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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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Ketamine Sedation,
amnesia,
analgesia
1–3mg/kg 30 5–10 IncreasesHRandBP;
bronchodilator;may
elevateICP
Succinylcholine Paralytic 1–1.5mg/kg 30–60 5–15 Contraindicatedin
hyperkalemia,historyof
malignanthypothermia,
myopathy
Rocuronium Paralytic 1mg/kg 45–60 30–45 Cautionifdifficult
intubationorbag-valvemaskventilation
anticipated
BP,bloodpressure;HR,heartrate;ICP,intracranialpressure.
Ifpatientnotinextremis/cardiacarrest,averbaltime-outshouldbeperformed.
Techniques
Direct laryngoscopic orotracheal intubation: Most commonly used, requiring only a direct
laryngoscopeandlightsource.ProcedureavailableinTable8-3.
TABLE8-3
PROCEDURE FOR ENDOTRACHEAL INTUBATION, NEEDLE CRICOTHYROTOMY,
ANDCRICOTHYROTOMY
EndotrachealIntubationUsingDirectLaryngoscopy
Equipment Oxygentubing,bag-valve-maskdevice,suctionandtubing,oralairway,
laryngoscope,laryngoscopeblades,endotrachealtubewithstylet,syringe,
end-tidalcarbondioxidecolorimeter
Technique Step1Placethepatientinthe“sniffing”position,withneckflexedandhead
extended;obesepatientswillrequireshoulderrollorramp.
Step2Preoxygenatethepatientwith100%oxygenthroughthebag-valve-
maskdeviceuntilsaturationsaremaintainedat>95%for3–5minand
suctionoralsecretionsasnecessary.
Step3Duringpreoxygenation,ensurethatallequipmentnecessaryispresent
andfunctional:checktheendotrachealtubecuffwithinflationand
deflationandthatthelightofthelaryngoscopeisfunctional.
Step4Administerintravenous(IV)sedation;oncethepatientisappropriately
sedated,openthemouthwiththerighthandandinsertthe
laryngoscopebladeintotherightsideofmouthwiththelefthand,
sweepingthetonguetotheleft.
Step5Advancethebladetothebaseofthetongueandthenliftverticallyto
visualizethevocalcords;donottiltthelaryngoscope.
Step Ifvocalcordsarevisible,inserttheendotrachealtubewiththestylet
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6 withtherighthand;oncethecuffispastthevocalcords,removestylet.
Donotattemptintubationifthevocalcordsarenotvisible.
Step7Advancetheendotrachealtubeuntilitisat21cmatthegum/teethfor
womenand22cmformenandinflatethecuff.
Step8Checktubelocationwithend-tidalcarbondioxidecolorimeter,
auscultationoverthechestandabdomen,ANDchestradiograph.
NeedleCricothyrotomy
Equipment Large-boreIVcatheterwithneedlestylet,3-mLLuerlocksyringewith
plungerremoved,7-mminnerdiameterendotrachealtubeadapter
Technique Step1Extendtheneckandidentifythecricothyroidmembrane,locatedinferior
tothethyroidcartilageandsuperiortothethyroidgland.
Step2Stabilizethethyroidcartilagewiththenondominanthandand,usingthe
dominanthand,introducetheIVcatheterwiththeneedlestyletata45degreeanglethroughthecricothyroidmembraneintothetrachea,
aspiratingairtoconfirmlocation.
Step3Advancethecathetertothehub,andremovetheneedlestylet.
Step4AttachtheLuerlocksyringetothecatheterandthentheendotracheal
tubeadaptertothesyringetoallowforbag-valveventilation.
Cricothyrotomy
Equipment Scalpel,Kellyforceps,6-mminnerdiameterorsmallerendotrachealtube
Technique Step1Extendtheneckandidentifythecricothyroidmembrane,locatedinferior
tothethyroidcartilageandsuperiortothethyroidgland.
Step2Stabilizethethyroidcartilagewiththenondominanthandand,usingthe
dominanthand,makea1-cmhorizontalincisionjustabovethesuperior
borderofthecricoid.
Step3UsingtheKellyforceps,dissectuntilthecricothyroidmembraneis
visualizedandthenmakeaverticalincisionthroughthemidlineofthe
membrane,beingcarefultonotpassthebladetoodeeply.
