Episode 195: ARDS

We review Acute Respiratory Distress Syndrome

Hosts:
Sadakat Chowdhury, MD
Brian Gilberti, MD

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Show Notes

• Definition of ARDS:
  • Non-cardiogenic pulmonary edema characterized by acute respiratory failure.
  • Berlin criteria for diagnosis include acute onset within 7 days, bilateral pulmonary infiltrates on imaging, not fully explained by cardiac failure or fluid overload, and impaired oxygenation with PaO2/FiO2 ratio <300 mmHg, even with positive end-expiratory pressure (PEEP) >5 cm H2O.
• Severity based on oxygenation (Berlin criteria):
  • Mild: PaO2/FiO2 200-300 mmHg
  • Moderate: PaO2/FiO2 100-200 mmHg
  • Severe: PaO2/FiO2 <100 mmHg
• Epidemiology:
  • Occurs in up to 23% of mechanically ventilated patients.
  • Mortality rate of 30-40%, primarily due to multiorgan failure.
• Differentiation from Cardiogenic Pulmonary Edema:
  • Chest CT shows diffuse edema and pleural effusion in cardiogenic edema; patchy edema, dense consolidation in ARDS.
  • Ultrasound may show diffuse B lines in cardiogenic edema; patchy B lines and normal A lines in ARDS.
• Pathophysiology:
  • Exudative phase: Immune-mediated alveolar damage, pulmonary edema, cytokine release.
  • Proliferative phase: Reabsorption of edema fluid.
  • Fibrotic phase: Potential for prolonged ventilation.
• Etiology:
  • Direct lung injury (pneumonia, toxins, aspiration, trauma, drowning) and indirect causes (sepsis, pancreatitis, transfusion reactions, certain drugs).
• Diagnostics:
  • Comprehensive workup including imaging (chest X-ray, CT),