DOACs require dose adjustment or avoidance in severe CKD. Dabigatran is contraindicated if CrCl <30 mL/min. Apixaban (dose adjust) and rivaroxaban (avoid if CrCl <15) have different cutoffs. Warfarin remains an option but requires INR monitoring.

Elevated ICP >22 mmHg requires treatment. Elevating head of bed to 30° improves venous drainage, reducing ICP. Hyperventilation (temporizing), mannitol, and CSF drainage are subsequent steps. Avoid hypotonic fluids. Target CPP 60-70 mmHg.

Acute variceal hemorrhage: endoscopic band ligation (EBL) plus IV octreotide (vasoconstrictor). Prophylactic antibiotics (ceftriaxone) reduce rebleeding. TIPS reserved for refractory bleeding. Balloon tamponade is salvage therapy.

Class IV (diffuse proliferative) is most severe: >50% glomeruli involved with endocapillary proliferation, often with crescents. Class III (focal): <50%. Class V (membranous): subepithelial deposits without proliferation. Immunofluorescence shows "full house" (IgG, IgA, IgM, C3, C1q).

Bronchoalveolar lavage (BAL) with quantitative culture (>10⁴ CFU/mL) is gold standard. Endotracheal aspirate (>10⁵-10⁶ CFU/mL) is less specific but more accessible. Blind bronchial sampling (mini-BAL) is an alternative.

Persistent fever in neutropenia (ANC <500) after 48-72 hours of antibiotics: add empiric antifungal (caspofungin, liposomal amphotericin B, or voriconazole). CT chest for suspected aspergillosis. No clinical deterioration suggests fungal etiology.

Prone positioning (≥16 hours/day) reduces mortality in severe ARDS (PaO2/FiO2 <150). Neuromuscular blockade (cisatracurium for 48h) improves outcomes but mortality benefit less clear. ECMO rescue. High-frequency oscillation NOT beneficial.

Toxoplasma gondii encephalitis (CD4 <100). Empiric therapy: pyrimethamine + sulfadiazine + leucovorin (or TMP-SMX if allergic). Clinical improvement in 7-14 days supports diagnosis. Alternative: primary CNS lymphoma (EBV PCR in CSF).

Norepinephrine is first-line vasopressor in septic shock (increases MAP via alpha-1 and beta-1). Vasopressin (second-line, 0.03 U/min). Dopamine not recommended (arrhythmias). Epinephrine is second-line.

Post-MI with LVEF ≤30%: early implantable cardioverter-defibrillator (ICD) after 40 days (unless revascularization significantly improves EF). ACE inhibitors, beta-blockers, and spironolactone reduce mortality but not specifically sudden death.

EGFR mutation (exon 19 del or L858R): first-line osimertinib (third-generation TKI), also effective in T790M resistance. For progression on chemotherapy without prior TKI: osimertinib. Avoid gefitinib/erlotinib (first-gen) if osimertinib available.

Infected pancreatic necrosis with gas (emphysematous pancreatitis) requires step-up approach: antibiotics (carbapenem) then percutaneous or endoscopic necrosectomy/ drainage. Surgical necrosectomy delayed if possible (step-up reduces morbidity).