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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2804_Библиотеки_им_академика_М_И_Перельмана
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PerioperativeAnticoagulationandAntithrombotic
Management
GENERALPRINCIPLES
Patients on chronic anticoagulation for AF, VTE, or mechanical heart valves often need to undergo
proceduresthatposeriskofbleeding.
Theindicationforanticoagulationandriskofinterruptionmustbeweighedagainsttheriskofbleeding
oftheprocedure(includingpossibleneuraxialanesthesia).
TREATMENT
Recommendedmanagementvariesaccordingtotheindicationforanticoagulation,medicationused,and
surgicalbleedingrisk.
ForpatientsbeingtreatedwithvitaminKantagonists(VKA)suchaswarfarin:
Lowbleedingriskprocedurespermitcontinuationoforalanticoagulationthroughtheperioperative
period (e.g., minor dental and dermatologic procedures, cataract extraction, endoscopy without
biopsy,arthrocentesis).Pacemakerandimplantablecardioverterdefibrillator(ICD)placementlead
tolesshematomaifanticoagulationisnotinterrupted.
31
Significantbleedingriskproceduresrequiretheanticoagulationtobediscontinued.
Although theinternational normalizedratio (INR) at which surgerycanbe safelyperformed is
subjective,anINRof<1.5istypicallyareasonablegoal.
TheVKAwilltypicallyneedtobestopped5dayspreoperatively.
TheINRshouldbecheckedthedaybeforesurgery.Ifalevel<1.5isnotobtained,1–2.5mgoral
vitaminKeffectivelyachievesanINR<1.5onthedayofsurgery.
The VKA cangenerally be resumed 12–24 hours postoperativelyif postoperative bleeding has
beencontrolled.
32
High bleeding risk procedures (e.g., intracranial or spinal) with potential catastrophic outcomes
because of bleeding will preclude any anticoagulation in the perioperative period. Resumption of
anticoagulationshouldbedelayedatleast48hoursforotherprocedureswithhighbleedingrisk(e.g.,
sessilepolypectomy,bowelresection;kidney,liver,orspleenbiopsy;extensiveorthopedicorplastic
surgery).
BridgingtherapyreferstotheadministrationofanalternativeanticoagulationduringthetimetheINR
isanticipatedtobebelowthetherapeuticrange.Thepotentialdecreaseinthrombosismustbeweighed
againsttheincreasedriskofbleeding.
33
Highthromboticriskpatientswiththefollowingconditionsshouldtypicallybetreatedwithbridging
therapy:
Mechanicalmitralvalve
Older-generationmechanicalvalve(e.g.,Starr-Edwardsball-in-cagevalve)
Anymechanicalvalvewithahistoryofcardioembolismwithinthepreceding6months
NonvalvularAFwitheitherahistoryofembolisminthelast3monthsorCHADS2score≥5
ValvularAF
RecentVTE(<3months)
Knownthrombophilicstate(e.g.,proteinCdeficiency)
Formoderate thromboticriskpatients as below,bridging may be considered inpatientswithlow
bleedingrisk.DVTprophylaxisdosingisacceptable.
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Mechanicalaorticvalve(bileaflet)withoneormoreassociatedriskfactors:AF,CHF,hypertension,
age≥75years,diabetesmellitus,andpriorCVAorTIA
HistoryofVTEwithinpreceding3–12months
Non–high-riskthrombophilia(e.g.,heterozygousfactorVLeidenmutation)
HistoryofrecurrentVTE
Activemalignancy
Low thrombotic risk patients are not believed to require bridging therapy. Treatment with DVT
prophylaxisdosesofLMWHorUFHisanalternative.Thisgroupincludespatientswith:
Mechanicalaorticvalve(bileaflet)withoutassociatedriskfactors,asabove
AFwithaCHADS2score<4,orhistoryofpriorembolism
34
PriorVTE>12monthsprior(withouthistoryofrecurrentVTEorknownhypercoagulablestate)
ChoicesforbridgingtherapyaregenerallytheLMWHsandUFH,includingpatientswithmechanical
heartvalves.31Thereislessexperienceinthissettingwithotheragents(e.g.,fondaparinux),andtheir
usecannotbeconsideredroutine.
