REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
OfficialPublicationoftheBrazilianSocietyofAnesthesiologywww.sba.com.br
SPECIAL
ARTICLE
Preoperative
evaluation
of
the
patient
with
pulmonary
disease
夽
Luiza
Helena
Degani-Costa
a,b,
Sonia
Maria
Faresin
a,
Luiz
Fernando
dos
Reis
Falcão
a,b,∗aEscolaPaulistadeMedicina,UniversidadeFederaldeSãoPaulo,SãoPaulo,SP,Brazil bMassachusettsGeneralHospital,HarvardMedicalSchool,MA,USA
Received14September2012;accepted19November2012
KEYWORDS Anesthesia; Evaluation; Lung;
Pneumonectomy
Abstract
Backgroundandobjectives: Indailyclinicalpractice,pulmonarycomplicationsrelatedto
sur-gicalprocedurearecommon,increasingthemorbidityandmortalityofpatients.Assessment oftheriskofpulmonarycomplicationsisanimportantstep inthepreoperative evaluation. Thus,wereviewthemostrelevantaspectsofpreoperativeassessmentofthepatientwithlung disease.
Content: Pulmonary risk stratification depends on clinical symptomsand patient’s physical
status.Age,preexistingrespiratorydiseases,nutritionalstatus,andcontinuedmedical treat-mentareusuallymoreimportantthanadditionaltests.Pulmonaryfunctiontestsareofgreat relevancewhenhighabdominalorthoracicproceduresarescheduled,particularlywhenlung resectionareconsidered.
Conclusion:Understanding theperioperativeevaluationofthepotential riskfor developing
pulmonarycomplicationallowsthemedicalteamtochoosetheadequateanesthetictechnique andsurgicalandclinicalcarerequiredbyeachpatient,therebyreducingadverserespiratory outcomes.
©2013SociedadeBrasileiradeAnestesiologia.PublishedbyElsevier EditoraLtda.Allrights reserved.
Introduction
Postoperative complication is the occurrence of an unex-pectedchangethataffectsthepatient’swelfareordeviates from the expected outcome after a surgical procedure. Postoperativepulmonarycomplications(PPCs)occurwithin
夽 Studycenter:DepartmentofPulmonologyandAnesthesiology,
PainandIntensiveCare,EscolaPaulistadeMedicina---Universidade FederaldeSãoPaulo.
∗Correspondingauthor.
E-mail:luizfernandofalcao@gmail.com(L.F.dosReisFalcão).
thirtydaysafter thesurgical procedure, altertheclinical
pictureofthepatient,andmayrequiredrugtherapy
inter-vention.
It is known that most surgical procedures is related
topulmonary functionchanges,1---3 usuallymild or
moder-ate,butoccasionallysevere.4Pulmonarycomplicationsare
importantcausesofperioperativemorbidity.5,6Ithasbeen
reportedin1%---2%ofallpatientsundergoingminoror
mid-size surgery and may reach 10%---20% in those undergoing
upper abdominalor thoracic surgery.5,6 There are reports
thatacutelunginjury(ALI)occurredin3%ofpatientsafter
electivesurgery,amajorcauseofpostoperativerespiratory
failure.4
Pulmonarycomplicationsmaybeclassifiedaccordingto
itspotentialfordeathasmajor(respiratoryfailure,
mechan-icalventilationand/or intubationfor morethan 48h, and
pneumonia)orminor(purulenttracheobronchitis,
atelecta-siswithclinicalandbronchospasm).
Theachievementofadequatepreoperativeevaluationof
pulmonaryriskallowstheinstitutionofmeasurestoreduce
suchcomplicationsandconsequentlytheperioperative
mor-bidityandhospitalstay.Asarule,itisrecommendedthat
patientswithpreviousrespiratorydiseaseareevaluatedby
apulmonologist.
Several predictors were identified for PPCs and are
related toprevious clinical conditions and characteristics
of the anesthetic-surgical procedure. Age over 60 years,
pre-existinglung disease,smoking, andprevious
spiromet-ricchanges(FEV1<1L)areassociatedwithhighpulmonary
risk.Similarly,durationofanesthesia(>3h),headandneck
surgeries,chest andupperabdomen surgeries,anduseof
nasogastric tube preoperatively increase the incidenceof
respiratoryevents.
Because pulmonary complications are associated with
worsening of the postoperative outcome,7 in this article
we willdiscuss themain clinical factorsand strategiesin
ordertoreduceperioperative pulmonary complicationsof
thesurgicalpatient.
Preoperative
evaluation
of
the
candidate
for
general
surgical
procedures
There are novalidated modelsof pulmonary risk
stratifi-cation.Wepresent hereasuggestionforinitial evaluation
based on the guidelines of the American College of
Physicians8 and on the outpatient experience of
preop-erative evaluation of the disciplines of Pneumology and
Anesthesiology, Pain and Intensive Care Medicine of the
EscolaPaulistadeMedicina(EPM-Unifesp).
All assessment depends crucially on the history and
physicalexamination, consideringtheadditionaltests
ret-rospectively,whichwillberequestedinatargetedmanner.
Riskfactorswillbediscussedinasystematicwaybelow.
Surgery-relatedaspects
Usually, in surgical procedures with no cavity opening or
airwaymanipulation, therisk for PPCs is low.Intra-cavity
proceduresinducemajorchangesintherespiratorysystem
comparedtoperipheralprocedures.Thoracicand
abdomi-nalsurgeries(especiallywithupperabdomenincisions)are
thenon-cardiacprocedureswithahigherriskofpulmonary
complications.8---10Thelaparoscopicapproachmayminimize
thesechanges,butitdoesnoteliminatetheriskofPPCs.