Step4WidentheincisionwithKellyforcepsuntiltheendotrachealtubecanbe
insertedandtheninflatethecuff.
Videolaryngoscopicorotrachealintubation:Allowsfordirectvisualconfirmationofintubationbya
secondobserverviavideomonitoringandisparticularlybeneficialinmoredifficultairways.
Advanced techniques for specialists include blind nasotracheal intubation and flexible fiber
opticallyguidedorotrachealornasotrachealintubation.
Verification of correct endotracheal tube location and positioning: Proper tube location must be
ensuredby:
Fiberopticinspectionoftheairwaysthroughtheendotrachealtube;or
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Directvisualizationoftheendotrachealtubepassingthroughthevocalcords;and
Useofanend-tidalCO2monitor;and
CXR.
Clinical evaluation ofthe patient (i.e., listeningfor bilateral breathsounds over the chestand the
absence of ventilation over the stomach) and radiographic evaluation alone are unreliable for
establishingcorrectendotrachealtubelocation.
Thetipoftheendotracheal tubeshould be 3–5 cm abovethecarina,depending onheadandneck
position.
Aftersuccessfulintubation:
Tracheal tube cuff pressures: Should be monitored at regular intervals and maintained below
capillaryfillingpressure(25mmHg)topreventischemicmucosalinjury.
Sedation: Anxiolytics and opiates are frequently used to facilitate endotracheal intubation and
mechanicalventilation.CommonlyusedagentsarelistedinTable8-4.
TABLE8-4
COMMONLYUSEDSEDATIONMEDICATIONSINTHEINTENSIVECAREUNIT
Drug Dose(IV) Timeto
Arousal
Comment
Propofol 20–
100µg/kg/min
10–
15min
Causeshypotension,maycause
hypertriglyceridemiaorpropofol-related
infusionsyndrome,beneficialin
bronchospasm
Midazolam 1–10mg/h 1–2h Arousaltimecanbeprolonged;active
metaboliteaccumulatesinrenalfailure;
associatedwithdelirium
Fentanyl 25–200µg/h 15s Cancausechestwallrigidityandserotonin
syndromeathigherdoses
Ketamine 0.5–
3mg/kg/h
5–
10min
Maycausehypertensionandtachycardia;
mayexperiencereemergencehallucinations,
beneficialinbronchospasm.
Dexmedetomidine 0.1–
1.5mg/kg/h
6–
10min
Doesnotcauserespiratorydepression,can
causehypotensionandbradycardia
Complications: Improper endotracheal tube location or positioning is the mostimportant immediate
complicationtoberecognizedandcorrected.
Esophagealintubationshouldbesuspectedifnoend-tidalCO2isdetectedafterthreetofivebreaths,
hypoxemia persists or develops, there is a lack of breath sounds, or abdominal distention or
regurgitationofstomachcontentsoccurs.
Mainstem intubation should be suspected if peak airway pressures are elevated or there are
unilateralbreathsounds.
Othercomplicationsincludedislodgmentofteethandupperairwaytrauma.
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SurgicalAirways
Indicationsforsurgicalairwaysincriticalcare
Life-threatening upper airway obstruction (e.g., epiglottitis, angioedema, facial burns,
laryngeal/vocalcordedema)preventingbag-valve-maskventilationandendotrachealintubation.
Needforprolongedrespiratorysupport.
Needle cricothyrotomy: Indicated in emergency settings when the patient cannot be ventilated
noninvasively, standard endotracheal intubation is unsuccessful, and a surgical airway cannot be
immediatelyperformed.ThestepsoftheprocedurearelistedinTable8-3.
Cricothyrotomy: Indicated in emergency settings when the patient cannot be ventilated
noninvasivelyandstandardendotrachealintubationis unsuccessful.Thestepsoftheprocedureare
listedinTable8-3.
Tracheostomy:Predominantlyperformedowingtoneedforprolongedrespiratorysupport.