LMWHs have the advantages of relatively predictable pharmacokinetics and ability to be
administered SC. Monitoring of anticoagulant effect is typically not required. Renal dosing is
available forpatientsnotondialysis. Subcutaneous administrationallows foroutpatienttherapyin
appropriatepatients.Thisdecreasesthe lengthandcostofhospitalization. Thelastdoseshouldbe
given24hourspriortosurgery.
UFH is the agent of choice for patients with end-stage renal disease (ESRD). It is typically
administeredIVandrequiresfrequentmonitoringoftheactivatedpartialthromboplastintime.UFH
shouldbestoppedatleast4hourspriortotheplannedsurgicalproceduretoallowtheanticoagulant
effecttowane.Fixed-dosesubcutaneousUFHhasbeenprovenefficaciousfortreatmentofVTEand
maybeconsideredasanoption.
35
Directoralanticoagulantshaverelativelyshorthalf-lives(dabigatran=14hours,rivaroxaban=9
hours,apixaban=12hours),obviatingtheneedforbridginganticoagulation.Agentsshouldbeheld
fortwoorthreehalf-livesforlowbleedriskproceduresandthreeorfourhalf-livesforhighbleed
riskprocedures,keepinginmindtheeffectsofrenalfunctiononclearance.
Reversalagentsmaybeusedifurgentsurgeryisrequiredbeforethiswashoutperiod.
Idarucizumabreversesdabigatran,andandexanetalfareversesallXainhibitors.
Patientsbeingtreatedwithantiplateletagents
Continuing antiplatelet therapyperioperatively carries a riskof bleeding, whereas discontinuation
mayincreasecardiovascularevents.Irreversibleagentsmustbewithheldfor5–7daysbeforeeffects
fullyabate.Cliniciansareagainleftwithlittleevidenceandsometimesconflictingguidelines.
Lowbleedingriskprocedures(e.g.,minordermatologicordentalprocedures) allowcontinuation
of aspirin (acetylsalicylic acid [ASA]) being given for secondary prevention of cardiovascular
disease.
Noncardiacsurgerypatients should generallyhaveclopidogrel (or other thienopyridines)held 5
days preoperatively. Prompt reinitiation with a loading dose of 300 mg should take place
postoperatively.FurtherstratificationdrivesdecisionsregardingASA:
Moderatetohighcardiacrisk,inwhichcaseASAshouldbecontinuedperioperatively
Lowcardiacrisk,inwhichcaseASAshouldbeheld7dayspreoperatively
CoronaryarterybypassgraftcandidatesshouldgenerallycontinueASAperioperativelyandhave
clopidogrelheld5dayspreoperatively.
Coronary stents pose a particular risk of in-stent thrombosis and infarction if dual antiplatelet
therapyisprematurelywithheld.Wheneverpossible,surgeryshouldbedeferreduntiltheminimum
period ofdualantiplatelet therapyis completed(balloonangioplasty withoutstent,14 days;drug-
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elutingstents,6months;baremetalstents,30days).
Urgentsurgerieswithinthe previoustimeframes shouldproceedwith continueddualantiplatelet
treatment,ifpossible.Ifthebleedingriskisfelttobehigh,ASAaloneshouldbecontinued.Heparin
bridginghasnotbeenshowntobeofbenefit.Bridging withIV glycoproteinIIb/IIIaantagonistsor
reversibleoralagents(e.g.,ticagrelor)isnotroutinelyrecommended.
36
PerioperativeManagementofSpecificConditions
Hypertension
GENERALPRINCIPLES
Antihypertensiveagentsthatthepatienthastakenpriortoadmissionforsurgerymayhaveanimpacton
theperioperativeperiod.