HeartsurgeryhasapeculiarriskforPPCs.Inmyocardial
revascularization,dissectionoftheinternalthoracicartery
may predispose to temporary or perennial phrenic nerve
injury.Aftercardiopulmonarybypass(CPB),pulmonary
dys-functioniswelldescribedbutpoorlyunderstood.11Although
theincidenceofacuterespiratorydistresssyndrome(ARDS)
after CPB is low (<2%), mortality is high (>50%).12 During
CPB, both lungs are kept collapsed. If measures are not
taken immediately after the end of CPB, the lungs will
be slowly recruited and more than half of the lungs can
remainatelectaticonetotwodaysaftersurgery,with
intra-pulmonaryshuntaround20%---30%ofcardiacoutput.13 CPB
durationis directlyrelatedtotheincidenceof
postopera-tiverespiratorycomplications,14 aswellastheintensityof
pulmonaryinterstitialedema.15 Severepulmonarychanges
withinterstitial and alveolar edema may occur when the
periodofCPBexceed150min.14
A surgical time greater than 3h is an independent
riskfactor for theoccurrence ofpostoperative pulmonary
complications.Emergencysurgeriesarealsoassociatedwith
higher incidence of PPCs, as there is no time to
stabi-lizethe underlying diseases and properly prepare for the
procedure.8
Anesthesia-relatedaspects
Generalanesthesiais reportedin severalstudies asa risk
factorforPPCs.The useofneuromuscularblockingagents
foradequatesurgicalrelaxationmaybeanimportantcause
of respiratory complications and development of
postop-erativehypoxemia. This is primarily due to the presence
of residual neuromuscular block.16 The use of long-term
neuromuscular blocking increases this effect by
depress-ing the cough reflex and allowing the microaspiration of
gastriccontents.17Prolongedexposuretogeneral
anesthet-icsmay promote changes in gas exchange andtemporary
immunosuppression due to reduced production of
surfac-tant, increased alveolar---capillary permeability, impaired
alveolarmacrophagefunction,andslowmucociliary
clear-ance.
Duringgeneralanesthesia,thesupinepositionand
inva-siveventilationpromote changesinventilatorymechanics
because it impairs the diaphragm action, resulting in
reduced volumes and lung capacities. As a result, up
to90% of anesthetized patients present withatelectasis,
whichpromotedisturbancesinventilation-perfusion(VA/Q),
impairlung compliance, and explain the onset of
hypox-emia. Persistent atelectasis postoperatively, associated
withtransientrespiratorymuscledysfunctionandeventual
ventilation-dependentpainafterthoracicand/orabdominal
proceduresresultinincreasedworkofbreathing11(Table1).
In regional anesthesia, the ventilatory effects will
dependonthetypeandextentofmotorblockade.In
epidu-ralorsubarachnoidextensiveanesthesia,withtheblockade
of basic thoracic segments, there is a reduction in
inspi-ratory capacity and expiratory reserve volume from 20%
to 0%.18 The diaphragmatic function, however, is usually
spared,evenincasesofinadvertentextensionofneuraxial
blocktocervicallevels.19Usually,gasexchangeisminimally
alteredbyregionalanesthesia.
Thus,bloodoxygenationandcarbondioxideelimination
duringepidural and spinal anesthesia arepreserved. This
corroborates the fact that there is a reduction in
func-tionalresidualcapacityandchangeintheratioVA/Qduring
epiduralanesthesia.Exceptionoccurswithmorbidlyobese
patientsinwhichblockadeoftheabdominalmusclescauses
areductionofupto25%inforcedexpiratoryvolumeinthe
firstsecond(FEV1)andforcedvitalcapacity(FVC),in
addi-tiontointerferingwiththe abilitytocough andeliminate
Table1 Effectsofanesthesiaonrespiratorysystem. 1 Lungparenchyma
Decreasedlungvolumeandvitalcapacity Increasedclosingvolume
Decreasedlungcompliance Increasedventilatorywork 2 Airways
Bronchodilation (inhaledanesthetics) Bronchoconstriction
Decreasedmucociliaryclearance 3 Ventilatorycontrol
Reducedventilatoryresponsetohypercapnia, hypoxia,andacidosis
4 Pulmonarycirculation
Reducedreflexvasoconstrictiontohypoxia (inhalationanesthetics)
5 Gasexchange
Increasedalveolar---arterialO2gradientsecondaryto
changeinVA/Qratio
6 Immunefunction
Decreasedbactericidalactivityofalveolarand bronchialmacrophages
Increasedreleaseofproinflammatorycytokines
additionaladvantagesofreducingtheneedforopioidsand contributestoadequatepostoperativeanalgesia.
Interscalene brachial plexus block is often associated with ipsilateral phrenic nerve block21,22 due to cephalad
spreadofanesthesiaandthenervebundleproximity,which
originates in the cervical roots C3---C5. After interscalene
block,theincidenceofhemidiaphragmaticparalysisreaches
100%.21,23---26Thus,changesin lungmechanicsoccur,which
arepotentiallyharmfultopatientswithlimitedrespiratory
reserve. Reducingthe volumeof localanesthetic from20
to5mLthroughbrachialplexusblockguidedbyultrasound
loweredtheincidenceofdiaphragmaticparalysisfrom100%
to45%.27
In healthy patients,diaphragmatic paralysis associated
withbrachial plexus block usually has nosymptoms. This
block,however,isnotrecommendedinpatientswithsevere
pulmonarydisease.28UrmeyandMcDonald23 contraindicate
interscalene block in patients who cannot tolerate 25%
reductioninlungfunction.
