a teaching hospital of harvard medical school how...
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HowIntensivistsThink
CriticalThinkingStrategiestoMinimize
CognitiveErrorsintheICU
RichardM.Schwartzstein,MD
EllenandMelvinGordonProfessorofMedicineandMedicalEducation
AssociateChief,DivisionofPulmonaryandCriticalCareMedicine
Director,ShapiroInstituteforEducationandResearch
Director,EducationScholarship,HarvardMedicalSchool
A teaching hospital of
Harvard Medical School
Education is at the heart of patient care.
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A teaching hospital of
Harvard Medical School
Disclosures
Ihavenofinancialdisclosuresrelevanttothe
contentofthispresentation.
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A teaching hospital of
Harvard Medical School
Whatdirectionarewedriving?
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A teaching hospital of
Harvard Medical School
Sometimes,signshelp;othertimes…
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A teaching hospital of
Harvard Medical School
….signscanbeconfusing
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A teaching hospital of
Harvard Medical School
Case1
60yearoldmanarrivedisadmittedtotheICUwith
alteredmentalstatus(somnolent),smelledof
alcohol,driedemesisonhisshirt.Diminishedbreath
soundsbilaterally.
O2sat91%;ABG(21%O2):7.24/60/65
CXRmachineisnotavailable.
Resident:“Iwanttostartantibioticsforhis
aspiration.”
Yourresponse….
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A teaching hospital of
Harvard Medical School
Case1
1. Notallaspirationsrequire
antibiotics
2. Waitforafever
3. Hedidn’taspiratesignificantly
4. WaitforthechestX-ray
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A teaching hospital of
Harvard Medical School
Case1
1. Notallaspirationsrequire
antibiotics
2. Waitforafever
3. Hedidn’taspiratesignificantly
4. WaitforthechestX-ray
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A teaching hospital of
Harvard Medical School
Howdoyouthinkabouthypoxemia?
• Howdoyouthinkaboutthephysiologicalcausesof
hypoxemia(decreasedPiO2,alveolarhypoventilation,
V/Qmismatch,shunt,diffusionabnormality)?
• Isthereanabnormalalveolartoarterialoxygen
gradient?
O2sat91%;ABG(21%O2):7.24/60/65
NormalA-aDO2;hypoventilationiscauseofhypoxemia.
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A teaching hospital of
Harvard Medical School
Today’sObjectives:Attheendofthis
session,youshouldbeableto…
• Definetheelementsofcriticalthinkingandthedualprocessing
modelusedtodescribehowweapproachproblems
• Describecontributionofcognitivebiastoclinicalerrors
• Distinguishhypotheticaldeductivereasoning,commonlyusedin
clinicalpractice,frominductivereasoning,whichmaybeless
subjecttocognitivebiases
• Explaintheroleofuncertaintyinclinicalreasoning
• **Forthoseofyouwhoteach,describestrategiesforhelping
yourlearnerdevelopcriticalthinkingskills
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A teaching hospital of
Harvard Medical School
Whatiscriticalthinking?
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A teaching hospital of
Harvard Medical School
AnExperiment
Takeoutapieceofpaper….
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A teaching hospital of
Harvard Medical School
Whoisthis?
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A teaching hospital of
Harvard Medical School
WRITEDOWNYOURANSWER
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A teaching hospital of
Harvard Medical School
Whoisthis?
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A teaching hospital of
Harvard Medical School
WRITEDOWNYOURANSWER
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A teaching hospital of
Harvard Medical School
TheLimitsofPatterns
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A teaching hospital of
Harvard Medical School
Whatisthediagnosis?
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A teaching hospital of
Harvard Medical School
NeuralActivationofPatternRecognitionMeloM,etal.,PLoSONE6(12):e28752, 2011
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A teaching hospital of
Harvard Medical School
YourExperienceofMedicalSchool?
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A teaching hospital of
Harvard Medical School
FocusofEducation
Educationinuniversitiesinthefuture“willbemore
abouthowtoprocessanduseinformationand
lessaboutimpartingit.…inaworldwherethe
entireLibraryofCongresswillsoonbeaccessible
onamobiledevice…factualmasterywillbecome
lessandlessimportant.”