Whenthepatientisreceivingβ-blockersorclonidinechronically,withdrawalofthesemedications
mayresultintachycardiaandreboundhypertension,respectively.
Evidencesuggeststhatholdingangiotensin-convertingenzymeinhibitorsandangiotensinIIreceptor
blockersonthedayofsurgerymayreduceperioperativehypotension.37Theseagentsshouldnotbe
heldifgivenforHFrEF.
TREATMENT
Hypertensioninthepostoperativeperiodisacommonproblemwithmultiplepossiblecauses.
Allreversiblecausesofhypertension,suchaspain,agitation,hypercarbia,hypoxia,hypervolemia,
andbladderdistention,shouldbeexcludedortreated.
Poor control of hypertension secondary to discontinuing medications the patient was previously
taking intheimmediate postoperative period is notuncommon;thus, reviewingthepatient’shome
medicationlistisrecommended.
Many parenteral antihypertensive medications are available for patients who are unable to take
medicationsorally.Transdermalclonidinealsoisanoption,buttheonsetofactionisdelayed.
PacemakersandICDs
GENERALPRINCIPLES
Theuseofelectrocauteryintraoperativelycanhaveadverseeffectsonthefunctionofimplantedcardiac
devices.
Avarietyoferrorscanoccur,fromresettingthedevicetoinadvertentdischargeofanICD.
Complicationsarerarebutaremorelikelywithabdominalandthoracicsurgeries.
Thetypeofdevice(i.e.,pacemakerorICD)andmanufacturershouldbedeterminedalongwithinitial
indicationforplacementandthepatient’sunderlyingrhythm.HistoryandECGreviewshouldsuffice.
Thedeviceshouldbeinterrogatedwithin3–6monthsofasignificantsurgicalprocedure.
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TREATMENT
Ifthe patientispacemakerdependent,the device shouldbereprogrammedtoanasynchronous
mode(e.g.,VOO,DOO)forthesurgery.
Theapplicationof a magnetwill cause mostpacemakers torevert toanasynchronouspacingmode;
however, if this is the planned management, it should be tested preoperatively, especially in the
pacemaker-dependentpatient.
It should be noted that the effect of a magnet on ICDs is typically different from the effect on
pacemakersinthatitaffectstheantitachycardiafunctionbutdoesnotalterthepacingfunctionofmost
models.IfthepacingfunctionofanICDneedstobealteredperioperatively,thedevicewillneedtobe
reprogrammed.
The antitachycardia function of an ICD will typically need to be programmed off for surgical
procedures in which electrocautery may cause interference with device function, leading to the
potential for unintentional discharge. The effect of a magnet on this function is variable, so
programmingisthepreferredmanagement.Continuousmonitoringforarrhythmiaisessentialduringthe
periodwhenthisfunctionissuspended.
Postoperative interrogation may be necessary, particularly if the device settings were changed
perioperativelyorifthepatientispacemakerdependent.
Consultation with an electrophysiologist is strongly recommended if there is any uncertainty
regardingtheperioperativemanagementofadevice.
PulmonaryDiseaseandPreoperativePulmonaryEvaluation
GENERALPRINCIPLES
Clinicallysignificantpulmonarycomplicationsincludeatelectasis,pneumonia,bronchospasm,
exacerbationofpreexistingchroniclungdisease,andrespiratoryfailure.38Postoperativerespiratory
failure,definedasventilatordependencyformorethan48hoursorunplannedreintubation,carriesa30daymortalityrateashighas26.5%.
39
RiskFactors
Surgicalsiteisgenerallyconsideredthegreatestdeterminantofriskofpulmonarycomplications,with
proximitytothediaphragmcorrelatingwithincreasingrisk.40Neurosurgeryandsurgeriesinvolvingthe
mouthandpalatealsoimpartincreasedrisk.
