Summary of Acute Respiratory Distress Syndrome (ARDS)

Acute Respiratory Distress Syndrome (ARDS)

Definition and Terminology

  • ARDS refers to severe inflammatory lung injury leading to respiratory failure.

  • Other names include:

    • Adult respiratory distress syndrome

    • Capillary leak syndrome

    • Noncardiac pulmonary edema

    • Shock lung syndrome

Causes

  • Sepsis (most common cause)

  • Aspiration

  • CNS diseases

  • Cardiopulmonary bypass

  • DIC (Disseminated intravascular coagulation)

  • Severe trauma or burns

  • Fat or air emboli

  • Infections and inhalation of toxins

  • Oxygen toxicity (prolonged exposure to FiO2 > 0.60)

Clinical Examination

  • Vital signs: Increased respiratory rate (tachypnea), heart rate, and blood pressure

  • Chest assessment: Dull percussion note, bronchial breath sounds, crackles, cyanosis

Radiologic Findings

  • Chest radiograph shows increased opacity and ground-glass appearance

Berlin Definition of ARDS

  • Mild ARDS: P/F Ratio > 200 mmHg but < 300 mmHg

  • Moderate ARDS: P/F Ratio > 100 mmHg

  • Severe ARDS: P/F Ratio < 100 mmHg

  • Rule out cardiogenic pulmonary edema

Treatment Protocols

Oxygen Therapy

  • Address hypoxemia due to alveolar consolidation and atelectasis

Mechanical Ventilation

  • Immediate invasive ventilation if ARDS suspected

  • Strategies include low tidal volumes (6 to 8 mL/kg) and higher respiratory rates (20 to 35 bpm)

  • PEEP or CPAP used to offset atelectasis

  • Allow permissive hypercapnia

Goals of Low-Tidal Volume Ventilation

  • Decrease high transpulmonary pressure

  • Reduce lung overdistention

  • Minimize barotrauma

Medications

  • Commonly prescribed: Antibiotics, diuretics