LarrySummers,NYTimes,Jan22,2012
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A teaching hospital of
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Thinking!
upthebarconsulting.com
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A teaching hospital of
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Uncertainty
“Asfarasthelawsofmathematics referto
reality, theyarenotcertain;andasfaras
theyarecertain, theydonotrefertoreality.”
---AlbertEinstein
“Allunderstanding isprovisionalandsubject
tocontinualadjustment.”
--- AtulGawande
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A teaching hospital of
Harvard Medical School
TheBrainHatesUncertainty
(andcanleadtocognitivebias)
“Themindisdesignedtomakethebest
possiblecaseforagiveninterpretation
ratherthanrepresentalltheuncertainty
aboutagivensituation.”
--- AmosTversky
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A teaching hospital of
Harvard Medical School
Howwethink…DualProcessing
• Consciousthought
• Unconsciousthought
–CognitiveBiasesCOPYRIGHT
A teaching hospital of
Harvard Medical School
JudgmentUnderUncertaintyTverskyandKahneman,Science,1974
“…peoplerelyonalimited
numberofheuristicprinciples
whichreducethenumberof
complextasksofassessing
probabilities…tosimpler
judgmentaloperations”which
can“leadtosevereand
systemicerrors.”
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A teaching hospital of
Harvard Medical School
DualProcessingModelofThinking
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A teaching hospital of
Harvard Medical School
Inductivevs.deductivereasoning
• Mostdoctorslearnthehypothetico-deductive
approachtopatientcare-- clinicalreasoning
– Withafew“facts”createadifferentialdx
– Statewhatyouknowaboutthosediagnoses
andseehowwellthedatafit.
• Inductiveapproach(taughttoengineers)– critical
thinking
– Create“basic”ormechanistichypotheses
beforecreatingddx
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ThinkingApproaches
Hypothetico-deductive
FewFacts
ê
DifferentialDX
ê
Deducewhatyouknowabout
diseases
ê
Matchpatienttodiseases
Inductive
Collectmanyfacts
ê
Mechanistichypotheses
ê
Morefacts;test
hypotheses
ê
Finaldiagnosis
Potter et al. Med Ed 2010
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A teaching hospital of
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ClinicalReasoning:OverlappingConcepts
Inductive
Thinking
Hypothetico-
deductive
Reasoning
EBMClinical
Epidemiology
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Diagnosisvs.Hypothesis
• Diagnosis: “theactofidentifyingadisease
fromitssignsandsymptoms”
• Hypothesis: “atentative assumptionmade
inordertodrawoutandtestitslogicalor
empiricalconsequences”
Merriam-Webster dictionary
Doesitmatterwhichwordyouuse?
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DiagnosticMalpracticeCases
Themajorityofdiagnosticmalpractice
cases(misseddiagnoses)donotinvolve
esotericcases;rather,theyaredueto
commondiagnosesthatwerenot
consideredbythedoctor….i.e.,theyare
theconsequenceofthinkingproblems
notknowledgeproblems.
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A teaching hospital of
Harvard Medical School
Aphonecallatnight….PatientwithhxofCADandHFrEFadmitted2daysago
withbleedingulcer.Endoscopyshowedlargeulcerin
fundus:visiblevesselbutnoactivebleeding.Now
patientlightheaded.BP60systolic(baseline110/80).
Extremitiescool;poorcapillaryrefill.Hctstable.
Norepistarted.HR110à 140.NochangeinBP.
Phenylephrineadded.ECG:sinustachy;chronicST-T
wavechanges;moreprominentSTdepression.
“Ithinkthepatientisincardiogenicshockandneeds
urgentcathoranintra-aorticballoonpump.”
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A teaching hospital of
Harvard Medical School
YourAnswer
1. Consultcardiologyandcallmeafter
youspeaktothem.
2. Getanechocardiograminstead.
3. Whydoyouthinkit’scardiogenic
shock?
4. Whyareyoucallingme?
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A teaching hospital of
Harvard Medical School
YourAnswer
1. Consultcardiologyandcallmeafter
youspeaktothem.
2. Getanechocardiograminstead.
3. Whydoyouthinkit’scardiogenic
shock?
4. Whyareyoucallingme?
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A teaching hospital of
Harvard Medical School
InitialReasoning….
