Learning from Fictional Detectives for Better Diagnostic Skills
A General Internal
Medicine Production
Learning from the detectives
Goals
Apply lessons learned from fictional
detectives to the diagnostic process
What did they say, and how can we use
that to become better diagnosticians
"The problem with
putting two and two
together is that
sometimes you get
four, and sometimes
you get twenty-two."
Dashiell Hammett
(
The Thin Man
)
Think of Sherlock
Classic Sherlock
Observation
Deduction – type 2 thinking
Patient #1
–
the story
55 year old man brought to the ED for
confusion
Wife states that he became progressively
confused over 2 days
His blood glucose measured > 800
No acidosis, normal anion gap
Admitted to ICU
Further history
Patient’s VA records from California (he had just
moved to Birmingham) documented type 2 DM
He was prescribed 24 units long acting insulin with 5
units short acting with each meal
He told the ICU physicians that he only took 12 units
daily & morning 5 units
ICU course
Urine drug screen + for cocaine
Urine drug screen + for cocaine
Blood glucose decreased rapidly
Blood glucose decreased rapidly
2 episodes of hypoglycemia
2 episodes of hypoglycemia
HgbA1c > 14
HgbA1c > 14
Then transferred to the floor
Then transferred to the floor
Problem Representation
…
early step is the creation of the
mental abstraction or
“problem
“problem
representation”
representation”
usually as a one-
sentence summary defining the
specific case in abstract terms
Bowen, Judith L. "Educational strategies to promote clinical
diagnostic reasoning." New England Journal of Medicine 355.21
(2006): 2217-2225.
Initial problem representation
55 year old man, cocaine positive,
55 year old man, cocaine positive,
poor diabetes control, poorly
poor diabetes control, poorly
adherent admitted with
adherent admitted with
hyperosmolar state
hyperosmolar state
Implications
Several factors in this problem representation might
influence our thought process
–
The patient has a diagnosis of Type II DM
–
He does not adhere to recommended treatment
–
He uses illegal substances
Thus, we have several potential reasons for his
markedly elevated blood sugar
Problem Representation #2
On discharge from the ICU to the floor:
On discharge from the ICU to the floor:
55 year old man, with brittle
55 year old man, with brittle
diabetes, cocaine positive
diabetes, cocaine positive
IMPLICATIONS OF PROBLEM
Representation
#2
Brittle diabetes
Brittle diabetes
raises some interesting
raises some interesting
questions
questions
We wonder
We wonder
:
:
–
Why is the patient with Type II DM on
Why is the patient with Type II DM on
insulin and no oral agents?
insulin and no oral agents?
–
Why does he so easily develop
Why does he so easily develop
hypoglycemia? (old VA records confirm)
hypoglycemia? (old VA records confirm)
Morning Rounds at the bedside
The patient is very thin
The patient is very thin
–
–
BMI 13
BMI 13
He has had diabetes for 6 years
He has had diabetes for 6 years
He thinks he took metformin at one time
He thinks he took metformin at one time
No evidence of infection or CAD
No evidence of infection or CAD
Problem
representation #3
Very thin man with brittle type II
Very thin man with brittle type II
diabetes for 6 years
diabetes for 6 years
Implications of problem
representation #3
When we try to match this problem
When we try to match this problem
representation against the
representation against the
illness script
illness script
of
of
DM Type II, we have too many features
DM Type II, we have too many features
that do not fit
that do not fit
Therefore, we decide that we need to
Therefore, we decide that we need to
consider other possibilities to explain his
consider other possibilities to explain his
diabetes
diabetes
Illness scripts
Features present (or absent) to match against
Features present (or absent) to match against
our problem representation
our problem representation
Example – CAP
Example – CAP
–
Short duration of symptoms
Short duration of symptoms
–
productive cough
productive cough
–
fever, sweats &/or rigors
fever, sweats &/or rigors
–
abnormal chest exam
abnormal chest exam
–
Compatible CXR
Compatible CXR
DM Type II Illness
script
Usually overweight or obese
Usually overweight or obese
Diabetes usually controlled with oral agents
Diabetes usually controlled with oral agents
at 6 years
at 6 years
Rare episodes of hypoglycemia (since
Rare episodes of hypoglycemia (since
patients have insulin resistance)
patients have insulin resistance)
Our thought process
Since our patient does have brittle diabetes he
Since our patient does have brittle diabetes he
could have LADA
could have LADA
(
(
Latent autoimmune diabetes
Latent autoimmune diabetes
of adults
of adults
)
)
But they also develop ketoacidosis
But they also develop ketoacidosis
–
–
and yet with
and yet with
a BS of 800 he had no ketoacidosis!
a BS of 800 he had no ketoacidosis!
