Medical Decision-Making
Keith Bradley, MD
Director
Research Associates Program at St. Vincent’s
National Alliance of RA Programs
Three (3) Modes of Diagnosis
• Pattern Recognition (“Augenblick”)
• Branching
• Matching
Augenblick
“blink of an eye”
See it; know it
ABC’s
• A = asymmetric
• B = border irregular
• C = color black or variable
• D = diameter > 1/4”
Branching
Branching
e.g., Chest Pain
Branching
e.g., Chest Pain
• “expert”
Branching
e.g., Chest Pain
• “expert”
• “blinders”
Branching
e.g., Chest Pain
• “expert”
• “blinders”
•  potential for error
Branching
e.g., Chest Pain
• “expert”
• “blinders”
•  potential for error
• “practice”
Matching
Matching
• ALL possible diagnoses on x-axis
Matching
• ALL possible diagnoses on x-axis
• Each possible
– symptom
– sign
– investigation result
on y-axis
Matching
• ALL possible diagnoses on x-axis
• Each possible sx, px, tx on y-axis
• = Excel spreadsheet
Matching
• ALL possible diagnoses on x-axis
• Each possible diagnoses on y-axis
• = Excel spreadsheet
• Lawrence Weed, MD / “couplers”
Different Types of Problems 
Different Types of Responses
Non-Traumatic Unconsciousness
Non-Traumatic Unconsciousness
• Airway
Non-Traumatic Unconsciousness
• Airway
• Breathing
Non-Traumatic Unconsciousness
• Airway
• Breathing
• Circulation
Non-Traumatic Unconsciousness
•
•
•
•
Airway
Breathing
Circulation
Defibrillate
Types of Problems 
Types of Responses
Problem
Acute
Response

Rapid, simple, memorized
Fever, Ear Pain in a 3 year old
Fever, Ear Pain
Fever, Ear Pain
Fever, Ear Pain
• Dx = acute otitis media
• Tx = depending on timing: nothing or Abs
Types of Problems 
Types of Responses
Problem
Acute
Response

Routine 
Rapid, simple, memorized
Routine, stylized
“My leg is swollen”
“My leg is swollen”
• What would Dr. House do?
“My leg is swollen”
• What would Dr. House do?
• DDx
“My leg is swollen”
• What would House do?
• DDx
• Key Question … never forget to ask = ?
“My leg is swollen”
•
•
•
•
What would House do?
DDx
Key Question … never forget to ask
Be the star!
“My leg is swollen”
•
•
•
•
What would House do?
DDx
Key Question … never forget to ask
Be the star!
– thick smear … draw blood at night
“My leg is swollen”
• Dx = filiariasis
“My leg is swollen”
• Dx = filiariasis
• Tx = anti-helminths or …
“My leg is swollen”
• Dx = filiariasis
• Tx = anti-helminths or …
– The parasites responsible for filariasis have a
population of symbiotic bacteria, Wolbachia, that
live inside the worm.
– When the symbiotic bacteria are killed by the
antibiotic, the worms themselves also die.
• Doxycycline might be effective
– Clinical trials in June 2005 by the Liverpool School
of Tropical Medicine reported that an 8 week course
almost completely eliminated microfilariaemia.[4][5]
Types of Problems 
Types of Responses
Problem
Acute

Response
Rapid, simple, memorized
Routine 
Routine, stylized
Unique 
Unique
MVC, Multiple Trauma
Types of Problems 
Types of Responses
Problem
Response
Acute

Rapid, simple, memorized
Routine

Routine, stylized
Unique

Unique
Complex 
Complex