JPediatr(RioJ).2017;93(4):317---319
www.jped.com.br
EDITORIAL
Sedation
and
subglottic
stenosis
in
critically
ill
children
夽
,
夽夽
Sedac
¸ão
e
estenose
subglótica
em
crianc
¸as
gravemente
doentes
Steven
L.
Shein
a,b,
Alexandre
T.
Rotta
a,b,∗aUHRainbowBabies&Children’sHospital,PediatricCriticalCareMedicine,Cleveland,UnitedStates
bCaseWesternReserveUniversity,SchoolofMedicine,Cleveland,UnitedStates
As mortality rates have decreased over the past few decades,thefocusofcontemporarypediatriccriticalcare hasshiftedtowardminimizinglong-termmorbidity.Children requiring endotrachealintubationand mechanical ventila-tionareatriskforanumberoflastingsequelae,including chronicrespiratoryfailure,neuropathy/myopathy,and cog-nitiveimpairment.1Riskfactorsforindividualcomplications
have been described, andactions toavoid theserisk
fac-tors should be considered. However, avoiding one action
invariablycausesareactionthatmayconferitsownadverse
effects. For example, a dry lung strategy shortens the
duration of mechanical ventilation in the acute
respira-tory distresssyndrome(ARDS), but mayworsenlong-term
neurologicstatus.2,3Alung-protectivestrategymayreduce
ventilator-associated lung injury and the risk of chronic
respiratoryfailure,buttheresultantacidosisandelevated
intrathoracicpressurescanbepoorlytoleratedinchildren
withfluid-refractoryshock,pulmonaryhypertension,and/or
intracranialhypertension.4Whenfacedwithmultiple
ther-apeuticoptions,pediatricintensivistsmustbecognizantof
therisksandbenefitsofallpossiblepaths.
Another risk of endotracheal intubation is the
devel-opment of subglottic stenosis. InvestigatorsfromHospital
de Clínicas de Porto Alegre have established themselves
夽
Please cite this article as:Shein SL, RottaAT. Sedation and subglottic stenosis in critically ill children. J Pediatr (Rio J). 2017;93:317---9.
夽夽
SeepaperbySchweigeretal.inpages351---5.
∗Correspondingauthor.
E-mail:Alexandre.Rotta@UHhospitals.org(A.T.Rotta).
attheforefrontofresearchintothisimportantcondition.
They have previously shown that subglottic stenosis is a
common problem among their intubated patients,
occur-ring in approximately10% of cases.5,6 In this issue of the
JornaldePediatria,theyaimedtotakeanimportantnext
step---identifyingriskfactorsassociatedwiththe
develop-mentofsubglotticstenosis.7Understandingriskfactorsfor
developingsubglotticstenosismayallowareductioninits
occurrence,which mayin turn reduce extubationfailure,
theneed for diagnosticproceduresandtherapeutic
inter-ventions.However,ifrisk factorsareidentified,onemust
becautioustothinkof thepossible reactions,in orderto
avoidthem.
Beforeconsidering anyidentifiedriskfactors,onemust
evaluatethe validity of the study andits applicability to
one’s own patient population. Schweiger et al.7 should
be commended for the several strengths of their
meth-ods, including the subglottic stenosis assessment, which
was prospective and uniformly thorough the study, and
the use of a validated and widely used sedation
assess-mentscore(COMFORT-B).8However,theirsamplesizewas
small (n=36), which limited the power of their
statisti-calanalysis. This smallsample size also likelyinfluenced
thedistributionoftheCOMFORT-Bscores,whichwere
pre-sumablynotnormallydistributed (astheywere evaluated
using a non-parametric test) but were reported in the
styletypicallyusedfornormally-distributeddata(meanand
standarddeviation),whichlimitsourabilitytofully
inter-prettheir findings.We look forwardtotheir futurework,
which will hopefully evaluate for risk factors in a larger
cohort.
http://dx.doi.org/10.1016/j.jped.2017.03.001
318 SheinSL,RottaAT
Thereareseveralfactorsworthconsideringregardingthe
applicability of their findings to your patient population.