Given his low BMI, we considered the possibility of
Given his low BMI, we considered the possibility of
pancreatic diabetes
pancreatic diabetes
Back to the patient
Not previously documented:
Not previously documented:
2 or more episodes of acute
2 or more episodes of acute
pancreatitis in the past
pancreatitis in the past
Partial pancreatectomy (by his
Partial pancreatectomy (by his
history) at a private hospital
history) at a private hospital
Steatorrhea for 6 years
Steatorrhea for 6 years
Final problem representation
Very thin man, with brittle
Very thin man, with brittle
diabetes for 6 years starting after
diabetes for 6 years starting after
a partial pancreatectomy who also
a partial pancreatectomy who also
has steatorrhea
has steatorrhea
Implications of final problem
representation
Revised diagnosis
Revised diagnosis
–
–
pancreatic
pancreatic
diabetes secondary to partial
diabetes secondary to partial
pancreatectomy with both exocrine
pancreatectomy with both exocrine
and endocrine deficiency
and endocrine deficiency
This complicates his treatment, but
This complicates his treatment, but
perhaps pancreatic enzymes will
perhaps pancreatic enzymes will
help him
help him
Harry Bosch
by Michael Connelly
Think of Bosch
Persistence
Reviewing the old records – looking for a
missed clue
Discussing with a friend
Harry Bosch
Harry Bosch
“I’ve learned over the years that sometimes
if you ask the same question more than
once you get different responses.”
The case of the young woman with
mysterious C diff diarrhea
Harry Bosch
I didn’t have all the answers but experience
I didn’t have all the answers but experience
told me that they would come.
told me that they would come.
The man with “CAP” who did not improve
The man with “CAP” who did not improve
with antibiotics.
with antibiotics.
Persistence!
Persistence!
Patient presentation
41-year-old Hispanic man (left Mexico 7
yrs ago) presents with 4 day h/o
progressive dyspnea and fevers
No previous illness
Clear sputum with occasional blood
streaks
Feels well other than dyspnea
Denies orthopnea or PND
Physical Exam
T 101 P 140 BP 140/85 RR 22 O
2
sat 91%
Decreased breath sounds on the right
Heart exam – tachycardia, no murmurs,
rubs or gallops
No peripheral edema
Routine labs
CXR
Diagnosis?
How would you treat the patient?
Do you need more information?
New
attending physician
Day 9
–
patient has had several courses of
antibiotics and many tests for a variety of
infections
Comparison of PA films
Other clues
Hgb slowly decreasing and after
10 days is
less than 8 (from 10.4)
Patient is expectorating blood
Now has iron deficiency anemia
Bronchoscopy result
Fresh RBC
BAL RBC 206 million
BAL WBC 14 million
Lab changes
Serum creatinine had increased from 0.8
Serum creatinine had increased from 0.8
to 1.2
to 1.2
Looked for the urinalysis but alas
Looked for the urinalysis but alas
Not originally obtained
Not originally obtained
180 RBC no casts
180 RBC no casts
Granulomatosis with polyangiitis
The hidden
clue
Bosch asks a
colleague to look at a
video
When stumped
–
talk
with a colleague or
consultant
“You have a
“You have a
solution that you
solution that you
like, but you are
like, but you are
choosing to ignore
choosing to ignore
anything that you
anything that you
see that doesn't
see that doesn't
comply with it.
comply with it.
"
"
– from the Blind
– from the Blind
Banker – Sherlock
Banker – Sherlock
Season 1 Episode 2
Season 1 Episode 2
•
In making diagnoses (really diagnostic
In making diagnoses (really diagnostic
decisions) we start with system 1
decisions) we start with system 1
•
When we think that system 1 is failing,
When we think that system 1 is failing,
we resort to system 2
we resort to system 2
•
So what do we mean by system 1 and
So what do we mean by system 1 and
system 2
system 2
The Dual Process theory of
cognition
System 1 - Experiential
System 1 - Experiential
Intuitive
Intuitive
Tacit
Tacit
Experiential
Experiential
Pattern recognition
Pattern recognition
Matching against
Matching against
illness script
illness script
Dual process theory
System 1 - Experiential
Intuitive
Tacit
Experiential
Pattern recognition
Matching against
illness script
System 2 - Analysis
System 2 - Analysis
Analytic
Analytic
Deliberate
Deliberate
Rational
Rational
Careful analysis
Careful analysis
Consider a wide
Consider a wide
differential
differential
Dual process theory
Not Independent!!!