Theoptimaltime toperformatracheostomyina patientrequiringprolongedrespiratorysupportis
somewhatcontroversial.A2010randomizedcontrolledtrial(RCT)didnotdemonstrateanybenefit
inregardtooccurrenceofventilator-associatedpneumonia(VAP)orlong-termoutcomesforthose
whoreceivedanearlytracheostomy(after6–8daysofintubation)comparedwithlatetracheostomy
(after 12–14 days of intubation).9 A 2013 multicenter RCT from the United Kingdom comparing
early(within4daysofintubation)vslate(after10days)tracheostomyfoundnodifferencein30-day
mortality, ICU length of stay (LOS), or hospital LOS between the two groups.10 Generally,
tracheostomy shouldbeconsideredifprolongedventilatorysupportisanticipatedafter10–14
daysofendotrachealintubation.
Complications:Tracheostomysitesrequireatleast72hourstomature,andtubedislodgmentbefore
maturationcanleadtoseriousandlife-threateningcomplications.
A tracheostomytubethathasbeendislodgedbeforestoma maturationshouldnotbereinserted
owingtotheriskofcreatingafalsetract.
Standard endotracheal intubation should be performed if a tracheostomy tube is dislodged
beforestomamaturation.
Tracheoinnominate artery fistulas are an uncommon but life-threatening complication of a
tracheostomy that occurs when an abnormal tract develops between the innominate artery and
trachea, leading to hemorrhage. This complication most commonly occurs 7–14 days after the
tracheostomybutcanoccurupto6 weeksafter theprocedure.Immediatemanagementincludes
overinflation of the tracheostomy tube cuff, digital compression of the stoma, and surgical
exploration.
11
MechanicalVentilation
GENERALPRINCIPLES
Basicmodesofventilation:Onecandeterminehowtheventilatorinitiatesabreath(triggering),howthe
breathisdelivered,howpatient-initiatedbreathsaresupported,andwhentoterminatethebreathtoallow
expiration(cycling).
Initiation of a breath: Triggering of a ventilator occurs after a period of time has elapsed (time
triggered) or when the patienthasgenerated sufficientnegative airwaypressureor inspiratoryflow
exceedingapredeterminedthreshold(patienttriggered).
Modesofventilation
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Assist-control(AC)ventilation:Ventilatordeliversafullysupportedbreathwhethertimeorpatient
triggered.Primarymodeofventilationusedinrespiratoryfailure.
Synchronizedintermittent mandatoryventilation(SIMV): Ventilator delivers a fully supported
breathwhentimetriggered.However,whenthebreathispatienttriggered,theventilatordeliversa
pressure-supportedbreath(at a level setbytheclinician).The sizeofthe patient-triggered breath
dependsonlungcomplianceandpatient’seffort.Thismodeiscommonlyusedinsurgicalpatients.
Pressure support ventilation (PSV): Spontaneous mode of ventilation without a set respiratory
rate. Delivers a clinician-determined inspiratory pressure during patient-triggered breathing. No
respiratoryrateisset,sothereisnoguaranteedminuteventilation.
Typeofbreathdelivered
Volumecontrol(VC):Ventilatordeliversaclinician-determinedtidalvolume(VT)foreachbreath
regardlessofwhetherthebreathwastimeorpatienttriggered.WhenpredeterminedVTisdelivered,
airflowisterminatedandexhalationoccurs.
Pressure control (PC): Delivers a practitioner-determined inspiratory pressure for each breath.
Wheninspiratory time has elapsed, inspiratory pressure is terminated and exhalation occurs. The
tidalvolumevariesbasedonlungcompliance.PCventilationdoesnotdeliveraguaranteedVTor
minuteventilationandmayleadtohypoventilation.However,PCmayimprovepatientsynchrony
andcomfortwhileontheventilator.
Basic ventilator terminology and management: Flow-time and pressure-time tracings are
demonstratedinFigure8-1.
Minuteventilation:DefinedastheproductofVTandrespiratoryrate(VT×RR).Normallybetween
5and10L/mininrestingadults,butmaybemuchhigherinhighmetabolicstates,e.g.,septicshock.
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Figure 8-1 Flow–time andpressure–time tracings.A, Pressure–time curve for one breath. B,Flow–time curve for
volume control ventilation.Pressure variesthroughoutinspiratorytime,dependingonlungcompliance.C,Pressure–time
curveforpressure controlventilation.Flowvaries throughoutinspiratorytime,dependingon lungcompliance. D,Flow–
timecurvedemonstratingauto–positiveend-expiratorypressure(auto-PEEP).
