319.3 🏥 內科專科考前版

319.3.1 Mechanistic Deep Dive

319.3.1.1 Aspiration Pathophysiology

  • 3 mechanisms:
    1. Mechanical obstruction (large food)
    2. Chemical injury (acid)
    3. Bacterial infection
  • Volume + acidity + frequency determine outcome
  • Microaspiration common (50% normal during sleep)

319.3.1.2 Anaerobic Bacterial Ecology

  • Oral cavity reservoir
  • Periodontal disease ↑ load
  • Aspiration into lung
  • Polymicrobial typical
  • Difficult to culture
  • Antibiotic activity matters

319.3.2 Recent Trials & Updates

319.3.2.1 Reassessment of Anaerobic Predominance

  • Modern molecular studies show aerobes very common
  • Antibiotic spectrum should cover both
  • Amox-clav or pip-tazo good choices

319.3.2.2 Stroke Care + Dysphagia Bundle

  • AHA Class I
  • Reduces aspiration pneumonia
  • Screening + SLP + diet modification

319.3.2.3 PEG vs NG Tube Aspiration Risk

  • PEG does NOT eliminate aspiration risk in dementia
  • Quality of life considerations
  • Family preference + goals of care

319.3.2.4 Aspiration Prevention in Mechanical Ventilation

  • VAP bundle (Ch317)
  • Subglottic suction tubes
  • HOB elevation

319.3.3 High-Yield Specialist Points

319.3.3.1 Dysphagia in Stroke

  • 50-80% of acute stroke patients
  • Aspiration pneumonia in 5-15%
  • Screening within 24 hours (Class I)
  • Persistent dysphagia → SLP eval + modified diet
  • 50% resolve in 1 month

319.3.3.2 Parkinson Disease + Aspiration

  • Most common cause of death
  • Dopaminergic dysphagia
  • LSVT-LOUD therapy
  • Multidisciplinary management

319.3.3.3 ALS + Aspiration

  • Progressive bulbar dysfunction
  • NIV for respiratory support
  • PEG tube for nutrition
  • Aspiration is common cause of death

319.3.3.4 Lung Abscess Bronchoscopy

  • Indications: rule out foreign body, mass, atypical infection
  • Risk: contamination of unaffected lung
  • Timing: usually after antibiotics for 1-2 weeks
  • Selective in patients

319.3.3.5 Necrotizing Pneumonia Workup

  • Often Klebsiella, S. aureus, Acinetobacter, B. cepacia
  • Aggressive antibiotic therapy
  • Surgical resection rarely
  • Search for underlying immunocompromise

319.3.3.6 Septic Pulmonary Embolism Algorithm

  • Multiple bilateral cavitating nodules
  • Often with peripheral wedges
  • Source workup: tricuspid endocarditis, central line, pelvic abscess
  • Treat as endocarditis (Ch297) + standard antibiotics

319.3.3.7 PEG Tube + Dysphagia (Controversial)

  • Original belief: reduces aspiration
  • Evidence: does NOT prevent aspiration in dementia
  • QOL considerations
  • Family + goals discussion
  • Modified diet may be alternative

319.3.3.8 Aspiration in Acute Stroke

  • Critical first 24-48 hours
  • Dysphagia screen + NPO until cleared
  • IVF + alternate route during NPO
  • Multidisciplinary care

319.3.4 Pearls

  • Aspiration pneumonia = polymicrobial; dependent lobes
  • Mendelson syndrome = acid; no routine antibiotics
  • Treatment: amox-clav or pip-tazo (anaerobic cover)
  • Lung abscess: cavitation; 4-6 week antibiotics; drainage usually not needed
  • Septic pulmonary embolism: S. aureus (endocarditis); multiple cavities
  • Prevention bundle: SLP, thickened liquids, HOB ≥ 30°, oral hygiene
  • Stroke dysphagia screening within 24 hours (Class I)