39,41
Durationofsurgeryalsocorrelatesstronglywithrisk.
42-44
Regionalanesthesia mayreduceriskofpneumoniaandrespiratoryfailure as comparedwithgeneral
anesthesia.
45-47
Prolonged neuromuscular blockade is also strongly associated with postoperative
pulmonarycomplications.
48
COPD is a well-known risk factor, with disease severity associated with risk of serious
complications.
49
Interstitial lung disease places patients at elevated risk for surgical lung biopsy and resection of
malignancybutisnotaswellstudiedinpatientsundergoinggeneralsurgery.
50-52
Pulmonaryhypertensionisassociatedwithsignificantmorbidityinpatientsundergoingsurgery.
53,54
Conversely, treated asthma and restrictive physiology associated with obesity do not appear to be
significantriskfactors.
55,56
CHFmayincrease theriskofpulmonarycomplicationstoanevengreaterdegreethanthatseenwith
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COPD.
57
Multiple indices ofgeneral healthstatusincludingdegree of functional dependence andAmerican
Society of Anesthesiologists (ASA) class have beenlinked topoor pulmonary outcomes.
56,57
Odds
ratiosforpostoperativerespiratoryfailureof2.53and2.29wereobservedforhypoalbuminemia(<3
g/dL)andazotemia(BUN>30mg/dL),respectively,inalargecohort.
41
Age >50 years has been identified as an independent predictor of postoperative pulmonary
complications.Riskincreaseslinearlywithage.
Smoking is a well-established risk factor for both postoperative pulmonary and nonpulmonary
complications. As with malignancy, risk appears to be dose-dependent and associated with active
use.
44,58,59
Obstructivesleepapnea(OSA)increasestheoddsofpostoperativecomplicationstwo-tofourfold.
60
UnrecognizedOSAmayposeanevengreaterrisk;itisestimatedthatover50%ofpatientswithOSA
presentingforsurgeryareundiagnosed.
61-63
RiskStratification
Severalvalidatedriskindices havebeendeveloped for quantitating riskofpostoperative pulmonary
complications.Ofthese,theArozullahrespiratoryfailureindexoffersbothpracticalityandeaseofuse.
Itconsistsofsixfactorsforwhichpointscoresareassignedbasedonmultivariateanalysistostratify
patientsintofiveclassesofpostoperativerespiratoryfailurerisk(rangingfrom0.5%to26.6%).
41
DIAGNOSIS
ClinicalPresentation
HISTORY
Preoperativepulmonaryevaluationshouldfocusontheabovementionedpatient-dependentriskfactors.
Is there a history of lung disease? If so, what is the patient’s baseline (e.g., level of exertional
tolerance, degree of hypoxemia)? Is there evidence of recent deterioration (e.g., increased cough,
sputumproduction)?Thoughnotanabsolutecontraindicationtosurgery,itmaybeprudenttopostpone
an elective procedure until an exacerbation is treated or a superimposed upper respiratory tract
infectionhasresolved.
Afullsmokinghistoryshouldbeobtained.
ScreeningforOSAshouldbeundertaken.TheSTOP-Bangquestionnaire(seeChapter10,Obstructive
SleepApnea)canbeimplementedtodetermineriskofOSA.
Asnonpulmonarycomorbiditiesimpactthelikelihoodofpulmonarycomplications,areviewofother
organsystemsismandatory.
PHYSICALEXAMINATION
Vital signs canbe helpful indetermining pulmonary risk.Bothbody mass index (BMI)andBP are
componentsoftheSTOP-Bangquestionnaire.Oxygensaturationbypulseoximetrymayassistinrisk
stratification.
64
HighMallampati score may corroborate clinical suspicion for OSA. A study of 137 adults being
evaluatedforOSAfoundthatevery1-pointincreaseinMallampatiscoreincreasedtheoddsofOSAby
2.5.