Peak airway pressure: Composed of pressures necessary to overcome inspiratory airflow
resistance,chestwall recoilresistance,andalveolar opening resistance.Doesnotreflectalveolar
pressure.
Mean airway pressure: Mean pressures applied during the inspiratory cycle. Approximates
alveolarpressureuntiloverdistentionoccurs.
Plateaupressure(P
plat
):Reflectsalveolarpressure.Checkedbyperforminganend-inspiratoryhold
maneuvertoallowpressuresthroughthetracheobronchialtreetoequilibrate.
VentilatorSettings
Initialventilatorsettings:Onemustdecideonaventilatormode(ACvs.SIMV),control(VCvs.PC),
respiratoryrate,FIO2,andPEEP.AC/VCisthemostcommonlyusedmode.
ForVC,thefollowingmustbeentered:
VT: Generally, begin at 6–8 mL/kg ideal body weight (IBW) to prevent barotrauma. There is
growingevidencethatlowtidalvolumeventilationmaybebeneficialinpatientswhetherornotthey
have acute ARDS and should be routinely used whenever possible.12 IBW can be calculated as
follows:MaleIBW=50kg+2.3kg/in.×(Heightininches−60)(imperial),50kg+1.1kg/cm×
(Height in cm − 152.4) (metric); Female IBW = 45.5 kg+ 2.3 kg/in. × (Height in inches − 60)
(imperial),45.5kg+1.1kg/cm×(Heightincm−152.4)(metric).
Inspiratory flow rate: May be constant (square wave) or ramp (decelerating). Recommend 60
L/minorgreater.Higherflowratesincreaseexpirationtime,whichmaybeimportantinobstructive
lungdiseasetopreventauto-PEEP (ventilatordeliversabreathbefore thepatienthasbeenable to
fullyexpire).
FIO2: Itis reasonable to start at100%, butFIO2 should be weaneddownquicklyto maintain SaO
2
>87%or PaO2>55mmHg.Thereis growing evidencethattolerating hyperoxiaafterintubationmay
actuallyworsenpatientsurvival.13FIO2cangenerallybequicklytitrateddownbasedonpulseoximetry
alone.
PEEP: Itis generallyreasonabletostartat5–10; however,higher valuesare frequently usedinthe
treatmentofARDS.
ARDSNetpublishesrecommendedstrategiesforPEEPandFIO2levels,whichareavailableontheir
website(http://www.ardsnet.org).
MorbidlyobesepatientsmayalsorequirehigherPEEP.
AdvancedModesofVentilation
Advancedmodesshouldgenerallyonlybeusedafterdiscussionwithhigherlevelpractitioners.
Pressure-regulatedVCventilation: Ventilatordetermines,after eachbreath,if inspiratorypressure
wassufficienttoachievetargetedVT;ifinsufficientorexcessive,thenventilatorwilladjustinspiratory
pressuretoachievedesiredVT.PRVCappliesaconstantpressurethroughoutinspiration,resultingina
deceleratingandvariableflowpatternthatismorecomfortableforsomepatients.
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Inverse-ratioventilation(IRV):Apressure-controlledmethodofventilationmostcommonlyusedin
ARDS.Inspiratorytimeexceedsexpiratorytimetoimproveoxygenationattheexpenseofventilation;
patientsare permittedto becomehypercapnic topH7.20. Ifobstructive lungdisease is present,can
causeauto-PEEPandexcessivehypercapnia.
Airwaypressurereleaseventilation(APRV):AnextremeversionofIRV;inspiratorypressure(P
high
)
applied for a prolongedperiod oftime (T
high
) witha short expiratorytime (T
low
, or release time)—
usually<1second—toallowforventilation.LikeIRV,patientsarepermittedtobehypercapnictopH
7.20.
High-frequencyoscillatoryventilation(HFOV):Apressurecontrolformofventilationthatdelivers
verysmall, rapid(as manyasseveralper second)breathssuperimposedonameanairwaypressure.
