Table 1: The 7 Expert Clinician’s Actions Map for a Patient Encounter and their Cognitive Schemes

Step Clinical Action Expert ‘s Scheme/Cognitive

Aid

Example

1 Gather Information (History & Physical)

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2 Summarize the Case using Technical Language

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.

67 yr old maleBird/pigeon breeder, smoker3 days history of fever, cough with yellow sputum, left stabbing chest pain that is worse with breathing and coughing and breathlessnessClinically, breathless, cyanosed, disoriented to time, person and place, Temperature 39.1C, BP 86/50, RR 32/min, bilateral coarse crepitations, bronchial breathing left lower zoneChest x-ray: left basal consolidation

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.

3 Propose a Diagnosis Pattern-recognition PR, Hypothetico-deductive Strategies HD (from H&P) and Smart Heuristics (Rules-of-Thumb), Rule-Out worst Scenario ROWS, Red Flags (symptoms or signs of more serious pathology) etc. The 3Rs!

High-Fidelity/Reliability Pattern Recognition (spot diagnosis): Shingles, Acromegalic FaciesLow-Fidelity/Reliability Pattern Recognition (error-prone): Central chest pain radiating to the left arm plus sweating=ACS (other possibilities still exist!)Smart Heuristic “Rules of Thumb”: early morning headache and vomiting=Increased intracranial pressureROWS: Meningitis, SAH, CVA etc in a patient with headacheRed Flags: rest pain, weight loss, neurological deficits etc in a patient with low back pain

4 Differential Diagnosis Differential Diagnosis Cognitive Aids: Anatomical, Physiological, Pathological

Anatomical: Swellings, Pain, AmenorrheaPhysiological: Shock, Thrombosis, HyponatremiaPathological: Traumatic, Infective, Inflammatory/auto-immune, Vascular/degenerative, Neoplastic/para-neoplastic, Metabolic/endocrine, Drug-induced/poisoning, Deficiency diseases, Psychogenic and Idiopathic/cryptogenic.

5 Order Tests (Rationally)

Frugal(simple and applicable) Heuristics Probability Assessment,Order tests: Test Sensitivity, Specificity and Likelihood Ratios

Pre-test Probability:

1. Strong Risk factor for the condition 2. No alternative DiagnosisHigh (2 YES) or Intermediate (1 YES 1 NO) or Low (2 NO) SpIn: highly specific tests are useful for ruling-in the diagnosis when positive ( use for high and intermediate probabilities)SnOut: highly sensitive tests are useful for ruling-out the diagnosis when negative ( use for low probabilities)

6 Confirm & Comprehensively give a Diagnostic Label

Guideline-friendly Bed-side Diagnosis, Etiology, Severity (BESD)

Bed-side Diagnosis: CAPEtiology: Chlamydia psittaciSeverity: CURB-65= 4

7 Therapeutic Interventions

Contextual, Patient-centered Therapeutic Cognitive Aid: Site of Care, Symptomatic, Supportive, Specific and Specialty Referral (5S).

Site of Care: Ward, CCU, ICU etcSymptomatic: Analgesia, Anti-emetic, Anti-pyretic etcSupportive: Oxygen, IV fluids, Bicarbonate etcSpecific: Antibiotic, Thrombolytic, Cytotoxic etcSpecialty Referral: Cardiology, Surgery, Gynecology, Physiotherapy etc

8 Prepare for Discharge

Assess Response to Treatment (Subjective & Objective), Criteria for Discharge, Timing of Follow-up (ACT)

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

Box 1: Summarizing the History and Physical Examination

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.

Table 2: Differential Diagnosis Cognitive Aids

Anatomical Differential Diagnosis

Physiological Differential Diagnosis

Etio-pathological Differential Diagnosis

Pain Syndromes: e.g. central chest pain may be categorized as arising from the heart, aorta, esophagus, chest wall etc

Shock: this may be hypovolemic, distributive, obstructive or cardiogenic

Congenital or Hereditary

Swellings: e.g. a neck swelling differential diagnosis will include the thyroid, lymph nodes, vascular, skin etc

Thrombosis: This may be related to a vessel wall pathology, blood constituents or flow rate.

Acquired: 1. Traumatic2. Infective: viral, bacterial

etc3. Inflammatory/auto-

immune4. Vascular/degenerative5. Neoplastic/para-

neoplastic6. Metabolic/endocrine7. Drug-induced/ poisoning8. Deficiency diseases9. Psychogenic 10. Idiopathic/cryptogenic

Table 3: Sensitivity, Specificity and Likelihood Ratios: Definitions and Examples

Sensitivity SENSITIVITYHow often is the test result correct for persons in whom the disease is known to be present? Sensitivity - the proportion of people with disease who have a positive test.

Example: in a group of 100 patients with bacterial pneumonia, 80 had a raised C-reactive protein CRP: the sensitivity of CRP for diagnosing bacterial pneumonia is thus 80%.

Specificity SPECIFICITYHow often is the test result correct for persons in whom the disease is known to be absent?Specificity - the proportion of people without the disease who have a negative test.

Example: in a group of 100 patients without pneumonia, 10 had a raised C-reactive protein CRP: the specificity of CRP for correctly excluding pneumonia is thus 90%.

Likelihood Ratio

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 result would be expected in a patient without that disorder.In general, a positive likelihood ratio of 4 or 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.

Example: A raised Jugular venous pressure JVP in a patient with a history suggestive of congestive heart failure CHF has a positive LR of 5.8 and a 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.