• Patienthashistoryofheartproblems;probablyhavinganacuteMI.
• Clinicalexamsuggests SVRishigh,consistentwithcardiogenic shock.
• Hematocrit isstable;Idon’tthinkthisisbleeding.
Youaretheattending.Howdoyourespond?
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A teaching hospital of
Harvard Medical School
Gettheresidentto“worktheproblem”
• Gothebedsidewiththeresident.
• MAP– CVP=QXSVR
• Whatdoyouknowaboutbloodpressurecontrol?HowdoesthathelpyouthinkaboutlowBP?
• Questions:
– Hascontractility,preload,orRVafterloadchanged?
– WhydoesHctfallwithanacuteGIbleed?
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A teaching hospital of
Harvard Medical School
WhatQuestionsDoYouAsk?
• Why?How?Tellmehowyouthinkabout
thisproblem?Drivethelearner(andyourself)
todoinductivereasoning.
• WhatdoyouknowaboutX?
• Worrylessaboutthe“what isthis?”and
moreabout“whyisthishapping?”
• “Youknowmorethanyouthink!”
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A teaching hospital of
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Backtothecase…
Norepinephrinehasn’thelped!I’mafraid
togivefluidsgiventhispatient’shistoryof
heartfailure.Ireallythinksheneedsam
emergentcath.”COPYRIGHT
A teaching hospital of
Harvard Medical School
KnowledgeandCognitiveBiases
• Cognitive biasandcognitivedispositions torespond
• Metacognition:thinkabout howyouarethinking
• Calltheseoutwhenyouseethem
• Availability bias -probabilityassignedbasedoneaseofrecallofspecificexamples
• Confirmationbias -selectivelyacceptingorignoringdata
• Anchoringbias -defendyourposition
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Acad Emerg Med
2002;9:1184-1204
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A teaching hospital of
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Backtothecase…
• ExamshowsflatJVP;no
orthopnea.
• Inotropesaddlittlewhen
LVEDVislow
• Fluidsgiven;blood
orderedfromtheblood
bank.Bloodpressure
improves.Hematocrit
falls6pointswithfluids.
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A teaching hospital of
Harvard Medical School
Skills- Formulationofhypotheses
• Howyouposequestions
– Goingfromtheparticular tothegeneral(induction): “iftheyhaveX(flatJVP),whatisittellingme?”
– Aretheytestable?“IpredictY(improvedBP;lowerHct)willhappen(ifIgivecrystalloid).”
– Revisingwithnewdata
• Identifyingthekeyissues
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ExpertiseandCreativity
www.nwlink.com
Canyoucreatea
solutiontoa
problemyou
haven’t seen
before?
Creating
Evaluating
Analyzing
Applying
Understanding
Remembering
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Routinevs.AdaptiveExpertMylopoulosM,RegehrG.MedEd2007
• RoutineExpert
– Seesnovelproblemandadaptproblemtothesolutionwithwhichtheyarecomfortable
– Characterizedbyspeed,accuracy,automaticity
• AdaptiveExpert
– Usesnewproblemaspointofdepartureforexploration;expandknowledgeandunderstanding
– Characterizedbyinnovation,creativity
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HowDoYouThinkabout
“PhysicalDiagnosis”
• Distinctionbetween“physicalexam”and
“physicaldiagnosis”
• Inductivevs.hypothetico-deductivemodel
ofteachingandlearning
– Cluesvspatterns
– Mechanisms vs.diagnoses
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A teaching hospital of
Harvard Medical School
BedsideEvaluation
Reinforcefundamental
conceptsas
manifestedinphysical
exam(anatomy,
physiol,biochem)
• JVP
• SignsofO2delivery
• CardiacGallops
• Respiratorypatterns
Whatdoesthesign“mean”rather
thanwhatdxisit
• Wheeze=turbulentflow,
narrowedairwayratherthan
“asthma”
• Edema=increasedtotalbody
volume,increasedvenous
pressure,ordecreasedoncotic
pressureratherthan“CHF”
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A teaching hospital of
Harvard Medical School
ConceptMapsGuerrero,AcadMed2001;76:385
• Graphicdevicestorepresentrelationshipsbetweenmultipleconcepts