65
Stigmata of chronic lung disease (e.g., increased anteroposterior dimension of the thorax, digital
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clubbing,adventitiouslungsounds)shouldbeactivelysoughtalongwithsignsofdecompensatedHF
(jugularvenousdistention,rales,pretibialedema).
DiagnosticTesting
Routinelaboratorytesting
As mentioned earlier, underlying chronic kidney disease and hypoalbuminemia portend increased
riskofpostoperativepulmonary complications.Theadditionofserumbicarbonate28 mmol/Lor
abovetoaSTOP-Bangscoreofthreeor above increasesthe specificityfordetectingmoderateto
severeOSAfrom30%to82%,thoughsensitivityisaccordinglyreduced.
66
CXR
As many findings deemed abnormal on routine CXR are chronic and do not alter management,
imaging is recommended only if signs or symptoms (e.g., unexplained dyspnea) warrant
investigation.
67,68
Arterialbloodgas(ABG)analysis
No data exist that suggest that ABG results contribute to risk estimation beyond the variables
delineatedearlier.
Pulmonaryfunctiontesting(PFTs)
ThevalueofpreoperativePFTsisatbestdebatableoutsideoflungresectionsurgery,whereitsrole
is relatively well defined. However, they may be considered in further evaluation of selected
patients with unexplaineddyspnea or exertional impairmentor for thosewith known lungdisease
withunclearbaseline.
TREATMENT
Preoperativetreatmentshouldfocusonmodifiableriskfactors.
Theeffectofpreoperativesmokingcessationonpulmonarycomplicationshasbeenlargelydescribed
incardiothoracicsurgeries,whereabenefittoquittingsmokingatleast2monthspriortosurgery
hasbeenshown.69Thoughtheeffectonageneralsurgicalpopulationislessclear,pooleddatashowa
significant reduction in pulmonary complications.70 Maximizing the preoperative smoking cessation
period appears to minimize complications. Though it is unknown whether smoking cessation is
beneficialwithin2weeksofsurgery,previousconcernsaboutaparadoxicalincreaseincomplications
appearunfounded.
71
COPD and asthma therapy should be optimized (see Chapter 9, Obstructive Lung Disease), and
respiratorytractinfectionsshouldbetreated.Indeed,riskofpostoperativepulmonarycomplicationsis
increased in the month following a respiratory tract infection.72 Nonemergent surgery may need
postponementtoallowrecoveryofpulmonaryfunctiontobaseline.
OSA should be treated prior toelective high-risk surgerywhen feasible. A cohortstudy revealed a
significant reduction in cardiovascular complications (primarily cardiac arrest and shock) between
undiagnosedanddiagnosedOSAafterprescriptionofcontinuouspositive airwaypressure (CPAP).
73
However, a subsequent meta-analysis of 904 patients failed to show a significant difference in
postoperativeadverseeventsdespitestatisticallysignificantreduction inapnea–hypopneaindexwith
postoperativeuseofCPAP,afindingattributedtooverallpooradherence.74PatientswithknownOSA
shouldbecontinuedonCPAPperioperatively.
75
Alternative procedures with reduced pulmonary risk should be considered for high-risk patients.
Laparoscopicproceduresmayyieldfewerpulmonarycomplications;regionalnerveblockappearsto
beassociatedwith decreased riskaswell.
76,77
If generalanesthesia(particularlywith neuromuscular
blockade)isabsolutelynecessary,durationshouldbeminimizedtothedegreepossible.
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AnemiaandTransfusionIssuesinSurgery
GENERALPRINCIPLES
Thereisnostandardizedpreoperativeevaluationforanemia.
Forlow-riskprocedures,thereisnoevidencethatroutinetestingofasymptomaticindividualsbefore
low-riskproceduresincreasessafety.
78
For higher risk procedures, particularly those with higher bleeding risk, a baseline CBC and
coagulationprofilearetypicallyobtained.Furthertestingshouldbeperformedasindicated.