Altintas et al.29 reported that interscalene block with
bupivacaineis associatedwithagreater decreaseofFVC,
FEV1, andpeak expiratory flow (PEF)than thosefound in
patientsanesthetizedwithropivacaine.Regarding
analge-sia, equipotent doses of ropivacaine produces less motor
blockandgreaterabilitytoblockadetheA-deltaandCfibers
thanbupivacaine.30
Patient-relatedaspects
Advancedageisassociatedwithincreasedriskof
develop-ingPPCs, evenwhen adjusted forcomorbidities. This risk
increases significantly with each decade of life after 60
years.8 The partial or total dependence toperform daily
andinstrumentalactivitiesisalsoassociatedwithincreased
riskofPPCs.8
Cigarettesmokingisanindependentrisk factorfor the
occurrenceofPPCs,evenwithoutconcomitantchroniclung
disease.The impactis greaterin patientswitha 20
pack-yearsmokinghistoryandthosewhopersistedsmokingbefore
surgery.8,31
Thedetrimentaleffectofsmokinginthepostoperative
periodismultifactorialandinfluencedbycarbonmonoxide,
nicotine,andotherelementscapableofinducing
inflamma-tion and oxidative stress. The proinflammatory effects of
cigarette smokeincreasesthe incidenceof cardiovascular
andinfectiouscomplicationsandhindersthesurgicalwound
healing,inadditiontobeingassociatedwithlongerhospital
andintensivecareunitstays.32
Patients with BMI≥40kgm−2 have 30% chance of
developing atelectasis and/or pneumonia after
abdomi-nal surgery.Additionally,thesepatientshave anincreased
risk of thromboembolism and wound infection compared
tonormalindividuals.33 Similarly,patientswhoevolvewith
acuteweightlossand/ormalnutritionwith
hypoalbumine-mia(serumalbumin<3.5gL−1)alsohaveahigherincidence
ofPPCs.8
Patients with preexisting chronic lung disease, such
as chronic obstructive pulmonary disease (COPD), even
clinicallystableandwithcontrolleddisease,have
substan-tiallyincreasedriskofPPCs. Airwaymanagementinthese
patients maylead toexacerbationofbronchial
inflamma-tion with worsening of hyperactivity and increased risk
of bronchospasm. Airway chronic bacterial colonization
associatedwithtemporary immunosuppressioninduced by
surgicalprocedureandincreasedworkofbreathingalso
con-tributes toincreasecomplications.32 Therisk andseverity
of postoperative complications aregenerally proportional
to the degree of clinical impairment and preoperative
spirometry (FEV1----moderate ifbetween 50% and 80% and
severeif<50%).Prognosisisworseinpatientswhopresent
with pulmonary hypertension and need for home oxygen
therapy.34,35
Althoughrestrictivelungdiseasesappeartobeassociated
withadverserespiratoryevents,theliteraturestillpresents
controversial results. General anesthesia and
mechani-cal ventilation may increase the risk of exacerbating the
inflammatoryprocessofparenchymalfibroticdiseasesand
promotetheadultrespiratorydistresssyndrome.36
Similarly,thereisadecreaseofupto60%ofspirometric
variablesinscoliosiscorrectionsurgery,andmanyofthese
patientsalreadyhavesevererestrictivelungdisease,which
contributes togreater delay in extubation. The peak fall
inlung volumesoccursonthethirdday aftersurgery,and
recoverytobaselinelevelsmaytakeuptotwomonths.37
Additionallytoidentifyingthepresenceofchroniclung
diseases,itisalsonecessarytoassessthedegreeof
symp-tomcontrolwiththespecifictreatmentusedatthattime.
Patients often tend to overestimate their lung condition,
soitisrecommendedthatthephysicianactivelyaskabout
respiratorysymptoms,preferablywiththeuseof
standard-izedquestionnaires.
Obstructivesleepapnea syndrome(OSAS) is present in
upto22%oftheadultpopulationundergoingsurgical
treat-ment, but almost 70% of them have nodiagnosis prior to
Directed history and physical examination
Preoperative screening for OSAS (STOPBang, Berlin or ASA)
+
Low risk OSAS High risk OSAS Patient diagnosed with OSAS
Proceed to surgery with the usual
perioperative care Identify the patient with wristband
Intraoperative management • Consider regional anesthesia with minimal sedation.
• Prepare for difficult airway. Consider CPAP and raise headboard to 25° to increase FRC; use of drugs with short duration of action.
• Consider invasive monitoring for respiratory and hemodynamic management. • Extubation with the patient fully awake and after neuromuscular blockade reversal.
Anesthesia recovery management • Careful observation of oxygen saturation and hemodynamic monitoring.
• Observe headboard elevation to 30° and/or lateral position for at least two hours in most patients. • Consider non-opioid analgesics and regional anesthesia. Use of opioid with discretion.
• Early use of CPAP in case of desaturation.
In-hospital management
• Monitor the patient at the appropriate hospital site that can provide continuous oxygen monitoring. • Use of CPAP if previously diagnosed with OSAS or on CPAP therapy preoperatively.
Management for hospital discharge • Follow-up with sleep expert for polysomnography, diagnostic, and treatment.
Figure1 SuggestedstepsformanagementofOSApatientsundergoingelectivesurgery.
ofsymptoms,suchassnoring,episodesofapneaobserved
by the caregiver, and non-restorative sleep with
exces-sivedaytimesleepinessshouldberoutinelyincludedinthe
preoperativemedicalhistory.Theobservedcharacteristics
predisposing to the existence of OSAS include male
gen-der,ageover50years,BMI>30kgm−2,neckcircumference
>40cm, deviated septum, tonsillar hypertrophy,
laryngo-malacia, tracheomalacia, Down syndrome, micrognathia,
achondroplasia, acromegaly, and macroglossia. There are
validatedquestionnairestoscreenfor OSASinthe
periop-erativeperiod,suchastheBerlinquestionnaire,39ASAOSA
scoringchecklist,40andSTOP-Bang41(Table2).Fig.1shows
thestepssuggestedformanagingpatientswithOSAS
under-goingelectivesurgery.42
On the first postoperative day, there is fragmentation
anddecreasedtotalsleeptime,withsuppressedREMsleep.
In subsequent days, REM sleep rebound and the
conse-quentworseningofsleepapneahavebeenassociatedwith
theoccurrence of PPCs andcardiovascular complications.