“It often seems to me that’s all
detective work is, wiping out
your false starts and beginning
again.”
”Yes, it is very true, that. And it
is just what some people will not
do. They conceive a certain
theory, and everything has to fit
into that theory.
If one little fact will not fit it,
they throw it aside. But it is
always the facts that will not fit
in that are significant.”
― Agatha Christie, Death on the
Nile
•
56-year-old man admitted for 4 days of progressive
dyspnea
•
Minimal cough – 2 episodes of clear pink tinged sputum
•
Denies fever, rigors, has felt chilly
•
No upper respiratory tract symptoms
•
Routine labs unremarkable
•
CXR:
Discarding an admission dx
EMERGENCY DEPT
EMERGENCY DEPT
56-year-old man
with progressive
dyspnea and a left
upper lobe infiltrate
56-year-old man
with progressive
dyspnea, but no
purulent sputum,
no fever and no
rigors
INTERNAL MEDICINE TEAM
INTERNAL MEDICINE TEAM
Two problem representations
•
Community acquired pneumonia
•
Housestaff remained skeptical
•
proBNP = 900
•
Echocardiogram order
Admission diagnosis
•
Left ventricular ejection fraction ~ 30 %
•
Increased pulmonary artery pressure
Echocardiogram
results
•
LVEF = 20%
with dilated cardiomyopathy
•
Mild CAD – approximately 40% in each artery
•
Left atrial enlargement
•
PCWP = 30
•
PAP = 64/38
Cardiac catheterization
•
36 hours later – progressive dyspnea on exertion
for at least 2 months
•
History of hypertension – untreated
•
Cardiac exam – loud summation gallop
Further history & physical
•
Incomplete data collection – proper history not
taken
•
Radiologist read the X-ray as infiltrate – did not
notice the cardiomegaly
•
Inadequate physical exam skills
•
Diagnostic inertia
Why such dx errors?
“The world is full of obvious
things which nobody by any
chance ever observes.”
― Arthur Conan Doyle, The
Hound of the Baskervilles
•
82 yo woman admitted to ICU for UGI bleed
82 yo woman admitted to ICU for UGI bleed
•
Endoscopy showed esophageal ulcer
Endoscopy showed esophageal ulcer
•
Transfused and volume repleted
Transfused and volume repleted
•
Monday morning transferred at 7 am
Monday morning transferred at 7 am
•
Rounds start at 7:45 am
Rounds start at 7:45 am
•
Intern briefly sees the patient – reports that she
Intern briefly sees the patient – reports that she
is stable
is stable
The July patient
Basic Metabolic Panels
Monday
morning
Original BMP
The Question
Why is the bicarbonate 17?
Why is the bicarbonate 17?
Analyze the possibilities
Calculate normal gap
Assume metabolic acidosis
Does metabolic acidosis fit the
patient?
Is this a normal gap metabolic
acidosis
Could it be bicarbonate loss?
–
No diarrhea or acetazolamide
Could it be a renal acidosis?
–
Normal renal function
–
Appeared quickly – distal RTA
unlikely
Could it be dilution
acidosis?
–
Literature suggests minimal HCO
3
decreases
‘Eliminate all other factors, and the one
which remains must be the truth.’
- Arthur Conan, Doyle, The Sign of the Four
- Arthur Conan, Doyle, The Sign of the Four
What remains?
If not a metabolic acidosis?
If not a metabolic acidosis?
Could
Could
it be a respiratory alkalosis?
it be a respiratory alkalosis?
Therefore
Therefore
–
Need ABG and further clinical
Need ABG and further clinical
investigation
investigation
“Data! Data! Data!” he cried
impatiently. “I can’t make bricks
without clay.”
