Schemes for Expert Medical Decision Making

1. Secrets of Experts in Clinical
Decision Making: Schemes of
Care
Dr. Imad Salah Ahmed Hassan MD FACP FRCPI MSc MBBS
Consultant Physician & Pulmonologist
Chairman, Knowledge Translation Committee
Department of Medicine
King Abdulaziz Medical City
Riyadh, Saudi Arabia
imadsahassan@yahoo.co.uk

2. Gather Information
Step 1 (History & Physical)

3. Summarize the Case
Step 2 using Technical Language

4. Step 2
• Comprehensive but Concise, Text-book-Like:
• Must contain patient’s name, gender, age,
• occupation, nationality racial/geographic
origin, relevant Past History/Social
History/Family History, Drug/Allergic
History, Symptoms + duration –in technical
terms, Relevant physical signs in technical
conclusive terms.

5. Step 2: Case Presentation Example
• 67 yr old male
• Bird/pigeon breeder, smoker
• 3 days history of fever, cough with yellow sputum, left
stabbing chest pain that is worse with breathing and
coughing and breathlessness
• Clinically, breathless, cyanosed, disoriented to
time, person and place, Temperature 39.1C, BP 86/50, RR
32/min, bilateral coarse crepitations, bronchial breathing
left lower zone.
• Chest x-ray: left basal consolidation

6. Step 2: Case Technical Summary
• 67 year old, smoker and bird-breeder presenting with a 3
days history of productive cough, dyspnea and left
pleuritic chest pains.
• Clinically confused, cyanosed, febrile, tachypnoiec and
hypotensive with signs of left lower zone consolidation.

7. Step 3 Propose a Diagnosis

8. Step 3: Use Bed-side Diagnosis
Schemes
• Pattern-recognition
• Smart Heuristics
• Rule-Out worst Scenario ROWS
• Red Flags (symptoms or signs of more serious
pathology) etc
• Hypothetico-deductive Strategies (from H&P)

9. Step 3: Use Bed-side Diagnosis
Schemes
• High-Fidelity/Reliability Pattern Recognition (spot
diagnosis): Shingles, Acromegalic Facies
• Low-Fidelity/Reliability Pattern Recognition (error-prone):
Central chest pain radiating to the left arm plus sweating, nausea
and vomiting =Acute Coronary Syndrome (other possibilities
still exist!)
• Smart Heuristic “Rules of Thumb”: early morning headache
and vomiting=Increased intracranial pressure
• ROWS: Meningitis, SAH, CVA, Temporal Arteritis etc in a
patient with headache
• Red Flags: rest pain, weight loss, neurological deficits etc in a
patient with low back pain

10. Step 3: Use Bed-side Diagnosis
Schemes
• Hypothetico-deductive Strategies (from H&P)
• Detailed history
• Clues from all components of the history
• Comprehensive physical examination
• May need to revert to investigations if no diagnosis is clear.

11. Step 4 Differential Diagnosis

12. Step 4: Use Differential Diagnosis
Schemes
• Differential Diagnosis Cognitive Aids:
 Anatomical
 Physiological
 Pathological
An important cause of missing a diagnosis is not thinking
of it!!! i.e. not putting a differential diagnosis.

13. Step 4: Use Differential Diagnosis
Schemes
Anatomical Differential Physiological Differential Etio-pathological Differential
Diagnosis Diagnosis Diagnosis
Pain Syndromes: e.g. central Shock: this may be Congenital or Hereditary
chest pain may be categorized hypovolemic, distributive,
as arising from the heart, obstructive or cardiogenic
aorta, esophagus, chest wall
etc
Swellings: e.g. a neck swelling Thrombosis: This may be Acquired:
differential diagnosis will related to a vessel wall 1. Traumatic
include the thyroid, lymph pathology, blood constituents 2. Infective: viral, bacterial
nodes, vascular, skin etc or flow rate. etc
3. Inflammatory/auto-
immune
4. Vascular/degenerative
5. Neoplastic/para-
neoplastic
6. Metabolic/endocrine
7. Drug-induced/ poisoning
8. Deficiency diseases
9. Psychogenic
10. Idiopathic/cryptogenic

14. Step 5 Order Tests (Rationally)

15. Step 5: Pre-test Probability Assessment
for Rational Test Ordering
• Frugal (simple and applicable) Heuristics
Probability Assessment
• Order tests: based on Test
Sensitivity, Specificity and Likelihood
Ratios
• Baye’s may not be a practical and quick pre-test probability assessment
approach!

16. Step 5: Pre-test Probability Assessment
for Rational Test Ordering
• Frugal Pre-test Probability Assessment:
• 1. Strong Risk factor for the condition: Yes/No
• 2. No alternative plausible bed-side Diagnosis: Yes/No
• Interpretation:
 High (2 YES) or
 Intermediate (1 YES 1 NO) or
 Low (2 NO)

17. Step 5: Pre-test Probability Assessment
for Rational Test Ordering
• SpIn: highly specific tests are useful for ruling-in the
diagnosis when positive ( use for high and intermediate
probabilities) e.g. spiral CT for suspected pulmonary
embolism.
• SnOut: highly sensitive tests are useful for ruling-out the
diagnosis when negative ( use for low probabilities) e.g. d-
dimer for suspected pulmonary embolism.

18. Sensitivity
• How often is the test result correct for persons
in whom the disease is known to be present?
SENSITIVITY • Sensitivity - the proportion of people with
disease who have a positive test.
• in a group of 100 patients with bacterial
pneumonia, 80 had a raised C-reactive
Example: protein CRP: the sensitivity of CRP for
diagnosing bacterial pneumonia is thus 80%.

