cmH2O.
However,LMcpadjustedbyworkersofvariousexperience
andteampositionhavenotbeenevaluatedinprevious
stud-ies.Ourfindingssuggestthatintracuffpressureoccursasan
independentfactorofexperience.
Ontheotherhand,anesthesiaresidents,specialistsand
intensivecarephysicianshavebeendemonstratedthatthey
adjustendotracheal tube cuffpressuresimproperlyin the
previousstudies.19---22Galinskietal.19havestudiedthe
inci-denceofexcessiveintracuffpressureintheout-of-hospital
settingandtheyfoundoutthatmostofcuffpressureswere
exceedingthenormallimitsrequiringcorrection.Theyhave
recommended frequent measurement and adjustment of
cuffpressureasnecessary.Inasimulationmodel,Hoffman
et al.20 had determined that physicians working on the
emergency service of a university werecausing toexcess
pressures,higherthan120cmH2Oand,concluded,similarly
occupational expertise. Endotracheal tube cuff pressure
without proper adjustment may exceed recommended
limits, which can place the patients unwanted risks.21
Ganner21 concludedthatcuffpressures aretoohigh using
theminimalocclusiontechniqueandthecuffsareproneto
leaking.Fernandezetal.22 comparedthe accuracyof this
methodwithinstrumentalintracuffpressuremeasurement
in tracheal model tests by 20 members of our ICU team
and they conclude that precise intracuff pressure
mea-surement is mandatoryto prevent complications of
over-or underinflation. Morriset al.23 determine the incidence
of endotracheal and tracheotomy tubescuff overinflation
and they concluded that despite increasing awareness
amongintensivistsandrespiratorytherapists,theincidence
of tracheal tube overinflation remains high, with both
endotrachealandtracheotomytubes.
Similarly that Parwani etal.24 determine the abilityof
paramedicsto inflateendotracheal tube cuffs within safe
pressurelimitsaswellastoestimatethepressureof
pre-viouslyinflatedendotrachealtubecuffsbypalpationofthe
pilotballoon.Theyconcludedthat,participantswereunable
toinflateendotrachealtubecufftosafepressuresandwere
unabletoidentify endotracheal tube cuffs withexcessive
intracuffpressureby palpation.Theyemphasizedthat
cli-niciansshouldconsiderusing devicessuchasmanometers
to facilitate safe inflation and accurate measurement of
endotrachealtubecuffpressure.24
Inthisstudy,ourresultswereinconcordancewiththose
of previous studies sothat users might achieve incorrect
LMcpduringtheirpractice.Inaddition,wedeterminedthat
anesthesiateammembersofvariousoccupationalexpertise
werenotdifferentfromeachotherintermsofnormalLMcp
determinationsinceonly14.4%ofthecaseshadLMcplower
than60cmH2O.
LMcp canincreasetohighpressurevaluesdueto
diffu-sionofN2Ointothecuffevenifitwasaccuratelyinflatedat
thefirstattemptoradjustedtonormallimitsatthe
begin-ningofanesthesiapractise.Duringgeneralanesthesiawith
LM,asignificantincreaseincuffpressureduetodiffusionof
nitrousoxidethroughthecuffwalloccurs.7,25---27Inprevious
studies, Ouellette25 demonstrated that there wasa
grad-ualincreaseinthecuffpressurewellovera3-hourperiod
duringnitrousoxideandoxygenanesthesia. Mainoetal.26
investigated LMcp changes during nitrous oxide exposure
andtheydemonstratedthatLMcpincreaseswithin5minof
nitrousoxideexposurewere>250%in theLM-Classic.
Sim-ilarlyvanZundertetal.27studiedcuff-pressurechangesin
the LM-Classicand theydemonstratedthat during nitrous
oxideanesthesia, cuffpressureincreases.Theyconcluded
thatcuffpressuresshouldbemonitoredduringnitrousoxide
anesthesiabecauseoflesspostoperativesorethroatwhen
LM-Classicisused.
Burgardetal.28 studiedtheeffectofLMcponthe
inci-denceofpostoperativesore throat.They determinedthat
significantincreaseincuffpressureisseenduringthefirst
60min.Andtheyconcludedthatpostoperativesorethroat
can be reduced when cuffpressure is continuously
moni-toredandkeptonlow-pressurevalues.
Results ofourstudy have alsodemonstratedthatLMcp
continuetoincreaseandexceednormallimitsevenifitwas
adjusted tonormalrangeat thefirstplacement.The
rea-sonofthisobservationisintraoperativeN2Ouse.Thus,we
furtherextendtheearlierrecommendationof Seetetal.7
andadviseperiodicmeasurementsofLMcpintraoperatively.
The sore throat incidence found in our study is
simi-larwiththe previous studyof Seet etal.7 This resultcan
beattributedtoserialLMcp adjustmentswhenit exceeds
60cmH2O.
Therearecertainlimitationsofthisstudy.Oneofthe
lim-itationsisthefactthatalltheparticipantsinthestudyknew
thestudysubject,butitisimpossibletoconductsuchastudy
indouble-blind fashion. Allthe participants learnedwhat
wastheLMcpvaluewhentheyinflatetheLMc.Althoughit
canbespeculatedthatthisknowledgecouldeffectthenext
LMcinflationofthesamepractitioner,allparticipantswere
allowedonlyonetrialinthesameday.Whenweinvestigate
theresults,we haveobservedthateachgrouphadsimilar
valuesatallmeasurementintervals,thussuchanaffectdid
notoccurasexpected.
Inconclusion,wehavefoundthatoptimalLMcpcannot
beproperlydeterminedwithoutuseofpressuremanometers
andthisskillis independentfrompractitioner’sexpertise.
Asthese manometersarecheapand easy touse,we
rec-ommendroutineuseofthembothattheinitialplacement
ofLMandduringthesurgeryforLMcpadjustmentfortheir
contributiontodecreaseadverselaryngopharyngealadverse
eventrate.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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