Acute respiratory distress syndrome (ARDS)

Case history

A 60-year-old man presents with acute onset of shortness of breath, fever, and cough. A chest x-ray shows a right lower lobe infiltrate, and sputum has gram-positive diplococci. He is given intravenous antibiotics but his respiratory status declines over 24 hours. He becomes hypotensive and is transferred to the intensive care unit. He is intubated for hypoxaemia and requires vasopressors for septic shock despite adequate volume resuscitation. He requires high levels of inspired oxygen (FiO₂) and positive end-expiratory pressure on the ventilator to keep his oxygen saturation >90%. Repeat chest x-ray shows bilateral alveolar infiltrates, and his partial pressure of oxygen, arterial (PaO₂)/FiO₂ ratio is 109.