19. Specificity
• How often is the test result correct for persons in
SPECIFICITY whom the disease is known to be absent?
• Specificity - the proportion of people without
the disease who have a negative test.
• in a group of 100 patients without
pneumonia, 10 had a raised C-reactive
Example: protein CRP: the specificity of CRP for
correctly excluding pneumonia is thus 90%.

20. Likelihood Ratio
• the likelihood that a given test result would be
expected in a patient with the target disorder
compared to the likelihood that the same
Likelihood result would be expected in a patient without
that disorder.
• In general, a positive likelihood ratio of 4 or
ratio: more is useful in ruling-in the target
disorder. A negative likelihood ratio of less
than 0.3 is useful in ruling-out the target
disorder.

21. Likelihood Ratio
• Example: A raised Jugular venous
pressure JVP in a patient with a history
Likelihood suggestive of congestive heart failure
CHF has a positive LR of 5.8 and a
ratio: negative ratio of 0.66. Thus the
presence of a raised JVP rules-in the
diagnosis of CHF. Its absence is not as
useful in ruling it out.

22. Confirm &
Step 6 Comprehensively give a
Diagnostic Label

23. The BESDiagnosis Scheme
Better diagnostic labeling thereby assisting in
implementing individualized, evidence-
based interventions.
• 1. The Bed-side Clinical Diagnosis
• 2. The Etiological or Precipitating Cause
• 3. The Severity Score or Grade.

24. Guideline-friendly Bed-side “the
Diagnosis, Etiology, Severity (BESD) diagnosis
that would
explain all
Bedside
Clinical the
Diagnosis symptoms &
signs”
Etiological/ “what is the
Precipitant Cause”
•CURB-65: CAP
•Killip Classes: ACS “how bad”
•Glasgow CS
•Croup Score Severity
•APGAR Score
•Blatchford score: UGI bleed
•Ranson Score: Pancreatitis
•Emerg. Severity Index

25. Usefulness of The Scheme
• Failure to consider the precipitant or cause in
addition to the clinical diagnosis will inevitably
result in deficient care input and a poorer
outcome.
• Appropriate evidence-based interventions to
optimize outcome according to SEVERITY will
be different specifically with regards the sites of
care and recommended Immediate
Interventions.

26. Usefulness of The Scheme
• e.g.
• Usual Label: “Admitted with an asthma
exacerbation…………
• Guideline-Friendly Evidenced-Based Label:
1. The Bed-side Clinical Diagnosis: Asthma
Exacerbation
2. The Etiological or Precipitating Cause: Poor Inhaler
Technique
3. The Severity Score or Grade: Life-threatening
Asthma

27. Usefulness of The Scheme
• e.g. Continued….
• Implications:
• Site of Care: ICU
• Therapy for life-threatening attacks: Oxygen, systemic
steroids, combination nebs etc
• Prevention of re-admission: training on inhaler technique

28. Therapeutic
Step 7 Interventions

29. Step 7: Therapeutic Interventions: The
5S Scheme
• Contextual
• Patient-centered
– Therapeutic Cognitive Aid: Site of
Care, Symptomatic, Supportive, Specific and
Specialty Referral (5S).

30. Immediate Therapeutic Interventions:
The 5S
Site of Care e.g.
CCU
Symptomatic e.g.
Analgesics
e.g.
Supportive
IV fluids
e.g.
Specific thrombolytic
Specialty e.g.
Referral cardiology

31. The 5 S Scheme
• Site of Care: Guidelines, unambiguously dictate
sites of care for specific disease severity scores.
• ICU for CURB-65 of 3 or more
• CCU for Acute Coronary Syndrome

32. The 5 S Scheme
• Symptomatic treatment: is important as
it directly alleviates patient discomfort.
Analgesia for pain
Anti-emetics for nausea and vomiting
Anti-pyretics for fever

33. The 5 S Scheme
• Supportive care: to improve physiological
derangements before damage becomes
irreversible and until the precipitant is
brought under control by its specific
intervention may be life-saving.
IV Fluids for dehydration
Bicarbonate for acidosis
Oxygen for hypoxia

34. The 5 S Model
The 5 S Scheme
• Specific Care: directed at the primary
cause.
Antibiotics for infection
Thrombolytics for acute myocardial
infarction
Appendicectomy for acute appendicitis

35. The 5 S Model
The 5 S Scheme
• Specialty Referral: guidelines recommend
early specialty or sub-specialty referral for
specific acute illnesses.
GIT team for a patient with hematemesis
Cardiology for a patient with ACS
Physiotherapy for a patient with stroke

36. The complete input: An Example
1. Bedside-Clinical Diagnosis Acute BA Exacerbation
2. Precipitant Poor Inhaler Technique
3. Severity Life-threatening
4. Site of Care ICU
5. Symptomatic Bronchodilators
6. Supportive Oxygen, IV Fluids
7. Specific Bronchodilators, Steroids
8. Specialty Referral ICU, Pulmonary, Asthma Educator

37. Step 8 Prepare for Discharge

38. Step 8: Prepare for Discharge (ACT)
• Assess Response to Treatment (Subjective
& Objective)
• Criteria for Discharge
• Timing of Follow-up

39. The ACT Scheme
• Assess Response to Treatment: Subjective &
Objective
• Criteria for Discharge:
Clinical, Laboratory, Radiologic, Social etc
• Timing of Follow-up : Clinic Appointment for
disease and drug monitoring

40. Good
Luck