- Arthur Conan Doyle, The Adventure
of the Copper Beeches
The data
Weight gain – 12 # since admission
Weight gain – 12 # since admission
New small bilateral
New small bilateral
pleural effusions
pleural effusions
Order pro-BNP
Order pro-BNP
R
R
eceiving 200 cc NS per hour
eceiving 200 cc NS per hour
Resolution
Stopped IV fluids
Stopped IV fluids
Gave one dose of furosemide
Gave one dose of furosemide
ABG 7.43/29/79/19 on 3 l O
ABG 7.43/29/79/19 on 3 l O
2
2
proBNP >4000
proBNP >4000
Pt lost 8 # & her nasal oxygen
Pt lost 8 # & her nasal oxygen
•
Learners want to learn
Learners want to learn
how and why
how and why
we
we
make decisions
make decisions
•
Facts are retrievable
Facts are retrievable
•
Therefore we must teach diagnostic
Therefore we must teach diagnostic
reasoning every day on rounds, consults
reasoning every day on rounds, consults
and in the clinic
and in the clinic
•
Wisdom trumps knowledge
Wisdom trumps knowledge
Understanding cognition and
medical education
•
Remember that experts have more refined
Remember that experts have more refined
illness scripts and problem representation
illness scripts and problem representation
•
Therefore, we are trying to help our learners
Therefore, we are trying to help our learners
know when System 1 is adequate and when to
know when System 1 is adequate and when to
move to System 2
move to System 2
•
As learners progress they should spend more
As learners progress they should spend more
time in System 1
time in System 1
•
They will get there faster if we are
They will get there faster if we are
explicit in explaining the clues and cues
explicit in explaining the clues and cues
What should we be teaching?
•
Deliberate practice – keep track of
patients – find out what happens to
them
•
Attend morning reports – think carefully
about the diagnostic processes
•
Reinforce what you learn about complex
patients with focused reading
What should students and
residents do?
Explore the application of lessons from fictional detectives like Sherlock Holmes to enhance diagnostic processes in medicine. Delve into problem representation, observation, deduction, and clinical reasoning strategies to improve diagnostic accuracy and patient care.
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Presentation Transcript
Learning from the detectives A General Internal Medicine Production
Goals Apply lessons learned from fictional detectives to the diagnostic process What did they say, and how can we use that to become better diagnosticians
"The problem with putting two and two together is that sometimes you get four, and sometimes you get twenty-two." Dashiell Hammett (The Thin Man)
Classic Sherlock Observation Deduction type 2 thinking
Patient #1 the story 55 year old man brought to the ED for confusion Wife states that he became progressively confused over 2 days His blood glucose measured > 800 No acidosis, normal anion gap Admitted to ICU
Further history Patient s VA records from California (he had just moved to Birmingham) documented type 2 DM He was prescribed 24 units long acting insulin with 5 units short acting with each meal He told the ICU physicians that he only took 12 units daily & morning 5 units
ICU course Urine drug screen + for cocaine Blood glucose decreased rapidly 2 episodes of hypoglycemia HgbA1c > 14 Then transferred to the floor
Problem Representation early step is the creation of the mental abstraction or problem representation usually as a one- sentence summary defining the specific case in abstract terms Bowen, Judith L. "Educational strategies to promote clinical diagnostic reasoning." New England Journal of Medicine 355.21 (2006): 2217-2225.
