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INTERNIST-I/ CADUCEUS

INTERNIST-I/ CADUCEUS . A medical diagnostic assistant expert system Created By: Dr. Harry Pople, Dr. Jack Myers, and Randolph Miller. Goal. Cover a broad area of the internal medicine domain. Make accurate classification of the diseases that patients have

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INTERNIST-I/ CADUCEUS

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  1. INTERNIST-I/ CADUCEUS A medical diagnostic assistant expert system Created By: Dr. Harry Pople, Dr. Jack Myers, and Randolph Miller

  2. Goal • Cover a broad area of the internal medicine domain. • Make accurate classification of the diseases that patients have • Explain what caused the disease(s)

  3. Reasoning Like a Doctor • Try to model the method that doctors follow in diagnosis • Assumptions: • Doctors quickly narrow down possible disease(s) • The patient is assumed to have one disease until otherwise shown. (reduces the search space)

  4. The System • Task: Classification & Synthesis • Code: InterLisp • Data: • 500 diseases • 3500 manifestations • This covers 70-75% of internal medicine

  5. Data Structure • Pathophysiological(causal) Model – • A causal interaction of diseases, symptoms, derangements, abnormal lab values, etc… • Nosological Structure • A Taxonomy of disease (not a strict hierarchy)

  6. Terms • Manifestation – Findings • Symptom, sign, abnormal lab values… (Shock, Common duct stone, jaundice,…) • Disease Entity – Actual Disease • Gilbert’s Disease, Viral Hepatitis, …

  7. Syndromes, pathological derangements, and other entities Findings (Manifestations)  Disease Entities Causal Model - Manifestation - Disease States caused by … …

  8. caused by B is a Disease Entity A is a Symptom B A C is a syndrome C D is a Disease Entity E is an Abnormal Lab Value D E Causal Model - Manifestation - Disease States A is CAUSED BY B OR C A is CAUSED BY B A is CAUSED BY C is CAUSED BY D E is CAUSED BY D

  9. Causal Model

  10. Nosological Structure

  11. Manifestation*Import Manifestation*Evoking Manifestation*Frequency INTERNIST-I • Causal Model • Disease profile: (evoking strength, frequency) • Manifestation: (import value) • Method • Create a list of possible diseases evaluate the hypothesis to conclude a disease. • Score = Explained – Unexplained

  12. INITIAL POSITIVE MANIFESTATIONS: + AGE GTR THAN 55 + ARTHRITIS HX + DEPRESSION HX + SEX FEMALE + THYROIDECTOMY HX + ULCER PEPTIC HX + URINE DARK HX + WEIGHT INCREASE RECENT HX + ANOREXIA … + STOMACH BARIUM MEAL HIATAL HERNIA + DENY INITIAL NEGATIVE FINDINGS: -ALCOHOLISM CHRONIC HX -DIARRHEA CHRONIC -FECES BLACK TARRY -FEVER -PRESSURE VENOUS INCREASED ON INSPECTION … -ESOPHAGUS BARIUM MEAL VARICES -STOMACH BARIUM MEAL ULCER CRATER -T3 RESIN UPTAKE INCREASED -T4 TOTAL BLOOD INCREASED -GO DISREGARDING: DEPRESSION HX, WEIGHT INCREASE RECENT HX, CHEST PAIN LATERAL EXACERBATION WITH BREATHING, CHEST PAIN LATERAL SHARP, …, GLUCOSE BLOOD 130 TO 300, AMMONIA BLOOD INCREASED, ASCITIC FLUID WBC 100 TO 500, GLUCOSE TOLERANCE DECREASED CONSIDERING: AGE GTR THAN 55, SEX FEMALE, URINE DARK, ANOREXIA, FECES LIGHT COLORED, JAUNDICE, LIVER ENLARGED MODERATE, SKIN PALMAR ERYTHEMA, …, PROTHROMBIN TIME INCREASED, RHEUMATOID FACTOR POSITIVE. DISCRIMINATE: HEPATITIS CHRONIC ACTIVE, BILIARY CIRRHOSIS PRIMARY INTERNIST-I Example

  13. DISREGARDING: DEPRESSION HX, CHEST PAIN LATERAL EXACERBATION WITH BREATHING, CHEST PAIN LATERAL SHARP, …  CONSIDERING: WEIGHT INCREASE RECENT HX, ABDOMEN DISTENTION, ASCITIC FLUID PROTEIN 3 GRAM(S) PERCENT OR LESS ... CONCLUDE: TRANSUDATIVE ASCITES DISREGARDING: ... CONSIDERING: ASTERIXIS, PULSE PRESSURE INCREASED, TACHYCARDIA, AMMONIA BLOODINCREASED PURSUING: HEPATIC ENCEPHALOPATHY CSF FLUID OBTAINED? N/A CONCLUDE: HEPATIC ENCEPHALOPATHY Please Enter Findings of LIPID(S) BLOOD GO CHOLESTEROL BLOOD DECREASED? N/A Please Enter Findings of INSPECTION AND PALPITATION SKIN GO SKIN XANTHOMATA? NO Please Enter Findings of BLOOD COUNT AND SMEAR GO RBC TARGET(S)? NO … CONCLUDE: HEPATITIS CHRONIC ACTIVE INTERNIST-I Example

  14. INTERNIST-I Testing

  15. Problems • Knowledge-base errors • Data base incomplete/omissions (2) • Data base incorrect (2) • Lack of anatomic knowledge (1) • Failure to represent degree of severity (2) • Computer-program faults • Lack of temporal reasoning (3) • Failure of scoring algorithm (3) • Failure to seek global overview (1) • Improper attribution of findings to a concluded diagnosis (6)

  16. Solution: CADUCEUS • New Data Structure • Combine Causal and nosologic hierarchies • New Method: • State space search with evaluation across states. • Eliminate possible areas of hierarchies

  17. Data Structure

  18. CADUCEUS Results • CADUECUS is better then INTERNIST-I • Gets to answer faster • Less consultations to the doctor • Eliminates huge parts of the search right away • Lack of temporal reasoning

  19. Conclusion • Goal Met: • INTERNIST-I and CADUCEUS do cover a large area of internal medicine • Goal not met: • Accurately classify a patients diseases • Explain systems results to the user

  20. Questions

  21. Combinations

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