DIAGNOSIS
Ahistoryofanemia,hematologicdisease,orbleedingdiathesisshouldbenotedonhistoryorreviewof
medicalrecords.
Any clinical signs of anemia (e.g., pallor) or coagulopathy (e.g., petechiae) should prompt further
evaluation.
TREATMENT
Volumeresuscitationandcontrolofactivebleedingaretheinitialtherapyofanemia,particularlyinthe
perioperativeperiodwhenacutebloodlossisacommonoccurrence.
A restrictive red blood cell (RBC) transfusion threshold of 8 g/dL is recommended for patients
undergoingorthopedicsurgeryandcardiacsurgeryandthosewithpreexistingcardiovasculardisease.
79
Inmostothercircumstances,atransfusionthresholdof7g/dLsuffices.
SPECIALCONSIDERATIONS
Patientswithsicklecellanemiashouldgenerallybetransfusedtoahemoglobinlevelof10g/dL
preoperativelytodecreasetheincidenceofcomplications.
80
LiverDisease
GENERALPRINCIPLES
Patientswithliverdiseasefaceincreasedoperativemorbidityandmortalityincomparisontothosewith
normalhepaticfunction.Notonlydoesthestressofsurgeryplacethematriskforacutehepatic
decompensation,themyriadsystemiceffectsofliverdiseaseresultinanincreasedfrequencyof
complicationstomultipleotherorgansaswell.
Classification
Both the older Child–Turcotte–Pugh (CTP) and more recent Model for End-stage Liver Disease
(MELD)classificationschemes(seeChapter19,LiverDiseases)arewell-validatedstatisticalmodels
forpredictingsurgicalriskinpatientswithcirrhosis.
Two differentstudies separatedby13yearsrevealed strikinglysimilar results: amortalityrateof
10% for patients with CTP class A, 30% for class B, and 76%–82% for class C cirrhosis.
81,82
Accordingly, it has been suggested that patients with CTP class A cirrhosis can safely undergo
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elective surgery ingeneral,andthosewithclass Ccirrhosisshouldnotunderany circumstances.
83
However,thedistinctionislessclearforclassBcirrhosis,andtheinherentsubjectivityoftheCTP
systemlimitsitsdiscriminatoryability.
84
MELDoffersseveraladvantagesforcalculationof30-daymortality:
Variablesarebothobjectiveandweighted.
Itincludesserumcreatinine,whichhasbeenshowntocorrelatewithpostoperativemortality.
85
PredictiveperformanceisequaltoifnotbetterthanthatofCTP.
86-88
Because CTP includes ascites, which is also correlated with poor prognosis in general surgical
patients, the two scoring systems could be considered complementary rather than mutually
exclusive.
89,90
American Society of Anesthesiologists (ASA) class appears to be the strongest predictor of 7-day
mortality in cirrhotic patients undergoing surgery.91 All 10 patients with ASA class V disease died,
indicatingthatASAclassVshouldbeacontraindicationtosurgeryotherthanlivertransplantation.
92
DIAGNOSIS
ClinicalPresentation
Significanthepaticdiseasethatgreatlyimpactssurgicalrisk(e.g.,acuteliverfailure,advancedcirrhosis)
isusuallyclinicallyobvious(scleralicterus,abdominaldistentionfromascites,floridencephalopathy).
Formilderdisease,however,moresubtlefindingssuchasspiderangiomas,palmarerythema,and
testicularatrophymaybetheonlyclues.Historicaldetailssuchasfamilyhistoryofhepaticdisease,
currentorprioralcoholand/orIVdrugabuse,andtransfusionhistorymayincreaseclinicalsuspicion.See
Chapter19,LiverDiseases,forfurtherdetails.