Theuseofsedativesandanalgesics(especiallyopioidsand
benzodiazepines) also contributes by decreasing
pharyn-geal tone. The presence of OSAS increases the length of
stayandthechancesofhypoxemiaandreintubationinthe
postoperativeperiod,besidesbeingassociatedwithgreater
incidence of arrhythmias, acute coronary syndrome, and
suddendeath.42
Patientswithclinicallycontrolleddiseases(physical
sta-tusPII) are knowntohave lowerperioperative mortality
(0.2%).8 Thus,patients withinadequateclinical controlof
symptoms(P IIIandIV)mustfirstreceivemaximized
ther-apybeforeundergoinganesthesiaandsurgicalprocedures,
Table2 STOP-BangscoreusedasOSASscreeningin preop-erativeevaluation.
Analyzedvariable Questiontobeasked/examination findings
S Snoring DoyouSnoreLoudly?Louderthan talkingorloudenoughtobeheard throughacloseddoor?
T Tiredness DoyouoftenfeelTired?Doyou sleepduringthedaytime? O Observedapnea Hasanyoneobservedyoustop
breathingduringsleep?
P Pressure Doyouhavehighbloodpressure? B BMI BMI>35kgm−2
A Age Over50years N Neck Circumference>40cm G Gender Male
HighriskforOSAS:≥3positiveresponses.
LowriskforOSAS:<3positiveresponses.
Chronicalcoholismwithmorethan60gdia−1ethanol con-sumption increases up to twice the risk of perioperative acutelunginjuryincandidatesforlungresectionsurgery,43
inadditiontopredisposingtoinfectionsandbleeding.Acute
sensorychanges,delirium,previousstroke,andchronicuse
ofcorticosteroidsarealsoindependentriskfactorsforPPCs.
Roleofadditionalmedicaltestsinpulmonaryrisk evaluation
Medicalhistoryandphysicalexaminationareinmostcases
sufficienttodeterminethepulmonaryriskinvolvedin
gen-eralsurgery.Bloodtests,chestX-rayandpulmonaryfunction
testshouldonlybeorderedwhentheresultsactuallyinvolve
changing the strategy planned for the initial evaluation.
Preoperative arterial blood gases should not be required
routinely,exceptinpatientswithchroniclungdiseaseand
moderatetosevereairwayobstructiononspirometry.
Multicenterprospectivestudiesshowedthatureadosage
above 21mgdL−1 and serum albumin below 3.5gdL−1
werepredictorsofPPCs,particularlypneumoniaandacute
respiratory failure in postoperative noncardiac surgery.8
Perioperative mortality was also higher in patients with
serumcreatinine greaterthan 1.5gdL−1,duetoboth
pul-monaryandinfectiousandcardiovascularandhemorrhagic
adverseevents.44
AlthoughchestX-rayisfrequentlyorderedinthe
preop-erativeevaluation, itsimportanceis questioned.In up to
23%ofthesetests,anabnormalfindingisseen,butinonly
0.1%---3%ofcases,thepre-establishedmedicalapproachis
changed.45 Chest X-rayis moreimportantinpatients with
prior cardiopulmonary disease, those older than 40 years
orwhowillundergomedium andmajorsurgeries,
particu-larlythoracicandabdominalorsurgicalcorrectionofaortic
aneurysm.46
Among the recognized tests to assess lung function,
spirometryisuniversallyknownandmostrequestedduring
preoperative evaluation. However, as a predictor of
pul-monaryadverseeventsinthepostoperativeperiod,itisnot
asgoodastheclinicalevaluation.Itsuseinintra-abdominal
and thoracic procedures without pulmonary resection has
been considered in thefollowing situations: patientswith
knownchroniclungdisease,smokersorexposedtoinhalants
longenoughtocausestructurallunginjury,andthosewith
chronic respiratory symptoms or findings on physical or
radiological examination suggestive of chronic pulmonary
disease.47
Othersituations inwhich spirometryis consideredare:
candidatesforbariatricsurgery,patientswithkyphoscoliosis
undergoinggeneralanesthesia,chroniclungdisease
under-goingneurosurgery,andneuromuscularpatientsundergoing
generalanesthesia.Inpatientswithneuromusculardisease
orkyphoscoliosis,measurementsofmaximalinspiratoryand
expiratorypressuresshouldalsobeordered.FVCbelow40%
of the predicted value and/or maximum pressures below
30cmH2Osignificantlyincreasestheriskofextubation
fail-ureinpostoperativeperiod.45,47 Contrarytowhatoccursin
lungresectionsurgery,therearenoFEV1prohibitivelimits
forperforminggeneralsurgeries.
Inpatientswithpulmonaryarterialhypertension(PAH),
preoperative evaluation should include electrocardiogram
atrestandechocardiography,inadditionto6-minwalktest
(6MWT). The presence of right atrial pressure >77mmHg
atthelasthemodynamicassessmentbeforesurgery,6MWT
distance walked <399m, greater clinical severity, and
emergencysurgeryareindicativeof greaterpostoperative
morbidityandmortality.48Cardiopulmonaryexercisetesting
isroutinelyusedintheclinicalevaluationofpatientswith
PAHtoestablishprognosisandassesstherapeuticresponse.
However,althoughitmayhelptostratifytheseverityof
dis-ease,itsroleinpredictingthesurgicalriskforthesepatients
isstilllimited.
Risk
stratification
of
postoperative
pulmonary
complications
Currently, there are no validated stratification models of
pulmonary risk in generalsurgery. However,theAmerican
CollegeofPhysiciansadoptedsomescalesforassessingthe
riskof specificrespiratorycomplications,9,10 suchasacute
respiratoryfailure(Table3)andpneumonia (Table4).The
AmericanSociety ofAnesthesiologistshasdevelopedarisk
scoreforpredictionofrespiratorycomplicationsinpatients
withOSAS40(Table5).