First,given that theauthors conclude thatundersedation
isa keyrisk factor for developing subglotticstenosis (see
below), it is important to compare their sedation
prac-ticeswithyour own.The authorsreport thatthe infusion
ratesforfentanyl(2g/kg/h)andmidazolam(0.2mg/kg/h)
werenot titratedto effect,but supplemented asneeded
with‘‘additionaldosesofsedation.’’Thisreactiveprotocol
maylimitthegeneralizabilityoftheirdatatocentersthat
practiceamoreproactivestyle,inwhichinfusionratesare
adjustedandinwhichcomfortlevelsmaybemore
consis-tent.Second, most oftheir cohort(72.2%) wasventilated
throughuncuffedendotrachealtubes.Inthe2010and2015
editions,theAmericanHeartAssociation guidelinesstated
that cuffedendotracheal tubes ‘‘may bepreferable’’ for
situationsthat arecommonly seen in thepediatric
inten-sive care unit (PICU), such as poor lung compliance and
highairwayresistance,anditisourgeneralpracticetouse
cuffedendotracheal tubes in children of all ages.9,10 The
useof cuffedendotracheal tubesisassociated withalow
sideeffectprofile,likelyinfluencedbyrecentimprovements
in cuff design to better fit the pediatric airway and
cre-ateasufficientsealatlowpressures,withminimalpressure
points.11 Regarding subglottic stenosis, thereare possible
benefitsof usingacuffedtube.Foranygivenpatient,the
recommendeddiameterofanuncuffedtube islargerthan
thatrecommendedfor acuffedtube. Largerendotracheal
tubes lead to increased tissue injury, including by direct
mucosalcompression at severalsites along the airwayby
thesideofthe endotrachealtube.12 Trachealdamagecan
also be caused by pressure from the distal edge of the
tubeagainsttheairway.Aproperlyinflatedcuffmaykeep
the edge of the endotracheal tube more centrally
situ-ated within the lumen of the airway and away from the
mucosa.Moreover,theuseofuncuffedtubesoftenprompts
reintubation---duringwhich theedgeof theendotracheal
tube may irritate the pharynx,larynx, and trachea --- for
an increased tube size if a significant leak develops. In
onerandomizedstudy of childrenundergoingsurgery, the
insertionof an uncuffed tube required reintubation for a
properlysized tube in347outof 1127subjects(30.8%),a
significantlyhigherratethanwhatwasobservedwithcuffed
tubeplacement(24/1119[2.1%]).13 Thenumberof
reintu-bations has been previously shown tobe associated with
increasedairwayinjury.14Reintubationduetoanincorrectly
sized uncuffed endotracheal tube wasneeded in the
cur-rentstudycohort(exactnumbernotreported),andtheuse
of cuffed tubes may avoid unnecessary additionalairway
trauma. Finally, it is important to note that the
approxi-mately10%rateofsubglotticstenosisreportedinmultiple
studiesbythisresearchgroupishigherthanthosereported
by other groups (6/215 [2.8%] by Gomes Cordieroet al.,
6/144 [4.2%] by Jorgensen et al.), but this may actually
reflectamoresensitiveandthoroughevaluationratherthan
atrueincreasedlocalincidence.14,15
Those issues notwithstanding, the authors report that
children in their cohort who developed subglottic
steno-sis spent much more time (15.8%) undersedated with a
COMFORT-Bscoreof23---30whencomparedwiththosewho
did not develop subglottic stenosis (3.7%). Taking this at
face value, one could postulate that avoiding periods of
undersedation may reduce the risk of subglottic stenosis.
Butwhatisthereactiontoaimingtoavoidundersedation?
Obviously, it will be a predilection toward oversedation.
Oversedationandincreaseduseofsedative/analgesicdrugs
come with a litany of possible adverse effects. Increased
drugusageisassociatedwithincreasedrisksofdrug
with-drawal syndrome and extubation failure.16,17 Opiates and
benzodiazepineshavebeenassociatedwithdose-and
time-dependent neurodegenerationin pediatricanimal models,
and increased usage of particular drugs may worsen
cog-nitive outcomesin children.18,19 The mostcommonly used
sedative/analgesic drugs can prompt hypotension, which
itself is a risk factor for unfavorable outcomes in many
commonPICUconditions.20,21 Morespecificallytothetopic
athand,theauthorsthemselvesnoteintheirintroduction
that excessive sedation can lead toairway hypoperfusion
andlocalischemia,whichmaythencontributetosubglottic
stenosis.
Sowheredoesthisleavethepracticingpediatric
inten-sivist? As is often the case, we now have more data to
incorporate into our clinical decision-making, but we are
alsoleftwithmanymorequestions.Thesedatasupportthe
intuitivepracticethatkeepingachild‘‘well-sedated’’may
reduce trauma to the airway, but is that worth the risks
of oversedation? What is the impact of sedation on
sub-glottic stenosisin childrenwithaproperlyinflated cuffed
endotrachealtube?Furtherworkisneededtoanswerthese
questionsandmore,andwelookforwardtothenext
contri-butionfromthisprolificresearchgroup.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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