Episode 195: ARDS

We review Acute Respiratory Distress Syndrome Hosts: Sadakat Chowdhury, MD Brian Gilberti, MD https://media.blubrry.com/coreem/content.blubrry.com/coreem/ARDS.mp3 Download Leave a Comment Tags: Critical Care, Pulmonary 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), laboratory tests (complete blood count, basic metabolic panel, blood gases), and specialized tests depending on suspected etiology. Management Strategies: Steroids: Beneficial in certain etiologies of ARDS, with specifics on dosing and duration. Fluid Management: Conservative fluid strategy, diuresis guided by patient condition. Ventilation: Non-invasive ventilation (NIV) preferred in specific cases; mechanical ventilation strategies to ensure lung-protective ventilation. Proning: Used in severe ARDS to improve oxygenation. Inhaled Vasodilators: Used for refractory hypoxemia and specific complications like right heart failure. Extracorporeal Membrane Oxygenation (ECMO): Considered for severe ARDS as salvage therapy. Supportive Care: Includes monitoring and management of complications, nutrition, and physical therapy. Ventilation Specifics: Tidal volume and pressure settings aim for lung-protective strategies to prevent ventilator-induced lung injury. Permissive hypercapnia, plateau pressure, PEEP, and ventilation mode adjustments based on patient response. ARDSnet Table: ventilator_protocol_2008-07 Read More