• Reinforcemechanisticthinking
• Makelinksexplicit
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Pancreatitis
Inflammatoryresponse/
cytokineRelease
Increasedvascular
permeability
Third-spacingIncreasedabdominal
pressures
Decreased
preload
Decreased
CO
Decreasedchest-wall
compliance
Increased
ADH
IncreasedPalv
Increaseddeadspace
IncreasedNa
Decreased
insulin
Hypovolemia Increased
glucose
Decreased
DO2
Increased
sympathetic
activation
IncreasedHR
Increased
anaerobic
metabolism
Increased
lactate
IncreasedPaCO2
Hypotension
Acidemia
Acute
kidney
injury
Decreased
calcium
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Pancreatitis
Inflammatoryresponse/
cytokineRelease
Increasedvascular
permeability
Third-spacingIncreasedabdominal
pressures
Decreased
preload
Decreased
CO
Decreasedchest-wall
compliance
Increased
ADH
IncreasedPalv
Increaseddeadspace
DecreasedNa
Decreased
insulin
Hypovolemia Increased
glucose
Decreased
DO2
Increased
sympathetic
activation
IncreasedHR
Increased
anaerobic
metabolism
Increased
lactate
IncreasedPaCO2
Hypotension
Acidemia
Acute
kidney
injury
Decreased
calcium
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A teaching hospital of
Harvard Medical School
Academic Medicine 2014COPYRIGHT
A teaching hospital of
Harvard Medical School
Milestones• Coreelements
– Metacognition:reflectonone’sthinking;knowledgeof
cognitiveprocesses
– Attitudes:seeksfeedback;curiosity
– Skills:togglebetweensystem1and2;inductive
reasoning;canmakelinkagesbetweenconcepts
• 5Stages
– Unreflective -- Advanced
– Beginning -- Accomplished
– Practical
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A teaching hospital of
Harvard Medical School
Case370year-oldmanadmittedwithfatigue,severaldaysof
nauseaandvomitingandincreasingdyspnea.Noted
chillsathome.HassevereCOPDandmildchronic
kidneyinjury(Creat2).
Exam:mildlyconfused;temp101.ChestwithlargeAP
diameter;diminishedbreathsoundsbilaterally;no
wheeze.JVP8cm.PMInotdisplaced.Nogallop.Abd:
soft,non-tender.Liverandspleennotenlarged.Extrem:
erythemaofrightleg.
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A teaching hospital of
Harvard Medical School
Case3- continued
Labs:
Hct31,WBC10.5
Na135,K5.2,Cl85,HCO325
BUN90,Creat4.5
Shouldyoustartsteroidsandnebulizers?
Otherthoughts?
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A teaching hospital of
Harvard Medical School
“Worktheproblem”
• Gothebedside.
• Howdoyouthinkaboutdyspnea?
• Whydopeopleincreasetheirventilation?
• Howdoyouassess theacid-base statusofthepatient?
• Ifthepatienthyperventilates, whywillthatchangelungvolumesandworkofbreathinginapatientwithCOPD?
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A teaching hospital of
Harvard Medical School
Case3- continued
Labs:
Hct31,WBC10.5
Na135,K5.2,Cl85,HCO325
BUN90,Creat4.5
Whennormalisnot“normal”!
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A teaching hospital of
Harvard Medical School
StrategiesforCriticalThinking
• Askquestionstostimulateinductivereasoningbased
onfundamentalphysiological/pathophysiological
concepts.
• Lookforcognitivebiases;areyou(oryourresident,NP,
etc.)usingSystem1orSystem2thinking?
(metacognition)
• Thinkof“physicaldiagnosis”ratherthanphysicalexam
• Consideruseofconceptmapsiftroublemaking
connectionsbetweendatainhistory,exam,labs.
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A teaching hospital of
Harvard Medical School
Summary• ClinicalReasoning:likelyacontinuumbetweentype1
andtype2thinking
• Fortype2thinkingtobe“faster”,youneedtopractice
it,evenwhenitisnotabsolutelyneeded
• InductivereasoningmayprovidebroaderDDXandless
susceptibilitytocognitivebiases
• Considerclinicalreasoningthatfocusesonhypotheses
ratherthandiagnosesandacknowledgesuncertainty.
• “Conceptmaps”mayhelpyouengageinanalytical
approachestopatientproblems
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