Thepressureissetatalevelthatwaspreviouslyrequiredtomaintainoxygenation,whereasthesmall
breaths facilitate CO2 clearance. HFOV was previously thought to improve outcomes in ARDS,
14
though subsequent prospective RCTs demonstrated no reduction15 and possibly an increase in
mortality.
16
MechanicalVentilationPrinciplesforPatientsWithARDS
OwingtoseverehypoxiaassociatedwithARDS,oxygenationandpreventionofbarotraumamayhaveto
beprioritizedoverventilation,resultinginhypercapnia.
Hypercapnia resulting in a pH of 7.20–7.35 often is tolerated to sufficiently oxygenate the patient
(“permissivehypercapnia”).
Theplateaupressureshouldbecheckedandthetidalvolumeshouldbedecreaseddownto4mL/kgof
IBWaspHallowstoachieveaplateaupressure≤30cmH2O.
Thereisgrowingevidencethatdrivingpressure(ratioofVT/respiratorysystemcompliance,orP
plat
−
PEEP)isanimportantpredictorofmortalityinpatientswithARDS.Whilethereisnostandardtarget
value,datasuggestthatdriving pressuresbelow14cmH2Oareassociatedwith betteroutcomes.
17,18
Practically, driving pressure can be used to identify patients with recruitable lung units who may
benefitfromhigherPEEPstrategies.
AdjunctstoMechanicalVentilation
Nitricoxide(NO):Improvesoxygenationbypreferentialvasodilationofcapillarybedsofventilated
lung.
NOmayhavesomebenefitinpatientswithpulmonaryhypertensionwhoareseverelyhypoxemic.
TheuseofNOinpatientswithoutpulmonaryhypertensionislimited.Studieshavesuggestedthatits
usagedoesnot improvemortalityinpatientswithARDSregardlessofthe degreeofhypoxia19and
increasestheriskforrenaldysfunction.
20
Inhaled prostacyclins: Similar to NO, theoretically, inhalation of prostacyclins—a class of
vasodilators—improves oxygenation by preferential vasodilation of the capillary beds ofventilated
lung.
Studieshaveshownthatinhaledprostaglandinsimproveoxygenationandpulmonaryarterypressure
inpatientswithARDS.21However,nostudieshavebeenperformedtoinvestigatewhethermortality
benefitexists.
Haveantiplateleteffects,sotheoreticalconcernforworseningdiffusealveolarhemorrhage.
Helium–oxygen mixture (Heliox): Usedinasthma andsevere bronchospasm. Usually, a mixture of
70%–80%heliumand20%–30%oxygen.Theoreticallydecreasesairwayresistanceowingtoitslow
density,leadingtoimprovementintheratiooflaminartoturbulentflow,therebydecreasingtheworkof
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breathing.Studieshavesuggestedsomebenefitinpatientswithsevereasthmaexacerbations.
22
ConsiderationsinAcuteRespiratoryDistressSyndrome
Fluids: Conservative fluid management (pulmonary capillary wedge pressure <8, central venous
pressure[CVP]<4)inanARDSpatientisassociatedwithshortermechanicalventilationtime.
23
Steroids:TheuseofglucocorticoidslaterinthecourseofARDS(≥14days)isnotbeneficialandmay
be harmful. The use of glucocorticoids earlier in the course of ARDS is less clear, but, generally
speaking,thereis nogoodevidenceofbenefit.Steroidsareoftenavoided owing totheirdetrimental
sideeffects,particularlywhenusedtogetherwithparalytics.
24
One notableexceptioninvolvespatientswith severe COVID-19.Ina meta-analysis ofseventrials
thatincluded1703criticallyillpatientswithCOVID-19,glucocorticoidsreduced28-daymortality
comparedwithstandardcareorplacebo.Theywerenotassociatedwithanincreasedriskofsevere
adverseevents.
25
Paralysis: Decreases oxygen consumption from accessory inspiratory muscle use and is frequently
usedinARDS.Dataregardingtheirbenefitareconflicting.
A randomized controlled multicenter trial showed that early neuromuscular blockade with
cisatracuriumwasassociatedwithanimprovementin90-daymortalityandfewerventilatordaysin
patientswithPaO2/FIO2<120mmHg.