Particularities
of
the
preoperative
evaluation
for
lung
resection
surgery
Thereisaclearassociationbetweentheextentofpulmonary
resectionandperioperativemorbidityandmortality.
Mortal-ityrateafterpneumonectomyisuptotwo-foldhigherthan
thatoflobectomy.Similarly,themortalityratesof
segmen-tectomyandlumpectomyareinferiortothatoflobectomy,
especiallyifperformedbythoracoscopy.49
Unlike general surgery, preoperative evaluation of
patientsscheduledforpulmonaryresectionrequires
spirom-etry testing and, if necessary, cardiopulmonary exercise
testing(CPET).Foracompleteassessment,itisnecessaryto
combinefunctionalimagingdatafromcomputed
tomogra-phy, pulmonary perfusion scintigraphy, and bronchoscopy.
Table3 Riskfactorsforacuterespiratoryfailurein post-operativeperiodofgeneralnon-cardiacsurgery.
Riskfactor Score
Abdominalaorticaneurysmrepair 27
Thoracic 14
Upperabdominal,peripheralorvascular neurosurgery
21
Neck 11
Emergencysurgery 11 Albumin<3.0mgdL−1 9
Plasmaurea>30mgdL−1 8
Totallyorpartlydependentfunctionalstatus 7
COPD 6
Age≥70years 6
Age60---69years 4
Class Score %Risk
1 ≤10 0.5
2 11---19 1.8
3 20---27 4.2
4 28---40 10.1
5 ≥40 26.6
Riskassessmentfor acuterespiratoryfailure inpostoperative generalnon-cardiacsurgery.
stillparticipatesinpulmonary gasexchange,andthefinal calculationshouldbedone toestimatetheresidualvalues ofpulmonaryfunctionafterthescheduledresection.FEV1is thespirometricparameterusedmostoftenforthispurpose, followedbycarbonmonoxide diffusion(DLCO)or maximal oxygenuptake(VO2max)obtainedinCPET.The ppo desig-nation isadded toindicatethat the estimatedparameter refersto the latepostoperative period; i.e., threeto six monthsafterthesurgicalprocedure(FEV1-ppo,DLCO-ppo, andVO2max-ppo).
Thesimplestcalculationusesthenumberoffunctioning lung segments (right upper lobe=3, middle lobe=2, right lowerlobe=5,leftupperlobe=3 oftheupper division+2 ofthelingulaandleftlowerlobe=4)andassumesthatall segmentscontributeequallytogasexchange,whichisrarely trueinunhealthylungs.50 Thismethodisusedtoestimate
thefunctionafterlobectomyandthefollowingformulasmay
beapplied:
Mode 1: ppo value=
preoperative value
T
×R
T=19−numberof obstructedsegments;R=T−numberof
functioningsegmentstoberesected.
Mode2:ppo value=preoperative value×
1−
a
b
a=number of non-obstructed segments to be resected;
b=totalnumberofnon-obstructedsegments.
For pneumonectomy, the calculation should be made
using the results of perfusion scintigraphy or pulmonary
ventilation. Perfusion examination is the most commonly
used method for this purpose. In this case, the formula
Table4 Riskfactorsforpostoperativepneumoniain gen-eralnon-cardiacsurgery.
Riskfactor Score
Typeofsurgery
Abdominalaorticaneurysmrepair 15
Highthoracic 14
Highabdominal 10 Neckorneurosurgery 08
Vascular 03
Age(years)
≥80 17
70---79 13
60---69 09
50---59 04
Functionalstatus
Totallydependent 10 Partiallydependent 6
Weightlossover10%inthelast6months 7
COPD 5
Generalanestesia 4
Alteredsensorium 4
Priorstroke 4
Urea(mgdL−1)
<8 4
22---30 2
≥30 3
Bloodtransfusiongreaterthan4units 3
Emergencysurgery 3
Chronicuseofcorticosteroids 3
Smokinginthelastyear 3
Alcoholintake>2dosesintheprevious2weeks 2
Class Score %Risk
1 0---15 0.24
2 16---25 1.2
3 26---40 4.0
4 41---55 9.4
5 >55 15.8
Risk assessmentfor postoperativepneumonia ingeneral non-cardiacsurgery.
used for the calculation is: ppo value=preoperative value×(1−perfusionfractionofthelungtoberesected).
Traditionally,theestimatedpostoperativevaluesofFEV1 and/orDLCOless than30%wereconsidered absolute con-traindicationsfor lungresectionduetothehighincidence of cardiorespiratorycomplications and death in the post-operative period. Likewise, values between 30% and 40% frequentlyimposedmore risksthanthe anticipated bene-fitsofsurgery;therefore,cardiopulmonaryexercisetesting (CPET)ismandatoryinthisgroupofpatients.51
However,theadventofminimallyinvasivesurgical
tech-niques,suchasvideo-assistedthoracic surgery(VATS),and
thepossibilityofperformingviable lungparenchyma
spar-ingresectionshaveallowedpatientswithppoFEV1and/or
DLCO<40% to undergo these procedures with morbidity
Table5 The AmericanSociety ofAnesthesiologistsscore forpostoperativecomplicationassessmentinpatientswith OSAS.
