315.3 🏥 內科專科考前版

315.3.1 Mechanistic Deep Dive

315.3.1.1 VILI (Ventilator-Induced Lung Injury)

  • Volutrauma (large Vt → stretch injury)
  • Barotrauma (high pressure)
  • Atelectotrauma (cyclic opening/closing → stress)
  • Biotrauma (mechanical → biological inflammation cascade)

315.3.1.2 Lung Mechanics in ARDS

  • Reduced compliance
  • Heterogeneous disease (baby lung concept)
  • Driving pressure reflects lung mechanics
  • Stress-strain relationship

315.3.1.3 ARDS Pathobiology

  • Type I + II pneumocyte injury
  • Endothelial dysfunction
  • Inflammation cascade (TNF, IL-6, IL-8)
  • Coagulation activation (PAI-1, microthrombi)
  • Surfactant dysfunction
  • Fibrosis in proliferative phase

315.3.2 Recent Trials & Updates

315.3.2.1 EOLIA (2018) — VV-ECMO

  • Severe ARDS
  • ECMO referral early
  • Borderline mortality benefit (high crossover)
  • Bayesian analysis suggests probable benefit
  • Practice: refer early to ECMO center

315.3.2.2 COVID-19 ARDS Trials (2020-2024)

  • RECOVERY: dexamethasone
  • REMAP-CAP: tocilizumab, baricitinib
  • COV-BARRIER: baricitinib
  • Awake proning: PROPI, COVID-PRONE — mixed
  • Steroids + anti-IL-6 + JAK inhibitor backbone

315.3.2.3 ARDSnet Trials Series

  • ARMA: lung-protective ventilation
  • ALVEOLI: PEEP titration
  • LOVS: high PEEP strategy
  • ExPress: 6 cohort
  • FACTT: fluid management

315.3.2.4 MENDS-2 (2024) — Dexmedetomidine vs Propofol

  • ARDS sedation
  • Equivalent outcomes
  • Less delirium with dex
  • Useful for sedation strategy

315.3.2.5 TLR-4 Pathway (Future Therapy)

  • Investigational antagonists
  • Inflammation modulation

315.3.2.6 Specific Biomarkers

  • IL-6, IL-8, sTNFR1, RAGE
  • Stratify subphenotypes
  • Predict response to therapies

315.3.3 High-Yield Specialist Points

315.3.3.1 Recruitment Maneuver

  • Brief high PEEP (30-40) to open collapsed alveoli
  • ART trial (2017): NO improvement, may harm
  • Reserved for selected severe with hypoxia

315.3.3.2 High Flow Nasal Cannula (HFNC)

  • Heated humidified high-flow O2
  • For hypoxemic respiratory failure
  • FLORALI (2015): comparable to mask O2 + NIV
  • Awake proning + HFNC for COVID
  • Comfortable, well-tolerated

315.3.3.3 Awake Proning

  • For non-intubated patients with hypoxemic respiratory failure
  • COVID-19 era widespread use
  • COVID-PRONE, others mixed evidence
  • Practical, low-cost intervention

315.3.3.4 Cytokine Storm + ARDS

  • COVID-19 highlighted role
  • Anti-IL-6 (tocilizumab, sarilumab) effective
  • Baricitinib (JAK inhibitor) effective
  • IL-1β blockade (anakinra) less effective in trials

315.3.3.6 Driving Pressure-Based Ventilation

  • ↓ Vt + ↑ PEEP to optimize driving pressure
  • Personalized titration
  • Future direction

315.3.3.7 Esophageal Pressure Monitoring

  • Estimates transpulmonary pressure
  • For obesity, abdominal compartment syndrome
  • EPVent trial: 2023 results modest

315.3.3.8 Prone Positioning Logistics

  • Multidisciplinary team
  • ICU resources
  • Complications: pressure injuries, line displacement, eye injury
  • 12-16 hours/day in severe ARDS

315.3.3.9 Lung Transplant Post-ARDS

  • For severe ongoing respiratory failure + irreversible lung injury
  • Rare; selected
  • Complex post-ICU rehabilitation

315.3.3.10 Long-Term Outcomes ARDS

  • Survivors have:
    • Reduced exercise capacity
    • Pulmonary function abnormalities (DLCO ↓ most consistent)
    • Cognitive impairment
    • Mood disorders
    • Functional decline
  • Multidisciplinary rehabilitation

315.3.4 Pearls

  • ARDS Berlin Criteria 2012: timing + bilateral + not cardiac + PaO2/FiO2 < 300 PEEP ≥ 5
  • Severity: mild 200-300, moderate 100-200, severe ≀ 100
  • ARMA (lung-protective): Vt 6 mL/kg PBW, plateau < 30
  • Driving pressure < 15 cm H2O (Amato): best survival predictor
  • PROSEVA: prone for severe ARDS ↓ mortality 16%
  • NMB: ACURASYS positive; ROSE neutral; use for refractory dyssynchrony
  • FACTT: conservative fluid ↑ ventilator-free days
  • ECMO: refractory (PaO2/FiO2 < 80, pH < 7.20); CESAR + EOLIA
  • RECOVERY: dexamethasone for COVID-ARDS
  • REMAP-CAP: tocilizumab + baricitinib