26
However,asecondRCTfrom2019withcisatracuriumdoneinpatientswithP:F<150mmHgdid
not result in lower in-hospital mortality, ventilator-free days, or rates of baurotrauma when
comparedwithpatientsreceivinglightsedation.
27
Pronepositioning: Improves oxygenation inpatients withARDS byreducing V/Q mismatching and
improvingshuntingbydecreasingtheamountofatelectaticlung.
EarlyapplicationofpronepositioningisassociatedwithimprovedmortalityinpatientswithARDS
withaPaO2/FIO2<150mmHgARDS.
28
Patientsshouldreceiveneuromuscularblockadetotolerateproning.
Absolute contraindications to proning include spinal instability or unstable fractures. Use of
vasopressors, renal replacement therapy, and obesity are not contraindications to proning, but
obesitycanmakeproningchallenging.
Patientsshouldremainpronedforatleast16consecutivehoursatatimeforbenefitandtolimitthe
frequencyofturns.
Extracorporeal membrane oxygenation (ECMO): Veno-venous ECMO provides gas exchange in
patientswithARDSregardlessoftheextentoftheirlungpathology.Onestudyfoundthatreferraltoa
hospital that provides ECMO was associated with improved survival in patients with ARDS from
H1N1 influenza.29 However, this study was limited by the fact that care likely differed between
hospitalsthatprovideECMOandthosethatdonot.Arecentstudyfoundthatmortalitydidnot differ
between patients with severe ARDS who received early ECMO as compared with patients who
received conventional therapywith ECMOusedas a rescuetherapy.30 ECMO remains an important
optionforcarefullyselectedpatientswithsevereARDSwhoarefailingconventionaltherapy.
CommonComplicationsofMechanicalVentilation
Airwaymalpositioningandocclusion:See“AirwayManagementandEndotrachealIntubation.”
Troubleshootingventilatoralarms:SeeFigure8-2.
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Figure 8-2 Troubleshooting ventilator alarms: what to do when the patient is hypoxic.Auto-PEEP, auto–positive end-
expiratorypressure.
Auto-PEEP: Occurs when inspiration is initiated before complete exhalation is complete. May be
detected on physical examination by wheezing that does not terminate before the next breath.
Demonstrated onventilator flow-time loop byflow notreturning to baseline before delivery ofnext
breath (Figure 8-1). Excessive auto-PEEP can lead to cardiac decompensation owing to tension
pneumothorax–likephysiology.Treatedbyadjusting ventilatorsettingstoprolong theexpiratorytime
(either byincreasing the flow or decreasing the respiratory rate) andtreatingany reversible airway
obstruction.Intheacutesetting,thepatientmayneedtobedisconnectedfromtheventilatortoallowfor
fullexhalation.
Barotrauma/volutrauma: Occurswhen excessive PEEP, inspiratorypressures, or tidal volumes are
applied, resulting in alveolar rupture and dissection of air along interstitial tissues causing
pneumothorax, pneumomediastinum, pneumopericardium, or pneumoperitoneum. If undetected, can
resultinlife-threateningcardiacdecompensation.
Ventilator-associatedpneumonia(VAP):Definedaspneumonia inapatientwhohasbeenintubated
for>48hours.
VAP isgenerallyidentifiedbyanewinfiltrateonCXRinadditionto≥2 ofthefollowingcriteria:
fever,leukocytosis,worseningoxygenation,andpurulentsecretions.
When VAP is suspected, microbiologic specimens should be obtained via tracheal aspirate or
bronchoscopywithbronchoalveolarlavage.
Treatmentwithbroad-spectrumempiricantibioticsbasedonthelocalprevalenceofpathogensand
antibioticsensitivitiesshouldbeinitiatedifthereishighclinicalsuspicionforVAP.Ifanorganism
hasbeenidentified,theantibioticchoiceshouldbetailoredtothespecificpathogen.Generally,the
twomostcommoncausesofVAPareStaphylococcusaureusandPseudomonasaeruginosa.
TheantibioticdurationforVAPisgenerally7days,aslongerdurationsarenotmoreeffectiveand
mayincreasetheriskofantibioticresistance.
31,32
Stress-induced peptic ulcer disease: Critically ill patients are at an increased risk of developing
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