A:Severityofsleepapneabasedonsleepstudy(orclinical
indicatorsifsleepstudynotavailable)
None=0,mild=1,moderate=2,severe=3 Subtract1pointinpatientsusingCPAPorBiPAP Add1pointforpatientswithPaCO2>50mmHg
B:Surgeryandanesthesia
Superficialsurgeryunderlocalanesthesiaorperipheral nerveblock=0
Superficialsurgerywithmoderatesedationorgeneral anesthesiaorperipheralsurgerywithepiduralanesthesia (uptomoderatesedation)=1
Peripheralsurgerywithgeneralanesthesiaorairway surgerywithmoderatesedation=2
Majorsurgeryorairwaysurgerywithgeneral anesthesia=3
C:Requirementforpostoperativeopioids
None=0,loworaldose=1,highoraldoseorparenteral orneuroaxial=3
D:Estimationofperioperativerisk
Globalrisk=Ascore+greaterscoreforBorC Patientswithglobalrisk≥4maybeatincreased
perioperativeriskforOSAS
Patientswithglobalrisk≥5maybeatsignificantly
increasedriskforOSAS
ranging from 1% to 15%, reported in the literature.52---54
Inthese patients,surgery totreat lung cancer in stage I,
evenwithminorresections (sublobar resections) resultin
increasedsurvivalcomparedtopatientswhodidnotundergo
theprocedure.55Moreover,tumorresectioninpatientswith
severeCOPDmayhaveareducedfunctionalimpactintwo
situations:(1)tumorislocatedintheupperlobe,whichis
alsothesiteofmajorinvolvementofcentrilobular
emphy-semaand,therefore,withlessfunctionalloss;(2)ifthereis
thepossibilityofcombiningtumorresectionwithlung
vol-umereductionsurgery,ifthepatientisacandidateforthis
procedure.56---60
Accordingly,it became necessary todevelop abroader
method of preoperative evaluation for lung resection
surgery, allowingrisk stratification less focused onsimple
lungfunctionparametersandmorerelatedtothe
individ-ual’sability toperform hisdaily activities. The flowchart
recently developed and published on the guidelines for
lungcancerfromtheAmericanCollegeofChestPhysicians
(Fig.2)isbasedonthisconcept.61Underthenewguidelines,
patientswith ppoFEV1 and/or DLCO >60% areconsidered
at low risk for surgery, with an estimated mortality rate
<1%,and donot requireadditionalpulmonary evaluation.
PatientswithppoFEV1and/orDLCObetween30%and60%
shouldundergosimpleexercisetolerancetestasascreening
method.Those who reacha walk distance >400m onthe
shuttle walktest or are able toclimb >22m onthe stair
climbing test are also considered at low risk and do not
requireadditionalpulmonaryevaluation.Ontheotherhand,
if these cut-off values are not achieved, CPETshould be
compulsorilyperformedforsurgicalriskstratification.
Like-wise,patientswithppoVEF1and/or DLCO<30% alsohave
absoluteindicationtoperformtheCPET.
Portable spirometry has very limited availability in
clinical practice,butitis an importanttoolfor
preopera-tive evaluationofindividuals scheduled forlung resection
surgery. VO2max values (oxygen uptake at peak exercise)
above20mLkg−1min−1or75%higherthanexpectedensurea
safesurgicalapproach(lowrisk).62Thisvalueindicatesthat
the patient’s functional reserve is sufficient to withstand
thestressofsurgeryandperformdailyactivitiesinthelate
postoperativeperiod.PatientswithVO2maxbetween10and
20mLkg−1min−1 orbetween35% and75%oftheexpected
valueareatmoderateriskforperioperativecomplications,
butthesevaluesarenotprohibitive,providedthatthe
ben-efitofsurgeryisconsideredtooutweightherisks.63 Values
belowmLkg−1min−1or<35%oftheexpectedmeanhighrisk
andaregenerallyconsideredacontraindicationtosurgery
duetothehighmortalityrate(>10%).64
CPETprovidesdataoncardiovascularperformance
dur-ing exercise, which have prognostic importance and may
directlyorindirectlyinfluenceriskstratification.For
exam-ple,thisisthecaseofparameterssuchasaerobicefficiency
(VO2/W), oxygen pulse (VO2/HR), and the ratio
minute-volume/CO2production(VE/VCO2).Basedontheforegoing,
the adoptionof cardiac risk asan indicationfor
perform-ing CPETwasincluded inthe new protocol for functional
assessment of lung resection surgery. Patients with
Tho-racic RevisedCardiacRiskIndex(ThRCRI)65,66≥2,whoare
unabletoclimbtwoflightsof stairsor haveheart disease
requiringmedicationornewlydiagnosed,shouldbeinitially
evaluatedbyacardiologistandundergodiagnostictestsand
treatmentsaccordingtoprotocolsforperioperative
evalu-ationofthecardiologysocieties.Afterthisinitialstep,all
patients considered at high cardiacrisk shouldundergo a
CPET(Fig.2).
Perioperative
strategies
to
reduce
the
risk
of
postoperative
pulmonary
complications
Theultimategoalofpreoperativeevaluationandrisk
assess-mentforPPCsliesintheindividualizationofperioperative
strategiesabletoreducethecalculatedrisk.Insome
high-risk situations without strategies to decrease it, special
attention should be paid to early diagnosis of PPCs, and
aggressive treatment shouldbe done toreduce mortality.
Didactically,wetriedtogroupstrategiesintopreoperative,
intraoperative,andpostoperative.
Preoperativestrategies
Specific therapy should be optimized to ensure that the
patient achieves the best possible clinical and functional
condition. If there is evidence of exacerbations, the use
of corticosteroids aloneor combinedwithantibiotics may
be necessary and,in suchcases, it is recommended that
surgerybepostponedforatleast30daysaftertheprocess
resolution.
Instablepatients,therecommendationisthatthe
medi-cationshouldnotbediscontinuedevenonthedayofsurgery.
Spirometry Cardiac risk
Low or moderate
High*
ppo FEV1 and
DLCO <60% Low risk
p2po FEV1 and DLCO between 30-60%
Stair-climbing test or
shuttle walk test
>22 m or >400 m <22 m or <400 m ppo FEV1 and
DLCO <30%
Cardiopulmonary exercise testing
VO2max <10 ml/kg/min or
<35%
VO2max between 10-20 ml/kg/min or
35-75%
VO2max >20 ml/kg/min or
>75%
Moderate risk High risk
*High cardiac risk: New heart disease
Heart disease requiring medication
ThRCI (Thoracic revised Cardiac Risk Index) ≥2, where: - pneumonectomy: 1.5 points
- DAC: 1.5 tos pon
- previous stroke or TIA: 1.5 points
- creatinina sérica > 2mg/dl: 1 ponto serum creatinine> 2mg/dl: 1 point
Other factors such as comorbidities, age, surgical approach (thoracotomy vs minimally invasive) and center experience
Figure2 Evaluationofthepatientundergoingpulmonaryresection.
and undergoing major or midsize elective surgery, the
hospitalization three to five days before the procedure
maybe beneficialbecause itallows theadministrationof
intravenous corticosteroids and fast action inhaled
bron-chodilatorsona fixed schedule,in additiontorespiratory
therapy. In patients with uncontrolled persistent cough
receiving corticosteroids and bronchodilators, the use of
coughsuppressantsmaybeuseful.