Initial problem representation 55 year old man, cocaine positive, poor diabetes control, poorly adherent admitted with hyperosmolar state
Implications Several factors in this problem representation might influence our thought process The patient has a diagnosis of Type II DM He does not adhere to recommended treatment He uses illegal substances Thus, we have several potential reasons for his markedly elevated blood sugar
Problem Representation #2 On discharge from the ICU to the floor: 55 year old man, with brittle diabetes, cocaine positive
IMPLICATIONS OF PROBLEM Representation #2 Brittle diabetes raises some interesting questions We wonder: Why is the patient with Type II DM on insulin and no oral agents? Why does he so easily develop hypoglycemia? (old VA records confirm)
Morning Rounds at the bedside The patient is very thin BMI 13 He has had diabetes for 6 years He thinks he took metformin at one time No evidence of infection or CAD
Problem representation #3 Very thin man with brittle type II diabetes for 6 years
Implications of problem representation #3 When we try to match this problem representation against the illness script of DM Type II, we have too many features that do not fit Therefore, we decide that we need to consider other possibilities to explain his diabetes
Illness scripts Features present (or absent) to match against our problem representation Example CAP Short duration of symptoms productive cough fever, sweats &/or rigors abnormal chest exam Compatible CXR
DM Type II Illness script Usually overweight or obese Diabetes usually controlled with oral agents at 6 years Rare episodes of hypoglycemia (since patients have insulin resistance)
Our thought process Since our patient does have brittle diabetes he could have LADA (Latent autoimmune diabetes of adults) But they also develop ketoacidosis and yet with a BS of 800 he had no ketoacidosis! Given his low BMI, we considered the possibility of pancreatic diabetes
Back to the patient Not previously documented: 2 or more episodes of acute pancreatitis in the past Partial pancreatectomy (by his history) at a private hospital Steatorrhea for 6 years
Final problem representation Very thin man, with brittle diabetes for 6 years starting after a partial pancreatectomy who also has steatorrhea
Implications of final problem representation Revised diagnosis pancreatic diabetes secondary to partial pancreatectomy with both exocrine and endocrine deficiency This complicates his treatment, but perhaps pancreatic enzymes will help him
Harry Bosch by Michael Connelly
Think of Bosch Persistence Reviewing the old records looking for a missed clue Discussing with a friend
Harry Bosch I ve learned over the years that sometimes if you ask the same question more than once you get different responses. The case of the young woman with mysterious C diff diarrhea
Harry Bosch I didn t have all the answers but experience told me that they would come. The man with CAP who did not improve with antibiotics. Persistence!
Patient presentation 41-year-old Hispanic man (left Mexico 7 yrs ago) presents with 4 day h/o progressive dyspnea and fevers No previous illness Clear sputum with occasional blood streaks Feels well other than dyspnea Denies orthopnea or PND
Physical Exam T 101 P 140 BP 140/85 RR 22 O2sat 91% Decreased breath sounds on the right Heart exam tachycardia, no murmurs, rubs or gallops No peripheral edema
Routine labs CBC BMP WBC 13k 135 97 12 128 Hgb 10.4 4.1 27 0.8 8.6 Hct 31.2 Plt 325 84% N, 10% L
Diagnosis? How would you treat the patient? Do you need more information?
New attending physician Day 9 patient has had several courses of antibiotics and many tests for a variety of infections
Other clues Hgb slowly decreasing and after 10 days is less than 8 (from 10.4) Patient is expectorating blood Now has iron deficiency anemia
Bronchoscopy result Fresh RBC BAL RBC 206 million BAL WBC 14 million
Lab changes Serum creatinine had increased from 0.8 to 1.2 Looked for the urinalysis but alas Not originally obtained 180 RBC no casts
The hidden clue Bosch asks a colleague to look at a video When stumped talk with a colleague or consultant
You have a solution that you like, but you are choosing to ignore anything that you see that doesn't comply with it." from the Blind Banker Sherlock Season 1 Episode 2
The Dual Process theory of cognition In making diagnoses (really diagnostic decisions) we start with system 1 When we think that system 1 is failing, we resort to system 2 So what do we mean by system 1 and system 2
Dual process theory System 1 - Experiential Intuitive Tacit Experiential Pattern recognition Matching against illness script
Dual process theory System 2 - Analysis Analytic Deliberate Rational Careful analysis Consider a wide differential System 1 - Experiential Intuitive Tacit Experiential Pattern recognition Matching against illness script
Not Independent!!! System1 System 2
It often seems to me thats all detective work is, wiping out your false starts and beginning again.
Yes, it is very true, that. And it is just what some people will not do. They conceive a certain theory, and everything has to fit into that theory.
If one little fact will not fit it, they throw it aside. But it is always the facts that will not fit in that are significant. Agatha Christie, Death on the Nile
Discarding an admission dx 56-year-old man admitted for 4 days of progressive dyspnea Minimal cough 2 episodes of clear pink tinged sputum Denies fever, rigors, has felt chilly No upper respiratory tract symptoms Routine labs unremarkable CXR:
Two problem representations EMERGENCY DEPT 56-year-old man with progressive dyspnea and a left upper lobe infiltrate INTERNAL MEDICINE TEAM 56-year-old man with progressive dyspnea, but no purulent sputum, no fever and no rigors
Admission diagnosis Community acquired pneumonia Housestaff remained skeptical proBNP = 900 Echocardiogram order