DiagnosticTesting
Becauseoftheexceedinglylowyieldoflaboratorytesting(0.14%inoneprospectivestudyenrolling
7620patients),routinepreoperativeassessmentofhepaticfunctionisnotrecommendedunlessclinical
findingsdictate.
83,93
Those with suspected or known hepatic disease should undergo thorough laboratory evaluation
including hepatic enzyme levels, albumin and bilirubin measurement, and coagulation studies along
with renal function and electrolytes. If significant laboratory abnormalities (e.g., unexplained
transaminaseelevation>threetimesupperlimitofnormal)arefoundinpatientswithoutknownliver
disease,surgical interventionmayneedtobe postponedtoallow furtherworkup,astheincidenceof
undiagnosedcirrhosisinthispopulationmaybe6%orevenhigher.
83,94
TREATMENT
Historically, patients with acute viral or alcoholic hepatitis have been observed to tolerate surgery
poorlyanddelayingsurgeryuntilclinicalandbiochemicalrecoveryisrecommended.
83,95,96
Patientswithmildchronichepatitiswithoutassociatedcirrhosisgenerallytoleratesurgerywell.
97
Forpatientswithcirrhosis,severalstepsshouldbetakentooptimizepreoperativestatus:
Coagulopathyshouldbetreatedtominimizeriskofhemorrhage.VitaminKsupplementationmaybe
helpful if the INR is elevated. However, in the context of marked hepatic synthetic dysfunction,
administration of fresh frozen plasma and/or cryoprecipitate may be necessary. Severe
thrombocytopenia should be corrected via transfusion.(See Chapter20, Disorders of Hemostasis
andThrombosis,underLiverDisease.)
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Ascirrhosisisassociatedwithrenaldysfunction,intravascularhypovolemia,andextravascularfluid
retention, careful attention to volume status is crucial. Nephrotoxic agents should be used with
extremecautionifatall,andfreewaterrestrictionmayberequiredinpatientswithserumsodium
below130mEq/L.However,judicioususeofdiureticsand/ortimelyparacentesismayberequired
tocontrolascites,particularlyifabdominal surgery is being considered.98 Administrationof large
amounts of crystalloid should be avoided. Despite theoretical benefits, strong evidence for
preoperative transjugular intrahepatic portosystemic shunt to reduce portal hypertension prior to
majorabdominalsurgeryremainslackingbutmaybeconsideredinselectcircumstances.
90
Closeattentiontonutritionalstatusiswarrantedinlightoftheveryhighincidenceofmalnutritionin
thispopulation.
99
Lastly,encephalopathyfrequentlycomplicatessurgicalintervention.
100
Lactuloseshouldbetitratedto
three to four bowel movements per day, and concurrent rifaximin therapy should be strongly
considered.
101
Opioiduseshouldbe minimizedtoavoidconstipationandileus,anddosereduction
shouldbeconsideredinlightofexpectedreducedhepaticclearance.
DiabetesMellitus
GENERALPRINCIPLES
Medicalandsurgicalpatientswithhyperglycemiaareatincreasedriskforpooroutcomes.
102
Thefactthathyperglycemia is a marker for poor outcomes appears tobe relativelyclear.However,
whetheraggressivemanagementtrulyimprovesoutcomesisuncertain.Trialresultshavebeenmixed.
TREATMENT
Elective surgeryinpatientswith uncontrolleddiabetesmellitusshould preferablybe scheduledafter
acceptableglycemiccontrolhasbeenachieved.Ifpossible,theoperationshouldbescheduledforearly
morningtominimizeprolongedfasting.Frequentmonitoringofbloodglucoselevelsisrequiredinall
situations.
Type1diabetes
Someformofbasalinsulinisrequiredtopreventketosis.
Ontheeveningpriortosurgery,theregularlyscheduledbasalinsulinshouldbecontinued.Iftakenin
the morning, it is still recommended to give the regularly scheduled basal insulin without dose
adjustment.