Inthepatientwithbronchialhyperreactivityundergoing
general anesthesia with endotracheal intubation, starting
withsystemicsteroidsorallyfivedaysbeforetheprocedure
isrecommended.Moreover,immediatelybeforesurgery,the
patient should receive short duration inhaled beta-2 and
full doses of anticholinergics associated with intravenous
corticosteroids.67---69
Patientswithlungdiseaseareoftenchronicusersof
cor-ticosteroids,eitherasmaintenanceorprescribedtreatment
at exacerbation times. Thus, those using doses of
pred-nisone>7.5mgorequivalentformorethan30daysor>20mg
for more thantwoweeks in thepast year areconsidered
atriskfordevelopingpostoperativeadrenalinsufficiency.46
Patientstreatedwithradiotherapytothepituitaryregion,
withautoimmunediseasesoraclinicaldiagnosissuggestive
ofadrenalinsufficiency,arealsoconsideredatrisk.Ideally,
theyshouldundergodiagnosticevaluationpriortosurgery;
however,ifthereis notenoughtimefortheinvestigation,
empiricalcorticosteroidsupplementationisrecommended,
dependingonthesizeofsurgery:46
• Mildsurgicalstress:doubleortriplethedailydoseof
cor-ticosteroidsusedforpatientswithapreviousdiagnosisof
adrenal insufficiency or chronic corticosteroid users. In
caseoffasting,prescribehydrocortisone(50mg)
immedi-atelybeforesurgerywith25mgmaintenanceevery12h
forupto24haftertheprocedure.
• Moderate surgical stress: parenteral hydrocortisone
(25mg every 8h), beginning onthe morning of surgery
andwithdosereductionof50%/daypostoperativelyupto
suspensionorachievingtheregulardose.
• High surgical stress: parenteral hydrocortisone (50mg
every6h),beginningonthemorningofsurgeryandwith
dosereductionof50%/daypostoperativelyupto
suspen-sionorachievingtheregulardose.
Cigarettesmokingincreasestheriskofperioperative
car-diacandpulmonarycomplications.Smokingabstinencecan
reducetherateofsuchcomplications.70However,the
pre-operativeperiodof abstinencerequired for thisbenefitis
notestablished.Someexpertssuggestthatabstinencefora
weeks)mayhavean increasedriskof PPCs.The supposed
mechanism for this increased risk is a transient increase
in cough and mucous production after abstinence.
How-ever, thereare severalstudies that found no relationship
betweenincreasedriskandashortperiodofabstinence.71
Recentmeta-analysisconcludedthattheavailableevidence
does notsupport theassociation betweenshort periodof
abstinence and increased postoperative risk.72 In
outpa-tients,smokingcessationis notassociated withincreased
coughorsputumproduction,73andsputumproduction
dur-ingsurgeryisnotincreasedinrecentex-smokers(abstinence
eightweeksbeforesurgery)comparedtothosewho
contin-uedsmoking.74Thereby:(1)thereisnostudyreportingthat
abstinencefromsmokinginashortintervalpreoperatively
significantlyincreasespulmonary risk;(2)meta-analysisof
available studies showedno significant increasedrisk; (3)
thereisnosupportforthesupposedunderlyingmechanism
that contributes to the risk; (4) there is no evidence of
reducedPPCsinsubjectsundergoingsurgeryafteraperiod
offourweeksabstinence.75 Thus, preoperativeevaluation
shouldbe considered an importantmeasure toencourage
smokingcessation,regardlessoftheperiodinwhichithas
beenmade.
Cognitive-behavioral strategies, associated with
spe-cific drugs or not so (nicotine replacement therapy,76
bupropion,76 varenicline77),areeffectiveinsmoking
cessa-tionand maybe used both pre-and postoperatively. The
choiceofdrugtreatmentshouldtakeintoaccount
individ-ual patient contraindications and not be changed by the
typeofsurgery.Nicotinepatchesmaybeusedeveninthe
immediatepostoperativeperiod.46
Respiratoryphysiotherapyiscrucialforreducingtherisk
ofperioperativepulmonarycomplications.Itcanbestarted
beforesurgery and maintained throughout hospitalization
in order to maximize lung function and minimize
respi-ratorysymptoms.Preoperativerespiratory muscletraining
can reduce the incidence of atelectasis and increase by
10%themeanvalueofpostoperativemaximum inspiratory
pressure.78
The strategies that can be appliedby physiotherapists
arevariedandinclude:incentivespirometer,sustaineddeep
breathingexercises, assisted coughing, postural drainage,
percussionandvibration,anduseofintermittent
noninva-siveventilation(CPAPorBiPAP).Meta-analysisshoweda50%
reduction of perioperative complications with the use of
incentivespirometeranddeepbreathingexercises,but so
far,thereisnoevidenceofsuperiorityofonestrategyover
theother.
