Source / episode info
- **Episode:**141
- **Title:**Divine Intervention Episode 141 – USMLE Step 2CK Rapid Review Series 13 (IM)
- **Published:**2019-08-23
- Source:Episode page
One-liner
This episode provides rapid review of high-yield internal medicine topics including acute cholecystitis workup variations, differentiating pleural effusion types using Light's criteria, managing various infectious diarrheas (e.g., Vibrio cholerae, Giardia), understanding coagulation testing principles, and recognizing the pathophysiology of ARDS.
High-yield summary
- Acute Cholecystitis Workup: If RUQ ultrasound is equivocal or negative, proceed with a HIDA scan. A positive test for acute cholecystitis is failure to visualize the gallbladder at 90 minutes post-morphine administration.
- Ecalculous Cholecystitis Management: In high-risk patients (e.g., on TPN, in ICU), do NOT perform an elective cholecystectomy; instead, utilize a percutaneous cholecystostomy to decompress the gallbladder.
- Pleural Effusion Classification: An effusion is exudative if any of the following Light's criteria are met: 1) Pleural fluid/serum protein ratio > 0.5, 2) Pleural fluid/serum LDH ratio > 0.6, or 3) Pleural fluid LDH > 2/3 ULN.
- ARDS Pathophysiology: Non-cardiogenic pulmonary edema (ARDS) is characterized by increased permeability of the pulmonary vasculature and is diagnosed when the Pulmonary Capillary Wedge Pressure (PCWP) is low (< 18 mmHg), despite severe hypoxemia.
- Coagulation Testing Traps: Warfarin inhibits Vitamin K, leading to decreased synthesis of Factors II, VII, IX, and X. Therefore, it elevates both PT and aPTT. Heparin primarily prolongs the aPTT.
Learning objectives
- Differentiate the diagnostic workup for acute cholecystitis using ultrasound vs. HIDA scan.
- Apply Light's criteria accurately to classify pleural effusions as transudative or exudative.
- Recognize the specific pathogens and clinical presentations associated with various diarrheal syndromes (e.g., Giardia, Vibrio cholerae).
- Understand the pathophysiology of ARDS, particularly differentiating it from cardiogenic pulmonary edema using PCWP.
- Master the principles of coagulation testing interpretation, especially concerning anticoagulants like Warfarin and Heparin.
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