103
However, patients who are tightly controlled may be at increased risk for
hypoglycemia and will need to be monitored closely. A decrease in the last preoperative basal
insulindosemaybeconsideredinthiscircumstance.
Glucoseinfusions(e.g.,D5-containingfluids)canbeadministeredtoavoidhypoglycemiawhilethe
patientisNPOanduntiltoleranceoforalintakepostoperativelyisestablished.
For complex procedures and procedures requiring a prolonged NPO status, a continuous insulin
infusionwilllikelybenecessary.
Cautionshouldbeexercisedwiththeuseofsubcutaneousinsulinintheintraoperativeandcritical
caresettings,asalterationsintissueperfusionmayresultinvariableabsorption.
Type2diabetes
Treatmentoftype2diabeticsvariesaccordingtotheirpreoperativerequirementsandthecomplexity
oftheplannedprocedure.
104
Diet-controlledtype2diabetescangenerallybemanagedwithoutinsulintherapy.Glucosevalues
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should be checked regularly(four timesdailyat minimum). Elevatedlevels (>180mg/dL)can be
treatedwithintermittentdosesofshort-actinginsulin.
Type2diabetesmanagedwithoraltherapy
Short-actingsulfonylureasandotheroralagentsshouldbewithheldontheoperativeday.
Metforminshouldbewithheld1daybeforeplannedsurgicalprocedures.Metforminisgenerally
heldfor48hourspostoperativelyprovidedthereisnoacuterenalinjury.Otheroralagentscanbe
resumedwhenpatientsaretoleratingtheirpreprocedurediet.
Glucosevaluesshouldbecheckedregularlyandelevatedlevels(>180mg/dL)canbetreatedwith
intermittentdosesofshort-actinginsulin.
Type2diabetesmanagedwithinsulin
Long-acting insulin (e.g., glargine insulin) can be given at 50% of the usual dose the day of
surgery.
Intermediate-actinginsulin(e.g.,Neutral ProtamineHagedorn) can be givenatone-halftotwothirdsoftheusualmorningdose.
Dextrose-containingIVfluidsmayberequiredtoavoidhypoglycemia.
Theusualinsulintreatmentcanbereintroducedonceoralintakeisestablishedpostoperatively.
Targetglucoselevels
There are no generally agreed-upon target glucose levels applicable to the entire postsurgical
population. Pending further research, a goal of maintaining glucose levels <180 mg/dL in the
postoperative setting seems reasonable. It should be noted that this may still require intensive
treatmentssuchasinsulininfusion.
In patients treated with sliding scale insulin, it is essential to monitor the response to therapy.
Patients who are hyperglycemic consistently are unlikely to have adequate glucose control with
intermittent treatment alone, and a basal/bolus regimen should be introduced if hyperglycemia is
persistent.
105
AdrenalInsufficiencyandCorticosteroidManagement
GENERALPRINCIPLES
Surgeryisapotentactivatorofthehypothalamic–pituitaryaxis,andpatientswithadrenalinsufficiency
maylacktheabilitytorespondappropriatelytosurgicalstress.
Patients receiving corticosteroids as anti-inflammatory therapy may rarely develop postoperative
adrenalinsufficiency.
Thedoseandduration ofexogenouscorticosteroidsrequiredtoproduceclinicallysignificanttertiary
adrenalinsufficiencyishighlyvariable,butgeneralprinciplescanbeoutlined.
104
Daily therapy with 5 mg or less of prednisone (or its equivalent), alternate-day corticosteroid
therapy, and any dose given for <3 weeks should not result in clinically significant adrenal
suppression.
Patientsreceiving>20mg/dprednisone(orequivalent)for>3weeksandpatientswhoareclinically
“cushingoid” in appearance can be expected to have significant suppression of adrenal
responsiveness.
The function of the hypothalamic–pituitary axis cannot be readily predicted in patients receiving
dosesofprednisone5–20mgfor>3weeks.
DIAGNOSIS
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