Intraoperativestrategies
Anesthesia causes respiratory impairment, whether the
patientis maintained on spontaneousor mechanical
ven-tilation.Thisimpairmentpreventstheadequacyofalveolar
ventilationandperfusionand,consequently,blood
oxygen-ation.Animportantfactorforrespiratoryimpairmentduring
generalanesthesiawiththepatientinspontaneous
ventila-tionisthereductionofCO2sensitivitycausedbyinhalational
anesthetics,79barbiturates,80andopioids.81Theresponseis
dosedependentandthereisadirectrelationshipbetween
ventilationreduction andanesthetic depth.This does not
precludetheuseofspontaneousventilationduring
inhala-tionalanesthesiainchildren82andadults,83performedunder
monitoringandappropriateadjustment.
Theuseofneuromuscularblockersforadequatesurgical
relaxation intraoperatively maybe an important cause of
respiratorycomplicationsandonsetofpostoperative
hypox-emia.Thisisprimarilybecauseofthepresenceofresidual
neuromuscularblock.16Thus,theevaluationofpatientswith
the use of quantitative neuromuscular blockade monitors
shouldbeconsidered17,84---88,particularlywhenlong-acting
blockerssuchaspancuroniumareused.
There is evidence that inhaled anesthetics, such as
isoflurane89 andsevoflurane,90 mayreducethe
ventilation-induced lung injury (VILI).Preconditioning withisoflurane
in the lungs and other organs mimics the
cardiopro-tective effect of ischemic preconditioning91 through the
activationofadenosinereceptors92andATP-sensitive
potas-sium channels.93 Isoflurane induces protective effects
during ischemia---reperfusion94 and lung injury induced by
endotoxin95orzymosan.96Therearealsobenefitsin
reduc-ingcytokinereleasecausedbymechanicalventilation,97 in
additiontoaprotectiveeffectagainstlunginjuryby
avoid-ingpro-inflammatoryresponses.89
Balanced anesthesia should be used in patients with
obstructive lung diseases due to the action of inhaled
bronchodilator.Desfluraneshouldbeusedsparinglydueto
the effectof coughing, laryngospasm,bronchospasm, and
bronchialhypersecretion.98.99
In regional anesthesia for upper limb surgery,
inter-scalene brachial plexus block with large volume of local
anestheticshouldbeavoidedinseverechroniclungdisease
patients,asthereisariskofipsilateraldiaphragmatic
paral-ysis. Preferably, plexus block should be performed under
directvisualizationwithultrasoundandminimumlocal
anes-theticvolumes.100
Intheintra-andpostoperativeperiods,fluidreplacement
shouldbemadewithcautionandexcessiveadministration
offluids andpositivefluidbalanceavoided.Theexcessive
intravascularvolumeleadstoextravasationoffluidintothe
interstitiumandpredisposestoacutelunginjuryand
respi-ratoryfailure,101woundinfection,anastomoticdehiscence,
and postoperative ileus. Moreover, positive balance often
generates extubation difficulties, resultingin longer
intu-bation time and ICU stay. Thus, fluid replacement should
preferably be based on macro and micro-hemodynamic
parameters.102
The use ofa nasogastric tube (NGT) increases the risk
ofmicroaspirationsand,consequently,pulmonaryinfections
inthepostoperativeperiod.Thus,itsroutineuseshouldbe
abandoned andthe passageof NGT restricted to patients
withaclearindication.103
Postoperativestrategies
Thedecisiontorequestthatthefirstpost-operativecareof
a patientbe made in theICU dependsonthe size of the
surgery,severityofthepatient’scondition,andriskof
peri-operativecomplications.Thus,therecommendationshould
bemadejudiciouslyfromcarefulpreoperativeevaluation.
Analgesics that depress the respiratory system should
systemicopioidsisknowntoworsentheairwayobstruction
andincreasetheincidenceofpostoperativecomplications.
Therefore, the use of simple analgesics (dipyrone,
para-cetamol)andhormonalornon-hormonalanti-inflammatory
drugs is recommended for cases of mild pain. For
mod-erate to severe pain, ketamine or dexmedetomidine can
reduceopioidrequirements.104Incasesofregional
anesthe-sia,maintainingcathetersforpostoperativelocalanalgesia
isrecommended.
Postoperatively, patients with spontaneous breathing
should beevaluatedregarding the need for supplemental
oxygen by facemask or catheterthrough blood gas
analy-sis and pulse oximetry. Especiallyin patients with COPD,
OSASand/or heartfailure,theuse ofnoninvasive
ventila-tionif respiratorydistress occursmayavoid reintubation.
OSApatientshavehigherriskofdevelopinghypoxemiaand
hypercapnia postoperatively and should be handled with
CPAP routinelyassoon astheyareadmittedtothe ICUor
ward.
Patients on invasive mechanical ventilation should be
immediatelyincluded inweaningprotocolsand,whenever
possible,ventilatedinpressuresupportmode.Deep
seda-tionandanalgesiashouldbeavoided,aimingatscoresof2
or3ontheRamsayscale,andrespectingthesedation
proto-colofdailyinterruption.Respiratorytherapyandendurance
workoutsalsohelptoreducethetimeofintubation.
Except incases of contraindicationdue tothesurgical
procedurenature,thehead shouldbekeptat30◦
inclina-tion.Thismeasurenotonlyhelpspreventairwayobstruction
inpatientswithspontaneousventilation,buthasalsoproven
toreducetheincidenceofventilator-associatedpneumonia.
Conclusions
Preoperativeevaluationofpatientswithrespiratorydiseases
should be made in candidates to elective or emergency
surgery,asthereisthepossibilityofestablishingmeasures
that reduce the risk of complications during intra- and
postoperative periods.In any of these situations, the
ini-tialassessmentisclinical,andcomplementaryexaminations
shouldberequested basedonthisassessment. Inelective
procedure, the goals of preoperative assessment can be
morewidelyattained;namely,clinicalstabilizationoflung
disease,maximizinglungfunction,smokingcessation,and
earlyinstitutionofpreoperativerespiratorytherapy.
Finally, lung disease patients often present withother
comorbidities and should be globally assessed for
cardio-vascular, metabolic, renal, and venous thromboembolism
risks involved in the anesthetic-surgical procedure to be
performed.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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