ARDS


Diagnosis
  1. Severe respiratory distress
  2. Impaired oxygenation as seen on ABG with PaO2 ratio <200
  3. Bilateral pulm infiltrates (although CXR may initially be normal)
  4. Hypoxemia is usually refractory to O2, with rapidly incr O2 requirement
  5. With invasive monitoring, pulm capillary wedge pressure <18 mm Hg rules out cardiogenic pulm edema

Pathophysiology

  1. Diffuse alveolar damage secondary to structural changes in alveolocapillary unit
  2. Alveolocapillary membrane injury disrupts endothelial barrier causing non-cardiac pulm edema
  3. Alveolar air spaces fill w/plasma fluid and proteins causing shunting
  4. Common predisposing factors incl aspiration/inhalational injury/sepsis/pancreatitis/fat embolism/amniotic fluid embolism/trauma

Treatment

  1. Most important tx is to treat underling etiology
  2. No specific measures to counteract injury to alveolocapillary membrane
  3. Treatment is supportive and incl intubation and mechanical ventilation
  4. PEEP to achieve O2 sats >90% (typical PEEP 8/W 5-10)
  5. Lung infiltrates may not be uniform, changes in position may incr oxygenation
  6. Some advocate keeping pt on dry side w/fluid restriction or diuresis
  7. Steroids may be used late in course

Disposition

  1. Admit to ICU